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Development. 2015 Oct 15;142(20):3549-60. doi: 10.1242/dev.127597. Epub 2015 Sep 22.

Polarized Rac-dependent protrusions drive epithelial intercalation in the embryonic epidermis of C. elegans.

Author information

1
Graduate Program in Genetics, University of Wisconsin-Madison, 1117 W. Johnson Street, Madison, WI 53706, USA.
2
Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, 101 Manning Drive, Chapel Hill, NC 27514, USA Center for Translational Cancer Research, Institute of Biosciences and Technology and Department of Medical Physiology, Texas A&M Health Science Center, 2121 W. Holcombe Boulevard, Houston, TX 77030, USA.
3
Graduate Program in Genetics, University of Wisconsin-Madison, 1117 W. Johnson Street, Madison, WI 53706, USA Department of Zoology, University of Wisconsin-Madison, 1117 W. Johnson Street, Madison, WI 53706, USA jdhardin@wisc.edu.

Abstract

Cell intercalation is a fundamental, coordinated cell rearrangement process that shapes tissues throughout animal development. Studies of intercalation within epithelia have focused almost exclusively on the localized constriction of specific apical junctions. Another widely deployed yet poorly understood alternative mechanism of epithelial intercalation relies on basolateral protrusive activity. Using the dorsal embryonic epidermis of Caenorhabditis elegans, we have investigated this alternative mechanism using high-resolution live cell microscopy and genetic analysis. We find that as dorsal epidermal cells migrate past one another they produce F-actin-rich protrusions polarized at their extending (medial) edges. These protrusions are controlled by the C. elegans Rac and RhoG orthologs CED-10 and MIG-2, which function redundantly to polarize actin polymerization upstream of the WAVE complex and WASP, respectively. We also identify UNC-73, the C. elegans ortholog of Trio, as a guanine nucleotide exchange factor (GEF) upstream of both CED-10 and MIG-2. Further, we identify a novel polarizing cue, CRML-1, which is the ortholog of human capping Arp2/3 myosin I linker (CARMIL), that localizes to the nonprotrusive lateral edges of dorsal cells. CRML-1 genetically suppresses UNC-73 function and, indirectly, actin polymerization. This network identifies a novel, molecularly conserved cassette that regulates epithelial intercalation via basolateral protrusive activity.

KEYWORDS:

CARMIL; Cell intercalation; LRRC16A; Morphogenesis; Rac GTPase; Trio

PMID:
26395474
PMCID:
PMC4631769
DOI:
10.1242/dev.127597
[Indexed for MEDLINE]
Free PMC Article

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