DISTINCT ALPHA(7A)BETA(1) AND ALPHA(7B)BETA(1) INTEGRIN EXPRESSION PATTERNS DURING MOUSE DEVELOPMENT - ALPHA(7A) IS RESTRICTED TO SKELETAL-MUSCLE BUT ALPHA(7B) IS EXPRESSED IN STRIATED-MUSCLE, VASCULATURE, ANDNERVOUS-SYSTEM
T. Velling et al., DISTINCT ALPHA(7A)BETA(1) AND ALPHA(7B)BETA(1) INTEGRIN EXPRESSION PATTERNS DURING MOUSE DEVELOPMENT - ALPHA(7A) IS RESTRICTED TO SKELETAL-MUSCLE BUT ALPHA(7B) IS EXPRESSED IN STRIATED-MUSCLE, VASCULATURE, ANDNERVOUS-SYSTEM, Developmental dynamics, 207(4), 1996, pp. 355-371
The laminin binding alpha(7) beta(1) integrin has been described as a
major integrin in skeletal muscle. The RNA coding for the cytoplasmic
domain of alpha(7) integrin undergoes alternative splicing to generate
two major forms, denoted alpha(7A) and alpha(7B) In the current paper
, we have examined the developmental expression patterns of the alpha(
7A) and alpha(7B) splice variants in the mouse, The alpha(7) integrin
expression is compared to that of the nonintegrin laminin receptor dys
troglycan and to that of laminin-alpha 1 and laminin-alpha 2 chains, a
lpha(7A) integrin was found by in situ hybridization to be specific to
skeletal muscle, Antibodies specific for alpha(7B) integrin and in si
tu hybridization revealed the presence of alpha(7) mRNA and alpha(7B)
protein in the E10 myotome and later in primary and secondary myotubes
, In the heart, alpha(7B) integrin was not detectable in the endocardi
um or myocardium during embryonic and fetal heart development, Norther
n blot analysis and immunohistochemistry revealed a postnatal inductio
n of alpha(7B) in the myocardium, In addition to striated muscle, alph
a(7B) integrin was localized to previously unreported nonmuscle locati
ons such as a subset of vascular endothelia and restricted sites in th
e nervous system. Comparison of the alpha(7) integrin expression patte
rn with that of different laminin isoforms and dystroglycan revealed a
coordinated temporal expression of dystroglycan, alpha(7) integrin, a
nd laminin-alpha 2, but not laminin-alpha 1, in the forming skeletal m
uscle, We conclude that the alpha(7A) and alpha(7B) integrin variants
are expressed in a developmentally regulated, tissue-specific pattern
suggesting different functions for the two splice forms. (C) 1996 Wile
y-Liss, Inc.