GH prevents apoptosis in cardiomyocytes cultured in vitro through a calcineurin-dependent mechanism

Abstract

The use of GH to treat heart failure has received considerable attention in recent years. Although the mechanisms of its beneficial effects are unknown, it has been implicated in the regulation of apoptosis in several cell types, and cardiomyocyte apoptosis is known to occur in heart failure. We therefore decided to investigate whether GH protects cardiomyocytes from apoptosis. Preliminary experiments confirmed the expression of the GH receptor (GHR) gene in primary cultures of neonatal rat cardiomyocytes (PC), the specific binding of GH by HL-1 cardiomyocytes, and the GH-induced activation of GHR and its classical downstream effectors in the latter. That GH prevented the apoptosis of PC cells deprived of serum for 48 h was shown by DNA electrophoresis and by Hoechst staining assays in which GH reduced the percentage of cells undergoing apoptosis. Similarly, the TUNEL-evaluated pro-apoptotic effect of cytosine arabinoside (AraC) on HL-1 cells was almost totally prevented by pre-treatment with GH. Fluorescence-activated cell sorter (FACS) analysis showed apoptosis in 9.7% of HL-1 cells growing in normal medium, 21.1% of those treated with AraC and 13.9% of those treated with AraC+GH, and that GH increased the percentage of AraC-treated cells in the S/G(2)/M phase from 36.9% to 52.8%. GH did not modify IGF-I mRNA levels or IGF-I secretion in HL-1 cells treated with AraC, and the protection afforded by GH against AraC-induced apoptosis in HL-1 cells was not affected by the presence of anti-IGF-I antibodies, but was largely abolished by the calcineurin-inhibiting combination cyclosporin+FK506. GH also reduced AraC-induced phosphorylation of mitogen-activated protein kinase p38 (MAPK p38) in HL-1 cells. In summary, GH protects PC and HL-1 cells from apoptosis. This effect is not mediated by IGF-I and may involve MAPK p38 as well as calcineurin.

Flavonoid rich extract of Murraya Koenigii alleviates in-vitro LDL oxidation and oxidized LDL induced apoptosis in raw 264.7 Murine macrophage cells

“…It is of special interest because it can be triggered physiologically (for the removal of damaged or unwanted cells) and pathologically (foam cells in atherosclerosis) which is regulated by the actions of specific gene products resulting in the removal of damaged or unwanted cells (Squier and Cohen 2001). In our study, nuclear morphology was assessed using a fluorescent dye, DAPI (4′,6-Diamidine-2′-phenylindole dihydrochloride) to assess possible apoptotic changes (Gonzalez-Juanatey et al 2004). Ox-LDL treatment provided visual evidence of nuclear condensation as compared to control cells.…”

Acute Alcohol Modulates Cardiac Function as PI3K/Akt Regulates Oxidative Stress

“…This evidence in combination with our findings suggests that IGF-1 can protect against alcohol- induced cardiomyopathy, even in the presence of higher doses of alcohol. Conversely, 1 group was able to show a protective measure of growth hormone in reducing apoptosis in neonatal rat cardiomyocytes; however, they were unable to identify IGF-1 as mediating this effect (Gonzalez-Juanatey et al, 2004). This may be due to the fact that the experiments were performed with neonatal cardiomyocytes which differ in signaling from adult cardiomyocytes.…”

A novel system-level approach using RNA-sequencing data identifies miR-30-5p and miR-142a-5p as key regulators of apoptosis in myocardial infarction

“…It has been suggested that apoptosis is critically linked to the development of heart failure. Growth hormone receptor (GHR) is thought to regulate apoptosis in many cell types including cardiomyocytes through AKT signaling 36 , 37 . In the present study, we found that GHR was significantly downregulated in the heart in MI (Supplementary Fig.…”