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Elias RD, Zhu Y, Su Q, Ghirlando R, Zhang J, Deshmukh L. Reversible phase separation of ESCRT protein ALIX through tyrosine phosphorylation. SCIENCE ADVANCES 2023; 9:eadg3913. [PMID: 37450591 PMCID: PMC10348681 DOI: 10.1126/sciadv.adg3913] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 06/14/2023] [Indexed: 07/18/2023]
Abstract
Cytokinetic abscission, the last step of cell division, is regulated by the ESCRT machinery. In response to mitotic errors, ESCRT proteins, namely, ALIX, CHMP4B, and CHMP4C, accumulate in the cytosolic compartments termed "abscission checkpoint bodies" (ACBs) to delay abscission and prevent tumorigenesis. ALIX contributes to the biogenesis and stability of ACBs via an unknown mechanism. We show that ALIX phase separates into nondynamic condensates in vitro and in vivo, mediated by the amyloidogenic portion of its proline-rich domain. ALIX condensates confined CHMP4 paralogs in vitro. These condensates dissolved and reformed upon reversible tyrosine phosphorylation of ALIX, mediated by Src kinase and PTP1B, and sequestration of CHMP4C altered their Src-mediated dissolution. NMR analysis revealed how ALIX triggers the activation of CHMP4 proteins, which is required for successful abscission. These results implicate ALIX's phase separation in the modulation of ACBs. This study also highlights how posttranslational modifications can control protein phase separation.
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Affiliation(s)
- Ruben D. Elias
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yingqi Zhu
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Qi Su
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jin Zhang
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Lalit Deshmukh
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
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Aneskievich BJ, Shamilov R, Vinogradova O. Intrinsic disorder in integral membrane proteins. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2021; 183:101-134. [PMID: 34656327 DOI: 10.1016/bs.pmbts.2021.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The well-defined roles and specific protein-protein interactions of many integral membrane proteins (IMPs), such as those functioning as receptors for extracellular matrix proteins and soluble growth factors, easily align with considering IMP structure as a classical "lock-and-key" concept. Nevertheless, continued advances in understanding protein conformation, such as those which established the widespread existence of intrinsically disordered proteins (IDPs) and especially intrinsically disordered regions (IDRs) in otherwise three-dimensionally organized proteins, call for ongoing reevaluation of transmembrane proteins. Here, we present basic traits of IDPs and IDRs, and, for some select single-span IMPs, consider the potential functional advantages intrinsic disorder might provide and the possible conformational impact of disease-associated mutations. For transmembrane proteins in general, we highlight several investigational approaches, such as biophysical and computational methods, stressing the importance of integrating them to produce a more-complete mechanistic model of disorder-containing IMPs. These procedures, when synergized with in-cell assessments, will likely be key in translating in silico and in vitro results to improved understanding of IMP conformational flexibility in normal cell physiology as well as disease, and will help to extend their potential as therapeutic targets.
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Affiliation(s)
- Brian J Aneskievich
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, United States
| | - Rambon Shamilov
- Graduate Program in Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, United States
| | - Olga Vinogradova
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, United States.
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Nguyen K, Puthenveetil R, Vinogradova O. Investigation of the adaptor protein PLIC-2 in multiple pathways. Biochem Biophys Rep 2017; 9:341-348. [PMID: 28286874 PMCID: PMC5341616 DOI: 10.1016/j.bbrep.2017.01.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
PLIC, Protein Linking IAP (CD47) to Cytoskeleton, have long since been implicated in connecting the extracellular membrane to the intracellular cell cytoskeleton. This phenomenon is supposedly achieved by bridging a receptor protein CD47 to vimentin, an intermediate filament, which in turn regulates integrin dependent cell spreading. Since the discovery of these proteins, the molecular details of the above-mentioned interactions and the underlying complexes are yet to be characterized. Several independent studies have together emphasized PLIC/Ubiquilin's role in the proteasomal degradation pathway. This seems to be in contrast to the purported initial discovery of PLIC as a cytoskeletal adaptor protein. In an effort to reconcile the different roles associated with the ubiquitous PLIC proteins, we tested the involvement of PLIC-2 both in the proteasomal degradation pathway and as a protein linking the cell cytoskeleton to the cytoplasmic tail of CD47. This was achieved thorough an in vitro investigation of their binding interface using a combination of biophysical techniques. Our results show that the two terminal domains of PLIC-2 interact weakly with each other, while the C-terminal UBA domain interacts strongly with ubiquitin. Interestingly, no perceptible interaction was observed for PLIC-2 with the cytoplasmic tail of CD47 questioning its role as a "PLIC" protein linking the cell membrane to the cytoskeleton.
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Affiliation(s)
- Khiem Nguyen
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut at Storrs, Storrs, CT 06269
| | - Robbins Puthenveetil
- Department of Molecular and Cell Biology, CLAS, University of Connecticut at Storrs, Storrs, CT 06269
| | - Olga Vinogradova
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut at Storrs, Storrs, CT 06269
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Dunker AK, Bondos SE, Huang F, Oldfield CJ. Intrinsically disordered proteins and multicellular organisms. Semin Cell Dev Biol 2014; 37:44-55. [PMID: 25307499 DOI: 10.1016/j.semcdb.2014.09.025] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 09/15/2014] [Accepted: 09/30/2014] [Indexed: 12/12/2022]
Abstract
Intrinsically disordered proteins (IDPs) and IDP regions lack stable tertiary structure yet carry out numerous biological functions, especially those associated with signaling, transcription regulation, DNA condensation, cell division, and cellular differentiation. Both post-translational modifications (PTMs) and alternative splicing (AS) expand the functional repertoire of IDPs. Here we propose that an "IDP-based developmental toolkit," which is comprised of IDP regions, PTMs, especially multiple PTMs, within these IDP regions, and AS events within segments of pre-mRNA that code for these same IDP regions, allows functional diversification and environmental responsiveness for molecules that direct the development of complex metazoans.
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Affiliation(s)
- A Keith Dunker
- Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University Schools of Medicine and Informatics, Indianapolis, IN 46202, United States.
| | - Sarah E Bondos
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843, United States.
| | - Fei Huang
- Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University Schools of Medicine and Informatics, Indianapolis, IN 46202, United States.
| | - Christopher J Oldfield
- Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University Schools of Medicine and Informatics, Indianapolis, IN 46202, United States.
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Uversky VN. The most important thing is the tail: multitudinous functionalities of intrinsically disordered protein termini. FEBS Lett 2013; 587:1891-901. [PMID: 23665034 DOI: 10.1016/j.febslet.2013.04.042] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 04/24/2013] [Accepted: 04/29/2013] [Indexed: 01/29/2023]
Abstract
Many functional proteins do not have well-folded structures in their substantial parts, representing hybrids that possess both ordered and disordered regions. Disorder is unevenly distributed within these hybrid proteins and is typically more common at protein termini. Disordered tails are engaged in a wide range of functions, some of which are unique for termini and cannot be found in other disordered parts of a protein. This review covers some of the key functions of disordered protein termini and emphasizes that these tails are not simple flexible protrusions but are evolved to serve.
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Affiliation(s)
- Vladimir N Uversky
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA.
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Sigalov AB. Uncoupled binding and folding of immune signaling-related intrinsically disordered proteins. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2011; 106:525-36. [DOI: 10.1016/j.pbiomolbio.2011.08.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 08/10/2011] [Indexed: 10/17/2022]
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Shemetov AA, Gusev NB. Biochemical characterization of small heat shock protein HspB8 (Hsp22)-Bag3 interaction. Arch Biochem Biophys 2011; 513:1-9. [PMID: 21767525 DOI: 10.1016/j.abb.2011.06.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 06/25/2011] [Accepted: 06/30/2011] [Indexed: 01/12/2023]
Abstract
Interaction of human Bag3 with small heat shock proteins HspB6, HspB8 and its K141E mutant was analyzed by different biochemical methods. The data of size-exclusion chromatography indicate that the wild type HspB8 forms tight complexes with Bag3. K141E mutant of HspB8 and especially HspB6 weaker interact with Bag3. The data of chemical crosslinking and analytical ultracentrifugation indicate that in vitro the stoichiometry of complexes formed by HspB8 and Bag3 is variable and is dependent on concentration of protein partners. Interaction of Bag3 and HspB8 is accompanied by increase of thermal stability measured by intrinsic tryptophan fluorescence and increased resistance to limited chymotrypsinolysis. The data of size-exclusion chromatography, analytical ultracentrifugation and limited proteolysis indicate that Bag3 belongs to the group of intrinsically disordered proteins. It is supposed that having unordered structure Bag3 might weakly interact with different small heat shock proteins which recognize unfolded proteins and this interaction is especially strong with intrinsically disordered HspB8. The complexes formed by Bag3 and HspB8 might have variable stoichiometry and can participate in different processes including clearing of the cell from improperly folded proteins.
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Affiliation(s)
- Anton A Shemetov
- Department of Biochemistry, School of Biology, Moscow State University, Russian Federation
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Full-length L1CAM and not its Δ2Δ27 splice variant promotes metastasis through induction of gelatinase expression. PLoS One 2011; 6:e18989. [PMID: 21541352 PMCID: PMC3081839 DOI: 10.1371/journal.pone.0018989] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Accepted: 03/24/2011] [Indexed: 01/09/2023] Open
Abstract
Tumour-specific splicing is known to contribute to cancer progression. In the case of the L1 cell adhesion molecule (L1CAM), which is expressed in many human tumours and often linked to bad prognosis, alternative splicing results in a full-length form (FL-L1CAM) and a splice variant lacking exons 2 and 27 (SV-L1CAM). It has not been elucidated so far whether SV-L1CAM, classically considered as tumour-associated, or whether FL-L1CAM is the metastasis-promoting isoform. Here, we show that both variants were expressed in human ovarian carcinoma and that exposure of tumour cells to pro-metastatic factors led to an exclusive increase of FL-L1CAM expression. Selective overexpression of one isoform in different tumour cells revealed that only FL-L1CAM promoted experimental lung and/or liver metastasis in mice. In addition, metastasis formation upon up-regulation of FL-L1CAM correlated with increased invasive potential and elevated Matrix metalloproteinase (MMP)-2 and -9 expression and activity in vitro as well as enhanced gelatinolytic activity in vivo. In conclusion, we identified FL-L1CAM as the metastasis-promoting isoform, thereby exemplifying that high expression of a so-called tumour-associated variant, here SV-L1CAM, is not per se equivalent to a decisive role of this isoform in tumour progression.
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Chen MM, Lee CY, Leland HA, Lin GY, Montgomery AM, Silletti S. Inside-out regulation of L1 conformation, integrin binding, proteolysis, and concomitant cell migration. Mol Biol Cell 2010; 21:1671-85. [PMID: 20335502 PMCID: PMC2869374 DOI: 10.1091/mbc.e09-10-0900] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The ectodomain structure and function of the neural cell adhesion molecule L1 is shown to be regulated by the intracellular phosphorylation of a novel threonine, T1172. In pancreatic cancer cells, T1172 exhibits steady-state saturated phosphorylation, an event regulated by CKII and PKC, and which further regulates cell migration. Previous reports on the expression of the cell adhesion molecule L1 in pancreatic ductal adenocarcinoma (PDAC) cells range from absent to high. Our data demonstrate that L1 is expressed in poorly differentiated PDAC cells in situ and that threonine-1172 (T1172) in the L1 cytoplasmic domain exhibits steady-state saturated phosphorylation in PDAC cells in vitro and in situ. In vitro studies support roles for casein kinase II and PKC in this modification, consistent with our prior studies using recombinant proteins. Importantly, T1172 phosphorylation drives, or is associated with, a change in the extracellular structure of L1, consistent with a potential role in regulating the shift between the closed conformation and the open, multimerized conformation of L1. We further demonstrate that these distinct conformations exhibit differential binding to integrins αvβ3 and αvβ5 and that T1172 regulates cell migration in a matrix-specific manner and is required for a disintegrin and metalloproteinase-mediated shedding of the L1 ectodomain that has been shown to regulate cell migration. These data define a specific role for T1172 of L1 in regulating aspects of pancreatic adenocarcinoma cell phenotype and suggest the need for further studies to elucidate the specific ramifications of L1 expression and T1172 phosphorylation in the pathobiology of pancreatic cancer.
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Affiliation(s)
- Maxine M Chen
- Moores Cancer Center and Department of Pathology, University of California, San Diego, La Jolla, CA 92093, USA
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Chen MM, Leland HA, Lee CY, Silletti S. Tyrosine and serine phosphorylation regulate the conformation and subsequent threonine phosphorylation of the L1 cytoplasmic domain. Biochem Biophys Res Commun 2009; 389:257-64. [PMID: 19720049 DOI: 10.1016/j.bbrc.2009.08.143] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 08/22/2009] [Indexed: 12/20/2022]
Abstract
Previously we identified threonine-1172 (T1172) in the cytoplasmic domain of the cell adhesion molecule L1 as phosphorylated in pancreatic cancer cells. Although both CKII- and PKC-blockade suppressed this modification, only CKII was capable of phosphorylating T1172 of a recombinant L1 cytoplasmic domain, suggesting the requirement for additional events to facilitate availability of T1172 to PKC. In this study, we demonstrate that the region around T1172 exists in distinct conformations based on both T1172 phosphorylation and the integrity of surrounding residues. We further demonstrate the role of membrane-proximal and membrane-distal residues in regulating cytoplasmic domain conformation, and that modification of 3 of the 4 tyrosines in the L1 cytoplasmic domain promote conformational changes that facilitate other events. In particular, phenylalanine-substitution of tyrosine-1151 or tyrosine-1229 promote opening up of the cytoplasmic domain in a manner that facilitates phosphorylation of the other 3 tyrosines, as well as phosphorylation of T1172 by PKCalpha. Importantly, we show that phosphorylation of serine-1181 is required for T1172 phosphorylation by CKII. These data define a specific role for secondary structure in regulating the availability of T1172 that facilitates phosphorylation by PKC.
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Affiliation(s)
- Maxine M Chen
- Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093-0803, USA
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Abstract
The L1 family of CAMs (cell adhesion molecules) has long aroused the interest of researchers, but primarily the extracellular interactions of these proteins have been elucidated. More recently, attention has turned to the intracellular signalling potentiated by transmembrane proteins and the cytoplasmic proteins with which they can interact. The present review brings up to date the current body of published knowledge for the intracellular interactions of L1-CAM family proteins and the potential importance of these interactions for the mechanisms of L1-CAM action.
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