1
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Jijumon AS, Krishnan A, Janke C. A Platform for Medium-Throughput Cell-Free Analyses of Microtubule-Interacting Proteins Using Mammalian Cell Lysates. Curr Protoc 2024; 4:e1070. [PMID: 38865215 DOI: 10.1002/cpz1.1070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
The microtubule (MT) cytoskeleton performs a variety of functions in cell division, cell architecture, neuronal differentiation, and ciliary beating. These functions are controlled by proteins that directly interact with MTs, commonly referred to as microtubule-associated proteins (MAPs). Out of the many proteins reported interact with MTs, only a some have been biochemically and functionally characterized so far. One of the limitations of classical in vitro assays and single-MT reconstitution approaches is that they are typically performed with purified proteins. As purification of proteins can be difficult and time-consuming, many previous studies have only focused on a few proteins, while systematic analyses of many different proteins by in vitro reconstitution assays were not possible. Here we present a detailed protocol using lysates of mammalian cells instead of purified proteins that overcomes this limitation. Those lysates contain all molecular components required for in vitro MT reconstitution including the endogenous tubulin and the recombinant MAPs, which form MT assemblies upon the injection of the lysates into a microscopy chamber. This allows to directly observe the dynamic behavior of growing MTs, as well as the fluorescently labeled associated proteins by total internal reflection fluorescence (TIRF) microscopy. Strikingly, all proteins tested so far were functional in our approach, thus providing the possibility to test virtually any protein of interest. This also opens the possibility to screen the impact of patient mutations on the MT binding behavior of MAPs in a medium-throughput manner. In addition, the lysate approach can easily be adapted to other applications that have predominantly been performed with purified proteins so far, such as investigating other cytoskeletal systems and cytoskeletal crosstalk, or to study structures of MAPs bound to MTs by cryo-electron microscopy. Our approach is thus a versatile, expandable, and easy-to-use method to characterize the impact of a broad spectrum of proteins on cytoskeletal behavior and function. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Preparation of lysates of human cells for TIRF reconstitution assays Basic Protocol 2: Quantification of GFP-tagged MAP concentration in cell lysates Support Protocol 1: Purification of KIF5B(N555/T92A) (dead kinesin) protein for TIRF reconstitution assays Support Protocol 2: Preparation of GMPCPP MT seeds for TIRF reconstitution assays Basic Protocol 3: TIRF-based MT-MAP reconstitution assays using cell lysates.
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Affiliation(s)
- A S Jijumon
- Institut Curie, Université PSL, CNRS UMR3348, Orsay, France
- Université Paris-Saclay, CNRS UMR3348, Orsay, France
- Current affiliation: Stanford University, Stanford, California
| | - Arya Krishnan
- Institut Curie, Université PSL, CNRS UMR3348, Orsay, France
- Université Paris-Saclay, CNRS UMR3348, Orsay, France
| | - Carsten Janke
- Institut Curie, Université PSL, CNRS UMR3348, Orsay, France
- Université Paris-Saclay, CNRS UMR3348, Orsay, France
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2
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Liu J, Ding C, Liu X, Kang Q. Cytoskeletal Protein 4.1R in Health and Diseases. Biomolecules 2024; 14:214. [PMID: 38397451 PMCID: PMC10887211 DOI: 10.3390/biom14020214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 02/02/2024] [Accepted: 02/07/2024] [Indexed: 02/25/2024] Open
Abstract
The protein 4.1R is an essential component of the erythrocyte membrane skeleton, serving as a key structural element and contributing to the regulation of the membrane's physical properties, including mechanical stability and deformability, through its interaction with spectrin-actin. Recent research has uncovered additional roles of 4.1R beyond its function as a linker between the plasma membrane and the membrane skeleton. It has been found to play a crucial role in various biological processes, such as cell fate determination, cell cycle regulation, cell proliferation, and cell motility. Additionally, 4.1R has been implicated in cancer, with numerous studies demonstrating its potential as a diagnostic and prognostic biomarker for tumors. In this review, we provide an updated overview of the gene and protein structure of 4.1R, as well as its cellular functions in both physiological and pathological contexts.
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Affiliation(s)
- Jiaojiao Liu
- School of Life Science, Zhengzhou University, Zhengzhou 450001, China
| | - Cong Ding
- Children's Hospital Affiliated of Zhengzhou University, Zhengzhou 450018, China
| | - Xin Liu
- School of Life Science, Zhengzhou University, Zhengzhou 450001, China
| | - Qiaozhen Kang
- School of Life Science, Zhengzhou University, Zhengzhou 450001, China
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3
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Yang Q, Liu J, Wang Z. 4.1N-Mediated Interactions and Functions in Nerve System and Cancer. Front Mol Biosci 2021; 8:711302. [PMID: 34589518 PMCID: PMC8473747 DOI: 10.3389/fmolb.2021.711302] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 08/16/2021] [Indexed: 01/05/2023] Open
Abstract
Scaffolding protein 4.1N is a neuron-enriched 4.1 homologue. 4.1N contains three conserved domains, including the N-terminal 4.1-ezrin-radixin-moesin (FERM) domain, internal spectrin–actin–binding (SAB) domain, and C-terminal domain (CTD). Interspersed between the three domains are nonconserved domains, including U1, U2, and U3. The role of 4.1N was first reported in the nerve system. Then, extensive studies reported the role of 4.1N in cancers and other diseases. 4.1N performs numerous vital functions in signaling transduction by interacting, locating, supporting, and coordinating different partners and is involved in the molecular pathogenesis of various diseases. In this review, recent studies on the interactions between 4.1N and its contactors (including the α7AChr, IP3R1, GluR1/4, GluK1/2/3, mGluR8, KCC2, D2/3Rs, CASK, NuMA, PIKE, IP6K2, CAM 1/3, βII spectrin, flotillin-1, pp1, and 14-3-3) and the 4.1N-related biological functions in the nerve system and cancers are specifically and comprehensively discussed. This review provides critical detailed mechanistic insights into the role of 4.1N in disease relationships.
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Affiliation(s)
- Qin Yang
- Molecular Biology Research Center & Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China.,School of Medical Laboratory, Shao Yang University, Shaoyang, China
| | - Jing Liu
- Molecular Biology Research Center & Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Zi Wang
- Molecular Biology Research Center & Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, China
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4
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Huang SC, Vu LV, Yu FH, Nguyen DT, Benz EJ. Multifunctional protein 4.1R regulates the asymmetric segregation of Numb during terminal erythroid maturation. J Biol Chem 2021; 297:101051. [PMID: 34364872 PMCID: PMC8408529 DOI: 10.1016/j.jbc.2021.101051] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 07/28/2021] [Accepted: 08/04/2021] [Indexed: 10/25/2022] Open
Abstract
The asymmetric cell division of stem or progenitor cells generates daughter cells with distinct fates that balance proliferation and differentiation. Asymmetric segregation of Notch signaling regulatory protein Numb plays a crucial role in cell diversification. However, the molecular mechanism remains unclear. Here, we examined the unequal distribution of Numb in the daughter cells of murine erythroleukemia cells (MELCs) that undergo DMSO-induced erythroid differentiation. In contrast to the cytoplasmic localization of Numb during uninduced cell division, Numb is concentrated at the cell boundary in interphase, near the one-spindle pole in metaphase, and is unequally distributed to one daughter cell in anaphase in induced cells. The inheritance of Numb guides this daughter cell toward erythroid differentiation while the other cell remains a progenitor cell. Mitotic spindle orientation, critical for distribution of cell fate determinants, requires complex communication between the spindle microtubules and the cell cortex mediated by the NuMA-LGN-dynein/dynactin complex. Depletion of each individual member of the complex randomizes the position of Numb relative to the mitotic spindle. Gene replacement confirms that multifunctional erythrocyte protein 4.1R (4.1R) functions as a member of the NuMA-LGN-dynein/dynactin complex and is necessary for regulating spindle orientation, in which interaction between 4.1R and NuMA plays an important role. These results suggest that mispositioning of Numb is the result of spindle misorientation. Finally, disruption of the 4.1R-NuMA-LGN complex increases Notch signaling and decreases the erythroblast population. Together, our results identify a critical role for 4.1R in regulating the asymmetric segregation of Numb to mediate erythropoiesis.
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Affiliation(s)
- Shu-Ching Huang
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA; Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA; Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA.
| | - Long V Vu
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Faye H Yu
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Dan T Nguyen
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Edward J Benz
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA; Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA; Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA; Department of Pediatrics and Genetics, Harvard Medical School, Boston, Massachusetts, USA; Leukemia Program, Dana-Farber/Harvard Cancer Center, Boston, Massachusetts, USA
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5
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Rangel L, Lospitao E, Ruiz-Sáenz A, Alonso MA, Correas I. Alternative polyadenylation in a family of paralogous EPB41 genes generates protein 4.1 diversity. RNA Biol 2016; 14:236-244. [PMID: 27981895 DOI: 10.1080/15476286.2016.1270003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Alternative polyadenylation (APA) is a step in mRNA 3'-end processing that contributes to the complexity of the transcriptome by generating isoforms that differ in either their coding sequence or their 3'-untranslated regions (UTRs). The EPB41 genes, EPB41, EPB41L2, EPB41L3 and EPB41L1, encode an impressively complex array of structural adaptor proteins (designated 4.1R, 4.1G, 4.1B and 4.1N, respectively) by using alternative transcriptional promoters and tissue-specific alternative pre-mRNA splicing. The great variety of 4.1 proteins mainly results from 5'-end and internal processing of the EPB41 pre-mRNAs. Thus, 4.1 proteins can vary in their N-terminal extensions but all contain a highly homologous C-terminal domain (CTD). Here we study a new group of EPB41-related mRNAs that originate by APA and lack the exons encoding the CTD characteristic of prototypical 4.1 proteins, thereby encoding a new type of 4.1 protein. For the EPB41 gene, this type of processing was observed in all 11 human tissues analyzed. Comparative genomic analysis of EPB41 indicates that APA is conserved in various mammals. In addition, we show that APA also functions for the EPB41L2, EPB41L3 and EPB41L1 genes, but in a more restricted manner in the case of the latter 2 than it does for the EPB41 and EPB41L2 genes. Our study shows alternative polyadenylation to be an additional mechanism for the generation of 4.1 protein diversity in the already complex EPB41-related genes. Understanding the diversity of EPB41 RNA processing is essential for a full appreciation of the many 4.1 proteins expressed in normal and pathological tissues.
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Affiliation(s)
- Laura Rangel
- a Departamento de Biología Molecular , Universidad Autónoma de Madrid (UAM), Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas (CSIC), Nicolás Cabrera , Cantoblanco, Madrid , Spain
| | - Eva Lospitao
- a Departamento de Biología Molecular , Universidad Autónoma de Madrid (UAM), Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas (CSIC), Nicolás Cabrera , Cantoblanco, Madrid , Spain
| | - Ana Ruiz-Sáenz
- a Departamento de Biología Molecular , Universidad Autónoma de Madrid (UAM), Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas (CSIC), Nicolás Cabrera , Cantoblanco, Madrid , Spain
| | - Miguel A Alonso
- a Departamento de Biología Molecular , Universidad Autónoma de Madrid (UAM), Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas (CSIC), Nicolás Cabrera , Cantoblanco, Madrid , Spain
| | - Isabel Correas
- a Departamento de Biología Molecular , Universidad Autónoma de Madrid (UAM), Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas (CSIC), Nicolás Cabrera , Cantoblanco, Madrid , Spain
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6
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Ruiz-Saenz A, van Haren J, Sayas CL, Rangel L, Demmers J, Millán J, Alonso MA, Galjart N, Correas I. Protein 4.1R binds to CLASP2 and regulates dynamics, organization and attachment of microtubules to the cell cortex. J Cell Sci 2013; 126:4589-601. [PMID: 23943871 DOI: 10.1242/jcs.120840] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The microtubule (MT) cytoskeleton is essential for many cellular processes, including cell polarity and migration. Cortical platforms, formed by a subset of MT plus-end-tracking proteins, such as CLASP2, and non-MT binding proteins such as LL5β, attach distal ends of MTs to the cell cortex. However, the mechanisms involved in organizing these platforms have not yet been described in detail. Here we show that 4.1R, a FERM-domain-containing protein, interacts and colocalizes with cortical CLASP2 and is required for the correct number and dynamics of CLASP2 cortical platforms. Protein 4.1R also controls binding of CLASP2 to MTs at the cell edge by locally altering GSK3 activity. Furthermore, in 4.1R-knockdown cells MT plus-ends were maintained for longer in the vicinity of cell edges, but instead of being tethered to the cell cortex, MTs continued to grow, bending at cell margins and losing their radial distribution. Our results suggest a previously unidentified role for the scaffolding protein 4.1R in locally controlling CLASP2 behavior, CLASP2 cortical platform turnover and GSK3 activity, enabling correct MT organization and dynamics essential for cell polarity.
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Affiliation(s)
- Ana Ruiz-Saenz
- Centro de Biología Molecular Severo Ochoa and Departamento de Biología Molecular, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid (CSIC and UAM), Nicolás Cabrera 1, 28049 Madrid, Spain
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7
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Chen L, Hughes RA, Baines AJ, Conboy J, Mohandas N, An X. Protein 4.1R regulates cell adhesion, spreading, migration and motility of mouse keratinocytes by modulating surface expression of beta1 integrin. J Cell Sci 2011; 124:2478-87. [PMID: 21693581 DOI: 10.1242/jcs.078170] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Protein 4.1R is a membrane-cytoskeleton adaptor protein that has diverse roles in controlling the cell surface expression and/or function of transmembrane proteins, and in organizing F-actin. 4.1R is expressed in keratinocytes, but its role in these cells has not been explored. Here, we have investigated the role of 4.1R in skin using 4.1R(-/-) mice. Cell adhesion, spreading, migration and motility were significantly impaired in 4.1R(-/-) keratinocytes, and 4.1R(-/-) mice exhibited defective epidermal wound healing. Cultured 4.1R(-/-) keratinocytes on fibronectin failed to form actin stress fibres and focal adhesions. Furthermore, in the absence of 4.1R, the surface expression, and consequently the activity of β1 integrin were reduced. These data enabled the identification of a functional role for protein 4.1R in keratinocytes by modulating the surface expression of β1 integrin, possibly through a direct association between 4.1R and β1 integrin.
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Affiliation(s)
- Lixiang Chen
- Red Cell Physiology Laboratory, New York Blood Center, New York, NY 10065, USA
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8
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Lack of protein 4.1G causes altered expression and localization of the cell adhesion molecule nectin-like 4 in testis and can cause male infertility. Mol Cell Biol 2011; 31:2276-86. [PMID: 21482674 DOI: 10.1128/mcb.01105-10] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Protein 4.1G is a member of the protein 4.1 family, which in general serves as adaptors linking transmembrane proteins to the cytoskeleton. 4.1G is thought to be widely expressed in many cells and tissues, but its function remains largely unknown. To explore the function of 4.1G in vivo, we generated 4.1G(-/-) mice and bred the mice in two backgrounds: C57BL/6 (B6) and 129/Sv (129) hybrids (B6-129) and inbred B6. Although the B6 4.1G(-/-) mice showed no obvious abnormalities, deficiency of 4.1G in B6-129 hybrids was associated with male infertility. Histological examinations of these 4.1G(-/-) mice revealed atrophy, impaired cell-cell contact and sloughing off of spermatogenic cells in seminiferous epithelium, and lack of mature spermatids in the epididymis. Ultrastructural examination revealed enlarged intercellular spaces between spermatogenic and Sertoli cells as well as the spermatid deformities. At the molecular level, 4.1G is associated with the nectin-like 4 (NECL4) adhesion molecule. Importantly, the expression of NECL4 was decreased, and the localization of NECL4 was altered in 4.1G(-/-) testis. Thus, our findings imply that 4.1G plays a role in spermatogenesis by mediating cell-cell adhesion between spermatogenic and Sertoli cells through its interaction with NECL4 on Sertoli cells. Additionally, the finding that infertility is present in B6-129 but not on the B6 background suggests the presence of a major modifier gene(s) that influences 4.1G function and is associated with male infertility.
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9
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Mattagajasingh SN, Huang SC, Benz EJ. Inhibition of protein 4.1 R and NuMA interaction by mutagenization of their binding-sites abrogates nuclear localization of 4.1 R. Clin Transl Sci 2010; 2:102-11. [PMID: 20443879 DOI: 10.1111/j.1752-8062.2008.00087.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Protein 4.1R(4.1R) is a multifunctional structural protein recently implicated in nuclear assembly and cell division. We earlier demonstrated that 4.1R forms a multiprotein complex with mitotic spindle and spindle pole organizing proteins, such as NuMA, dynein, and dynactin, by binding to residues 1788-1810 of NuMA through amino acids encoded by exons 20 and 21 in 24 kD domain. Employing random-and site-directed mutagenesis combined with glycine- and alanine-scanning, we have identified amino acids of 4.1 R and NuMA that sustain their interaction, and have analyzed the effect of mutating the binding sites on their intracellular colocalization. We found that V762, V765, and V767 of 4.1 R, and 11800, 11801,11803, Tl 804, and M1805 of NuMA are necessary for their interaction. GST-fusion peptides of the 4.1R24 kD domain bound to residues 1785-2115 of NuMA in in vitro binding assays, but the binding was inhibited by alanine substitutions of V762, V765, and V767 of 4.1 R, or residues 1800-1805 of NuMA. Additionally, expression of variants of 4.1 R or NuMA that inhibit their in vitro binding also abrogated nuclear localization of 4.1 Rand colocalization with NuMA. Our findings suggest a crucial role of 4.1 R/NuMA interaction in localization and function of 4.1 R in the nucleus.
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10
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Shen E, Lei Y, Liu Q, Zheng Y, Song C, Marc J, Wang Y, Sun L, Liang Q. Identification and characterization of INMAP, a novel interphase nucleus and mitotic apparatus protein that is involved in spindle formation and cell cycle progression. Exp Cell Res 2009; 315:1100-16. [PMID: 19331820 DOI: 10.1016/j.yexcr.2009.01.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2008] [Revised: 01/20/2009] [Accepted: 01/20/2009] [Indexed: 02/07/2023]
Abstract
A novel protein that associates with interphase nucleus and mitotic apparatus (INMAP) was identified by screening HeLa cDNA expression library with an autoimmune serum followed by tandem mass spectrometry. Its complete cDNA sequence of 1.818 kb encodes 343 amino acids with predicted molecular mass of 38.2 kDa and numerous phosphorylation sites. The sequence is identical with nucleotides 1-1800 bp of an unnamed gene (GenBank accession no. 7022388) and highly homologous with the 3'-terminal sequence of POLR3B. A monoclonal antibody against INMAP reacted with similar proteins in S. cerevisiae, Mel and HeLa cells, suggesting that it is a conserved protein. Confocal microscopy using either GFP-INMAP fusion protein or labeling with the monoclonal antibody revealed that the protein localizes as distinct dots in the interphase nucleus, but during mitosis associates closely with the spindle. Double immunolabeling using specific antibodies showed that the INMAP co-localizes with alpha-tubulin, gamma-tubulin, and NuMA. INMAP also co-immunoprecipitated with these proteins in their native state. Stable overexpression of INMAP in HeLa cell lines leads to defects in the spindle, mitotic arrest, formation of polycentrosomal and multinuclear cells, inhibition of growth, and apoptosis. We propose that INMAP is a novel protein that plays essential role in spindle formation and cell-cycle progression.
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Affiliation(s)
- Enzhi Shen
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Sciences, Beijing Normal University, Beijing 100875, PR China
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11
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Mattagajasingh SN, Huang SC, Benz EJ. Inhibition of Protein 4.1 R and NuMA Interaction by Mutagenization of Their Binding-Sites Abrogates Nuclear Localization of 4.1 R. Clin Transl Sci 2009. [DOI: 10.1111/j.1752-8062.2009.00087.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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12
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Seo PS, Jeong JJ, Zeng L, Takoudis CG, Quinn BJ, Khan AA, Hanada T, Chishti AH. Alternatively spliced exon 5 of the FERM domain of protein 4.1R encodes a novel binding site for erythrocyte p55 and is critical for membrane targeting in epithelial cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1793:281-9. [PMID: 18952129 DOI: 10.1016/j.bbamcr.2008.09.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 09/12/2008] [Accepted: 09/17/2008] [Indexed: 01/18/2023]
Abstract
Direct physical linkage of MAGUKs to the actin cytoskeleton was first established by the interaction of erythrocyte p55 with the FERM domain of protein 4.1R. Subsequently, it was reported that p55 binds to a 51-amino acid peptide, encoded by exon 10, located within the FERM domain of protein 4.1R. In this study, we investigated the nature of the p55-FERM domain binding interface and show that p55 binds to a second 35-amino acid peptide, encoded by an alternatively spliced exon 5, located within the FERM domain of protein 4.1R. Competition and Surface Plasmon Resonance-binding measurements suggest that the peptides encoded by exons 5 and 10 bind to independent sites within the D5 domain of p55. Interestingly, the full length 135 kDa isoform of protein 4.1R containing both exons 5 and 10 was targeted exclusively to the plasma membrane of epithelial cells whereas the same isoform without exon 5 completely lost its membrane localization capacity. Together, these results indicate that p55 binds to two distinct sites within the FERM domain, and the alternatively spliced exon 5 is necessary for the membrane targeting of protein 4.1R in epithelial cells. Since sequences similar to the exon 5-peptide of protein 4.1R and D5 domain of p55 are conserved in many proteins, our findings suggest that a similar mechanism may govern the membrane targeting of other FERM domain containing proteins.
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Affiliation(s)
- Pil-Soo Seo
- Department of Pharmacology, UIC Cancer Center, University of Illinois College of Medicine, Chicago, IL 60612, USA
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13
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Krauss SW, Spence JR, Bahmanyar S, Barth AIM, Go MM, Czerwinski D, Meyer AJ. Downregulation of protein 4.1R, a mature centriole protein, disrupts centrosomes, alters cell cycle progression, and perturbs mitotic spindles and anaphase. Mol Cell Biol 2008; 28:2283-94. [PMID: 18212055 PMCID: PMC2268423 DOI: 10.1128/mcb.02021-07] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Accepted: 01/08/2008] [Indexed: 01/11/2023] Open
Abstract
Centrosomes nucleate and organize interphase microtubules and are instrumental in mitotic bipolar spindle assembly, ensuring orderly cell cycle progression with accurate chromosome segregation. We report that the multifunctional structural protein 4.1R localizes at centrosomes to distal/subdistal regions of mature centrioles in a cell cycle-dependent pattern. Significantly, 4.1R-specific depletion mediated by RNA interference perturbs subdistal appendage proteins ninein and outer dense fiber 2/cenexin at mature centrosomes and concomitantly reduces interphase microtubule anchoring and organization. 4.1R depletion causes G(1) accumulation in p53-proficient cells, similar to depletion of many other proteins that compromise centrosome integrity. In p53-deficient cells, 4.1R depletion delays S phase, but aberrant ninein distribution is not dependent on the S-phase delay. In 4.1R-depleted mitotic cells, efficient centrosome separation is reduced, resulting in monopolar spindle formation. Multipolar spindles and bipolar spindles with misaligned chromatin are also induced by 4.1R depletion. Notably, all types of defective spindles have mislocalized NuMA (nuclear mitotic apparatus protein), a 4.1R binding partner essential for spindle pole focusing. These disruptions contribute to lagging chromosomes and aberrant microtubule bridges during anaphase/telophase. Our data provide functional evidence that 4.1R makes crucial contributions to the structural integrity of centrosomes and mitotic spindles which normally enable mitosis and anaphase to proceed with the coordinated precision required to avoid pathological events.
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Affiliation(s)
- Sharon Wald Krauss
- Department of Cell Biology and Imaging, University of California-LBNL, 1 Cyclotron Road, MS 74-157, Berkeley, CA 94720, USA
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14
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Rizzolio F, Sala C, Alboresi S, Bione S, Gilli S, Goegan M, Pramparo T, Zuffardi O, Toniolo D. Epigenetic control of the critical region for premature ovarian failure on autosomal genes translocated to the X chromosome: a hypothesis. Hum Genet 2007; 121:441-50. [PMID: 17265046 DOI: 10.1007/s00439-007-0329-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Accepted: 01/08/2007] [Indexed: 11/28/2022]
Abstract
Chromosomal rearrangements in Xq are frequently associated to premature ovarian failure (POF) and have contributed to define a POF "critical region" from Xq13.3 to Xq26. Search for X-linked genes responsible for the phenotype has been elusive as most rearrangements did not interrupt genes and many were mapped to gene deserts. We now report that ovary-expressed genes flanked autosomal breakpoints in four POF cases analyzed whose X chromosome breakpoints interrupted a gene poor region in Xq21, where no ovary-expressed candidate genes could be found. We also show that the global down regulation in the oocyte and up regulation in the ovary of X-linked genes compared to the autosomes is mainly due to genes in the POF "critical region". We thus propose that POF, in X;autosome balanced translocations, may not only be caused by haploinsufficiency, but also by a oocyte-specific position effect on autosomal genes, dependent on dosage compensation mechanisms operating on the active X chromosome in mammals.
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Affiliation(s)
- Flavio Rizzolio
- Department of Molecular Biology and Functional Genomics, San Raffaele Scientific Institute, Milan, Italy
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Johansen KM, Johansen J. Cell and Molecular Biology of the Spindle Matrix. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 263:155-206. [PMID: 17725967 DOI: 10.1016/s0074-7696(07)63004-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The concept of a spindle matrix has long been proposed to account for incompletely understood features of microtubule spindle dynamics and force production during mitosis. In its simplest formulation, the spindle matrix is hypothesized to provide a stationary or elastic molecular matrix that can provide a substrate for motor molecules to interact with during microtubule sliding and which can stabilize the spindle during force production. Although this is an attractive concept with the potential to greatly simplify current models of microtubule spindle behavior, definitive evidence for the molecular nature of a spindle matrix or for its direct role in microtubule spindle function has been lagging. However, as reviewed here multiple studies spanning the evolutionary spectrum from lower eukaryotes to vertebrates have provided new and intriguing evidence that a spindle matrix may be a general feature of mitosis.
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Affiliation(s)
- Kristen M Johansen
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA
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16
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Pérez-Ferreiro CM, Lospitao E, Correas I. Protein 4.1R self-association: identification of the binding domain. Biochem J 2006; 400:457-65. [PMID: 16881872 PMCID: PMC1698608 DOI: 10.1042/bj20060644] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Erythroid protein 4.1 (4.1R) stabilizes the spectrin-actin network and anchors it to the plasma membrane. To contribute to the characterization of non-erythroid protein 4.1R, we used sedimentation, pull-down and co-immunoprecipitation assays to investigate the ability of protein 4.1R to establish inter-/intra-molecular associations. We demonstrated that the small 4.1R isoforms of 60 kDa (4.1R60), but not the larger isoforms of 80 and 135 kDa (4.1R80 and 4.1R135), were self-associated, and that a domain contained in all 4.1R isoforms, the core region, was responsible for 4.1R self-association. Results from denaturing-renaturing experiments, in which an initially non-self-associated 4.1R80 isoform became self-associated, suggested that an initially hidden core region was subsequently exposed. This hypothesis was supported by results from pull-down assays, which showed that the core region interacted with the N-terminal end of the FERM (4.1, ezrin, radixin, moesin) domain that is present in 4.1R80 and 4.1R135 isoforms but absent from 4.1R60 isoforms. Consistently, 4.1R80 isoforms bound neither to each other nor to 4.1R60 isoforms. We propose that 4.1R60 isoforms are constitutively self-associated, whereas 4.1R80 and 4.1R135 self-association is prevented by intramolecular interactions.
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Affiliation(s)
- Carmen M Pérez-Ferreiro
- Departamento de Biología Molecular, CBMSO (Centro de Biología Molecular Severo Ochoa), UAM/CSIC, Cantoblanco, E-28049 Madrid, Spain.
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Mburu P, Kikkawa Y, Townsend S, Romero R, Yonekawa H, Brown SDM. Whirlin complexes with p55 at the stereocilia tip during hair cell development. Proc Natl Acad Sci U S A 2006; 103:10973-8. [PMID: 16829577 PMCID: PMC1544159 DOI: 10.1073/pnas.0600923103] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Hearing in mammals depends upon the proper development of actin-filled stereocilia at the hair cell surface in the inner ear. Whirlin, a PDZ domain-containing protein, is expressed at stereocilia tips and, by virtue of mutations in the whirlin gene, is known to play a key role in stereocilia development. We show that whirlin interacts with the membrane-associated guanylate kinase (MAGUK) protein, erythrocyte protein p55 (p55). p55 is expressed in outer hair cells in long stereocilia that make up the stereocilia bundle as well as surrounding shorter stereocilia structures. p55 interacts with protein 4.1R in erythrocytes, and we find that 4.1R is also expressed in stereocilia structures with an identical pattern to p55. Mutations in the whirlin gene (whirler) and in the myosin XVa gene (shaker2) affect stereocilia development and lead to early ablation of p55 and 4.1R labeling of stereocilia. The related MAGUK protein Ca2+-calmodulin serine kinase (CASK) is also expressed in stereocilia in both outer and inner hair cells, where it is confined to the stereocilia bundle. CASK interacts with protein 4.1N in neuronal tissue, and we find that 4.1N is expressed in stereocilia with an identical pattern to CASK. Unlike p55, CASK labeling shows little diminution of labeling in the whirler mutant and is unaffected in the shaker2 mutant. Similarly, expression of 4.1N in stereocilia is unaltered in whirler and shaker2 mutants. p55 and protein 4.1R form complexes critical for actin cytoskeletal assembly in erythrocytes, and the interaction of whirlin with p55 indicates it plays a similar role in hair cell stereocilia.
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Affiliation(s)
- Philomena Mburu
- *Medical Research Council Mammalian Genetics Unit, Harwell OX11 ORD, United Kingdom; and
| | - Yoshiaki Kikkawa
- Department of Animal Science, Tokyo Metropolitan Institute of Medical Science, 3-18-22, Honkomagome, Bunkyo-ku, Tokyo 113-8613, Japan
| | - Stuart Townsend
- *Medical Research Council Mammalian Genetics Unit, Harwell OX11 ORD, United Kingdom; and
| | - Rosario Romero
- *Medical Research Council Mammalian Genetics Unit, Harwell OX11 ORD, United Kingdom; and
| | - Hiromichi Yonekawa
- Department of Animal Science, Tokyo Metropolitan Institute of Medical Science, 3-18-22, Honkomagome, Bunkyo-ku, Tokyo 113-8613, Japan
| | - Steve D. M. Brown
- *Medical Research Council Mammalian Genetics Unit, Harwell OX11 ORD, United Kingdom; and
- To whom correspondence should be addressed. E-mail:
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18
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Bond J, Woods CG. Cytoskeletal genes regulating brain size. Curr Opin Cell Biol 2006; 18:95-101. [PMID: 16337370 DOI: 10.1016/j.ceb.2005.11.004] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2005] [Accepted: 11/24/2005] [Indexed: 11/22/2022]
Abstract
One of the most notable trends in human evolution is the dramatic increase in brain size that has occurred in the great ape clade, culminating in humans. Of particular interest is the vast expanse of the cerebral cortex, which is believed to have resulted in our ability to perform higher cognitive functions. Recent investigations of congenital microcephaly in humans have resulted in the identification of several genes that non-redundantly and specifically influence mammalian brain size. These genes appear to affect neural progenitor cell number through microtubular organisation at the centrosome.
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Affiliation(s)
- Jacquelyn Bond
- Molecular Medicine Unit, University of Leeds, Clinical Sciences Building, St James's University Hospital, Beckett St., Leeds, West Yorkshire, LS9 7TF, UK.
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Huang SC, Liu ES, Chan SH, Munagala ID, Cho HT, Jagadeeswaran R, Benz EJ. Mitotic regulation of protein 4.1R involves phosphorylation by cdc2 kinase. Mol Biol Cell 2004; 16:117-27. [PMID: 15525677 PMCID: PMC539157 DOI: 10.1091/mbc.e04-05-0426] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The nonerythrocyte isoform of the cytoskeletal protein 4.1R (4.1R) is associated with morphologically dynamic structures during cell division and has been implicated in mitotic spindle function. In this study, we define important 4.1R isoforms expressed in interphase and mitotic cells by RT-PCR and mini-cDNA library construction. Moreover, we show that 4.1R is phosphorylated by p34cdc2 kinase on residues Thr60 and Ser679 in a mitosis-specific manner. Phosphorylated 4.1R135 isoform(s) associate with tubulin and Nuclear Mitotic Apparatus protein (NuMA) in intact HeLa cells in vivo as well as with the microtubule-associated proteins in mitotic asters assembled in vitro. Recombinant 4.1R135 is readily phosphorylated in mitotic extracts and reconstitutes mitotic aster assemblies in 4.1R-immunodepleted extracts in vitro. Furthermore, phosphorylation of these residues appears to be essential for the targeting of 4.1R to the spindle poles and for mitotic microtubule aster assembly in vitro. Phosphorylation of 4.1R also enhances its association with NuMA and tubulin. Finally, we used siRNA inhibition to deplete 4.1R from HeLa cells and provide the first direct genetic evidence that 4.1R is required to efficiently focus mitotic spindle poles. Thus, we suggest that 4.1R is a member of the suite of direct cdc2 substrates that are required for the establishment of a bipolar spindle.
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Affiliation(s)
- Shu-Ching Huang
- Department of Medical Oncology, Dana Farber Cancer Institute, Boston, MA 02115, USA.
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