Katherine Mcdonald

Katherine Mcdonald

PI: Maureen Gannon, PhD , Department of Medicine

Pdx1/Oc1 Double Heterozygosity Affects Regulatory Transcription Factor Expression Important for β-cell Development

Pdx1 (Pancreatic and duodenal homeobox 1) and Oc1 (Onecut 1; aka Hepatic nuclear factor 6) are transcription factors co-expressed in multipotent pancreatic progenitor cells. Pdx1 is necessary for pancreas development, endocrine specification and differentiation, and postnatal β-cell function. Oc1 is also necessary for regulating transcription factors during pancreas development and activates the definitive pro-endocrine transcription factor Neurogenin 3. Although these factors have divergent expression patterns in the endocrine lineage, we had previously hypothesized that proper levels of both factors were necessary for proper endocrine development. RNA-Sequencing experiments in mice at embryonic day (e)15.5 showed that mice with combined Pdx1 and Oc1 heterozygosity have significant impairments in gene expression of many other transcription factors involved in β-cell specification and differentiation. This is not seen in Pdx1 or Oc1 single heterozygotes. However, RNA-Sequencing only quantifies levels of mRNA expression and does not explain the how gene expression is altered at a cellular level. Therefore, the mechanism by which double heterozygosity causes β-cell dysfunction remains unknown. By utilizing immunofluorescent labeling of pancreatic tissue sections from e15.5 mice, I am investigating whether double heterozygotes have reduced protein levels of these transcription factors due to a reduction in expression on a per cell basis or a reduction in the number of cells expressing the factors. It is too early to report results or conclusions. However, by investigating these patterns of gene expression, β-cell development can be better understood and aide in the search for a way to reverse diabetes by regenerating or rescuing β cells.