The Melanocortin MC5R as a New Target for Treatment of High Glucose-Induced Hypertrophy of the Cardiac H9c2 Cells

Clara Di Filippo,Nicola Alessio,Michele D’Amico,Rosa Maisto,Maria Consiglia Trotta,Anca Hermenean

doi:10.3389/fphys.2018.01475

Clara Di Filippo, Nicola Alessio + Show 4 more

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https://doi.org/10.3389/fphys.2018.01475

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Abstract

The study explored the anti-hypertrophic effect of the melanocortin MC5R stimulation in H9c2 cardiac myocytes exposed to high glucose. This has been done by using α-MSH and selective MC5R agonists and assessing the expression of GLUT4 and GLUT1 transporters, miR-133 and urotensin receptor levels as a marker of cardiac hypertrophy. The study shows for the first time an up-regulation of MC5R expression levels in H9c2 cardiomyocytes exposed to high glucose medium (33 mM D-glucose) for 48 h, compared to cells grown in normal glucose medium (5.5 mM D-glucose). Moreover, H9c2 cells exposed to high glucose showed a significant reduction in cell viability (-40%), a significant increase in total protein per cell number (+109%), and an increase of the urotensin receptor expression levels as an evidence of cells hypertrophy. The pharmacological stimulation of MC5R with α-MSH (90 pM)of the high glucose exposed H9c2 cells increased the cell survival (+50,8%) and reduced the total protein per cell number (-28,2%) with respect to high glucose alone, confirming a reduction of the hypertrophic state as per cell area measurement. Similarly, PG-901 (selective agonist, 10-10 M) significantly increased cell viability (+61,0 %) and reduced total protein per cell number (-40,2%), compared to cells exposed to high glucose alone. Interestingly, the MC5R agonist reduced the GLUT1/GLUT4 glucose transporters ratio on the cell membranes exhibited by the hypertrophic H9c2 cells and increased the intracellular PI3K activity, mediated by a decrease of the levels of the miRNA miR-133a. The beneficial effects of MC5R agonism on the cardiac hypertrophy caused by high glucose was also observed also by echocardiographic evaluations of rats made diabetics with streptozotocin (65 mg/kg i.p.). Therefore, the melanocortin MC5R could be a new target for the treatment of high glucose-induced hypertrophy of the cardiac H9c2 cells.

Highlights

Cardiac hypertrophy is caused by an increased glucose uptake into the cardiac myocytes that determines a high glucose-mediated oxidative stress into the cardiomyocytes (Kagaya et al, 1990; Zhang et al, 1995; Leong et al, 2002; Nascimben et al, 2004; Wang et al, 2009; Han et al, 2015; Wei et al, 2018)
H9c2 cell area quantization showed an evident increase in cell area in cardiomyocytes exposed to high glucose (HG) compared to cells exposed to normal glucose (NG; +58,2%, P < 0,01 vs. NG), indicating a hypertrophic condition (Figure 2)
The high Urotensin II receptor levels in H9c2 cells exposed to high glucose were decreased by α-melanocyte stimulating hormone (α-MSH) (90 pM; −37,9%, P < 0,01 vs. HG) and PG-901 (10−10 M; −40,0%, P < 0,01 vs. HG), while they were not modified by PG-20N treatment (Figure 3A)

Summary

Introduction

Cardiac hypertrophy is caused by an increased glucose uptake into the cardiac myocytes that determines a high glucose-mediated oxidative stress into the cardiomyocytes (Kagaya et al, 1990; Zhang et al, 1995; Leong et al, 2002; Nascimben et al, 2004; Wang et al, 2009; Han et al, 2015; Wei et al, 2018). This increased glucose uptake is mostly due to an imbalance of the translocation. A recent human study showed that single-nucleotide polymorphism in the MC5R was associated with type 2 diabetes in obese subjects (Valli-Jaakola et al, 2008)

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