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Bai Y, Zhang Q, Zhou Q, Zhang Y, Nong H, Liu M, Shi Z, Zeng G, Zong S. Effects of inhibiting PDK‑1 expression in bone marrow mesenchymal stem cells on osteoblast differentiation in vitro. Mol Med Rep 2020; 23:118. [PMID: 33300048 PMCID: PMC7751487 DOI: 10.3892/mmr.2020.11757] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 11/02/2020] [Indexed: 01/22/2023] Open
Abstract
Osteoblasts are the main functional cells in bone formation, which are responsible for the synthesis, secretion and mineralization of bone matrix. The PI3K/AKT signaling pathway is strongly associated with the differentiation and survival of osteoblasts. The 3-phosphoinositide-dependent protein kinase-1 (PDK-1) protein is considered the master upstream lipid kinase of the PI3K/AKT cascade. The present study aimed to investigate the role of PDK-1 in the process of mouse osteoblast differentiation in vitro. In the BX-912 group, BX-912, a specific inhibitor of PDK-1, was added to osteoblast induction medium (OBM) to treat bone marrow mesenchymal stem cells (BMSCs), whereas the control group was treated with OBM alone. Homozygote PDK1flox/flox mice were designed and generated, and were used to obtain BMSCsPDK1flox/flox. Subsequently, an adenovirus containing Cre recombinase enzyme (pHBAd-cre-EGFP) was used to disrupt the PDK-1 gene in BMSCsPDK1flox/flox; this served as the pHBAd-cre-EGFP group and the efficiency of the disruption was verified. Western blot analysis demonstrated that the protein expression levels of phosphorylated (p)-PDK1 and p-AKT were gradually increased during the osteoblast differentiation process. Notably, BX-912 treatment and disruption of the PDK-1 gene with pHBAd-cre-EGFP effectively reduced the number of alkaline phosphatase (ALP)-positive cells and the optical density value of ALP activity, as well as the formation of cell mineralization. The mRNA expression levels of PDK-1 in the pHBAd-cre-EGFP group were significantly downregulated compared with those in the empty vector virus group on days 3–7. The mRNA expression levels of the osteoblast-related genes RUNX2, osteocalcin and collagen I were significantly decreased in the BX-912 and pHBAd-cre-EGFP groups on days 7 and 21 compared with those in the control and empty vector virus groups. Overall, the results indicated that BX-912 and disruption of the PDK-1 gene in vitro significantly inhibited the differentiation and maturation of osteoblasts. These experimental results provided an experimental and theoretical basis for the role of PDK-1 in osteoblasts.
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Affiliation(s)
- Yiguang Bai
- Department of Spine Osteopathia, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Qiong Zhang
- Department of Nutrition and Food Hygiene, College of Public Hygiene of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Quan Zhou
- Collaborative Innovation Center of Guangxi Biological Medicine, Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Yanan Zhang
- Collaborative Innovation Center of Guangxi Biological Medicine, Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Haibin Nong
- Department of Spine Osteopathia, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Mingfu Liu
- Department of Spine Osteopathia, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Zhuohua Shi
- Department of Spine Osteopathia, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Gaofeng Zeng
- Department of Nutrition and Food Hygiene, College of Public Hygiene of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Shaohui Zong
- Department of Spine Osteopathia, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
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Kan J, Velliquette RA, Grann K, Burns CR, Scholten J, Tian F, Zhang Q, Gui M. A novel botanical formula prevents diabetes by improving insulin resistance. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2017; 17:352. [PMID: 28679380 PMCID: PMC5499036 DOI: 10.1186/s12906-017-1848-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Accepted: 06/20/2017] [Indexed: 12/29/2022]
Abstract
Background Type 2 diabetes mellitus (T2DM) is a major risk factor for cardiovascular disease, and the prevalence has increased significantly in recent decades to epidemic proportions in China. Individually, fenugreek (Trigonella foenum graecum) seed, mulberry (Morus alba L.) leaf and American ginseng (Panax quinquefolius) root can improve glycemia in various animal models and humans with impaired glucose metabolism and T2DM. The aim of this study was to design an optimized botanical formula containing these herbal extracts as a nutritional strategy for the prevention of insulin resistance and T2DM. Methods Cell-free α-amylase and α-glucosidase enzyme assays were used to determine inhibitory potential of extracts. Glucose uptake was examined in differentiated human adipocytes using radiolabeled 2-deoxyglucose. Male Sprague Dawley rats were divided and glycemia balanced into 5 groups: two controls (naïve and model) and three doses of the botanical test formula containing standardized fenugreek seed, mulberry leaf and American ginseng extracts (42.33, 84.66 and 169.33 mg/kg BW). Insulin resistance and T2DM was induced by feeding animals a high fat diet and with an alloxan injection. Glucose tolerance was examined by measuring serum glucose levels following an oral glucose load. Results Fenugreek seed and mulberry leaf dose dependently inhibited α-amylase (IC50 = 73.2 μg/mL) and α-glucosidase (IC50 = 111.8 ng/mL), respectively. All three botanical extracts improved insulin sensitivity and glucose uptake in human adipocytes, which lead to the design of an optimized botanical test formula. In a rat model of insulin resistance and T2DM, the optimized botanical test formula improved fasting serum glucose levels, fasting insulin resistance and the development of impaired glucose tolerance. The reduction in epididymal adipose tissue GLUT4 and PDK1 expression induced by high fat diet and alloxan was blunted by the botanical test formula. Conclusions A novel botanical formula containing standardized extracts of mulberry leaf, fenugreek seed and American ginseng at a ratio of 1:1.3:3.4 prevented the development of insulin resistance, impaired glucose tolerance and T2DM. Given the rising need for effective non-drug targeting of insulin resistance and progression to T2DM, complementary and alternative nutritional strategies without intolerable side effects could have meaningful impact on metabolic health and diabetes risks.
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Ku SK, Sung SH, Choung JJ, Choi JS, Shin YK, Kim JW. Anti-obesity and anti-diabetic effects of a standardized potato extract in ob/ ob mice. Exp Ther Med 2016; 12:354-364. [PMID: 27347062 DOI: 10.3892/etm.2016.3256] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 03/15/2016] [Indexed: 12/16/2022] Open
Abstract
The potato (Solanum tuberosum) has been cultivated globally for food for millenia. Potato contains proteinase inhibitor II, which catalyzes the release of cholecystokinin (CCK), leading to delayed gastric emptying in humans. The present study investigated the anti-obesity effects of Slendesta™ Potato Extract (SLD), a standardized potato extract containing 5% proteinase inhibitor II, in the ob/ob obese mice. Three doses of SLD (50, 150 or 300 mg/kg) were orally administered to ob/ob mice once a day for 28 days, whereas control mice were administered distilled water. Four weeks after SLD treatment, the changes in body weight, food consumption, epididymal fat weight, serum chemistry, insulin, leptin and adiponectin contents, and fat histopathology were determined and compared with ob/ob mice treated with 750 mg/kg conjugate linoleic acid. As a result of SLD treatment in the obese mice, body weight, food consumption, epididymal fat, serum biochemistry, histomorphological changes of fat and pancreas were significantly and dose-dependently decreased compared with ob/ob control mice. These obesity and type 2 diabetes associated alterations were significantly inhibited after SLD treatment for 28 days. Thus, the present results indicate that SLD has potential as an alternative therapeutic agent for obesity.
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Affiliation(s)
- Sae Kwang Ku
- Department of Anatomy and Histology, College of Oriental Medicine, Daegu Haany University, Gyeongsan-Si, Gyeongsanbuk-Do 712-715, Republic of Korea
| | - Soo Hyun Sung
- Aribio, Inc., Byeoksan Digital Valley, Suite 1004, Yeongdeungpo-Gu, Seoul 150-095, Republic of Korea
| | | | - Jae-Suk Choi
- Division of Bioindustry, College of Medical and Life Sciences, Silla University, Sasang-Gu, Busan 617-736, Republic of Korea
| | - Yong Kook Shin
- Department of Natural Medicine Resources, Semyung University, Jecheon-Si, Chungcheongbuk-Do 390-711, Republic of Korea
| | - Joo Wan Kim
- Aribio, Inc., Byeoksan Digital Valley, Suite 1004, Yeongdeungpo-Gu, Seoul 150-095, Republic of Korea
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A high fat diet induces sex-specific differences in hepatic lipid metabolism and nitrite/nitrate in rats. Nitric Oxide 2016; 54:51-9. [DOI: 10.1016/j.niox.2016.02.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 02/17/2016] [Accepted: 02/23/2016] [Indexed: 02/08/2023]
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van Dam AD, Kooijman S, Schilperoort M, Rensen PCN, Boon MR. Regulation of brown fat by AMP-activated protein kinase. Trends Mol Med 2015; 21:571-9. [PMID: 26271143 DOI: 10.1016/j.molmed.2015.07.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 07/04/2015] [Accepted: 07/07/2015] [Indexed: 12/23/2022]
Abstract
Novel strategies are needed to reduce the obesity epidemic. One promising strategy is activation of brown adipose tissue (BAT), either via the brain or directly, which increases energy expenditure by combustion of fatty acids (FAs) into heat. The enzyme complex AMP-activated protein kinase (AMPK) is crucially involved in energy metabolism and is highly expressed in both brain and BAT, regulating thermogenesis. As a general rule, BAT activity and energy expenditure are increased either by suppression of AMPK activity in the brain, resulting in enhanced sympathetic outflow towards BAT, or by activation of AMPK in BAT. Targeting AMPK may thus hold therapeutic potential for the treatment of obesity and related disorders.
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Affiliation(s)
- Andrea D van Dam
- Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, post zone C7Q, PO Box 9600, 2300 RC Leiden, The Netherlands.
| | - Sander Kooijman
- Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, post zone C7Q, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Maaike Schilperoort
- Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, post zone C7Q, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Patrick C N Rensen
- Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, post zone C7Q, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Mariëtte R Boon
- Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, post zone C7Q, PO Box 9600, 2300 RC Leiden, The Netherlands
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Kang SJ, Lee JE, Lee EK, Jung DH, Song CH, Park SJ, Choi SH, Han CH, Ku SK, Lee YJ. Fermentation with Aquilariae Lignum enhances the anti-diabetic activity of green tea in type II diabetic db/db mouse. Nutrients 2014; 6:3536-71. [PMID: 25207824 PMCID: PMC4179175 DOI: 10.3390/nu6093536] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 08/05/2014] [Accepted: 08/11/2014] [Indexed: 11/16/2022] Open
Abstract
The major components of tea may be significantly influenced according to the type of fermentation, and consequently the effects of different teas will differ. We examined whether green tea fermented with Aquilariae Lignum (fGT) shows a stronger anti-diabetic effect than unfermented green tea (GT) on mice with type 2 diabetes. To evaluate the anti-obesity effect of fGT, we assessed body weight, fecal excretion, serum leptin levels, exocrine pancreatic zymogen granule contents, and periovarian fat weight and adiponectin contents. Blood glucose levels, pancreatic weight, and numbers of pancreatic islet insulin- and glucagon-producing cells were determined to evaluate anti-hypoglycemic effects, while total cholesterol, triglyceride, and low- and high-density lipoprotein levels were determined to evaluate anti-hyperlipidemic effects. The antioxidant effect of fGT was detected by measuring malondialdehyde and glutathione contents and the activities of catalase and superoxide dismutase. fGT showed anti-obesity, anti-hypoglycemic, anti-hyperlipidemia, and antioxidant effects. Additionally, fGT exerted stronger anti-diabetic effects compared with GT. Collectively, these results suggested that fGT fermented with the appropriate amounts of Aquilariae Lignum (49:1) has a stronger effect compared with GT. Thus, fGT is a promising and potent new therapeutic agent for type 2 diabetes.
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Affiliation(s)
- Su Jin Kang
- The Medical Research Center for Globalization of Herbal Medicine, Daegu Haany University, Gyeongsan 712-715, Korea.
| | - Ji Eun Lee
- The Medical Research Center for Globalization of Herbal Medicine, Daegu Haany University, Gyeongsan 712-715, Korea.
| | - Eun Kyung Lee
- The Medical Research Center for Globalization of Herbal Medicine, Daegu Haany University, Gyeongsan 712-715, Korea.
| | | | - Chang Hyun Song
- The Medical Research Center for Globalization of Herbal Medicine, Daegu Haany University, Gyeongsan 712-715, Korea.
| | - Soo Jin Park
- The Medical Research Center for Globalization of Herbal Medicine, Daegu Haany University, Gyeongsan 712-715, Korea.
| | - Seong Hun Choi
- Department of Histology and Anatomy, College of Korean Medicine, Daegu Haany University, Gyeongsan 712-715, Korea.
| | - Chang Hyun Han
- Department of Medical History & Literature Group, Korea Institute of Oriental Medicine, Daejeon 305-811, Korea.
| | - Sae Kwang Ku
- The Medical Research Center for Globalization of Herbal Medicine, Daegu Haany University, Gyeongsan 712-715, Korea.
| | - Young Joon Lee
- The Medical Research Center for Globalization of Herbal Medicine, Daegu Haany University, Gyeongsan 712-715, Korea.
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Nasu-Kawaharada R, Nakamura A, Kakarla SK, Blough ER, Kohama K, Kohama T. A maternal diet rich in fish oil may improve cardiac Akt-related signaling in the offspring of diabetic mother rats. Nutrition 2013; 29:688-92. [PMID: 23466053 DOI: 10.1016/j.nut.2012.11.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 10/22/2012] [Accepted: 11/24/2012] [Indexed: 10/27/2022]
Abstract
OBJECTIVE Newborns of diabetic mothers have abnormal circulatory organs, so in this study, we explore insulin signaling in the newborn rat heart. METHODS Pregnant rats were divided into streptozotocin-induced diabetic groups (DM) and control groups (CM). Rats were fed lard (21% fat), fish oil (21% fat), or a control diet (7% fat). To examine changes in insulin signaling in the hearts of infants of diabetic mothers (IDM) in relation to diet, we isolated the hearts from the IDM and control infants and determined the phosphorylation levels of Akt308, Akt473, p38, c-jun-NH2-terminal protein kinase (JNK), and extracellular signal-regulated protein kinase (ERK), and the expression levels of phosphoinositide-dependent protein kainase1 (PDK1) and mammalian target of rapamycin (mTOR). RESULTS The mean blood glucose levels in the DM group and their infants were significantly higher than those in the CM group (P < 0.05) and their infants (P < 0.05), but the mean blood glucose levels of all infants was normal on postnatal d 4. Phosphorylation levels of Akt (Thr 308) (P < 0.05) and Akt (Ser 473) and the expression levels of PDK1 and mTOR were lower in infants of diabetic mothers (IDM) than in control infants. The phosphorylation level of Akt (Ser 473) and the expression level of mTOR increased in IDM fed the fish oil diet compared with those fed the lard diet (P < 0.05). CONCLUSION A maternal diet rich in fish oil improves cardiac Akt-related signaling in the offspring of diabetic rats.
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Affiliation(s)
- Ritsuko Nasu-Kawaharada
- Department of Health and Nutrition, Takasaki University of Health and Welfare, Takasaki, Japan
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8
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Role of AMP-activated protein kinase in adipose tissue metabolism and inflammation. Clin Sci (Lond) 2013; 124:491-507. [PMID: 23298225 DOI: 10.1042/cs20120536] [Citation(s) in RCA: 225] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
AMPK (AMP-activated protein kinase) is a key regulator of cellular and whole-body energy balance. AMPK phosphorylates and regulates many proteins concerned with nutrient metabolism, largely acting to suppress anabolic ATP-consuming pathways while stimulating catabolic ATP-generating pathways. This has led to considerable interest in AMPK as a therapeutic target for the metabolic dysfunction observed in obesity and insulin resistance. The role of AMPK in skeletal muscle and the liver has been extensively studied, such that AMPK has been demonstrated to inhibit synthesis of fatty acids, cholesterol and isoprenoids, hepatic gluconeogenesis and translation while increasing fatty acid oxidation, muscle glucose transport, mitochondrial biogenesis and caloric intake. The role of AMPK in the other principal metabolic and insulin-sensitive tissue, adipose, remains poorly characterized in comparison, yet increasing evidence supports an important role for AMPK in adipose tissue function. Obesity is characterized by hypertrophy of adipocytes and the development of a chronic sub-clinical pro-inflammatory environment in adipose tissue, leading to increased infiltration of immune cells. This combination of dysfunctional hypertrophic adipocytes and a pro-inflammatory environment contributes to insulin resistance and the development of Type 2 diabetes. Exciting recent studies indicate that AMPK may not only influence metabolism in adipocytes, but also act to suppress this pro-inflammatory environment, such that targeting AMPK in adipose tissue may be desirable to normalize adipose dysfunction and inflammation. In the present review, we discuss the role of AMPK in adipose tissue, focussing on the regulation of carbohydrate and lipid metabolism, adipogenesis and pro-inflammatory pathways in physiological and pathophysiological conditions.
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PDK1 coordinates survival pathways and beta-adrenergic response in the heart. Proc Natl Acad Sci U S A 2009; 106:8689-94. [PMID: 19429709 DOI: 10.1073/pnas.0900064106] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The 3-phosphoinositide-dependent kinase-1 (PDK1) plays an important role in the regulation of cellular responses in multiple organs by mediating the phosphoinositide 3-kinase (PI3-K) signaling pathway through activating AGC kinases. Here we defined the role of PDK1 in controlling cardiac homeostasis. Cardiac expression of PDK1 was significantly decreased in murine models of heart failure. Tamoxifen-inducible and heart-specific disruption of Pdk1 in adult mice caused severe and lethal heart failure, which was associated with apoptotic death of cardiomyocytes and beta(1)-adrenergic receptor (AR) down-regulation. Overexpression of Bcl-2 protein prevented cardiomyocyte apoptosis and improved cardiac function. In addition, PDK1-deficient hearts showed enhanced activity of PI3-Kgamma, leading to robust beta(1)-AR internalization by forming complex with beta-AR kinase 1 (betaARK1). Interference of betaARK1/PI3-Kgamma complex formation by transgenic overexpression of phosphoinositide kinase domain normalized beta(1)-AR trafficking and improved cardiac function. Taken together, these results suggest that PDK1 plays a critical role in cardiac homeostasis in vivo by serving as a dual effector for cell survival and beta-adrenergic response.
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Bhonde MR, Gupte RD, Dadarkar SD, Jadhav MG, Tannu AA, Bhatt P, Bhatia DR, Desai NK, Deore V, Yewalkar N, Vishwakarma RA, Sharma S, Kumar S, Dagia NM. A novel mTOR inhibitor is efficacious in a murine model of colitis. Am J Physiol Gastrointest Liver Physiol 2008; 295:G1237-45. [PMID: 18927209 DOI: 10.1152/ajpgi.90537.2008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Ulcerative colitis is an autoimmune-inflammatory disease characterized by increased proliferation of colonic epithelial cells, dysregulation of signal transduction pathways, elevated mucosal T cell activation, increased production of proinflammatory cytokines, and enhanced leukocyte infiltration into colonic interstitium. Several compounds that possess antiproliferative properties and/or inhibit cytokine production exhibit a therapeutic effect in murine models of colitis. Mammalian target of rapamycin (mTOR), a protein kinase regulating cell proliferation, is implicated in colon carcinogenesis. In this study, we report that a novel haloacyl aminopyridine-based molecule (P2281) is a mTOR inhibitor and is efficacious in a murine model of human colitis. In vitro studies using Western blot analysis and cell-based ELISA assays showed that P2281 inhibits mTOR activity in colon cancer cells. In vitro and in vivo assays of proinflammatory cytokine production revealed that P2281 diminishes induced IFN-gamma production but not TNF-alpha production, indicating preferential inhibitory effects of P2281 on T cell function. In the dextran sulfate sodium (DSS) model of colitis, 1) macroscopic colon observations demonstrated that P2281 significantly inhibited DSS-induced weight loss, improved rectal bleeding index, decreased disease activity index, and reversed DSS-induced shortening of the colon; 2) histological analyses of colonic tissues revealed that P2281 distinctly attenuated DSS-induced edema, prominently diminished the leukocyte infiltration in the colonic mucosa, and resulted in protection against DSS-induced crypt damage; and 3) Western blot analysis showed that P2281 blocks DSS-induced activation of mTOR. Collectively, these results provide direct evidence that P2281, a novel mTOR inhibitor, suppresses DSS-induced colitis by inhibiting T cell function and is a potential therapeutic for colitis. Given that compounds with anticancer activity show promising anti-inflammatory efficacy, our findings reinforce the cross-therapeutic functionality of potential drugs.
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Affiliation(s)
- Mandar R Bhonde
- Dept. of Pharmacology, Piramal Life Sciences Limited, 1 Nirlon Complex, Off Western Express Highway, Goregaon (East Mumbai - 400063, Maharashtra, India. )
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Freeley M, Park J, Yang KJ, Wange RL, Volkov Y, Kelleher D, Long A. Loss of PTEN expression does not contribute to PDK-1 activity and PKC activation-loop phosphorylation in Jurkat leukaemic T cells. Cell Signal 2007; 19:2444-57. [PMID: 17826953 DOI: 10.1016/j.cellsig.2007.07.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Revised: 07/13/2007] [Accepted: 07/23/2007] [Indexed: 02/06/2023]
Abstract
Unopposed PI3-kinase activity and 3'-phosphoinositide production in Jurkat T cells, due to a mutation in the PTEN tumour suppressor protein, results in deregulation of PH domain-containing proteins including the serine/threonine kinase PKB/Akt. In Jurkat cells, PKB/Akt is constitutively active and phosphorylated at the activation-loop residue (Thr308). 3'-phosphoinositide-dependent protein kinase-1 (PDK-1), an enzyme that also contains a PH domain, is thought to catalyse Thr308 phosphorylation of PKB/Akt in addition to other kinase families such as PKC isoforms. It is unknown however if the loss of PTEN in Jurkat cells also results in unregulated PDK-1 activity and whether such loss impacts on activation-loop phosphorylation of other putative PDK-1 substrates such as PKC. In this study we have addressed if loss of PTEN in Jurkat T cells affects PDK-1 catalytic activity and intracellular localisation. We demonstrate that reducing the level of 3'-phosphoinositides in Jurkat cells with pharmacological inhibitors of PI3-kinase or expression of PTEN does not affect PDK-1 activity, Ser241 phosphorylation or intracellular localisation. In support of this finding, we show that the levels of PKC activation-loop phosphorylation are unaffected by reductions in the levels of 3'-phosphoinositides. Instead, the dephosphorylation that occurs on PKB/Akt at Thr308 following reductions in 3'-phosphoinositides is dependent on PP2A-like phosphatase activity. Our finding that PDK-1 functions independently of 3'-phosphoinositides in T cells is also confirmed by studies in HuT-78 T cells, a PTEN-expressing cell line with undetectable levels of 3'-phosphoinositides. We conclude therefore that loss of PTEN expression in Jurkat T cells does not impact on the PDK-1/PKC pathway and that only a subset of kinases, such as PKB/Akt, are perturbed as a consequence PTEN loss.
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Affiliation(s)
- Michael Freeley
- Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College, Dublin, Ireland.
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Seki T, Irie N, Nakamura K, Sakaue H, Ogawa W, Kasuga M, Yamamoto H, Ohmori S, Saito N, Sakai N. Fused protein of deltaPKC activation loop and PDK1-interacting fragment (deltaAL-PIF) functions as a pseudosubstrate and an inhibitory molecule for PDK1 when expressed in cells. Genes Cells 2006; 11:1051-70. [PMID: 16923125 DOI: 10.1111/j.1365-2443.2006.01003.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
To elucidate the role of 3-phosphoinositide-dependent protein kinase-1 (PDK1) in cellular signaling, we constructed and expressed a pseudosubstrate of PDK1, designated as deltaAL-PIF, and characterized its properties in cultured cells. deltaAL-PIF consists of two fused proteins of the protein kinase Cdelta (deltaPKC) activation loop (deltaAL) and PDK1-interacting fragment (PIF). The phosphorylation of deltaAL-PIF was detected with anti-deltaPKC phospho-Thr505-specific antibody and was increased in proportion to the expression level of co-expressed GST-PDK1, indicating that it acts as a pseudosubstrate of PDK1. In cells expressing deltaAL-PIF, basal phosphorylation level at the activation loop of PKBalpha, deltaPKC and gammaPKC was reduced, compared with that in control cells, suggesting that deltaAL-PIF functions as an inhibitory molecule for PDK1. deltaAL-PIF affected the stability, translocation and endogenous activity of PKCs. These effects of deltaAL-PIF on gammaPKC properties were confirmed by investigation using conditioned PDK1 knockout cells. Furthermore, apoptosis frequently occurred in cells expressing deltaAL-PIF for 3 days. These findings revealed that deltaAL-PIF served as an effective pseudosubstrate and an inhibitory molecule for PDK1, suggesting that this molecule can be used as a tool for investigating PDK-mediated cellular functions as well as being applicable for anti-cancer therapy.
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Affiliation(s)
- Takahiro Seki
- Department of Molecular and Pharmacological Neuroscience, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima 734-8551, Japan
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Fiory F, Alberobello AT, Miele C, Oriente F, Esposito I, Corbo V, Ruvo M, Tizzano B, Rasmussen TE, Gammeltoft S, Formisano P, Beguinot F. Tyrosine phosphorylation of phosphoinositide-dependent kinase 1 by the insulin receptor is necessary for insulin metabolic signaling. Mol Cell Biol 2006; 25:10803-14. [PMID: 16314505 PMCID: PMC1316974 DOI: 10.1128/mcb.25.24.10803-10814.2005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In L6 myoblasts, insulin receptors with deletion of the C-terminal 43 amino acids (IR(Delta43)) exhibited normal autophosphorylation and IRS-1/2 tyrosine phosphorylation. The L6 cells expressing IR(Delta43) (L6(IRDelta43)) also showed no insulin effect on glucose uptake and glycogen synthase, accompanied by a >80% decrease in insulin induction of 3-phosphoinositide-dependent protein kinase 1 (PDK-1) activity and tyrosine phosphorylation and of protein kinase B (PKB) phosphorylation at Thr(308). Insulin induced the phosphatidylinositol 3 kinase-dependent coprecipitation of PDK-1 with wild-type IR (IR(WT)), but not IR(Delta43). Based on overlay blotting, PDK-1 directly bound IR(WT), but not IR(Delta43). Insulin-activated IR(WT), and not IR(Delta43), phosphorylated PDK-1 at tyrosines 9, 373, and 376. The IR C-terminal 43-amino-acid peptide (C-terminal peptide) inhibited in vitro PDK-1 tyrosine phosphorylation by the IR. Tyr-->Phe substitution prevented this inhibitory action. In the L6(hIR) cells, the C-terminal peptide coprecipitated with PDK-1 in an insulin-stimulated fashion. This peptide simultaneously impaired the insulin effect on PDK-1 coprecipitation with IR(WT), on PDK-1 tyrosine phosphorylation, on PKB phosphorylation at Thr(308), and on glucose uptake. Upon insulin exposure, PDK-1 membrane persistence was significantly reduced in L6(IRDelta43) compared to control cells. In L6 cells expressing IR(WT), the C-terminal peptide also impaired insulin-dependent PDK-1 membrane persistence. Thus, PDK-1 directly binds to the insulin receptor, followed by PDK-1 activation and insulin metabolic effects.
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Affiliation(s)
- Francesca Fiory
- Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università di Napoli Federico II, Italy
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14
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Mora A, Lipina C, Tronche F, Sutherland C, Alessi D. Deficiency of PDK1 in liver results in glucose intolerance, impairment of insulin-regulated gene expression and liver failure. Biochem J 2005; 385:639-48. [PMID: 15554902 PMCID: PMC1134738 DOI: 10.1042/bj20041782] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The liver plays an important role in insulin-regulated glucose homoeostasis. To study the function of the PDK1 (3-phosphoinositide-dependent protein kinase-1) signalling pathway in mediating insulin's actions in the liver, we employed CRE recombinase/loxP technology to generate L(liver)-PDK1-/- mice, which lack expression of PDK1 in hepatocytes and in which insulin failed to induce activation of PKB in liver. The L-PDK1-/- mice were not insulin-intolerant, possessed normal levels of blood glucose and insulin under normal feeding conditions, but were markedly glucose-intolerant when injected with glucose. The L-PDK1-/- mice also possessed 10-fold lower levels of hepatic glycogen compared with control littermates, and were unable to normalize their blood glucose levels within 2 h after injection of insulin. The glucose intolerance of the L-PDK1-/- mice may be due to an inability of glucose to suppress hepatic glucose output through the gluconeogenic pathway, since the mRNA encoding hepatic PEPCK (phosphoenolpyruvate carboxykinase), G6Pase (glucose-6-phosphatase) and SREBP1 (sterol-regulatory-element-binding protein 1), which regulate gluconeogenesis, are no longer controlled by feeding. Furthermore, three other insulin-controlled genes, namely IGFBP1 (insulin-like-growth-factor-binding protein-1), IRS2 (insulin receptor substrate 2) and glucokinase, were regulated abnormally by feeding in the liver of PDK1-deficient mice. Finally, the L-PDK1-/- mice died between 4-16 weeks of age due to liver failure. These results establish that the PDK1 signalling pathway plays an important role in regulating glucose homoeostasis and controlling expression of insulin-regulated genes. They suggest that a deficiency of the PDK1 pathway in the liver could contribute to development of diabetes, as well as to liver failure.
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Affiliation(s)
- Alfonso Mora
- *MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
- To whom correspondence should be addressed: correspondence regarding PDK1 to Alfonso Mora (email ), and correspondence regarding gene expression to Calum Sutherland (email )
| | - Christopher Lipina
- †Neurosciences Institute, Division of Pathology and Neuroscience, Ninewells Hospital and Medical School, Dundee DD1 9SY, Scotland, U.K
| | - François Tronche
- ‡Centre National de la Recherche Scientifique FRE 2401, Collège de France, Paris, France
| | - Calum Sutherland
- †Neurosciences Institute, Division of Pathology and Neuroscience, Ninewells Hospital and Medical School, Dundee DD1 9SY, Scotland, U.K
- To whom correspondence should be addressed: correspondence regarding PDK1 to Alfonso Mora (email ), and correspondence regarding gene expression to Calum Sutherland (email )
| | - Dario R. Alessi
- *MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
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Hida K, Wada J, Eguchi J, Zhang H, Baba M, Seida A, Hashimoto I, Okada T, Yasuhara A, Nakatsuka A, Shikata K, Hourai S, Futami J, Watanabe E, Matsuki Y, Hiramatsu R, Akagi S, Makino H, Kanwar YS. Visceral adipose tissue-derived serine protease inhibitor: a unique insulin-sensitizing adipocytokine in obesity. Proc Natl Acad Sci U S A 2005; 102:10610-5. [PMID: 16030142 PMCID: PMC1180799 DOI: 10.1073/pnas.0504703102] [Citation(s) in RCA: 473] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2004] [Indexed: 01/08/2023] Open
Abstract
There is a rapid global rise in obesity, and the link between obesity and diabetes remains somewhat obscure. We identified an adipocytokine, designated as visceral adipose tissue-derived serpin (vaspin), which is a member of serine protease inhibitor family. Vaspin cDNA was isolated by from visceral white adipose tissues (WATs) of Otsuka Long-Evans Tokushima fatty (OLETF) rat, an animal model of abdominal obesity with type 2 diabetes. Rat, mouse, and human vaspins are made up of 392, 394, and 395 amino acids, respectively; exhibit approximately 40% homology with alpha1-antitrypsin; and are related to serine protease inhibitor family. Vaspin was barely detectable in rats at 6 wk and was highly expressed in adipocytes of visceral WATs at 30 wk, the age when obesity, body weight, and insulin levels peak in OLETF rats. The tissue expression of vaspin and its serum levels decrease with worsening of diabetes and body weight loss at 50 wk. The expression and serum levels were normalized with the treatment of insulin or insulin-sensitizing agent, pioglitazone, in OLETF rats. Administration of vaspin to obese CRL:CD-1 (ICR) (ICR) mice fed with high-fat high-sucrose chow improved glucose tolerance and insulin sensitivity reflected by normalized serum glucose levels. It also led to the reversal of altered expression of genes relevant to insulin resistance, e.g., leptin, resistin, TNFalpha, glucose transporter-4, and adiponectin. In DNA chip analyses, vaspin treatment resulted in the reversal of expression in approximately 50% of the high-fat high-sucrose-induced genes in WATs. These findings indicate that vaspin exerts an insulin-sensitizing effect targeted toward WATs in states of obesity.
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Affiliation(s)
- Kazuyuki Hida
- Department of Medicine and Clinical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama 700-8558, Japan
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16
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Mora A, Sakamoto K, McManus EJ, Alessi DR. Role of the PDK1-PKB-GSK3 pathway in regulating glycogen synthase and glucose uptake in the heart. FEBS Lett 2005; 579:3632-8. [PMID: 15961082 DOI: 10.1016/j.febslet.2005.05.040] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Revised: 05/26/2005] [Accepted: 05/27/2005] [Indexed: 12/22/2022]
Abstract
In order to investigate the importance of the PDK1-PKB-GSK3 signalling network in regulating glycogen synthase (GS) in the heart, we have employed tissue specific conditional knockout mice lacking PDK1 in muscle (mPDK1-/-), as well as knockin mice in which the protein kinase B (PKB) phosphorylation site on glycogen synthase kinase-3alpha (GSK3alpha) (Ser21) and GSK3beta (Ser9) is changed to Ala. We demonstrate that in hearts from mPDK1-/- or double GSK3alpha/GSK3beta knockin mice, insulin failed to stimulate the activity of GS or induce its dephosphorylation at residues that are phosphorylated by GSK3. We also establish that in the heart, both GSK3 isoforms participate in the regulation of GS, with GSK3beta playing a more prominent role. This contrasts with skeletal muscle where GSK3beta is the major regulator of insulin-induced GS activity. Despite the inability of insulin to stimulate glycogen synthesis in hearts from the mPDK1-/- or double GSK3alpha/GSK3beta knockin mice, these animals possessed normal levels of cardiac glycogen, demonstrating that total glycogen levels are regulated independently of insulin's ability to stimulate GS in the heart and that mechanisms such as allosteric activation of GS by glucose-6-phosphate and/or activation of GS by muscle contraction, could operate to maintain normal glycogen levels in these mice. We also demonstrate that in cardiomyocytes derived from the mPDK1-/- hearts, although the levels of glucose transporter type 4 (GLUT4) are increased 2-fold, insulin failed to stimulate glucose uptake, providing genetic evidence that PDK1 plays a crucial role in enabling insulin to promote glucose uptake in cardiac muscle.
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Affiliation(s)
- Alfonso Mora
- MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland
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17
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Mora A, Komander D, van Aalten DMF, Alessi DR. PDK1, the master regulator of AGC kinase signal transduction. Semin Cell Dev Biol 2004; 15:161-70. [PMID: 15209375 DOI: 10.1016/j.semcdb.2003.12.022] [Citation(s) in RCA: 614] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The interaction of insulin and growth factors with their receptors on the outside surface of a cell, leads to the activation of phosphatidylinositol 3-kinase (PI 3-kinase) and generation of the phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) second messenger at the inner surface of the cell membrane. One of the most studied signalling events controlled by PtdIns(3,4,5)P3, comprises the activation of a group of AGC family protein kinases, including isoforms of protein kinase B (PKB)/Akt, p70 ribosomal S6 kinase (S6K), serum- and glucocorticoid-induced protein kinase (SGK) and protein kinase C (PKC), which play crucial roles in regulating physiological processes relevant to metabolism, growth, proliferation and survival. Here, we review recent biochemical, genetic and structural studies on the 3-phosphoinositide-dependent protein kinase-1 (PDK1), which phosphorylates and activates the AGC kinase members regulated by PI 3-kinase. We also discuss whether inhibitors of PDK1 might have chemotherapeutic potential in the treatment of cancers in which the PDK1-regulated AGC kinases are constitutively activated.
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Affiliation(s)
- Alfonso Mora
- MRC Protein Phosphorylation Unit, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, UK
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