Core histone macro-H2A.1

Core histone macro-H2A.1 (MACROH2A1) is a variant histone H2A protein that replaces conventional H2A in select nucleosomes. It functions primarily as a transcriptional repressor by inhibiting transcription factor binding—including NF-κB—and interfering with SWI/SNF chromatin remodeling complexes (UniProt: O75367). The protein also recruits class I histone deacetylases, maintaining hypoacetylated chromatin states. Isoform-specific functions include poly-ADP-ribose binding and regulation of NAD+ metabolism, with implications for redox homeostasis and mitochondrial respiration.

MACROH2A1 is a core component of chromatin structure and plays roles in DNA accessibility, transcriptional regulation, DNA repair, and X chromosome inactivation. The protein participates in NAD+-dependent cellular signaling and regulates expression of genes involved in oxidative stress responses, such as SOD3 (UniProt: O75367).

MACROH2A1 shows elevated expression in Alzheimer's Disease, with a mean log2 fold-change of +0.69 in post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics). This upregulation was detected across human brain subcellular fractions using TMT-labeled quantitative proteomics, suggesting potential involvement in AD-associated chromatin remodeling or NAD+ metabolism dysfunction.