Discovery Pipeline for Genetic Defects in Hypothalamic-pituitary Development Using International Mouse Phenotyping Consortium Mice

摘要

Abstract Congenital hypopituitarism (CH) is a common birth defect frequently associated with syndromic abnormalities in the central nervous system, ocular structures, face, and gonads. The most severe disorders have midline developmental anomalies and include holoprosencephaly, which is usually embryonic lethal, or septo-optic dysplasia. Less severe birth defects disrupt only hypothalamic or pituitary development, causing hormone deficiencies that affect viability, growth, fertility, metabolism, and the stress response, and may require life-long care. Over 60 genes are known to cause CH, many of which were first discovered in mice. Nonetheless, 81% of CH patients still lack a molecular diagnosis, which would be invaluable for planning treatment and predicting future risk. We propose detailed phenotyping of existing embryonic lethal knockout mice with known genetic defects that result in hypothalamic and/or pituitary malformations. This will expand the molecular diagnoses for CH and associated midline deficiencies in humans and increase our understanding of organogenesis of these critical tissues. We identified a prioritized set of 18 embryonic lethal or sub-viable mouse lines with obvious malformations in the hypothalamus and/or pituitary gland. This set of genes are grouped based on function including epigenetic regulators, components of cilia, protein modification, and other novel functional categories. We assembled a team of investigators with expertise in hypothalamic-pituitary development, mouse phenotyping, and bioinformatics. We will conduct deep and thorough phenotyping of the hypothalamus and pituitary gland in the selected IMPC mice. Our pipeline has three steps with appropriate re-prioritization at each stage. First, temporal and spatial expression of the selected genes will be determined in wild type mice, the IMPC strains will be imported, and the dysmorphology will be characterized histologically from mid- gestation to birth. Second, the strains will be assessed for defects in vascularization and specification of hypothalamic neurons and pituitary hormone producing cells using a combination of scRNA-seq and histological methods. Third, a mechanistic understanding of the pathophysiology of the developmental defects will be determined using histology, cell culture assays and/or established tissue-specific cre drivers to test hypotheses developed from scRNA-seq and meta-analyses. This work will establish genotype/phenotype relationships for novel genes that are candidates for the undiagnosed CH patients. Data dissemination will be timely and open, building on our existing mouse pituitary analysis database (mousePAD) and blog, and the IMPC website. Future expansion of our pipeline will add additional lethal or sub-viable IMPC strains with mutations in genes implicated in hypothalamic-pituitary development, but not yet studied. We are poised to make a significant impact on the discovery of genetic defects that affect hypothalamic-pituitary development in mouse and man.