The Functional Studies Of Lrp4 In Zebrafish

LRP4(Low density lipoprotein receptor related protein 4),also called MEGF7(multiple epidermal growth factor-like domain 7),is an important member of the low density lipoprotein receptor family,including the extracellular domain,transmembrane region and intracellular region.The extracellular domain is rich in multiple EGF like repeats and LDLR repeats.LRP4 is highly conserved in vertebrate evolution,the researches on which were mainly in the development of bone and muscle.But,so far,the overall regulatory mechanism is not clear,especially in the skeleton.But current researches have shown that LRP4 as a receptor involved in the regulation of classical Wnt signaling pathway in bone development.CLSS(Cenani-Lenz Syndactyly Syndrome,CLS Syndrome)is not only an autosomal recessive genetic disease,but also a congenital disorder of skeletal development.The typical feature of CLSS patients is the fusion of the fingers or toes,the shortening and fusion of the radial ulna,the fusion of the metacarpal and the digital bone,usually accompanied by renal hypoplasia.Recent studies have shown that mutations in the LRP4 was the main cause of CLSS.We isolated a novel missense mutation c.1117C>T in LRP4 from a CLSS family members of the patient through sequencing,which caused agrin to tryptophan in LRP4.To further investigate the role of LRP4 in the development of bone and kidney,we use zebrafish as an animal model for lrp4 by using the technology of ‘knockdown'.We found lrp4 morphants can partially mimic the CLSS.lrp4 morphants have vacuolation in central fin,as well as morphological defects of renal,especially renal tubular and glomerular.By q RT-PCR and in situ hybridization,we verified that lrp4 was not only related to Wnt pathway,but also involved in the Notch pathway during regulation of bone development.This study shows that LRP4 plays a key role in the process of vertebrate skeletal and renal development,which will laid the foundation for the construction of signal network about LRP4 in skeletal development and renal development,and lay a solid foundation for the study and diagnosis and treatment of bone disease.