Epigenetic Control of Adaptive or Homeostatic Splicing of Alternative Exons and Prolactin Gene Expression During Interval-Training Activities of Pituitary Cells

Interval-training activities induce adaptive cellular changes without altering their fundamental identity, but the precise underlying molecular mechanisms are not fully understood. In this study, we demonstrate that interval-training depolarization (ITD) of pituitary cells triggers distinct adaptive or homeostatic splicing responses of alternative exons. This occurs while preserving the steady-state expression of the Prolactin and other hormone genes. The nature of these splicing responses depends on the exon’s DNA methylation status, the methyl-C-binding protein MeCP2 and its associated CA-rich motif-binding hnRNP L. Interestingly, the steady expression of the Prolactin gene is also reliant on MeCP2, whose disruption during ITD leads to exacerbated overexpression and multi-exon aberrant splicing of the hormone gene transcripts, similar to the observed hyperprolactinemia or activity-dependent aberrant splicing in Rett Syndrome. Therefore, depending on how many times cells are stimulated, exons may exhibit different splicing responses to cell activities. During the ITD, epigenetic control is crucial for both adaptive or homeostatic splicing and the steady expression of the Prolactin hormone gene. Disruption in this regulation may have significant implications for the development of progressive diseases.