GnRH gene products downregulate their neighboring genes encoding protein tyrosine phosphatases

The decapeptide gonadotropin-releasing hormone (GnRH) has multiple functions, including the regulation of gonadotropin secretion, reproductive behavior, and cell proliferation. In this paper, we have found that in the medaka (Oryzias latipes) genome, gonadotropin-releasing hormone (GnRH) genes are adjacent to type IV protein tyrosine phosphatase (PTP) genes encoding PTPα and PTPε, which are known to regulate cellular activity via interacting with voltage-gated potassium channel. We have subsequently demonstrated using an in vitro medaka whole-brain culture system that GnRH downregulates the PTPα and PTPε gene expression. Inhibition of intracellular type IV PTP signaling, which probably results in the modulation of cellular activity, may account for multiplicity of GnRH function.