Amyloid beta precursor protein binding family B member 1

APBB1 (amyloid beta precursor protein binding family B member 1) is a transcription coregulator that functions as both a coactivator and corepressor, with dual roles in transcriptional control and DNA damage response (UniProt: O00213). The protein forms transcriptionally active complexes with the APP intracellular domain derived from gamma-secretase cleavage, and plays a central role in nuclear translocation and apoptosis induction following DNA damage. APBB1 also contributes to hippocampal neurite branching and neuromuscular junction formation, supporting spatial memory function.

APBB1 is involved in chromatin remodeling through recognition of phosphorylated histone H2AX at double-strand breaks and recruitment of pro-apoptotic factors, as well as histone acetylation via interaction with chromatin-modifying enzymes (UniProt: O00213). The protein associates with transcriptional repressor complexes containing TSHZ3, SET, and HDAC factors to inhibit caspase-4 expression.

In Alzheimer's disease, APBB1 is downregulated in post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics), with a mean log2 fold-change of −0.42 across subcellular fractions in TMT-labeled mass spectrometry analysis. This reduction may contribute to altered APP-mediated signaling and transcriptional dysregulation in AD pathology.