S Li, J Wang, J V Andersen, B I Aldana, B Zhang, E V Prochownik, P A Rosenberg
We have previously reported a failure of recovery of synaptic function in the CA1 region of acute hippocampal slices from mice with a conditional neuronal knockout (KO) of GLT-1 (EAAT2, Slc1A2) driven by synapsin-Cre (synGLT-1 KO). The failure of recovery of synaptic function is due to excitotoxic injury. We hypothesized that changes in mitochondrial metabolism contribute to the heightened vulnerability to excitotoxicity in the synGLT-1 KO mice. We found impaired flux of carbon from 13C-glucose into the tricarboxylic acid cycle in synGLT-1 KO cortical and hippocampal slices compared with wild-type (WT) slices. In addition, we found downregulation of the neuronal glucose transporter GLUT3 in both genotypes. Flux of carbon from [1,2-13C]acetate, thought to be astrocyte-specific, was increased in the synGLT-KO hippocampal slices but not cortical slices. Glycogen stores, predominantly localized to astrocytes, are rapidly depleted in slices after cutting, and are replenished during ex vivo incubation. In the synGLT-1 KO, replenishment of glycogen stores during ex vivo incubation was compromised. These results suggest both neuronal and astrocytic metabolic perturbations in the synGLT-1 KO slices. Supplementing incubation medium during recovery with 20 mM D-glucose normalized glycogen replenishment but had no effect on recovery of synaptic function. In contrast, 20 mM non-metabolizable L-glucose substantially improved recovery of synaptic function, suggesting that D-glucose metabolism contributes to the excitotoxic injury in the synGLT-1 KO slices. L-lactate substitution for D-glucose did not promote recovery of synaptic function, implicating mitochondrial metabolism. Consistent with this hypothesis, phosphorylation of pyruvate dehydrogenase, which decreases enzyme activity, was increased in WT slices during the recovery period, but not in synGLT-1 KO slices. Since metabolism of glucose by the mitochondrial electron transport chain is associated with superoxide production, we tested the effect of drugs that scavenge and prevent superoxide production. The superoxide dismutase/catalase mimic EUK-134 conferred complete protection and full recovery of synaptic function. A site-specific inhibitor of complex III superoxide production, S3QEL-2, was also protective, but inhibitors of NADPH oxidase were not. In summary, we find that the failure of recovery of synaptic function in hippocampal slices from the synGLT-1 KO mouse, previously shown to be due to excitotoxic injury, is caused by production of superoxide by mitochondrial metabolism.
我们以前曾报道过,在突触素-Cre(synapsin-Cre,synGLT-1 KO)驱动的条件性神经元敲除(KO)GLT-1(EAAT2,Slc1A2)的小鼠急性海马切片的CA1区,突触功能未能恢复。突触功能无法恢复的原因是兴奋毒性损伤。我们推测,线粒体代谢的变化是导致 synGLT-1 KO 小鼠更易受兴奋毒性伤害的原因。与野生型(WT)切片相比,我们发现在 synGLT-1 KO 小鼠的皮质和海马切片中,13C-葡萄糖进入三羧酸循环的碳通量受损。此外,我们还发现两种基因型的神经元葡萄糖转运体 GLUT3 均出现下调。在 synGLT-KO 海马切片中,被认为是星形胶质细胞特异性的 [1,2-13C] 乙酸的碳通量增加了,但在大脑皮层切片中却没有增加。糖原储存主要定位于星形胶质细胞,切片后会迅速耗尽,并在体外培养过程中得到补充。在 synGLT-1 KO 中,体内外培养期间糖原储存的补充受到影响。这些结果表明,在 synGLT-1 KO 切片中,神经元和星形胶质细胞的代谢都受到了干扰。在恢复期间用 20 mM D-葡萄糖补充培养基可使糖原补充正常化,但对突触功能的恢复没有影响。与此相反,20 mM 不可代谢的 L-葡萄糖大大改善了突触功能的恢复,这表明 D-葡萄糖代谢是 synGLT-1 KO 切片兴奋毒性损伤的原因之一。用 L-乳酸替代 D-葡萄糖并不能促进突触功能的恢复,这与线粒体代谢有关。与这一假设相一致的是,丙酮酸脱氢酶的磷酸化会降低酶的活性,而在恢复期间,WT 切片的丙酮酸脱氢酶的磷酸化会增加,但在 synGLT-1 KO 切片中则不会。由于线粒体电子传递链的葡萄糖代谢与超氧化物的产生有关,我们测试了清除和防止超氧化物产生的药物的效果。超氧化物歧化酶/催化酶模拟物 EUK-134 能提供完全保护并完全恢复突触功能。复合体 III 超氧化物产生的位点特异性抑制剂 S3QEL-2 也具有保护作用,但 NADPH 氧化酶抑制剂则没有保护作用。总之,我们发现,之前被证明是兴奋毒性损伤导致的 synGLT-1 KO 小鼠海马切片突触功能恢复失败,是由线粒体代谢产生的超氧化物引起的。
{"title":"Misprogramming of glucose metabolism impairs recovery of hippocampal slices from neuronal GLT-1 knockout mice and contributes to excitotoxic injury through mitochondrial superoxide production.","authors":"S Li, J Wang, J V Andersen, B I Aldana, B Zhang, E V Prochownik, P A Rosenberg","doi":"10.1111/jnc.16205","DOIUrl":"https://doi.org/10.1111/jnc.16205","url":null,"abstract":"<p><p>We have previously reported a failure of recovery of synaptic function in the CA1 region of acute hippocampal slices from mice with a conditional neuronal knockout (KO) of GLT-1 (EAAT2, Slc1A2) driven by synapsin-Cre (synGLT-1 KO). The failure of recovery of synaptic function is due to excitotoxic injury. We hypothesized that changes in mitochondrial metabolism contribute to the heightened vulnerability to excitotoxicity in the synGLT-1 KO mice. We found impaired flux of carbon from <sup>13</sup>C-glucose into the tricarboxylic acid cycle in synGLT-1 KO cortical and hippocampal slices compared with wild-type (WT) slices. In addition, we found downregulation of the neuronal glucose transporter GLUT3 in both genotypes. Flux of carbon from [1,2-<sup>13</sup>C]acetate, thought to be astrocyte-specific, was increased in the synGLT-KO hippocampal slices but not cortical slices. Glycogen stores, predominantly localized to astrocytes, are rapidly depleted in slices after cutting, and are replenished during ex vivo incubation. In the synGLT-1 KO, replenishment of glycogen stores during ex vivo incubation was compromised. These results suggest both neuronal and astrocytic metabolic perturbations in the synGLT-1 KO slices. Supplementing incubation medium during recovery with 20 mM D-glucose normalized glycogen replenishment but had no effect on recovery of synaptic function. In contrast, 20 mM non-metabolizable L-glucose substantially improved recovery of synaptic function, suggesting that D-glucose metabolism contributes to the excitotoxic injury in the synGLT-1 KO slices. L-lactate substitution for D-glucose did not promote recovery of synaptic function, implicating mitochondrial metabolism. Consistent with this hypothesis, phosphorylation of pyruvate dehydrogenase, which decreases enzyme activity, was increased in WT slices during the recovery period, but not in synGLT-1 KO slices. Since metabolism of glucose by the mitochondrial electron transport chain is associated with superoxide production, we tested the effect of drugs that scavenge and prevent superoxide production. The superoxide dismutase/catalase mimic EUK-134 conferred complete protection and full recovery of synaptic function. A site-specific inhibitor of complex III superoxide production, S3QEL-2, was also protective, but inhibitors of NADPH oxidase were not. In summary, we find that the failure of recovery of synaptic function in hippocampal slices from the synGLT-1 KO mouse, previously shown to be due to excitotoxic injury, is caused by production of superoxide by mitochondrial metabolism.</p>","PeriodicalId":16527,"journal":{"name":"Journal of Neurochemistry","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142080625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mary C McKenna, Ursula Sonnewald, Helle S Waageptersen, H Steve White
This is a tribute to Arne Schousboe, Professor Emeritus at the University of Copenhagen, an eminent neurochemist and neuroscientist who was a leader in the fields of GABA, glutamate, and brain energy metabolism. Arne was known for his keen intellect, his wide-ranging expertise in neurochemistry and neuropharmacology of GABA and glutamate and brain energy metabolism. Arne was also known for his strong leadership, his warm and engaging personality and his enjoyment of fine wine and great food shared with friends, family, and colleagues. Sadly, Arne passed away on February 27, 2024, after a short illness. He is survived by his wife Inger Schousboe, his two children, and three wonderful grandchildren. His death is a tremendous loss to the neuroscience community. He will be greatly missed by his friends, family, and colleagues. Some of the highlights of Arne's career are described in this tribute.
{"title":"A tribute to Arne Schousboe's contributions to neurochemistry and his innovative and enduring research in GABA, glutamate, and brain energy metabolism.","authors":"Mary C McKenna, Ursula Sonnewald, Helle S Waageptersen, H Steve White","doi":"10.1111/jnc.16207","DOIUrl":"https://doi.org/10.1111/jnc.16207","url":null,"abstract":"<p><p>This is a tribute to Arne Schousboe, Professor Emeritus at the University of Copenhagen, an eminent neurochemist and neuroscientist who was a leader in the fields of GABA, glutamate, and brain energy metabolism. Arne was known for his keen intellect, his wide-ranging expertise in neurochemistry and neuropharmacology of GABA and glutamate and brain energy metabolism. Arne was also known for his strong leadership, his warm and engaging personality and his enjoyment of fine wine and great food shared with friends, family, and colleagues. Sadly, Arne passed away on February 27, 2024, after a short illness. He is survived by his wife Inger Schousboe, his two children, and three wonderful grandchildren. His death is a tremendous loss to the neuroscience community. He will be greatly missed by his friends, family, and colleagues. Some of the highlights of Arne's career are described in this tribute.</p>","PeriodicalId":16527,"journal":{"name":"Journal of Neurochemistry","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142055829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maternal immune activation (MIA) induces a variety of behavioral and brain abnormalities in offspring of rodent models, compatible with neurodevelopmental disorders, such as schizophrenia or autism. However, it remains controversial whether MIA impairs reversal learning, a basic expression of cognitive flexibility that seems to be altered in schizophrenia. In the present study, MIA was induced by administration of a single dose of polyriboinosinic-polyribocytidylic acid (Poly (I:C) (5 mg/kg i.p.)) or saline to mouse pregnant dams in gestational day (GD) 9.5. Immune activation was monitored through changes in weight and temperature. The offspring were evaluated when they reached adulthood (8 weeks) using a touchscreen-based system to investigate the effects of Poly (I:C) on discrimination and reversal learning performance. After an initial pre-training, mice were trained to discriminate between two different stimuli, of which only one was rewarded (acquisition phase). When the correct response reached above 80% values for two consecutive days, the images were reversed (reversal phase) to assess the adaptation capacity to a changing environment. Maternal Poly (I:C) treatment did not interfere with the learning process but induced deficits in reversal learning compared to control saline animals. Thus, the accuracy in the reversal phase was lower, and Poly (I:C) animals required more sessions to complete it, suggesting impairments in cognitive flexibility. This study advances the knowledge of how MIA affects behavior, especially cognitive domains that are impaired in schizophrenia. The findings support the validity of the Poly (I:C)-based MIA model as a tool to develop pharmacological treatments targeting cognitive deficits associated with neurodevelopmental disorders.
{"title":"Poly (I:C)-induced maternal immune activation generates impairment of reversal learning performance in offspring.","authors":"Eva Munarriz-Cuezva, Jose Javier Meana","doi":"10.1111/jnc.16212","DOIUrl":"https://doi.org/10.1111/jnc.16212","url":null,"abstract":"<p><p>Maternal immune activation (MIA) induces a variety of behavioral and brain abnormalities in offspring of rodent models, compatible with neurodevelopmental disorders, such as schizophrenia or autism. However, it remains controversial whether MIA impairs reversal learning, a basic expression of cognitive flexibility that seems to be altered in schizophrenia. In the present study, MIA was induced by administration of a single dose of polyriboinosinic-polyribocytidylic acid (Poly (I:C) (5 mg/kg i.p.)) or saline to mouse pregnant dams in gestational day (GD) 9.5. Immune activation was monitored through changes in weight and temperature. The offspring were evaluated when they reached adulthood (8 weeks) using a touchscreen-based system to investigate the effects of Poly (I:C) on discrimination and reversal learning performance. After an initial pre-training, mice were trained to discriminate between two different stimuli, of which only one was rewarded (acquisition phase). When the correct response reached above 80% values for two consecutive days, the images were reversed (reversal phase) to assess the adaptation capacity to a changing environment. Maternal Poly (I:C) treatment did not interfere with the learning process but induced deficits in reversal learning compared to control saline animals. Thus, the accuracy in the reversal phase was lower, and Poly (I:C) animals required more sessions to complete it, suggesting impairments in cognitive flexibility. This study advances the knowledge of how MIA affects behavior, especially cognitive domains that are impaired in schizophrenia. The findings support the validity of the Poly (I:C)-based MIA model as a tool to develop pharmacological treatments targeting cognitive deficits associated with neurodevelopmental disorders.</p>","PeriodicalId":16527,"journal":{"name":"Journal of Neurochemistry","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142055831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yoon-Beom Lee, Yohan Park, Amir Hamza, Jung Ki Min, Oyungerel Dogsom, Sung-Chan Kim, Jae-Bong Park
Epidermal growth factor (EGF) is known to be a critical stimulant for inducing the proliferation of glioma cancer cells. In our study, we observed that GST-RhoA binds to pyruvate kinase M2 (PKM2) in vitro. While EGF reduced the levels of RhoA protein, it significantly increased p-Y42 RhoA, as well as PKM1 and PKM2 in LN18 glioma cell line. We determined that RhoA undergoes degradation through ubiquitination involving SCF1 and Smurf1. Interestingly, we observed that p-Y42 RhoA binds to PKM2, while the dephosphomimetic form, RhoA Y42F, did not. Additionally, our observation revealed that PKM2 stabilized both RhoA and p-Y42 RhoA. Importantly, RhoA, p-Y42 RhoA, and PKM2, but not RhoA-GTP, were localized in the nucleus upon EGF stimulation. Knockdown of RhoA with siRNA resulted in the reduced levels of phosphoglycerate kinase1 (PGK1) and microtubule affinity-regulating kinase 4 (MARK). Furthermore, we found that the promoter of PGK1 was associated with β-catenin and YAP. Notably, p-Y42 RhoA and PKM2 co-immunoprecipitated with β-catenin and YAP. Based on these findings, we proposed a novel mechanism by which p-Y42 RhoA and PKM2, in conjunction with β-catenin and YAP, regulate PGK1 expression, contributing to the progression of glioma upon EGF.
{"title":"Function of a complex of p-Y42 RhoA GTPase and pyruvate kinase M2 in EGF signaling pathway in glioma cells.","authors":"Yoon-Beom Lee, Yohan Park, Amir Hamza, Jung Ki Min, Oyungerel Dogsom, Sung-Chan Kim, Jae-Bong Park","doi":"10.1111/jnc.16210","DOIUrl":"https://doi.org/10.1111/jnc.16210","url":null,"abstract":"<p><p>Epidermal growth factor (EGF) is known to be a critical stimulant for inducing the proliferation of glioma cancer cells. In our study, we observed that GST-RhoA binds to pyruvate kinase M2 (PKM2) in vitro. While EGF reduced the levels of RhoA protein, it significantly increased p-Y42 RhoA, as well as PKM1 and PKM2 in LN18 glioma cell line. We determined that RhoA undergoes degradation through ubiquitination involving SCF1 and Smurf1. Interestingly, we observed that p-Y42 RhoA binds to PKM2, while the dephosphomimetic form, RhoA Y42F, did not. Additionally, our observation revealed that PKM2 stabilized both RhoA and p-Y42 RhoA. Importantly, RhoA, p-Y42 RhoA, and PKM2, but not RhoA-GTP, were localized in the nucleus upon EGF stimulation. Knockdown of RhoA with siRNA resulted in the reduced levels of phosphoglycerate kinase1 (PGK1) and microtubule affinity-regulating kinase 4 (MARK). Furthermore, we found that the promoter of PGK1 was associated with β-catenin and YAP. Notably, p-Y42 RhoA and PKM2 co-immunoprecipitated with β-catenin and YAP. Based on these findings, we proposed a novel mechanism by which p-Y42 RhoA and PKM2, in conjunction with β-catenin and YAP, regulate PGK1 expression, contributing to the progression of glioma upon EGF.</p>","PeriodicalId":16527,"journal":{"name":"Journal of Neurochemistry","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142055830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sabrina Montresor, Maria Lucia Pigazzini, Sudarson Baskaran, Mira Sleiman, Govinda Adhikari, Lukas Basilicata, Luca Secker, Natascha Jacob, Yara Ehlert, Anushree Kelkar, Gurleen Kaur Kalsi, Niraj Kulkarni, Paul Spellerberg, Janine Kirstein
Chaperones safeguard protein homeostasis by promoting folding and preventing aggregation. HSP110 is a cytosolic chaperone that functions as a nucleotide exchange factor for the HSP70 cycle. Together with HSP70 and a J-domain protein (JDP), HSP110 maintains protein folding and resolubilizes aggregates. Interestingly, HSP110 is vital for the HSP70/110/JDP-mediated disaggregation of amyloidogenic proteins implicated in neurodegenerative diseases (i.e., α-synuclein, HTT, and tau). However, despite its abundance, HSP110 remains still an enigmatic chaperone, and its functional spectrum is not very well understood. Of note, the disaggregation activity of neurodegenerative disease-associated amyloid fibrils showed both beneficial and detrimental outcomes in vivo. To gain a more comprehensive understanding of the chaperone HSP110 in vivo, we analyzed its role in neuronal proteostasis and neurodegeneration in C. elegans. Specifically, we investigated the role of HSP110 in the regulation of amyloid beta peptide (Aβ) aggregation using an established Aβ-C. elegans model that mimics Alzheimer's disease pathology. We generated a novel C. elegans model that over-expresses hsp-110 pan-neuronally, and we also depleted hsp-110 by RNAi-mediated knockdown. We assessed Aβ aggregation in vivo and in situ by fluorescence lifetime imaging. We found that hsp-110 over-expression exacerbated Aβ aggregation and appeared to reduce the conformational variability of the Aβ aggregates, whereas hsp-110 depletion reduced aggregation more significantly in the IL2 neurons, which marked the onset of Aβ aggregation. HSP-110 also plays a central role in growth and fertility as its over-expression compromises nematode physiology. In addition, we found that HSP-110 modulation affects the autophagy pathway. While hsp-110 over-expression impairs the autophagic flux, a depletion enhances it. Thus, HSP-110 regulates multiple nodes of the proteostasis network to control amyloid protein aggregation, disaggregation, and autophagic clearance.
{"title":"HSP110 is a modulator of amyloid beta (Aβ) aggregation and proteotoxicity.","authors":"Sabrina Montresor, Maria Lucia Pigazzini, Sudarson Baskaran, Mira Sleiman, Govinda Adhikari, Lukas Basilicata, Luca Secker, Natascha Jacob, Yara Ehlert, Anushree Kelkar, Gurleen Kaur Kalsi, Niraj Kulkarni, Paul Spellerberg, Janine Kirstein","doi":"10.1111/jnc.16214","DOIUrl":"https://doi.org/10.1111/jnc.16214","url":null,"abstract":"<p><p>Chaperones safeguard protein homeostasis by promoting folding and preventing aggregation. HSP110 is a cytosolic chaperone that functions as a nucleotide exchange factor for the HSP70 cycle. Together with HSP70 and a J-domain protein (JDP), HSP110 maintains protein folding and resolubilizes aggregates. Interestingly, HSP110 is vital for the HSP70/110/JDP-mediated disaggregation of amyloidogenic proteins implicated in neurodegenerative diseases (i.e., α-synuclein, HTT, and tau). However, despite its abundance, HSP110 remains still an enigmatic chaperone, and its functional spectrum is not very well understood. Of note, the disaggregation activity of neurodegenerative disease-associated amyloid fibrils showed both beneficial and detrimental outcomes in vivo. To gain a more comprehensive understanding of the chaperone HSP110 in vivo, we analyzed its role in neuronal proteostasis and neurodegeneration in C. elegans. Specifically, we investigated the role of HSP110 in the regulation of amyloid beta peptide (Aβ) aggregation using an established Aβ-C. elegans model that mimics Alzheimer's disease pathology. We generated a novel C. elegans model that over-expresses hsp-110 pan-neuronally, and we also depleted hsp-110 by RNAi-mediated knockdown. We assessed Aβ aggregation in vivo and in situ by fluorescence lifetime imaging. We found that hsp-110 over-expression exacerbated Aβ aggregation and appeared to reduce the conformational variability of the Aβ aggregates, whereas hsp-110 depletion reduced aggregation more significantly in the IL2 neurons, which marked the onset of Aβ aggregation. HSP-110 also plays a central role in growth and fertility as its over-expression compromises nematode physiology. In addition, we found that HSP-110 modulation affects the autophagy pathway. While hsp-110 over-expression impairs the autophagic flux, a depletion enhances it. Thus, HSP-110 regulates multiple nodes of the proteostasis network to control amyloid protein aggregation, disaggregation, and autophagic clearance.</p>","PeriodicalId":16527,"journal":{"name":"Journal of Neurochemistry","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142046826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Christopher Wolff, Dorit John, Ulrike Winkler, Luise Hochmuth, Johannes Hirrlinger, Susanne Köhler
Astrocytes constitute a heterogeneous cell population within the brain, contributing crucially to brain homeostasis and playing an important role in overall brain function. Their function and metabolism are not only regulated by local signals, for example, from nearby neurons, but also by long-range signals such as hormones. Thus, two prominent hormones primarily known for regulating the energy balance of the whole organism, insulin, and leptin, have been reported to also impact astrocytes within the brain. In this study, we investigated the acute regulation of astrocytic metabolism by these hormones in cultured astrocytes prepared from the mouse cortex and hypothalamus, a pivotal region in the context of nutritional regulation. Utilizing genetically encoded, fluorescent nanosensors, the cytosolic concentrations of glucose, lactate, and ATP, along with glycolytic rate and the NADH/NAD+ redox state were measured. Under basal conditions, differences between the two populations of astrocytes were observed for glucose and lactate concentrations as well as the glycolytic rate. Additionally, astrocytic metabolism responded to insulin and leptin in both brain regions, with some unique characteristics for each cell population. Finally, both hormones influenced how cells responded to elevated extracellular levels of potassium ions, a common indicator of neuronal activity. In summary, our study provides evidence that insulin and leptin acutely regulate astrocytic metabolism within minutes. Additionally, while astrocytes from the hypothalamus and cortex share similarities in their metabolism, they also exhibit distinct properties, further underscoring the growing recognition of astrocyte heterogeneity.
星形胶质细胞是大脑中的一个异质性细胞群,对大脑的平衡起着至关重要的作用,并在大脑的整体功能中扮演着重要角色。星形胶质细胞的功能和新陈代谢不仅受附近神经元等局部信号的调节,还受激素等远距离信号的调节。因此,两种主要调节整个机体能量平衡的重要激素--胰岛素和瘦素,据报道也会影响脑内的星形胶质细胞。在这项研究中,我们研究了这些激素对小鼠大脑皮层和下丘脑(营养调节的关键区域)中培养的星形胶质细胞新陈代谢的急性调节。利用基因编码的荧光纳米传感器,测量了细胞膜中葡萄糖、乳酸和 ATP 的浓度,以及糖酵解率和 NADH/NAD+ 氧化还原状态。在基础条件下,观察到两组星形胶质细胞的葡萄糖和乳酸浓度以及糖酵解率存在差异。此外,两个脑区的星形胶质细胞代谢对胰岛素和瘦素都有反应,每个细胞群都有一些独特的特征。最后,这两种激素都会影响细胞对细胞外钾离子水平升高的反应,而钾离子是神经元活动的常见指标。总之,我们的研究提供了证据,证明胰岛素和瘦素可在几分钟内调节星形胶质细胞的新陈代谢。此外,虽然下丘脑和大脑皮层的星形胶质细胞在新陈代谢方面有相似之处,但它们也表现出不同的特性,这进一步强调了人们对星形胶质细胞异质性的日益认识。
{"title":"Insulin and leptin acutely modulate the energy metabolism of primary hypothalamic and cortical astrocytes.","authors":"Christopher Wolff, Dorit John, Ulrike Winkler, Luise Hochmuth, Johannes Hirrlinger, Susanne Köhler","doi":"10.1111/jnc.16211","DOIUrl":"https://doi.org/10.1111/jnc.16211","url":null,"abstract":"<p><p>Astrocytes constitute a heterogeneous cell population within the brain, contributing crucially to brain homeostasis and playing an important role in overall brain function. Their function and metabolism are not only regulated by local signals, for example, from nearby neurons, but also by long-range signals such as hormones. Thus, two prominent hormones primarily known for regulating the energy balance of the whole organism, insulin, and leptin, have been reported to also impact astrocytes within the brain. In this study, we investigated the acute regulation of astrocytic metabolism by these hormones in cultured astrocytes prepared from the mouse cortex and hypothalamus, a pivotal region in the context of nutritional regulation. Utilizing genetically encoded, fluorescent nanosensors, the cytosolic concentrations of glucose, lactate, and ATP, along with glycolytic rate and the NADH/NAD<sup>+</sup> redox state were measured. Under basal conditions, differences between the two populations of astrocytes were observed for glucose and lactate concentrations as well as the glycolytic rate. Additionally, astrocytic metabolism responded to insulin and leptin in both brain regions, with some unique characteristics for each cell population. Finally, both hormones influenced how cells responded to elevated extracellular levels of potassium ions, a common indicator of neuronal activity. In summary, our study provides evidence that insulin and leptin acutely regulate astrocytic metabolism within minutes. Additionally, while astrocytes from the hypothalamus and cortex share similarities in their metabolism, they also exhibit distinct properties, further underscoring the growing recognition of astrocyte heterogeneity.</p>","PeriodicalId":16527,"journal":{"name":"Journal of Neurochemistry","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142036057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Oligodendrocytes, the myelin-producing cells in the central nervous system (CNS), are crucial for rapid action potential conduction and neuronal communication. While extensively studied for their roles in neuronal support and axonal insulation, their involvement in pain modulation is an emerging research area. This review explores the interplay between oligodendrocytes, myelination, and pain, focusing on neuropathic pain following peripheral nerve injury, spinal cord injury (SCI), chemotherapy, and HIV infection. Studies indicate that a decrease in oligodendrocytes and increased cytokine production by oligodendroglia in response to injury can induce or exacerbate pain. An increase in endogenous oligodendrocyte precursor cells (OPCs) may be a compensatory response to repair damaged oligodendrocytes. Exogenous OPC transplantation shows promise in alleviating SCI-induced neuropathic pain and enhancing remyelination. Additionally, oligodendrocyte apoptosis in brain regions such as the medial prefrontal cortex is linked to opioid-induced hyperalgesia, highlighting their role in central pain mechanisms. Chemotherapeutic agents disrupt oligodendrocyte differentiation, leading to persistent pain, while HIV-associated neuropathy involves up-regulation of oligodendrocyte lineage cell markers. These findings underscore the multifaceted roles of oligodendrocytes in pain pathways, suggesting that targeting myelination processes could offer new therapeutic strategies for chronic pain management. Further research should elucidate the underlying molecular mechanisms to develop effective pain treatments.
{"title":"Unraveling the role of oligodendrocytes and myelin in pain.","authors":"Woojin Kim, María Cecilia Angulo","doi":"10.1111/jnc.16206","DOIUrl":"https://doi.org/10.1111/jnc.16206","url":null,"abstract":"<p><p>Oligodendrocytes, the myelin-producing cells in the central nervous system (CNS), are crucial for rapid action potential conduction and neuronal communication. While extensively studied for their roles in neuronal support and axonal insulation, their involvement in pain modulation is an emerging research area. This review explores the interplay between oligodendrocytes, myelination, and pain, focusing on neuropathic pain following peripheral nerve injury, spinal cord injury (SCI), chemotherapy, and HIV infection. Studies indicate that a decrease in oligodendrocytes and increased cytokine production by oligodendroglia in response to injury can induce or exacerbate pain. An increase in endogenous oligodendrocyte precursor cells (OPCs) may be a compensatory response to repair damaged oligodendrocytes. Exogenous OPC transplantation shows promise in alleviating SCI-induced neuropathic pain and enhancing remyelination. Additionally, oligodendrocyte apoptosis in brain regions such as the medial prefrontal cortex is linked to opioid-induced hyperalgesia, highlighting their role in central pain mechanisms. Chemotherapeutic agents disrupt oligodendrocyte differentiation, leading to persistent pain, while HIV-associated neuropathy involves up-regulation of oligodendrocyte lineage cell markers. These findings underscore the multifaceted roles of oligodendrocytes in pain pathways, suggesting that targeting myelination processes could offer new therapeutic strategies for chronic pain management. Further research should elucidate the underlying molecular mechanisms to develop effective pain treatments.</p>","PeriodicalId":16527,"journal":{"name":"Journal of Neurochemistry","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142004487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Oligodendrocyte progenitor cells (OPCs) differentiation into oligodendrocytes (OLs) and subsequent myelination are two closely coordinated yet differentially regulated steps for myelin formation and repair in the CNS. Previously thought as an inhibitory factor by activating Wnt/beta-catenin signaling, we and others have demonstrated that the Transcription factor 7-like 2 (TCF7l2) promotes OL differentiation independent of Wnt/beta-catenin signaling activation. However, it remains elusive if TCF7l2 directly controls CNS myelination separating from its role in upstream oligodendrocyte differentiation. This is partially because of the lack of genetic animal models that could tease out CNS myelination from upstream OL differentiation. Here, we report that constitutively depleting TCF7l2 transiently inhibited oligodendrocyte differentiation during early postnatal development, but it impaired CNS myelination in the long term in adult mice. Using time-conditional and developmental-stage-specific genetic approaches, we further showed that depleting TCF7l2 in already differentiated OLs did not impact myelin protein gene expression nor oligodendroglial populations, instead, it perturbed CNS myelination in the adult. Therefore, our data convincingly demonstrate the crucial role of TCF7l2 in regulating CNS myelination independent of its role in upstream oligodendrocyte differentiation.
{"title":"Transcription factor 7-like 2 (TCF7l2) regulates CNS myelination separating from its role in upstream oligodendrocyte differentiation.","authors":"Sheng Zhang, Meina Zhu, Zhaohui Lan, Fuzheng Guo","doi":"10.1111/jnc.16208","DOIUrl":"https://doi.org/10.1111/jnc.16208","url":null,"abstract":"<p><p>Oligodendrocyte progenitor cells (OPCs) differentiation into oligodendrocytes (OLs) and subsequent myelination are two closely coordinated yet differentially regulated steps for myelin formation and repair in the CNS. Previously thought as an inhibitory factor by activating Wnt/beta-catenin signaling, we and others have demonstrated that the Transcription factor 7-like 2 (TCF7l2) promotes OL differentiation independent of Wnt/beta-catenin signaling activation. However, it remains elusive if TCF7l2 directly controls CNS myelination separating from its role in upstream oligodendrocyte differentiation. This is partially because of the lack of genetic animal models that could tease out CNS myelination from upstream OL differentiation. Here, we report that constitutively depleting TCF7l2 transiently inhibited oligodendrocyte differentiation during early postnatal development, but it impaired CNS myelination in the long term in adult mice. Using time-conditional and developmental-stage-specific genetic approaches, we further showed that depleting TCF7l2 in already differentiated OLs did not impact myelin protein gene expression nor oligodendroglial populations, instead, it perturbed CNS myelination in the adult. Therefore, our data convincingly demonstrate the crucial role of TCF7l2 in regulating CNS myelination independent of its role in upstream oligodendrocyte differentiation.</p>","PeriodicalId":16527,"journal":{"name":"Journal of Neurochemistry","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142008923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
My Forsberg, Dinna Zhou, Shadi Jalali, Giorgia Faravelli, Henrik Seth, Andreas Björefeldt, Eric Hanse
It is well recognized that changes in the extracellular concentration of calcium ions influence the excitability of neurons, yet what mechanism(s) mediate these effects is still a matter of debate. Using patch-clamp recordings from rat hippocampal CA1 pyramidal neurons, we examined the contribution of G-proteins and intracellular calcium-dependent signaling mechanisms to changes in intrinsic excitability evoked by altering the extracellular calcium concentration from physiological (1.2 mM) to a commonly used experimental (2 mM) level. We find that the inhibitory effect on intrinsic excitability of calcium ions is mainly expressed as an increased threshold for action potential firing (with no significant effect on resting membrane potential) that is not blocked by either the G-protein inhibitor GDPβS or the calcium chelator BAPTA. Our results therefore argue that in the concentration range studied, G-protein coupled calcium-sensing receptors, non-selective cation conductances, and intracellular calcium signaling pathways are not involved in mediating the effect of extracellular calcium ions on intrinsic excitability. Analysis of the derivative of the action potential, dV/dt versus membrane potential, indicates a current shift towards more depolarized membrane potentials at the higher calcium concentration. Our results are thus consistent with a mechanism in which extracellular calcium ions act directly on the voltage-gated sodium channels by neutralizing negative charges on the extracellular surface of these channels to modulate the threshold for action potential activation.
众所周知,细胞外钙离子浓度的变化会影响神经元的兴奋性,但这些影响是由什么机制介导的仍是一个争论不休的问题。利用大鼠海马 CA1 锥体神经元的贴片钳记录,我们研究了 G 蛋白和细胞内钙离子依赖性信号机制对改变细胞外钙离子浓度(从生理水平(1.2 mM)到常用的实验水平(2 mM))所诱发的内在兴奋性变化的贡献。我们发现,钙离子对内在兴奋性的抑制作用主要表现为动作电位发射阈值的升高(对静息膜电位无明显影响),这种作用不会被 G 蛋白抑制剂 GDPβS 或钙螯合剂 BAPTA 所阻断。因此,我们的研究结果表明,在所研究的浓度范围内,G 蛋白偶联钙传感受体、非选择性阳离子传导和细胞内钙信号途径并未参与介导细胞外钙离子对内在兴奋性的影响。对动作电位的导数 dV/dt 与膜电位的分析表明,在钙离子浓度较高时,电流转向更多的去极化膜电位。因此,我们的结果与细胞外钙离子通过中和这些通道细胞外表面的负电荷直接作用于电压门控钠通道以调节动作电位激活阈值的机制是一致的。
{"title":"Evaluation of mechanisms involved in regulation of intrinsic excitability by extracellular calcium in CA1 pyramidal neurons of rat.","authors":"My Forsberg, Dinna Zhou, Shadi Jalali, Giorgia Faravelli, Henrik Seth, Andreas Björefeldt, Eric Hanse","doi":"10.1111/jnc.16209","DOIUrl":"https://doi.org/10.1111/jnc.16209","url":null,"abstract":"<p><p>It is well recognized that changes in the extracellular concentration of calcium ions influence the excitability of neurons, yet what mechanism(s) mediate these effects is still a matter of debate. Using patch-clamp recordings from rat hippocampal CA1 pyramidal neurons, we examined the contribution of G-proteins and intracellular calcium-dependent signaling mechanisms to changes in intrinsic excitability evoked by altering the extracellular calcium concentration from physiological (1.2 mM) to a commonly used experimental (2 mM) level. We find that the inhibitory effect on intrinsic excitability of calcium ions is mainly expressed as an increased threshold for action potential firing (with no significant effect on resting membrane potential) that is not blocked by either the G-protein inhibitor GDPβS or the calcium chelator BAPTA. Our results therefore argue that in the concentration range studied, G-protein coupled calcium-sensing receptors, non-selective cation conductances, and intracellular calcium signaling pathways are not involved in mediating the effect of extracellular calcium ions on intrinsic excitability. Analysis of the derivative of the action potential, dV/dt versus membrane potential, indicates a current shift towards more depolarized membrane potentials at the higher calcium concentration. Our results are thus consistent with a mechanism in which extracellular calcium ions act directly on the voltage-gated sodium channels by neutralizing negative charges on the extracellular surface of these channels to modulate the threshold for action potential activation.</p>","PeriodicalId":16527,"journal":{"name":"Journal of Neurochemistry","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142008922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sabrin Haddad, Cornelia Ablinger, Ruslan Stanika, Manuel Hessenberger, Marta Campiglio, Nadine J Ortner, Petronel Tuluc, Gerald J Obermair
α2δ proteins serve as auxiliary subunits of voltage-gated calcium channels and regulate channel membrane expression and current properties. Besides their channel function, α2δ proteins regulate synapse formation, differentiation, and synaptic wiring. Considering these important functions, it is not surprising that CACNA2D1-4, the genes encoding for α2δ-1 to -4 isoforms, have been implicated in neurological, neurodevelopmental, and neuropsychiatric disorders. Mutations in CACNA2D2 have been associated with developmental and epileptic encephalopathy (DEE) and cerebellar atrophy. In our present study, we performed a detailed functional characterization of the p.R593P mutation in α2δ-2, a homozygous mutation previously identified in two siblings with DEE. Importantly, we analyzed both calcium channel-dependent as well as synaptic functions of α2δ-2. Our data show that the corresponding p.R596P mutation in mouse α2δ-2 drastically decreases membrane expression and synaptic targeting of α2δ-2. This defect correlates with altered biophysical properties of postsynaptic CaV1.3 channel but has no effect on presynaptic CaV2.1 channels upon heterologous expression in tsA201 cells. However, homologous expression of α2δ-2_R596P in primary cultures of hippocampal neurons affects the ability of α2δ-2 to induce a statistically significant increase in the presynaptic abundance of endogenous CaV2.1 channels and presynaptic calcium transients. Moreover, our data demonstrate that in addition to lowering membrane expression, the p.R596P mutation reduces the trans-synaptic recruitment of GABAA receptors and presynaptic synapsin clustering in glutamatergic synapses. Lastly, the α2δ-2_R596P reduces the amplitudes of glutamatergic miniature postsynaptic currents in transduced hippocampal neurons. Taken together, our data strongly link the human biallelic p.R593P mutation to the underlying severe neurodevelopmental disorder and highlight the importance of studying α2δ mutations not only in the context of channelopathies but also synaptopathies.
{"title":"A biallelic mutation in CACNA2D2 associated with developmental and epileptic encephalopathy affects calcium channel-dependent as well as synaptic functions of α<sub>2</sub>δ-2.","authors":"Sabrin Haddad, Cornelia Ablinger, Ruslan Stanika, Manuel Hessenberger, Marta Campiglio, Nadine J Ortner, Petronel Tuluc, Gerald J Obermair","doi":"10.1111/jnc.16197","DOIUrl":"https://doi.org/10.1111/jnc.16197","url":null,"abstract":"<p><p>α<sub>2</sub>δ proteins serve as auxiliary subunits of voltage-gated calcium channels and regulate channel membrane expression and current properties. Besides their channel function, α<sub>2</sub>δ proteins regulate synapse formation, differentiation, and synaptic wiring. Considering these important functions, it is not surprising that CACNA2D1-4, the genes encoding for α<sub>2</sub>δ-1 to -4 isoforms, have been implicated in neurological, neurodevelopmental, and neuropsychiatric disorders. Mutations in CACNA2D2 have been associated with developmental and epileptic encephalopathy (DEE) and cerebellar atrophy. In our present study, we performed a detailed functional characterization of the p.R593P mutation in α<sub>2</sub>δ-2, a homozygous mutation previously identified in two siblings with DEE. Importantly, we analyzed both calcium channel-dependent as well as synaptic functions of α<sub>2</sub>δ-2. Our data show that the corresponding p.R596P mutation in mouse α<sub>2</sub>δ-2 drastically decreases membrane expression and synaptic targeting of α<sub>2</sub>δ-2. This defect correlates with altered biophysical properties of postsynaptic Ca<sub>V</sub>1.3 channel but has no effect on presynaptic Ca<sub>V</sub>2.1 channels upon heterologous expression in tsA201 cells. However, homologous expression of α<sub>2</sub>δ-2_R596P in primary cultures of hippocampal neurons affects the ability of α<sub>2</sub>δ-2 to induce a statistically significant increase in the presynaptic abundance of endogenous Ca<sub>V</sub>2.1 channels and presynaptic calcium transients. Moreover, our data demonstrate that in addition to lowering membrane expression, the p.R596P mutation reduces the trans-synaptic recruitment of GABA<sub>A</sub> receptors and presynaptic synapsin clustering in glutamatergic synapses. Lastly, the α<sub>2</sub>δ-2_R596P reduces the amplitudes of glutamatergic miniature postsynaptic currents in transduced hippocampal neurons. Taken together, our data strongly link the human biallelic p.R593P mutation to the underlying severe neurodevelopmental disorder and highlight the importance of studying α<sub>2</sub>δ mutations not only in the context of channelopathies but also synaptopathies.</p>","PeriodicalId":16527,"journal":{"name":"Journal of Neurochemistry","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142004486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}