Fig. 2.
SPARC deletion delayed age-dependent increase in LV expression of a disintegrin and metalloproteinase with thrombospondin-like motifs 1 (ADAMTS1). A: gene array data of extracellular matrix (ECM). Table shows ECM, which changed with age in the LV of WT, including the ratio (old WT/young WT) and P value (old WT vs. young WT) of each gene expression. B: collagen I mRNA levels decreased with age in both WT and Null mice, whereas collagen III and IV showed age-related decrease in WT but not Null mice. The mRNA levels of collagen V were lower in middle-aged and old WT compared with young WT, whereas only the old group showed lower collagen V mRNA expression vs. the young group in SPARC-null mice. C: among ECM listed in A, SPARC deletion abolished cardiac expression of SPARC mRNA and affected the expression of ADAMTS1, fibronectin 1, Tgfbi, and versican. Age-dependent increases in cardiac expression of ADAMTS1 and transforming growth factor β-induced protein (Tgfbi) were delayed in Null mice compared with WT. Middle-aged Null mice had lower expression of ADAMTS1 than age-matched WT mice. Age-dependent decrease in fibronectin 1 and versican was blunted in SPARC-null mice. Each gene expression was normalized to Hprt1 and shown as 2−ΔCT units. Data are expressed as means ± SE (n = 5–6/group). MMP, matrix metalloproteinase; Ctgf, connective tissue growth factor; Ecm1, extracellular matrix 1; Tgfbi, transforming growth factor β-induced protein; Thbs3, thrombospondin-3. #P < 0.05 among ages in each genotype; *P < 0.05 vs. age-matched WT.