M. S. Simpson, Heidi De Luca, Sarah Cauthorn, P. Luong, N. Udeshi, Tanya Svinkina, Stefanie S. Schmieder, Steve Carr, Michael J. Grey, W. Lencer
IRE1α is an endoplasmic reticulum (ER) sensor that recognizes misfolded proteins to induce the unfolded protein response (UPR). We studied cholera toxin (CTx), which invades the ER and activates IRE1α in host cells, to understand how unfolded proteins are recognized. Proximity labeling colocalized the enzymatic and metastable A1 segment of CTx (CTxA1) with IRE1α in live cells, where we also found that CTx-induced IRE1α activation enhanced toxicity. In vitro, CTxA1 bound the IRE1α lumenal domain (IRE1αLD), but global unfolding was not required. Rather, the IRE1αLD recognized a seven-residue motif within an edge β-strand of CTxA1 that must locally unfold for binding. Binding mapped to a pocket on IRE1αLD normally occupied by a segment of the IRE1α C-terminal flexible loop implicated in IRE1α oligomerization. Mutation of the CTxA1 recognition motif blocked CTx-induced IRE1α activation in live cells, thus linking the binding event with IRE1α signal transduction and induction of the UPR.
{"title":"IRE1α recognizes a structural motif in cholera toxin to activate an unfolded protein response.","authors":"M. S. Simpson, Heidi De Luca, Sarah Cauthorn, P. Luong, N. Udeshi, Tanya Svinkina, Stefanie S. Schmieder, Steve Carr, Michael J. Grey, W. Lencer","doi":"10.1083/jcb.202402062","DOIUrl":"https://doi.org/10.1083/jcb.202402062","url":null,"abstract":"IRE1α is an endoplasmic reticulum (ER) sensor that recognizes misfolded proteins to induce the unfolded protein response (UPR). We studied cholera toxin (CTx), which invades the ER and activates IRE1α in host cells, to understand how unfolded proteins are recognized. Proximity labeling colocalized the enzymatic and metastable A1 segment of CTx (CTxA1) with IRE1α in live cells, where we also found that CTx-induced IRE1α activation enhanced toxicity. In vitro, CTxA1 bound the IRE1α lumenal domain (IRE1αLD), but global unfolding was not required. Rather, the IRE1αLD recognized a seven-residue motif within an edge β-strand of CTxA1 that must locally unfold for binding. Binding mapped to a pocket on IRE1αLD normally occupied by a segment of the IRE1α C-terminal flexible loop implicated in IRE1α oligomerization. Mutation of the CTxA1 recognition motif blocked CTx-induced IRE1α activation in live cells, thus linking the binding event with IRE1α signal transduction and induction of the UPR.","PeriodicalId":343306,"journal":{"name":"The Journal of Cell Biology","volume":"99 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140736044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiong and Sheng review recent advances in presynaptic mechanisms of neurodevelopmental disorders by focusing on impaired axonal transport of presynaptic cargos.
熊和盛以突触前载体的轴突运输受损为重点，回顾了神经发育障碍突触前机制的最新研究进展。
{"title":"Presynaptic perspective: Axonal transport defects in neurodevelopmental disorders","authors":"Gui-Jing Xiong, Zu-Hang Sheng","doi":"10.1083/jcb.202401145","DOIUrl":"https://doi.org/10.1083/jcb.202401145","url":null,"abstract":"Xiong and Sheng review recent advances in presynaptic mechanisms of neurodevelopmental disorders by focusing on impaired axonal transport of presynaptic cargos.","PeriodicalId":343306,"journal":{"name":"The Journal of Cell Biology","volume":"39 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140750936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-18DOI: 10.1101/2022.09.23.509043
Zihan Zhu, Isabelle Bécam, Corinne A. Tovey, Eugenie C. Yen, F. Bernard, A. Guichet, Paul T. Conduit
Microtubule nucleation is mediated by γ-tubulin ring complexes (γ-TuRCs). In most eukaryotes, a GCP4/5/4/6 “core” complex promotes γ-tubulin small complex (γ-TuSC) association to generate cytosolic γ-TuRCs. Unlike γ-TuSCs, however, this core complex is non-essential in various species and absent from budding yeasts. In Drosophila, Spindle defective-2 (Spd-2) and Centrosomin (Cnn) redundantly recruit γ-tubulin complexes to mitotic centrosomes. Here we show that Spd-2 recruits γ-TuRCs formed via the GCP4/5/4/6 core, but that Cnn can recruit γ-TuSCs directly via its well-conserved CM1 domain, similar to its homologues in budding yeast. When centrosomes fail to recruit γ-tubulin complexes, they still nucleate microtubules via the TOG domain protein Mini-spindles (Msps), but these microtubules have different dynamic properties. Our data therefore help explain the dispensability of the GCP4/5/4/6 core and highlight the robustness of centrosomes as microtubule organising centres. They also suggest that the dynamic properties of microtubules are influenced by how they were nucleated.
{"title":"Multifaceted modes of γ-tubulin complex recruitment and microtubule nucleation at mitotic centrosomes","authors":"Zihan Zhu, Isabelle Bécam, Corinne A. Tovey, Eugenie C. Yen, F. Bernard, A. Guichet, Paul T. Conduit","doi":"10.1101/2022.09.23.509043","DOIUrl":"https://doi.org/10.1101/2022.09.23.509043","url":null,"abstract":"Microtubule nucleation is mediated by γ-tubulin ring complexes (γ-TuRCs). In most eukaryotes, a GCP4/5/4/6 “core” complex promotes γ-tubulin small complex (γ-TuSC) association to generate cytosolic γ-TuRCs. Unlike γ-TuSCs, however, this core complex is non-essential in various species and absent from budding yeasts. In Drosophila, Spindle defective-2 (Spd-2) and Centrosomin (Cnn) redundantly recruit γ-tubulin complexes to mitotic centrosomes. Here we show that Spd-2 recruits γ-TuRCs formed via the GCP4/5/4/6 core, but that Cnn can recruit γ-TuSCs directly via its well-conserved CM1 domain, similar to its homologues in budding yeast. When centrosomes fail to recruit γ-tubulin complexes, they still nucleate microtubules via the TOG domain protein Mini-spindles (Msps), but these microtubules have different dynamic properties. Our data therefore help explain the dispensability of the GCP4/5/4/6 core and highlight the robustness of centrosomes as microtubule organising centres. They also suggest that the dynamic properties of microtubules are influenced by how they were nucleated.","PeriodicalId":343306,"journal":{"name":"The Journal of Cell Biology","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132144107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-20DOI: 10.1101/2023.02.20.529299
Pilar Rivero-Ríos, Takao Tsukahara, Tunahan Uygun, A. Chen, Garrett D. Chavis, S. Giridharan, Shigeki Iwase, M. A. Sutton, L. Weisman
Trafficking of cell-surface proteins from endosomes to the plasma membrane is a key mechanism to regulate synaptic function. In non-neuronal cells, proteins recycle to the plasma membrane either via the SNX27-Retromer-WASH pathway, or via the recently discovered SNX17-Retriever-CCC-WASH pathway. While SNX27 is responsible for the recycling of key neuronal receptors, the roles of SNX17 in neurons are less understood. Here, using cultured hippocampal neurons, we demonstrate that the SNX17 pathway regulates synaptic function and plasticity. Disruption of this pathway results in a loss of excitatory synapses and prevents structural plasticity during chemical long-term potentiation (cLTP). cLTP drives SNX17 recruitment to synapses, where its roles are in part mediated by regulating surface expression of β1-integrin. SNX17 recruitment relies on NMDAR activation, CamKII signaling, and requires binding to the Retriever and PI(3)P. Together, these findings provide molecular insights into the regulation of SNX17 at synapses, and define key roles for SNX17 in synaptic maintenance and in regulating enduring forms of synaptic plasticity.
细胞表面蛋白从核内体转运到质膜是调节突触功能的关键机制。在非神经元细胞中，蛋白质通过SNX27-Retromer-WASH途径或最近发现的snx17 - retriver - cc - wash途径再循环到质膜。虽然SNX27负责关键神经元受体的循环，但SNX17在神经元中的作用尚不清楚。通过培养海马神经元，我们证明SNX17通路调节突触功能和可塑性。这种通路的破坏导致兴奋性突触的丧失，并阻止化学长期增强(cLTP)过程中的结构可塑性。cLTP驱动SNX17募集到突触，其作用部分是通过调节β1-整合素的表面表达介导的。SNX17的招募依赖于NMDAR激活、CamKII信号，并且需要与寻回犬和PI(3)P结合。总之，这些发现为SNX17在突触中的调控提供了分子见解，并确定了SNX17在突触维持和调节持久形式的突触可塑性中的关键作用。
{"title":"Recruitment of the SNX17-Retriever recycling pathway regulates synaptic function and plasticity","authors":"Pilar Rivero-Ríos, Takao Tsukahara, Tunahan Uygun, A. Chen, Garrett D. Chavis, S. Giridharan, Shigeki Iwase, M. A. Sutton, L. Weisman","doi":"10.1101/2023.02.20.529299","DOIUrl":"https://doi.org/10.1101/2023.02.20.529299","url":null,"abstract":"Trafficking of cell-surface proteins from endosomes to the plasma membrane is a key mechanism to regulate synaptic function. In non-neuronal cells, proteins recycle to the plasma membrane either via the SNX27-Retromer-WASH pathway, or via the recently discovered SNX17-Retriever-CCC-WASH pathway. While SNX27 is responsible for the recycling of key neuronal receptors, the roles of SNX17 in neurons are less understood. Here, using cultured hippocampal neurons, we demonstrate that the SNX17 pathway regulates synaptic function and plasticity. Disruption of this pathway results in a loss of excitatory synapses and prevents structural plasticity during chemical long-term potentiation (cLTP). cLTP drives SNX17 recruitment to synapses, where its roles are in part mediated by regulating surface expression of β1-integrin. SNX17 recruitment relies on NMDAR activation, CamKII signaling, and requires binding to the Retriever and PI(3)P. Together, these findings provide molecular insights into the regulation of SNX17 at synapses, and define key roles for SNX17 in synaptic maintenance and in regulating enduring forms of synaptic plasticity.","PeriodicalId":343306,"journal":{"name":"The Journal of Cell Biology","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122351718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-18DOI: 10.1101/2022.05.23.492953
Tomoaki Sobajima, Katarzyna M. Kowalczyk, Stefanos Skylakakis, D. Hayward, Luke J. Fulcher, Colette Neary, Caleb Batley, Samvid Kurlekar, E. Roberts, U. Gruneberg, F. Barr
Amplification of the mitotic kinase Aurora A or loss of its regulator protein phosphatase 6 (PP6) have emerged as drivers of genome instability. Cells lacking PPP6C, the catalytic subunit of PP6, have amplified Aurora A activity and as we show here, enlarged mitotic spindles which fail to hold chromosomes tightly together in anaphase, causing defective nuclear structure. Using functional genomics to shed light on the processes underpinning these changes, we discover synthetic lethality between PPP6C and the kinetochore protein NDC80. We find that NDC80 is phosphorylated on multiple N-terminal sites during spindle formation by Aurora A-TPX2, exclusively at checkpoint-silenced, microtubule-attached kinetochores. NDC80 phosphorylation persists until spindle disassembly in telophase, is increased in PPP6C-knockout cells and, and is Aurora B-independent. An Aurora-phosphorylation-deficient NDC80-9A mutant reduces spindle size and suppresses defective nuclear structure in PPP6C-knockout cells. By regulating NDC80 phosphorylation by Aurora A-TPX2, PP6 plays an important role in mitotic spindle formation and size control, and thus the fidelity of cell division.
{"title":"PP6 regulation of Aurora A–TPX2 limits NDC80 phosphorylation and mitotic spindle size","authors":"Tomoaki Sobajima, Katarzyna M. Kowalczyk, Stefanos Skylakakis, D. Hayward, Luke J. Fulcher, Colette Neary, Caleb Batley, Samvid Kurlekar, E. Roberts, U. Gruneberg, F. Barr","doi":"10.1101/2022.05.23.492953","DOIUrl":"https://doi.org/10.1101/2022.05.23.492953","url":null,"abstract":"Amplification of the mitotic kinase Aurora A or loss of its regulator protein phosphatase 6 (PP6) have emerged as drivers of genome instability. Cells lacking PPP6C, the catalytic subunit of PP6, have amplified Aurora A activity and as we show here, enlarged mitotic spindles which fail to hold chromosomes tightly together in anaphase, causing defective nuclear structure. Using functional genomics to shed light on the processes underpinning these changes, we discover synthetic lethality between PPP6C and the kinetochore protein NDC80. We find that NDC80 is phosphorylated on multiple N-terminal sites during spindle formation by Aurora A-TPX2, exclusively at checkpoint-silenced, microtubule-attached kinetochores. NDC80 phosphorylation persists until spindle disassembly in telophase, is increased in PPP6C-knockout cells and, and is Aurora B-independent. An Aurora-phosphorylation-deficient NDC80-9A mutant reduces spindle size and suppresses defective nuclear structure in PPP6C-knockout cells. By regulating NDC80 phosphorylation by Aurora A-TPX2, PP6 plays an important role in mitotic spindle formation and size control, and thus the fidelity of cell division.","PeriodicalId":343306,"journal":{"name":"The Journal of Cell Biology","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115110561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-09DOI: 10.1101/2022.07.08.499406
M. L. Sosa Ponce, Mayrene Horta Remedios, Sarah Moradi-Fard, J. Cobb, V. Zaremberg
The nuclear envelope (NE) is important in maintaining genome organization. The role of lipids in the communication between the NE and telomere silencing was investigated, including how changes in lipid composition impact gene expression and overall nuclear architecture. For this purpose, yeast cells were treated with the non-metabolizable lysophosphatidylcholine analog edelfosine, known to accumulate at the perinuclear endoplasmic reticulum. Edelfosine treatment induced NE deformation and disrupted telomere clustering but not anchoring. In addition, the association of Sir4 at telomeres measured by ChIP decreased. RNA-seq analysis showed altered expression of Sir-dependent genes located at sub-telomeric (0-10 kb) regions, which was consistent with Sir4 dispersion. Transcriptomic analysis revealed that two lipid metabolic circuits were activated in response to edelfosine, one mediated by the membrane sensing transcription factors, Spt23/Mga2, and the other by a transcriptional repressor, Opi1. Activation of these combined transcriptional programs resulted in higher levels of unsaturated fatty acids and the formation of nuclear lipid droplets. Interestingly, cells lacking Sir proteins displayed resistance to unsaturated fatty acids and edelfosine, and this phenotype was connected to Rap1. GRAPHICAL ABSTRACT Summary The nuclear envelope (NE) is important for nuclear organization. This study shows that changes in NE lipid composition from lysolipid treatment decreases Sir4 association with telomeres, their clustering at NE, and triggers lipid-specific transcriptional circuits regulated by membrane-sensing factors.
{"title":"SIR telomere silencing depends on nuclear envelope lipids and modulates sensitivity to a lysolipid","authors":"M. L. Sosa Ponce, Mayrene Horta Remedios, Sarah Moradi-Fard, J. Cobb, V. Zaremberg","doi":"10.1101/2022.07.08.499406","DOIUrl":"https://doi.org/10.1101/2022.07.08.499406","url":null,"abstract":"The nuclear envelope (NE) is important in maintaining genome organization. The role of lipids in the communication between the NE and telomere silencing was investigated, including how changes in lipid composition impact gene expression and overall nuclear architecture. For this purpose, yeast cells were treated with the non-metabolizable lysophosphatidylcholine analog edelfosine, known to accumulate at the perinuclear endoplasmic reticulum. Edelfosine treatment induced NE deformation and disrupted telomere clustering but not anchoring. In addition, the association of Sir4 at telomeres measured by ChIP decreased. RNA-seq analysis showed altered expression of Sir-dependent genes located at sub-telomeric (0-10 kb) regions, which was consistent with Sir4 dispersion. Transcriptomic analysis revealed that two lipid metabolic circuits were activated in response to edelfosine, one mediated by the membrane sensing transcription factors, Spt23/Mga2, and the other by a transcriptional repressor, Opi1. Activation of these combined transcriptional programs resulted in higher levels of unsaturated fatty acids and the formation of nuclear lipid droplets. Interestingly, cells lacking Sir proteins displayed resistance to unsaturated fatty acids and edelfosine, and this phenotype was connected to Rap1. GRAPHICAL ABSTRACT Summary The nuclear envelope (NE) is important for nuclear organization. This study shows that changes in NE lipid composition from lysolipid treatment decreases Sir4 association with telomeres, their clustering at NE, and triggers lipid-specific transcriptional circuits regulated by membrane-sensing factors.","PeriodicalId":343306,"journal":{"name":"The Journal of Cell Biology","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123525648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-15DOI: 10.1101/2022.04.13.488131
Kirsten E. L. Garner, A. Salter, C. K. Lau, M. Gurusaran, Cécile Villemant, Elizabeth P. Granger, G. McNee, P. Woodman, O. Davies, B. Burke, V. Allan
Cytoplasmic dynein-driven movement of chromosomes during prophase I of mammalian meiosis is essential for synapsis and genetic exchange. Dynein connects to chromosome telomeres via KASH5 and SUN1 or SUN2, which together span the nuclear envelope. Here, we show that KASH5 promotes dynein motility in vitro, and cytosolic KASH5 inhibits dynein’s interphase functions. KASH5 interacts with either dynein light intermediate chain (DYNC1LI1 or DYNC1LI2) via a conserved helix in the LIC C-terminal, and this region is also needed for dynein’s recruitment to other cellular membranes. KASH5’s N-terminal EF-hands are essential, as the interaction with dynein is disrupted by mutation of key calcium-binding residues, although it is not regulated by cellular calcium levels. Dynein can be recruited to KASH5 at the nuclear envelope independently of dynactin, while LIS1 is essential for dynactin incorporation into the KASH5-dynein complex. Altogether, we show that the trans-membrane protein KASH5 is an activating adaptor for dynein, and shed light on the hierarchy of assembly of KASH5-dynein-dynactin complexes.
{"title":"The meiotic LINC complex component KASH5 is an activating adaptor for cytoplasmic dynein","authors":"Kirsten E. L. Garner, A. Salter, C. K. Lau, M. Gurusaran, Cécile Villemant, Elizabeth P. Granger, G. McNee, P. Woodman, O. Davies, B. Burke, V. Allan","doi":"10.1101/2022.04.13.488131","DOIUrl":"https://doi.org/10.1101/2022.04.13.488131","url":null,"abstract":"Cytoplasmic dynein-driven movement of chromosomes during prophase I of mammalian meiosis is essential for synapsis and genetic exchange. Dynein connects to chromosome telomeres via KASH5 and SUN1 or SUN2, which together span the nuclear envelope. Here, we show that KASH5 promotes dynein motility in vitro, and cytosolic KASH5 inhibits dynein’s interphase functions. KASH5 interacts with either dynein light intermediate chain (DYNC1LI1 or DYNC1LI2) via a conserved helix in the LIC C-terminal, and this region is also needed for dynein’s recruitment to other cellular membranes. KASH5’s N-terminal EF-hands are essential, as the interaction with dynein is disrupted by mutation of key calcium-binding residues, although it is not regulated by cellular calcium levels. Dynein can be recruited to KASH5 at the nuclear envelope independently of dynactin, while LIS1 is essential for dynactin incorporation into the KASH5-dynein complex. Altogether, we show that the trans-membrane protein KASH5 is an activating adaptor for dynein, and shed light on the hierarchy of assembly of KASH5-dynein-dynactin complexes.","PeriodicalId":343306,"journal":{"name":"The Journal of Cell Biology","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128699022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-24DOI: 10.1101/2022.11.24.517842
Isha Ralhan, Jinlan Chang, M. Moulton, Lindsey D. Goodman, Nathanael Lee, Gregory Plummer, H. Pasolli, D. Matthies, H. Bellen, Maria S. Ioannou
During oxidative stress neurons release lipids that are internalized by glia. Defects in this coordinated process play an important role in several neurodegenerative diseases. Yet, the mechanisms of lipid release and its consequences on neuronal health are unclear. Here, we demonstrate that lipid-protein particle release by autolysosome exocytosis protects neurons from ferroptosis, a form of cell death driven by lipid peroxidation. We show that during oxidative stress, peroxidated lipids and iron are released from neurons by autolysosomal exocytosis which requires the exocytic machinery; VAMP7 and syntaxin 4. We observe membrane-bound lipid-protein particles by TEM and demonstrate that these particles are released from neurons using cryoEM. Failure to release these lipid-protein particles causes lipid hydroperoxide and iron accumulation and sensitizes neurons to ferroptosis. Our results reveal how neurons protect themselves from peroxidated lipids. Given the number of brain pathologies that involve ferroptosis, defects in this pathway likely play a key role in the pathophysiology of neurodegenerative disease. SUMMARY Release of lipid-protein particles by autolysosomal exocytosis protects neurons from ferroptosis.
{"title":"Autolysosomal exocytosis of lipids protect neurons from ferroptosis","authors":"Isha Ralhan, Jinlan Chang, M. Moulton, Lindsey D. Goodman, Nathanael Lee, Gregory Plummer, H. Pasolli, D. Matthies, H. Bellen, Maria S. Ioannou","doi":"10.1101/2022.11.24.517842","DOIUrl":"https://doi.org/10.1101/2022.11.24.517842","url":null,"abstract":"During oxidative stress neurons release lipids that are internalized by glia. Defects in this coordinated process play an important role in several neurodegenerative diseases. Yet, the mechanisms of lipid release and its consequences on neuronal health are unclear. Here, we demonstrate that lipid-protein particle release by autolysosome exocytosis protects neurons from ferroptosis, a form of cell death driven by lipid peroxidation. We show that during oxidative stress, peroxidated lipids and iron are released from neurons by autolysosomal exocytosis which requires the exocytic machinery; VAMP7 and syntaxin 4. We observe membrane-bound lipid-protein particles by TEM and demonstrate that these particles are released from neurons using cryoEM. Failure to release these lipid-protein particles causes lipid hydroperoxide and iron accumulation and sensitizes neurons to ferroptosis. Our results reveal how neurons protect themselves from peroxidated lipids. Given the number of brain pathologies that involve ferroptosis, defects in this pathway likely play a key role in the pathophysiology of neurodegenerative disease. SUMMARY Release of lipid-protein particles by autolysosomal exocytosis protects neurons from ferroptosis.","PeriodicalId":343306,"journal":{"name":"The Journal of Cell Biology","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116594323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-10DOI: 10.1101/2022.11.10.516013
Rahel Dabrowski, Susanna Tulli, M. Graef
During autophagy, rapid membrane assembly expands small phagophores into large double-membrane autophagosomes. Theoretical modelling predicts the majority of autophagosomal phospholipids is derived from highly efficient non-vesicular phospholipid transfer (PLT) across phagophore-ER contacts (PERCS). Currently, the phagophore-ER tether Atg2 is the only PLT protein known to drive phagophore expansion in vivo. Here, our quantitative live-cell-imaging analysis reveals poor correlation between duration and size of forming autophagosomes and number of Atg2 molecules at PERCS of starving yeast cells. Strikingly, we find Atg2-mediated PLT is non-rate-limiting for autophagosome biogenesis, because membrane tether and PLT protein Vps13 localizes to the rim and promotes expansion of phagophores in parallel with Atg2. In the absence of Vps13, the number of Atg2 molecules at PERCS determines duration and size of forming autophagosomes with an apparent in vivo transfer rate of ~200 phospholipids per Atg2 molecule and second. We propose conserved PLT proteins cooperate in channeling phospholipids across organelle contact sites for non-rate-limiting membrane assembly during autophagosome biogenesis.
{"title":"Parallel phospholipid transfer by Vps13 and Atg2 determines autophagosome biogenesis dynamics","authors":"Rahel Dabrowski, Susanna Tulli, M. Graef","doi":"10.1101/2022.11.10.516013","DOIUrl":"https://doi.org/10.1101/2022.11.10.516013","url":null,"abstract":"During autophagy, rapid membrane assembly expands small phagophores into large double-membrane autophagosomes. Theoretical modelling predicts the majority of autophagosomal phospholipids is derived from highly efficient non-vesicular phospholipid transfer (PLT) across phagophore-ER contacts (PERCS). Currently, the phagophore-ER tether Atg2 is the only PLT protein known to drive phagophore expansion in vivo. Here, our quantitative live-cell-imaging analysis reveals poor correlation between duration and size of forming autophagosomes and number of Atg2 molecules at PERCS of starving yeast cells. Strikingly, we find Atg2-mediated PLT is non-rate-limiting for autophagosome biogenesis, because membrane tether and PLT protein Vps13 localizes to the rim and promotes expansion of phagophores in parallel with Atg2. In the absence of Vps13, the number of Atg2 molecules at PERCS determines duration and size of forming autophagosomes with an apparent in vivo transfer rate of ~200 phospholipids per Atg2 molecule and second. We propose conserved PLT proteins cooperate in channeling phospholipids across organelle contact sites for non-rate-limiting membrane assembly during autophagosome biogenesis.","PeriodicalId":343306,"journal":{"name":"The Journal of Cell Biology","volume":"222 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129295225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-06DOI: 10.1101/2022.06.22.497207
Gabriel Kreider-Letterman, Abel Castillo, Eike K. Mahlandt, J. Goedhart, Agustín Rabino, S. Goicoechea, R. García-Mata
Invadopodia formation is regulated by Rho GTPases. However, the molecular mechanisms that control Rho GTPase signaling at invadopodia remain poorly understood. Here, we have identified ARHGAP17, a Cdc42-specific RhoGAP, as a key regulator of invadopodia in breast cancer cells and by RhoGAPs characterized a novel ARHGAP17-mediated signaling pathway that controls the spatiotemporal activity of Cdc42 during invadopodia turnover. Our results show that during invadopodia assembly, ARHGAP17 localizes to the invadopodia ring and restricts the activity of Cdc42 to the invadopodia core, where it promotes invadopodia growth. Invadopodia disassembly starts when ARHGAP17 translocates from the invadopodia ring to the core, in a process that is mediated by its interaction with the Cdc42 effector CIP4. Once at the core, ARHGAP17 inactivates Cdc42 to promote invadopodia disassembly. Our results in invadopodia provide new insights on the coordinated transition between the activation and inactivation of Rho GTPases.
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