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Molecular Medicine |
From the Division of Cardiology (K.K., M.R.B.), University of Colorado Health Sciences Center, Denver, Colo; Department of Cardiovascular Medicine (K.Y., Y.E., T.A.), Graduate School of Medicine, University of Tokyo, Japan; Department of Pharmaceutical Sciences (R.C.J.R.), University of Brasília, Brazil; Metabolic Research Unit, Diabetes Center, and Department of Medicine (J.D.B.), University of California, San Francisco, Calif; Department of Medicine (Cardiology) (S.A.C.), San Francisco General Hospital, San Francisco, Calif; Cardiology Section (C.S.L.), Denver Health Medical Center, Denver, Colo; and Veterans Affairs Medical Center and Cardiovascular Research Institute and Department of Medicine (P.C.S.), University of California, San Francisco, Calif.
Correspondence to Paul C. Simpson, MD, VA Medical Center (111-C-8), 4150 Clement St, San Francisco, CA 94121. E-mail pcs{at}itsa.ucsf.edu
| Abstract |
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- and ß-myosin heavy chain (MyHC) and sarcoplasmic reticulum Ca2+-ATPase (SERCA), and TH treatment can reverse molecular and functional abnormalities in pathological hypertrophy, such as pressure overload. These findings suggest relative hypothyroidism in pathological hypertrophy, but serum levels of TH are usually normal. We studied the regulation of TH receptors (TRs) ß1,
1, and
2 in pathological and physiological rat cardiac hypertrophy models with hypothyroid- and hyperthyroid-like changes in the TH target genes,
- and ß-MyHC and SERCA. All 3 TR subtypes in myocytes were downregulated in 2 hypertrophy models with a hypothyroid-like mRNA phenotype, phenylephrine in culture and pressure overload in vivo. Myocyte TRß1 was upregulated in models with a hyperthyroid-like phenotype, TH (triiodothyronine, T3), in culture and exercise in vivo. In myocyte culture, TR overexpression, or excess T3, reversed the effects of phenylephrine on TH-responsive mRNAs and promoters. In addition, TR cotransfection and treatment with the TRß1-selective agonist GC-1 suggested different functional coupling of the TR isoforms, TRß1 to transcription of ß-MyHC, SERCA, and TRß1, and TR
1 to
-MyHC transcription and increased myocyte size. We conclude that TR isoforms have distinct regulation and function in rat cardiac myocytes. Changes in myocyte TR levels can explain in part the characteristic molecular phenotypes in physiological and pathological cardiac hypertrophy.
Key Words: thyroid hormone receptor physiological and pathological hypertrophy
1-adrenergic receptor cardiac myocyte rat
| Introduction |
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TH-responsive genes in cardiac muscle include
-myosin heavy chain (MyHC) and sarcoplasmic reticulum Ca2+-ATPase (SERCA), which are induced by TH, and ß-MyHC, which is repressed.7,8 An intriguing observation is that pathological hypertrophy is characterized by hypothyroid-like changes in these target genes, with decreases in
-MyHC and SERCA and increases in ß-MyHC, a molecular phenotype also called the fetal program.9 The fact that TH treatment can reverse these genetic changes in some models of pathological hypertrophy is additional evidence for a hypothyroid state, but TH blood levels are usually normal.3 Conversely, physiological hypertrophy caused by exercise is characterized by hyperthyroid-like changes in TH target genes, yet again blood TH levels are normal.10 Only in cardiac hypertrophy during normal postnatal development are changes in TH-responsive genes attributable clearly to altered TH levels.11,12
Transcription of TH target genes is mediated by nuclear TH receptors (TRs), with 2 genes,
and ß, encoding at least 4 major TRs, ß1, ß2,
1, and
2,13,14 as well as minor variants, including TRß3.15 TRs ß1,
1, and
2 are expressed widely. TRß2 is present mainly in pituitary cells but might be a small fraction of T3-binding TRs in heart, as found in one study.16 TR
2 binds thyroid response elements (TREs) on DNA but does not bind 3,3',5-triiodo-L-thyronine (T3), the active form of TH, and can function as a dominant negative.13,17 TRs ß1 and
1 bind T3 with similar affinity but exhibit subtle differences in binding to TREs and cofactors and in forming homodimers and heterodimers with retinoid X receptors.13,1820 Consistent with these biochemical differences, mouse TR knockouts reveal nonredundant TR functions in many tissues.1921 In the heart, however, TR knockouts suggest that the transcription effects of TH are mediated largely by TR
1.17,22 TR functions have not been evaluated systematically in isolated myocytes.
In this study, we tested the hypothesis that hypothyroid- and hyperthyroid-like transcription changes in pathological and physiological hypertrophy are caused by altered TR levels in heart and myocytes. Recent studies in the aging rat and in human end-stage heart failure reveal changes in myocardial TR levels that correlate with changes in TH target gene transcription.23,24 However, possible changes in TR levels in hypertrophy have not been examined, and TR functions on target promoters in myocytes have not been compared. We measured TRs in rat hypertrophy models in culture and in vivo and tested TR functions in culture using transfection and treatment with T3 or a TRß1-selective agonist.
| Materials and Methods |
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-MyHC (2900 bp), ß-MyHC (3300 bp), or SERCA (3500 bp).29
Hypertrophy In Vivo
Hypertrophy was induced in adult male Wistar rats by voluntary wheel running for 10 weeks (age 7 to 17 weeks) or by ascending aortic constriction (pressure gradient
75 mm Hg) for 4 weeks (age 10 to 14 weeks).30 Serum levels of total 3,3',5,5'-tetraiodo-L-thyronine (T4) and total T3 were measured by ELISA (ICN Pharmaceuticals).
RNase Protection Assay (RPA) for TH-Responsive mRNAs
Total RNA was extracted from cells or ventricles with TRIZol (GIBCO) and used in RPA with a probe for
- and ß-MyHC and a probe for SERCA2a plus GAPDH as an internal control (see expanded Materials and Methods, available in the online data supplement at http://www.circresaha.org).25
TH Receptors
For TR mRNAs, RPA was used with probes specific for the rat TR isoforms, and GAPDH was used as an internal control (see the expanded Materials and Methods section).24 For TR proteins, cultured myocyte nuclear and cytoplasmic fractions27 were used in Western blot with monoclonal antibodies from Santa Cruz (J51/SC-737 specific for human TRß1; J52/SC-738 reactive with rat and human TRß1).31 Human and rat TRß1 proteins for standards were synthesized using rabbit reticulocyte lysate (TNT T7 Quick Coupled Transcription/Translation System, Promega).28,32
Statistics
Data shown are mean±SE and were compared by one-way ANOVA and the Newman-Keuls test.
An expanded Materials and Methods section can be found in the online data supplement available at http://www.circresaha.org.
| Results |
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-MyHC and SERCA mRNA levels, and repressed ß-MyHC to 5% of control. The
1-adrenergic receptor (AR) hypertrophic agonist PE (20 µmol/L) had opposite effects on these mRNAs, increasing ß-MyHC and decreasing SERCA and
-MyHC. Prazosin (2 µmol/L) inhibited all PE effects, confirming
1-AR dependence (n=3 cultures, data not shown).
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Under our basal, serum-free culture conditions, medium T3 levels averaged about 0.1 nmol/L over the 3-day time course of these experiments, presumably reflecting myocyte release of stored T3.3335 Interestingly, when 1000-fold excess T3 (100 nmol/L) was added to PE-treated myocytes, all PE effects on TH-responsive transcripts were reversed, with significant increases in
-MyHC and SERCA and decreases in ß-MyHC (Table 1). The antagonistic relationship between
1-AR and T3 signaling was not explained by a lesser degree of hypertrophy, because hypertrophy was even greater with PE plus T3 (Table 1).
In intact rat hypertrophy models, voluntary running exercise stimulated hypertrophy with an mRNA profile similar to T3 in culture (Table 1). Conversely, pressure overload by ascending aortic constriction caused hypertrophy with changes in TH target mRNAs opposite to exercise and similar to PE in culture (Table 1). Thus, in agreement with previous studies (discussed in the Introduction), 2 hypertrophy models had signature mRNA changes of heightened thyroid signaling, T3 in culture and exercise in vivo. In contrast, 2 other models had a directionally opposite pattern of hypothyroid-like signaling, PE in culture and pressure overload in vivo. T3 and T4 blood levels in the intact rat models were similar among all 4 groups, with total T4
40 nmol/L (3 to 3.2 µg/dL) and total T3
1 nmol/L (52 to 55 ng/dL) (n=6 to 13, P=NS), as found by others.3,10 Thus, mRNA changes were not explained by changes in circulating TH concentration.
TR Levels in Hypertrophy Models in Culture
To test if some change in thyroid signaling besides TH concentration might explain changes in transcription of TH-responsive genes in hypertrophy, we first measured TR levels in cultured myocytes. In cultured myocytes under basal, serum-free conditions, RPAs detected the mRNAs for TRs
2,
1, and ß1, with a molar ratio of
7:3:1. TRß2 mRNA was not found, using a probe validated in rat pituitary GC cells (not shown), and TRß3 was not tested. Treatment with T3 under conditions that stimulated hypertrophy (Table 1) caused an increase in TRß1 mRNA, with a maximum
2-fold and an EC50
3 nmol/L, but had no effect on TR
2 or
1 (Figure 1A). T3 induction of TRß1 in myocytes was significant as early as 12 hours and maximum at 48 hours (data not shown). Thus TRß1 itself was a TH-responsive gene in myocytes and was increased in T3-stimulated hypertrophy.
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PE-induced hypertrophy in cultured myocytes had an effect different from T3 and reduced the levels of all 3 TR isoform mRNAs to 50% to 75% of control (Figure 1B). The EC50 for TR repression was about 3 µmol/L (Figure 1B), similar to the EC50 for PE-induced hypertrophy, and the PE effect was detected as early as 6 hours (data not shown). PE is an
1-AR agonist with weak ß-AR activity, and specific
1-AR repression of TRs was confirmed in separate experiments with norepinephrine, isoproterenol, prazosin, and timolol (all 2 µmol/L, n=3 to 4 cultures for each, data not shown). Interestingly, and similar to the other TH target mRNAs (Table 1), addition of T3 reversed PE repression of TRß1, but TRs
1 and
2 were not changed (Figure 1B).
To test if TR mRNA levels reflected TR protein, we measured endogenous TRs in cultured myocytes by Western blot. None of the commercial antibodies from Santa Cruz or Affinity BioReagent gave specific signals for TRs
1 and
2 (not shown), but TRß1 protein was detected in nuclear extracts (Figure 1). PE reduced TRß1 protein significantly, whereas T3 increased TRß1 and reversed TRß1 repression caused by PE (Figures 1A and 1B). Thus TRß1 mRNA and protein changes were concordant.
Cultured cardiac nonmyocytes also expressed mRNAs for all 3 of the TRs found in myocytes,
1,
2, and ß1, but levels were not altered by PE 20 µmol/L or T3 100 nmol/L (n=3 cultures, data not shown). No response to PE can be explained by the absence of
1-ARs in nonmyocytes.36 No response to T3 is compatible with a requirement for cell-specific factors such as MEF-2 in myocyte TR signaling.37,38
TR mRNA Levels in Hypertrophy Models In Vivo
Control adult male rat hearts contained mRNAs for TRs
2,
1, and ß1 at equal molar ratios (
1:1:1). Physiological hypertrophy stimulated by voluntary running exercise mimicked T3 in culture, with an increase in TRß1 mRNA and no change in TRs
1 and
2 (Figure 2). Pathological hypertrophy stimulated by ascending aortic constriction was similar to PE in culture, with decreases in all 3 TR isoform mRNAs (Figure 2), detectable as early as 1 week after banding (not shown). Thus, in distinct hypertrophy models in vivo as in culture, TR isoform levels and TH-responsive transcript levels were related directly (Figure 2 and Table 1).
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Cotransfection of TR Isoforms and TH-Responsive Promoters
To test directly whether changes in TR levels could alter TH-responsive transcription, we cotransfected cultured myocytes with expression plasmids for the human TR isoforms and reporter plasmids for the TH-responsive genes (Figure 3). The Western blot in Figure 3A shows that human TRß1 was detected in nuclear extracts from TRß1-transfected myocytes, with overflow of transfected TRß1 into the cytosolic fraction, suggesting saturating levels.31 Similarly, an antibody recognizing both human and rat TRß1 indicated that total TRß1 nuclear levels in transfected cultures were about 2-fold over endogenous (Figure 3A). With
5% of myocytes transfected,39 this result implied about 40-fold overexpression of TRß1.
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We used this system to test the effects of increasing TR isoform levels on
-MyHC, ß-MyHC, and SERCA promoters. In vehicle-treated control myocytes, overexpression of TR
1 activated the
-MyHC promoter, and TRß1 repressed ß-MyHC (Figure 3B). TR
2 had no effect. Induction of
-MyHC indicated that TR
1 was expressed, even though Western blots were unsatisfactory for TR
protein levels.
In PE-treated myocytes transfected with empty vector, the ß-MyHC promoter was activated, and
-MyHC and SERCA promoters were repressed (Figure 3C), similar to the PE effects on endogenous mRNAs (Table 1). Increasing the levels of TR
1 by transfection reversed PE repression of
-MyHC, whereas TRß1 overexpression significantly opposed the effects of PE on both ß-MyHC and SERCA. Interestingly, forced expression of TR
2, the non-T3-binding TR, slightly but significantly enhanced PE repression of
-MyHC and SERCA (Figure 3C).
In T3-treated myocytes transfected with empty vector, the ß-MyHC promoter was repressed and
-MyHC and SERCA were activated (Figure 3D), as expected from T3-induced mRNA changes (Table 1). Overexpression of TRß1 in T3-treated myocytes significantly enhanced induction of the SERCA promoter, but TRs
1 and
2 had no effects over T3 alone (Figure 3D).
Taken together, these cotransfection results showed that increasing the levels of T3-binding TRs altered TH-responsive transcription and antagonized the effects of PE on TH-responsive genes. In addition, the results suggested different functions of TRs in myocytes, regulation of
-MyHC by TR
1, and regulation of ß-MyHC and SERCA by TRß1. The repressive effect of TR
2 only in PE-treated cells (Figure 3C) was consistent with a weak dominant-negative effect of this nonT3-binding TR (see the Introduction) that could be detected only when levels of the T3-binding TRs were reduced by PE (Figure 1B).
Effects of a TRß1-Selective Agonist on Myocyte Transcription and Hypertrophy
To test different functional roles for TR isoforms by a second approach not involving transfection, we treated myocytes with GC-1, which has
10-fold selectivity for TRß1 versus TR
1 but has not been tested with TRs ß2 and ß3, and compared the responses to T3, which binds with similar affinity to both TRs ß1 and
1.18,35 We assayed both TH-responsive promoter activities and endogenous mRNAs (Figures 4A and 4B) and also RLP, an index of total protein content or overall myocyte size (Figure 4C). As shown in Figures 4A through 4C and summarized in Table 2, the EC50s for GC-1 induction of SERCA and repression of ß-MyHC were identical to the EC50s for T3, whereas GC-1 was at least 10-fold less potent than T3 in induction of
-MyHC and RLP. These data were consistent with the cotransfection experiments (Figure 3) and suggested preferential coupling of TRß1 to ß-MyHC and SERCA, whereas TR
1 regulated
-MyHC and total protein content. In addition, GC-1 increased TRß1 mRNA by 203±28% at 100 nmol/L with an EC50 of 2 nmol/L (P<0.05 versus vehicle, n=5), almost identical to the effect of T3 (Figure 1 and Table 2), consistent with the notion that TRß1 activated its own transcription.
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| Discussion |
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We detected 3 TRs in rat myocytes, ß1,
1, and
2, and all were reduced by pressure overload in vivo and
1-AR signaling in culture (Figures 1 and 2), the models with hypothyroid-like transcription changes (Table 1). Reversal of hypothyroid signaling when TRs ß1 and
1 were overexpressed in the PE culture model supported the causal significance of TR downregulation (Figure 3C). Downregulation of dominant-negative TR
2 in both models would have been expected to partly counteract the hypothyroid effects of decreased TRs ß1 and
1, because overexpressed TR
2 had hypothyroid effects when TRs ß1 and
1 were reduced by PE (Figure 3C). Nevertheless, global TR downregulation in both models of pathological hypertrophy was associated with reduced transcription of TH target genes.
Abnormal TR levels are also seen at a terminal stage of pathological hypertrophy, severe human heart failure. In human heart failure, TR
1 is decreased and TR
2 is increased, probably because of altered splicing of the TR
gene, and the increase in TR
2 correlates with reduced
-MyHC transcription.24 In our rat models of PE treatment and pressure overload, the global decrease in all TR mRNAs could be explained by reduced TR gene transcription or increased TR mRNA degradation. Thus the specific mechanism for altered TR levels might differ among species or models, but the human and rat studies both suggest that TR downregulation is a mechanism for hypothyroid-like signaling in pathological hypertrophy. This relationship was additionally strengthened by our converse results in physiological models.
TR upregulation was seen in exercise, a model of physiological hypertrophy with normal or enhanced contractile function.30 Voluntary running exercise caused an increase in TRß1 but no change in TR
(Figure 2). T3 in culture also caused selective induction of TRß1 (Figure 1) and similarly induces a physiological hypertrophy in vivo.5 Our finding that the TRß1 gene is TH-responsive in myocytes but the TR
gene is not agrees with some studies in the intact rat,40,41 but not with others,42 and can be explained by positive TREs in the TRß1 promoter that are absent in TR
.43,44 Furthermore, the TRß1 gene seemed to be activated by TRß1 itself, because T3 and the TRß1-selective agonist GC-1 induced TRß1 with similar potency (Table 2). Thus, exercise-induced increases in TRß1 levels should be partly self-sustaining, and the increase in TRß1 would augment transcription of downstream TH target genes on the basis of our transfection studies (Figure 3).
TRß1 in myocytes differed from TR
1 in induction by T3 and also in function. In this study, we made the first systematic comparison of TR function in isolated myocytes and found by 2 complimentary approaches that TRß1 induced SERCA and TRß1 itself and repressed ß-MyHC, whereas TR
1 increased
-MyHC and protein content (Figures 3 and 4 and Table 2). Notably, the same pattern of TR function was seen with TR cotransfection and with GC-1, which has
10-fold selectivity for TRß1.18 Distinct TR isoform effects on different promoters might be explained by isoform-specific interactions with cofactors or differing affinities for TREs (see the Introduction). Interestingly, target genespecific differences were evident even for a single TR isoform in that TRß1 more potently repressed ß-MyHC than it activated SERCA and activated SERCA more potently than TRß1 itself (Table 2). Also intriguing was the correlation of TR
1 signaling with increased total protein content, an index of overall hypertrophy (Figure 4C and Table 2). Increased protein content requires increased translation as well as transcription, thus raising the question of nongenomic effects of T3 via TR
1.
Previous results from rat and human models are consistent with the distinct transcription functions of TR isoforms we show in this study. In the aging rat, increased ß-MyHC transcription correlates with decreased TRß1 levels and reduced
-MyHC correlates with reduced TR
1.23 A correlation between levels of TR
1 and
-MyHC is also seen in the failing human heart.24 A preferential effect of GC-1 on myocardial SERCA and ß-MyHC is not seen in the rat in vivo, but this might be because of lower bioavailability of GC-1 in cardiac tissue.35 On the other hand, the mouse might be different from rat and human, because knockout studies suggest that most cardiac effects of T3 can be accounted for by TR
1.17,22 Whether both TRs are required for full TH effects in heart is one key consideration in potential therapeutic uses of TH signaling,8 and additional study is needed.
Finally, the question arises of whether other mechanisms alter TH signaling in hypertrophy in addition to changes in TR levels. Pertinent is the effect of T3 in the culture model, where a 1000-fold increase in medium T3 (from 0.1 to 100 nmol/L) reversed PE antagonism of all TH-responsive genes, including the MyHCs, SERCA, and TRß1, despite PE reduction of TR levels (Table 1 and Figure 1). Thus, excess T3 in culture could counteract the hypothyroid effects of reduced TRs. In vivo as well, high doses of T3 reverse hypothyroid transcription in pressure overload models3,5 despite the reduced TR levels we show in this study (Figure 2). The reversal effect of excess T3 can be explained partly by induction of TRß1 and downstream changes in other TH-responsive genes, but the T3 effect also suggests that cellular T3 levels might be limiting in some cases. Thus it is possible that myocyte T3 metabolism3335 is changed in hypertrophy, with increases in cellular T3 with exercise and decreases with pressure overload and PE, and this requires additional study.
In summary, changes in TR levels can explain at least in part the characteristic hypothyroid- and hyperthyroid-like transcription in different types of hypertrophy. TH signaling is impaired in pathological hypertrophy and enhanced in physiological hypertrophy.
| Acknowledgments |
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| Footnotes |
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Received June 19, 2001; accepted July 27, 2001.
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A. Makino, J. Suarez, H. Wang, D. D. Belke, B. T. Scott, and W. H. Dillmann Thyroid Hormone Receptor-{beta} Is Associated with Coronary Angiogenesis during Pathological Cardiac Hypertrophy Endocrinology, April 1, 2009; 150(4): 2008 - 2015. [Abstract] [Full Text] [PDF] |
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N. Gassanov, F. Er, G. Michels, N. Zagidullin, M. C. Brandt, and U. C. Hoppe Divergent regulation of cardiac KCND3 potassium channel expression by the thyroid hormone receptors {alpha}1 and {beta}1 J. Physiol., March 15, 2009; 587(6): 1319 - 1329. [Abstract] [Full Text] [PDF] |
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S. Chen, D. J. Glenn, W. Ni, C. L. Grigsby, K. Olsen, M. Nishimoto, C. S. Law, and D. G. Gardner Expression of the Vitamin D Receptor Is Increased in the Hypertrophic Heart Hypertension, December 1, 2008; 52(6): 1106 - 1112. [Abstract] [Full Text] [PDF] |
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S. K. Ambler, Y. K. Hodges, G. M. Jones, C. S. Long, and L. D. Horwitz Prolonged administration of a dithiol antioxidant protects against ventricular remodeling due to ischemia-reperfusion in mice Am J Physiol Heart Circ Physiol, September 1, 2008; 295(3): H1303 - H1310. [Abstract] [Full Text] [PDF] |
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O. M. Hyyti, A. K. Olson, M. Ge, X.-H. Ning, N. E. Buroker, Y. Chung, T. Jue, and M. A. Portman Cardioselective dominant-negative thyroid hormone receptor ({Delta}337T) modulates myocardial metabolism and contractile efficiency Am J Physiol Endocrinol Metab, August 1, 2008; 295(2): E420 - E427. [Abstract] [Full Text] [PDF] |
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R. Ventura-Clapier, A. Garnier, and V. Veksler Transcriptional control of mitochondrial biogenesis: the central role of PGC-1{alpha} Cardiovasc Res, July 15, 2008; 79(2): 208 - 217. [Abstract] [Full Text] [PDF] |
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J. A. Hill and E. N. Olson Cardiac Plasticity N. Engl. J. Med., March 27, 2008; 358(13): 1370 - 1380. [Full Text] [PDF] |
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C R Liu, L Y Li, F Shi, X Y Zang, Y M Liu, Y Sun, and B H Kan Effects of hyper- and hypothyroid on expression of thyroid hormone receptor mRNA in rat myocardium J. Endocrinol., December 1, 2007; 195(3): 429 - 438. [Abstract] [Full Text] [PDF] |
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D. S. Hydock, C.-Y. Lien, C. M. Schneider, and R. Hayward Effects of voluntary wheel running on cardiac function and myosin heavy chain in chemically gonadectomized rats Am J Physiol Heart Circ Physiol, December 1, 2007; 293(6): H3254 - H3264. [Abstract] [Full Text] [PDF] |
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C. Pantos, A. Dritsas, I. Mourouzis, A. Dimopoulos, G. Karatasakis, G. Athanassopoulos, S. Mavrogeni, A. Manginas, and D. V Cokkinos Thyroid hormone is a critical determinant of myocardial performance in patients with heart failure: potential therapeutic implications Eur. J. Endocrinol., October 1, 2007; 157(4): 515 - 520. [Abstract] [Full Text] [PDF] |
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C. Pantos, I. Mourouzis, K. Markakis, A. Dimopoulos, C. Xinaris, A. D. Kokkinos, M. Panagiotou, and D. V. Cokkinos Thyroid hormone attenuates cardiac remodeling and improves hemodynamics early after acute myocardial infarction in rats Eur. J. Cardiothorac. Surg., August 1, 2007; 32(2): 333 - 339. [Abstract] [Full Text] [PDF] |
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J. A. Kuzman, T. D. O'Connell, and A. M. Gerdes Rapamycin Prevents Thyroid Hormone-Induced Cardiac Hypertrophy Endocrinology, July 1, 2007; 148(7): 3477 - 3484. [Abstract] [Full Text] [PDF] |
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I Stoykov, H C van Beeren, A F M Moorman, V M Christoffels, W M Wiersinga, and O Bakker Effect of amiodarone and dronedarone administration in rats on thyroid hormone-dependent gene expression in different cardiac components Eur. J. Endocrinol., June 1, 2007; 156(6): 695 - 702. [Abstract] [Full Text] [PDF] |
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D. D. Belke, B. Gloss, E. A. Swanson, and W. H. Dillmann Adeno-Associated Virus-Mediated Expression of Thyroid Hormone Receptor Isoforms-{alpha}1 and -{beta}1 Improves Contractile Function in Pressure Overload-Induced Cardiac Hypertrophy Endocrinology, June 1, 2007; 148(6): 2870 - 2877. [Abstract] [Full Text] [PDF] |
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E. van Rooij, L. B. Sutherland, X. Qi, J. A. Richardson, J. Hill, and E. N. Olson Control of Stress-Dependent Cardiac Growth and Gene Expression by a MicroRNA Science, April 27, 2007; 316(5824): 575 - 579. [Abstract] [Full Text] [PDF] |
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C. Pantos, I. Mourouzis, C. Xinaris, A. D Kokkinos, K. Markakis, A. Dimopoulos, M. Panagiotou, T. Saranteas, G. Kostopanagiotou, and D. V Cokkinos Time-dependent changes in the expression of thyroid hormone receptor {alpha}1 in the myocardium after acute myocardial infarction: possible implications in cardiac remodelling Eur. J. Endocrinol., April 1, 2007; 156(4): 415 - 424. [Abstract] [Full Text] [PDF] |
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M. Sakamoto, T. Minamino, H. Toko, Y. Kayama, Y. Zou, M. Sano, E. Takaki, T. Aoyagi, K. Tojo, N. Tajima, et al. Upregulation of Heat Shock Transcription Factor 1 Plays a Critical Role in Adaptive Cardiac Hypertrophy Circ. Res., December 8, 2006; 99(12): 1411 - 1418. [Abstract] [Full Text] [PDF] |
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C. C. Sucharov, P. D. Mariner, K. R. Nunley, C. Long, L. Leinwand, and M. R. Bristow A beta1-adrenergic receptor CaM kinase II-dependent pathway mediates cardiac myocyte fetal gene induction Am J Physiol Heart Circ Physiol, September 1, 2006; 291(3): H1299 - H1308. [Abstract] [Full Text] [PDF] |
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M. G. Trivieri, G. Y. Oudit, R. Sah, B.-G. Kerfant, H. Sun, A. O. Gramolini, Y. Pan, A. D. Wickenden, W. Croteau, G. Morreale de Escobar, et al. Cardiac-specific elevations in thyroid hormone enhance contractility and prevent pressure overload-induced cardiac dysfunction PNAS, April 11, 2006; 103(15): 6043 - 6048. [Abstract] [Full Text] [PDF] |
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A. Kenessey, E. A. Sullivan, and K. Ojamaa Nuclear localization of protein kinase C-{alpha} induces thyroid hormone receptor-{alpha}1 expression in the cardiomyocyte Am J Physiol Heart Circ Physiol, January 1, 2006; 290(1): H381 - H389. [Abstract] [Full Text] [PDF] |
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W. I. Khalife, Y.-D. Tang, J. A. Kuzman, T. A. Thomas, B. E. Anderson, S. Said, P. Tille, E. H. Schlenker, and A. M. Gerdes Treatment of subclinical hypothyroidism reverses ischemia and prevents myocyte loss and progressive LV dysfunction in hamsters with dilated cardiomyopathy Am J Physiol Heart Circ Physiol, December 1, 2005; 289(6): H2409 - H2415. [Abstract] [Full Text] [PDF] |
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Y.-D. Tang, J. A. Kuzman, S. Said, B. E. Anderson, X. Wang, and A. M. Gerdes Low Thyroid Function Leads to Cardiac Atrophy With Chamber Dilatation, Impaired Myocardial Blood Flow, Loss of Arterioles, and Severe Systolic Dysfunction Circulation, November 15, 2005; 112(20): 3122 - 3130. [Abstract] [Full Text] [PDF] |
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K. Kinugawa, M. Y. Jeong, M. R. Bristow, and C. S. Long Thyroid Hormone Induces Cardiac Myocyte Hypertrophy in a Thyroid Hormone Receptor {alpha}1-Specific Manner that Requires TAK1 and p38 Mitogen-Activated Protein Kinase Mol. Endocrinol., June 1, 2005; 19(6): 1618 - 1628. [Abstract] [Full Text] [PDF] |
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T. A. Thomas, J. A. Kuzman, B. E. Anderson, S. M. K. Andersen, E. H. Schlenker, M. S. Holder, and A. M. Gerdes Thyroid hormones induce unique and potentially beneficial changes in cardiac myocyte shape in hypertensive rats near heart failure Am J Physiol Heart Circ Physiol, May 1, 2005; 288(5): H2118 - H2122. [Abstract] [Full Text] [PDF] |
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M. Y. Jeong, K. Kinugawa, C. Vinson, and C. S. Long AFos Dissociates Cardiac Myocyte Hypertrophy and Expression of the Pathological Gene Program Circulation, April 5, 2005; 111(13): 1645 - 1651. [Abstract] [Full Text] [PDF] |
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S. W. Kong, N. Bodyak, P. Yue, Z. Liu, J. Brown, S. Izumo, and P. M. Kang Genetic expression profiles during physiological and pathological cardiac hypertrophy and heart failure in rats Physiol Genomics, March 21, 2005; 21(1): 34 - 42. [Abstract] [Full Text] [PDF] |
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M. Dorr, B. Wolff, D. M. Robinson, U. John, J. Ludemann, W. Meng, S. B. Felix, and H. Volzke The Association of Thyroid Function with Cardiac Mass and Left Ventricular Hypertrophy J. Clin. Endocrinol. Metab., February 1, 2005; 90(2): 673 - 677. [Abstract] [Full Text] [PDF] |
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A. Kenessey and K. Ojamaa Ligand-mediated decrease of thyroid hormone receptor-{alpha}1 in cardiomyocytes by proteosome-dependent degradation and altered mRNA stability Am J Physiol Heart Circ Physiol, February 1, 2005; 288(2): H813 - H821. [Abstract] [Full Text] [PDF] |
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B. C. Harrison, C. R. Roberts, D. B. Hood, M. Sweeney, J. M. Gould, E. W. Bush, and T. A. McKinsey The CRM1 Nuclear Export Receptor Controls Pathological Cardiac Gene Expression Mol. Cell. Biol., December 15, 2004; 24(24): 10636 - 10649. [Abstract] [Full Text] [PDF] |
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C. C. Sucharov, S. M. Helmke, S. J. Langer, M. B. Perryman, M. Bristow, and L. Leinwand The Ku Protein Complex Interacts with YY1, Is Up-Regulated in Human Heart Failure, and Represses {alpha} Myosin Heavy-Chain Gene Expression Mol. Cell. Biol., October 1, 2004; 24(19): 8705 - 8715. [Abstract] [Full Text] [PDF] |
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P. M. Kang, P. Yue, Z. Liu, O. Tarnavski, N. Bodyak, and S. Izumo Alterations in apoptosis regulatory factors during hypertrophy and heart failure Am J Physiol Heart Circ Physiol, July 1, 2004; 287(1): H72 - H80. [Abstract] [Full Text] [PDF] |
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E. S. Bachman, T. G. Hampton, H. Dhillon, I. Amende, J. Wang, J. P. Morgan, and A. N. Hollenberg The Metabolic and Cardiovascular Effects of Hyperthyroidism Are Largely Independent of {beta}-Adrenergic Stimulation Endocrinology, June 1, 2004; 145(6): 2767 - 2774. [Abstract] [Full Text] [PDF] |
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M. Iemitsu, T. Miyauchi, S. Maeda, T. Tanabe, M. Takanashi, M. Matsuda, and I. Yamaguchi Exercise training improves cardiac function-related gene levels through thyroid hormone receptor signaling in aged rats Am J Physiol Heart Circ Physiol, May 1, 2004; 286(5): H1696 - H1705. [Abstract] [Full Text] [PDF] |
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N. Frey, H. A. Katus, E. N. Olson, and J. A. Hill Hypertrophy of the Heart: A New Therapeutic Target? Circulation, April 6, 2004; 109(13): 1580 - 1589. [Abstract] [Full Text] [PDF] |
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T. M. Ortiga-Carvalho, K. Hashimoto, C. C. Pazos-Moura, D. Geenen, R. Cohen, R. M. Lang, and F. E. Wondisford Thyroid Hormone Resistance in the Heart: Role of the Thyroid Hormone Receptor {beta} Isoform Endocrinology, April 1, 2004; 145(4): 1625 - 1633. [Abstract] [Full Text] [PDF] |
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E. H. Schlenker, T. Tamura, and A. M. Gerdes Gender-specific effects of thyroid hormones on cardiopulmonary function in SHHF rats J Appl Physiol, December 1, 2003; 95(6): 2292 - 2298. [Abstract] [Full Text] |
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F. Liang, P. Webb, A. Marimuthu, S. Zhang, and D. G. Gardner Triiodothyronine Increases Brain Natriuretic Peptide (BNP) Gene Transcription and Amplifies Endothelin-dependent BNP Gene Transcription and Hypertrophy in Neonatal Rat Ventricular Myocytes J. Biol. Chem., April 18, 2003; 278(17): 15073 - 15083. [Abstract] [Full Text] [PDF] |
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H. Degens, A. J. Gilde, M. Lindhout, P. H. M. Willemsen, G. J. van der Vusse, and M. van Bilsen Functional and metabolic adaptation of the heart to prolonged thyroid hormone treatment Am J Physiol Heart Circ Physiol, January 1, 2003; 284(1): H108 - H115. [Abstract] [Full Text] [PDF] |
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R. E. Weiss, C. Korcarz, O. Chassande, K. Cua, P. M. Sadow, E. Koo, J. Samarut, and R. Lang Thyroid hormone and cardiac function in mice deficient in thyroid hormone receptor-alpha or -beta : an echocardiograph study Am J Physiol Endocrinol Metab, September 1, 2002; 283(3): E428 - E435. [Abstract] [Full Text] [PDF] |
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W. Lim and J. D. Furlow Ribozyme suppression of endogenous thyroid hormone receptor activity in Xenopus laevis cells Nucleic Acids Res., August 1, 2002; 30(15): 3490 - 3496. [Abstract] [Full Text] [PDF] |
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M. A. Sussman When the Thyroid Speaks, the Heart Listens Circ. Res., September 28, 2001; 89(7): 557 - 559. [Full Text] [PDF] |
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