It has been discovered that Collagen III the encoded protein of
It has been discovered that Collagen III the encoded protein of the type IV Ehlers-Danlos Syndrome (EDS) gene is one of the major constituents of the pial basement membrane (BM) and serves as the ligand for GPR56. morbidity. Cobblestone lissencephaly is one common form of cortical dyslamination in which neurons migrate beyond the breached pial BM and form ectopias on the surface of the brain . Cobblestone lissencephaly is seen in three types of human congenital muscular dystrophy syndromes; Walker -Warburg syndrome (WWS) Fukuyama-type muscular dystrophy (FCMD) and muscle-eye-brain disease (MEB). WWS is the most severe form of congenital muscular dystrophy with the vast majority of patients dying in utero or in early infancy. The genetic cause for MEB FCMD and some WWS cases is aberrant glycosylation of α-dystroglycan a receptor for laminin . GPR56 is a member of the adhesion G protein-coupled receptor (GPCR) family. Mutations in cause a specific human brain malformation called bilateral frontoparietal polymicrogyria (BFPP) -. The magnetic resonance images of BFPP brains revealed a thickened cerebral cortex with coarse gyri shallow sulci and a “scalloped” appearance at the grey-white matter junction – much like the radiological features of other polymicrogyria malformations. Histological analysis of knockout mouse brains and postmortem human BFPP brains revealed the histopathology of BFPP to be cobblestone lissencephaly  . Collagen III is a major collagen found in connective tissues. Mutations in one allele of cause type IV EDS Chlorogenic acid an autosomal dominant connective tissue disorder -. Recently we discovered that collagen III is the ligand of GPR56 . In this paper we carried out a detailed histological analysis of gene is not associated with any obvious defects in mice the effects of deleting both alleles is catastrophic . mice showed severe cortical malformation manifested by the presence of neuronal ectopias on the brain surface (Figure 1 B-I). We next performed immunohistochemistry (IHC) using different layer markers to Rabbit Polyclonal to ACTR3. determine their neuronal composition and from where they first originated. Since over 95% of null mutant mice (Figure 2B D and F) . Figure 1 mice have cortical abnormalities. Figure 2 Cellular composition of deletion we performed a detailed time course study of the occurrence of the breached pial BM and overmigrated neurons. While collagen III was expressed in Chlorogenic acid the meninges and pial BM of mice appeared to Chlorogenic acid be true deletion mutants since collagen III was not present in either the meninges or the pial BM in brains which range from E10.5-E14.5 (Figure 3B D F and H). Oddly enough regardless of the lack of collagen III the pial BM was properly shaped at E10.5 in the mutant mice (Shape 3J). Regional break down of the pial BM with concurrent neuronal overmigration was seen in about half from the E11.5 and everything embryos more Chlorogenic acid than E12.5 in the neocortex. Desk 1 Penetrance of cortical dysplasia in mice. Deleting leads to abnormal connection of radial glial endfeet During regular mind advancement radial glial endfeet put on the pial BM and type an adhesive coating in the pial surface area . Because the appropriate attachment from the radial glial endfeet can be relavent towards the integrity from the pial BM we consequently examined the set up from the endfeet in relationship to the pial BM by double IHC of nestin and laminin. At E10.5 radial glial endfeet were arranged in an orderly fashion along the intact pial BM in the brains of both mice. Loss of collagen III leads to abnormal positioning of both Cajal-Retzius (CR) cells and interneurons There are two major neurons in the marginal zone of the developing neocortex – CR cells and interneurons. CR cells regulate the proper positioning of postmitotic neurons during cortical development by secreting reelin an extracellular matrix (ECM) signaling molecule  . To determine whether CR cells are abnormally located in the developing mice. In order to investigate whether the migration of interneurons is affected by the loss of collagen III we performed an IHC of calbindin in E18.5 brains of wild type and mutant mice. Calbindin+ interneurons were well organized beneath the pial BM in brain (Figure 5C). In contrast we detected calbindin+ interneurons in the ectopias.