Human Molecular Genetics Advance Access originally published online on September 22, 2009
Human Molecular Genetics 2009 18(23):4565-4575; doi:10.1093/hmg/ddp422
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A mouse model for Meckel syndrome reveals Mks1 is required for ciliogenesis and Hedgehog signaling
1 Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA, 2 Genetics Department, Yale University School of Medicine, New Haven, CT 06510, USA and 3 Department of Pediatrics, University of Colorado Health Sciences Center, Aurora, CO 80045, USA
* To whom correspondence should be addressed at: Genetics Department, Yale University School of Medicine, PO Box 208005, New Haven, CT 06520, USA. Email: scott.weatherbee{at}yale.edu
Received July 17, 2009; Revised August 18, 2009; Accepted August 28, 2009
Meckel syndrome (MKS) is a rare autosomal recessive disease causing perinatal lethality associated with a complex syndrome that includes occipital meningoencephalocele, hepatic biliary ductal plate malformation, postaxial polydactyly and polycystic kidneys. The gene mutated in type 1 MKS encodes a protein associated with the base of the cilium in vertebrates and nematodes. However, shRNA knockdown studies in cell culture have reported conflicting results on the role of Mks1 in ciliogenesis. Here we show that loss of function of mouse Mks1 results in an accurate model of human MKS, with structural abnormalities in the neural tube, biliary duct, limb patterning, bone development and the kidney that mirror the human syndrome. In contrast to cell culture studies, loss of Mks1 in vivo does not interfere with apical localization of epithelial basal bodies but rather leads to defective cilia formation in most, but not all, tissues. Analysis of patterning in the neural tube and the limb demonstrates altered Hedgehog (Hh) pathway signaling underlies some MKS defects, although both tissues show an expansion of the domain of response to Shh signaling, unlike the phenotypes seen in other mutants with cilia loss. Other defects in the skull, lung, rib cage and long bones are likely to be the result of the disruption of Hh signaling, and the basis of defects in the liver and kidney require further analysis. Thus the disruption of Hh signaling can explain many, but not all, of the defects caused by loss of Mks1.
The authors wish it to be known that, in their opinion, the last two authors contributed equally to this work.