Interleukin-1β Inhibits Phospholamban Gene Expression in Cultured Cardiomyocytes

Abstract

Phospholamban is a key regulatory protein that defines diastolic function. Proinflammatory cytokines interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) can depress contractility and intracellular Ca2+ currents and transients. An alteration in phospholamban expression is a possible pathway by which these cytokines modulate cardiac function. To test this hypothesis, primary cultures of neonatal rat cardiomyocytes were incubated with IL-1 beta, TNF-alpha, or both, and the level of phospholamban transcripts was examined by Northern blot analyses. Phospholamban transcript levels were decreased approximately equal to 50% (P < .0001) in cells exposed to 2 ng/mL IL-1 beta (20 hours), whereas TNF-alpha had no effect. Western blot analyses showed that IL-1 beta also reduced phospholamban protein levels (60% of control, P < .0001). The effects on transcript levels were gene specific; IL-1 beta induced transcripts for inducible NO synthase (iNOS), did not alter GAPDH transcripts, and reduced sarcoplasmic reticulum Ca(2+)-ATPase (65% of control, P < .001) transcripts. Cardiomyocytes treated with IL-1 beta showed no alterations in basal contractile parameters (maximum velocity of contraction and relaxation and maximal amplitude of contraction) but were unresponsive to beta-adrenergic stimulation. Studies performed in the presence of second-messenger inhibitors showed that the effect of IL-1 beta on phospholamban transcript levels was blocked by dexamethasone, was insensitive to inhibitors of iNOS, cyclooxygenase, or tyrosine kinases, but was enhanced by the addition of the protein kinase inhibitor staurosporine. These data demonstrate that IL-1 beta alters the expression of phospholamban, a key regulator of cardiac contractility, at both the transcript and protein levels. The results suggest novel mechanisms by which IL-1 beta may modify cardiac function.

Activation of invariant natural killer T cells by α-galactosylceramide ameliorates myocardial ischemia/reperfusion injury in mice

“…Moreover, IL-10 induces protection against myocardial injury by preventing apoptosis through the reduced phosphorylation of p38MAPK and the enhanced phosphorylation of STAT3 [42]. TNF-α and IL-1β promotes apoptosis in cardiac myocytes [43,44], which is also inhibited by IL-10. In the present study, we demonstrated that αGC administration ameliorated myocardial I/R injury (Figure 3) with upregulating serum and myocardial IL-10 ( Figure 6).…”

Interleukin-1β Reduces L-type Ca2+ Current through Protein Kinase Cϵ Activation in Mouse Heart

“…ulate the gene expression of multiple ion channels and proteins (15,17,35,36); we therefore examined whether IL-1␤ could alter gene expression of Ca V 1.2. The qPCR results shown in Fig.…”

Adenosine Inhibits Lipopolysaccharide-Induced Cardiac Expression of Tumor Necrosis Factor-α

“…15,21 Neonatal cardiomyocytes were prepared as described above, plated onto glass coverslips, and cultured in the presence of LPS (E coli 0127, 100 ng/mL), LPS and adenosine (10 mol/L), or diluent for 4 days. Treatments were performed after isolation and repeated on days 2 and 4.…”