Abstract
The dopamine D2 receptor (D2R) plays a crucial role in the regulation of diverse key physiological functions, including motor control, reward, learning, and memory. This receptor is present in vivo in two isoforms, D2L and D2S, generated from the same gene by alternative pre-mRNA splicing. Each isoform has a specific role in vivo, underlining the importance of a strict control of its synthesis, yet the molecular mechanism modulating alternative D2R pre-mRNA splicing has not been completely elucidated. Here, we identify heterogeneous nuclear ribonucleoprotein M (hnRNP M) as a key molecule controlling D2R splicing. We show that binding of hnRNP M to exon 6 inhibited the inclusion of this exon in the mRNA. Importantly, the splicing factor Nova-1 counteracted hnRNP M effects on D2R pre-mRNA splicing. Indeed, mutations of the putative Nova-1-binding site on exon 6 disrupted Nova-1 RNA assembly and diminished the inhibitory effect of Nova-1 on hnRNP M-dependent exon 6 exclusion. These results identify Nova-1 and hnRNP M as D2R pre-mRNA-binding proteins and show their antagonistic role in the alternative splicing of D2R pre-mRNA.
Highlights
Ventions for the treatment of Parkinson disease, schizophrenia, depression, and pituitary tumors
We identify heterogeneous nuclear ribonucleoprotein M and neuro-oncological ventral antigen-1 (Nova-1) as splicing regulators that bind to D2 receptor (D2R) exon 6 and show their functional relevance to the molecular mechanism generating the D2L and D2S isoforms of the D2R gene
HnRNP M Directly Interacts with D2R Exon 6—To investigate cis-acting elements and trans-acting factors that regulate alternative D2R pre-mRNA splicing, we prepared two RNA probes by subdividing D2R exon 6 (E6) into two fragments (E6-1 and E6-2) (Fig. 1A)
Summary
HnRNP M and Nova-1 regulate alternative D2R pre-mRNA splicing in an antagonistic manner
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