Proper development and function of the anterior pituitary gland is critical for multiple physiological processes including growth, metabolism and reproduction. The mature anterior pituitary gonadotrope serves as a control center for the integration of hormonal signals in the regulation of reproduction. Gonadotrope development requires highly orchestrated transcriptional programs utilizing the coordinated activity of regulatory proteins to generate the terminally differentiated state;yet the mechanisms for gonadotrope maturation remain to be fully elucidated. The goal of this application is to investigate transcriptional regulation by homeodomain repressor Msx1 in gonadotrope differentiation and development. The decline of Msx1 expression coincides with the onset of expression of lineage-specific pituitary transcription factors 1GSU and GnRHR. My hypothesis is that Msx1 functions as a negative regulator in early pituitary development by repressing the early gonadotrope-specific genes: the common 1-subunit (1GSU) and GnRH receptor (GnRHR), thus coordinating the onset of the gonadotrope-specific gene program.
Aim 1 will address the physiological relevance of Msx1 in 1GSU and GnRHR repression in the developing pituitary both in vitro and in vivo.
Aim 2 will investigate the roles of Msx1 corepressors, the Transducin-Like Enhancer of split (TLE) proteins, their recruitment by Msx1, and the role of these recruitment events for 1GSU and GnRHR repression during gonadotrope differentiation. Finally, Aim 3 will delineate the functions of Msx1 and its cofactors in the maturation of the gonadotrope by epigenetic technologies. Overall, by utilizing our innovative cell lineage models, genomics, and genetically modified mice, these studies will provide novel insights into the molecular mechanisms of pituitary development and the onset of gonadotrope-specific gene programs.
Homeodomain transcription factors are crucial for pituitary organogenesis and cellular differentiation. The main goal of this proposal is to investigate the role of the homeodomain repressor Msx1 during pituitary development and the onset of gonadotrope-specific gene programs by utilizing an ensemble of differentiated pituitary cell models, in vivo genetics, molecular methods, and epigenetic approaches. This research will provide insight into novel regulatory mechanisms and significantly advance our understanding of gonadotrope differentiation and maturation.
|Xie, Huimin; Hoffmann, Hanne M; Iyer, Anita K et al. (2017) Chromatin status and transcription factor binding to gonadotropin promoters in gonadotrope cell lines. Reprod Biol Endocrinol 15:86|
|Xie, Huimin; Hoffmann, Hanne M; Meadows, Jason D et al. (2015) Homeodomain Proteins SIX3 and SIX6 Regulate Gonadotrope-specific Genes During Pituitary Development. Mol Endocrinol 29:842-55|
|Hoffmann, Hanne M; Tamrazian, Anika; Xie, Huimin et al. (2014) Heterozygous deletion of ventral anterior homeobox (vax1) causes subfertility in mice. Endocrinology 155:4043-53|
|Xie, Huimin; Cherrington, Brian D; Meadows, Jason D et al. (2013) Msx1 homeodomain protein represses the ?GSU and GnRH receptor genes during gonadotrope development. Mol Endocrinol 27:422-36|