Alteration of protein-protein interactions of congenital cataract crystallin mutants
INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE
Authors: Fu, L; Liang, JJN
Abstract
PURPOSE. A recent study demonstrated the presence of protein-protein interactions among lens crystallins in a mammalian cell two-hybrid system assay and speculated about the significance of these interactions for protein solubility and lens transparency. The current study extends those findings to the following crystallin genes involved in some congenital cataracts: CRYAA (R116C), CRYAB (R120G), and CRYGC (T5P). METHODS. A mammalian two-hybrid system was used to assay the protein-protein interactions. Congenital cataract crystallin genes were cloned and fused into the two-hybrid system vectors (target and prey proteins). Together, with the third vector containing a reporter gene, chloramphenicol acetyltransferase (CAT), they were cotransfected into human HeLa cells. The presence of protein-protein interactions and the strength of these interactions were assayed by CAT ELISA. RESULTS. The pattern of changes in protein-protein interactions of those congenital cataract gene products with the three major crystallins, alphaA- or alphaB-, betaB2-, and gammaC-crystallins, differed. For the T5P gammaC-crystallin, most of the interactions were decreased; for the R116C alphaA-crystallin, the interactions with betaB2-and gammaC-crystallin decreased and those with alphaB-crystallin and heat-shock protein (Hsp)27 increased; and for the R120G alphaB-crystallin, the interactions with alphaA- and alphaB-crystallin decreased, but those with betaB2- and gammaC-crystallin increased slightly. An attempt was made to interpret the results on the basis of conformational change and disruption of dimeric interaction involving beta-strands. CONCLUSIONS. The results clearly indicate that crystallin mutations involved in congenital cataracts altered protein-protein interactions, which may contribute to decreased protein solubility and formation of cataract.
A novel missense mutation of CRYBB1 causes congenital cataract in a Chinese family
EUROPEAN JOURNAL OF OPHTHALMOLOGY
Authors: Ji, Yanan; Zhao, Xiangyu; Zhang, Juanmei; Zhang, Dan; Tian, Chunliu; Zhang, Linlin; Zhao, Youcai; Zhao, Jun
Abstract
Objective of the study: To identify the pathogenic gene and mutation site of a Chinese family with congenital cataract. Methods: Eight family members and 100 controls were employed, and targeted exome sequencing was used to identify the genetically pathogenic factor of the proband. Results: Targeted next-generation sequencing identified a novel missense mutation c.209A>C (p.Q70P) of CRYBB1 gene in the family. Sanger sequencing results showed that this heterozygous mutation was a causative mutation, which was not found in unaffected family members and healthy controls. Bioinformatics predicts that the effect of this mutation on protein function is probably harmful. Conclusion: We demonstrate that c.209A>C of CRYBB1 gene is a pathogenic mutation in the family of congenital nuclear cataract in this study. This is the first report that this mutation leads to congenital nuclear cataract, which broadens the mutation spectrum of CRYBB1 gene in congenital nuclear cataract.