The GEX-2 and GEX-3 proteins are required for tissue morphogenesis and cell migrations in C. elegans (original) (raw)

  1. Martha C. Soto1,2,5,
  2. Hiroshi Qadota3,5,
  3. Katsuhisa Kasuya3,
  4. Makiko Inoue3,
  5. Daisuke Tsuboi3,4,
  6. Craig C. Mello1,2,6, and
  7. Kozo Kaibuchi3,4
  8. 1Program in Molecular Medicine and Cell Biology,2Howard Hughes Medical Institute, University of Massachusetts Cancer Center, Worcester, Massachusetts 01605, USA; 3Division of Signal Transduction, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0101, Japan;4Department of Cell Pharmacology, Nagoya University, Graduate School of Medicine, Showa, Nagoya, Aichi 466-8550, Japan

Abstract

During body morphogenesis precisely coordinated cell movements and cell shape changes organize the newly differentiated cells of an embryo into functional tissues. Here we describe two genes, gex-2 and_gex-3_, whose activities are necessary for initial steps of body morphogenesis in Caenorhabditis elegans. In the absence of_gex-2_ and gex-3 activities, cells differentiate properly but fail to become organized. The external hypodermal cells fail to spread over and enclose the embryo and instead cluster on the dorsal side. Postembryonically gex-3 activity is required for egg laying and for proper morphogenesis of the gonad. GEX-2 and GEX-3 proteins colocalize to cell boundaries and appear to directly interact. GEX-2 and GEX-3 are highly conserved, with vertebrate homologs implicated in binding the small GTPase Rac and a GEX-3_Drosophila_ homolog, HEM2/NAP1/KETTE, that interacts genetically with Rac pathway mutants. Our findings suggest that GEX-2 and GEX-3 may function at cell boundaries to regulate cell migrations and cell shape changes required for proper morphogenesis and development.

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