Pub Date : 2024-10-07Epub Date: 2024-07-05DOI: 10.1083/jcb.202312069
Jonathan T Vu, Katherine U Tavasoli, Connor J Sheedy, Soham P Chowdhury, Lori Mandjikian, Julien Bacal, Meghan A Morrissey, Chris D Richardson, Brooke M Gardner
Peroxisomes are membrane-bound organelles harboring metabolic enzymes. In humans, peroxisomes are required for normal development, yet the genes regulating peroxisome function remain unclear. We performed a genome-wide CRISPRi screen to identify novel factors involved in peroxisomal homeostasis. We found that inhibition of RNF146, an E3 ligase activated by poly(ADP-ribose), reduced the import of proteins into peroxisomes. RNF146-mediated loss of peroxisome import depended on the stabilization and activity of the poly(ADP-ribose) polymerases TNKS and TNKS2, which bind the peroxisomal membrane protein PEX14. We propose that RNF146 and TNKS/2 regulate peroxisome import efficiency by PARsylation of proteins at the peroxisome membrane. Interestingly, we found that the loss of peroxisomes increased TNKS/2 and RNF146-dependent degradation of non-peroxisomal substrates, including the β-catenin destruction complex component AXIN1, which was sufficient to alter the amplitude of β-catenin transcription. Together, these observations not only suggest previously undescribed roles for RNF146 in peroxisomal regulation but also a novel role in bridging peroxisome function with Wnt/β-catenin signaling during development.
{"title":"A genome-wide screen links peroxisome regulation with Wnt signaling through RNF146 and TNKS/2.","authors":"Jonathan T Vu, Katherine U Tavasoli, Connor J Sheedy, Soham P Chowdhury, Lori Mandjikian, Julien Bacal, Meghan A Morrissey, Chris D Richardson, Brooke M Gardner","doi":"10.1083/jcb.202312069","DOIUrl":"10.1083/jcb.202312069","url":null,"abstract":"<p><p>Peroxisomes are membrane-bound organelles harboring metabolic enzymes. In humans, peroxisomes are required for normal development, yet the genes regulating peroxisome function remain unclear. We performed a genome-wide CRISPRi screen to identify novel factors involved in peroxisomal homeostasis. We found that inhibition of RNF146, an E3 ligase activated by poly(ADP-ribose), reduced the import of proteins into peroxisomes. RNF146-mediated loss of peroxisome import depended on the stabilization and activity of the poly(ADP-ribose) polymerases TNKS and TNKS2, which bind the peroxisomal membrane protein PEX14. We propose that RNF146 and TNKS/2 regulate peroxisome import efficiency by PARsylation of proteins at the peroxisome membrane. Interestingly, we found that the loss of peroxisomes increased TNKS/2 and RNF146-dependent degradation of non-peroxisomal substrates, including the β-catenin destruction complex component AXIN1, which was sufficient to alter the amplitude of β-catenin transcription. Together, these observations not only suggest previously undescribed roles for RNF146 in peroxisomal regulation but also a novel role in bridging peroxisome function with Wnt/β-catenin signaling during development.</p>","PeriodicalId":15211,"journal":{"name":"Journal of Cell Biology","volume":null,"pages":null},"PeriodicalIF":7.4,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11223164/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141534524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-07Epub Date: 2024-08-08DOI: 10.1083/jcb.202401024
Eline C Brombacher, Thiago A Patente, Alwin J van der Ham, Tijmen J A Moll, Frank Otto, Fenne W M Verheijen, Esther A Zaal, Arnoud H de Ru, Rayman T N Tjokrodirijo, Celia R Berkers, Peter A van Veelen, Bruno Guigas, Bart Everts
Dendritic cell (DC) activation and function are underpinned by profound changes in cellular metabolism. Several studies indicate that the ability of DCs to promote tolerance is dependent on catabolic metabolism. Yet the contribution of AMP-activated kinase (AMPK), a central energy sensor promoting catabolism, to DC tolerogenicity remains unknown. Here, we show that AMPK activation renders human monocyte-derived DCs tolerogenic as evidenced by an enhanced ability to drive differentiation of regulatory T cells, a process dependent on increased RALDH activity. This is accompanied by several metabolic changes, including increased breakdown of glycerophospholipids, enhanced mitochondrial fission-dependent fatty acid oxidation, and upregulated glucose catabolism. This metabolic rewiring is functionally important as we found interference with these metabolic processes to reduce to various degrees AMPK-induced RALDH activity as well as the tolerogenic capacity of moDCs. Altogether, our findings reveal a key role for AMPK signaling in shaping DC tolerogenicity and suggest AMPK as a target to direct DC-driven tolerogenic responses in therapeutic settings.
树突状细胞(DC)的活化和功能是由细胞代谢的深刻变化支撑的。一些研究表明,树突状细胞促进耐受的能力取决于分解代谢。然而,促进新陈代谢的中心能量传感器 AMPK 对 DC 耐受性的贡献仍然未知。在这里,我们发现 AMPK 激活可使人类单核细胞衍生的 DC 产生耐受性,这表现在驱动调节性 T 细胞分化的能力增强,而这一过程依赖于 RALDH 活性的增加。与此同时,新陈代谢也发生了一些变化,包括甘油磷脂分解增加、线粒体裂变依赖性脂肪酸氧化增强以及葡萄糖分解代谢上调。这种代谢重构在功能上非常重要,因为我们发现干扰这些代谢过程会在不同程度上降低 AMPK 诱导的 RALDH 活性以及 moDCs 的耐受能力。总之,我们的研究结果揭示了 AMPK 信号在形成直流耐受性中的关键作用,并建议将 AMPK 作为治疗环境中指导直流驱动的耐受性反应的靶点。
{"title":"AMPK activation induces RALDH+ tolerogenic dendritic cells by rewiring glucose and lipid metabolism.","authors":"Eline C Brombacher, Thiago A Patente, Alwin J van der Ham, Tijmen J A Moll, Frank Otto, Fenne W M Verheijen, Esther A Zaal, Arnoud H de Ru, Rayman T N Tjokrodirijo, Celia R Berkers, Peter A van Veelen, Bruno Guigas, Bart Everts","doi":"10.1083/jcb.202401024","DOIUrl":"10.1083/jcb.202401024","url":null,"abstract":"<p><p>Dendritic cell (DC) activation and function are underpinned by profound changes in cellular metabolism. Several studies indicate that the ability of DCs to promote tolerance is dependent on catabolic metabolism. Yet the contribution of AMP-activated kinase (AMPK), a central energy sensor promoting catabolism, to DC tolerogenicity remains unknown. Here, we show that AMPK activation renders human monocyte-derived DCs tolerogenic as evidenced by an enhanced ability to drive differentiation of regulatory T cells, a process dependent on increased RALDH activity. This is accompanied by several metabolic changes, including increased breakdown of glycerophospholipids, enhanced mitochondrial fission-dependent fatty acid oxidation, and upregulated glucose catabolism. This metabolic rewiring is functionally important as we found interference with these metabolic processes to reduce to various degrees AMPK-induced RALDH activity as well as the tolerogenic capacity of moDCs. Altogether, our findings reveal a key role for AMPK signaling in shaping DC tolerogenicity and suggest AMPK as a target to direct DC-driven tolerogenic responses in therapeutic settings.</p>","PeriodicalId":15211,"journal":{"name":"Journal of Cell Biology","volume":null,"pages":null},"PeriodicalIF":7.4,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11310580/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141901861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-07Epub Date: 2024-07-30DOI: 10.1083/jcb.202401140
Gabriel Escobedo, Yu Wu, Yuki Ogawa, Xiaoyun Ding, Matthew N Rasband
The evolution of ion channel clustering at nodes of Ranvier enabled the development of complex vertebrate nervous systems. At mammalian nodes, the K+ leak channels TRAAK and TREK-1 underlie membrane repolarization. Despite the molecular similarities between nodes and the axon initial segment (AIS), TRAAK and TREK-1 are reportedly node-specific, suggesting a unique clustering mechanism. However, we show that TRAAK and TREK-1 are enriched at both nodes and AIS through a common mechanism. We identified a motif near the C-terminus of TRAAK that is necessary and sufficient for its clustering. The motif first evolved among cartilaginous fish. Using AnkyrinG (AnkG) conditional knockout mice, CRISPR/Cas9-mediated disruption of AnkG, co-immunoprecipitation, and surface recruitment assays, we show that TRAAK forms a complex with AnkG and that AnkG is necessary for TRAAK's AIS and nodal clustering. In contrast, TREK-1's clustering requires TRAAK. Our results expand the repertoire of AIS and nodal ion channel clustering mechanisms and emphasize AnkG's central role in assembling excitable domains.
{"title":"An evolutionarily conserved AnkyrinG-dependent motif clusters axonal K2P K+ channels.","authors":"Gabriel Escobedo, Yu Wu, Yuki Ogawa, Xiaoyun Ding, Matthew N Rasband","doi":"10.1083/jcb.202401140","DOIUrl":"10.1083/jcb.202401140","url":null,"abstract":"<p><p>The evolution of ion channel clustering at nodes of Ranvier enabled the development of complex vertebrate nervous systems. At mammalian nodes, the K+ leak channels TRAAK and TREK-1 underlie membrane repolarization. Despite the molecular similarities between nodes and the axon initial segment (AIS), TRAAK and TREK-1 are reportedly node-specific, suggesting a unique clustering mechanism. However, we show that TRAAK and TREK-1 are enriched at both nodes and AIS through a common mechanism. We identified a motif near the C-terminus of TRAAK that is necessary and sufficient for its clustering. The motif first evolved among cartilaginous fish. Using AnkyrinG (AnkG) conditional knockout mice, CRISPR/Cas9-mediated disruption of AnkG, co-immunoprecipitation, and surface recruitment assays, we show that TRAAK forms a complex with AnkG and that AnkG is necessary for TRAAK's AIS and nodal clustering. In contrast, TREK-1's clustering requires TRAAK. Our results expand the repertoire of AIS and nodal ion channel clustering mechanisms and emphasize AnkG's central role in assembling excitable domains.</p>","PeriodicalId":15211,"journal":{"name":"Journal of Cell Biology","volume":null,"pages":null},"PeriodicalIF":7.4,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11289519/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141792525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-07Epub Date: 2024-08-16DOI: 10.1083/jcb.202405175
Shashank Rai, Maria Szaruga, Aleksandra P Pitera, Anne Bertolotti
The integrated stress response (ISR) is a vital signaling pathway initiated by four kinases, PERK, GCN2, HRI and PKR, that ensure cellular resilience and protect cells from challenges. Here, we investigated whether increasing ISR signaling could rescue diabetes-like phenotypes in a mouse model of diet-induced obesity (DIO). We show that the orally available and clinically approved GCN2 activator halofuginone (HF) can activate the ISR in mouse tissues. We found that daily oral administration of HF increases glucose tolerance whilst reducing weight gain, insulin resistance, and serum insulin in DIO mice. Conversely, the ISR inhibitor GSK2656157, used at low doses to optimize its selectivity, aggravates glucose intolerance in DIO mice. Whilst loss of function mutations in mice and humans have revealed that PERK is the essential ISR kinase that protects from diabetes, our work demonstrates the therapeutic value of increasing ISR signaling by activating the related kinase GCN2 to reduce diabetes phenotypes in a DIO mouse model.
综合应激反应(ISR)是由四种激酶(PERK、GCN2、HRI 和 PKR)启动的重要信号通路,可确保细胞恢复能力并保护细胞免受挑战。在这里,我们研究了增加 ISR 信号传导是否能挽救饮食诱导肥胖(DIO)小鼠模型中的糖尿病样表型。我们的研究表明,可口服且已获临床批准的 GCN2 激活剂卤夫酮 (HF) 能激活小鼠组织中的 ISR。我们发现,每天口服 HF 可增加葡萄糖耐量,同时减少 DIO 小鼠的体重增加、胰岛素抵抗和血清胰岛素。相反,低剂量使用以优化其选择性的 ISR 抑制剂 GSK2656157 会加重 DIO 小鼠的葡萄糖耐受性。虽然小鼠和人类的功能缺失突变揭示了 PERK 是防止糖尿病的重要 ISR 激酶,但我们的工作证明了通过激活相关激酶 GCN2 来增加 ISR 信号的治疗价值,从而减少 DIO 小鼠模型中的糖尿病表型。
{"title":"Integrated stress response activator halofuginone protects mice from diabetes-like phenotypes.","authors":"Shashank Rai, Maria Szaruga, Aleksandra P Pitera, Anne Bertolotti","doi":"10.1083/jcb.202405175","DOIUrl":"10.1083/jcb.202405175","url":null,"abstract":"<p><p>The integrated stress response (ISR) is a vital signaling pathway initiated by four kinases, PERK, GCN2, HRI and PKR, that ensure cellular resilience and protect cells from challenges. Here, we investigated whether increasing ISR signaling could rescue diabetes-like phenotypes in a mouse model of diet-induced obesity (DIO). We show that the orally available and clinically approved GCN2 activator halofuginone (HF) can activate the ISR in mouse tissues. We found that daily oral administration of HF increases glucose tolerance whilst reducing weight gain, insulin resistance, and serum insulin in DIO mice. Conversely, the ISR inhibitor GSK2656157, used at low doses to optimize its selectivity, aggravates glucose intolerance in DIO mice. Whilst loss of function mutations in mice and humans have revealed that PERK is the essential ISR kinase that protects from diabetes, our work demonstrates the therapeutic value of increasing ISR signaling by activating the related kinase GCN2 to reduce diabetes phenotypes in a DIO mouse model.</p>","PeriodicalId":15211,"journal":{"name":"Journal of Cell Biology","volume":null,"pages":null},"PeriodicalIF":7.4,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11329777/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141988072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-07Epub Date: 2024-07-09DOI: 10.1083/jcb.202311191
Min Zhu, Han Xu, Yulei Jin, Xiaoxu Kong, Bingkuan Xu, Yinghui Liu, Haijia Yu
Synaptotagmin-1 (Syt1) is a calcium sensor that regulates synaptic vesicle fusion in synchronous neurotransmitter release. Syt1 interacts with negatively charged lipids and the SNARE complex to control the fusion event. However, it remains incompletely understood how Syt1 mediates Ca2+-trigged synaptic vesicle fusion. Here, we discovered that Syt1 undergoes liquid-liquid phase separation (LLPS) to form condensates both in vitro and in living cells. Syt1 condensates play a role in vesicle attachment to the PM and efficiently recruit SNAREs and complexin, which may facilitate the downstream synaptic vesicle fusion. We observed that Syt1 condensates undergo a liquid-to-gel-like phase transition, reflecting the formation of Syt1 oligomers. The phase transition can be blocked or reversed by Ca2+, confirming the essential role of Ca2+ in Syt1 oligomer disassembly. Finally, we showed that the Syt1 mutations causing Syt1-associated neurodevelopmental disorder impair the Ca2+-driven phase transition. These findings reveal that Syt1 undergoes LLPS and a Ca2+-sensitive phase transition, providing new insights into Syt1-mediated vesicle fusion.
{"title":"Synaptotagmin-1 undergoes phase separation to regulate its calcium-sensitive oligomerization.","authors":"Min Zhu, Han Xu, Yulei Jin, Xiaoxu Kong, Bingkuan Xu, Yinghui Liu, Haijia Yu","doi":"10.1083/jcb.202311191","DOIUrl":"10.1083/jcb.202311191","url":null,"abstract":"<p><p>Synaptotagmin-1 (Syt1) is a calcium sensor that regulates synaptic vesicle fusion in synchronous neurotransmitter release. Syt1 interacts with negatively charged lipids and the SNARE complex to control the fusion event. However, it remains incompletely understood how Syt1 mediates Ca2+-trigged synaptic vesicle fusion. Here, we discovered that Syt1 undergoes liquid-liquid phase separation (LLPS) to form condensates both in vitro and in living cells. Syt1 condensates play a role in vesicle attachment to the PM and efficiently recruit SNAREs and complexin, which may facilitate the downstream synaptic vesicle fusion. We observed that Syt1 condensates undergo a liquid-to-gel-like phase transition, reflecting the formation of Syt1 oligomers. The phase transition can be blocked or reversed by Ca2+, confirming the essential role of Ca2+ in Syt1 oligomer disassembly. Finally, we showed that the Syt1 mutations causing Syt1-associated neurodevelopmental disorder impair the Ca2+-driven phase transition. These findings reveal that Syt1 undergoes LLPS and a Ca2+-sensitive phase transition, providing new insights into Syt1-mediated vesicle fusion.</p>","PeriodicalId":15211,"journal":{"name":"Journal of Cell Biology","volume":null,"pages":null},"PeriodicalIF":7.4,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11232894/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141558843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-07Epub Date: 2024-07-30DOI: 10.1083/jcb.202402016
Jinglin Li, Qiuyuan Yin, Nan Xuan, Qiwen Gan, Chaolian Liu, Qian Zhang, Mei Yang, Chonglin Yang
Lysosome-related organelles (LROs) are specialized lysosomes with cell type-specific roles in organismal homeostasis. Dysregulation of LROs leads to many human disorders, but the mechanisms underlying their biogenesis are not fully understood. Here, we identify a group of LYSMD proteins as evolutionarily conserved regulators of LROs. In Caenorhabditis elegans, mutations of LMD-2, a LysM domain-containing protein, reduce the levels of the Rab32 GTPase ortholog GLO-1 on intestine-specific LROs, the gut granules, leading to their abnormal enlargement and defective biogenesis. LMD-2 interacts with GLO-3, a subunit of GLO-1 guanine nucleotide exchange factor (GEF), thereby promoting GLO-1 activation. Mammalian homologs of LMD-2, LYSMD1, and LYSMD2 can functionally replace LMD-2 in C. elegans. In mammals, LYSMD1/2 physically interact with the HPS1 subunit of BLOC-3, the GEF of Rab32/38, thus promoting Rab32 activation. Inactivation of both LYSMD1 and LYSMD2 reduces Rab32 activation, causing melanosome enlargement and decreased melanin production in mouse melanoma cells. These findings provide important mechanistic insights into LRO biogenesis and functions.
{"title":"LYSMD proteins promote activation of Rab32-family GTPases for lysosome-related organelle biogenesis.","authors":"Jinglin Li, Qiuyuan Yin, Nan Xuan, Qiwen Gan, Chaolian Liu, Qian Zhang, Mei Yang, Chonglin Yang","doi":"10.1083/jcb.202402016","DOIUrl":"10.1083/jcb.202402016","url":null,"abstract":"<p><p>Lysosome-related organelles (LROs) are specialized lysosomes with cell type-specific roles in organismal homeostasis. Dysregulation of LROs leads to many human disorders, but the mechanisms underlying their biogenesis are not fully understood. Here, we identify a group of LYSMD proteins as evolutionarily conserved regulators of LROs. In Caenorhabditis elegans, mutations of LMD-2, a LysM domain-containing protein, reduce the levels of the Rab32 GTPase ortholog GLO-1 on intestine-specific LROs, the gut granules, leading to their abnormal enlargement and defective biogenesis. LMD-2 interacts with GLO-3, a subunit of GLO-1 guanine nucleotide exchange factor (GEF), thereby promoting GLO-1 activation. Mammalian homologs of LMD-2, LYSMD1, and LYSMD2 can functionally replace LMD-2 in C. elegans. In mammals, LYSMD1/2 physically interact with the HPS1 subunit of BLOC-3, the GEF of Rab32/38, thus promoting Rab32 activation. Inactivation of both LYSMD1 and LYSMD2 reduces Rab32 activation, causing melanosome enlargement and decreased melanin production in mouse melanoma cells. These findings provide important mechanistic insights into LRO biogenesis and functions.</p>","PeriodicalId":15211,"journal":{"name":"Journal of Cell Biology","volume":null,"pages":null},"PeriodicalIF":7.4,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11289520/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141792526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-07Epub Date: 2024-08-05DOI: 10.1083/jcb.202403179
Miharu Maeda, Masashi Arakawa, Yukie Komatsu, Kota Saito
Small GTPases are essential in various cellular signaling pathways, and detecting their activation within living cells is crucial for understanding cellular processes. The current methods for detecting GTPase activation using fluorescent proteins rely on the interaction between the GTPase and its effector. Consequently, these methods are not applicable to factors, such as Sar1, where the effector also functions as a GTPase-activating protein. Here, we present a novel method, the Small GTPase ActIvitY ANalyzing (SAIYAN) system, for detecting the activation of endogenous small GTPases via fluorescent signals utilizing a split mNeonGreen system. We demonstrated Sar1 activation at the endoplasmic reticulum (ER) exit site and successfully detected its activation state in various cellular conditions. Utilizing the SAIYAN system in collagen-secreting cells, we discovered activated Sar1 localized both at the ER exit sites and ER-Golgi intermediate compartment (ERGIC) regions. Additionally, impaired collagen secretion confined the activated Sar1 at the ER exit sites, implying the importance of Sar1 activation through the ERGIC in collagen secretion.
{"title":"Small GTPase ActIvitY ANalyzing (SAIYAN) system: A method to detect GTPase activation in living cells.","authors":"Miharu Maeda, Masashi Arakawa, Yukie Komatsu, Kota Saito","doi":"10.1083/jcb.202403179","DOIUrl":"10.1083/jcb.202403179","url":null,"abstract":"<p><p>Small GTPases are essential in various cellular signaling pathways, and detecting their activation within living cells is crucial for understanding cellular processes. The current methods for detecting GTPase activation using fluorescent proteins rely on the interaction between the GTPase and its effector. Consequently, these methods are not applicable to factors, such as Sar1, where the effector also functions as a GTPase-activating protein. Here, we present a novel method, the Small GTPase ActIvitY ANalyzing (SAIYAN) system, for detecting the activation of endogenous small GTPases via fluorescent signals utilizing a split mNeonGreen system. We demonstrated Sar1 activation at the endoplasmic reticulum (ER) exit site and successfully detected its activation state in various cellular conditions. Utilizing the SAIYAN system in collagen-secreting cells, we discovered activated Sar1 localized both at the ER exit sites and ER-Golgi intermediate compartment (ERGIC) regions. Additionally, impaired collagen secretion confined the activated Sar1 at the ER exit sites, implying the importance of Sar1 activation through the ERGIC in collagen secretion.</p>","PeriodicalId":15211,"journal":{"name":"Journal of Cell Biology","volume":null,"pages":null},"PeriodicalIF":7.4,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11303508/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141889350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-07Epub Date: 2024-08-13DOI: 10.1083/jcb.202404038
Carolyn M Ott, Sandii Constable, Tri M Nguyen, Kevin White, Wei-Chung Allen Lee, Jennifer Lippincott-Schwartz, Saikat Mukhopadhyay
Primary cilia on granule cell neuron progenitors in the developing cerebellum detect sonic hedgehog to facilitate proliferation. Following differentiation, cerebellar granule cells become the most abundant neuronal cell type in the brain. While granule cell cilia are essential during early developmental stages, they become infrequent upon maturation. Here, we provide nanoscopic resolution of cilia in situ using large-scale electron microscopy volumes and immunostaining of mouse cerebella. In many granule cells, we found intracellular cilia, concealed from the external environment. Cilia were disassembled in differentiating granule cell neurons-in a process we call cilia deconstruction-distinct from premitotic cilia resorption in proliferating progenitors. In differentiating granule cells, cilia deconstruction involved unique disassembly intermediates, and, as maturation progressed, mother centriolar docking at the plasma membrane. Unlike ciliated neurons in other brain regions, our results show the deconstruction of concealed cilia in differentiating granule cells, which might prevent mitogenic hedgehog responsiveness. Ciliary deconstruction could be paradigmatic of cilia removal during differentiation in other tissues.
{"title":"Permanent deconstruction of intracellular primary cilia in differentiating granule cell neurons.","authors":"Carolyn M Ott, Sandii Constable, Tri M Nguyen, Kevin White, Wei-Chung Allen Lee, Jennifer Lippincott-Schwartz, Saikat Mukhopadhyay","doi":"10.1083/jcb.202404038","DOIUrl":"10.1083/jcb.202404038","url":null,"abstract":"<p><p>Primary cilia on granule cell neuron progenitors in the developing cerebellum detect sonic hedgehog to facilitate proliferation. Following differentiation, cerebellar granule cells become the most abundant neuronal cell type in the brain. While granule cell cilia are essential during early developmental stages, they become infrequent upon maturation. Here, we provide nanoscopic resolution of cilia in situ using large-scale electron microscopy volumes and immunostaining of mouse cerebella. In many granule cells, we found intracellular cilia, concealed from the external environment. Cilia were disassembled in differentiating granule cell neurons-in a process we call cilia deconstruction-distinct from premitotic cilia resorption in proliferating progenitors. In differentiating granule cells, cilia deconstruction involved unique disassembly intermediates, and, as maturation progressed, mother centriolar docking at the plasma membrane. Unlike ciliated neurons in other brain regions, our results show the deconstruction of concealed cilia in differentiating granule cells, which might prevent mitogenic hedgehog responsiveness. Ciliary deconstruction could be paradigmatic of cilia removal during differentiation in other tissues.</p>","PeriodicalId":15211,"journal":{"name":"Journal of Cell Biology","volume":null,"pages":null},"PeriodicalIF":7.4,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11320830/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141975791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-07Epub Date: 2024-06-27DOI: 10.1083/jcb.202402114
Alison C E Wirshing, Claudia A Petrucco, Daniel J Lew
Aureobasidium pullulans is a ubiquitous polymorphic black yeast with industrial and agricultural applications. It has recently gained attention amongst cell biologists for its unconventional mode of proliferation in which multinucleate yeast cells make multiple buds within a single cell cycle. Here, we combine a chemical transformation method with genome-targeted homologous recombination to yield ∼60 transformants/μg of DNA in just 3 days. This protocol is simple, inexpensive, and requires no specialized equipment. We also describe vectors with codon-optimized green and red fluorescent proteins for A. pullulans and use these tools to explore novel cell biology. Quantitative imaging of a strain expressing cytosolic and nuclear markers showed that although the nuclear number varies considerably among cells of similar volume, total nuclear volume scales with cell volume over an impressive 70-fold size range. The protocols and tools described here expand the toolkit for A. pullulans biologists and will help researchers address the many other puzzles posed by this polyextremotolerant and morphologically plastic organism.
{"title":"Chemical transformation of the multibudding yeast, Aureobasidium pullulans.","authors":"Alison C E Wirshing, Claudia A Petrucco, Daniel J Lew","doi":"10.1083/jcb.202402114","DOIUrl":"10.1083/jcb.202402114","url":null,"abstract":"<p><p>Aureobasidium pullulans is a ubiquitous polymorphic black yeast with industrial and agricultural applications. It has recently gained attention amongst cell biologists for its unconventional mode of proliferation in which multinucleate yeast cells make multiple buds within a single cell cycle. Here, we combine a chemical transformation method with genome-targeted homologous recombination to yield ∼60 transformants/μg of DNA in just 3 days. This protocol is simple, inexpensive, and requires no specialized equipment. We also describe vectors with codon-optimized green and red fluorescent proteins for A. pullulans and use these tools to explore novel cell biology. Quantitative imaging of a strain expressing cytosolic and nuclear markers showed that although the nuclear number varies considerably among cells of similar volume, total nuclear volume scales with cell volume over an impressive 70-fold size range. The protocols and tools described here expand the toolkit for A. pullulans biologists and will help researchers address the many other puzzles posed by this polyextremotolerant and morphologically plastic organism.</p>","PeriodicalId":15211,"journal":{"name":"Journal of Cell Biology","volume":null,"pages":null},"PeriodicalIF":7.4,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11211067/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141457102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-07Epub Date: 2024-07-22DOI: 10.1083/jcb.202306152
Jeffrey Y Lee, Dalia S Gala, Maria Kiourlappou, Julia Olivares-Abril, Jana Joha, Joshua S Titlow, Rita O Teodoro, Ilan Davis
The polarization of cells often involves the transport of specific mRNAs and their localized translation in distal projections. Neurons and glia are both known to contain long cytoplasmic processes, while localized transcripts have only been studied extensively in neurons, not glia, especially in intact nervous systems. Here, we predict 1,740 localized Drosophila glial transcripts by extrapolating from our meta-analysis of seven existing studies characterizing the localized transcriptomes and translatomes of synaptically associated mammalian glia. We demonstrate that the localization of mRNAs in mammalian glial projections strongly predicts the localization of their high-confidence Drosophila homologs in larval motor neuron-associated glial projections and are highly statistically enriched for genes associated with neurological diseases. We further show that some of these localized glial transcripts are specifically required in glia for structural plasticity at the nearby neuromuscular junction synapses. We conclude that peripheral glial mRNA localization is a common and conserved phenomenon and propose that it is likely to be functionally important in disease.
{"title":"Murine glial protrusion transcripts predict localized Drosophila glial mRNAs involved in plasticity.","authors":"Jeffrey Y Lee, Dalia S Gala, Maria Kiourlappou, Julia Olivares-Abril, Jana Joha, Joshua S Titlow, Rita O Teodoro, Ilan Davis","doi":"10.1083/jcb.202306152","DOIUrl":"10.1083/jcb.202306152","url":null,"abstract":"<p><p>The polarization of cells often involves the transport of specific mRNAs and their localized translation in distal projections. Neurons and glia are both known to contain long cytoplasmic processes, while localized transcripts have only been studied extensively in neurons, not glia, especially in intact nervous systems. Here, we predict 1,740 localized Drosophila glial transcripts by extrapolating from our meta-analysis of seven existing studies characterizing the localized transcriptomes and translatomes of synaptically associated mammalian glia. We demonstrate that the localization of mRNAs in mammalian glial projections strongly predicts the localization of their high-confidence Drosophila homologs in larval motor neuron-associated glial projections and are highly statistically enriched for genes associated with neurological diseases. We further show that some of these localized glial transcripts are specifically required in glia for structural plasticity at the nearby neuromuscular junction synapses. We conclude that peripheral glial mRNA localization is a common and conserved phenomenon and propose that it is likely to be functionally important in disease.</p>","PeriodicalId":15211,"journal":{"name":"Journal of Cell Biology","volume":null,"pages":null},"PeriodicalIF":7.4,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11262410/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141734187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}