Mutations on a novel brain-specific isoform of PGC1α leads to extensive upregulation of neurotransmitter-related genes and sexually dimorphic motor deficits in mice

The peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC1) is known as a transcriptional co-activator in peripheral tissues but its function in the brain remains poorly understood. Various brain-specific Pgc1 isoforms have been reported in mice and humans, including transcripts derived from a novel promoter about [~]580 Kb upstream from the reference gene. These isoforms incorporate repetitive sequences from the simple sequence repeat (SSR) and short interspersed nuclear element (SINE) classes and are predicted to give rise to proteins with distinct amino-termini. In this study, we show that a SINE-containing isoform is the predominant form of Pgc1 expressed in neurons. We then generated a mouse carrying a mutation within the SINE to study its functional role in the brain. By combining genomics, biochemical and behavioural approaches, we show that this mutation leads to impaired motor coordination in females, but not male mice, associated with the upregulation of hundreds of cerebellar genes. Moreover, our analysis suggests that known nuclear receptors interact with this isoform of PGC1 in the brain to carry out the female transcriptional program. These data expand our knowledge on the role of Pgc1 in the brain and help explain its conflicting roles in neurological disease and behavioural outcomes.