PVDF membranes were blocked in laminin-binding buffer (LBB; 10 mmtriethanolamine, 140 mmNaCl, 1 mmMgCl2, and 1 mmCaCl2, pH 7.6) containing 5% non-fat dry milk, incubated overnight at 4C in LBB containing 7.5 nmmouse EHS (EngelbrethHolmSwarm) laminin-1 (Collaborative Biomedical Products), washed, and labeled with an antibody to laminin. defects in posttranslational processing or mutations of the dystroglycan gene itself may underlie cases in which no causative mutation has been found. Keywords:WalkerWarburg syndrome, congenital muscular dystrophy, lissencephaly, hydrocephalus, microphthalmia, dystroglycan == Introduction == WalkerWarburg syndrome (WWS) is usually clinically defined by a spectrum of brain Erlotinib HCl and vision malformations and congenital muscular dystrophy. Characteristic features of WWS include type II (cobblestone) lissencephaly, hydrocephalus, pontocerebellar hypoplasia, microphthalmia, and retinal dysplasia and nonattachment (Dobyns et al., 1989;Muntoni and Voit, 2004). Muscle-eye-brain disease (MEB) and Fukuyama-type congenital muscular dystrophy (FCMD) have similar CNS involvement but less severe clinical presentations and longer survival than WWS, which is usually lethal during the first year of life (Muntoni and Voit, 2004). Although the majority of WWS cases have unknown etiologies, 20% of WWS cases are linked to mutations in proteinO-mannosyltransferase 1 (POMT1) (Beltrn-Valero de Bernab et al., 2002). POMT1 associates with POMT2, Erlotinib HCl and the heterodimer Rabbit polyclonal to IFIT5 is usually capable of transferring anO-mannosyl glycan to the -subunit of dystroglycan (Manya et al., 2004). Dystroglycan is composed of and subunits that are encoded by a single gene,DAG1, on chromosome 3p21 in humans (Ibraghimov-Beskrovnaya et al., 1993) and on chromosome 9 in mice (Grecki et al., 1994). The extracellular subunit and the transmembrane subunit are posttranslationally cleaved and noncovalently associated (Ibraghimov-Beskrovnaya et al., 1993;Jayasinha et al., 2003).O-Glycosylation of the -subunit (-dystroglycan) is essential for its high-affinity binding to both laminin and the laminin-like globular domains of agrin, perlecan, and neurexin (Ervasti and Campbell, 1993;Gee et al., 1994;Peng et al., 1998;Sugita et al., 2001). The dystroglycan null mutation is usually lethal in mice at approximately embryonic day 6.5 (E6.5) (Williamson et al., 1997). Breaches of Reichert’s membrane in the parietal wall of the dystroglycan null yolk sac suggested that the cause of lethality may be a loss of separation between the maternal and embryonic circulations. Deletion ofPomt1orFcmd, which encodes the putative glycosyltransferase fukutin, also results in embryonic lethality in Erlotinib HCl mice as well as loss of -dystroglycan glycosylation and defects in the integrity of Reichert’s membrane (Willer et al., 2004;Kurahashi et al., 2005), suggesting that posttranslational modification by POMT1 and fukutin is necessary for dystroglycan function during early mouse embryogenesis. Reichert’s membrane is an extraembryonic structure that is specific to rodent development, and it is not known whether dystroglycan is necessary for survival of the human embryo. However, anin vitrostudy reported apoptosis and degeneration in dystroglycan null mouse embryoid body (Li et al., 2002), suggesting that dystroglycan may be necessary for survival of the mouse embryo. Here we statement that dystroglycan expression and ligand-binding activity are disrupted in the WWS brain, and that the phenotype of mice with epiblast-specific loss of dystroglycan (MORE-DG null) broadly resembles the clinical spectrum of the human disease. In the MORE-DG null mice, breaches of basement membranes coincide with malformations of the brain and the anterior and posterior chambers of the eye, demonstrating an important role for dystroglycan in their morphogenesis. Together, these findings indicate a central role for dystroglycan in the pathogenic mechanism of the human disease, including the cases for which no causative mutation has been found. == Materials and Methods == == == == == == Mutation analysis. == Genomic DNA was isolated from human skeletal muscle mass using standard extraction protocols. The complete coding regions, including intron/exon boundaries, ofDAG1,POMT1,POMT2,O-mannose -1,2-N-acetylglucosaminyltransferase (POMGnT1), Fukutin-related protein (FKRP),fukutin, andLARGEwere amplified by PCR (primers and sequences are available on request). The amplicons generated were purified and directly sequenced with the BigDye terminator cycle sequencing kit version 3.1 (Applied Biosystems). Sequences were analyzed on an ABI3130xl capillary Sequencer (Applied Biosystems).POMT1andLARGEwere sequenced by PreventionGenetics. == Generation of mice. == Generation of the floxed-dystroglycan and MORE-DG null mouse strains has been explained previously.