Pathogenicity of p.Phe147del in RET in familial Hirschsprung's disease.

OBJECTIVE: The study aimed to explore the pathogenicity of RET p.Phe147del in a Hirschsprung'irschspru (HSCR) family and facilitate the deeper understanding of HSCR families.

METHODS: Whole-exome sequencing (WES) was performed to decipher a HSCR family. We used a "GlycoEP" tool to analyze RET protein glycosylation. A series of molecular biological approaches including mutated plasmid construction, cell transfection, polymerase chain reaction, immunofluorescence and immunoblotting were introduced to determine the mutation status and altered expression of RET as well as its related genes or proteins. MG132 was applied to analyze the mechanism of mutated RET.

RESULTS: WES and Sanger results revealed that p.Phe147del in-frame mutation (IM) was a potential pathogenetic factor for familial HSCR. Moreover, the IM led to disrupted N-glycosylation of RET accompanied with protein structural change, resulting in the decreased transcriptional and protein level of RET, CCND1, VEGF and BCL2, and the decreased protein level of phosphorylated ERK and STAT3. Further studies revealed that the IM-evoked RET decline was reversed by inhibiting proteosome in a dose dependent manner, thus suggesting that the decrease in intracellular RET protein levels interrupted the transportation of RET protein from the cytoplasm to the cell surface.

CONCLUSION: The newly found p.Phe147del IM of RET is pathogenic to familial HSCR and it disrupts RET structure and abundance via the proteasome pathway, representing evidence for the early prevention, clinical diagnosis and treatment of HSCR.