RAT TESTICULAR N-CADHERIN - ITS COMPLEMENTARY DEOXYRIBONUCLEIC-ACID CLONING AND REGULATION

Using primer sets specific for mouse N-cadherin and rat testicular RNA for RT-PCR, a full-length complementary DNA (cDNA) coding for rat tes ticular N-cadherin was isolated. The deduced amino acid sequence of ra t N-cadherin yielded a 883-amino acid polypeptide that displayed a 98. 6% identity with the mouse homolog. N-Cadherin was found to be express ed by Sertoli and germ cells ill the rat testis by RT-PCR. Using Serto li-germ cell cocultures,:it was found that the N-cadherin expression i ncreased with time in culture. To assess whether this is due to a solu ble factor(s) released from germ cells that affects Sertoli cell N-cad herin expression, germ cell-conditioned media (GCCM) were fractionated by preparative anion-exchange HPLC, and the resulting fractions were divided into 14 pools. Pool 4 was found to contain a factor(s) that in duced a dose-dependent stimulation on Sertoli cell N-cadherin expressi on with a maximal stimulation at 2 mu g protein/dish/4.5 x 10(6) Serto li cells. At higher doses between 12 and 32 mu g protein/dish, this po ol relinquished its effect on Sertoli cell N-cadherin expression sugge stive of a biphasic effect. This biphasic effect was confirmed using i ncreasing doses of crude GCCM on Sertoli cell cultures. Since nonviabl e germ cells failed to stimulate Sertoli cell N-cadherin expression, i t illustrates the observed stimulatory effect by GCCM is likely to be mediated via a soluble factor(s) releasing from viable germ cells. The se results reveal the presence of a stimulatory factor(s) in GCCM that can modulate Sertoli cell N-cadherin expression in vitro. Since N-cad herin plays a crucial role in facilitating invasive capacity of metast atic tumor cells, the observation of germ cell-released factor(s) in a ffecting Sertoli cell N-cadherin expression may suggest its possible r ole in facilitating germ cell migration during spermatogenesis.