cyclin-d1 and Hypertrophy

Nuclear receptor pregnane X receptor (PXR) can induce significant liver enlargement through hepatocyte hypertrophy and proliferation. A previous report showed that during the process of PXR-induced liver enlargement, hepatocyte hypertrophy occurs around the central vein (CV) area while hepatocyte proliferation occurs around the portal vein (PV) area. However, the features of this spatial change remain unclear. Therefore, this study aims to explore the features of the spatial changes in hepatocytes in PXR-induced liver enlargement. PXR-induced spatial changes in hepatocyte hypertrophy and proliferation were confirmed in C57BL/6 mice. The liver was perfused with digitonin to destroy the hepatocytes around the CV or PV areas, and then the regional expression of proteins related to hepatocyte hypertrophy and proliferation was further measured. The results showed that the expression of PXR downstream proteins, such as cytochrome P450 (CYP) 3A11, CYP2B10, P-glycoprotein (P-gp) and organ anion transporting polypeptide 4 (OATP4) was upregulated around the CV area, while the expression of proliferation-related proteins such as cyclin B1 (CCNB1), cyclin D1 (CCND1) and serine/threonine NIMA-related kinase 2 (NEK2) was upregulated around the PV area. At the same time, the expression of cyclin-dependent kinase inhibitors such as retinoblastoma-like protein 2 (RBL2), cyclin-dependent kinase inhibitor 1B (CDKN1B) and CDKN1A was downregulated around the PV area. This study demonstrated that the spatial change in PXR-induced hepatocyte hypertrophy and proliferation is associated with the regional expression of PXR downstream targets and proliferation-related proteins and the regional distribution of triglycerides (TGs). These findings provide new insight into the understanding of PXR-induced hepatomegaly.

Topics: Animals; Anions; ATP Binding Cassette Transporter, Subfamily B; Cell Proliferation; Cyclin B1; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p27; Cyclin-Dependent Kinases; Cytochrome P-450 CYP3A; Cytochrome P-450 Enzyme System; Digitonin; Hepatocytes; Hepatomegaly; Hypertrophy; Liver; Mice; Mice, Inbred C57BL; NIMA-Related Kinases; Pregnane X Receptor; Receptors, Cytoplasmic and Nuclear; Receptors, Steroid; Retinoblastoma-Like Protein p130; Serine; Threonine; Triglycerides

Adult hearts respond to increased workload such as prolonged stress or injury, by undergoing hypertrophic growth. During this process, the early adaptive responses are important for maintaining cardiac output whereas at later stages, pathological responses such as cardiomyocyte apoptosis and fibrosis cause adverse remodelling, that can progress to heart failure. Yet the factors that control transition from adaptive responses to pathological remodelling in the heart are not well understood. Here we describe the POU4F2/Brn-3b transcription factor (TF) as a novel regulator of adaptive hypertrophic responses in adult hearts since Brn-3b mRNA and protein are increased in angiotensin-II (AngII) treated mouse hearts with concomitant hypertrophic changes [increased heart weight:body weight (HW:BW) ratio]. These effects occur specifically in cardiomyocytes because Brn-3b expression is increased in AngII-treated primary cultures of neonatal rat ventricular myocytes (NRVM) or foetal heart-derived H9c2 cells, which undergo characteristic sarcomeric re-organisation seen in hypertrophic myocytes and express hypertrophic markers, ANP/βMHC. The Brn-3b promoter is activated by known hypertrophic signalling pathways e.g. p42/p44 mitogen-activated protein kinase (MAPK/ERK1/2) or calcineurin (via NFAT). Brn-3b target genes, e.g. cyclin D1, GLUT4 and Bax, are increased at different stages following AngII treatment, supporting distinct roles in cardiac responses to stress. Furthermore, hearts from male Brn-3b KO mutant mice display contractile dysfunction at baseline but also attenuated hypertrophic responses to AngII treatment. Hearts from AngII-treated male Brn-3b KO mice develop further contractile dysfunction linked to extensive fibrosis/remodelling. Moreover, known Brn-3b target genes, e.g. GLUT4, are reduced in AngII-treated Brn-3b KO hearts, suggesting that Brn-3b and its target genes are important in driving adaptive hypertrophic responses in stressed heart.

Topics: Angiotensin II; Animals; Animals, Newborn; Apoptosis; bcl-2-Associated X Protein; Calcineurin; Cardiovascular Diseases; Cyclin D1; Gene Expression Regulation; Glucose Transporter Type 4; Humans; Hypertrophy; Mice; Mice, Knockout; Myocardium; Myocytes, Cardiac; Primary Cell Culture; Rats; RNA, Small Interfering; Transcription Factor Brn-3B

The eukaryotic initiation factor 4E (eIF4E) is a major mRNA cap-binding protein that has a central role in translation initiation. Ser

Topics: Animals; Biomechanical Phenomena; Cyclin D1; Eukaryotic Initiation Factor-4E; Female; Gene Expression Regulation; Gene Knock-In Techniques; Hypertrophy; Male; Mice; Mice, Inbred C57BL; Muscle, Skeletal; Nuclear Proteins; Organelle Biogenesis; Phosphorylation; Protein Biosynthesis; Proto-Oncogene Proteins c-myc; Ribosomes; RNA, Ribosomal; Serine; Signal Transduction

The nuclear receptor (FXR) plays essential roles in maintaining bile acid and lipid homeostasis by regulating diverse target genes. And its agonists were promising agents for treating various liver diseases. Nevertheless, the potential side effect of chronic FXR activation by specific agonists is not fully understood. In this study, we investigated the mechanism of FXR agonist WAY-362450 induced liver enlargement during treating liver diseases. We demonstrated that chronic ingestion of WAY-362450 induced liver hypertrophy instead of hyperplasia in mouse. Global transcriptional pattern was also examined in mouse livers after treatment with WAY-362450 by RNA-seq assay. Through GO and KEGG enrichment analyses, we demonstrated that the expression of Cyclin D1 (

Topics: Acetylation; Animals; Azepines; Chromatin Immunoprecipitation; Computational Biology; Cyclin D1; Female; Gene Expression Regulation; Gene Ontology; Hep G2 Cells; Hepatocytes; Histones; Humans; Hypertrophy; Indoles; Liver; Male; Mice; Mice, Inbred C57BL; Protein Binding; Receptors, Cytoplasmic and Nuclear; RNA-Seq; Time Factors; Transcriptional Activation

Our previous study showed that WNT5A, a member of the noncanonical WNT pathway, is involved in interleukin-1beta induced matrix metalloproteinase expression in temporomandibular joint (TMJ) condylar chondrocytes. The purpose of this study is to further explore the roles of WNT5A in cartilage biology of the TMJ.. An early TMJ osteoarthritis-like rat model was constructed by a mechanical method (steady mouth-opening). The gene and protein levels of WNT5A during the condylar cartilage changes were measured. Effects of WNT5A on chondrocyte proliferation, hypertrophy and migration were analyzed after WNT5A gain or loss of function in vitro. A c-Jun N-terminal kinase (JNK) inhibitor SP600125 was used to evaluate the involvement of JNK pathway in these effects of WNT5A. The expression and transcription activity of cell cycle regulators c-MYC and Cyclin D1 were examined to determine the mechanism behind WNT5A regulation of chondrocyte proliferation.. WNT5A was significantly upregulated in the condylar cartilage of rats in the early TMJ osteoarthritis-like model. Activating WNT5A facilitated condylar chondrocyte proliferation, hypertrophy and migration. Conversely, inhibiting WNT5A activity in chondrocytes decreased their proliferation, hypertrophy and migration. Blockage of the JNK pathway by its inhibitor, SP600125, impaired these effects of WNT5A on chondrocytes. WNT5A regulated both the expression and transcriptional activity of c-MYC and Cyclin D1 in chondrocytes, both of which were upregulated in condylar cartilage of the rat early TMJ osteoarthritis.. WNT5A regulates condylar chondrocyte proliferation, hypertrophy and migration. These findings provide new insights into the role of WNT5A signaling in TMJ cartilage biology and its potential in future therapy for TMJ degenerative diseases.

Topics: Animals; Cell Movement; Cell Proliferation; Chondrocytes; Cyclin D1; Disease Models, Animal; Hypertrophy; Mandibular Condyle; Proto-Oncogene Proteins c-myc; Rats; Rats, Sprague-Dawley; Signal Transduction; Temporomandibular Joint Disorders; Up-Regulation; Wnt-5a Protein

Renal compensatory hypertrophy (RCH) restores normal kidney function after disease or loss of kidney tissue and is characterized by an increase in organ size due to cell enlargement and not to cell proliferation. In MDCK renal epithelial cells, silencing of the tight junction protein zona occludens 2 (ZO-2 KD) induces cell hypertrophy by two mechanisms: prolonging the time that cells spend at the G1 phase of the cell cycle due to an increase in cyclin D1 level, and augmenting the rate of protein synthesis. The latter is triggered by the nuclear accumulation and increased transcriptional activity of Yes-associated protein (YAP), the main target of the Hippo pathway, which results in decreased expression of phosphatase and tensin homologue. This in turn increased the level of phosphatidylinositol (3,4,5)-triphosphate, which transactivates the Akt/mammalian target of rapamycin pathway, leading to activation of the kinase S6K1 and increased synthesis of proteins and cell size. In agreement, in a rat model of uninephrectomy, RCH is accompanied by decreased expression of ZO-2 and nuclear expression of YAP. Our results reveal a novel role of ZO-2 as a modulator of cell size.

Topics: Adaptor Proteins, Signal Transducing; Animals; Cell Division; Cell Enlargement; Cell Proliferation; Cyclin D1; Dogs; G1 Phase; Hypertrophy; Madin Darby Canine Kidney Cells; Male; Phosphoproteins; PTEN Phosphohydrolase; Rats; Rats, Wistar; Signal Transduction; TOR Serine-Threonine Kinases; Transcription Factors; YAP-Signaling Proteins; Zonula Occludens-2 Protein

The molecular mechanism underlying renal hypertrophy and progressive nephron damage remains poorly understood. Here we generated congenic ribosomal protein S6 (rpS6) knock-in mice expressing nonphosphorylatable rpS6 and found that uninephrectomy-induced renal hypertrophy was significantly blunted in these knock-in mice. Uninephrectomy-induced increases in cyclin D1 and decreases in cyclin E in the remaining kidney were attenuated in the knock-in mice compared with their wild-type littermates. Uninephrectomy induced rpS6 phosphorylation in the wild-type mice; however, no rpS6 phosphorylation was detected in uninephrectomized or sham-operated knock-in mice. Nonetheless, uninephrectomy stimulated comparable 4E-BP1 phosphorylation in both knock-in and wild-type mice, indicating that mTORC1 was still activated in the knock-in mice. Moreover, the mTORC1 inhibitor rapamycin prevented both rpS6 and 4E-BP1 phosphorylation, significantly blunted uninephrectomy-induced renal hypertrophy in wild-type mice, but did not prevent residual renal hypertrophy despite inhibiting 4E-BP1 phosphorylation in uninephrectomized knock-in mice. Thus, both genetic and pharmacological approaches unequivocally demonstrate that phosphorylated rpS6 is a downstream effector of the mTORC1-S6K1 signaling pathway mediating renal hypertrophy. Hence, rpS6 phosphorylation facilitates the increase in cyclin D1 and decrease in cyclin E1 that underlie the hypertrophic nature of uninephrectomy-induced kidney growth.

Topics: Adaptor Proteins, Signal Transducing; Animals; Carrier Proteins; Cell Cycle Proteins; Cyclin D1; Cyclin E; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase 4; Eukaryotic Initiation Factors; Female; Gene Knock-In Techniques; Hypertrophy; Kidney; Male; Mechanistic Target of Rapamycin Complex 1; Mice; Multiprotein Complexes; Nephrectomy; Oncogene Proteins; Phosphoproteins; Phosphorylation; Ribosomal Protein S6; Ribosomal Protein S6 Kinases, 90-kDa; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases

The present study investigated the role of epidermal stem cell-expressed microRNA let-7b in the pathogenesis of hypertrophied anal papillae. Hypertrophied anal papillae were examined for the presence of epidermal stem cells. Epidermal stem cells were identified using flow cytometry and immunofluorescent staining for the cell surface markers, integrin α6 and integrin β1 subunits. Expression levels of microRNA let‑7b in α6+/β1+and α6‑/β1‑cells were compared using reverse transcription‑quantitative polymerase chain reaction and northern blotting. Lentivirus‑mediated expression of microRNA let‑7b in epidermal stem cells was utilized in order to study the effects of this microRNA on the cell cycle proteins, cyclin D1 (CCND1) and cyclin‑dependent kinase 4 (CDK4). MicroRNA let‑7b‑overexpressing cells were examined using flow cytometry, in order to determine the effects of the microRNA on cell cycle progression. α6+/β1+epidermal stem cells were identified in hypertrophic anal papillae. Following isolation and enrichment of the α6+/β1+population, these cells were found to have a rapid rate of proliferation in vitro. The expression of cell cycle‑related proteins was elevated in this population, compared with that in α6‑/β1‑cells. The expression of microRNA let‑7b in α6+/β1+epidermal stem cells was significantly lower than that in α6‑/β1‑cells. Two microRNA let‑7b target genes, CCND1 and CDK4, were found to be upregulated in α6+/β1+cells. When the exogenous precursor, microRNA let‑7, was overexpressed in α6+/β1+ epidermal stem cells, the cell proliferation rate was significantly lower than that in cells expressing microRNA let‑7 containing a mutated seed sequence. The addition of exogenous microRNA let‑7 resulted in an increased expression level of mature microRNA let‑7b, while the expression of CCND1 and CDK4 was reduced. Epidermal stem cells transfected with microRNA let‑7b were arrested in the G2/M phase and the percentage of cells in S‑phase was significantly reduced. In conclusion, let‑7b expression results in upregulation of the cell cycle-related proteins, CCND1 and CDK4, resulting in the excessive proliferation that leads to the formation of hypertrophic anal papillae.

Topics: Adult; Anal Canal; Cell Proliferation; Cyclin D1; Cyclin-Dependent Kinase 4; Epidermal Cells; Epidermis; Epithelial Cells; Female; Genetic Markers; HEK293 Cells; Hemorrhoids; Humans; Hypertrophy; Integrin alpha6; Integrin beta1; Male; MicroRNAs; Rectal Fistula; Stem Cells; Up-Regulation

Chronic renal failure (CRF) is associated with increased cardiovascular mortality, and medial vascular smooth muscle cell (VSMC) hypertrophy, proliferation, and calcification play a pivotal role in uremic vasculopathy. Glucose transporter-1 (GLUT1) facilitates the transport of glucose into VSMCs, and GLUT1 overexpression associated with high glucose influx leads to a stimulation of VSMC proliferation. However, the role of GLUT1 in uremic vasculopathy remains unclear. This study aimed to identify changes in the expression of GLUT1 in VSMCs in the setting of experimental uremia and investigate whether Akt/tuberous sclerosis complex subunit 2 (TSC2)/mammalian target of rapamycin (mTOR)/ribosomal S6 protein kinase (S6K) signaling, which plays a crucial role in VSMC proliferation and glucose metabolism, is involved in the regulation of GLUT1 expression.. In vivo experimental CRF was induced in Wistar rats by 5/6 nephrectomy, and the GLUT1 expression in aortic tissue was determined by the reverse transcriptase-polymerase chain reaction, immunoblotting, and immunohistochemical staining. Indoxyl sulfate (IS) is a uremic retention solute proven with pro-proliferative effect on rat VSMCs, and we further studied the expression of GLUT1 in rat A7r5 rat embryonic aortic cells stimulated by IS in the presence or absence of phloretin, a GLUT1 inhibitor, to explore the pathogenic role of GLUT1 in uremic vasculopathy. The contribution of Akt/TSC2/mTOR/S6K signaling in modifying the GLUT1 expression was also assessed.. Eight weeks after 5/6 nephrectomy, aortic tissue obtained from CRF rats exhibited increased wall thickness and VSMC hypertrophy, hyperplasia, and degeneration. Compared with the sham-operated control group, the messenger (m)RNA and protein abundance of GLUT1 were both markedly increased in CRF rats. In vitro, IS induced a significant increase in expression of GLUT1 protein as well as pro-proliferative cyclin D1 and p21 mRNA and a modest increase in expression of antiapoptotic p53 mRNA in A7r5 cells, whereas inhibition of GLUT1 mediated glucose influx reduced the pro-proliferative and antiapoptotic effects of IS. In addition to increased GLUT1 expression, IS significantly suppressed Akt and TSC2 phosphorylation after 6-hour and 12-hour treatment, but increased S6K phosphorylation after 3-hour treatment. Inactivation of mTOR downstream signaling by rapamycin treatment inhibited S6K phosphorylation and abolished the stimulatory effect of IS on GLUT1 expression.. In vivo and in vitro experimental CRF displayed prominent GLUT1 upregulation in VSMCs. The uremic toxin IS stimulated proliferation of VSMCs possibly through induction of GLUT1 expression. The Akt/TSC/mTOR/S6K signaling pathway may be one of the mechanisms underlying the upregulation of GLUT1 expression in uremic VSMCs.

Topics: Animals; Aorta; Apoptosis; Blotting, Western; Cell Line; Cell Proliferation; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p21; Disease Models, Animal; Glucose; Glucose Transporter Type 1; Hyperplasia; Hypertrophy; Immunohistochemistry; Indican; Male; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Nephrectomy; Phloretin; Phosphorylation; Proto-Oncogene Proteins c-akt; Rats; Rats, Wistar; Renal Insufficiency; Reverse Transcriptase Polymerase Chain Reaction; Ribosomal Protein S6 Kinases; RNA, Messenger; Signal Transduction; Sirolimus; Time Factors; TOR Serine-Threonine Kinases; Tuberous Sclerosis Complex 2 Protein; Tumor Suppressor Protein p53; Tumor Suppressor Proteins; Up-Regulation; Uremia

Hypertrophy of human mesangial cells (HMC) is among the earliest characteristics in patients with diabetic nephropathy (DN). Recently, we observed the upregulation of parathyroid hormone (PTH)-related protein (PTHrP) in experimental DN, associated with renal hypertrophy. Herein, we first examined whether PTHrP was overexpressed in human DN, and next assessed the putative role of this protein on high glucose (HG)-induced HMC hypertrophy. As previously found in mice, kidneys from diabetic patients showed an increased tubular and glomerular immunostaining for PTHrP. In HMC, HG medium increased PTHrP protein expression associated with the development of hypertrophy as assessed by cell protein content. This effect was also induced by PTHrP(1-36). HG and PTHrP(1-36)-induced hypertrophy were associated with an increase in cyclin D1 and p27Kip1 protein expression, a decreased cyclin E expression, and the prevention of cyclin E/cdk2 complex activation. Both PTHrP neutralizing antiserum (α-PTHrP) and the PTH/PTHrP receptor antagonist (JB4250) were able to abolish HG induction of hypertrophy, the aforementioned changes in cell cycle proteins, and also TGF-β1 up-regulation. Moreover, the capability of both HG and PTHrP(1-36) to induce HMC hypertrophy was abolished by α-TGFβ1. These data show for the first time that PTHrP is upregulated in the kidney of patients with DN. Our findings also demonstrate that PTHrP acts as an important mediator of HG-induced HMC hypertrophy by modulating cell cycle regulatory proteins and TGF-β1.

Topics: Animals; Cell Proliferation; Cells, Cultured; Cyclin D1; Cyclin E; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase Inhibitor p27; Diabetic Nephropathies; Female; Humans; Hypertrophy; Kidney; Male; Mesangial Cells; Mice; Middle Aged; Parathyroid Hormone-Related Protein; Transforming Growth Factor beta1

Myriocin (ISP-1) is a new type of immune inhibitor extracted from cordyceps sinensis. This study was to observe the effects of ISP-1 on the expression of cell cycle regulatory protein D1 (cyclinD1) in high glucose-induced hypertrophy rat glomerular mesangial cells (GMCs).. Rat GMCs were cultured in vitro and divided into three groups: high glucose (450 mg/dL D-glucose), normal glucose (100 mg/dL D-glucose, control) and ISP-1 (450 mg/dL D-glucose plus 100 μg/mL ISP-1). The protein expression of cyclinD1 was detected by flow cytometry.. The expression of cyclinD1 in GMCs in the high glucose group increased significantly in a time-dependent manner compared with that in the control group. ISP-1 treatment significantly inhibited the up-regulated expression of cyclinD1 induced by high concentration glucose, and the expression of cyclinD1 was restored to the level of the control group 48 and 72 hrs after ISP-1 treatment.. High concentration of glucose can up-regulate the expression of cyclinD1 in GMCs. ISP-1 may inhibit the up-regulated expression of cyclinD1, which might contribute to the protective effect of ISP-1 against GMC hypertrophy induced by high glucose.

Topics: Animals; Cyclin D1; Fatty Acids, Monounsaturated; G1 Phase; Glucose; Hypertrophy; Mesangial Cells; Rats; Rats, Sprague-Dawley

Cyclin D1, the retinoblastoma (Rb) protein, and the E2F transcription factors are involved in the pathogenesis of cardiac hypertrophy. Cyclin D1/cdk4 complexes, by phosphorylation, inactivate Rb, thereby abrogating its growth-inhibitory effect. Ventricular unloading is associated with reversible regulation of numerous cardiomyocyte molecular systems and decreased hypertrophy. Accordingly, the hypothesis whether the Rb/E2F-1 pathway is altered by ventricular unloading was tested, and correlations with the cyclin D1 protein expression and cardiomyocyte diameters were explored.. In 21 paired myocardial samples (before and after unloading) from patients with congestive heart failure (CHF), cyclin D1, phosphorylated Rb (pRb), its homologues p107 and p130 (pocket proteins), and E2F-1 were immunohistochemically investigated and morphometrically quantified. Cardiomyocyte diameters were morphometrically determined.. Cyclin D1 and the proteins of the Rb/E2F-1 pathway were significantly increased during CHF compared with controls and were significantly decreased after unloading. Cyclin D1, pRb, and p130 protein expression correlated significantly with cardiomyocyte diameters. A significant positive correlation was noted between the pocket proteins, E2F-1, and cyclin D1.. Increased protein expression of phosphorylated (inactivated) Rb and the pocket proteins is associated with cardiomyocyte hypertrophy in CHF. Rb inactivation might be explained by phosphorylation by increased numbers of cyclin D1/cdk4 complexes associated with cardiomyocyte hypertrophy. However, ventricular unloading can reversibly regulate this process. These data underscore the importance of cell cycle regulatory proteins in the pathogenesis of CHF-associated (maladaptive) cardiomyocyte hypertrophy and might offer novel clues for pharmacologic approaches of congestive heart failure.

Topics: Adolescent; Adult; Child; Child, Preschool; Crk-Associated Substrate Protein; Cyclin D1; E2F1 Transcription Factor; Female; Heart Failure; Heart Transplantation; Heart-Assist Devices; Humans; Hypertrophy; Male; Middle Aged; Myocytes, Cardiac; Retinoblastoma Protein; Retinoblastoma-Like Protein p107; Retrospective Studies; Signal Transduction; Ventricular Remodeling; Young Adult

Histone deacetylase (HDAC)7 is expressed in the early stages of embryonic development and may play a role in endothelial function.. This study aimed to investigate the role of HDAC7 in endothelial cell (EC) proliferation and growth and the underlying mechanism.. Overexpression of HDAC7 by adenoviral gene transfer suppressed human umbilical vein endothelial cell (HUVEC) proliferation by preventing nuclear translocation of beta-catenin and downregulation of T-cell factor-1/Id2 (inhibitor of DNA binding 2) and cyclin D1, leading to G(1) phase elongation. Further assays with the TOPFLASH reporter and quantitative RT-PCR for other beta-catenin target genes such as Axin2 confirmed that overexpression of HDAC7 decreased beta-catenin activity. Knockdown of HDAC7 by lentiviral short hairpin RNA transfer induced beta-catenin nuclear translocation but downregulated cyclin D1, cyclin E1 and E2F2, causing HUVEC hypertrophy. Immunoprecipitation assay and mass spectrometry analysis revealed that HDAC7 directly binds to beta-catenin and forms a complex with 14-3-3 epsilon, zeta, and eta proteins. Vascular endothelial growth factor treatment induced HDAC7 degradation via PLCgamma-IP3K (phospholipase Cgamma-inositol-1,4,5-trisphosphate kinase) signal pathway and partially rescued HDAC7-mediated suppression of proliferation. Moreover, vascular endothelial growth factor stimulation suppressed the binding of HDAC7 with beta-catenin, disrupting the complex and releasing beta-catenin to translocate into the nucleus.. These findings demonstrate that HDAC7 interacts with beta-catenin keeping ECs in a low proliferation stage and provides a novel insight into the mechanism of HDAC7-mediated signal pathways leading to endothelial growth.

Topics: 14-3-3 Proteins; Active Transport, Cell Nucleus; Adenoviridae; beta Catenin; Cell Cycle; Cell Proliferation; Cells, Cultured; Cyclin D1; Cyclin E; E2F2 Transcription Factor; Endothelial Cells; Genetic Vectors; Histone Deacetylases; Humans; Hypertrophy; Immunoprecipitation; Inhibitor of Differentiation Protein 2; Mass Spectrometry; Neovascularization, Physiologic; Oncogene Proteins; Phospholipase C gamma; Phosphotransferases (Alcohol Group Acceptor); Protein Binding; Protein Processing, Post-Translational; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Signal Transduction; Time Factors; Transduction, Genetic; Vascular Endothelial Growth Factor A

Skeletal muscles adapt to increasing workload by augmenting their fiber size, through mechanisms that are poorly understood. This study identifies the cytokine interleukin-6 (IL-6) as an essential regulator of satellite cell (muscle stem cell)-mediated hypertrophic muscle growth. IL-6 is locally and transiently produced by growing myofibers and associated satellite cells, and genetic loss of IL-6 blunted muscle hypertrophy in vivo. IL-6 deficiency abrogated satellite cell proliferation and myonuclear accretion in the preexisting myofiber by impairing STAT3 activation and expression of its target gene cyclin D1. The growth defect was indeed muscle cell intrinsic, since IL-6 loss also affected satellite cell behavior in vitro, in a STAT3-dependent manner. Myotube-produced IL-6 further stimulated cell proliferation in a paracrine fashion. These findings unveil a role for IL-6 in hypertrophic muscle growth and provide mechanistic evidence for the contribution of satellite cells to this process.

Topics: Animals; Blotting, Western; Cell Line; Cell Movement; Cell Proliferation; Cyclin D1; Enzyme-Linked Immunosorbent Assay; Hypertrophy; Immunohistochemistry; Interleukin-6; Mice; Mice, Knockout; Muscle Fibers, Skeletal; Muscle, Skeletal; Muscular Diseases; Myoblasts; Reverse Transcriptase Polymerase Chain Reaction; Satellite Cells, Skeletal Muscle; STAT3 Transcription Factor

We have previously shown that fenofibrate, a peroxisome proliferator-activated receptor-alpha activator, increases renal cytochrome P450 (CYP)-derived eicosanoids and improves endothelial function in pre-diabetic obese rats. The present study was designed to explore the efficacy of fenofibrate on blood pressure and renal injury in the advanced stage of type-2 diabetes. 26-week-old male Zucker diabetic fatty rats (ZDF) were fed fenofibrate (100 mg/kg/day) for 6 weeks. Chronic treatment with fenofibrate normalized systolic blood pressure and reduced glomerular size by 19% in diabetic rats. Western blot and fluorescent immunostaining revealed that the over-expression of collagen type IV and alpha-smooth muscle actin was significantly attenuated in the kidney of fenofibrate-treated ZDF (F-ZDF) rats. In addition, fenofibrate administration dramatically decreased the cyclin D1 protein level in the kidney of diabetic rats. In contrast, renal CYP2C23 and CYP4A proteins were significantly increased in F-ZDF rats. These fenofibrate effects were observed in the absence of significant changes in glucose, insulin or lipid levels. Taken together, our results demonstrate that fenofibrate may lower blood pressure and attenuate glomerular hypertrophy and collagen accumulation through the downregulation of cyclin D1 and upregulation of CYP monooxygenases in the late stage of type-2 diabetes.

Topics: Actins; Animals; Blood Pressure; Blotting, Western; Collagen Type IV; Cyclin D1; Cytochrome P-450 CYP2J2; Cytochrome P-450 CYP4A; Cytochrome P-450 Enzyme System; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Enzyme Induction; Fenofibrate; Hypertrophy; Hypolipidemic Agents; Immunohistochemistry; Kidney; Kidney Glomerulus; Male; PPAR alpha; Rats; Rats, Zucker

Insulin-like growth factor (IGF)-1 is accumulated in the diabetic kidney and is considered to be involved in the development of glomerular sclerosis. Here, we investigate IGF-1 regulation of laminin, an extracellular matrix (ECM) component, and cyclin D1 and p21Cip1, cell-cycle progression factor, expressions in glomerular mesangial cells. We show that IGF-1 increases the level of laminin gamma1 and beta1 subunits approximately 1.5- and 2.5-fold, respectively, in a time-dependent manner. IGF-1 also stimulates protein kinase Akt/PKB phosphorylation at Thr 308, which correlates with its activity, up to 24 h. The Akt activation is coupled with Ser 9 phosphorylation of its downstream target, glycogen synthase kinase-3beta (GSK-3beta), which inhibits its kinase activity. Laminin beta1 is reduced significantly (P < 0.03) by inhibitors of Akt and p38MAPK whereas laminin gamma1 is not affected. Surprisingly, IGF-1 activates the expression of both cyclin D1 and cell-cycle arrest factor, p21Cip1 parallely. Pharmacological inhibition of calcineurin by cyclosporin A blocks IGF-1-induced cyclin D1 and p21Cip1expression significantly (P < 0.05). IGF-1 enhances cellular metabolic activity and viability of rat mesangial cells; however, they are arrested at the G1 phase of cell cycle as revealed by the FACS analysis. These results indicate that IGF-1 mediates mesangial cell-cycle progression, hypertrophy, and ECM protein synthesis. The Akt/GSK-3beta, p38MAPK, and calcineurin pathways may play an important role in IGF-1 signaling, cell-cycle regulation, and matrix gene expression in mesangial cells leading to the development of diabetic glomerulopathy.

Topics: Animals; Cell Cycle; Cell Line; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p21; Extracellular Matrix Proteins; Gene Expression Regulation; Glomerular Mesangium; Hypertrophy; Insulin-Like Growth Factor I; Intracellular Signaling Peptides and Proteins; Laminin; Rats; Signal Transduction

The purpose of this study was to identify the potential downstream functions associated with mammalian target of rapamycin (mTOR) signaling during myotube hypertrophy. Terminally differentiated myotubes were serum stimulated for 3, 6, 12, 24, and 48 h. This treatment resulted in significant myotube hypertrophy (protein/DNA) and increased RNA content (RNA/DNA) with no changes in DNA content or indices of cell proliferation. During myotube hypertrophy, the increase in RNA content was accompanied by an increase in tumor suppressor protein retinoblastoma (Rb) phosphorylation and a corresponding increase in the availability of the ribosomal DNA transcription factor upstream binding factor (UBF). Serum stimulation also induced an increase in cyclin D1 protein expression in the differentiated myotubes with a concomitant increase in cyclin D1-dependent cyclin-dependent kinase (CDK)-4 activity toward Rb. The increases in myotube hypertrophy and RNA content were blocked by rapamycin treatment, which also prevented the increase in cyclin D1 protein expression, CDK-4 activity, Rb phosphorylation, and the increase in UBF availability. Our findings demonstrate that activation of mTOR is necessary for myotube hypertrophy and suggest that the role of mTOR is in part to modulate cyclin D1-dependent CDK-4 activity in the regulation of Rb and ribosomal RNA synthesis. On the basis of these results, we propose that common molecular mechanisms contribute to the regulation of myotube hypertrophy and growth during the G1 phase of the cell cycle.

Topics: Animals; Cell Cycle; Cell Enlargement; Cells, Cultured; Culture Media; Cyclin D1; Cyclin-Dependent Kinase 4; Hypertrophy; Muscle Fibers, Skeletal; Muscle, Skeletal; Myoblasts; Phosphorylation; Pol1 Transcription Initiation Complex Proteins; Protein Kinases; Rats; Retinoblastoma Protein; RNA, Ribosomal; Serum; Sirolimus; TOR Serine-Threonine Kinases

Insulin-like growth factor-I (IGF-I) has been shown to stimulate a hypertrophy response in skeletal muscles in vivo. In vitro studies have delineated two primary intracellular pathways that appear to mediate the effects of IGF-I in skeletal muscle: the Ras-ERK pathway and the phosphoinositide-3 kinase pathway. In vitro, the Ras pathway appears to regulate the mitogenic effects of IGF-I signaling, whereas the phosphoinositide-3 kinase pathway is associated with cellular differentiation. On the basis of the results from in vitro studies, we hypothesized that the coinfusion of both IGF-I and an inhibitor of the Ras pathway would result in some increase in muscle protein but an inhibition of cell proliferation. Our results show that 14 days of coinfusion of MAPK/ERK kinase inhibitor PD-098059 (PD) limited the phosphorylation of ERK and prevented IGF-I induced increases in protein (18%, P < 0.05 vs. 7%, not significant) or myofibrillar protein (23%, P < 0.01 vs. 5%, not significant). However, there were similar increases in indicators of cell proliferation (e.g., total DNA, 50 and 52%, P < 0.001) in both the IGF- and IGF+PD-infused muscles. The most notable impact on IGF-I signaling was a significant blunting of IGF-I induced increase in S6K1 phosphorylation by PD-98059 coinfusion ( approximately 5-fold, P < 0.001 vs. 3-fold, P < 0.01). These results suggest that there are interactions between the various pathways down stream of the IGF-I receptor that may behave differently in vivo than in myogenic cell lines in vitro.

Topics: Adaptation, Physiological; Animals; Cell Division; Cyclin D1; Enzyme Inhibitors; Female; Flavonoids; Hypertrophy; Insulin-Like Growth Factor Binding Protein 4; Insulin-Like Growth Factor Binding Protein 5; Insulin-Like Growth Factor I; MAP Kinase Signaling System; Muscle Fibers, Skeletal; Muscle, Skeletal; Rats; Rats, Sprague-Dawley; RNA, Messenger

Irradiation of rat skeletal muscles before increased loading has been shown to prevent compensatory hypertrophy for periods of up to 4 wk, possibly by preventing satellite cells from proliferating and providing new myonuclei. Recent work suggested that stem cell populations exist that might allow irradiated muscles to eventually hypertrophy over time. We report that irradiation essentially prevented hypertrophy in rat muscles subjected to 3 mo of functional overload (OL-Ir). The time course and magnitude of changes in cellular and molecular markers of anabolic and myogenic responses were similar in the OL-Ir and the contralateral nonirradiated, overloaded (OL) muscles for the first 3-7 days. These markers then returned to control levels in OL-Ir muscles while remaining elevated in OL muscles. The number of myonuclei and amount of DNA were increased markedly in OL but not OL-Ir muscles. Thus it appears that stem cells were not added to the irradiated muscles in this time period. These data are consistent with the theory that the addition of new myonuclei may be required for compensatory hypertrophy in the rat.

Topics: Adaptation, Physiological; Animals; Biomarkers; Body Weight; Cell Division; Cell Nucleus; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; DNA; Female; Hindlimb; Hypertrophy; Muscle Contraction; Muscle, Skeletal; Myogenin; Myosin Heavy Chains; Phosphorylation; Protein Isoforms; Rats; Rats, Sprague-Dawley; RNA, Messenger; Stem Cells; Stress, Mechanical; Time

To determine the role of cell-cycle proteins in regulating pathological renal hypertrophy, diabetes was induced in mice expressing a human retinoblastoma (RB) transgene and in wild-type littermates. Whole-kidney and glomerular hypertrophy caused by hyperglycemia was associated with specific G1 phase cell-cycle events: early and sustained increase in expression of cyclin D1 and activation of cyclin D1-cdk4 complexes, but no change in expression of cyclin E or cdk2 activity. Overexpression of RB alone likewise caused hypertrophy and increased only cyclin D1-cdk4 activity; these effects were not further augmented by high glucose. Identical observations were made when isolated mesangial cells conditionally overexpressing RB from a tetracycline-repressible system hypertrophied in response to high glucose. A mitogenic signal in the same cell-culture system, in contrast, transiently and sequentially activated both cyclin D1-cdk4 and cyclin E-cdk2. In vivo and in cultured mesangial cells, high glucose resulted in persistent partial phosphorylation of RB, an event catalyzed specifically by cyclin D1-cdk4. These data indicate that mesangial hypertrophy caused by hyperglycemia in diabetes results in sustained cyclin D1-cdk4-dependent phosphorylation of RB and maintenance of mesangial cells in the early-to-middle G1 phase of the cell cycle.

Topics: Animals; Cells, Cultured; Cyclin D1; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinases; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Disease Models, Animal; Glomerular Mesangium; Humans; Hypertrophy; Mice; Mice, Transgenic; Phosphorylation; Proto-Oncogene Proteins; Retinoblastoma Protein