{"title":"Sodium arsenite induces aggresome formation by promoting PICK1 BAR domain homodimer formation.","authors":"John Ho Chun Lai, Marianthi Tsogka, Jun Xia","doi":"10.1091/mbc.E24-05-0201","DOIUrl":"10.1091/mbc.E24-05-0201","url":null,"abstract":"<p><p>The aggresome is a perinuclear structure that sequesters misfolded proteins. It is implicated in various neurodegenerative diseases. The perinuclear structure enriched with protein interacting with C kinase 1 (PICK1) was found to be inducible by cellular stressors, colocalizing with microtubule-organizing center markers and ubiquitin, hence classifying it as an aggresome. Sodium arsenite but not arsenate was found to potently induce aggresome formation through an integrated stress response-independent pathway. In HEK293T cells, under arsenite stress, PICK1 localization to the aggresome was prioritized, and formation of PICK1 homodimers was favored. Additionally, PICK1 could enhance protein entry into aggresomes. This study shows that arsenite can induce the formation of both RNA stress granules and aggresomes at the same time, and that PICK1 shows conditional localization to aggresomes, suggesting a possible involvement of PICK1 in neurodegenerative diseases.</p>","PeriodicalId":18735,"journal":{"name":"Molecular Biology of the Cell","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11481693/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141860286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ian Eder, Virginia Yu, Jacob Antonello, Fangyuan Chen, David Gau, Pooja Chawla, Marion Joy, Peter C Lucas, David Boone, Adrian V Lee, Partha Roy
{"title":"mDia2 is an important mediator of MRTF-A-dependent regulation of breast cancer cell migration.","authors":"Ian Eder, Virginia Yu, Jacob Antonello, Fangyuan Chen, David Gau, Pooja Chawla, Marion Joy, Peter C Lucas, David Boone, Adrian V Lee, Partha Roy","doi":"10.1091/mbc.E24-01-0008","DOIUrl":"10.1091/mbc.E24-01-0008","url":null,"abstract":"<p><p>Dysregulated actin cytoskeleton gives rise to aberrant cell motility and metastatic spread of tumor cells. This study evaluates the effect of overexpression of wild-type versus functional mutants of MRTF-A on migration and invasion of breast cancer (BC) cells. Our studies indicate that SRF's interaction is critical for MRTF-A-induced promotion of both two-dimensional and three-dimensional cell migration, while the SAP-domain function is important selectively for three-dimensional cell migration. Increased MRTF-A activity is associated with more effective membrane protrusion, a phenotype that is attributed predominantly to SRF's interaction with MRTF. We demonstrate formin-family protein mDia2 as an important mediator of MRTF-stimulated actin polymerization at the leading edge and cell migration. Multiplexed quantitative immunohistochemistry and transcriptome analyses of clinical BC specimens further demonstrate a positive correlation between nuclear localization of MRTF with malignant traits of cancer cells and enrichment of MRTF-SRF gene signature in pair-matched distant metastases versus primary tumors. In conclusion, this study establishes a novel mechanism of MRTF-dependent regulation of cell migration and provides evidence for the association between MRTF activity and increased malignancy in human BC, justifying future development of specific small molecule inhibitors of the MRTF-SRF transcriptional complex as potential therapeutic agents in BC.</p>","PeriodicalId":18735,"journal":{"name":"Molecular Biology of the Cell","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11481706/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142086179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Julian R Smith, Angela A Arellano, Daphne C Avgousti
{"title":"Viral imitation is the sincerest form of epigenetic flattery.","authors":"Julian R Smith, Angela A Arellano, Daphne C Avgousti","doi":"10.1091/mbc.E23-04-0147","DOIUrl":"10.1091/mbc.E23-04-0147","url":null,"abstract":"<p><p>Viruses use multiple strategies to successfully generate progeny and overcome host defenses. In recent years, it has become increasingly evident that epigenetic mechanisms of host gene regulation are vulnerable to viral manipulation. In the form of histone mimicry, viral invasion of host chromatin is a striking example of how viruses have evolved to invade every aspect of cellular function for viral benefit. In this perspective, we will review how three viruses-influenza A, SARS-CoV-2, and <i>Cotesia plutellae</i> bracovirus-use histone mimicry to promote viral success through immune evasion. These examples highlight the importance of this burgeoning field and point toward the wealth of knowledge we have yet to uncover.</p>","PeriodicalId":18735,"journal":{"name":"Molecular Biology of the Cell","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11481696/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142291467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
David J Doobin, Paige Helmer, Aurelie Carabalona, Chiara Bertipaglia, Richard B Vallee
{"title":"The Role of Nde1 phosphorylation in interkinetic nuclear migration and neural migration during cortical development.","authors":"David J Doobin, Paige Helmer, Aurelie Carabalona, Chiara Bertipaglia, Richard B Vallee","doi":"10.1091/mbc.E24-05-0217","DOIUrl":"10.1091/mbc.E24-05-0217","url":null,"abstract":"<p><p>Nde1 is a cytoplasmic dynein regulatory protein with important roles in vertebrate brain development. One noteworthy function is in the nuclear oscillatory behavior in neural progenitor cells, the control and mechanism of which remain poorly understood. Nde1 contains multiple phosphorylation sites for the cell cycle-dependent protein kinase CDK1, though the function of these sites is not well understood. To test their role in brain development, we expressed phosphorylation-state mutant forms of Nde1 in embryonic rat brains using in utero electroporation. We find that Nde1 T215 and T243 phosphomutants block apical interkinetic nuclear migration (INM) and, consequently, mitosis in radial glial progenitor cells. Another Nde1 phosphomutant at T246 also interfered with mitotic entry without affecting INM, suggesting a more direct role for Nde1 T246 in mitotic regulation. We also found that the Nde1 S214F mutation, which is associated with schizophrenia, inhibits Cdk5 phosphorylation at an adjacent residue which causes alterations in neuronal lamination. These results together identify important new roles for Nde1 phosphorylation in neocortical development and disease, and represent the first evidence for Nde1 phosphorylation roles in INM and neuronal lamination.</p>","PeriodicalId":18735,"journal":{"name":"Molecular Biology of the Cell","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11481692/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142017996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marco A Alfonzo-Méndez,Marie-Paule Strub,Justin W Taraska
{"title":"Spatial and signaling overlap of growth factor receptor systems at clathrin-coated sites.","authors":"Marco A Alfonzo-Méndez,Marie-Paule Strub,Justin W Taraska","doi":"10.1091/mbc.e24-05-0226","DOIUrl":"https://doi.org/10.1091/mbc.e24-05-0226","url":null,"abstract":"Cellular communication is regulated at the plasma membrane by the interactions of receptor, adhesion, signaling, and endocytic proteins. Yet, the composition and control of these complexes in response to external cues remain unclear. We use high-resolution and high-throughput fluorescence imaging to map the localization of growth factor receptors and related proteins at single clathrin-coated structures in human squamous HSC3 cells. We find distinct protein signatures between control cells and cells stimulated with growth factors. Clathrin sites at the plasma membrane are preloaded with some receptors but not others. Stimulation with epidermal growth factor induces capture and concentration of epidermal growth factor-, fibroblast growth factor-, and low-density lipoprotein-receptors (EGFR, FGFR1, and LDLR). Regulatory proteins including ubiquitin ligase Cbl, the scaffold Grb2, and the mechanoenzyme dynamin2 are also recruited. Disrupting FGFR or EGFR activity with drugs prevents the recruitment of both EGFR and FGFR1. EGF was able to activate FGFR1 phosphorylation. Our data reveals novel co-clustering and activation of receptors and regulatory factors at clathrin-coated sites in response to stimulation by a single growth factor, EGF or FGF. This behavior integrates growth factor signaling and allows for complex responses to extracellular cues and drugs at the plasma membrane of human cells.","PeriodicalId":18735,"journal":{"name":"Molecular Biology of the Cell","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142265312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Amine Maarouf,Fadil Iqbal,Sarvath Sanaullah,Maëlle Locatelli,Andrew T Atanasiu,Daniel Kolbin,Chloé Hommais,Joëlle Mühlemann,Keith Bonin,Kerry Bloom,Jing Liu,Pierre-Alexandre Vidi
{"title":"RAD51 regulates eukaryotic chromatin motions in the absence of DNA damage.","authors":"Amine Maarouf,Fadil Iqbal,Sarvath Sanaullah,Maëlle Locatelli,Andrew T Atanasiu,Daniel Kolbin,Chloé Hommais,Joëlle Mühlemann,Keith Bonin,Kerry Bloom,Jing Liu,Pierre-Alexandre Vidi","doi":"10.1091/mbc.e24-04-0188","DOIUrl":"https://doi.org/10.1091/mbc.e24-04-0188","url":null,"abstract":"In yeasts and higher eukaryotes, chromatin motions may be tuned to genomic functions, with transcriptional activation and the DNA damage response both leading to profound changes in chromatin dynamics. The RAD51 recombinase is a key mediator of chromatin mobility following DNA damage. As functions of RAD51 beyond DNA repair are being discovered, we asked if RAD51 modulates chromatin dynamics in the absence of DNA damage and found that inhibition or depletion of RAD51 alters chromatin motions in undamaged cells. Inhibition of RAD51 increased nucleosome clustering. Predictions from polymer models are that chromatin clusters reduce chain mobility and, indeed, we measured reduced motion of individual chromatin loci in cells treated with a RAD51 inhibitor. This effect was conserved in mammalian cells, yeasts, and plant cells. In contrast, RAD51 depletion or inhibition increased global chromatin motions at the microscale. The results uncover a role for RAD51 in regulating local and global chromatin dynamics independently from DNA damage and highlight the importance of considering different physical scales when studying chromatin dynamics.","PeriodicalId":18735,"journal":{"name":"Molecular Biology of the Cell","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142269415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Michael J Kimmich,Sumana Sundaramurthy,Meaghan A Geary,Leila Lesanpezeshki,Curtis V Yingling,Siva A Vanapalli,Ryan S Littlefield,David Pruyne
{"title":"FHOD-1 and profilin protect sarcomeres against contraction-induced deformation in C. elegans.","authors":"Michael J Kimmich,Sumana Sundaramurthy,Meaghan A Geary,Leila Lesanpezeshki,Curtis V Yingling,Siva A Vanapalli,Ryan S Littlefield,David Pruyne","doi":"10.1091/mbc.e24-04-0145","DOIUrl":"https://doi.org/10.1091/mbc.e24-04-0145","url":null,"abstract":"Formin HOmology Domain 2-containing (FHOD) proteins are a subfamily of actin-organizing formins important for striated muscle development in many animals. We showed previously that absence of the sole FHOD protein, FHOD-1, from Caenorhabditis elegans results in thin body wall muscles with misshapen dense bodies that serve as sarcomere Z-lines. We demonstrate here that mutations predicted to specifically disrupt actin polymerization by FHOD-1 similarly disrupt muscle development, and that FHOD-1 cooperates with profilin PFN-3 for dense body morphogenesis, and with profilins PFN-2 and PFN-3 to promote body wall muscle growth. We further demonstrate that dense bodies in worms lacking FHOD-1 or PFN-2/PFN-3 are less stable than in wild type animals, having a higher proportion of dynamic protein, and becoming distorted by prolonged muscle contraction. We also observe accumulation of actin and actin depolymerization factor/cofilin homolog UNC-60B in body wall muscle of these mutants. Such accumulations may indicate targeted disassembly of thin filaments dislodged from unstable dense bodies, possibly accounting for the abnormally slow growth and reduced body wall muscle strength in fhod-1 mutants. Overall, these results implicate FHOD protein-mediated actin assembly in forming stable sarcomere Z-lines, and identify profilin as a new contributor to FHOD activity in striated muscle development.","PeriodicalId":18735,"journal":{"name":"Molecular Biology of the Cell","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142184289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The prolyl isomerase FKBP11 is a secretory translocon accessory factor.","authors":"Amanda DiGuilio,Ben Cheng,Frank Zhong,Roshan Jha,Yu Wan,Andrei Anghel,Hong Hu,Evgenia Shishkova,Zhe Ji,Joshua J Coon,Robert J Keenan","doi":"10.1091/mbc.e24-07-0305","DOIUrl":"https://doi.org/10.1091/mbc.e24-07-0305","url":null,"abstract":"Eukaryotic cells encode thousands of secretory and membrane proteins, many of which are cotranslationally translocated into or across the endoplasmic reticulum (ER). Nascent polypeptides entering the ER encounter a network of molecular chaperones and enzymes that facilitate their folding. A rate-limiting step for some proteins is the trans-to-cis isomerization of the peptide bond between proline and the residue preceding it. The human ER contains six prolyl isomerases, but the function, organization and substrate range of these proteins is not clear. Here we show that the metazoan-specific, prolyl isomerase FKBP11 binds to ribosome-translocon complexes (RTCs) in the ER membrane, dependent on its single transmembrane domain (TMD) and a conserved, positively charged region at its cytosolic C-terminus. High throughput mRNA sequencing shows selective engagement with ribosomes synthesizing secretory and membrane proteins with long translocated segments, and functional analysis shows reduced stability of two such proteins, EpCAM and PTTG1IP, in cells depleted of FKBP11. We propose that FKBP11 is a translocon accessory factor that acts on a broad range of soluble secretory and transmembrane proteins during their synthesis at the ER.","PeriodicalId":18735,"journal":{"name":"Molecular Biology of the Cell","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142184291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anna Cassidy,Veronica Farmer,Göker Arpağ,Marija Zanic
{"title":"The GTP-tubulin cap is not the determinant of microtubule end stability in cells.","authors":"Anna Cassidy,Veronica Farmer,Göker Arpağ,Marija Zanic","doi":"10.1091/mbc.e24-07-0307","DOIUrl":"https://doi.org/10.1091/mbc.e24-07-0307","url":null,"abstract":"Microtubules are dynamic cytoskeletal polymers essential for cell division, motility, and intracellular transport. Microtubule dynamics are characterized by dynamic instability-the ability of individual microtubules to switch between phases of growth and shrinkage. Dynamic instability can be explained by the GTP-cap model, suggesting that a 'cap' of GTP-tubulin subunits at the growing microtubule end has a stabilizing effect, protecting against microtubule catastrophe-the switch from growth to shrinkage. Although the GTP-cap is thought to protect the growing microtubule end, whether the GTP-cap size affects microtubule stability in cells is not known. Notably, a family of microtubule end-binding proteins, EBs, recognize the nucleotide state of tubulin and display comet-like localization at growing microtubule ends, which can be used as a proxy for the GTP-cap. Here, we employ high spatiotemporal resolution imaging to compare the relationship between EB comet size and microtubule dynamics in interphase LLC-PK1 cells to that measured in vitro. Our data reveal that the GTP-cap size in cells scales with the microtubule growth rate in the same way as in vitro. However, we find that microtubule ends in cells can withstand transition to catastrophe even after the EB comet is lost. Thus, our findings suggest that the presence of the GTP-cap is not the determinant of microtubule end stability in cells.","PeriodicalId":18735,"journal":{"name":"Molecular Biology of the Cell","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142184292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Big1 is a newly identified autophagy regulator that is critical for a fully functional V-ATPase.","authors":"Yuchen Lei,Ying Yang,Zhihai Zhang,Ruoxi Zhang,Xinxin Song,Sami N Malek,Daolin Tang,Daniel J Klionsky","doi":"10.1091/mbc.e24-04-0189","DOIUrl":"https://doi.org/10.1091/mbc.e24-04-0189","url":null,"abstract":"The vacuolar H+-translocating ATPase (V-ATPase) is the major proton pump for intra-organellar acidification. Therefore, the integrity of the V-ATPase is closely associated with cellular homeostasis, and mutations in genes encoding V-ATPase components and assembly factors have been reported in certain types of diseases. For instance, the recurrent mutations of ATP6AP1, a gene encoding a V-ATPase accessory protein, have been associated with cancers and immunodeficiency. With the aim of studying V-ATPase-related mutations using the yeast model system, we report that Big1 is another homolog of ATP6AP1 in yeast cells, and we characterize the role of Big1 in maintaining a fully functional V-ATPase. In addition to its role in acidifying the vacuole or lysosome, our data support the concept that the V-ATPase may function as part of a signaling pathway to regulate macroautophagy/autophagy through a mechanism that is independent from Tor/MTOR.","PeriodicalId":18735,"journal":{"name":"Molecular Biology of the Cell","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142184290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}