TwoCaenorhabditis eleganscalponin-related proteins have overlapping functions that maintain cytoskeletal integrity and are essential for reproduction

• Type of Material: Article
• Authors: Shoichiro Ono, Emory University; Kanako Ono, Emory University
• Language: English
• Date: 2020-08-21
• Publisher: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
• Publication Version: Final Published Version
• Copyright Statement: © 2020 Ono and Ono.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1074/jbc.RA120.014133
• Title of Journal or Parent Work: JOURNAL OF BIOLOGICAL CHEMISTRY
• Volume: 295
• Issue: 34
• Start Page: 12014
• End Page: 12027
• Grant/Funding Information: This work was supported by National Institutes of Health Grant R01 AR048615 (to S. O.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
• Keywords: actomyosin contractility; cytoskeleton; elegans); GENE ENCODES; Science & Technology; UNC-87; filament dynamics actin; C. ELEGANS; UNC-60 GENE; calponin; tropomyosin; MUSCLE-CELLS; Biochemistry & Molecular Biology; CALPONIN HOMOLOGY DOMAINS; ovulation; OVULATORY CONTRACTION; DEPOLYMERIZING FACTOR/COFILIN PROTEINS; CAENORHABDITIS-ELEGANS; bundling; SEQUENCE-ANALYSIS; calponin-like (CLIK) motif; Life Sciences & Biomedicine; cofilin; Caenorhabditis elegans (C; MYOEPITHELIAL SHEATH; Actin
• Research Categories: Health Sciences, Oncology

Abstract

Published under license by The American Society for Biochemistry and Molecular Biology, Inc. Multicellular organisms have multiple genes encoding calponins and calponin-related proteins, some of which are known to regulate actin cytoskeletal dynamics and contractility. However, the functional similarities and differences among these proteins are largely unknown. In the nematode Caenorhabditis elegans, UNC-87 is a calponin-related protein with seven calponin-like (CLIK) motifs and is required for maintenance of contractile apparatuses in muscle cells. Here, we report that CLIK-1, another calponin-related protein that also contains seven CLIK motifs, functionally overlaps with UNC-87 in maintaining actin cytoskeletal integrity in vivo and has both common and different actin-regulatory activities in vitro We found that CLIK-1 is predominantly expressed in the body wall muscle and somatic gonad where UNC-87 is also expressed. unc-87 mutation caused cytoskeletal defects in the body wall muscle and somatic gonad, whereas clik-1 depletion alone caused no detectable phenotypes. However, simultaneous clik-1 and unc-87 depletion caused sterility due to ovulation failure by severely affecting the contractile actin networks in the myoepithelial sheath of the somatic gonad. In vitro, UNC-87 bundled actin filaments, whereas CLIK-1 bound to actin filaments without bundling them and antagonized UNC-87-mediated filament bundling. We noticed that UNC-87 and CLIK-1 share common functions that inhibit cofilin binding and allow tropomyosin binding to actin filaments, suggesting that both proteins stabilize actin filaments. In conclusion, partially redundant functions of UNC-87 and CLIK-1 in ovulation are likely mediated by their common actin-regulatory activities, but their distinct actin-bundling activities suggest that they also have different biological functions.