Identification of novel genes regulated by LH in the primate corpus luteum: insight into their regulation during the late luteal phase.

The process of luteinization, during which granulosa cells are transformed into luteal cells, is accompanied by dramatic changes in the response of luteal cells to LH. Although luteal cells require LH-cAMP signalling cascade for survival, whether these cells respond to trophic factors through changes in gene expression remains poorly characterized. In an attempt to characterize gonadotrophin (LH)-regulated gene expression in the bonnet monkey corpus luteum (CL), changes in gene expression after GnRH antagonist treatment to inhibit LH secretion, different stages of CL and during hCG-simulated early pregnancy were examined using differential display RT-PCR, Northern blot and semiquantitative RT-PCR analyses. We have identified seven non-redundant cDNA's whose expression were regulated by LH. The results show that inhibition of LH secretion not only leads to down-regulation in the expression of genes, e.g. low density lipoprotein (LDL) receptor and Aldose reductase, but expression of some of the genes was up-regulated, e.g. Humanin, RNA helicase, Lyric protein, Acidic ribosomal phosphoprotein and KIAA1750. mRNA levels of the genes identified as up-regulated after LH inhibition were higher during late compared to the early and mid-luteal phase CL, but treatment with hCG down-regulated their expressions. We conclude that we have identified novel genes (known and unknown) that are up or down-regulated by LH, and the results suggest that LH-mediated activation and repression of expression of many genes is central to the regulation of the structure and function of the CL in the monkey.