ABSTRACT
Activins, members of the TGFbeta family of proteins, are widely expressed in a variety of tissues. First identified based on their ability to regulate biosynthesis and secretion of follicle-stimulating hormone (FSH), activins have also been shown to modulate development, cell growth, apoptosis, and inflammation. Despite their many known functions, the precise mechanisms and downstream signaling pathways by which activins mediate their diverse effects remain unknown. We have used a DNA microarray assay to identify genes that are regulated by activin, alone or in combination with gonadotropin-releasing hormone (GnRH), another major regulator of FSH, in a murine gonadotrope-derived cell line (LbetaT2). We used mRNA from these cells to screen Affymetrix Mu74av2 mouse Gene Chip oligonucleotide microarrays, representing approximately 12,400 mouse genes. Treatment of LbetaT2 cells with activin A, a gonadotropin-releasing hormone agonist (GnRHA) or activin A plus GnRHA resulted in alterations in levels of gene expression that ranged in magnitude from 15 to 67-fold. Data analysis identified 268 transcripts that were up- or down-regulated by two-fold or more. Distinct sets of genes were affected by treatment with activin, GnRHA and activin plus GnRHA, suggesting interactions between activin and GnRHA. Changes in expression of seven randomly selected representative genes identified by the microarray technique were confirmed by real-time quantitative PCR and semi-quantitative reverse transcription/PCR (RT/PCR). Modulation of expression of genes by activin suggests that activin may mediate its effects through a variety of signaling pathways.
