title: Expression of the integrin subunit alpha8 in murine lung development.
abstract: The complex interplay between cells and extracellular matrix (ECM) proteins is critical for lung development. Integrins are key modulators of this interaction. The integrin subunit alpha 8 associates with the beta(1)-subunit to form an RGD-binding integrin. We previously showed that, in adult lung, alpha 8 is expressed in contractile interstitial cells and smooth muscle cells and is upregulated in lung injury. To gain insight into the function of alpha 8 during lung development, we examined the spatiotemporal expression of alpha 8 throughout murine lung development. We compared the distribution of alpha 8 with alpha-smooth muscle actin (alpha SMA), fibronectin (alpha 8 ligand), and cytokeratin. alpha 8 co-localized with alpha SMA and fibronectin in the peribronchial and perivascular regions. In all stages, alpha 8 immunoreactivity was detected diffusely in the mesenchyme except for cells surrounding distal, newly forming airways. alpha 8, alpha SMA, and fibronectin co-localized at tips of secondary septae in the alveolar stage. We conclude that alpha 8 is marker for lung mesenchymal cells starting early in development. alpha 8 is also a marker for smooth muscle cells, expressed as early as alpha SMA. Co-localization of alpha 8 with fibronectin suggests a role in branching morphogenesis. Furthermore, alpha 8 may participate in secondary septation by modulating signals from the extracellular matrix to alveolar myofibroblasts.
mesh_terms: D000199:Actins / Q000032:analysis / Q000096:biosynthesis; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D005260:Female; D005353:Fibronectins / Q000032:analysis / Q000096:biosynthesis; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D039001:Integrin alpha Chains / Q000096:biosynthesis*; D007633:Keratins / Q000032:analysis / Q000096:biosynthesis; D008168:Lung / Q000196:embryology* / Q000378:metabolism*; D008297:Male; D008648:Mesoderm / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009130:Muscle, Smooth / Q000737:chemistry / Q000254:growth & development; D014018:Tissue Distribution
chemical_list: D000199:Actins; D005353:Fibronectins; D039001:Integrin alpha Chains; C093856:integrin alpha8; D007633:Keratins