The pharynx of Caenorhabditis elegans is a simple, yet a powerful experimental model for the study of mechanisms regulating cell migration during organ development. There are five gland cells within the mature pharynx.[1,2] All of these cells send cytoplasmic extensions to more anterior locations in the pharynx where they connect with the pharyngeal lumen and release secretions that aid in digestion.[3] During development of the pharynx, the dorsal gland cell,
g1p, is born in the anterior aspect of the pharyngeal primordium and undergoes a form of morphogenesis called retrograde extension.[4,5,6] As the cell body migrates to the terminal bulb, a part of the cell body is left anchored in the anterior region of the pharynx. When migration is complete, a long extension is left behind the cell's migratory path. The objective of our research is to elucidate the molecular mechanism of this distinctive mode of gland cell migration.
egl-15, the single Fibroblast Growth Factor Receptor (FGFR) in C. elegans, and
ina-1, one of two a-integrin receptors, are required for the proper migration of
g1p cell.[5] Worms mutant for either
egl-15 or
ina-1 show similar defects where the gland cell bodies migrate past the terminal bulb, and are located in proximity of the intestine. Genetic epistasis and molecular studies will be used to explore the possibility of FGFR and integrin cross-talk, and more precisely determine the mechanism of receptor action during retrograde extension. Currently,
egl-15 null mutant transgenic rescue experiments are being performed with different EGL-15 domain deletions to distinguish the domain(s) that are required for gland cell migration. Transgenic rescue strategies will be used to locate the site of
egl-15 and
ina-1 expression and function. References: 1Altun ZF & Hall DH. 2009. In WormAtlas. oi:10.3908/wormatlas.1.3.; 2Albertson, DG & Thomson, JN. 1976. Philos Trans R Soc Lond B Biol Sci. 275: 299-325.; 3Smit RB, Schnabel R & Gaudet J. 2008. PLoS Genet. 4:
e1000222.; 4Sulston JE, Schierenberg E, White JG & Thomson JN. 1983. Dev Biol. 100:64-119.; 5Kormish J, Raharjo W, Kim S, Rohs P, Srayko M, & Gaudet J. in prep.; 6Heiman MG & Shaham S. 2009. Cell. 137:344-55.