ZBTB7B is a Master Regulator of Salivary Acinar Cell Function

Salivary glands exhibit transcriptional programs that distinguish them from other tissues, yet the upstream regulatory logic underlying these programs is not well defined. To identify transcription factors (TFs) that structure salivary identity, we generated RNA-seq and ATAC-seq from human major and minor salivary glands and inferred TF[->]TF regulatory edges from high-confidence chromatin footprints. ZBTB7B emerged as the most connected regulator across salivary samples. To locate regulatory regions associated with salivary-specific transcription, we trained hidden Markov models (HMMs) on chromatin accessibility across 4 Mbp windows surrounding salivary-specific and non-salivary-specific transcription start sites. The resulting chromatin states distinguished promoter-proximal openness from distal enhancer activity and identified salivary-specific enhancers enriched for ZBTB7B motifs. These enhancer states correlated strongly with expression of salivary genes, including AQP5, indicating that distal regulation contributes substantially to salivary transcriptional specificity. To assess the consequences of losing Zbtb7b, we performed single-cell RNA-seq and spatial transcriptomics on submandibular and parotid glands from Zbtb7b knockout mice. Knockout mice exhibited reduced salivary flow, shifts in acinar cell proportions, and the emergence of a neonate-like acinar population characterized by loss of canonical secreted proteins and increased expression of MHC class I genes. These transcriptional and cellular changes occurred despite preserved gland architecture, suggesting that Zbtb7b stabilizes adult acinar identity rather than supporting structural maintenance. Together, these data identify ZBTB7B as a master regulator of salivary transcriptional networks, acting through both promoter-proximal and enhancer-level mechanisms, and demonstrate that loss of Zbtb7b disrupts acinar identity and impairs salivary function.