Smooth muscle cell–extrinsic vascular spasm arises from cardiomyocyte degeneration in sarcoglycan-deficient cardiomyopathy
J. Clin. Invest. Matthew T. Wheeler, et al. 113:668 doi:10.1172/JCI20410 [
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Figure 1Construction and expression of cardiomyocyte-specific sarcoglycan transgenes. (A) Full-length murine γ-sarcoglycan (γ-sg) or δ-sarcoglycan (δ-sg) cDNA was ligated into a vector containing the 5.6-kb murine α-MHC promoter (
15) to create MHG or MHD, respectively. Transgenic mice with the MHG transgene were crossed with γ-sarcoglycan–null (
gsg–/–) mice to generate
gsg–/–/MHG mice. Transgenic mice with the MHD transgene were crossed with δ-sarcoglycan–null (
dsg–/–) mice generating
dsg–/–/MHD mice. pA, polyadenylation signals. (B) Immunoblot of whole heart extracts from normal,
gsg–/–,
dsg–/–,
gsg–/–/MHG, and
dsg–/–/MHD animals at 12 weeks of age using γ-sarcoglycan Ab showed γ-sarcoglycan expression was absent in the hearts of
gsg–/– and
dsg–/– animals, but was restored in transgenic animals. Quantitative Western blot analysis determined the level of γ-sarcoglycan expression in
gsg–/–/MHG animals to be sevenfold above normal. (C) δ-Sarcoglycan expression was restored to normal levels by expression of the MHD transgene in
dsg–/–/MHD hearts. Expression of δ-sarcoglycan from the MHD transgene also resulted in recovery of γ-sarcoglycan to normal levels (last lane). (D) Immunoblots for the remaining sarcoglycan subunits showed that α-sarcoglycan (ASG) expression is recovered in hearts with either γ- or δ-sarcoglycan transgene expression. β-Sarcoglycan protein (BSG) is increased to normal levels, and ζ-sarcoglycan protein (ZSG) levels are not significantly different in transgenic hearts. Loading control is shown for B, C, and D. Coom., Coomassie blue.
