Identification and functional validation of novel enhancer sequences involved in pituitary gland development and pathology
There is a fundamental gap in understanding how the GPR101 gene regulates human growth in physiological and pathological conditions. Children’s growth is remarkably clinical relevant and is an important indicator of their health and general well-being. The specific objective of this proposal is to identify the molecular mechanisms underlying GPR101 overexpression in the pituitary tumors of children with GPR101 duplications causing X-linked acrogigantism (X-LAG).
My central hypothesis is that GPR101 duplications disrupt the structure of the local chromatin, leading to the creation of a new chromatin domain where de novo enhancer-promoter interactions take place, causing abnormal GPR101 expression. This hypothesis will be tested by pursuing three specific aims:
1.	Elucidate the transcriptional regulation of GPR101 in normal and pathological conditions
2.	Identify and functionally characterize novel pituitary-specific enhancer sequences
3.	Investigate these regulatory sequences in patients with different pituitary pathologies.
To achieve aim 1) I will perform an in vitro functional characterization of GPR101 promoter: promoter activity will be studied by luciferase-based reporter assays, by conducting a methylation analysis, and by determining its accessibility to transcription factors.
To achieve aim 2) I will  validate my preliminary results showing the formation of a novel chromatin domain by 4C-Seq. Four putative enhancer sequences located within the duplicated GPR10 region and identified in silico will be functionally evaluated in vitro to establish their impact on transcriptional activity. To identify novel pituitary-specific enhancers, a whole-genome profile of enhancer-specific histone marks will be performed in normal and tumoral pituitary cells by ChIP-Seq.
To achieve aim 3) I will screen patients with different pituitary disorders for mutations (Sanger sequencing) and structural variations (CNV assays) in the functionally-verified enhancers.