p63 and Its Target Follistatin Maintain Salivary Gland Stem/Progenitor Cell Function through TGF-β/Activin Signaling.

Multipotent ΔNp63-positive cells maintain all epithelial cell lineages of the embryonic and adult salivary gland (SG). However, the molecular mechanisms by which ΔNp63 regulates stem/progenitor (SP) cell populations in the SG remains elusive. To understand the role of ΔNp63 in directing cell fate choices in this gland, we have generated ΔNp63-deleted adult mice and primary salivary cell cultures to probe alterations in SP cell differentiation and function. In parallel, we have leveraged RNA-seq and ChIP-seq-based characterization of the ΔNp63-driven cistrome and scRNA-seq analysis to molecularly interrogate altered SG cellular identities and differentiation states dependent on ΔNp63. Our studies reveal that ablation of ΔNp63 results in a loss of the SP cell population and skewed differentiation that is mediated by Follistatin-dependent dysregulated TGF-β/Activin signaling. These findings offer new revelations into the SP cell gene regulatory networks that are likely to be relevant for normal or diseased SG states.