. Wnt-induced secreted protein-1 is a prohypertrophic and profibrotic growth factor. Am J Physiol Heart Circ Physiol 293: H1839-H1846, 2007. First published July 6, 2007; doi:10.1152/ajpheart.00428.2007.-Wnt1-induced secreted protein-1 (WISP-1) is a member of the cysteine-rich 61, connective tissue growth factor, and nephroblastoma overexpressed (CCN) family of growth factors and is expressed in the heart at low basal levels. The purpose of this study was to investigate whether WISP-1 is upregulated in postinfarct myocardium and whether WISP-1 exerts prohypertrophic and mitogenic effects stimulating myocyte hypertrophy, cardiac fibroblast (CF) proliferation, and collagen expression. Male C57Bl/6 (25 g) mice underwent permanent occlusion of the left anterior descending coronary artery. mRNA and protein levels were analyzed by Northern and Western blot analyses. Cardiomyocyte hypertrophy was quantified by protein and DNA synthesis. CF proliferation was quantified by CyQuant assay, and soluble collagen release by Sircol assay. A time-dependent increase in WISP-1 expression was detected in vivo in the noninfarct zone of the left ventricle, which peaked at 24 h (3.1-fold, P Ͻ 0.01). Similarly, biglycan expression was increased by 3.71-fold (P Ͻ 0.01). IL-1␤ and TNF-␣ expression preceded WISP-1 expression in vivo and stimulated WISP-1 expression in neonatal rat ventricular myocytes in vitro. WISP-1-induced cardiomyocyte hypertrophy was evidenced by increased protein (2.78-fold), but not DNA synthesis, and enhanced Akt phosphorylation and activity. Treatment of primary CF with WISP-1 significantly stimulated proliferation at 48 h (6,966 Ϯ 264 vs. 5,476 Ϯ 307 cells/well, P Ͻ 0.01) and enhanced collagen release by 72 h (18.4 Ϯ 3.1 vs. 8.4 Ϯ 1.0 ng/cell, P Ͻ 0.01). Our results demonstrate for the first time that WISP-1 and biglycan are upregulated in the noninfarcted myocardium in vivo, suggesting a positive amplification of WISP-1 signaling. WISP-1 stimulates cardiomyocyte hypertrophy, fibroblast proliferation, and ECM expression in vitro. These results suggest that WISP-1 may play a critical role in post-myocardial infarction remodeling.cysteine-rich 61, connective tissue growth factor, and nephroblastoma overexpressed family; myocardial infarction; myocardial remodeling; Akt; cardiomyocyte hypertrophy WNT1-INDUCED secreted protein-1 (WISP-1) is a member of the cysteine-rich 61, connective tissue growth factor (CTGF), and nephroblastoma overexpressed (CCN) family of growth factors shown to play a role in cellular growth, transformation, and survival (24,26,52,57). Because of the limited regenerative capacity of the heart, any structural adaptations of the myocardium occurring in response to chronic changes in hemodynamic loading conditions typically require alterations in the size of myocytes and composition of the interstitial components (46). When the stimulus is chronic pressure overload, as in hypertension or aortic stenosis, cardiac myocytes increase in diameter and there is increased deposition of interstitial col...

Stimulated production of reactive oxygen species (ROS) by plasma membrane-associated nicotinamide adenine dinucleotide phosphate oxidases (Nox) in non-phagocytic cells regulates a number of biological processes including growth, vessel tone, and oxygen sensing. The purpose of this study was to investigate H 2 O 2 -stimulated ROS production in primary adult cardiac fibroblasts (CF). Results demonstrate that CF express an H 2 O 2 -inducible oxidant generating system that is inhibitable by diphenylene iodonium (DPI) and sensitive to antioxidants. In addition to H 2 O 2 , generation of ROS was stimulated potently by 1-oleoyl-2-acetyl-sn-glycerol (OAG) and arachidonic acid (AA) in a protein kinase C-independent manner. Pretreatment with arachidonyl trifluoromethyl ketone was nearly as effective as DPI at reducing H 2 O 2 -and OAG-stimulated oxidant generation indicating a central role for phospholipase A 2 (PLA 2 ) in this signaling pathway. Co-stimulation with H 2 O 2 and OAG did not increase ROS generation as compared to OAG alone suggesting both agonists signal through a shared, rate-limited enzymatic pathway involving PLA 2 . Co-stimulation with H 2 O 2 and AA had additive effects indicating these two agonists stimulate oxidant production through a parallel activation pathway. Reverse transcriptase-coupled polymerase chain reaction and Western blotting demonstrate primary cardiac fibroblasts express transcripts and protein for Nox4, p22, p47, and p67 phox. Transfections with Nox4 small inhibitory ribonucleic acid oligonucleotides or p22 phox antisense oligonucleotides significantly downregulated stimulated Nox activity. Inhibitors of nitric oxide synthases were without effect. We conclude adult CF express Nox4/p22 phox-containing oxidant generating complex activated by H 2 O 2 , OAG, and AA through a pathway that requires activation of PLA 2 .

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Interleukin (IL)-18 is a cardiotropic proinflammatory cytokine chronically elevated in the serum of patients with cardiac hypertrophy (LVH). The purpose of this study was to examine the role of IL-18 in pressure-overload hypertrophy using wild type (WT) and IL-18 −/− (null) mice. Adult male C57Bl/ 6 mice underwent transaortic constriction (TAC) for 7 days or sham surgery. Heart weight/body weight ratios showed blunted hypertrophy in IL-18 null TAC mice compared to WT TAC animals. Microarray analyses indicated differential expression of hypertrophy-related genes in WT versus IL-18 nulls. Northern, Western, and EMSA analyses showed Akt and GATA4 were increased in WT but unchanged in IL-18 null mice. Our results demonstrate blunted hypertrophy with reduced expression of contractile-, hypertrophy-, and remodeling-associated genes following pressure overload in IL-18 null mice, and suggest that IL-18 plays a critical role in the hypertrophic response.