Pub Date : 2024-10-01Epub Date: 2024-08-21DOI: 10.1038/s44319-024-00225-3
Hong Nhung Vu, Matti Már Valdimarsson, Sara Sigurbjörnsdóttir, Kristín Bergsteinsdóttir, Julien Debbache, Keren Bismuth, Deborah A Swing, Jón H Hallsson, Lionel Larue, Heinz Arnheiter, Neal G Copeland, Nancy A Jenkins, Petur O Heidarsson, Eiríkur Steingrímsson
MITF, a basic Helix-Loop-Helix Zipper (bHLHZip) transcription factor, plays vital roles in melanocyte development and functions as an oncogene. We perform a genetic screen for suppressors of the Mitf-associated pigmentation phenotype in mice and identify an intragenic Mitf mutation that terminates MITF at the K316 SUMOylation site, leading to loss of the C-end intrinsically disordered region (IDR). The resulting protein is more nuclear but less stable than wild-type MITF and retains DNA-binding ability. As a dimer, it can translocate wild-type and mutant MITF partners into the nucleus, improving its own stability thus ensuring nuclear MITF supply. smFRET analysis shows interactions between K316 SUMOylation and S409 phosphorylation sites across monomers; these interactions largely explain the observed effects. The recurrent melanoma-associated E318K mutation in MITF, which affects K316 SUMOylation, also alters protein regulation in concert with S409. This suggests that residues K316 and S409 of MITF are impacted by SUMOylation and phosphorylation, respectively, mediating effects on nuclear localization and stability through conformational changes. Our work provides a novel mechanism of genetic suppression, and an example of how apparently deleterious mutations lead to normal phenotypes.
{"title":"Novel mechanisms of MITF regulation identified in a mouse suppressor screen.","authors":"Hong Nhung Vu, Matti Már Valdimarsson, Sara Sigurbjörnsdóttir, Kristín Bergsteinsdóttir, Julien Debbache, Keren Bismuth, Deborah A Swing, Jón H Hallsson, Lionel Larue, Heinz Arnheiter, Neal G Copeland, Nancy A Jenkins, Petur O Heidarsson, Eiríkur Steingrímsson","doi":"10.1038/s44319-024-00225-3","DOIUrl":"10.1038/s44319-024-00225-3","url":null,"abstract":"<p><p>MITF, a basic Helix-Loop-Helix Zipper (bHLHZip) transcription factor, plays vital roles in melanocyte development and functions as an oncogene. We perform a genetic screen for suppressors of the Mitf-associated pigmentation phenotype in mice and identify an intragenic Mitf mutation that terminates MITF at the K316 SUMOylation site, leading to loss of the C-end intrinsically disordered region (IDR). The resulting protein is more nuclear but less stable than wild-type MITF and retains DNA-binding ability. As a dimer, it can translocate wild-type and mutant MITF partners into the nucleus, improving its own stability thus ensuring nuclear MITF supply. smFRET analysis shows interactions between K316 SUMOylation and S409 phosphorylation sites across monomers; these interactions largely explain the observed effects. The recurrent melanoma-associated E318K mutation in MITF, which affects K316 SUMOylation, also alters protein regulation in concert with S409. This suggests that residues K316 and S409 of MITF are impacted by SUMOylation and phosphorylation, respectively, mediating effects on nuclear localization and stability through conformational changes. Our work provides a novel mechanism of genetic suppression, and an example of how apparently deleterious mutations lead to normal phenotypes.</p>","PeriodicalId":11541,"journal":{"name":"EMBO Reports","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11467436/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142016722","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 : 2024-10-01Epub Date: 2024-09-06DOI: 10.1038/s44319-024-00240-4
Sruthi Sunil, Simon Beeh, Eva Stöbbe, Kathrin Fischer, Franziska Wilhelm, Aron Meral, Celia Paris, Luisa Teasdale, Zhihao Jiang, Lisha Zhang, Moritz Urban, Emmanuel Aguilar Parras, Thorsten Nürnberger, Detlef Weigel, Rosa Lozano-Duran, Farid El Kasmi
Plants evolve nucleotide-binding leucine-rich repeat receptors (NLRs) to induce immunity. Activated coiled-coil (CC) domain containing NLRs (CNLs) oligomerize and form apparent cation channels promoting calcium influx and cell death, with the alpha-1 helix of the individual CC domains penetrating the plasma membranes. Some CNLs are characterized by putative N-myristoylation and S-acylation sites in their CC domain, potentially mediating permanent membrane association. Whether activated Potentially Membrane Localized NLRs (PMLs) mediate cell death and calcium influx in a similar way is unknown. We uncovered the cell-death function at the vacuole of an atypical but conserved Arabidopsis PML, PML5, which has a significant deletion in its CCG10/GA domain. Active PML5 oligomers localize in Golgi membranes and the tonoplast, alter vacuolar morphology, and induce cell death, with the short N-terminus being sufficient. Mutant analysis supports a potential role of PMLs in plant immunity. PML5-like deletions are found in several Brassicales paralogs, pointing to the evolutionary importance of this innovation. PML5, with its minimal CC domain, represents the first identified CNL utilizing vacuolar-stored calcium for cell death induction.
植物进化出核苷酸结合富亮氨酸重复受体(NLRs)来诱导免疫。活化的含盘绕线圈(CC)结构域的 NLRs(CNLs)会寡聚并形成明显的阳离子通道,促进钙离子流入和细胞死亡,单个 CC 结构域的 alpha-1 螺旋可穿透质膜。一些 CNL 的特征是其 CC 结构域中存在假定的 N-肉豆蔻酰化和 S-酰化位点,从而有可能介导永久性膜关联。活化的潜在膜定位 NLRs(PMLs)是否以类似方式介导细胞死亡和钙离子流入尚不清楚。我们发现了拟南芥一种非典型但保守的 PML(PML5)在液泡中的细胞死亡功能,该 PML5 的 CCG10/GA 结构域有显著缺失。活性 PML5 寡聚体定位在高尔基体膜和调质体中,改变液泡形态并诱导细胞死亡,短 N 端足以诱导细胞死亡。突变体分析支持 PML 在植物免疫中的潜在作用。在几种十字花科植物的旁系亲缘植物中发现了类似于 PML5 的缺失,这表明了这一创新在进化过程中的重要性。PML5 具有最小的 CC 结构域,是第一个利用液泡储存的钙诱导细胞死亡的 CNL。
{"title":"Activation of an atypical plant NLR with an N-terminal deletion initiates cell death at the vacuole.","authors":"Sruthi Sunil, Simon Beeh, Eva Stöbbe, Kathrin Fischer, Franziska Wilhelm, Aron Meral, Celia Paris, Luisa Teasdale, Zhihao Jiang, Lisha Zhang, Moritz Urban, Emmanuel Aguilar Parras, Thorsten Nürnberger, Detlef Weigel, Rosa Lozano-Duran, Farid El Kasmi","doi":"10.1038/s44319-024-00240-4","DOIUrl":"10.1038/s44319-024-00240-4","url":null,"abstract":"<p><p>Plants evolve nucleotide-binding leucine-rich repeat receptors (NLRs) to induce immunity. Activated coiled-coil (CC) domain containing NLRs (CNLs) oligomerize and form apparent cation channels promoting calcium influx and cell death, with the alpha-1 helix of the individual CC domains penetrating the plasma membranes. Some CNLs are characterized by putative N-myristoylation and S-acylation sites in their CC domain, potentially mediating permanent membrane association. Whether activated Potentially Membrane Localized NLRs (PMLs) mediate cell death and calcium influx in a similar way is unknown. We uncovered the cell-death function at the vacuole of an atypical but conserved Arabidopsis PML, PML5, which has a significant deletion in its CC<sub>G10/GA</sub> domain. Active PML5 oligomers localize in Golgi membranes and the tonoplast, alter vacuolar morphology, and induce cell death, with the short N-terminus being sufficient. Mutant analysis supports a potential role of PMLs in plant immunity. PML5-like deletions are found in several Brassicales paralogs, pointing to the evolutionary importance of this innovation. PML5, with its minimal CC domain, represents the first identified CNL utilizing vacuolar-stored calcium for cell death induction.</p>","PeriodicalId":11541,"journal":{"name":"EMBO Reports","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11467418/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142145317","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 : 2024-10-01Epub Date: 2024-09-06DOI: 10.1038/s44319-024-00239-x
Kiae Kim, Ka Young Chung
Phosphorylated residues of G protein-coupled receptors bind to the N-domain of arrestin, resulting in the release of its C-terminus. This induces further allosteric conformational changes, such as polar core disruption, alteration of interdomain loops, and domain rotation, which transform arrestins into the receptor-activated state. It is widely accepted that arrestin activation occurs by conformational changes propagated from the N- to the C-domain. However, recent studies have revealed that binding of phosphatidylinositol 4,5-bisphosphate (PIP2) to the C-domain transforms arrestins into a pre-active state. Here, we aimed to elucidate the mechanisms underlying PIP2-induced arrestin pre-activation. We compare the conformational changes of β-arrestin-2 upon binding of PIP2 or phosphorylated C-tail peptide of vasopressin receptor type 2 using hydrogen/deuterium exchange mass spectrometry (HDX-MS). Introducing point mutations on the potential routes of the allosteric conformational changes and analyzing these mutant constructs with HDX-MS reveals that PIP2-binding at the C-domain affects the back loop, which destabilizes the gate loop and βXX to transform β-arrestin-2 into the pre-active state.
G 蛋白偶联受体的磷酸化残基与 arrestin 的 N 域结合,导致其 C 端释放。这会诱发进一步的异构构象变化,如极性核破坏、域间环改变和域旋转,从而将捕捉素转变为受体激活状态。人们普遍认为,捕获素的激活是通过从 N 域到 C 域的构象变化实现的。然而,最近的研究发现,磷脂酰肌醇 4,5-二磷酸(PIP2)与 C-结构域的结合会使捕捉素转变为前激活状态。在这里,我们旨在阐明 PIP2 诱导的 arrestins 预激活的机制。我们利用氢/氘交换质谱法(HDX-MS)比较了β-arrestin-2与PIP2或加压素受体2型磷酸化C尾肽结合时的构象变化。在异构构象变化的潜在途径上引入点突变,并用 HDX-MS 分析这些突变体构建物,发现 PIP2 结合 C 域会影响后环,从而破坏门环和 βXX 的稳定性,使 β-arrestin-2 转变为前活性状态。
{"title":"Molecular mechanism of β-arrestin-2 pre-activation by phosphatidylinositol 4,5-bisphosphate.","authors":"Kiae Kim, Ka Young Chung","doi":"10.1038/s44319-024-00239-x","DOIUrl":"10.1038/s44319-024-00239-x","url":null,"abstract":"<p><p>Phosphorylated residues of G protein-coupled receptors bind to the N-domain of arrestin, resulting in the release of its C-terminus. This induces further allosteric conformational changes, such as polar core disruption, alteration of interdomain loops, and domain rotation, which transform arrestins into the receptor-activated state. It is widely accepted that arrestin activation occurs by conformational changes propagated from the N- to the C-domain. However, recent studies have revealed that binding of phosphatidylinositol 4,5-bisphosphate (PIP<sub>2</sub>) to the C-domain transforms arrestins into a pre-active state. Here, we aimed to elucidate the mechanisms underlying PIP<sub>2</sub>-induced arrestin pre-activation. We compare the conformational changes of β-arrestin-2 upon binding of PIP<sub>2</sub> or phosphorylated C-tail peptide of vasopressin receptor type 2 using hydrogen/deuterium exchange mass spectrometry (HDX-MS). Introducing point mutations on the potential routes of the allosteric conformational changes and analyzing these mutant constructs with HDX-MS reveals that PIP<sub>2</sub>-binding at the C-domain affects the back loop, which destabilizes the gate loop and βXX to transform β-arrestin-2 into the pre-active state.</p>","PeriodicalId":11541,"journal":{"name":"EMBO Reports","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11467438/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142145319","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 : 2024-10-01Epub Date: 2024-09-13DOI: 10.1038/s44319-024-00251-1
Angus T Stock, Sarah Parsons, Jacinta A Hansen, Damian B D'Silva, Graham Starkey, Aly Fayed, Xin Yi Lim, Rohit D'Costa, Claire L Gordon, Ian P Wicks
The accumulation of myofibroblasts within the intimal layer of inflamed blood vessels is a potentially catastrophic complication of vasculitis, which can lead to arterial stenosis and ischaemia. In this study, we have investigated how these luminal myofibroblasts develop during Kawasaki disease (KD), a paediatric vasculitis typically involving the coronary arteries. By performing lineage tracing studies in a murine model of KD, we reveal that luminal myofibroblasts develop independently of adventitial fibroblasts and endothelial cells, and instead derive from smooth muscle cells (SMCs). Notably, the emergence of SMC-derived luminal myofibroblasts-in both mice and patients with KD, Takayasu's arteritis and Giant Cell arteritis-coincided with activation of the mechanistic target of rapamycin (mTOR) signalling pathway. Moreover, SMC-specific deletion of mTOR signalling, or pharmacological inhibition, abrogated the emergence of luminal myofibroblasts. Thus, mTOR is an intrinsic and essential regulator of luminal myofibroblast formation that is activated in vasculitis patients and therapeutically tractable. These findings provide molecular insight into the pathogenesis of coronary artery stenosis and identify mTOR as a therapeutic target in vasculitis.
{"title":"mTOR signalling controls the formation of smooth muscle cell-derived luminal myofibroblasts during vasculitis.","authors":"Angus T Stock, Sarah Parsons, Jacinta A Hansen, Damian B D'Silva, Graham Starkey, Aly Fayed, Xin Yi Lim, Rohit D'Costa, Claire L Gordon, Ian P Wicks","doi":"10.1038/s44319-024-00251-1","DOIUrl":"10.1038/s44319-024-00251-1","url":null,"abstract":"<p><p>The accumulation of myofibroblasts within the intimal layer of inflamed blood vessels is a potentially catastrophic complication of vasculitis, which can lead to arterial stenosis and ischaemia. In this study, we have investigated how these luminal myofibroblasts develop during Kawasaki disease (KD), a paediatric vasculitis typically involving the coronary arteries. By performing lineage tracing studies in a murine model of KD, we reveal that luminal myofibroblasts develop independently of adventitial fibroblasts and endothelial cells, and instead derive from smooth muscle cells (SMCs). Notably, the emergence of SMC-derived luminal myofibroblasts-in both mice and patients with KD, Takayasu's arteritis and Giant Cell arteritis-coincided with activation of the mechanistic target of rapamycin (mTOR) signalling pathway. Moreover, SMC-specific deletion of mTOR signalling, or pharmacological inhibition, abrogated the emergence of luminal myofibroblasts. Thus, mTOR is an intrinsic and essential regulator of luminal myofibroblast formation that is activated in vasculitis patients and therapeutically tractable. These findings provide molecular insight into the pathogenesis of coronary artery stenosis and identify mTOR as a therapeutic target in vasculitis.</p>","PeriodicalId":11541,"journal":{"name":"EMBO Reports","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11467406/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142282182","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 : 2024-10-01Epub Date: 2024-08-27DOI: 10.1038/s44319-024-00232-4
Zaineb Javed, Dong Hui Shin, Weihua Pan, Sierra R White, Amal Taher Elhaw, Yeon Soo Kim, Shriya Kamlapurkar, Ya-Yun Cheng, J Cory Benson, Ahmed Emam Abdelnaby, Rébécca Phaëton, Hong-Gang Wang, Shengyu Yang, Mara L G Sullivan, Claudette M St Croix, Simon C Watkins, Steven J Mullett, Stacy L Gelhaus, Nam Lee, Lan G Coffman, Katherine M Aird, Mohamed Trebak, Karthikeyan Mythreye, Vonn Walter, Nadine Hempel
Aberrant mitochondrial fission/fusion dynamics are frequently associated with pathologies, including cancer. We show that alternative splice variants of the fission protein Drp1 (DNM1L) contribute to the complexity of mitochondrial fission/fusion regulation in tumor cells. High tumor expression of the Drp1 alternative splice variant lacking exon 16 relative to other transcripts is associated with poor outcome in ovarian cancer patients. Lack of exon 16 results in Drp1 localization to microtubules and decreased association with mitochondrial fission sites, culminating in fused mitochondrial networks, enhanced respiration, changes in metabolism, and enhanced pro-tumorigenic phenotypes in vitro and in vivo. These effects are inhibited by siRNAs designed to specifically target the endogenously expressed transcript lacking exon 16. Moreover, lack of exon 16 abrogates mitochondrial fission in response to pro-apoptotic stimuli and leads to decreased sensitivity to chemotherapeutics. These data emphasize the pathophysiological importance of Drp1 alternative splicing, highlight the divergent functions and consequences of changing the relative expression of Drp1 splice variants in tumor cells, and strongly warrant consideration of alternative splicing in future studies focused on Drp1.
{"title":"Drp1 splice variants regulate ovarian cancer mitochondrial dynamics and tumor progression.","authors":"Zaineb Javed, Dong Hui Shin, Weihua Pan, Sierra R White, Amal Taher Elhaw, Yeon Soo Kim, Shriya Kamlapurkar, Ya-Yun Cheng, J Cory Benson, Ahmed Emam Abdelnaby, Rébécca Phaëton, Hong-Gang Wang, Shengyu Yang, Mara L G Sullivan, Claudette M St Croix, Simon C Watkins, Steven J Mullett, Stacy L Gelhaus, Nam Lee, Lan G Coffman, Katherine M Aird, Mohamed Trebak, Karthikeyan Mythreye, Vonn Walter, Nadine Hempel","doi":"10.1038/s44319-024-00232-4","DOIUrl":"10.1038/s44319-024-00232-4","url":null,"abstract":"<p><p>Aberrant mitochondrial fission/fusion dynamics are frequently associated with pathologies, including cancer. We show that alternative splice variants of the fission protein Drp1 (DNM1L) contribute to the complexity of mitochondrial fission/fusion regulation in tumor cells. High tumor expression of the Drp1 alternative splice variant lacking exon 16 relative to other transcripts is associated with poor outcome in ovarian cancer patients. Lack of exon 16 results in Drp1 localization to microtubules and decreased association with mitochondrial fission sites, culminating in fused mitochondrial networks, enhanced respiration, changes in metabolism, and enhanced pro-tumorigenic phenotypes in vitro and in vivo. These effects are inhibited by siRNAs designed to specifically target the endogenously expressed transcript lacking exon 16. Moreover, lack of exon 16 abrogates mitochondrial fission in response to pro-apoptotic stimuli and leads to decreased sensitivity to chemotherapeutics. These data emphasize the pathophysiological importance of Drp1 alternative splicing, highlight the divergent functions and consequences of changing the relative expression of Drp1 splice variants in tumor cells, and strongly warrant consideration of alternative splicing in future studies focused on Drp1.</p>","PeriodicalId":11541,"journal":{"name":"EMBO Reports","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11467262/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142079668","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}
Despite the efficacy of highly active antiretroviral therapy in controlling the incidence and mortality of AIDS, effective interventions for HIV-1-induced neurological damage and cognitive impairment remain elusive. In this study, we found that HIV-1 infection can induce proteolytic cleavage and aberrant aggregation of TAR DNA-binding protein 43 (TDP-43), a pathological protein associated with various severe neurological disorders. The HIV-1 accessory protein Vpu was found to be responsible for the cleavage of TDP-43, as ectopic expression of Vpu alone was sufficient to induce TDP-43 cleavage, whereas HIV-1 lacking Vpu failed to cleave TDP-43. Mechanistically, the cleavage of TDP-43 at Asp89 by HIV-1 relies on Vpu-mediated activation of Caspase 3, and pharmacological inhibition of Caspase 3 activity effectively suppressed the HIV-1-induced aggregation and neurotoxicity of TDP-43. Overall, these results suggest that TDP-43 is a conserved host target of HIV-1 Vpu and provide evidence for the involvement of TDP-43 dysregulation in the neural pathogenesis of HIV-1.
尽管高效抗逆转录病毒疗法能有效控制艾滋病的发病率和死亡率,但针对 HIV-1 引起的神经系统损伤和认知障碍的有效干预措施却仍遥遥无期。在这项研究中,我们发现 HIV-1 感染可诱导 TAR DNA 结合蛋白 43(TDP-43)的蛋白水解和异常聚集,而 TAR DNA 结合蛋白 43 是一种与各种严重神经系统疾病相关的病理蛋白。研究发现,HIV-1辅助蛋白Vpu是TDP-43裂解的元凶,因为仅异位表达Vpu就足以诱导TDP-43裂解,而缺乏Vpu的HIV-1则无法裂解TDP-43。从机理上讲,HIV-1 在 Asp89 处裂解 TDP-43 依赖于 Vpu 介导的 Caspase 3 激活,而药物抑制 Caspase 3 的活性可有效抑制 HIV-1 诱导的 TDP-43 聚集和神经毒性。总之,这些结果表明,TDP-43是HIV-1 Vpu的一个保守宿主靶标,并为TDP-43失调参与HIV-1的神经发病机制提供了证据。
{"title":"HIV-1 Vpu induces neurotoxicity by promoting Caspase 3-dependent cleavage of TDP-43.","authors":"Jiaxin Yang, Yan Li, Huili Li, Haichen Zhang, Haoran Guo, Xiangyu Zheng, Xiao-Fang Yu, Wei Wei","doi":"10.1038/s44319-024-00238-y","DOIUrl":"10.1038/s44319-024-00238-y","url":null,"abstract":"<p><p>Despite the efficacy of highly active antiretroviral therapy in controlling the incidence and mortality of AIDS, effective interventions for HIV-1-induced neurological damage and cognitive impairment remain elusive. In this study, we found that HIV-1 infection can induce proteolytic cleavage and aberrant aggregation of TAR DNA-binding protein 43 (TDP-43), a pathological protein associated with various severe neurological disorders. The HIV-1 accessory protein Vpu was found to be responsible for the cleavage of TDP-43, as ectopic expression of Vpu alone was sufficient to induce TDP-43 cleavage, whereas HIV-1 lacking Vpu failed to cleave TDP-43. Mechanistically, the cleavage of TDP-43 at Asp89 by HIV-1 relies on Vpu-mediated activation of Caspase 3, and pharmacological inhibition of Caspase 3 activity effectively suppressed the HIV-1-induced aggregation and neurotoxicity of TDP-43. Overall, these results suggest that TDP-43 is a conserved host target of HIV-1 Vpu and provide evidence for the involvement of TDP-43 dysregulation in the neural pathogenesis of HIV-1.</p>","PeriodicalId":11541,"journal":{"name":"EMBO Reports","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11467202/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142145318","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 : 2024-10-01Epub Date: 2024-09-06DOI: 10.1038/s44319-024-00235-1
Kang Zhu, Chatrin Chatrin, Marcin J Suskiewicz, Vincent Aucagne, Benjamin Foster, Benedikt M Kessler, Ian Gibbs-Seymour, Dragana Ahel, Ivan Ahel
The recent discovery of non-proteinaceous ubiquitylation substrates broadened our understanding of this modification beyond conventional protein targets. However, the existence of additional types of substrates remains elusive. Here, we present evidence that nucleic acids can also be directly ubiquitylated via ester bond formation. DTX3L, a member of the DELTEX family E3 ubiquitin ligases, ubiquitylates DNA and RNA in vitro and that this activity is shared with DTX3, but not with the other DELTEX family members DTX1, DTX2 and DTX4. DTX3L shows preference for the 3'-terminal adenosine over other nucleotides. In addition, we demonstrate that ubiquitylation of nucleic acids is reversible by DUBs such as USP2, JOSD1 and SARS-CoV-2 PLpro. Overall, our study proposes reversible ubiquitylation of nucleic acids in vitro and discusses its potential functional implications.
{"title":"Ubiquitylation of nucleic acids by DELTEX ubiquitin E3 ligase DTX3L.","authors":"Kang Zhu, Chatrin Chatrin, Marcin J Suskiewicz, Vincent Aucagne, Benjamin Foster, Benedikt M Kessler, Ian Gibbs-Seymour, Dragana Ahel, Ivan Ahel","doi":"10.1038/s44319-024-00235-1","DOIUrl":"10.1038/s44319-024-00235-1","url":null,"abstract":"<p><p>The recent discovery of non-proteinaceous ubiquitylation substrates broadened our understanding of this modification beyond conventional protein targets. However, the existence of additional types of substrates remains elusive. Here, we present evidence that nucleic acids can also be directly ubiquitylated via ester bond formation. DTX3L, a member of the DELTEX family E3 ubiquitin ligases, ubiquitylates DNA and RNA in vitro and that this activity is shared with DTX3, but not with the other DELTEX family members DTX1, DTX2 and DTX4. DTX3L shows preference for the 3'-terminal adenosine over other nucleotides. In addition, we demonstrate that ubiquitylation of nucleic acids is reversible by DUBs such as USP2, JOSD1 and SARS-CoV-2 PLpro. Overall, our study proposes reversible ubiquitylation of nucleic acids in vitro and discusses its potential functional implications.</p>","PeriodicalId":11541,"journal":{"name":"EMBO Reports","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11467253/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142145320","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 : 2024-09-27DOI: 10.1038/s44319-024-00266-8
Rajendra Kumar Angara, Arif Sadi, Stacey D Gilk
Effective intracellular communication between cellular organelles occurs at dedicated membrane contact sites (MCSs). Tether proteins are responsible for the establishment of MCSs, enabling direct communication between organelles to ensure organelle function and host cell homeostasis. While recent research has identified tether proteins in several bacterial pathogens, their functions have predominantly been associated with mediating inter-organelle communication between the bacteria containing vacuole (BCV) and the host endoplasmic reticulum (ER). Here, we identify a novel bacterial effector protein, CbEPF1, which acts as a molecular tether beyond the confines of the BCV and facilitates interactions between host cell organelles. Coxiella burnetii, an obligate intracellular bacterial pathogen, encodes the FFAT motif-containing protein CbEPF1 which localizes to host lipid droplets (LDs). CbEPF1 establishes inter-organelle contact sites between host LDs and the ER through its interactions with VAP family proteins. Intriguingly, CbEPF1 modulates growth of host LDs in a FFAT motif-dependent manner. These findings highlight the potential for bacterial effector proteins to impact host cellular homeostasis by manipulating inter-organelle communication beyond conventional BCVs.
{"title":"A novel bacterial effector protein mediates ER-LD membrane contacts to regulate host lipid droplets.","authors":"Rajendra Kumar Angara, Arif Sadi, Stacey D Gilk","doi":"10.1038/s44319-024-00266-8","DOIUrl":"10.1038/s44319-024-00266-8","url":null,"abstract":"<p><p>Effective intracellular communication between cellular organelles occurs at dedicated membrane contact sites (MCSs). Tether proteins are responsible for the establishment of MCSs, enabling direct communication between organelles to ensure organelle function and host cell homeostasis. While recent research has identified tether proteins in several bacterial pathogens, their functions have predominantly been associated with mediating inter-organelle communication between the bacteria containing vacuole (BCV) and the host endoplasmic reticulum (ER). Here, we identify a novel bacterial effector protein, CbEPF1, which acts as a molecular tether beyond the confines of the BCV and facilitates interactions between host cell organelles. Coxiella burnetii, an obligate intracellular bacterial pathogen, encodes the FFAT motif-containing protein CbEPF1 which localizes to host lipid droplets (LDs). CbEPF1 establishes inter-organelle contact sites between host LDs and the ER through its interactions with VAP family proteins. Intriguingly, CbEPF1 modulates growth of host LDs in a FFAT motif-dependent manner. These findings highlight the potential for bacterial effector proteins to impact host cellular homeostasis by manipulating inter-organelle communication beyond conventional BCVs.</p>","PeriodicalId":11541,"journal":{"name":"EMBO Reports","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142343796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1038/s44319-024-00253-z
Theresa M Welle,Dipen Rajgor,Dean J Kareemo,Joshua D Garcia,Sarah M Zych,Sarah E Wolfe,Sara E Gookin,Tyler P Martinez,Mark L Dell'Acqua,Christopher P Ford,Matthew J Kennedy,Katharine R Smith
Activity-dependent protein synthesis is crucial for long-lasting forms of synaptic plasticity. However, our understanding of translational mechanisms controlling GABAergic synapses is limited. One distinct form of inhibitory long-term potentiation (iLTP) enhances postsynaptic clusters of GABAARs and the primary inhibitory scaffold, gephyrin, to promote sustained synaptic strengthening. While we previously found that persistent iLTP requires mRNA translation, the mechanisms controlling plasticity-induced gephyrin translation remain unknown. We identify miR153 as a novel regulator of Gphn mRNA translation which controls gephyrin protein levels and synaptic clustering, ultimately impacting inhibitory synaptic structure and function. iLTP induction downregulates miR153, reversing its translational suppression of Gphn mRNA and promoting de novo gephyrin protein synthesis and synaptic clustering during iLTP. Finally, we find that reduced miR153 expression during iLTP is driven by an excitation-transcription coupling pathway involving calcineurin, NFAT and HDACs, which also controls the miRNA-dependent upregulation of GABAARs. Together, we delineate a miRNA-dependent post-transcriptional mechanism that controls the expression of the key synaptic scaffold, gephyrin, and may converge with parallel miRNA pathways to coordinate gene upregulation to maintain inhibitory synaptic plasticity.
{"title":"miRNA-mediated control of gephyrin synthesis drives sustained inhibitory synaptic plasticity.","authors":"Theresa M Welle,Dipen Rajgor,Dean J Kareemo,Joshua D Garcia,Sarah M Zych,Sarah E Wolfe,Sara E Gookin,Tyler P Martinez,Mark L Dell'Acqua,Christopher P Ford,Matthew J Kennedy,Katharine R Smith","doi":"10.1038/s44319-024-00253-z","DOIUrl":"https://doi.org/10.1038/s44319-024-00253-z","url":null,"abstract":"Activity-dependent protein synthesis is crucial for long-lasting forms of synaptic plasticity. However, our understanding of translational mechanisms controlling GABAergic synapses is limited. One distinct form of inhibitory long-term potentiation (iLTP) enhances postsynaptic clusters of GABAARs and the primary inhibitory scaffold, gephyrin, to promote sustained synaptic strengthening. While we previously found that persistent iLTP requires mRNA translation, the mechanisms controlling plasticity-induced gephyrin translation remain unknown. We identify miR153 as a novel regulator of Gphn mRNA translation which controls gephyrin protein levels and synaptic clustering, ultimately impacting inhibitory synaptic structure and function. iLTP induction downregulates miR153, reversing its translational suppression of Gphn mRNA and promoting de novo gephyrin protein synthesis and synaptic clustering during iLTP. Finally, we find that reduced miR153 expression during iLTP is driven by an excitation-transcription coupling pathway involving calcineurin, NFAT and HDACs, which also controls the miRNA-dependent upregulation of GABAARs. Together, we delineate a miRNA-dependent post-transcriptional mechanism that controls the expression of the key synaptic scaffold, gephyrin, and may converge with parallel miRNA pathways to coordinate gene upregulation to maintain inhibitory synaptic plasticity.","PeriodicalId":11541,"journal":{"name":"EMBO Reports","volume":null,"pages":null},"PeriodicalIF":7.7,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}