Mutations in the U11/U12-65K protein associated with isolated growth hormone deficiency lead to structural destabilization and impaired binding of U12 snRNA.
Antto J NorppaTuuli M KauppalaHarri A HeikkinenBhupendra VermaHideo IwaïMikko J FrilanderPublished in: RNA (New York, N.Y.) (2017)
Mutations in the components of the minor spliceosome underlie several human diseases. A subset of patients with isolated growth hormone deficiency (IGHD) harbors mutations in the RNPC3 gene, which encodes the minor spliceosome-specific U11/U12-65K protein. Although a previous study showed that IGHD patient cells have defects in U12-type intron recognition, the biochemical effects of these mutations on the 65K protein have not been characterized. Here, we show that a proline-to-threonine missense mutation (P474T) and a nonsense mutation (R502X) in the C-terminal RNA recognition motif (C-RRM) of the 65K protein impair the binding of 65K to U12 and U6atac snRNAs. We further show that the nonsense allele is targeted to the nonsense-mediated decay (NMD) pathway, but in an isoform-specific manner, with the nuclear-retained 65K long-3'UTR isoform escaping the NMD pathway. In contrast, the missense P474T mutation leads, in addition to the RNA-binding defect, to a partial defect in the folding of the C-RRM and reduced stability of the full-length protein, thus reducing the formation of U11/U12 di-snRNP complexes. We propose that both the C-RRM folding defect and NMD-mediated decrease in the levels of the U11/U12-65K protein reduce formation of the U12-type intron recognition complex and missplicing of a subset of minor introns leading to pituitary hypoplasia and a subsequent defect in growth hormone secretion.
Keyphrases
- growth hormone
- binding protein
- protein protein
- amino acid
- magnetic resonance
- endothelial cells
- magnetic resonance imaging
- dna methylation
- escherichia coli
- single molecule
- intellectual disability
- copy number
- transcription factor
- dna binding
- staphylococcus aureus
- induced apoptosis
- cell cycle arrest
- biofilm formation
- contrast enhanced
- endoplasmic reticulum stress