Analysis of differentially expressed genes in hyperthyroid-induced hypertrophied heart by cDNA microarray

Abstract

Experiments were carried out to identify the altered genes in hyperthyroid rat heart and their influence on the functions of cardiac myocytes. Chronic treatment of rats with 3,5,3 triiodo--thyronine (T3) resulted in a prominent increase in the size of the left ventricle with increased wall thickness and reduced chamber volume leading to concentric cardiac hypertrophy. The heart weight to body weight ratio (HW/BW) in hyperthyroid rats was increased by about 58% over that of normal rats. Using cDNA microarray comprising 588 genes, we compared the differences in mRNA expression of hyperthyroid and normal rat heart. Based on a threshold of greater than 10% change, about 37 genes were found to be regulated by T3. Further analyses by Western blotting, Northern blotting and real-time quantitative RT-PCR of some of the genes confirmed the microarray results. The T3-altered genes encode various types of proteins related to metabolism, matrix and cytoskeletal structures, growth factors, transcription factors, Ca 2+ -channels etc. The physiological significance of one of these altered proteins in hyperthyroid heart, insulin-responsive glucose transporter (GLUT) type 4 (GLUT4), was studied in detail. The expression of GLUT4 was drastically reduced in the ventricular tissues of hyperthyroid heart. Insulin-induced glucose uptake in hyperthyroid cardiomyocytes was reduced significantly, indicating the impaired glucose transport in cardiac cells. Interestingly, a few genes such as GLUT4, cytochrome P450 isoforms, superoxide dismutase (SOD), collagens, matrix metalloproteinases (MMP), tissue inhibitors of matrix metalloproteinases etc. which had not been reported earlier were found to be altered in hyperthyroid heart. Our results show some new aspects of hyperthyroid heart which will be important in assessing the pathophysiology of hypertrophied cardiomyocytes.

Acyl-CoA synthetase 1 deficiency alters cardiolipin species and impairs mitochondrial function

“…In the heartspecifi c knockout of Acsl1 , remarkable alterations were observed in the expression of genes related to activated mTORC1, but we did not identify tafazzin expression as being signifi cantly reduced ( 31 ). The regulation of tafazzin has not been fully studied; however, decreased mRNA expression has been reported with thyroxine treatment ( 32 ), which results in an increase in total CL content without favoring the formation of tetralinoleoyl-CL ( 33 ). Heart failure also diminishes tafazzin expression ( 34 ) and tetralinoleoyl-CL content ( 35 ), demonstrating a physiological relationship between tafazzin expression and CL species.…”

Cytosolic Dynamics of Annexin A6 Trigger Feedback Regulation of Hypertrophy via Atrial Natriuretic Peptide in Cardiomyocytes

“…Adding selection antibiotics to transfected cells, according to predetermined kill curves, generated Table 2. Relative quantification of transcript profiles was performed as described earlier (28). Briefly, cDNA synthesized from 500 ng of total RNA extracted from cells, were subjected to quantitative PCR using SYBR Green chemistry.…”

“…25-100 g of elutes were used for subsequent Western blot analysis. SDS-PAGE, immunoblotting, detection, and densitometric quantification were performed as described elsewhere (28).…”

Hyperthyroidism causes cardiac dysfunction by mitochondrial impairment and energy depletion

“…Rats with a body weight (BW) of 180-220 g were randomly assigned to the following treatment groups: control (nZ12), triiodothyronine (T 3 ) (nZ12), T 3 Cbezafibrate (Bzf) (nZ12), and Bzf (nZ8). Hyperthyroidism was induced by intraperitoneally injecting the rats daily with 8 mg/100 g BW T 3 (Sigma Chemical Co.) for 15 days (T 3 ) as described earlier (De et al 2004). To study the progression of cardiac dysfunction induced by hyperthyroidism, rats were also treated with T 3 for 2 days D2 (nZ6), 5 days D5 (nZ6), and 8 days D8 (nZ6).…”