title: INF2- and FHOD-related formins promote ovulation in the somatic gonad of C. elegans.
abstract: Formins are regulators of actin filament dynamics. We demonstrate here that two formins, FHOD-1 and EXC-6, are important in the nematode Caenorhabditis elegans for ovulation, during which actomyosin contractions push a maturing oocyte from the gonad arm into a distensible bag-like organ, the spermatheca. EXC-6, a homolog of the disease-associated mammalian formin INF2, is highly expressed in the spermatheca, where it localizes to cell-cell junctions and to circumferential actin filament bundles. Loss of EXC-6 does not noticeably affect the organization the actin filament bundles, and causes only a very modest increase in the population of junction-associated actin filaments. Despite absence of a strong cytoskeletal phenotype, approximately half of ovulations in exc-6 mutants exhibit extreme defects, including failure of the oocyte to enter the spermatheca, or breakage of the oocyte as the distal spermatheca entrance constricts during ovulation. Loss of FHOD-1 alone has little effect, and we cannot detect FHOD-1 in the spermatheca. However, combined loss of these formins in double fhod-1;exc-6 mutants results in profound ovulation defects, with significant slowing of the entry of oocytes into the spermatheca, and failure of nearly 80% of ovulations. We suggest that EXC-6 plays a role directly in the spermatheca, perhaps by modulating the ability of the spermatheca wall to rapidly accommodate an incoming oocyte, while FHOD-1 may play an indirect role relating to its known importance in the growth and function of the egg-laying muscles. © 2016 The Authors. Cytoskeleton Published by Wiley Periodicals, Inc.
authors: Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York, 13210.
authors: Anna
authors: A
authors: Hegsted
authors: Department of Pharmacology, State University of New York Upstate Medical University, Syracuse, New York, 13210.
authors: Forrest A
authors: FA
authors: Wright
authors: Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York, 13210.
authors: SarahBeth
authors: S
authors: Votra
authors: Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York, 13210.
authors: David
authors: D
authors: Pruyne
mesh_terms: D008841:Actin Cytoskeleton / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D000080865:Formins; D008297:Male; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism*; D010060:Ovulation / Q000235:genetics / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins; C000598635:EXC-6 protein, C elegans; D000080865:Formins; D008840:Microfilament Proteins; C575257:fhod-1 proteins, C elegans
keywords: EXC-6; FHOD-1; actin; cell-cell junctions; reproductive defects; spermatheca