Haploinsufficiency of MBD5 and MBD6 impairs mitochondrial respiration through chromatin-mediated gene regulation [MBD6]

ABSTRACT: Autism spectrum disorder (ASD) is a highly heritable neurodevelopmental disorder, yet the molecular mechanisms linking ASD-associated genes to cellular dysfunction remain incompletely understood. Among methyl-CpG binding domain (MBD) proteins, MBD5 and MBD6 are recurrently disrupted in individuals with ASD, but their functional roles in neuronal cells are poorly defined. Here, we investigated the consequences of MBD5 and MBD6 haploinsufficiency using human neuroblastoma SH-SY5Y cells. We established MBD5- and MBD6-heterozygous SH-SY5Y cell lines by genome editing and performed genome-wide transcriptome analysis. Microarray profiling revealed widespread transcriptional dysregulation, with predominant gene upregulation, suggesting that both proteins function mainly as transcriptional repressors. Notably, a shared subset of downregulated genes included multiple mitochondrial-related genes, such as COX17, COX4I2, DHRS2, MCUB, and PDK1. Quantitative real-time PCR validated these expression changes. Analysis of public ChIP-seq datasets further demonstrated co-localization of MBD5, MBD6, and components of the BAP1 complex at the COX17 promoter, suggesting direct regulation through a chromatin-associated mechanism. Functionally, MBD5 and MBD6 haploinsufficiency impaired mitochondrial respiration, as evidenced by reduced basal and ATP-linked oxygen consumption rates without changes in mitochondrial content. Consistently, heterozygous cells showed severe growth defects under galactose conditions and a compensatory shift toward glycolytic metabolism. Together, these findings identify a previously unrecognized chromatin–mitochondria regulatory axis linking MBD5 and MBD6 haploinsufficiency to mitochondrial dysfunction, providing mechanistic insight into ASD pathogenesis.

ORGANISM(S): Homo sapiens

PROVIDER: GSE314093 | GEO | 2026/01/19

REPOSITORIES: GEO