A new mechanism underlying mitochondrial dysfunction in schizophrenia – attenuated mRNA transport of the complex I subunit NDUFV2 by its pseudogene NDUFV2P1

While schizophrenia (SZ) etiology remains unclear, accumulating evidence implicates mitochondrial dysfunction, particularly complex-I of the respiratory chain and its essential free-electron scavenger subunit, NDUFV2, as a contributor to neuronal and behavioral impairments observed in SZ. Our recent studies suggest a potential role for the NDUFV2 pseudogene (NDUFV2P1) in NDUFV2 deficits. Here, we describe a mechanism by which NDUFV2P1 negatively controls NDUFV2 mRNA transport and its protein levels in SZ-derived lymphocyte cell lines (SZ-LCLs). We found increased NDUFV2P1 transcript levels in SZ frontal cortex postmortem specimens (SZ-FCX) and across all studied SZ-LCLs subcellular fractions. However, NDUFV2 levels were reduced in SZ-FCX and in all cell compartments, except for the nucleus, as compared to healthy subjects-derived LCLs (CTL-LCLs), suggesting its impaired nuclear export. Concomitantly, we observed increased NDUFV2P1, yet decreased NDUFV2 mRNA binding to NXF1, a key player in nuclear mRNA export. Overexpression of NDUFV2P1 in CTL-LCLs mimicked the SZ-state, reducing NDUFV2 levels and its binding to NXF1. The interactome of both mRNAs revealed an opposite binding profile for most RNA-binding proteins (RBPs) in SZ-LCLs compared to CTL-LCLs. Pathway enrichment analysis of the differentially bound RBPs to both transcripts revealed additional potential interference sites for NDUFV2 and NDUFV2P1, including ribosomal-, spliceosome-, and RNA transport-related RBPs. This study uncovers a new mechanism in which NDUFV2P1 interferes with RBPs involved in regulating NDUFV2 transport from the nucleus to mitochondrial-bound ribosomes. While further validation is necessary to substantiate this mechanism, the findings highlight NDUFV2P1 potential as a means for regulating mitochondrial function and consequently energy metabolism in SZ.