Cellular Interactions with Extracellular Matrix During Development and in Muscle Disease

• Main Author: Tiger, Carl-Fredrik
• Format: Doctoral Thesis
• Language: English
• Published: Uppsala universitet, Institutionen för cell- och molekylärbiologi 2002
• Subjects: Cell and molecular biology; integrin; laminin; collagen; muscle; tendon; skeleton; mouse; human; development; Cell- och molekylärbiologi
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-2007; http://nbn-resolving.de/urn:isbn:91-554-5328-7

The formation and maintenance of tissues in multicellular animals are crucially dependent on cellular interactions with the extracellular matrix (ECM). Two different studies on such interactions are presented herein. Studies on expression of laminins in normal and dystrophic skeletal muscle, clarified a much debated issue regarding discrepancies seen for laminin α1-chain expression between human and mouse tissues. Lack of laminin α1-chain expression was verified in both mouse and human skeletal muscle. Furthermore, the earlier discrepancies seen for laminin α1-chain expression was explained by showing that an antibody-reagent, commonly used in human studies, recognised the laminin α5-chain rather than the laminin α1-chain The integrin α11-chain (forming α11β1 integrin) is the latest addition to the integrin receptor family, and belongs to the I domain-containing group of integrin α-chains. Previous studies had shown that α11β1 is a collagen receptor. In the present study, the in vitro and in vivo functions of the α11-chain were further characterised. Distribution studies on embryonic human and mouse tissues showed that the α11-chain was expressed on mesenchymal cells in the developing tendon, perichondrium, intervertebral disc, and cornea. The interactions of α11β1 integrin with collagen type I and IV were studied in vitro. The α11β1 bound to these collagens in a manner similar to integrin α2β1 (with collagen type I being the preferred ligand for α11β1). Furthermore, α11β1 was shown to mediate migration on collagen type I coated surfaces, and to mediate contraction of collagen type I gels. The in vivo functions of the α11-chain were investigated by the generation of integrin α11-chain null-mice, using gene targeted disruption of the itga11 in embryonic stem cells. Two independent lines of mice lacking α11 protein were generated. Phenotypic analysis of these mice indicated a role for α11β1 in the formation of the musculoskeletal system.