Multiple short-chain dehydrogenases/reductases are regulated in pathological cardiac hypertrophy

Abstract

Cardiac hypertrophy (CH) is an important and independent predictor of morbidity and mortality. Through expression profiling, we recently identified a subset of genes (Dhrs7c, Decr, Dhrs11, Dhrs4, Hsd11b1, Hsd17b10, Hsd17b8, Blvrb, Pecr), all of which are members of the short-chain dehydrogenase/reductase (SDR) superfamily and are highly expressed in the heart, that were significantly dysregulated in a rat model of CH caused by severe aortic valve regurgitation (AR). Here, we studied their expression in various models of CH, as well as factors influencing their regulation. Among the nine SDR genes studied, all but Hsd11b1 were down-regulated in CH models (AR rats or mice infused with either isoproterenol or angiotensin II). This regulation showed a clear sex dimorphism, being more evident in males than in females irrespective of CH levels. In neonatal rat cardiomyocytes, we observed that treatment with the α₁-adrenergic receptor agonist phenylephrine mostly reproduced the observations made in CH animals models. Retinoic acid, on the other hand, stimulated the expression of most of the SDR genes studied, suggesting that their expression may be related to cardiomyocyte differentiation. Indeed, levels of expression were found to be higher in the hearts of adult animals than in neonatal cardiomyocytes. In conclusion, we identified a group of genes modulated in animal models of CH and mostly in males. This could be related to the activation of the fetal gene expression program in pathological CH situations, in which these highly expressed genes are down-regulated in the adult heart.

Keywords: Dhrs7c; aortic regurgitation; heart hypertrophy; short‐chain dehydrogenase/reductase.

Figure 1

Many SDR genes highly expressed in the left ventricle (LV) of rats are down‐regulated after chronic aortic valve regurgitation (AR). (A) Heat maps of expression of 35 SDR genes in the LV of sham‐operated or AR male rats for 9 months. Genes were separated into three heat maps depending on their level of expression in sham rats. (B) Comparison of gene expression measured by micro‐array (array) technology vs quantitative RT‐PCR ( qPCR) for nine highly expressed SDR genes. The solid bar set at 1 represents expression of the gene in sham animals. Results are expressed as the mean ± SEM (n = 5). (C) Protein contents of Dhrs7c, Decr1 and 11β‐HSD1 in the myocardium of sham‐operated and AR rats. Glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) protein was used as control. P values were determined using Student's t test.

Figure 2

Sexual dimorphism in the regulation of SDR genes in AR rats. (A) Relative gene expression of the SDR genes in sham females compared to males. The line set at 1 represents expression of the gene in male animals. (B) Cardiac hypertrophy in male and female rats after 6 months of volume overload from AR. HW/BW: heart weight/body weight. (C) After 6 months of AR, no SDR genes are regulated in the LV of AR female rats, whereas a similar regulation of SDR genes as observed in 9‐month AR rats is observed in 6‐month AR males. Results are expressed as the mean ± SEM (n = 8–10 per group). Statistical significance between groups was determined using Student's t test.

Figure 3

The angiotensin I converting enzyme inhibitor (ACEi) captopril reverses the hypertrophic response (A) to experimental volume overload in male AR rats and helps normalize SDR gene expression (B). Rats were treated with captopril for 6 months starting 2 weeks post‐AR induction. The line (B) set at 1 represents expression of the gene in untreated sham animals. Results are expressed as the mean ± SEM (n = 6 per group). (A) *P < 0.05, **P < 0.01 and ***P < 0.001 between groups; ns: non‐significant as determined using ANOVA followed by Tukey's post hoc test. (B) *P < 0.05 vs AR as determined using Student's t test.

Figure 4

A 14‐day continuous infusion of either isoproterenol (Iso) or angiotensin II (AngII) in male mice induces mild cardiac hypertrophy (A) and general down‐regulation of SDR genes (B). Results are expressed as the mean ± SEM (n = 8–10 per group). Statistical significance between groups was determined using Student's t test.

Figure 5

(A) Treatment of neonatal rat cardiac myocytes with Iso, Phe or all‐trans‐retinoic acid (RA) for 24 h regulates SDR gene expression. (B) Regulation of hypertrophy markers in cardiac myocytes by the aforementioned treatments. Results are expressed as the mean and SEM (n = 6 per group). *P < 0.05, **P < 0.01 and ***P < 0.001 vs untreated cardiac myocytes (A; bar set to 1). Statistical significance between groups was determined using Student's t test (A and B).

Figure 6

Short‐chain dehydrogenase/reductase gene expression and protein content are up‐regulated upon cardiac myocytes differentiation. (A) Dhrs7c, Decr1 or 11β‐HSD1 protein content is more abundant in adult rat or mouse LV tissue than in neonatal rat cardiac myocytes (NRCMs). (B) Dhrs7c and Decr1 mRNA levels are up‐regulated with time in culture in NRCMs. (C) Treatment of H9C2 cardiac myoblasts with RA for 24 h up‐regulates SDR gene expression. (D,E) Treatment with differentiation culture medium (1% serum (FBS) + RA 10 nm) results in H9C2 morphological changes (magnification: X200) (D) and strong induction of troponin t (Tnnt) gene expression (E). (F) Most SDR genes are up‐regulated upon H9C2 cardiac myoblast differentiation (7 days). ⁺ P < 0.05 vs H9C2 cells after 24 h of culture in normal medium (10% FBS); *P < 0.05 vs cells after 7 days of culture in 1% FBS. Results are expressed as the mean ± SEM (n = 6 per group). Statistical significance between groups was determined using Student's t test (C) or ANOVA and Tukey's post hoc test (E,F).