title: Dystroglycan is essential for early embryonic development: disruption of Reichert's membrane in Dag1-null mice.
abstract: Dystroglycan is a central component of the dystrophin-glycoprotein complex (DGC), a protein assembly that plays a critical role in a variety of muscular dystrophies. In order to better understand the function of dystroglycan in development and disease, we have generated a null allele of dystroglycan (Dag1neo2) in mice. Heterozygous Dag1neo2 mice are viable and fertile. In contrast, homozygous Dag1neo2 embryos exhibit gross developmental abnormalities beginning around 6.5 days of gestation. Analysis of the mutant phenotype indicates that an early defect in the development of homozygous Dag1neo2 embryos is a disruption of Reichert's membrane, an extra-embryonic basement membrane. Consistent with the functional defects observed in Reichert's membrane, dystroglycan protein is localized in apposition to this structure in normal egg cylinder stage embryos. We also show that the localization of two critical structural elements of Reichert's membrane--laminin and collagen IV--are specifically disrupted in the homozygous Dag1neo2 embryos. Taken together, the data indicate that dystroglycan is required for the development of Reichert's membrane. Furthermore, these results suggest that disruption of basement membrane organization might be a common feature of muscular dystrophies linked to the DGC.
authors.affiliation: Department of Obstetrics and Gynecology, University of Iowa Hospitals and Clinics, Iowa City 52242, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Williamson
authors.forename: M D
authors.initials: MD
authors.lastname: Henry
authors.forename: K J
authors.initials: KJ
authors.lastname: Daniels
authors.forename: R F
authors.initials: RF
authors.lastname: Hrstka
authors.forename: J C
authors.initials: JC
authors.lastname: Lee
authors.forename: Y
authors.initials: Y
authors.lastname: Sunada
authors.forename: O
authors.initials: O
authors.lastname: Ibraghimov-Beskrovnaya
authors.forename: K P
authors.initials: KP
authors.lastname: Campbell
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001485:Basement Membrane / Q000737:chemistry / Q000196:embryology* / Q000378:metabolism; D003094:Collagen / Q000032:analysis; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000502:physiology*; D049030:Dystroglycans; D005314:Embryonic and Fetal Development / Q000502:physiology*; D017353:Gene Deletion; D015870:Gene Expression; D006801:Humans; D007797:Laminin / Q000032:analysis; D008562:Membrane Glycoproteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D011817:Rabbits; D017386:Sequence Homology, Amino Acid
chemical_list: D003598:Cytoskeletal Proteins; C483081:DAG1 protein, human; D007797:Laminin; D008562:Membrane Glycoproteins; D049030:Dystroglycans; D003094:Collagen