Abstract LB-266: SIRT1 governs GnRH neuron migration and The Kallmann syndrome phenotype.

Abstract

Abstract SIRT1 is a type III histone deacetylase, linked to diverse functions in a variety of physiological settings. SIRT1 is highly expressed in gonadogenesis and Sirt1−/− mice demonstrate infertility and die post-natally from a variety of abnormalities, including pancreas, lung, skeletal, and heart defects. Recent studies have shown reduced intratesticular testosterone levels in Sirt1−/− mice. The normal migration of GnRH neurons from the vomeronasal organ (VNO) to hypothalamus is required for their destined location where GnRH stimulates the anterior pituitary to secrete gonadotropins. A subset of genes has been found to be involved in this process. In the current studies, we investigated the function of the hypothalamic pituitary gonadal axis in Sirt1−/− mice. Herein, a GnRH stimulation test was conducted on Sirt1−/− mice or littermate controls. The addition of GnRH to Sirt1−/− mice resulted in an increase in testosterone, LH and FSH levels, to a level similar to physiological secretion in normal controls. Immunostaining of mouse E14.5 brain in sagittal sections demonstrated that most of the GnRH positive neurons migrated to the forebrain in Sirt1+/+ mice whereas in Sirt1−/- mice, all of GnRH neurons resided in the VNO region and are undetectable in the forebrain. Treatment of hypothalamic neuronal cell lines, GN11 cells or GT1-7 cells with either Sirtinol or Nicotinamide, reduced cell migration in wound-healing and Matrigel invasion assays, most dramatically in trans-well migration assays. Retroviral gene transduction of cells with an expression vector encoding SIRT1, enhanced wound closure and invasiveness while transduction with the SIRT1 H363Y mutant abrogated migration. Cortactin is an F-actin binding protein involved in cancer cell migration and neurite outgrowth. Immunoprecipitation of FLAG-tagged SIRT1 and subsequent Western blot analysis revealed the association of SIRT1 with cortactin. Inhibition of SIRT1 activity by trichostatin A (TSA) or Nicotinamide, increased cortactin acetylation in 3T3 Sirt1+/+ cells, while in 3T3 Sirt1−/− cells, Nicotinamide did not increase cortactin acetylation. Deacetylation of cortactin by SIRT1 may play a role in GnRH neuronal migration. These studies demonstrated the critical role of SIRT1 activity in GnRH neuron migration and invasion both in cultured cells and in vivo. Citation Format: Liping Wang, Gabriele Di Sante, Chenguang Wang, Michael J. Powell, Michael W. McBurney, Richard G. Pestell. SIRT1 governs GnRH neuron migration and The Kallmann syndrome phenotype. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-266. doi:10.1158/1538-7445.AM2013-LB-266