Expression of the c-kit Gene is Critical for Migration of Neonatal Rat Gonocytes in Vitro1

Abstract

Rat gonocytes migrate to the basement membrane during the first postnatal week, a change in position crucial for their survival. These cells express the c-kit gene from the day of birth through Day 5 in vivo and develop the ability to migrate in Sertoli cell-gonocyte cocultures. In this study, we asked whether c-kit expression and synthesis of Kit protein are required for pseudopod production by gonocytes in vitro. To determine whether gonocyte migration in vitro is invariably accompanied by c-kit expression, we quantified percentages of gonocytes expressing c-kit with increasing time in vitro and correlated these data with pseudopod development by individual cells. We also determined the effect of exposure to Kit antibodies on gonocyte migration in vitro, and, conversely, asked whether addition of exogenous stem cell factor (SCF), the Kit ligand, stimulates pseudopod development. We found that 1) increasing numbers of gonocytes express c-kit with increasing time in vitro; 2) once these cells begin migrating in vitro, the appearance of a pseudopod on a gonocyte is absolutely correlated with kit expression by that cell; 3) incubating cocultures with Kit antibodies significantly reduces the number of cells with pseudopods, without any detectable decrease in numbers of gonocytes; and 4) addition of exogenous SCF to cocultures prepared on Day 5 results in a transient but significant increase in the percentage of gonocytes with pseudopods even though we found that Sertoli cells in the cultures produce endogenous SCF. Thus, our findings provide evidence to support a role for c-kit expression by neonatal gonocytes and, presumably, SCF expression by neonatal Sertoli cells in stimulating migration of these germ cells in vitro.

Stem Cell Factor/c-kit Up-regulates Cyclin D3 and Promotes Cell Cycle Progression via the Phosphoinositide 3-Kinase/p70 S6 Kinase Pathway in Spermatogonia

“…Recently, PKC-and AKT, two important regulators of cell growth, have been demonstrated to mediate the PI3-K signaling to p70S6K. A study with neonatal rat gonocytes, which are the precursors of type A spermatogonia and express c-kit (19), demonstrated that PKC-is co-expressed with PI3-K (20). Western blotting showed that PKC-is expressed in mouse spermatogonia (Fig.…”

NOTCH signaling in Sertoli cells regulates gonocyte fate

“…KIT is then re-expressed in a fraction of gonocytes after birth and is thought to mediate their migration toward the basement membrane. [69][70][71] While spermatogonial stem cells and other undifferentiated spermatogonia do not express KIT, this molecule is expressed in all differentiating spermatogonia in the first wave of spermatogenesis and in the adult. 72 Our microarray data set (GSE37073) revealed that Kit transcripts were upregulated in AMH-NICD1 to levels 1.63 times those of the controls at E14.5 (p = 2.45 × 10 -2 ).…”

Cycling to and from a stem cell niche: the temporal and spatial odyssey of mitotic male germ cells

“…Such migration is necessary for the further development of male germ cells, as gonocytes that remain in the lumen after P5 undergo apoptosis (Tres and Kierszenbaum, 2005). Studies on KIT suggest that it may be one of many factors that mediate this process (Orth et al, 1997). Antibodies that blocked KIT on gonocytes in vitro decreased the number of cells with detectable pseudopods available for motility (Orth et al, 1997).…”

“…Studies on KIT suggest that it may be one of many factors that mediate this process (Orth et al, 1997). Antibodies that blocked KIT on gonocytes in vitro decreased the number of cells with detectable pseudopods available for motility (Orth et al, 1997). Additional factors that may influence gonocyte migration include members of the ADAM (A Disintegrin And Metalloprotease), integrin, and tetraspanin families.…”