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Srivastava Y, Donta M, Mireles LL, Paulucci-Holthauzen A, Shi L, Bedford MT, Waxham MN, McCrea PD. Exploring the PDZ, DUF, and LIM Domains of Pdlim5 in Dendrite Branching. Int J Mol Sci 2024; 25:8326. [PMID: 39125895 PMCID: PMC11312917 DOI: 10.3390/ijms25158326] [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: 05/18/2024] [Revised: 07/10/2024] [Accepted: 07/25/2024] [Indexed: 08/12/2024] Open
Abstract
The branched architecture of neuronal dendrites is a key factor in how neurons form ordered networks and discoveries continue to be made identifying proteins and protein-protein interactions that direct or execute the branching and extension of dendrites. Our prior work showed that the molecular scaffold Pdlim5 and delta-catenin, in conjunction, are two proteins that help regulate the branching and elongation of dendrites in cultured hippocampal neurons and do so through a phosphorylation-dependent mechanism triggered by upstream glutamate signaling. In this report we have focused on Pdlim5's multiple scaffolding domains and how each contributes to dendrite branching. The three identified regions within Pdlim5 are the PDZ, DUF, and a trio of LIM domains; however, unresolved is the intra-molecular conformation of Pdlim5 as well as which domains are essential to regulate dendritic branching. We address Pdlim5's structure and function by examining the role of each of the domains individually and using deletion mutants in the context of the full-length protein. Results using primary hippocampal neurons reveal that the Pdlim5 DUF domain plays a dominant role in increasing dendritic branching. Neither the PDZ domain nor the LIM domains alone support increased branching. The central role of the DUF domain was confirmed using deletion mutants in the context of full-length Pdlim5. Guided by molecular modeling, additional domain mapping studies showed that the C-terminal LIM domain forms a stable interaction with the N-terminal PDZ domain, and we identified key amino acid residues at the interface of each domain that are needed for this interaction. We posit that the central DUF domain of Pdlim5 may be subject to modulation in the context of the full-length protein by the intra-molecular interaction between the N-terminal PDZ and C-terminal LIM domains. Overall, our studies reveal a novel mechanism for the regulation of Pdlim5's function in the regulation of neuronal branching and highlight the critical role of the DUF domain in mediating these effects.
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Affiliation(s)
- Yogesh Srivastava
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Maxsam Donta
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Program in Genetics & Epigenetics, University of Texas MD Anderson Cancer Center, UT Health GSBS, Houston, TX 77030, USA
| | - Lydia L. Mireles
- Department of Neurobiology & Anatomy, University of Texas MD Anderson Cancer Center, UT Health GSBS, Houston, TX 77030, USA
| | | | - Leilei Shi
- Department of Epigenetics & Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Mark T. Bedford
- Program in Genetics & Epigenetics, University of Texas MD Anderson Cancer Center, UT Health GSBS, Houston, TX 77030, USA
- Department of Epigenetics & Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - M. Neal Waxham
- Department of Neurobiology & Anatomy, University of Texas MD Anderson Cancer Center, UT Health GSBS, Houston, TX 77030, USA
- Program in Neuroscience, University of Texas MD Anderson Cancer Center, UT Health GSBS, Houston, TX 77030, USA
| | - Pierre D. McCrea
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Program in Genetics & Epigenetics, University of Texas MD Anderson Cancer Center, UT Health GSBS, Houston, TX 77030, USA
- Program in Neuroscience, University of Texas MD Anderson Cancer Center, UT Health GSBS, Houston, TX 77030, USA
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Healy MD, Collins BM. The PDLIM family of actin-associated proteins and their emerging role in membrane trafficking. Biochem Soc Trans 2023; 51:2005-2016. [PMID: 38095060 PMCID: PMC10754285 DOI: 10.1042/bst20220804] [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] [Received: 09/29/2023] [Revised: 11/29/2023] [Accepted: 12/04/2023] [Indexed: 12/21/2023]
Abstract
The PDZ and LIM domain (PDLIM) proteins are associated with the actin cytoskeleton and have conserved in roles in metazoan actin organisation and function. They primarily function as scaffolds linking various proteins to actin and its binding partner α-actinin via two conserved domains; an N-terminal postsynaptic density 95, discs large and zonula occludens-1 (PDZ) domain, and either single or multiple C-terminal LIN-11, Isl-1 and MEC-3 (LIM) domains in the actinin-associated LIM protein (ALP)- and Enigma-related proteins, respectively. While their role in actin organisation, such as in stress fibres or in the Z-disc of muscle fibres is well known, emerging evidence also suggests a role in actin-dependent membrane trafficking in the endosomal system. This is mediated by a recently identified interaction with the sorting nexin 17 (SNX17) protein, an adaptor for the trafficking complex Commander which is itself intimately linked to actin-directed formation of endosomal recycling domains. In this review we focus on the currently understood structural basis for PDLIM function. The PDZ domains mediate direct binding to distinct classes of PDZ-binding motifs (PDZbms), including α-actinin and other actin-associated proteins, and a highly specific interaction with the type III PDZbm such as the one found in the C-terminus of SNX17. The structures of the LIM domains are less well characterised and how they engage with their ligands is completely unknown. Despite the lack of experimental structural data, we find that recently developed machine learning-based structure prediction methods provide insights into their potential interactions and provide a template for further studies of their molecular functions.
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Affiliation(s)
- Michael D. Healy
- The University of Queensland, Institute for Molecular Bioscience, St Lucia, Queensland 4072, Australia
| | - Brett M. Collins
- The University of Queensland, Institute for Molecular Bioscience, St Lucia, Queensland 4072, Australia
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Rood K, Yamauchi CR, Sharma U, Laxa RT, Robins C, Lanza G, Sánchez-Ruiz K, Khan A, Kim HS, Shields A, Kennedy K, Mirshahidi S, Perez MC, Firek A, Munir I, Simental AA, Khan S. Regulatory and Interacting Partners of PDLIM7 in Thyroid Cancer. Curr Oncol 2023; 30:10450-10462. [PMID: 38132395 PMCID: PMC10742985 DOI: 10.3390/curroncol30120761] [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: 09/05/2023] [Revised: 11/27/2023] [Accepted: 12/08/2023] [Indexed: 12/23/2023] Open
Abstract
Enigma protein, encoded by the PDLIM7 gene, is overexpressed in thyroid cancer in a stage-dependent manner, suggesting a potential involvement in the initiation and progression of thyroid cancer. The Enigma interacts with several cellular pathways, including PI3K/AKT, MDM2, and BMP-1. The Enigma is regulated by microRNAs. Specifically, we showed that the Enigma protein upregulation corresponds to the downregulation of Let-7 family genes. There is limited research on the interactions and regulation of the Enigma with other proteins/genes in thyroid cancer tissues, indicating a gap in current knowledge. Our aim is to establish the Enigma as a biomarker. We also aim to study the interacting partners of the Enigma signaling pathways and their probable miRNA regulation in thyroid cancer progression. Using Western blotting, densitometric analysis, immunoprecipitation (IP), and reverse IP, we detected the protein expression and protein-protein interactions in the corresponding papillary thyroid carcinomas (PTCs). Utilizing real-time qPCR assay and Pearson's correlation test, we highlighted the correlation between PDLIM7 and Let-7g gene expression in the same tissues. The results showed the differential upregulations of the Enigma protein in different stages of PTCs compared to benign tissues along with AKT, VDR, BMP-1, and MDM2 proteins. Loss of DBP was observed in a subset of PTCs. Strong interactions of the Enigma with PI3K/AKT and MDM2 were noted, along with a weaker BMP-1 interaction. Pearson's correlation coefficient analysis between PDLIM7 and let-7g gene expression was significant (p < 0.05); however, there was a weak inverse correlation (r = -0.27). The study suggests the potential utility of the PDLIM7-qPCR assay as a biomarker for thyroid cancer. The Enigma's interactions with key signaling pathways may provide valuable insights into the development of thyroid cancer. The study contributes to understanding the molecular mechanisms involving the Enigma protein in thyroid cancer and highlights its potential as a biomarker.
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Affiliation(s)
- Kristiana Rood
- Division of Biochemistry, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA; (K.R.); (C.R.Y.); (R.T.L.); (C.R.); (G.L.); (K.S.-R.); (A.K.); (H.S.K.)
- Division of Otolaryngology, Loma Linda University Health, Loma Linda, CA 92354, USA; (K.K.); (M.C.P.); (A.A.S.)
- Center for Health Disparities & Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Celina Romi Yamauchi
- Division of Biochemistry, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA; (K.R.); (C.R.Y.); (R.T.L.); (C.R.); (G.L.); (K.S.-R.); (A.K.); (H.S.K.)
- Division of Otolaryngology, Loma Linda University Health, Loma Linda, CA 92354, USA; (K.K.); (M.C.P.); (A.A.S.)
- Center for Health Disparities & Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Umang Sharma
- School of Public Health, Loma Linda University, Loma Linda, CA 92354, USA;
| | - Ria T. Laxa
- Division of Biochemistry, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA; (K.R.); (C.R.Y.); (R.T.L.); (C.R.); (G.L.); (K.S.-R.); (A.K.); (H.S.K.)
- Division of Otolaryngology, Loma Linda University Health, Loma Linda, CA 92354, USA; (K.K.); (M.C.P.); (A.A.S.)
- Center for Health Disparities & Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Collin Robins
- Division of Biochemistry, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA; (K.R.); (C.R.Y.); (R.T.L.); (C.R.); (G.L.); (K.S.-R.); (A.K.); (H.S.K.)
- Division of Otolaryngology, Loma Linda University Health, Loma Linda, CA 92354, USA; (K.K.); (M.C.P.); (A.A.S.)
- Center for Health Disparities & Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Gerardo Lanza
- Division of Biochemistry, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA; (K.R.); (C.R.Y.); (R.T.L.); (C.R.); (G.L.); (K.S.-R.); (A.K.); (H.S.K.)
- Division of Otolaryngology, Loma Linda University Health, Loma Linda, CA 92354, USA; (K.K.); (M.C.P.); (A.A.S.)
- Center for Health Disparities & Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Kidianys Sánchez-Ruiz
- Division of Biochemistry, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA; (K.R.); (C.R.Y.); (R.T.L.); (C.R.); (G.L.); (K.S.-R.); (A.K.); (H.S.K.)
- Division of Otolaryngology, Loma Linda University Health, Loma Linda, CA 92354, USA; (K.K.); (M.C.P.); (A.A.S.)
- Center for Health Disparities & Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Aminah Khan
- Division of Biochemistry, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA; (K.R.); (C.R.Y.); (R.T.L.); (C.R.); (G.L.); (K.S.-R.); (A.K.); (H.S.K.)
- Division of Otolaryngology, Loma Linda University Health, Loma Linda, CA 92354, USA; (K.K.); (M.C.P.); (A.A.S.)
- Center for Health Disparities & Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Hae Soo Kim
- Division of Biochemistry, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA; (K.R.); (C.R.Y.); (R.T.L.); (C.R.); (G.L.); (K.S.-R.); (A.K.); (H.S.K.)
- Division of Otolaryngology, Loma Linda University Health, Loma Linda, CA 92354, USA; (K.K.); (M.C.P.); (A.A.S.)
- Center for Health Disparities & Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Andrea Shields
- Department of Pathology & Human Anatomy, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA;
| | - Kari Kennedy
- Division of Otolaryngology, Loma Linda University Health, Loma Linda, CA 92354, USA; (K.K.); (M.C.P.); (A.A.S.)
| | | | - Mia C. Perez
- Division of Otolaryngology, Loma Linda University Health, Loma Linda, CA 92354, USA; (K.K.); (M.C.P.); (A.A.S.)
- Department of Pathology & Human Anatomy, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA;
| | - Anthony Firek
- Comparative Effectiveness and Clinical Outcomes Research Center (CECORC), Riverside University Health System, 26520 Cactus Ave, Moreno Valley, CA 92555, USA;
- Department of Endocrinology, Riverside University Health System, 26520 Cactus Ave, Moreno Valley, CA 92555, USA;
| | - Iqbal Munir
- Department of Endocrinology, Riverside University Health System, 26520 Cactus Ave, Moreno Valley, CA 92555, USA;
| | - Alfred A. Simental
- Division of Otolaryngology, Loma Linda University Health, Loma Linda, CA 92354, USA; (K.K.); (M.C.P.); (A.A.S.)
| | - Salma Khan
- Division of Biochemistry, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA; (K.R.); (C.R.Y.); (R.T.L.); (C.R.); (G.L.); (K.S.-R.); (A.K.); (H.S.K.)
- Division of Otolaryngology, Loma Linda University Health, Loma Linda, CA 92354, USA; (K.K.); (M.C.P.); (A.A.S.)
- Center for Health Disparities & Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
- Department of Internal Medicine, Loma Linda University School of Medicine, 11085 Campus St, Loma Linda, CA 92350, USA
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Structural and functional analysis of LIM domain-dependent recruitment of paxillin to αvβ3 integrin-positive focal adhesions. Commun Biol 2021; 4:380. [PMID: 33782527 PMCID: PMC8007706 DOI: 10.1038/s42003-021-01886-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Accepted: 02/11/2021] [Indexed: 02/06/2023] Open
Abstract
The LIM domain-dependent localization of the adapter protein paxillin to β3 integrin-positive focal adhesions (FAs) is not mechanistically understood. Here, by combining molecular biology, photoactivation and FA-isolation experiments, we demonstrate specific contributions of each LIM domain of paxillin and reveal multiple paxillin interactions in adhesion-complexes. Mutation of β3 integrin at a putative paxillin binding site (β3VE/YA) leads to rapidly inward-sliding FAs, correlating with actin retrograde flow and enhanced paxillin dissociation kinetics. Induced mechanical coupling of paxillin to β3VE/YA integrin arrests the FA-sliding, thereby disclosing an essential structural function of paxillin for the maturation of β3 integrin/talin clusters. Moreover, bimolecular fluorescence complementation unveils the spatial orientation of the paxillin LIM-array, juxtaposing the positive LIM4 to the plasma membrane and the β3 integrin-tail, while in vitro binding assays point to LIM1 and/or LIM2 interaction with talin-head domain. These data provide structural insights into the molecular organization of β3 integrin-FAs.
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Bioinformatic Analysis of Structure and Function of LIM Domains of Human Zyxin Family Proteins. Int J Mol Sci 2021; 22:ijms22052647. [PMID: 33808029 PMCID: PMC7961639 DOI: 10.3390/ijms22052647] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 02/26/2021] [Accepted: 03/01/2021] [Indexed: 02/07/2023] Open
Abstract
Members of the human Zyxin family are LIM domain-containing proteins that perform critical cellular functions and are indispensable for cellular integrity. Despite their importance, not much is known about their structure, functions, interactions and dynamics. To provide insights into these, we used a set of in-silico tools and databases and analyzed their amino acid sequence, phylogeny, post-translational modifications, structure-dynamics, molecular interactions, and functions. Our analysis revealed that zyxin members are ohnologs. Presence of a conserved nuclear export signal composed of LxxLxL/LxxxLxL consensus sequence, as well as a possible nuclear localization signal, suggesting that Zyxin family members may have nuclear and cytoplasmic roles. The molecular modeling and structural analysis indicated that Zyxin family LIM domains share similarities with transcriptional regulators and have positively charged electrostatic patches, which may indicate that they have previously unanticipated nucleic acid binding properties. Intrinsic dynamics analysis of Lim domains suggest that only Lim1 has similar internal dynamics properties, unlike Lim2/3. Furthermore, we analyzed protein expression and mutational frequency in various malignancies, as well as mapped protein-protein interaction networks they are involved in. Overall, our comprehensive bioinformatic analysis suggests that these proteins may play important roles in mediating protein-protein and protein-nucleic acid interactions.
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Firek AA, Perez MC, Gonda A, Lei L, Munir I, Simental AA, Carr FE, Becerra BJ, De Leon M, Khan S. Pathologic significance of a novel oncoprotein in thyroid cancer progression. Head Neck 2017; 39:2459-2469. [PMID: 29024261 DOI: 10.1002/hed.24913] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 05/17/2017] [Accepted: 07/12/2017] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND The incidence of thyroid cancer is increasing worldwide, and there is an emerging need to develop accurate tools for diagnosis. Fine needle aspiration biopsy has greatly improved evaluation of thyroid nodules, but challenges with indeterminate lesions remain in up to 25% of biopsies. Novel tissue biomarkers may assist in improved nodule characterization. Microcalcifications occurring in thyroid cancers suggest proteins involved in bone formation may play a role in thyroid carcinogenesis. We evaluated the expression of the known osteogenic protein, Enigma, in thyroid cancer as a candidate oncoprotein and role in carcinogenesis based on association with other known oncoproteins such as bone morphogenetic protein-1 (BMP-1). METHODS The expression of both Enigma and BMP-1 were evaluated by immunohistochemistry (IHC) in an equal number of benign (n = 120) and different histological subtypes of malignant (n = 120) human archival thyroid nodules with and without calcification. The colocalization of Enigma with BMP-1 was evaluated by confocal microscopy using the BZ analyzer. RESULTS Enigma was strongly expressed in thyroid cancer tissue with a higher immunoreactive score in advanced thyroid cancer compared to less advanced and benign nodules. Enigma was localized either in cytoplasm or nucleus depending on the histological subtypes. Higher expression of Enigma was associated with the tumor size and lymph node involvement. There was clear and strong colocalization signal of Enigma and that of BMP-1. Expression of Enigma occurred without regard to calcification in cancer tissue. CONCLUSION Enigma may serve as an oncoprotein marker, identifying benign from malignant thyroid tissue on FNA. Enigma may have a role in carcinogenesis of thyroid cancer independent of tissue calcification, possibly in relation to interaction with BMP-1.
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Affiliation(s)
- Anthony A Firek
- Division of Endocrinology and Metabolism, Riverside University Health System (RUHS), Moreno Valley, California.,Division of Biochemistry, Loma Linda University Health, Loma Linda, California
| | - Mia C Perez
- Department of Pathology and Human Anatomy, Loma Linda University School of Medicine, Loma Linda, California.,Division of Head and Neck Surgery, Department of Otolaryngology, Loma Linda University School of Medicine, Loma Linda, California
| | - Amber Gonda
- Department of Pathology and Human Anatomy, Loma Linda University School of Medicine, Loma Linda, California.,Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, California
| | - Li Lei
- Department of Pathology and Human Anatomy, Loma Linda University School of Medicine, Loma Linda, California
| | - Iqbal Munir
- Division of Endocrinology and Metabolism, Riverside University Health System (RUHS), Moreno Valley, California
| | - Alfred A Simental
- Division of Head and Neck Surgery, Department of Otolaryngology, Loma Linda University School of Medicine, Loma Linda, California
| | - Frances E Carr
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, Vermont
| | - Benjamin J Becerra
- School of Allied Health Professionals, Loma Linda University, Loma Linda, California
| | - Marino De Leon
- Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, California
| | - Salma Khan
- Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, California.,Division of Head and Neck Surgery, Department of Otolaryngology, Loma Linda University School of Medicine, Loma Linda, California.,Division of Biochemistry, Loma Linda University Health, Loma Linda, California.,Department of Internal Medicine, Loma Linda University Health, Loma Linda, California
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Sun H. Identification of key genes associated with gastric cancer based on DNA microarray data. Oncol Lett 2015; 11:525-530. [PMID: 26870242 PMCID: PMC4727153 DOI: 10.3892/ol.2015.3929] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 09/09/2015] [Indexed: 12/19/2022] Open
Abstract
The present study aimed to identify genes with a differential pattern of expression in gastric cancer (GC), and to find novel molecular biomarkers for GC diagnosis and therapeutic treatment. The gene expression profile of GSE19826, including 12 GC samples and 15 normal controls, was downloaded from the Gene Expression Omnibus database. Differentially-expressed genes (DEGs) were screened in the GC samples compared with the normal controls. Two-way hierarchical clustering of DEGs was performed to distinguish the normal controls from the GC samples. The co-expression coefficient was analyzed among the DEGs using the data from COXPRESdb. The gene co-expression network was constructed based on the DEGs using Cytoscape software, and modules in the network were analyzed by ClusterOne and Bingo. Furthermore, enrichment analysis of the DEGs in the modules was performed using the Database for Annotation, Visualization and Integrated Discovery. In total, 596 DEGs in the GC samples and 57 co-expression gene pairs were identified. A total of 7 genes were enriched in the same module, for which the function was phosphate transport and which was annotated to participate in the extracellular matrix-receptor interaction pathway. These genes were collagen, type VI, α3 (COL6A3), COL1A2, COL1A1, COL5A2, thrombospondin 2, COL11A1 and COL5A1. Overall, the present study identified several biomarkers for GC using the gene expression profiling of human GC samples. The COL family is a promising prognostic marker for GC. Gene expression products represent candidate biomarkers endowed with great potential for the early screening and therapy of GC patients.
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Affiliation(s)
- Hui Sun
- Department of Surgical Oncology, Weifang People's Hospital, Weifang, Shandong 261041, P.R. China
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Kales SC, Nau MM, Merchant AS, Lipkowitz S. Enigma prevents Cbl-c-mediated ubiquitination and degradation of RETMEN2A. PLoS One 2014; 9:e87116. [PMID: 24466333 PMCID: PMC3900716 DOI: 10.1371/journal.pone.0087116] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 12/23/2013] [Indexed: 12/24/2022] Open
Abstract
The Cbl proteins (Cbl, Cbl-b, and Cbl-c) are a highly conserved family of RING finger ubiquitin ligases (E3s) that function as negative regulators of tyrosine kinases in a wide variety of signal transduction pathways. In this study, we identify a new Cbl-c interacting protein, Enigma (PDLIM7). This interaction is specific to Cbl-c as Enigma fails to bind either of its closely related homologues, Cbl and Cbl-b. The binding between Enigma and Cbl-c is mediated through the LIM domains of Enigma as removal of all three LIM domains abrogates this interaction, while only LIM1 is sufficient for binding. Here we show that Cbl-c binds wild-type and MEN2A isoforms of the receptor tyrosine kinase, RET, and that Cbl-c enhances ubiquitination and degradation of activated RET. Enigma blocks Cbl-c-mediated RETMEN2A ubiquitination and degradation. Cbl-c decreased downstream ERK activation by RETMEN2A and co-expression of Enigma blocked the Cbl-c-mediated decrease in ERK activation. Enigma showed no detectable effect on Cbl-c-mediated ubiquitination of activated EGFR suggesting that this effect is specific to RET. Through mapping studies, we show that Cbl-c and Enigma bind RETMEN2A at different residues. However, binding of Enigma to RETMENA prevents Cbl-c recruitment to RETMEN2A. Consistent with these biochemical data, exploratory analyses of breast cancer patients with high expression of RET suggest that high expression of Cbl-c correlates with a good outcome, and high expression of Enigma correlates with a poor outcome. Together, these data demonstrate that Cbl-c can ubiquitinate and downregulate RETMEN2A and implicate Enigma as a positive regulator of RETMEN2A through blocking of Cbl-mediated ubiquitination and degradation.
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Affiliation(s)
- Stephen C. Kales
- Women’s Malignancies Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Marion M. Nau
- Women’s Malignancies Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Anand S. Merchant
- Center for Cancer Research Bioinformatics Core, Advanced Biomedical Computing Center, SAIC-Frederick, Frederick, Maryland, United States of America
| | - Stanley Lipkowitz
- Women’s Malignancies Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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de Vareilles M, Conceição LEC, Gómez-Requeni P, Kousoulaki K, Richard N, Rodrigues PM, Fladmark KE, Rønnestad I. Dietary lysine imbalance affects muscle proteome in zebrafish (Danio rerio): a comparative 2D-DIGE study. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2012; 14:643-654. [PMID: 22580902 DOI: 10.1007/s10126-012-9462-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 04/28/2012] [Indexed: 05/31/2023]
Abstract
Lysine (Lys) is an indispensable amino acid (AA) and generally the first limiting AA in vegetable protein sources in fish feeds. Inadequate dietary Lys availability may limit protein synthesis, accretion and growth of fish. This experiment aimed to further elucidate the role of Lys imbalance on growth by examining the myotomal muscle proteome of juvenile zebrafish (Danio rerio). Quadruplicate groups of 8 fish were fed either a low-Lys [Lys(-), 1.34 g kg(-1)], medium/control (Lys, 2.47 g kg(-1)) or high-Lys [Lys(+), 4.63 g kg(-1)] diet. Fish growth was monitored from 33 to 49 days post-fertilization (dpf) and trunk myotomal muscle proteome of Lys(-) and Lys(+) treatments were screened by 2D-DIGE and MALDI ToF tandem mass spectrometry. Growth rate was negatively affected by diet Lys(-). Out of 527 ± 11 (mean ± S.E.M.) protein spots detected (∼10-150 kDa and 4-7 pI value), 30 were over-expressed and 22 under-expressed in Lys(-) fish (|fold-change| >1.2, p value <0.05). Higher myosin light chains abundance and other myofibrillar proteins in Lys(-) fish pointed to increased sarcomeric degradation, indicating a higher protein turnover for supplying basal energy-saving metabolism rather than growth and muscle protein accretion. The Lys deficiency also possibly induced a higher feeding activity, reflected in the over-expression of beta enolase and mitochondrial ATP synthase. Contrarily, in the faster growing fish [Lys(+)], over-expression of apolipoprotein A-I, F-actin capping protein and Pdlim7 point to increased energy storage as fat and enhanced muscle growth, particularly by mosaic hyperplasia. Thus using an exploratory approach, this study pinpoints interesting candidates for further elucidating the role of dietary Lys on growth of juvenile fish.
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STAGSTED JAN. Journey beyond immunology. Regulation of receptor internalization by major histocompatibility complex class I (MHC-I) and effect of peptides derived from MHC-I. APMIS 2011. [DOI: 10.1111/j.1600-0463.1998.tb05657.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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11
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Sharma P, Shathasivam T, Ignatchenko V, Kislinger T, Gramolini AO. Identification of an FHL1 protein complex containing ACTN1, ACTN4, and PDLIM1 using affinity purifications and MS-based protein-protein interaction analysis. MOLECULAR BIOSYSTEMS 2011; 7:1185-96. [PMID: 21246116 DOI: 10.1039/c0mb00235f] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
INTRODUCTION Four and a half LIM domains protein 1 (FHL1) is the most widely expressed member of the FHL family of proteins, consisting of four and a half highly conserved LIM domains. A multifunctional and integral role for FHL1 has been implicated in muscle development, structural maintenance, and signaling. To date, 27 FHL1 mutations have been identified that result in at least six different X-linked myopathies, with patients often presenting with cardiovascular complications. Since proteins assemble into dynamic complexes within the cell, FHL1 likely mediates its biological functions in conjunction with other proteins. Delineation of FHL1 interactions could provide insight into its regulatory functions. METHODS We performed tandem affinity purification from human embryonic kidney 293 (HEK-293) cells to purify FHL1 and interacting proteins. To identify the potential interactors of FHL1 we performed a total of 9 different purifications from HEK-293 cells which included 3 experimental replicates for each biological condition: FHL1, tag control (DPYSL3), and negative control (empty vector). Purified samples were analyzed by liquid chromatography mass spectrometry (LC-MS). Potential interactors were then verified by immunoprecipitation from mouse heart ventricles and interactions visualized in adult cardiomyocytes using 3D fluorescence microscopy. RESULTS We identified a total of 310 different proteins from all 9 purifications and by applying stringent filtering criteria we eliminated all proteins found in any of the controls and only allowed those that were detected in two or more bait purification. We identified 34 high confidence potential binding partners of FHL1. We then showed that FHL1 exists as part of a complex that binds with PDLIM1, GSN and ACTN1.
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Affiliation(s)
- Parveen Sharma
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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12
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Jung CR, Lim JH, Choi Y, Kim DG, Kang KJ, Noh SM, Im DS. Enigma negatively regulates p53 through MDM2 and promotes tumor cell survival in mice. J Clin Invest 2010; 120:4493-506. [PMID: 21060154 DOI: 10.1172/jci42674] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 09/22/2010] [Indexed: 12/29/2022] Open
Abstract
The human E3 ubiquitin ligase murine double minute 2 (MDM2) targets the tumor suppressor p53 for ubiquitination and degradation but also promotes its own ubiquitination and subsequent degradation. As the balance between MDM2 and p53 levels plays a crucial role in regulating cell proliferation and apoptosis, we sought to identify factors selectively inhibiting MDM2 self-ubiquitination. Here we have shown that the LIM domain protein Enigma directly interacts with MDM2 to form a ternary complex with p53 in vitro and in human hepatoma and colon carcinoma cell lines and mouse embryonic fibroblasts. We found that Enigma elicited p53 degradation by inhibiting MDM2 self-ubiquitination and increasing its ubiquitin ligase activity toward p53 in cells. Moreover, mitogenic stimuli such as serum, FGF, and HGF increased Enigma transcription via induction of serum response factor (SRF), leading to MDM2 stabilization and subsequent p53 degradation. We observed similar results in the livers of mice treated with HGF. In humans, we found SRF and Enigma coexpressed with MDM2 but not p53 in several liver and stomach tumors. Finally, we showed that Enigma promoted cell survival and chemoresistance by suppressing p53-mediated apoptosis in both cell lines and a mouse xenograft model. Our findings suggest a role for Enigma in tumorigenesis and uncover a mechanism whereby mitogens attenuate p53 antiproliferative activity through an SRF/Enigma/MDM2 pathway.
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Affiliation(s)
- Cho-Rok Jung
- Gene Therapy Research Unit, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea
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Krcmery J, Camarata T, Kulisz A, Simon HG. Nucleocytoplasmic functions of the PDZ-LIM protein family: new insights into organ development. Bioessays 2010; 32:100-8. [PMID: 20091751 DOI: 10.1002/bies.200900148] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Recent work on the PDZ-LIM protein family has revealed that it has important activities at the cellular level, mediating signals between the nucleus and the cytoskeleton, with significant impact on organ development. We review and integrate current knowledge about the PDZ-LIM protein family and propose a new functional role, sequestering nuclear factors in the cytoplasm. Characterized by their PDZ and LIM domains, the PDZ-LIM family is comprised of evolutionarily conserved proteins found throughout the animal kingdom, from worms to humans. Combining two functional domains in one protein, PDZ-LIM proteins have wide-ranging and multi-compartmental cell functions during development and homeostasis. In contrast, misregulation can lead to cancer formation and progression. New emerging roles include interactions with integrins, T-box transcription factors, and receptor tyrosine kinases. Facilitating the assembly of protein complexes, PDZ-LIM proteins can act as signal modulators, influence actin dynamics, regulate cell architecture, and control gene transcription.
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Affiliation(s)
- Jennifer Krcmery
- Department of Pediatrics, Northwestern University, The Feinberg School of Medicine, Children's Memorial Research Center, Chicago, IL 60614, USA
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14
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CLP36 interacts with palladin in dorsal root ganglion neurons. Neurosci Lett 2010; 476:53-7. [PMID: 20381583 DOI: 10.1016/j.neulet.2010.03.081] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2010] [Revised: 03/31/2010] [Accepted: 03/31/2010] [Indexed: 11/20/2022]
Abstract
CLP36, a member of the alpha-actinin-associated LIM protein (ALP)/enigma protein family, plays a role in neurite outgrowth in the peripheral nervous system. However, the underlying molecular mechanisms are not known. In this study, we performed yeast two-hybrid screening of an E18 mouse whole-body cDNA library with CLP36 as the bait and isolated palladin as a CLP36-binding protein. Palladin is an actin-binding protein and it was shown to have a role in the extension of cortical neurons. A coimmunoprecipitation study showed that CLP36 and palladin formed a complex in the dorsal root ganglion (DRG). In addition, CLP36 and palladin were colocalized in the neurites and cell bodies of primary DRG neurons. Furthermore, sciatic nerve transection increased the expression of both CLP36 and palladin mRNAs in DRG neurons, with the increase in CLP36 mRNA being more prominent. This implies that CLP36 has a more specific role in nerve regeneration than palladin. Our results suggest that CLP36 may interact with palladin to influence neurite outgrowth during sciatic nerve regeneration.
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Verhey van Wijk N, Witte F, Feike AC, Schambony A, Birchmeier W, Mundlos S, Stricker S. The LIM domain protein Wtip interacts with the receptor tyrosine kinase Ror2 and inhibits canonical Wnt signalling. Biochem Biophys Res Commun 2009; 390:211-6. [DOI: 10.1016/j.bbrc.2009.09.086] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Accepted: 09/22/2009] [Indexed: 11/24/2022]
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16
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Strohbach C, Kleinman S, Linkhart T, Amaar Y, Chen ST, Mohan S, Strong D. Potential involvement of the interaction between insulin-like growth factor binding protein (IGFBP)-6 and LIM mineralization protein (LMP)-1 in regulating osteoblast differentiation. J Cell Biochem 2008; 104:1890-905. [PMID: 18395833 DOI: 10.1002/jcb.21761] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Insulin-like growth factor binding protein (IGFBP)-6 has been reported to inhibit differentiation of myoblasts and osteoblasts. In the current study, we explored the mechanisms underlying IGFBP-6 effects on osteoblast differentiation. During MC3T3-E1 osteoblast differentiation, we found that IGFBP-6 protein was down-regulated. Overexpression of IGFBP-6 in MC3T3-E1 and human bone cells inhibited nodule formation, osteocalcin mRNA expression and ALP activity. Furthermore, accumulation of IGFBP-6 in the culture media was not required for any of these effects suggesting that IGFBP-6 suppressed osteoblast differentiation by an intracellular mechanism. A yeast two-hybrid screen of an osteosarcoma library was conducted to identify intracellular binding partners to account for IGFBP-6 inhibitory effects on osteoblast differentiation. LIM mineralizing protein (LMP-1) was identified as a high affinity IGFBP-6 binding partner. Physical interaction between IGFBP-6 and LMP-1 was confirmed by co-immunoprecipitation. Fluorescent protein fusion constructs for LMP-1 and IGFBP-6 were transiently transfected into osteoblasts to provide evidence of subcellular locations for each protein. Coexpression of LMP-1-GFP and IGFBP-6-RFP resulted in overlapping subcellular localization of LMP-1 and IGFBP-6. To determine if there was a functional association of IGFBP-6 and LMP-1 as well as a physical association, we studied the effect of IGFBP-6, LMP-1 and their combination on type I procollagen promoter activity. LMP-1 increased promoter activity while IGFBP-6 reduced promoter activity, and coexpression of LMP-1 with IGFBP-6 abrogated IGFBP-6 suppression. These studies provide evidence that overexpression of IGFBP-6 suppresses human and murine osteoblast differentiation, that IGFBP-6 and LMP-1 physically interact, and supports the conclusion that this interaction may be functionally relevant.
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Affiliation(s)
- Cassandra Strohbach
- Jerry L. Pettis Memorial VA Center, Musculoskeletal Disease Center, Loma Linda, CA 92357, USA
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Strohbach CA, Rundle CH, Wergedal JE, Chen ST, Linkhart TA, Lau KHW, Strong DD. LMP-1 retroviral gene therapy influences osteoblast differentiation and fracture repair: a preliminary study. Calcif Tissue Int 2008; 83:202-11. [PMID: 18709396 DOI: 10.1007/s00223-008-9163-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Accepted: 07/08/2008] [Indexed: 12/12/2022]
Abstract
LIM mineralization protein-1 (LMP-1) is a novel intracellular osteogenic factor associated with bone development that has been implicated in the bone morphogenetic protein (BMP) pathway. This preliminary study evaluated the possibility of LMP-1-based retroviral gene therapy to stimulate osteoblast differentiation in vitro and fracture repair in vivo. A Moloney leukemia virus (MLV)-based retroviral vector to express LMP-1 with a hemagglutinin (HA) tag was developed, and its effects were evaluated on MC3T3-E1 cell differentiation and in the rat femur fracture model. MC3T3-E1 osteoblasts transduced with the MLV-HA-LMP-1 vector demonstrated significantly increased osteoblast marker gene expression (P < 0.05) and mineral deposition compared to control transduced cells. Femoral midshaft fractures were produced in Fischer 344 rats by the three-point bending technique. The MLV-HA-LMP-1 or control vector was applied at the fracture site through percutaneous injections 1 day postfracture. Analysis of fracture healing of 10 MLV-HA-LMP-1-treated and 10 control MLV-beta-galactosidase (beta-gal)-treated animals was completed at 3 weeks by X-ray, peripheral quantitative computed tomography, and histology. MLV-HA-LMP-1-treated animals had 63% more bone mineral content at the fracture site (P < 0.01), 34% greater total hard callus area (P < 0.05), and 45% less cartilage in the fracture callus (P < 0.05) compared to MLV-beta-gal-treated animals. There was no effect of LMP-1 treatment on the density of the hard callus. Immunohistochemistry revealed expression of the LMP-1 transgene in the fracture callus at 21 days postfracture. Immunohistochemistry also revealed that LMP-1 transgene expression did not result in an increase in BMP-4 expression in the fracture callus. Compared to MLV-BMP-4 gene therapy studies, MLV-HA-LMP-1 gene therapy improved bony union of the fracture gap to a greater extent and did not cause heterotopic bone formation. This suggests that LMP-1 may be a better potential candidate for gene therapy for fracture repair than BMP-4. These exciting, albeit preliminary, findings indicate that LMP-1-based gene therapy may potentially be a simple and effective means to enhance fracture repair that warrants further investigation.
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Affiliation(s)
- Cassandra A Strohbach
- Musculoskeletal Disease Center, Jerry L. Pettis Memorial VA Medical Center, 11201 Benton Street, Loma Linda, CA 92357, USA
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A broken heart: a stretch too far: an overview of mouse models with mutations in stretch-sensor components. Int J Cardiol 2008; 131:33-44. [PMID: 18715658 DOI: 10.1016/j.ijcard.2008.06.049] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2007] [Revised: 05/07/2008] [Accepted: 06/03/2008] [Indexed: 12/11/2022]
Abstract
With every heartbeat the heart must contract and relax. This seemingly trivial process critically needs tight control of contraction and relaxation phases, and extremely efficient coordination between these two phases to control blood flow and maintain cardiac homeostasis. To achieve this, specialized sensors are required to detect the inherent repeatedly changing environment and needs. One sensor is a stretch-sensor that monitors the filling of the ventricles. Its molecular identity and localization are only partly understood. Here we give a synopsis of the genetic models that leap into our understanding of stretch-sensors. We focus on the widely acknowledged sarcomeric sensor at the Z-disc and the costamere sensor at the sarcolemma. Recently, several novel components of both sensors were discovered. Given that these two sensors seem physically connected, it is likely that these two models are not mutually exclusive and might even communicate. We describe briefly how candidate and known proteins within these sensors receive and transduce mechanical signals in the cardiomyocyte that lead to changes in gene expression underlying homeostasis and its restoration in the heart. Emphasis is placed on the putative link between altered stretch-sensor function and heart failure observed in different genetic mouse models of stretch-sensor components.
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Camarata T, Bimber B, Kulisz A, Chew TL, Yeung J, Simon HG. LMP4 regulates Tbx5 protein subcellular localization and activity. ACTA ACUST UNITED AC 2006; 174:339-48. [PMID: 16880269 PMCID: PMC2064230 DOI: 10.1083/jcb.200511109] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The limb- and heart-specific Tbx5 transcription factor coexpresses with and directly binds to the novel PDZ-LIM domain protein, LMP4. LMP4 is distributed in the cytoplasm associated with the actin cytoskeleton. In the presence of LMP4, Tbx5 shuttles dynamically between the nucleus and cytoplasm and, in a complex with LMP4, localizes to actin filaments. Nuclear and cytoplasmic Tbx5 distribution in developing chicken wings suggests the functional significance of the LMP4–Tbx5 interaction. In primary epicardial cells, we demonstrate that Tbx5 protein subcellular relocalization can be stimulated by external signals that induce cell differentiation. To test whether the relocalization from nuclear to cytoplasmic sites interferes with downstream gene expression, we used limb-specific Fgf10 and heart-specific Anf promoter-luciferase reporters and demonstrate that LMP4 acts as a repressor of Tbx5 activity. These studies reveal a previously unknown mechanism for Tbx transcription factor regulation in vertebrate limb and heart development and provide a better understanding of the molecular basis of hand/heart birth defects associated with Tbx5 mutations.
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Affiliation(s)
- Troy Camarata
- Department of Pediatrics, Children's Memorial Research Center, Feinberg School of Medicine, Northwestern University, Chicago, IL 60614, USA
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20
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Barrès R, Grémeaux T, Gual P, Gonzalez T, Gugenheim J, Tran A, Le Marchand-Brustel Y, Tanti JF. Enigma interacts with adaptor protein with PH and SH2 domains to control insulin-induced actin cytoskeleton remodeling and glucose transporter 4 translocation. Mol Endocrinol 2006; 20:2864-75. [PMID: 16803868 PMCID: PMC1892539 DOI: 10.1210/me.2005-0455] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
APS (adaptor protein with PH and SH2 domains) initiates a phosphatidylinositol 3-kinase-independent pathway involved in insulin-stimulated glucose transport. We recently identified Enigma, a PDZ and LIM domain-containing protein, as a partner of APS and showed that APS-Enigma complex plays a critical role in actin cytoskeleton organization in fibroblastic cells. Because actin rearrangement is important for insulin-induced glucose transporter 4 (Glut 4) translocation, we studied the potential involvement of Enigma in insulin-induced glucose transport in 3T3-L1 adipocytes. Enigma mRNA was expressed in differentiated adipocytes and APS and Enigma were colocalized with cortical actin. Expression of an APS mutant unable to bind Enigma increased the insulin-induced Glut 4 translocation to the plasma membrane. By contrast, overexpression of Enigma inhibited insulin-stimulated glucose transport and Glut 4 translocation without alterations in proximal insulin signaling. This inhibitory effect was prevented with the deletion of the LIM domains of Enigma. Using time-lapse fluorescent microscopy of green fluorescent protein-actin, we demonstrated that the overexpression of Enigma altered insulin-induced actin rearrangements, whereas the expression of Enigma without its LIM domains was without effect. A physiological link between increased expression of Enigma and an alteration in insulin-induced glucose uptake was suggested by the increase in Enigma mRNA expression in adipose tissue of diabetic obese patients. Taken together, these data strongly suggest that the interaction between APS and Enigma is involved in insulin-induced Glut 4 translocation by regulating cortical actin remodeling and raise the possibility that modification of APS/Enigma ratio could participate in the alteration of insulin-induced glucose uptake in adipose tissue.
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Affiliation(s)
- Romain Barrès
- Signalisation moléculaire et obésité
INSERM : U568 IFR50Université de Nice Sophia-AntipolisFaculte de Medecine
Avenue de Valombrose
06107 NICE CEDEX 2,FR
| | - Thierry Grémeaux
- Signalisation moléculaire et obésité
INSERM : U568 IFR50Université de Nice Sophia-AntipolisFaculte de Medecine
Avenue de Valombrose
06107 NICE CEDEX 2,FR
| | - Philippe Gual
- Signalisation moléculaire et obésité
INSERM : U568 IFR50Université de Nice Sophia-AntipolisFaculte de Medecine
Avenue de Valombrose
06107 NICE CEDEX 2,FR
| | - Teresa Gonzalez
- Signalisation moléculaire et obésité
INSERM : U568 IFR50Université de Nice Sophia-AntipolisFaculte de Medecine
Avenue de Valombrose
06107 NICE CEDEX 2,FR
| | - Jean Gugenheim
- Service de Chirurgie Digestive et Centre de Transplantation Hépatique
CHU de NICE06107 Nice,FR
| | - Albert Tran
- Fédération d'Hépatologie
CHU Nice06107 Nice,FR
| | - Yannick Le Marchand-Brustel
- Signalisation moléculaire et obésité
INSERM : U568 IFR50Université de Nice Sophia-AntipolisFaculte de Medecine
Avenue de Valombrose
06107 NICE CEDEX 2,FR
| | - Jean-François Tanti
- Signalisation moléculaire et obésité
INSERM : U568 IFR50Université de Nice Sophia-AntipolisFaculte de Medecine
Avenue de Valombrose
06107 NICE CEDEX 2,FR
- * Correspondence should be adressed to: Jean-François Tanti
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Chen Y, Lai M, Maeno-Hikichi Y, Zhang JF. Essential role of the LIM domain in the formation of the PKCɛ–ENH–N-type Ca2+ channel complex. Cell Signal 2006; 18:215-24. [PMID: 15979848 DOI: 10.1016/j.cellsig.2005.04.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Revised: 04/14/2005] [Accepted: 04/19/2005] [Indexed: 01/21/2023]
Abstract
A LIM domain is a specialized double-zinc finger motif found in a variety of proteins. LIM domains are thought to function as molecular modules, mediating specific protein-protein interactions in cellular signaling. In a recent study, we have demonstrated that ENH, which has three consecutive LIM domains, acts as an adaptor protein for the formation of a functional PKCepsilon-ENH-N-type Ca2+ channel complex in neurons. Formation of this complex selectively recruits PKCepsilon to its specific substrate, N-type Ca2+ channels, and is critical for rapid and efficient potentiation of the Ca2+ channel activity by PKC in neurons. However, it is not clear whether changes in the local Ca2+ concentrations near the channel mouth may affect the formation of the triprotein complex. Furthermore, the molecular determinants for the interactions among these three proteins remain unknown. Biochemical studies were performed to address these questions. Within the physiological Ca2+ concentration range (0-300 microM), binding of ENH to the channel C-terminus was significantly increased by Ca2+, whereas increased Ca2+ levels led to dissociation of PKCepsilon from ENH. Mutagenesis studies revealed that the second LIM domain in ENH was primarily responsible for Ca2+-dependent binding of ENH to both the Ca2+ channel C-terminus and PKCepsilon. ENH existed as a dimer in vivo. PKCepsilon translocation inhibition peptide, which blocks the translocation of PKCepsilon from the cytosol to the membrane, inhibited the interaction between PKCepsilon and ENH. These results provide a molecular mechanism for how the PKCepsilon-ENH-N-type Ca2+ channel complex is formed and regulated, as well as potential drug targets to selectively disrupt the PKC signaling complex.
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Affiliation(s)
- Yuan Chen
- Department of Physiology, Jefferson Medical College, 1020 Locust Street, Philadelphia, PA 19107, USA
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Frank D, Kuhn C, Katus HA, Frey N. The sarcomeric Z-disc: a nodal point in signalling and disease. J Mol Med (Berl) 2006; 84:446-68. [PMID: 16416311 DOI: 10.1007/s00109-005-0033-1] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2005] [Accepted: 11/23/2005] [Indexed: 12/11/2022]
Abstract
The perception of the Z-disc in striated muscle has undergone significant changes in the past decade. Traditionally, the Z-disc has been viewed as a passive constituent of the sarcomere, which is important only for the cross-linking of thin filaments and transmission of force generated by the myofilaments. The recent discovery of multiple novel molecular components, however, has shed light on an emerging role for the Z-disc in signal transduction in both cardiac and skeletal muscles. Strikingly, mutations in several Z-disc proteins have been shown to cause cardiomyopathies and/or muscular dystrophies. In addition, the elusive cardiac stretch receptor appears to localize to the Z-disc. Various signalling molecules have been shown to interact with Z-disc proteins, several of which shuttle between the Z-disc and other cellular compartments such as the nucleus, underlining the dynamic nature of Z-disc-dependent signalling. In this review, we provide a systematic view on the currently known Z-disc components and the functional significance of the Z-disc as an interface between biomechanical sensing and signalling in cardiac and skeletal muscle functions and diseases.
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Affiliation(s)
- Derk Frank
- Department of Internal Medicine III, University of Heidelberg, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
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Barrès R, Gonzalez T, Le Marchand-Brustel Y, Tanti JF. The interaction between the adaptor protein APS and Enigma is involved in actin organisation. Exp Cell Res 2005; 308:334-44. [PMID: 15946664 DOI: 10.1016/j.yexcr.2005.05.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2004] [Revised: 05/03/2005] [Accepted: 05/04/2005] [Indexed: 11/17/2022]
Abstract
APS (adaptor protein with PH and SH2 domains) is an adaptor protein phosphorylated by several tyrosine kinase receptors including the insulin receptor. To identify novel binding partners of APS, we performed yeast two-hybrid screening. We identified Enigma, a PDZ and LIM domain-containing protein that was previously shown to be associated with the actin cytoskeleton. In HEK 293 cells, Enigma interacted specifically with APS, but not with the APS-related protein SH2-B. This interaction required the NPTY motif of APS and the LIM domains of Enigma. In NIH-3T3 cells that express the insulin receptor, Enigma and APS were partially co-localised with F-actin in small ruffling structures. Insulin increased the complex formation between APS and Enigma and their co-localisation in large F-actin containing ruffles. While in NIH-3T3 and HeLa cells the co-expression of both Enigma and APS did not modify the actin cytoskeleton organisation, expression of Enigma alone led to the formation of F-actin clusters. Similar alteration in actin cytoskeleton organisation was observed in cells expressing both Enigma and APS with a mutation in the NPTY motif. These results identify Enigma as a novel APS-binding protein and suggest that the APS/Enigma complex plays a critical role in actin cytoskeleton organisation.
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Affiliation(s)
- Romain Barrès
- INSERM U568 and IFR 50, Faculté de Médecine, Avenue de Valombrose, 06107 Nice Cedex 02, France
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24
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Schulz TW, Nakagawa T, Licznerski P, Pawlak V, Kolleker A, Rozov A, Kim J, Dittgen T, Köhr G, Sheng M, Seeburg PH, Osten P. Actin/alpha-actinin-dependent transport of AMPA receptors in dendritic spines: role of the PDZ-LIM protein RIL. J Neurosci 2005; 24:8584-94. [PMID: 15456832 PMCID: PMC6729893 DOI: 10.1523/jneurosci.2100-04.2004] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The efficacy of excitatory transmission in the brain depends to a large extent on synaptic AMPA receptors, hence the importance of understanding the delivery and recycling of the receptors at the synaptic sites. Here we report a novel regulation of the AMPA receptor transport by a PDZ (postsynaptic density-95/Drosophila disc large tumor suppressor zona occludens 1) and LIM (Lin11/rat Isl-1/Mec3) domain-containing protein, RIL (reversion-induced LIM protein). We show that RIL binds to the AMPA glutamate receptor subunit GluR-A C-terminal peptide via its LIM domain and to alpha-actinin via its PDZ domain. RIL is enriched in the postsynaptic density fraction isolated from rat forebrain, strongly localizes to dendritic spines in cultured neurons, and coprecipitates, together with alpha-actinin, in a protein complex isolated by immunoprecipitation of AMPA receptors from forebrain synaptosomes. Functionally, in heterologous cells, RIL links AMPA receptors to the alpha-actinin/actin cytoskeleton, an effect that appears to apply selectively to the endosomal surface-internalized population of the receptors. In cultured neurons, an overexpression of recombinant RIL increases the accumulation of AMPA receptors in dendritic spines, both at the total level, as assessed by immunodetection of endogenous GluR-A-containing receptors, and at the synaptic surface, as assessed by recording of miniature EPSCs. Our results thus indicate that RIL directs the transport of GluR-A-containing AMPA receptors to and/or within dendritic spines, in an alpha-actinin/actin-dependent manner, and that such trafficking function promotes the synaptic accumulation of the receptors.
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Affiliation(s)
- Torsten W Schulz
- Max Planck Institute for Medical Research, Department of Molecular Neurobiology, 69120 Heidelberg, Germany
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Kadrmas JL, Beckerle MC. The LIM domain: from the cytoskeleton to the nucleus. Nat Rev Mol Cell Biol 2004; 5:920-31. [PMID: 15520811 DOI: 10.1038/nrm1499] [Citation(s) in RCA: 560] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
First described 15 years ago as a cysteine-rich sequence that was common to a small group of homeodomain transcription factors, the LIM domain is now recognized as a tandem zinc-finger structure that functions as a modular protein-binding interface. LIM domains are present in many proteins that have diverse cellular roles as regulators of gene expression, cytoarchitecture, cell adhesion, cell motility and signal transduction. An emerging theme is that LIM proteins might function as biosensors that mediate communication between the cytosolic and the nuclear compartments.
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Affiliation(s)
- Julie L Kadrmas
- Huntsman Cancer Institute and the Department of Biology, University of Utah, 2000 East, Circle of Hope, Salt Lake City, Utah 84112, USA
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Blagoev B, Ong SE, Kratchmarova I, Mann M. Temporal analysis of phosphotyrosine-dependent signaling networks by quantitative proteomics. Nat Biotechnol 2004; 22:1139-45. [PMID: 15314609 DOI: 10.1038/nbt1005] [Citation(s) in RCA: 526] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2004] [Accepted: 06/08/2004] [Indexed: 12/17/2022]
Abstract
To study the global dynamics of phosphotyrosine-based signaling events in early growth factor stimulation, we developed a mass spectrometric method that converts temporal changes to differences in peptide isotopic abundance. The proteomes of three cell populations were metabolically encoded with different stable isotopic forms of arginine. Each population was stimulated by epidermal growth factor for a different length of time, and tyrosine-phosphorylated proteins and closely associated binders were affinity purified. Arginine-containing peptides occurred in three forms, which were quantified; we then combined two experiments to generate five-point dynamic profiles. We identified 81 signaling proteins, including virtually all known epidermal growth factor receptor substrates, 31 novel effectors and the time course of their activation upon epidermal growth factor stimulation. Global activation profiles provide an informative perspective on cell signaling and will be crucial to modeling signaling networks in a systems biology approach.
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Vallenius T, Scharm B, Vesikansa A, Luukko K, Schäfer R, Mäkelä TP. The PDZ-LIM protein RIL modulates actin stress fiber turnover and enhances the association of alpha-actinin with F-actin. Exp Cell Res 2004; 293:117-28. [PMID: 14729062 DOI: 10.1016/j.yexcr.2003.09.004] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
ALP, CLP-36 and RIL form the ALP subfamily of PDZ-LIM proteins. ALP has been implicated in sarcomere function in muscle cells in association with alpha-actinin. The closely related CLP-36 is predominantly expressed in nonmuscle cells, where it localizes to actin stress fibers also in association with alpha-actinin. Here we have studied the expression and functions of RIL originally identified as a gene downregulated in H-ras-transformed cells. RIL was mostly expressed in nonmuscle epithelial cells with a pattern distinct from that of CLP-36. RIL protein was found to localize to actin stress fibers in nonmuscle cells similarly to CLP-36. However, RIL expression led to partially abnormal actin filaments showing thick irregular stress fibers not seen with CLP-36. Furthermore, live cell imaging demonstrated altered stress fiber dynamics with rapid formation of new fibers and frequent collapse of thick irregular fibers in EGFP-RIL-expressing cells. These effects may be mediated through the association of RIL with alpha-actinin, as RIL was found to associate with alpha-actinin via its PDZ domain, and RIL enhanced the ability of alpha-actinin to cosediment with actin filaments. These results implicate the RIL PDZ-LIM protein as a regulator of actin stress fiber turnover.
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Affiliation(s)
- Tea Vallenius
- Molecular Cancer Biology Program, Institute of Biomedicine and Helsinki University Central Hospital, University of Helsinki, Biomedicum Helsinki, Finland
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28
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Kiefer J, Alexander A, Farach-Carson MC. Type I collagen-mediated changes in gene expression and function of prostate cancer cells. Cancer Treat Res 2004; 118:101-24. [PMID: 15043190 DOI: 10.1007/978-1-4419-9129-4_5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In this study, cDNA microarrays were used to characterize gene expression changes elicited in prostate cancer cells by plating them on type I collagen. The results clearly reveal changes in the expression of genes associated with cellular signaling, cellular metabolism, gene transcription and gene translation which are indicative of cells that are actively proliferating. Together these results suggest that these changes in the gene expression profiles mediated by type I collagen may influence the proliferative capacity of prostate cancer cells in the bone microenvironment and facilitate development of prostate cancer bone metastases. Additionally, the microarray approach provides an invaluable tool to determine and track changes in gene expression in numerous disease states including prostate cancer. This technology is certain to facilitate discovery of new therapeutic gene targets.
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Affiliation(s)
- Jeffrey Kiefer
- Department of Biological Sciences, University of Delaware, USA
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29
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Velyvis A, Vaynberg J, Yang Y, Vinogradova O, Zhang Y, Wu C, Qin J. Structural and functional insights into PINCH LIM4 domain-mediated integrin signaling. Nat Struct Mol Biol 2003; 10:558-64. [PMID: 12794636 DOI: 10.1038/nsb938] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2003] [Accepted: 05/09/2003] [Indexed: 11/09/2022]
Abstract
PINCH is an adaptor protein found in focal adhesions, large cellular complexes that link extracellular matrix to the actin cytoskeleton. PINCH, which contains an array of five LIM domains, has been implicated as a platform for multiple protein-protein interactions that mediate integrin signaling within focal adhesions. We had previously characterized the LIM1 domain of PINCH, which functions in focal adhesions by binding specifically to integrin-linked kinase. Using NMR spectroscopy, we show here that the PINCH LIM4 domain, while maintaining the conserved LIM scaffold, recognizes the third SH3 domain of another adaptor protein, Nck2 (also called Nckbeta or Grb4), in a manner distinct from that of the LIM1 domain. Point mutation of LIM residues in the SH3-binding interface disrupted LIM-SH3 interaction and substantially impaired localization of PINCH to focal adhesions. These data provide novel structural insight into LIM domain-mediated protein-protein recognition and demonstrate that the PINCH-Nck2 interaction is an important component of the focal adhesion assembly during integrin signaling.
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Affiliation(s)
- Algirdas Velyvis
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10500 Euclid Avenue, Cleveland, Ohio 44102, USA
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Clark KA, McElhinny AS, Beckerle MC, Gregorio CC. Striated muscle cytoarchitecture: an intricate web of form and function. Annu Rev Cell Dev Biol 2003; 18:637-706. [PMID: 12142273 DOI: 10.1146/annurev.cellbio.18.012502.105840] [Citation(s) in RCA: 472] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Striated muscle is an intricate, efficient, and precise machine that contains complex interconnected cytoskeletal networks critical for its contractile activity. The individual units of the sarcomere, the basic contractile unit of myofibrils, include the thin, thick, titin, and nebulin filaments. These filament systems have been investigated intensely for some time, but the details of their functions, as well as how they are connected to other cytoskeletal elements, are just beginning to be elucidated. These investigations have advanced significantly in recent years through the identification of novel sarcomeric and sarcomeric-associated proteins and their subsequent functional analyses in model systems. Mutations in these cytoskeletal components account for a large percentage of human myopathies, and thus insight into the normal functions of these proteins has provided a much needed mechanistic understanding of these disorders. In this review, we highlight the components of striated muscle cytoarchitecture with respect to their interactions, dynamics, links to signaling pathways, and functions. The exciting conclusion is that the striated muscle cytoskeleton, an exquisitely tuned, dynamic molecular machine, is capable of responding to subtle changes in cellular physiology.
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Affiliation(s)
- Kathleen A Clark
- Department of Cell Biology, University of Arizona, Tucson 85724, USA
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31
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Früh K, Bartee E, Gouveia K, Mansouri M. Immune evasion by a novel family of viral PHD/LAP-finger proteins of gamma-2 herpesviruses and poxviruses. Virus Res 2002; 88:55-69. [PMID: 12297327 DOI: 10.1016/s0168-1702(02)00120-x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Many viruses have developed mechanisms to escape the cellular immune response by inhibiting antigen presentation from major histocompatibility complex (MHC) molecules. Most of these immune escape mechanisms are highly host adapted and specific to a given virus species or family. Recent observations however, suggest that a conserved family of viral proteins is used by both gamma-2 herpesviruses and by poxviruses to downregulate MHC class I. In addition, other cell surface molecules involved in immune recognition by T cells and NK cells are also downregulated. Two open reading frames (ORFs), K3 and K5, of Kaposi's sarcoma associated virus (KSHV) and one ORFs, K3, of murine gamma herpesvirus 68 (MHV 68) inhibit surface expression of MHC I molecules. In cells transfected with KSHV-K3 and KSHV-K5, MHC I is rapidly endocytosed and degraded in lysosomes whereas in MHV 68-K3 transfected cells, MHC I is targeted for proteasomal degradation. The K3 and K5 genes display a characteristic conserved domain structure of an amino-terminal plant homeo domain/leukemia associated protein-zinc finger domain followed by two carboxyterminal transmembrane domains. Related proteins are not only found in other gamma-2 herpesviruses, but also in several poxviruses. Moreover, recent data suggest that the K3-related protein of myxoma virus also downregulates MHC I. The presence of similar genes in eukaryotic genomes further indicates that the viral ORFs were originally derived from host genes of as yet unknown function. The molecular mechanism of MHC I downregulation by this novel gene family is only poorly understood at present. However, several lines of evidence suggest that they might function as ubiquitin ligases that regulate the intracellular transport of transmembrane proteins through ubiquitination.
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Affiliation(s)
- Klaus Früh
- Oregon Health and Science University, Vaccine and Gene Therapy Institute, 505 NW 185th Avenue, Beaverton, OR 97006, USA.
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32
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Borrello MG, Mercalli E, Perego C, Degl'Innocenti D, Ghizzoni S, Arighi E, Eroini B, Rizzetti MG, Pierotti MA. Differential interaction of Enigma protein with the two RET isoforms. Biochem Biophys Res Commun 2002; 296:515-22. [PMID: 12176011 DOI: 10.1016/s0006-291x(02)00886-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The receptor tyrosine kinase RET, with a known role in embryonic development and in human pathologies, is alternatively spliced to yield at least two functional isoforms, which differ only in their carboxyl terminal. Enigma protein is a member of the PDZ-LIM family and is known to interact with the short isoform of RET/PTC2, a chimeric oncoprotein isolated from papillary thyroid carcinoma. Here, we show that Enigma also interacts in intact cells with the short isoform of RET-wt and of its pathologic mutants associated to MEN2 syndromes, RET-C634R and RET-M918T. In contrast, Enigma binds all the corresponding RET long isoforms very poorly and colocalizes with short but not long RET/PTC2 isoforms. The RET docking tyrosine for Enigma is the last but one before the divergence between the two isoforms and we demonstrated that short-isoform-specific amino acid residues +2 to +4 to this tyrosine are required for the interaction of RET/PTC2 with Enigma.
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Affiliation(s)
- Maria Grazia Borrello
- Department of Experimental Oncology, Research Unit #3, Istituto Nazionale Tumori, Via Venezian 1, 20133 Milan, Italy.
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33
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Liu Y, Hair GA, Boden SD, Viggeswarapu M, Titus L. Overexpressed LIM mineralization proteins do not require LIM domains to induce bone. J Bone Miner Res 2002; 17:406-14. [PMID: 11874232 DOI: 10.1359/jbmr.2002.17.3.406] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Rat LIM mineralization protein 1 (LMP-1, an LIM domain protein) mediates bone morphogenetic protein 6 (BMP-6) induction of bone nodule formation in fetal rat calvarial osteoblast (ROB) cultures. We have isolated the complementary DNA (cDNA) for the human homologue of LMP-1 from an adult human heart cDNA library and showed that when overexpressed it is osteoinductive in the same culture system. The recently revised cDNA sequence of Enigma, the protein product of which binds to the insulin receptor and the tyrosine kinase receptor ret, now matches the nucleotide sequence of human LMP-1 (hLMP-1). A truncated, 223 amino acid (AA) LMP-1(t) protein has identical effects as the full-length protein, despite the deletion of the LIM domains. Two splice variants of human LMP-1 have been detected. Human LMP-2 has a 119-base pair (bp) deletion between bp 325 and 444 and a 17-bp insertion at bp 444. The resulting derived protein contains 423 AA with the LIM domains intact and does not induce bone formation when overexpressed in ROB cultures. Human LMP-3 has the same 17 nucleotide insertion at bp 444, resulting in a shift in the reading frame that causes a stop codon to occur at bp 505-507. The resulting 153 AA protein does not have the LIM domains, but overexpression of hLMP-3 induces bone formation in osteoblast cultures. These findings suggest that the LIM domains are not required for LMPs to induce bone formation. In addition, a small region (36 AA) of the LMP-1 protein may be required for bone formation.
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Affiliation(s)
- Yunshan Liu
- Department of Orthopaedic Surgery, Emory University School of Medicine, Decatur, Georgia, USA
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34
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Kotaka M, Lau YM, Cheung KK, Lee SM, Li HY, Chan WY, Fung KP, Lee CY, Waye MM, Tsui SK. Elfin is expressed during early heart development. J Cell Biochem 2001; 83:463-72. [PMID: 11596114 DOI: 10.1002/jcb.1244] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Elfin (previously named CLIM1) is a protein that possesses an N-terminal PDZ domain and a C-terminal LIM domain. It belongs to the family of Enigma proteins. Enigma proteins are a family of cytoplasmic proteins that contain an N-terminal PDZ domain and a series of C-terminal LIM domains. By virtue of these two protein interacting domains, Enigma proteins are capable of protein-protein interactions. It has been proposed that Enigma proteins may act as adapters between kinases and the cytoskeleton. We have previously shown that Elfin is most abundantly expressed in the heart and it colocalizes with alpha-actinin 2 at the Z-disks of the myocardium. In this report, Elfin was shown to localize at the actin stress fibers of myoblasts, as revealed by green fluorescent protein (GFP) tagging. In situ hybridization and immunostaining showed that Elfin expression begins at an early stage in mouse development and is present throughout the developing heart. Taken together, our experimental results suggest that Elfin may play an important role in myofibrillogenesis and heart development.
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Affiliation(s)
- M Kotaka
- Department of Biochemistry, The Chinese University of Hong Kong, Hong Kong
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35
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Tobias ES, Hurlstone AF, MacKenzie E, McFarlane R, Black DM. The TES gene at 7q31.1 is methylated in tumours and encodes a novel growth-suppressing LIM domain protein. Oncogene 2001; 20:2844-53. [PMID: 11420696 DOI: 10.1038/sj.onc.1204433] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2000] [Revised: 03/06/2001] [Accepted: 03/06/2001] [Indexed: 11/09/2022]
Abstract
Many studies suggest that a multi-tissue tumour suppressor gene is located at human chromosome 7q31.1. We have cloned and characterized a novel gene at this locus. The TES gene lies within the minimal region of overlap of several LOH studies and appears to possess the properties of a tumour suppressor. TES is widely expressed and is predicted to encode a protein of 421 amino acids, with three C-terminal LIM domains. Mutation analysis of the coding TES exons in 21 human tumour-derived cell lines revealed the presence of a frameshift mutation in one allele in the breast cancer cell line ZR-75. Methylation of the CpG island at the 5' end of TES appears to be a remarkably frequent finding, occurring in seven out of 10 ovarian carcinomas and in each of the 30 tumour-derived cell lines tested. Moreover, forced expression of TES in HeLa or OVCAR5 cells, resulted in a profound reduction in growth potential, as determined by the colony formation assay. We believe that TES is a tumour suppressor gene that is inactivated primarily by transcriptional silencing resulting from CpG island methylation.
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Affiliation(s)
- E S Tobias
- Beatson Institute for Cancer Research, CRC Beatson Laboratories, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
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36
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Abstract
Eleven distinct isoforms of phosphoinositide-specific phospholipase C (PLC), which are grouped into four subfamilies (beta, gamma, delta, and epsilon), have been identified in mammals. These isozymes catalyze the hydrolysis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] to inositol 1,4,5-trisphosphate and diacylglycerol in response to the activation of more than 100 different cell surface receptors. All PLC isoforms contain X and Y domains, which form the catalytic core, as well as various combinations of regulatory domains that are common to many other signaling proteins. These regulatory domains serve to target PLC isozymes to the vicinity of their substrate or activators through protein-protein or protein-lipid interactions. These domains (with their binding partners in parentheses or brackets) include the pleckstrin homology (PH) domain [PtdIns(3)P, beta gamma subunits of G proteins] and the COOH-terminal region including the C2 domain (GTP-bound alpha subunit of Gq) of PLC-beta; the PH domain [PtdIns(3,4,5)P3] and Src homology 2 domain [tyrosine-phosphorylated proteins, PtdIns(3,4,5)P3] of PLC-gamma; the PH domain [PtdIns(4,5)P2] and C2 domain (Ca2+) of PLC-delta; and the Ras binding domain (GTP-bound Ras) of PLC-epsilon. The presence of distinct regulatory domains in PLC isoforms renders them susceptible to different modes of activation. Given that the partners that interact with these regulatory domains of PLC isozymes are generated or eliminated in specific regions of the cell in response to changes in receptor status, the activation and deactivation of each PLC isoform are likely highly regulated processes.
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Affiliation(s)
- S G Rhee
- Laboratory of Cell Signaling, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892-0320, USA.
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37
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Human CLP36, a PDZ-domain and LIM-domain protein, binds to α-actinin-1 and associates with actin filaments and stress fibers in activated platelets and endothelial cells. Blood 2000. [DOI: 10.1182/blood.v96.13.4236] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractA 38-kd protein that associates with F-actin structures in activated platelets and endothelial cells was purified, cloned, and characterized. The protein contains an N-terminal PDZ motif, a large intervening sequence, and a C-terminal LIM domain and was identified as the human homolog of rat CLP36. The study showed that CLP36 associates with actin filaments and stress fibers that are formed during shape change and spreading of platelets and during migration and contraction of endothelial cells. CLP36 binds to α-actinin-1 as shown by coimmunoprecipitation, pull-down experiments, yeast 2-hybrid analysis, and blot overlay assays and colocalizes with α-actinin-1 along endothelial actin stress fibers. In contrast to α-actinin-1, CLP36 was absent from focal adhesions in both activated platelets and endothelial cells. The N-terminal part of CLP36 containing the PDZ domain and the intervening region, but not the LIM domain, targeted enhanced green fluorescent protein fusion proteins to stress fibers in endothelial cells. Yeast 2-hybrid analysis demonstrated that the intervening sequence, but not the PDZ or the LIM domain of CLP36, binds to the spectrinlike repeats 2 and 3 of α-actinin-1. The study further shows that CLP36 binds to α-actinin in resting platelets and translocates as a CLP36/α-actinin complex to the newly formed actin cytoskeleton in activated platelets. The results indicate that CLP36 binds via α-actinin-1 to actin filaments and stress fibers in activated human platelets and endothelial cells. The study suggests that CLP36 may direct α-actinin-1 to specific actin structures and at this position might modulate the function of α-actinin-1.
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38
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Human CLP36, a PDZ-domain and LIM-domain protein, binds to α-actinin-1 and associates with actin filaments and stress fibers in activated platelets and endothelial cells. Blood 2000. [DOI: 10.1182/blood.v96.13.4236.h8004236_4236_4245] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A 38-kd protein that associates with F-actin structures in activated platelets and endothelial cells was purified, cloned, and characterized. The protein contains an N-terminal PDZ motif, a large intervening sequence, and a C-terminal LIM domain and was identified as the human homolog of rat CLP36. The study showed that CLP36 associates with actin filaments and stress fibers that are formed during shape change and spreading of platelets and during migration and contraction of endothelial cells. CLP36 binds to α-actinin-1 as shown by coimmunoprecipitation, pull-down experiments, yeast 2-hybrid analysis, and blot overlay assays and colocalizes with α-actinin-1 along endothelial actin stress fibers. In contrast to α-actinin-1, CLP36 was absent from focal adhesions in both activated platelets and endothelial cells. The N-terminal part of CLP36 containing the PDZ domain and the intervening region, but not the LIM domain, targeted enhanced green fluorescent protein fusion proteins to stress fibers in endothelial cells. Yeast 2-hybrid analysis demonstrated that the intervening sequence, but not the PDZ or the LIM domain of CLP36, binds to the spectrinlike repeats 2 and 3 of α-actinin-1. The study further shows that CLP36 binds to α-actinin in resting platelets and translocates as a CLP36/α-actinin complex to the newly formed actin cytoskeleton in activated platelets. The results indicate that CLP36 binds via α-actinin-1 to actin filaments and stress fibers in activated human platelets and endothelial cells. The study suggests that CLP36 may direct α-actinin-1 to specific actin structures and at this position might modulate the function of α-actinin-1.
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39
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Gay F, Anglade I, Gong Z, Salbert G. The LIM/homeodomain protein islet-1 modulates estrogen receptor functions. Mol Endocrinol 2000; 14:1627-48. [PMID: 11043578 DOI: 10.1210/mend.14.10.0538] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
LIM/Homeodomain (HD) proteins are classically considered as major transcriptional regulators which, in cooperation with other transcription factors, play critical roles in the developing nervous system. Among LIM/HD proteins, Islet-1 (ISL1) is the earliest known marker of motoneuron differentiation and has been extensively studied in this context. However, ISL1 expression is not restricted to developing motoneurons. In both embryonic and adult central nervous system of rodent and fish, ISL1 is found in discrete brain areas known to express the estrogen receptor (ER). These observations led us to postulate the possible involvement of ISL1 in the control of brain functions by steroid hormones. Dual immunohistochemistry for ISL1 and ER provided evidence for ISL1-ER coexpression by the same neuronal subpopulation within the rat hypothalamic arcuate nucleus. The relationship between ER and ISL1 was further analyzed at the molecular level and we could show that 1) ISL1 directly interacts in vivo and in vitro with the rat ER, as well as with various other nuclear receptors; 2) ISL1-ER interaction is mediated, at least in part, by the ligand binding domain of ER and is significantly strengthened by estradiol; 3) as a consequence, ISL1 prevents ER dimerization in solution, thus leading to a strong and specific inhibition of ER DNA binding activity; 4) ISL1, via its N-terminal LIM domains, specifically inhibits the ER-driven transcriptional activation in some promoter contexts, while ER can serve as a coactivator for ISL1 in other promoter contexts. Taken together, these data suggest that ISL1-ER cross-talk could differentially regulate the expression of ER and ISL1 target genes.
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Affiliation(s)
- F Gay
- Equipe Information et Programmation Cellulaire, UMR 6026 Centre Nationale de la Recherche Scientifique, Université de Rennes I, France
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40
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Tanahashi H, Tabira T. Alzheimer's disease-associated presenilin 2 interacts with DRAL, an LIM-domain protein. Hum Mol Genet 2000; 9:2281-9. [PMID: 11001931 DOI: 10.1093/oxfordjournals.hmg.a018919] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Using the yeast two-hybrid system, we screened for proteins interacting with presenilin 2 (PS2) and cloned DRAL. DRAL is an LIM-only protein containing four LIM domains and an N-terminal half LIM domain. Previously DRAL has been cloned as a co-activator of the androgen receptor and as a protein interacting with a DNA replication regulatory protein, hCDC47. Our yeast two-hybrid assay showed that DRAL interacted with a hydrophilic loop region (amino acids 269-298) in the endoproteolytic N-terminal fragment of PS2, but not that of PS1, although the region 269-298 of PS2 and the corresponding PS1 sequence differ by only three amino acids. Each point mutation within this region, R275A, T280A, Q282A, R284A, N285A, P287T, I288L, F289A and S296A, in PS2 abolished the binding. This suggests that DRAL recognizes the PS2 structure specifically. The in vitro interaction was confirmed by affinity column assay and the physiological interactions between endogenous PS2 and DRAL by co-immunoprecipitation from human lung fibroblast MRC5 cells. Furthermore, in PS2-overexpressing HEK293 cells, we found an increase in the amount of DRAL in the membrane fraction and an increase in the amount of DRAL that was co-immunoprecipitated with PS2. The potential role of DRAL in the cellular signaling suggests that DRAL functions as an adaptor protein that links PS2 to an intracellular signaling.
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Affiliation(s)
- H Tanahashi
- Division of Demyelinating Disease and Aging, National Institute of Neuroscience, 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8502, Japan.
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Fu SL, Waha A, Vogt PK. Identification and characterization of genes upregulated in cells transformed by v-Jun. Oncogene 2000; 19:3537-45. [PMID: 10918612 DOI: 10.1038/sj.onc.1203691] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The transcription factor Jun (c-Jun) functions as a recipient of extracellular growth signals and converts them into patterns of gene expression. An oncogenic variant of c-Jun was isolated from the acutely transforming retrovirus ASV17. Overexpression of this viral Jun (v-Jun) induces transformation of chicken embryo fibroblasts (CEF) in culture and fibrosarcomas in chickens. v-Jun is a constitutively active form of c-Jun and transforms cells presumably by deregulating the expression of specific target genes. In this report, we describe six genes whose transcripts are upregulated in v-Jun-transformed CEF. Three of these genes show homology to known mammalian genes, to MAP kinase phosphatase 2 (MKP-2), to reversion-induced LIM protein (RIL) and to cytokine-inducible SH2-containing protein (CIS). Northern blot analysis, using CEF infected with various Jun mutants or an estrogen-regulatable Jun chimera, revealed distinct induction patterns of individual targets by v-Jun. The chicken RIL homolog showed an expression pattern tightly correlated with the activity of v-Jun. Its expression is also transformation-dependent, suggesting a role for this gene in v-Jun transformation. The newly identified v-Jun targets can serve as molecular markers in the v-Jun transformation process. Oncogene (2000) 19, 3537 - 3545
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Affiliation(s)
- S L Fu
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, BCC239, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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Christerson LB, Vanderbilt CA, Cobb MH. MEKK1 interacts with alpha-actinin and localizes to stress fibers and focal adhesions. CELL MOTILITY AND THE CYTOSKELETON 2000; 43:186-98. [PMID: 10401575 DOI: 10.1002/(sici)1097-0169(1999)43:3<186::aid-cm2>3.0.co;2-1] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mitogen-activated protein (MAP) kinases orchestrate the effects of many extracellular stimuli on cells. The serine/threonine protein kinase MEKK1 is an upstream activator of the MAP kinases c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK), extracellular signal-regulated kinase (ERK), and p38 as well as NF-kappa B. In a yeast two-hybrid interaction screen to identify proteins that bind to an N-terminal fragment of MEKK1 (amino acids 1-719), the actin-crosslinking protein alpha-actinin was identified as a MEKK1-binding protein. Over-expressed MEKK1 co-immunoprecipitated with alpha-actinin in cell lysates. Both endogenous and over-expressed MEKK1 colocalized with alpha-actinin along actin stress fibers and at focal adhesions. Residues 221-559 of MEKK1 bound to purified alpha-actinin in vitro, indicating that the interaction is direct, and this fragment localized to actin filaments in cells. MEKK1 kinase activity was not required for association with actin filaments, because a catalytically inactive mutant of MEKK1 (MEKK1 D1369A) localized to stress fibers. These results provide strong evidence for the interaction between MEKK1 and alpha-actinin. Thus, restriction of the kinase to the actin cytoskeleton may serve to regulate its specificity towards downstream targets.
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Affiliation(s)
- L B Christerson
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235, USA
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43
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Kotaka M, Kostin S, Ngai S, Chan K, Lau Y, Lee SM, Li HY, Ng EK, Schaper J, Tsui SK, Fung KP, Lee CY, Waye MM. Interaction of hCLIM1, an enigma family protein, with alpha-actinin 2. J Cell Biochem 2000; 78:558-65. [PMID: 10861853 DOI: 10.1002/1097-4644(20000915)78:4<558::aid-jcb5>3.0.co;2-i] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Enigma proteins are proteins that possess a PDZ domain at the amino terminal and one to three LIM domains at the carboxyl terminal. They are cytoplasmic proteins that are involved with the cytoskeleton and signal transduction pathway. By virtue of the two protein interacting domains, they are capable of protein-protein interactions. Here we report a study on a human Enigma protein hCLIM1, in particular. Our study describes the interaction of the human 36 kDa carboxyl terminal LIM domain protein (hCLIM1), the human homologue of CLP36 in rat, with alpha-actinin 2, the skeletal muscle isoform of alpha-actinin. hCLIM1 protein was shown to interact with alpha-actinin 2 by yeast two-hybrid screening and immunochemical analyses. Yeast two-hybrid analyses also demonstrated that the LIM domain of hCLIM1 binds to the EF-hand region of alpha-actinin 2, defining a new mode of LIM domain interactions. Immunofluorescent study demonstrates that hCLIM1 colocalizes with alpha-actinin at the Z-disks in human myocardium. Taken together, our experimental results suggest that hCLIM1is a novel cytoskeletal protein and may act as an adapter that brings other proteins to the cytoskeleton.
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Affiliation(s)
- M Kotaka
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
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44
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Passier R, Richardson JA, Olson EN. Oracle, a novel PDZ-LIM domain protein expressed in heart and skeletal muscle. Mech Dev 2000; 92:277-84. [PMID: 10727866 DOI: 10.1016/s0925-4773(99)00330-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In order to identify novel genes enriched in adult heart, we performed a subtractive hybridization for genes expressed in mouse heart but not in skeletal muscle. We identified two alternative splicing variants of a novel PDZ-LIM domain protein, which we named Oracle. Both variants contain a PDZ domain at the amino-terminus and three LIM domains at the carboxy-terminus. Highest homology of Oracle was found with the human and rat enigma proteins in the PDZ domain (62 and 61%, respectively) and in the LIM domains (60 and 69%, respectively). By Northern hybridization analysis, we showed that expression is highest in adult mouse heart, low in skeletal muscle and undetectable in other adult mouse tissues. In situ hybridization in mouse embryos confirmed and extended these data by showing high expression of Oracle mRNA in atrial and ventricular myocardial cells from E8.5. From E9.5 low expression of Oracle mRNA was detectable in myotomes. These data suggest a role for Oracle in the early development and function of heart and skeletal muscle.
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Affiliation(s)
- R Passier
- Department of Molecular Biology, Hamon Center for Basic Cancer Research, The University of Texas, Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd., Dallas, TX 75235-9148, USA
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45
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Cuppen E, van Ham M, Wansink DG, de Leeuw A, Wieringa B, Hendriks W. The zyxin-related protein TRIP6 interacts with PDZ motifs in the adaptor protein RIL and the protein tyrosine phosphatase PTP-BL. Eur J Cell Biol 2000; 79:283-93. [PMID: 10826496 DOI: 10.1078/s0171-9335(04)70031-x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The small adaptor protein RIL consists of two segments, the C-terminal LIM and the N-terminal PDZ domain, which mediate multiple protein-protein interactions. The RIL LIM domain can interact with PDZ domains in the protein tyrosine phosphatase PTP-BL and with the PDZ domain of RIL itself. Here, we describe and characterise the interaction of the RIL PDZ domain with the zyxin-related protein TRIP6, a protein containing three C-terminal LIM domains. The second LIM domain in TRIP6 is sufficient for a strong interaction with RIL. A weaker interaction with the third LIM domain in TRIP6, including the proper C-terminus, is also evident. TRIP6 also interacts with the second out of five PDZ motifs in PTP-BL. For this interaction to occur both the third LIM domain and the proper C-terminus are necessary. RNA expression analysis revealed overlapping patterns of expression for TRIP6, RIL and PTP-BL, most notably in tissues of epithelial origin. Furthermore, in transfected epithelial cells TRIP6 can be co-precipitated with RIL and PTP-BL PDZ polypeptides, and a co-localisation of TRIP6 and RIL with Factin structures is evident. Taken together, PTP-BL, RIL and TRIP6 may function as components of multi-protein complexes at actin-based sub-cellular structures.
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Affiliation(s)
- E Cuppen
- Department of Cell Biology, Institute of Cellular Signalling, University of Nijmegen, The Netherlands
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46
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Abstract
The LIM domain is a zinc finger structure that is present in several types of proteins, including homeodomain transcription factors, kinases and proteins that consist of several LIM domains. Proteins containing LIM domains have been discovered to play important roles in a variety of fundamental biological processes including cytoskeleton organization, cell lineage specification and organ development, but also for pathological functions such as oncogenesis, leading to human disease. The LIM domain has been demonstrated to be a protein-protein interaction motif that is critically involved in these processes. The recent isolation and analysis of more LIM domain-containing proteins from several species have confirmed and broadened our knowledge about LIM protein function. Furthermore, the identification and characterization of factors that interact with LIM domains illuminates mechanisms of combinatorial developmental regulation.
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Affiliation(s)
- I Bach
- Center for Molecular Neurobiology, University of Hamburg, Martinistrasse 85, 20246, Hamburg, Germany.
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Shen Y, Lyons P, Cooley M, Davidson D, Veillette A, Salgia R, Griffin JD, Schaller MD. The noncatalytic domain of protein-tyrosine phosphatase-PEST targets paxillin for dephosphorylation in vivo. J Biol Chem 2000; 275:1405-13. [PMID: 10625692 DOI: 10.1074/jbc.275.2.1405] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The noncatalytic domain of protein-tyrosine phosphatase (PTP)-PEST contains a binding site for the focal adhesion-associated protein paxillin. This binding site has been narrowed to a 52-residue sequence that is composed of two nonoverlapping, weak paxillin binding sites. The PTP-PEST binding site on paxillin has been mapped to the two carboxyl-terminal LIM (lin11, isl-1, and mec-3) domains. Transient expression of PTP-PEST reduced tyrosine phosphorylation of p130(cas), as anticipated. A PTP-PEST mutant defective for binding p130(cas) does not cause a reduction in its tyrosine phosphorylation in vivo. Expression of PTP-PEST also caused a reduction of phosphotyrosine on paxillin. Expression of mutants of PTP-PEST with deletions in the paxillin-binding site did not associate with paxillin in vivo and failed to cause a reduction in the phosphotyrosine content of paxillin. These results demonstrate that paxillin can serve as a PTP-PEST substrate in vivo and support the model that a noncatalytic domain interaction recruits paxillin to PTP-PEST to facilitate its dephosphorylation.
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Affiliation(s)
- Y Shen
- Department of Cell Biology & Anatomy, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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48
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Brown MC, Turner CE. Characterization of paxillin LIM domain-associated serine threonine kinases: Activation by angiotensin II in vascular smooth muscle cells. J Cell Biochem 2000. [DOI: 10.1002/(sici)1097-4644(20000101)76:1<99::aid-jcb10>3.0.co;2-m] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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49
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Thomas JW, Cooley MA, Broome JM, Salgia R, Griffin JD, Lombardo CR, Schaller MD. The role of focal adhesion kinase binding in the regulation of tyrosine phosphorylation of paxillin. J Biol Chem 1999; 274:36684-92. [PMID: 10593973 DOI: 10.1074/jbc.274.51.36684] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Focal adhesion kinase (FAK) and paxillin are focal adhesion-associated, phosphotyrosine-containing proteins that physically interact. A previous study has demonstrated that paxillin contains two binding sites for FAK. We have further characterized these two binding sites and have demonstrated that the binding affinity of the carboxyl-terminal domain of FAK is the same for each of the two binding sites. The presence of both binding sites increases the affinity for FAK by 5-10-fold. A conserved paxillin sequence called the LD motif has been implicated in FAK binding. We show that mutations in the LD motifs in both FAK-binding sites are required to dramatically impair FAK binding in vitro. A paxillin mutant containing point mutations in both FAK-binding sites was characterized. The mutant exhibited reduced levels of phosphotyrosine relative to wild type paxillin in subconfluent cells growing in culture, following cell adhesion to fibronectin and in src-transformed fibroblasts. These results suggest that paxillin must bind FAK for maximal phosphorylation in response to cell adhesion and that FAK may function to direct tyrosine phosphorylation of paxillin in the process of transformation by the src oncogene.
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Affiliation(s)
- J W Thomas
- Department of Cell Biology and Anatomy, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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50
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Brown S, McGrath MJ, Ooms LM, Gurung R, Maimone MM, Mitchell CA. Characterization of two isoforms of the skeletal muscle LIM protein 1, SLIM1. Localization of SLIM1 at focal adhesions and the isoform slimmer in the nucleus of myoblasts and cytoplasm of myotubes suggests distinct roles in the cytoskeleton and in nuclear-cytoplasmic communication. J Biol Chem 1999; 274:27083-91. [PMID: 10480922 DOI: 10.1074/jbc.274.38.27083] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have cloned and characterized a novel isoform of the skeletal muscle LIM protein 1 (SLIM1), designated SLIMMER. SLIM1 contains an N-terminal single zinc finger followed by four LIM domains. SLIMMER is identical to SLIM1 over the first three LIM domains but contains a novel C-terminal 96 amino acids with three potential bipartite nuclear localization signals, a putative nuclear export sequence, and 27 amino acids identical to the RBP-J binding region of KyoT2, a murine isoform of SLIM1. SLIM1 localized to the cytosol of Sol8 myoblasts and myotubes. SLIMMER was detected in the nucleus of myoblasts and, following differentiation into myotubes, was exclusively cytosolic. Recombinant green fluorescent protein-SLIM1 localized to the cytoplasm and associated with focal adhesions and actin filaments in COS-7 cells, while green fluorescent protein-SLIMMER was predominantly nuclear. SLIMMER truncation mutants revealed that the first nuclear localization signal mediates nuclear localization. The addition of the proposed nuclear export sequence decreased the level of exclusively nuclear expression and increased cytosolic SLIMMER expression in COS-7 cells. The leucine-rich nuclear export signal was required for the export of SLIMMER from the nucleus of myoblasts to the cytoplasm of myotubes. Collectively, these results suggest distinct roles for SLIM1 and SLIMMER in focal adhesions and nuclear-cytoplasmic communication.
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Affiliation(s)
- S Brown
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia 3168
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