Knockdown of Atoh8 in Neurog3-expressing mouse ductal cells mPAC results in altered expression of multiple cell cycle related genes

Atoh8 is a transcription factor of the basic-helix-loop-helix (bHLH) family that is expressed in multiple tissues during embryonic development but whose specific functions remain unknown. The gene encoding Atoh8 is induced by various lineage- determining bHLH transcription factors in cell culture, suggesting a possible common role of this gene in multiple bHLH-driven differentiation programs. In the pancreas, the pro-endocrine bHLH factors Neurogenin3 (Neurog3) and NeuroD1 activate Atoh8 expression. Moreover, Atoh8 is expressed in the embryonic pancreas confirming its participation in the pancreatic transcriptional cascade. This work aims at gaining insight into the molecular function of Atoh8 during the endocrine differentiation program initiated by Neurog3 in the pancreas. To this aim, we have generated a recombinant adenovirus encoding an Atoh8-specific shRNA (Ad-shAtoh8) and used it to down-regulate expression of the Atoh8 gene in Neurog3-expressing pancreatic ductal cells (mPAC), a cellular model of endocrine cell differentiation. Thus, we have compared global changes in gene expression profiles between cells treated with Ad-Neurog3+shControl and cells treated with Ad-Neurog3+shAtoh8 using Affymetrix microarrays. Our results show that Atoh8 silencing significantly affects the expression of 293 genes in Neurog3-expressing mPAC cells. Gene Ontology analysis has revealed cell cycle as the biological function most significantly represented among the modified genes. These results uncover a potential function of Math6 as a regulator of cell cycle progression and provide novel insights into the link between Neurog3 and the regulation of the cell cycle.

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