In muscular tissues, alpha7beta1 is the major integrin receptor for laminins, which are represented by isoforms laminin 2 and 4 (basal laminae of skeletal and cardiac muscle cells) 8 and 10 (smooth muscle cell basal laminae). The absence of alpha7 integrin chain leads to the onset of skeletal muscular dystrophies (Mayer U et al, Nature Genet 1997, 17 ,318), and cardiac hypertrophy (Ortolani et al, in press). In alpha 7 integrin chain deficient mice, we previously observed different degrees of ultrastructural alteration between viscera wall smooth muscle cells of those in vascular walls. Since moderate up-regulation of alpha 5 integrin chain was described for alpha 7 deficient skeletal muscle ( Nawrotzki R et al, Hum Mol Genet. 2013,12,483), here compensatory overexpression was investigated of other alpha integrin chains and laminins in alpha 7 deficient mice, concerning smooth muscle cells of muscularis externa of oesophagus, stomach, ileus, colon, bladder, uterus as well as those in tunica media of vessels of the heart, different skeletal muscles, and viscera walls as above. No differences appeared for alpha 5 and alpha 6 integrin chain distribution pattern in both control and K.O. mice, whereas remarkable increase in alpha 3 integrin chain was apparent in K.O. smooth muscle cells versus control ones, more evident in viscera walls than in vascular ones, consistently with the weaker damage observed. Concerning the distribution of laminin chains, no differences was detected by comparing w/t and K.O. mice.
