Bhlha15
Developmental stage
First observed at 10.5 dpc in the primitive gut and in the developing lung bud. Expression in the gut persists through 16.5 dpc and remains restricted primarily to the epithelial lining of the esophagus, stomach and intestine. Expression in the lung is detected in the bronchial epithelium at 14.5 dpc and at 15.5 dpc. Expressed specifically in acinar cells during pancreatic development. Detected in skeletal muscle tissues beginning at 12.5 dpc, persisting throughout all embryonic stages examined although, in older embryos expression becomes severely reduced.
Domain
Lacks a classic transcription activation domain and instead possesses an N-terminal region capable of inhibiting heterologous activators.
Function
Plays a role in controlling the transcriptional activity of MyoD, ensuring that expanding myoblast populations remain undifferentiated (PubMed:17612490). Repression may occur through muscle-specific E-box occupancy by homodimers. May also negatively regulate bHLH-mediated transcription through an N-terminal repressor domain. Serves as a key regulator of acinar cell function, stability, and identity. Also required for normal organelle localization in exocrine cells and for mitochondrial calcium ion transport. May function as a unique regulator of gene expression in several different embryonic and postnatal cell lineages. Binds to the E-box consensus sequence 5'-CANNTG-3'.
Tissue Specificity
Expressed in pancreatic tissue only in acinar cells. There is a complete absence of expression in intra- or interlobular pancreatic ducts and in all islet cells.
Cellular localization
- Nucleus
Alternative names
Bhlhb8, Mist1, Bhlha15, Class A basic helix-loop-helix protein 15, bHLHa15, Class B basic helix-loop-helix protein 8, bHLHb8, MIST-1