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Yoshikawa M, Morifuji T, Matsumoto T, Maeshige N, Tanaka M, Fujino H. Effects of combined treatment with blood flow restriction and low-current electrical stimulation on muscle hypertrophy in rats. J Appl Physiol (1985) 2019; 127:1288-1296. [PMID: 31556832 DOI: 10.1152/japplphysiol.00070.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study aimed to clarify the effects of a combined treatment comprising blood flow restriction and low-current electrical stimulation on skeletal muscle hypertrophy in rats. Male Wistar rats were divided into control (Cont), blood flow restriction (Bfr), electrical stimulation (Es), or Bfr with Es (Bfr + Es) groups. Pressure cuffs (80 mmHg) were placed around the thighs of Bfr and Bfr + Es rats. Low-current Es was applied to calf muscles in the Es and Bfr + Es rats. In experiment 1, a 1-day treatment regimen (5-min stimulation, followed by 5-min rest) was delivered four times to study the acute effects. In experiment 2, the same treatment regimen was delivered three times/wk for 8 wk. Body weight, muscle mass, changes in maximal isometric contraction, fiber cross-sectional area of the soleus muscle, expression of phosphorylated and total-ERK1/2, phosphorylated-rpS6 Ser235/236, phosphorylated and total Akt, and phosphorylated-rpS6 Ser240/244 were measured. Bfr and Es treatment alone failed to induce muscle hypertrophy and increase the expression of phosphorylated rpS6 Ser240/244. Combined Bfr + Es upregulated muscle mass, increased the fiber cross-sectional area, and increased phosphorylated rpS6 Ser240/244 expression and phosphorylated rpS6 Ser235/236 expression compared with controls. Combined treatment with Bfr and low-current Es can induce muscle hypertrophy via activation of two protein synthesis signaling pathways. This treatment should be introduced for older patients with sarcopenia and others with muscle weakness.NEW & NOTEWORTHY We investigated the acute and chronic effect of low-current electrical stimulation with blood flow restriction on skeletal muscle hypertrophy and the mechanisms controlling the hypertrophic response. Low-current electrical stimulation could not induce skeletal muscle hypertrophy, but a combination treatment did. Blood lactate and growth hormone levels were increased in the early response. Moreover, activation of ERK1/2 and mTOR pathways were observed in both the acute and chronic response, which contribute to muscle hypertrophy.
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Affiliation(s)
- Madoka Yoshikawa
- Department of Rehabilitation Science, Kobe University Graduate School of Health Science, Kobe, Japan
| | - Takeshi Morifuji
- Department of Rehabilitation Science, Kobe University Graduate School of Health Science, Kobe, Japan.,Department of Rehabilitation Science, Osaka Kawasaki Rehabilitation University, Kaizuka, Japan
| | - Tomohiro Matsumoto
- Department of Rehabilitation Science, Kobe University Graduate School of Health Science, Kobe, Japan
| | - Noriaki Maeshige
- Department of Rehabilitation Science, Kobe University Graduate School of Health Science, Kobe, Japan
| | - Minoru Tanaka
- Department of Rehabilitation Science, Kobe University Graduate School of Health Science, Kobe, Japan.,Department of Rehabilitation Science, Osaka Health Science University, Osaka, Japan
| | - Hidemi Fujino
- Department of Rehabilitation Science, Kobe University Graduate School of Health Science, Kobe, Japan
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Tanaka M, Morifuji T, Yoshikawa M, Nakanishi R, Fujino H. Effects of combined treatment with blood flow restriction and low-intensity electrical stimulation on diabetes mellitus-associated muscle atrophy in rats. J Diabetes 2019; 11:326-334. [PMID: 30225988 DOI: 10.1111/1753-0407.12857] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 08/12/2018] [Accepted: 09/10/2018] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Diabetes mellitus (DM) results in decreased muscle mass and harmful complications. Blood flow restriction (Bfr) and electrical stimulation (ES) increase muscle protein synthesis. We hypothesized that combined Bfr and low-intensity ES may be more effective in preventing diabetes-associated muscle atrophy by inhibiting the downregulation of protein synthesis-related pathways. In this study, the effects of combined Bfr and low-intensity ES on diabetes-associated muscle atrophy were investigated by evaluating advanced glycation end-products (AGEs) and receptor for AGEs (RAGE) in rats. METHODS Twenty-four Goto-Kakizaki (GK) rats were randomly divided into four treatment groups: sedentary DM, DM + Bfr (pressure cuffs placed around the thigh), DM + ES, and DM + Bfr + ES. Six Wistar rats were used as an age-matched control. Levels of AGEs and the expression of RAGE, extracellular signal-regulated kinase (ERK), and ribosomal protein S6 (rpS6) were determined in plantaris muscles. RESULTS Diabetes resulted in a loss of muscle mass and upregulation of AGEs and RAGE in the plantaris muscle compared with the control group. Treatment with Bfr and ES alone failed to attenuate diabetes-associated loss of muscle mass, and could not prevent the upregulation of AGEs. However, the combination of Bfr and ES prevented the diabetes-associated decrease in muscle mass and upregulation of AGEs. In addition, the combination treatment prevented diabetes-associated decreases in the expression of phosphorylated rpS6. CONCLUSIONS Combination treatment with Bfr and ES may prevent diabetes-associated muscle atrophy by upregulating inhibition of AGEs, which leads to the activation of protein synthesis.
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Affiliation(s)
- Minoru Tanaka
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan
- Department of Rehabilitation Science, Osaka Health Science University, Osaka, Japan
| | - Takeshi Morifuji
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan
- Department of Rehabilitation, Osaka Kawasaki Rehabilitation University, Kaizuka, Japan
| | - Madoka Yoshikawa
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan
| | - Ryosuke Nakanishi
- Department of Rehabilitation, Kobe International University, Kobe, Japan
| | - Hidemi Fujino
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan
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Ramos FJ, Chen SC, Garelick MG, Dai DF, Liao CY, Schreiber KH, MacKay VL, An EH, Strong R, Ladiges WC, Rabinovitch PS, Kaeberlein M, Kennedy BK. Rapamycin reverses elevated mTORC1 signaling in lamin A/C-deficient mice, rescues cardiac and skeletal muscle function, and extends survival. Sci Transl Med 2012; 4:144ra103. [PMID: 22837538 DOI: 10.1126/scitranslmed.3003802] [Citation(s) in RCA: 261] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Mutations in LMNA, the gene that encodes A-type lamins, cause multiple diseases including dystrophies of the skeletal muscle and fat, dilated cardiomyopathy, and progeria-like syndromes (collectively termed laminopathies). Reduced A-type lamin function, however, is most commonly associated with skeletal muscle dystrophy and dilated cardiomyopathy rather than lipodystrophy or progeria. The mechanisms underlying these diseases are only beginning to be unraveled. We report that mice deficient in Lmna, which corresponds to the human gene LMNA, have enhanced mTORC1 (mammalian target of rapamycin complex 1) signaling specifically in tissues linked to pathology, namely, cardiac and skeletal muscle. Pharmacologic reversal of elevated mTORC1 signaling by rapamycin improves cardiac and skeletal muscle function and enhances survival in mice lacking A-type lamins. At the cellular level, rapamycin decreases the number of myocytes with abnormal desmin accumulation and decreases the amount of desmin in both muscle and cardiac tissue of Lmna(-/-) mice. In addition, inhibition of mTORC1 signaling with rapamycin improves defective autophagic-mediated degradation in Lmna(-/-) mice. Together, these findings point to aberrant mTORC1 signaling as a mechanistic component of laminopathies associated with reduced A-type lamin function and offer a potential therapeutic approach, namely, the use of rapamycin-related mTORC1 inhibitors.
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Affiliation(s)
- Fresnida J Ramos
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
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Jiang ZS, Wen GB, Tang ZH, Srisakuldee W, Fandrich RR, Kardami E. High molecular weight FGF-2 promotes postconditioning-like cardioprotection linked to activation of protein kinase C isoforms, as well as Akt and p70 S6 kinases. [corrected]. Can J Physiol Pharmacol 2010; 87:798-804. [PMID: 19898562 DOI: 10.1139/y09-049] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fibroblast growth factor 2 (FGF-2) is a multifunctional protein translated as high and low molecular weight isoforms (hi- and lo-FGF-2, respectively). Although the postconditioning cardioprotective effect of lo-FGF-2 (18 kDa) has been documented, hi-FGF-2 is less well studied. We used an isolated perfused rat heart model of ischemia-reperfusion to study the effects of postischemic (during reperfusion) administration of hi-FGF-2 on recovery of contractile function and tissue salvage, as indicated by decreased cytosolic cytochrome c levels. Compared with the vehicle-treated group, hi-FGF-2-treated hearts had significantly improved recovery of systolic pressure, developed pressure, rates of contraction and relaxation, and coronary flow, as well as decreased relative levels of cytosolic cytochrome c. The effects of hi-FGF-2 on functional recovery and cytosolic cytochrome c were indistinguishable from those induced by lo-FGF-2. Both hi- and lo-FGF-2 upregulated relative levels of phosphorylated (activated) Akt and p70 S6 kinase, and they both promoted translocation of alpha, epsilon, and zeta isoforms of protein kinase C (PKC) to the particulate fraction of reperfused hearts. The magnitude of the effect on PKCzeta and p70 S6 kinases, however, was significantly more potent in the hi-FGF-2 than in the lo-FGF-2 group. We conclude that acute postischemic cardioprotection by hi- or lo-FGF-2 is isoform nonspecific and likely to be mediated by PKC and Akt. Nevertheless, isoform-specific functions are suggested by the augmented sensitivity of p70 S6 and PKCzeta to hi-FGF-2.
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Affiliation(s)
- Zhi-Sheng Jiang
- Institute of Cardiovascular Disease and Key Laboratory for Arteriosclerology of Hunan Province, Hengyang City, Hunan 421001, PR China
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PGF2alpha-associated vascular smooth muscle hypertrophy is ROS dependent and involves the activation of mTOR, p70S6k, and PTEN. Prostaglandins Other Lipid Mediat 2007; 85:49-57. [PMID: 18160324 DOI: 10.1016/j.prostaglandins.2007.10.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2006] [Revised: 07/12/2007] [Accepted: 10/26/2007] [Indexed: 11/23/2022]
Abstract
Prostaglandin F2alpha (PGF2alpha) increases reactive oxygen species (ROS) and induces vascular smooth muscle cell (VSMC) hypertrophy by largely unknown mechanism(s). To investigate the signaling events governing PGF2alpha-induced VSMC hypertrophy we examined the ability of the PGF2alpha analog, fluprostenol to elicit phosphorylation of Akt, the mammalian target of rapamycin (mTOR), ribosomal protein S6 kinase (p70S6k), glycogen synthase kinase-3beta (GSK-3beta), phosphatase and tensin homolog (PTEN), extracellular signal-regulated kinase 1/2 (ERK1/2) and Jun N-terminal kinase (JNK) in growth arrested A7r5 VSMC. Fluprostenol-induced hypertrophy was associated with increased ROS, mTOR translocation from the nucleus to the cytoplasm, along with Akt, mTOR, GSK-3beta, PTEN and ERK1/2 but not JNK phosphorylation. Whereas inhibition of phosphatidylinositol 3-kinase (PI3K) by LY-294002 blocked fluprostenol-induced changes in total protein content, pre-treatment with rapamycin or with the MEK1/2 inhibitor U0126 did not. Taken together, these findings suggest that fluprostenol-induced changes in A7r5 hypertrophy involve mTOR translocation and occur through PI3K-dependent mechanisms.
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Crossno JT, Garat CV, Reusch JEB, Morris KG, Dempsey EC, McMurtry IF, Stenmark KR, Klemm DJ. Rosiglitazone attenuates hypoxia-induced pulmonary arterial remodeling. Am J Physiol Lung Cell Mol Physiol 2007; 292:L885-97. [PMID: 17189321 DOI: 10.1152/ajplung.00258.2006] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Thiazolidinediones (TZDs) are insulin-sensitizing agents that also decrease systemic blood pressure, attenuate the formation of atherosclerotic lesions, and block remodeling of injured arterial walls. Recently, TZDs were shown to prevent pulmonary arterial (PA) remodeling in rats treated with monocrotaline. Presently we report studies testing the ability of the TZD rosiglitazone (ROSI) to attenuate pathological arterial remodeling in the lung and prevent the development of pulmonary hypertension (PH) in rats subjected to chronic hypoxia. PA remodeling was reduced in ROSI-treated animals exposed to hypoxia compared with animals exposed to hypoxia alone. ROSI treatment blocked muscularization of distal pulmonary arterioles and reversed remodeling and neomuscularization in lungs of animals previously exposed to chronic hypoxia. Decreased PA remodeling in ROSI-treated animals was associated with decreased smooth muscle cell proliferation, decreased collagen and elastin deposition, and increased matrix metalloproteinase-2 activity in the PA wall. Cells expressing the c-Kit cell surface marker were observed in the PA adventitia of untreated animals exposed to hypoxia but not in ROSI-treated hypoxic rats. Right ventricular hypertrophy and cardiomyocyte hypertrophy were also blunted in ROSI-treated hypoxic animals. Interestingly, mean PA pressures were elevated equally in the untreated and ROSI-treated groups, indicating that ROSI had no effect on the development of PH. However, mean PA pressure was normalized acutely in both groups of hypoxia-exposed animals by Fasudil, an agent that inhibits RhoA/Rho kinase-mediated vasoconstriction. We conclude that ROSI can attenuate and reverse PA remodeling and neomuscularization associated with hypoxic PH. However, this agent fails to block the development of PH, apparently because of its inability to repress sustained Rho kinase-mediated arterial vasoconstriction.
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Affiliation(s)
- Joseph T Crossno
- Pulmonary and Critical Care Services, Veterans Affairs Medical Center, Denver, USA
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Samuelsson AM, Bollano E, Mobini R, Larsson BM, Omerovic E, Fu M, Waagstein F, Holmäng A. Hyperinsulinemia: effect on cardiac mass/function, angiotensin II receptor expression, and insulin signaling pathways. Am J Physiol Heart Circ Physiol 2006; 291:H787-96. [PMID: 16565309 DOI: 10.1152/ajpheart.00974.2005] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
To investigate the association between hyperinsulinemia and cardiac hypertrophy, we treated rats with insulin for 7 wk and assessed effects on myocardial growth, vascularization, and fibrosis in relation to the expression of angiotensin II receptors (AT-R). We also characterized insulin signaling pathways believed to promote myocyte growth and interact with proliferative responses mediated by G protein-coupled receptors, and we assessed myocardial insulin receptor substrate-1 (IRS-1) and p110 alpha catalytic and p85 regulatory subunits of phospatidylinositol 3 kinase (PI3K), Akt, MEK, ERK1/2, and S6 kinase-1 (S6K1). Left ventricular (LV) geometry and performance were evaluated echocardiographically. Insulin decreased AT1a-R mRNA expression but increased protein levels and increased AT2-R mRNA and protein levels and phosphorylation of IRS-1 (Ser374/Tyr989), MEK1/2 (Ser218/Ser222), ERK1/2 (Thr202/Tyr204), S6K1 (Thr421/Ser424/Thr389), Akt (Thr308/Thr308), and PI3K p110 alpha but not of p85 (Tyr508). Insulin increased LV mass and relative wall thickness and reduced stroke volume and cardiac output. Histochemical examination demonstrated myocyte hypertrophy and increases in interstitial fibrosis. Metoprolol plus insulin prevented the increase in relative wall thickness, decreased fibrosis, increased LV mass, and improved function seen with insulin alone. Thus our data demonstrate that chronic hyperinsulinemia decreases AT1a-to-AT2 ratio and increases MEK-ERK1/2 and S6K1 pathway activity related to hypertrophy. These changes might be crucial for increased cardiovascular growth and fibrosis and signs of impaired LV function.
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Affiliation(s)
- Anne-Maj Samuelsson
- Cardiovascular Institute, The Wallenberg Laboratory, Sahlgrenska Univ. Hospital, Göteborg University, S-413 45 Göteborg, Sweden.
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Xia Y, Karmazyn M. Obligatory role for endogenous endothelin in mediating the hypertrophic effects of phenylephrine and angiotensin II in neonatal rat ventricular myocytes: evidence for two distinct mechanisms for endothelin regulation. J Pharmacol Exp Ther 2004; 310:43-51. [PMID: 15007106 DOI: 10.1124/jpet.104.065185] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Various Gq protein-coupled receptor agonists such as the alpha1 adrenoceptor agonist phenylephrine, angiotensin II, and endothelin-1 are potent hypertrophic factors. There is evidence of potential cross talk between these agents, particularly in terms of endothelin-1 as playing a central role in mediating the actions of other hypertrophic factors. Using cultured rat neonatal ventricular myocytes, we assessed the potential cross talk between these factors and sought to examine the potential underlying mechanisms. Twenty-four-hour exposure to either agent produced significant hypertrophy as determined by cell size and molecular markers. Although the hypertrophic effects of phenylephrine and angiotensin II were expectedly prevented by alpha1 and AT1 receptor antagonists, respectively, these effects were also blocked by the ETA receptor antagonist BQ123 [cyclo(D-Asp-Pro-D-Val-Leu-D-Trp)] but not by the ETB antagonist BQ788 (N-cis-2,6-dimethylpiperidinocarbonyl-L-gamma-methylleucyl-D-1-methoxycarbonyltryptophanyl-D-norleucine). Both phenylephrine and angiotensin II significantly increased protein expression of both endothelin receptor subtypes. Both phenylephrine and angiotensin II produced significant activation of p38 as well as extracellular signal-regulated protein kinase and c-Jun NH2-terminal kinase, although this was unaffected by endothelin receptor blockade. Further studies revealed that the effects of phenylephrine and angiotensin II were mediated by stimulated endothelin-1 production occurring via two separate mechanisms: angiotensin II by increasing the levels of the endothelin-1 precursor prepro endothelin-1 and phenylephrine by upregulating endothelin-converting enzyme 1. Our results indicate that the endothelin-1 system plays an obligatory role in the hypertrophic response to both phenylephrine and angiotensin II in cultured myocytes through a mechanism independent of mitogenactivated protein kinase activation.
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Affiliation(s)
- Ying Xia
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
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Abstract
Cardiac hypertrophy is the heart's response to a variety of extrinsic and intrinsic stimuli that impose increased biomechanical stress. While hypertrophy can eventually normalize wall tension, it is associated with an unfavorable outcome and threatens affected patients with sudden death or progression to overt heart failure. Accumulating evidence from studies in human patients and animal models suggests that in most instances hypertrophy is not a compensatory response to the change in mechanical load, but rather is a maladaptive process. Accordingly, modulation of myocardial growth without adversely affecting contractile function is increasingly recognized as a potentially auspicious approach in the prevention and treatment of heart failure. In this review, we summarize recent insights into hypertrophic signaling and consider several novel antihypertrophic strategies.
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Affiliation(s)
- N Frey
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA.
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Ozaki M, Kawashima S, Yamashita T, Hirase T, Ohashi Y, Inoue N, Hirata KI, Yokoyama M. Overexpression of endothelial nitric oxide synthase attenuates cardiac hypertrophy induced by chronic isoproterenol infusion. Circ J 2002; 66:851-6. [PMID: 12224825 DOI: 10.1253/circj.66.851] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Endogenous nitric oxide (NO) inhibits the contractile response to beta-adrenergic stimulation, but its effect on cardiac hypertrophy mediated by beta-adrenoceptors remains unclear. The present study was designed to determine whether overproduction of endothelial NO synthase (eNOS) could inhibit cardiac hypertrophy induced by chronic isoproterenol (ISO) infusion (30mg/kg per day) using eNOS overexpressing (eNOS-Tg) mice and wild-type (WT) mice. In a separate group, WT mice were treated with ISO and hydralazine to decrease blood pressure to the same levels in eNOS-Tg mice. The eNOS expression, NOS activity, and cGMP levels in the heart were remarkably higher in eNOS-Tg mice than in WT mice. ISO increased both heart weight and the heart/body weight ratio, which were significantly attenuated in eNOS-Tg mice compared with WT or hydralazine-treated WT mice. Histological examination revealed that the extent of fibrosis was not significantly different among the 3 groups, and that the increase in myocyte size was more than 10% lower in eNOS-Tg than in the other groups. In addition, up-regulated expression of atrial natriuretic peptide mRNA associated with cardiac hypertrophy was significantly inhibited in eNOS-Tg mice during ISO infusion. These results indicate that endogenous NO might act as a negative modulator for the hypertrophic response to beta-adrenergic stimulation.
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Affiliation(s)
- Masanori Ozaki
- Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
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Tamamori-Adachi M, Ito H, Nobori K, Hayashida K, Kawauchi J, Adachi S, Ikeda MA, Kitajima S. Expression of cyclin D1 and CDK4 causes hypertrophic growth of cardiomyocytes in culture: a possible implication for cardiac hypertrophy. Biochem Biophys Res Commun 2002; 296:274-80. [PMID: 12163013 DOI: 10.1016/s0006-291x(02)00854-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Differentiated cardiomyocytes have little capacity to proliferate and show the hypertrophic growth in response to alpha1-adrenergic stimuli via the Ras/MEK pathway. In this study, we investigated a role of cyclin D1 and CDK4, a positive regulator of cell cycle, in cultured neonatal rat cardiomyocyte hypertrophy. D-type cyclins including cyclin D1 were induced in cells stimulated by phenylephrine. This induction was inhibited by MEK inhibitor PD98059 and the dominant negative RasN17, but mimicked by expression of the constitutive active Ras61L. Over-expression of cyclin D1 and CDK4 using adenovirus gene transfer caused the hypertrophic growth of cardiomyocytes, as evidenced by an increase of the cell size as well as the amount of cellular protein and its rate of synthesis. However, the cyclin D1/CDK4 kinase activity was not up-regulated in cells treated by hypertrophic stimuli or in cells over-expressing the cyclin D1 and CDK4. Furthermore, a CDK inhibitor, p16, did not inhibit the hypertrophic growth of cardiomyocytes. These results clearly indicated that cyclin D1 and CDK4 have a role in hypertrophic growth of cardiomyocytes through a novel mechanism(s) which appears not to be related to its activity required for cell cycle progression.
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Affiliation(s)
- Mimi Tamamori-Adachi
- Department of Biochemical Genetics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan.
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Mocanu MM, Bell RM, Yellon DM. PI3 kinase and not p42/p44 appears to be implicated in the protection conferred by ischemic preconditioning. J Mol Cell Cardiol 2002; 34:661-8. [PMID: 12054853 DOI: 10.1006/jmcc.2002.2006] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ischemic preconditioning results in an immediate phase of protection against lethal ischemia/reperfusion injury that is comprised of both irreversible necrosis and programmed cell death, apoptosis. We hypothesized that preconditioning may activate putative anti-apoptotic pathways, through the induction of either phosphatidyl inositol 3-OH kinase (PI3 kinase) or p42/p44 extracellular receptor kinase, attenuating total cell death. Isolated perfused rat hearts were preconditioned with two cycles of 5 min ischemia and 10 min reperfusion. Then they were frozen for Western blot analysis or subjected to 35 min regional ischemia and 120 min reperfusion prior to infarct size assessment. Selective PI3 kinase inhibitors, wortmannin (W, 100 n M) and LY294002 (LY, 15 microM) and the p42/p44 inhibitor, PD 98059 (PD, 10 and 50 microM), were individually infused during the preconditioning protocol. One further group of hearts received both inhibitors (W and PD). The results were expressed as percentage of infarction within the risk zone. Inhibition of PI3 kinase by either W or LY partially abrogated the infarct sparing effect of ischemic preconditioning (I/R%: 44.6+/-2.7 in C, 17.6+/-2.0 in IP, vs 32.2+/-4.2 in W, and 30.9+/-2.6 in LY, P<0.05). Inhibition of ERK phosphorylation however, had no significant effect upon infarct size reduction (17.6+/-2.0 in ischemic preconditioning vs 21.4+/-3.0 in IP+10 microM PD and 15.2+/-1.4 in IP+50 microM PD, P>0.05). Western blot analysis confirmed that PD abrogated the phosphorylation of p42/p44 and LY the phosphorylation of AKT. Combined inhibition with PD+W failed to further attenuate protection (27.6+/-1.3%, P>0.1). These data appear to demonstrate that the PI3 kinase, but not the p42/p44 cascade, is implicated in early ischemic preconditioning.
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Affiliation(s)
- Mihaela M Mocanu
- The Hatter Institute for Cardiovascular Studies, University College London Hospital and Medical School, London, UK
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Kahan BD. The limitations of calcineurin and mTOR inhibitors: new directions for immunosuppressive strategies. Transplant Proc 2002; 34:130-3. [PMID: 11959221 DOI: 10.1016/s0041-1345(01)02702-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- B D Kahan
- Division of Organ Transplantation, Department of Surgery, The University of Texas Medical School, Houston, Texas 77030, USA
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