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Kim HJ, Im DU, Chau GC, Mishra NK, Kim IS, Um SH. Novel anti-adipogenic effect of CF 3-allylated indole in 3T3-L1 cells. Chem Biol Interact 2021; 352:109782. [PMID: 34932954 DOI: 10.1016/j.cbi.2021.109782] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 12/14/2021] [Accepted: 12/16/2021] [Indexed: 01/03/2023]
Abstract
Indole derivatives from various plants are known to have health benefits because of their anti-cancer, anti-oxidant, anti-inflammatory, and anti-tubercular effects. However, their effects on adipogenesis have not been fully elucidated yet. Herein, we show that a newly synthesized indole derivative, CF3-allylated indole, [(E)-1-(pyrimidin- 2-yl)-2-(4,4,4- trifluorobut-2-enyl)-1H-indole], effectively inhibits adipogenesis. We found that CF3-allylated indole inhibited lipid accumulation and suppressed the expression of CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator activated receptor γ (PPARγ) in 3T3-L1 cells. The inhibitory effect of CF3-allylated indole primarily occurred at the early phase of adipocyte differentiation by increasing intracellular cyclic adenosine monophosphate (cAMP) levels and enhancing protein kinase A (PKA) and adenosine monophosphate-activated protein kinase (AMPK) signaling. Conversely, depletion of PKA or treatment with a protein kinase A inhibitor (H89) reversed such inhibitory effects of CF3-allylated indole on adipogenesis and PPARγ expression. These results suggest that CF3-allylated indole inhibits early stages of adipogenesis by increasing phosphorylation of PKA/AMPK, leading to decreased expression of adipogenic genes in 3T3-L1 cells. These results indicate that CF3-allylated indole has potential for controlling initial adipocyte differentiation in metabolic disorders such as obesity.
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Affiliation(s)
- Hee Jung Kim
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, School of Medicine, Sungkyunkwan University, Suwon, Gyeonggi-do, 16419, Republic of Korea; Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Samsung Medical Center, Sungkyunkwan University, Seoul, 06351, Republic of Korea
| | - Dong Uk Im
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, School of Medicine, Sungkyunkwan University, Suwon, Gyeonggi-do, 16419, Republic of Korea; Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Samsung Medical Center, Sungkyunkwan University, Seoul, 06351, Republic of Korea
| | - Gia Cac Chau
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, School of Medicine, Sungkyunkwan University, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Neeraj Kumar Mishra
- School of Pharmacy, Sungkyunkwan University, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - In Su Kim
- School of Pharmacy, Sungkyunkwan University, Suwon, Gyeonggi-do, 16419, Republic of Korea.
| | - Sung Hee Um
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, School of Medicine, Sungkyunkwan University, Suwon, Gyeonggi-do, 16419, Republic of Korea; Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Samsung Medical Center, Sungkyunkwan University, Seoul, 06351, Republic of Korea; Biomedical Institute Convergence at Sungkyunkwan University, Suwon, Gyeonggi-do, 16419, Republic of Korea.
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Tran NNQ, Chun KH. ROCK2-Specific Inhibitor KD025 Suppresses Adipocyte Differentiation by Inhibiting Casein Kinase 2. Molecules 2021; 26:4747. [PMID: 34443331 PMCID: PMC8401933 DOI: 10.3390/molecules26164747] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 07/30/2021] [Accepted: 08/02/2021] [Indexed: 11/16/2022] Open
Abstract
KD025, a ROCK2 isoform-specific inhibitor, has an anti-adipogenic activity which is not mediated by ROCK2 inhibition. To identify the target, we searched binding targets of KD025 by using the KINOMEscanTM screening platform, and we identified casein kinase 2 (CK2) as a novel target. KD025 showed comparable binding affinity to CK2α (Kd = 128 nM). By contrast, CK2 inhibitor CX-4945 and ROCK inhibitor fasudil did not show such cross-reactivity. In addition, KD025 effectively inhibited CK2 at a nanomolar concentration (IC50 = 50 nM). We examined if the inhibitory effect of KD025 on adipocyte differentiation is through the inhibition of CK2. Both CX-4945 and KD025 suppressed the generation of lipid droplets and the expression of proadipogenic genes Pparg and Cebpa in 3T3-L1 cells during adipocyte differentiation. Fasudil exerted no significant effect on the quantity of lipid droplets, but another ROCK inhibitor Y-27632 increased the expression of Pparg and Cebpa. Both CX-4945 and KD025 acted specifically in the middle stage (days 1-3) but were ineffective when treated at days 0-1 or the late stages, indicating that CX-4945 and KD025 may regulate the same target, CK2. The mRNA and protein levels of CK2α and CK2β generally decreased in 3T3-L1 cells at day 2 but recovered thereafter. Other well-known CK2 inhibitors DMAT and quinalizarin inhibited effectively the differentiation of 3T3-L1 cells. Taken together, the results of this study confirmed that KD025 inhibits ROCK2 and CK2, and that the inhibitory effect on adipocyte differentiation is through the inhibition of CK2.
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Affiliation(s)
| | - Kwang-Hoon Chun
- Gachon Institute of Pharmaceutical Sciences, College of Pharmacy, Gachon University, Incheon 21936, Korea;
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Zhao B, Liu M, Liu H, Xie J, Yan J, Hou X, Liu J. Zeaxanthin promotes browning by enhancing mitochondrial biogenesis through the PKA pathway in 3T3-L1 adipocytes. Food Funct 2021; 12:6283-6293. [PMID: 34047728 DOI: 10.1039/d1fo00524c] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Obesity is closely associated with maintaining mitochondrial homeostasis, and mitochondrial dysfunction can lead to systemic lipid metabolism disorders. Zeaxanthin (ZEA) is a kind of carotenoid with potent antioxidant activity and has been reported to promote mitochondrial biogenesis. Nevertheless, the molecular mechanism has not been explained. In this study, we first discovered that ZEA stimulated 3T3-L1 adipocyte browning by increasing the expression of specific markers (Cd137, Tbx1, Sirt1, Cidea, Ucp1, Tmem26, and Cited1), thereby reducing lipid accumulation. Besides, ZEA promoted mitochondrial biogenesis by increasing the expression of PRDM16, UCP1, NRF2, PGC-1α, and SIRT1. Moreover, the uncoupled oxygen consumption rate (OCR) of protons leaked in 3T3-L1 adipocytes was rapidly increased by ZEA treatment, which improved mitochondrial respiration and energy metabolism. Furthermore, we found that ZEA promotes browning by enhancing mitochondrial biogenesis partly through the protein kinase A (PKA) pathway. This study provided new insight into the promotion of browning and mitochondrial biogenesis by ZEA, suggesting that ZEA probably has potential therapeutic effects on obesity.
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Affiliation(s)
- Bailing Zhao
- National Engineering Laboratory for Wheat and Corn Deep Processing, Jilin Agricultural University, Changchun, Jilin 130118, China.
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Puckett D, Alquraishi M, Alani DS, Chahed S, Frankel VD, Donohoe D, Voy B, Whelan J, Bettaieb A. Zyflamend, a unique herbal blend, induces cell death and inhibits adipogenesis through the coordinated regulation of PKA and JNK. Adipocyte 2020; 9:454-471. [PMID: 32779962 PMCID: PMC7469463 DOI: 10.1080/21623945.2020.1803642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The prevalence of obesity and its comorbidities has sparked a worldwide concern to address rates of adipose tissue accrual. Recent studies have demonstrated a novel role of Zyflamend, a blend of natural herbal extracts, in regulating lipid metabolism in several cancer cell lines through the activation of the AMPK signalling pathway. Yet, the role of Zyflamend in adipogenic differentiation and lipid metabolism remains largely unexplored. The objective of this study is to investigate the effects of Zyflamend on white 3T3-MBX pre-adipocyte differentiation and elucidate the molecular mechanisms. We demonstrate that Zyflamend treatment altered cell cycle progression, attenuated proliferation, and increased cell death of 3T3-MBX pre-adipocytes. In addition, treatment with Zyflamend inhibited lipid accumulation during the differentiation of 3T3-MBX cells, consistent with decreased expression of lipogenic genes and increased lipolysis. Mechanistically, Zyflamend-induced alterations in adipogenesis were mediated, at least in part, through the activation of AMPK, PKA, and JNK. Inhibition of AMPK partially reversed Zyflamend-induced inhibition of differentiation, whereas the inhibition of either JNK or PKA fully restored adipocyte differentiation and decreased lipolysis. Taken together, the present study demonstrates that Zyflamend, as a novel anti-adipogenic bioactive mix, inhibits adipocyte differentiation through the activation of the PKA and JNK pathways. Abbreviation: 7-AAD: 7-amino-actinomycin D; ACC: acetyl-CoA carboxylase; AKT: protein kinase B; AMPK: AMP-activated protein kinase; ATGL: adipose triglyceride lipase; C/EBPα: CCAAT-enhancer binding protein alpha; DMEM: Dulbecco’s Modified Eagle Medium; DMSO: dimethyl sulphoxide; DTT: dithiothreitol; EGTA: ethylene glycol-bis-(2-aminoethyl)-N,N,N’,N’-tetraacetic acid; ERK: extracellular signal–regulated kinases; FASN: fatty acid synthase; FBS: foetal bovine serum; GLUT: glucose transporter; HSL: hormone-sensitive lipase; IR: insulin receptor; IRS: insulin receptor substrate; JNK: c-JUN N-terminal kinase; MGL: monoacylglycerol lipase; NaF: sodium fluoride; NF-κB: nuclear factor kappa-light-chain-enhancer of activated B cells; PBS: phosphate buffered- saline; PCB: pyruvate carboxylase; PDE: phosphodiesterase; PKA: protein kinase cAMP-dependent; PMSF: phenylmethylsulfonyl fluoride; PPARγ: perilipin peroxisome proliferator-activated receptor gamma; PREF-1: pre-adipocyte factor 1; PVDF: polyvinylidene fluoride; RIPA: radio-immunoprecipitation assay; SDS-PAGE: sodium dodecyl sulphate polyacrylamide gel electrophoresis; SEM: standard error of the mean; SOX9: suppressor of cytokine signalling 9; TGs: triacylglycerols.
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Affiliation(s)
- Dexter Puckett
- Department of Nutrition, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Mohammed Alquraishi
- Department of Nutrition, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Dina S. Alani
- Department of Nutrition, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Samah Chahed
- Department of Nutrition, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Victoria D. Frankel
- Department of Nutrition, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Dallas Donohoe
- Department of Nutrition, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Brynn Voy
- Tennessee Agricultural Experiment Station, University of Tennessee Institute of Agriculture, Knoxville, TN, USA
- Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, USA
| | - Jay Whelan
- Department of Nutrition, University of Tennessee Knoxville, Knoxville, TN, USA
- Tennessee Agricultural Experiment Station, University of Tennessee Institute of Agriculture, Knoxville, TN, USA
| | - Ahmed Bettaieb
- Department of Nutrition, University of Tennessee Knoxville, Knoxville, TN, USA
- Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, USA
- Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA
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The Gintonin-Enriched Fraction of Ginseng Regulates Lipid Metabolism and Browning via the cAMP-Protein Kinase a Signaling Pathway in Mice White Adipocytes. Biomolecules 2020; 10:biom10071048. [PMID: 32679738 PMCID: PMC7407952 DOI: 10.3390/biom10071048] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/05/2020] [Accepted: 07/13/2020] [Indexed: 12/20/2022] Open
Abstract
Obesity is a major health concern and is becoming an increasingly serious societal problem worldwide. The browning of white adipocytes has received considerable attention because of its potential protective effect against obesity-related metabolic disease. The gintonin-enriched fraction (GEF) is a non-saponin, glycolipoprotein component of ginseng that is known to have neuroprotective and anti-inflammatory effects. However, the anti-obesity and browning effects of GEF have not been explored to date. Therefore, we aimed to determine whether GEF has a preventive effect against obesity. We differentiated 3T3-L1 cells and mouse primary subcutaneous adipocytes for 8 days in the presence or absence of GEF, and then measured the expression of intermediates in signaling pathways that regulate triglyceride (TG) synthesis and browning by Western blotting and immunofluorescence analysis. We found that GEF reduced lipid accumulation by reducing the expression of pro-adipogenic and lipogenic factors, and increased lipolysis and thermogenesis, which may be mediated by an increase in the phosphorylation of protein kinase A. These findings suggest that GEF may induce fat metabolism and energy expenditure in white adipocytes and therefore may represent a potential treatment for obesity.
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cAMP/Protein Kinase A Signaling Inhibits Dlx5 Expression via Activation of CREB and Subsequent C/EBPβ Induction in 3T3-L1 Preadipocytes. Int J Mol Sci 2018; 19:ijms19103161. [PMID: 30322210 PMCID: PMC6213991 DOI: 10.3390/ijms19103161] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 10/05/2018] [Accepted: 10/10/2018] [Indexed: 11/17/2022] Open
Abstract
Distal-less homeobox 5 (Dlx5) is a negative regulator of adipogenesis. Dlx5 expression is decreased by adipogenic stimuli, but the mechanisms of Dlx5 downregulation by adipogenic stimuli have not yet been determined. Here, we tested the impact of cAMP/PKA (protein kinase A) signaling induced by 3-isobutyl-1 methyl xanthine (IBMX), forskolin, and 8-CPT-cAMP on the expression of Dlx5 in 3T3-L1 preadipocytes. Significant downregulation of Dlx5 mRNA expression and protein production levels were observed via cAMP/PKA-dependent signaling. Forced expression of cAMP-responsive element-binding protein (CREB) and CCAAT/enhancer-binding protein β (C/EBPβ) was sufficient for downregulation of Dlx5 expression and revealed that CREB functions upstream of C/EBPβ. In addition, C/EBPβ knockdown by siRNA rescued Dlx5 expression in IBMX-treated 3T3-L1 preadipocytes. Luciferase assays using a Dlx5-luc-2935 reporter construct demonstrated the requirement of the Dlx5 promoter region, ranging from −774 to −95 bp that contains two putative C/EBPβ binding elements (site-1: −517 to −510 bp and site-2: −164 to −157 bp), in the suppression of Dlx5 transcription. Consequently, chromatin immunoprecipitation analysis confirmed the importance of site-1, but not site-2, in C/EBPβ binding and transcriptional suppression of Dlx5. In conclusion, we elucidated the underling mechanism of Dlx5 downregulation in IBMX-induced adipogenesis. IBMX activated cAMP/PKA/CREB signaling and subsequently upregulated C/EBPβ, which binds to the Dlx5 promoter to suppress Dlx5 transcription.
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Ca v1.2 channel current block by the PKA inhibitor H-89 in rat tail artery myocytes via a PKA-independent mechanism: Electrophysiological, functional, and molecular docking studies. Biochem Pharmacol 2017; 140:53-63. [PMID: 28583845 DOI: 10.1016/j.bcp.2017.05.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Accepted: 05/31/2017] [Indexed: 12/12/2022]
Abstract
To characterize the role of cAMP-dependent protein kinase (PKA) in regulating vascular Ca2+ current through Cav1.2 channels [ICa1.2], we have documented a marked capacity of the isoquinoline H-89, widely used as a PKA inhibitor, to reduce current amplitude. We hypothesized that the ICa1.2 inhibitory activity of H-89 was mediated by mechanisms unrelated to PKA inhibition. To support this, an in-depth analysis of H-89 vascular effects on both ICa1.2 and contractility was undertaken by performing whole-cell patch-clamp recordings and functional experiments in rat tail main artery single myocytes and rings, respectively. H-89 inhibited ICa1.2 with a pIC50 (M) value of about 5.5, even under conditions where PKA activity was either abolished by both the PKA antagonists KT5720 and protein kinase inhibitor fragment 6-22 amide or enhanced by the PKA stimulators 6-Bnz-cAMP and 8-Br-cAMP. Inhibition of ICa1.2 by H-89 appeared almost irreversible upon washout, was charge carrier- and voltage-dependent, and antagonised by the Cav1.2 channel agonist (S)-(-)-Bay K 8644. H-89 did not alter both potency and efficacy of verapamil, did not affect current kinetics or voltage-dependent activation, while shifting to the left the 50% voltage of inactivation in a concentration-dependent manner. H-89 docked at the α1C subunit in a pocket region close to that of (S)-(-)-Bay K 8644 docking, forming a hydrogen bond with the same, key amino acid residue Tyr-1489. Finally, both high K+- and (S)-(-)-Bay K 8644-induced contractions of rings were fully reverted by H-89. In conclusion, these results indicate that H-89 inhibited vascular ICa1.2 and, consequently, the contractile function through a PKA-independent mechanism. Therefore, caution is recommended when interpreting experiments where H-89 is used to inhibit vascular smooth muscle PKA.
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Key Words
- (S)-(-)-Bay K 8644 ((S)-(-)-methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl)pyridine-5-carboxylate) (PubChem CID: 6603728)
- 8-Bromoadenosine 3′,5′-cyclic monophosphate (PubChem CID: 32014)
- Ca(V)1.2 channel
- H-89
- H-89 (N-[2-[[3-(4-bromophenyl)-2-propen-1-yl]amino]ethyl]-5-isoquinolinesulfonamide) (PubChem CID: 449241)
- KT5720 ((9R,10S,12S)-2,3,9,10,11,12-hexahydro-10-hydroxy-9-methyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3′,2′,1′-kl]pyrrolo[3,4-][1,6]benzodiazocine-10-carboxylic acid, hexyl ester) (PubChem CID: 3844)
- Molecular docking
- N(6)-Benzoyladenosine-3′,5′-cyclic monophosphate (PubChem CID: 17757210)
- PKA
- PKA inhibitor fragment 6-22 (PubChem CID: 16155227)
- Patch-clamp
- Rat tail artery
- Verapamil (PubChem CID: 62969)
- nifedipine (PubChem CID: 4485)
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Li T, Mo H, Chen W, Li L, Xiao Y, Zhang J, Li X, Lu Y. Role of the PI3K-Akt Signaling Pathway in the Pathogenesis of Polycystic Ovary Syndrome. Reprod Sci 2016; 24:646-655. [PMID: 27613818 DOI: 10.1177/1933719116667606] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
This review aimed to focus on the recent progress of the understanding of the role of phosphatidylinositol 3-kinase (PI3K) in polycystic ovary syndrome (PCOS). In recent years, it has been increasingly recognized that PI3K plays an important role in PCOS whose pathogenesis is unclear. However, research continues into revealing the details of how PI3Ks are involved in developing PCOS. Previous studies have shown that activation of the PI3K-protein kinase B (Akt) signaling pathway has important effects on insulin resistance and endometrial cancer. Knowledge of the action of PI3K in PCOS might provide valuable information to further validate the pathogenesis of PCOS and suggest new methods of treatment.
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Affiliation(s)
- Tiantian Li
- 1 Department of Obstetrics and Gynecology, Guangdong Women and Children Hospital, Guangzhou Medical University, Guangzhou, China
| | - Hui Mo
- 2 Laboratory of Chinese Medicine Quality Research, Macau University of Science and Technology, Macau, China
| | - Wenfeng Chen
- 1 Department of Obstetrics and Gynecology, Guangdong Women and Children Hospital, Guangzhou Medical University, Guangzhou, China
| | - Li Li
- 1 Department of Obstetrics and Gynecology, Guangdong Women and Children Hospital, Guangzhou Medical University, Guangzhou, China.,2 Laboratory of Chinese Medicine Quality Research, Macau University of Science and Technology, Macau, China
| | - Yao Xiao
- 2 Laboratory of Chinese Medicine Quality Research, Macau University of Science and Technology, Macau, China
| | - Jing Zhang
- 3 Guangzhou Family Planning Specialty Hospital, Guangzhou, China
| | - Xiaofang Li
- 1 Department of Obstetrics and Gynecology, Guangdong Women and Children Hospital, Guangzhou Medical University, Guangzhou, China
| | - Ying Lu
- 1 Department of Obstetrics and Gynecology, Guangdong Women and Children Hospital, Guangzhou Medical University, Guangzhou, China
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PKA Inhibitor H89 (N-[2-p-bromocinnamylamino-ethyl]-5-isoquinolinesulfonamide) Attenuates Synaptic Dysfunction and Neuronal Cell Death following Ischemic Injury. Neural Plast 2015; 2015:374520. [PMID: 26448879 PMCID: PMC4584069 DOI: 10.1155/2015/374520] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 02/27/2015] [Accepted: 03/17/2015] [Indexed: 11/26/2022] Open
Abstract
The cyclic AMP-dependent protein kinase (PKA), which activates prosurvival signaling proteins, has been implicated in the expression of long-term potentiation and hippocampal long-term memory. It has come to light that H89 commonly known as the PKA inhibitor have diverse roles in the nervous system that are unrelated to its role as a PKA inhibitor. We have investigated the role of H89 in ischemic and reperfusion injury. First, we examined the expression of postsynaptic density protein 95 (PSD95), microtubule-associated protein 2 (MAP2), and synaptophysin in mouse brain after middle cerebral artery occlusion injury. Next, we examined the role of H89 pretreatment on the expression of brain-derived neurotrophic factor (BDNF), PSD95, MAP2, and the apoptosis regulators Bcl2 and cleaved caspase-3 in cultured neuroblastoma cells exposed to hypoxia and reperfusion injury. In addition, we investigated the alteration of AKT activation in H89 pretreated neuroblastoma cells under hypoxia and reperfusion injury. The data suggest that H89 may contribute to brain recovery after ischemic stroke by regulating neuronal death and proteins related to synaptic plasticity.
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Zhang L, Grennan-Jones F, Draman MS, Lane C, Morris D, Dayan CM, Tee AR, Ludgate M. Possible targets for nonimmunosuppressive therapy of Graves' orbitopathy. J Clin Endocrinol Metab 2014; 99:E1183-90. [PMID: 24758182 DOI: 10.1210/jc.2013-4182] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
CONTEXT Graves' orbitopathy (GO) is caused by expansion of the orbital contents by excess adipogenesis and overproduction of hyaluronan (HA). Immunosuppressive and antiinflammatory treatments of GO are not always effective and can have side effects, whereas targeting GO-associated tissue remodeling might be a more logical therapeutic strategy. Previously we reported that signaling cascades through IGF1 receptor and thyrotropin receptor within orbital preadipocytes/fibroblasts drove adipogenesis and HA production. Our current study combined the stimulation of IGF1 receptor and thyrotropin receptor increase of HA accumulation, which we hypothesize is by activation of phosphatidylinositol 3-kinase (PI3K)-1A/PI3K1B, respectively. The central aim of this study was to investigate whether PI3K/mammalian target of rapamycin complex 1 (mTORC1) inhibitors affected adipogenesis and/or HA production within orbital preadipocyte/fibroblasts. METHODS Human orbital preadipocytes were treated with/without inhibitors, LY294002 (PI3K1A/mTORC1), AS-605240 (PI3K1B), or PI103 (PI3K1A/mTORC1) in serum-free medium for 24 hours or cultured in adipogenic medium for 15 days. Quantitative PCR was used to measure hyaluronan synthases (HAS2) transcripts and the terminal adipogenesis differentiation marker lipoprotein lipase. HA accumulation in the medium was measured by an ELISA. RESULTS Unlike AS-605240, both LY294002 (10 μM) and PI-103 (5 μM) significantly decreased HAS2 transcripts/HA accumulation and adipogenesis. Because PI-103 and LY294002 are dual PI3K/mTOR inhibitors, we investigated the inhibition of mTORC1 (rapamycin 100 nM), which significantly decreased adipogenesis but had no effect on HAS2 transcripts/HA, implicating PI3K-1A in the latter. CONCLUSIONS The combined inhibition of PI3K1A and mTORC1 signaling in vitro decreased both HA accumulation and adipogenesis. Because PI3K and mTOR inhibitors are clinically used to treat other conditions, they have the potential to be repositioned to be used as an alternative nonimmunosuppressive therapy of GO.
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Affiliation(s)
- L Zhang
- Institute of Molecular and Experimental Medicine (L.Z., F.G.-J., M.S.D., C.M.D., M.L.), Department of Medical Genetics (A.R.T.), Institute of Cancer and Genetics, School of Medicine, Cardiff University, and Department of Ophthalmology (C.L., D.M.), Cardiff and Vale University Health Board, Heath Park, Cardiff CF14 4XN, United Kingdom
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Wakayama S, Haque A, Koide N, Kato Y, Odkhuu E, Bilegtsaikhan T, Naiki Y, Komatsu T, Yoshida T, Yokochi T. Lipopolysaccharide impairs insulin sensitivity via activation of phosphoinositide 3-kinase in adipocytes. Immunopharmacol Immunotoxicol 2014; 36:145-9. [PMID: 24506665 DOI: 10.3109/08923973.2014.887096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The effect of lipopolysaccharide (LPS) on insulin sensitivity in adipocytes were examined by using differentiated 3T3-L1 adipocytes. Insulin-mediated activation of insulin receptor substrate (IRS) 1/2 was inhibited in LPS-pretreated adipocytes and IRS1/2-mediated Akt activation was also attenuated in those cells. LPS inhibited activation of glycogen synthase kinase 3 as a negative regulator of glycogenesis and impaired the glycogen synthesis in response to insulin. LPS-induced activation of phosphoinositide 3-kinase (PI3K) in adipocytes. Involvement of suppressor of cytokine signaling 3 (SOCS3) in LPS-induced IRS1/2 inhibition was excluded. Considering that both insulin and LPS were able to activate the PI3K/Akt signaling pathway, LPS was suggested to impair insulin sensitivity of adipocytes through down-regulating insulin-mediated PI3K/Akt activation.
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12
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Lee SH, Huang H, Choi K, Lee DH, Shi J, Liu T, Chun KH, Seo JA, Lima IS, Zabolotny JM, Wei L, Kim YB. ROCK1 isoform-specific deletion reveals a role for diet-induced insulin resistance. Am J Physiol Endocrinol Metab 2014; 306:E332-43. [PMID: 24326423 PMCID: PMC3920011 DOI: 10.1152/ajpendo.00619.2013] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Rho kinase (ROCK) isoforms regulate insulin signaling and glucose metabolism negatively or positively in cultured cell lines and skeletal muscle. However, the in vivo function of the ROCK1 isoform in adipose tissue has not been addressed. To determine the specific role of the adipose ROCK1 isoform in the development of insulin resistance and obesity, mice lacking ROCK1 in adipose tissue globally or selectively were studied. Here, we show that insulin's ability to activate IRS-1/PI3K/Akt signaling was greatly enhanced in adipose tissue of ROCK1(-/-) mice compared with wild-type mice. These effects resulted from the inhibitory effect of ROCK1 on insulin receptor action, as evidenced by the fact that IR tyrosine phosphorylation was abolished in ROCK1(-/-) MEF cells when ROCK1 was reexpressed. Consistently, adipose-specific disruption of ROCK1 increased IR tyrosine phosphorylation in adipose tissue and modestly improved sensitivity to insulin in obese mice induced by high-fat feeding. This effect is independent of any changes in adiposity, number or size of adipocytes, and metabolic parameters, including glucose, insulin, leptin, and triglyceride levels, demonstrating a minimal effect of adipose ROCK1 on whole body metabolism. Enzymatic activity of ROCK1 in adipose tissue remained ∼50%, which likely originated from the fraction of stromal vascular cells, suggesting involvement of these cells for adipose metabolic regulation. Moreover, ROCK isoform activities were increased in adipose tissue of diet-induced or genetically obese mice. These data suggest that adipose ROCK1 isoform plays an inhibtory role for the regulation of insulin sensitivity in diet-induced obesity in vivo.
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Affiliation(s)
- Seung-Hwan Lee
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
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13
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Gabrielli M, Martini CN, Brandani JN, Iustman LJR, Romero DG, del C Vila M. Exchange protein activated by cyclic AMP is involved in the regulation of adipogenic genes during 3T3-L1 fibroblasts differentiation. Dev Growth Differ 2014; 56:143-51. [PMID: 24444094 DOI: 10.1111/dgd.12114] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 11/13/2013] [Accepted: 11/25/2013] [Indexed: 12/01/2022]
Abstract
Adipogenesis is stimulated in 3T3-L1 fibroblasts by a combination of insulin, dexamethasone and isobutylmethylxanthine, IBMX, (I+D+M). Two transcription factors are important for the acquisition of the adipocyte phenotype, C/EBP beta (CCAT enhancer-binding protein beta) and PPAR gamma (peroxisome proliferator-activated receptor gamma). IBMX increases cAMP content, which can activate protein kinase A (PKA) and/or EPAC (exchange protein activated by cAMP). To investigate the importance of IBMX in the differentiation mixture, we first evaluated the effect of the addition of IBMX on the increase of C/EBP beta and PPAR gamma and found an enhancement of the amount of both proteins. IBMX addition (I+D+M) or its replacement with a cAMP analogue, dibutyryl-cAMP or 8-(4-chlorophenylthio)-2-O'-methyl-cAMP (8CPT-2-Me-cAMP), the latter activates EPAC and not PKA, remarkably increased PPAR gamma mRNA. However, neither I+D nor any of the inducers alone, increased PPAR gamma mRNA to a similar extent, suggesting the importance of the presence of both IBMX and I+D. It was also found that the addition of IBMX or 8CPT-2-Me-cAMP was able to increase the content of C/EBP beta with respect to I+D. In agreement with these findings, a microarray analysis showed that the presence of either 8CPT-2-Me-cAMP or IBMX in the differentiation mixture was able to upregulate PPAR gamma and PPAR gamma-activated genes as well as other genes involved in lipid metabolism. Our results prove the involvement of IBMX-cAMP-EPAC in the regulation of adipogenic genes during differentiation of 3T3-L1 fibroblasts and therfore contributes to elucidate the role of cyclic AMP in this process.
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Affiliation(s)
- Matías Gabrielli
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, Buenos Aires, 1428, Argentina
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14
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Huang H, Lee DH, Zabolotny JM, Kim YB. Metabolic actions of Rho-kinase in periphery and brain. Trends Endocrinol Metab 2013; 24:506-14. [PMID: 23938132 PMCID: PMC3783562 DOI: 10.1016/j.tem.2013.06.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Revised: 06/11/2013] [Accepted: 06/13/2013] [Indexed: 01/01/2023]
Abstract
Obesity has increased at an alarming rate in recent years and is now a worldwide public health problem. Elucidating the mechanisms behind the metabolic dysfunctions associated with obesity is of high priority. The metabolic function of Rho-kinase (Rho-associated coiled-coil-containing kinase; ROCK) has been the subject of a great deal of investigation in metabolic-related diseases. It appears that inhibition of ROCK activity is beneficial for the treatment of a wide range of cardiovascular-related diseases. However, recent studies with genetic models of ROCK demonstrate that ROCK plays a positive role in insulin and leptin signaling. Here we discuss the newly identified functions of ROCK in regulating glucose and energy metabolism, with particular emphasis on metabolic actions of insulin and leptin.
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Affiliation(s)
- Hu Huang
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, and Harvard Medical School, Boston, MA 02215, USA
| | - Dae-Ho Lee
- Department of Internal Medicine, School of Medicine, Wonkwang University, Iksan, Korea 570-749
| | - Janice M Zabolotny
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, and Harvard Medical School, Boston, MA 02215, USA
| | - Young-Bum Kim
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, and Harvard Medical School, Boston, MA 02215, USA
- Lee Gil Ya Cancer & Diabetes Institute, Graduate Schools of Medicine, Gachon University of Medicine & Science, Incheon, Korea 406-799
- Corresponding author: Young-Bum Kim, Ph.D., Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, Phone: (617) 735-3216, Fax: (617) 735-3323,
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15
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Yamaguchi M, Baile CA, Zhu S, Shoji M. Bioactive flavonoid p-hydroxycinnamic acid stimulates osteoblastogenesis and suppresses adipogenesis in bone marrow culture. Cell Tissue Res 2013; 354:743-50. [PMID: 24026435 PMCID: PMC3832765 DOI: 10.1007/s00441-013-1707-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 07/16/2013] [Indexed: 11/24/2022]
Abstract
The bioactive flavonoid p-hydroxycinnamic acid (HCA), which is an intermediate-metabolic substance in plants and fruits, is synthesized from tyrosine. The biological effect of HCA is poorly understood. Among cinnamic acid and its related compounds, HCA has a specific-anabolic effect on bone, being found to stimulate osteoblastogenesis and to inhibit osteoclastogenesis through the suppression of NF-κB signaling, thereby preventing bone loss. Bone marrow mesenchymal stem cells give rise to ostoblasts and adipocytes. HCA might therefore have effects on osteoblastogenesis and adipogenesis in bone marrow culture. This study demonstrates (1) that HCA has stimulatory effects on osteoblastogenesis and mineralization and suppressive effects on adipogenesis in mouse bone marrow culture and (2) that HCA depresses adipogenesis in mouse 3T3-L1 preadipocytes in vitro. Such effects of HCA might be involved in the differentiation of mesenchymal stem cells.
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Affiliation(s)
- Masayoshi Yamaguchi
- Department of Hematology and Biomedical Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, 30322, USA,
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16
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Haridas Nidhina PA, Poulose N, Gopalakrishnapillai A. Vanillin induces adipocyte differentiation in 3T3-L1 cells by activating extracellular signal regulated kinase 42/44. Life Sci 2011; 88:675-80. [PMID: 21315734 DOI: 10.1016/j.lfs.2011.02.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2010] [Revised: 12/27/2010] [Accepted: 01/27/2011] [Indexed: 10/18/2022]
Abstract
AIMS To investigate the effect of vanillin, a dietary component, on adipocyte differentiation and the mechanism involved in the process using 3T3-L1 murine preadipocytes. MAIN METHODS The effect of vanillin on adipocyte differentiation was detected by Oil Red O analysis. The activation of extracellular signal regulated kinase 42/44 (ERK 42/44), Akt, expression of the key regulator of adipocyte differentiation peroxisome proliferators-activated receptor (PPARγ) and its target gene glucose transporter 4 (GLUT4) were detected by western blotting. Glucose uptake assay was used to determine the insulin sensitivity of adipocytes differentiated by vanillin treatment. To confirm the role of ERK 42/44 and Akt, Oil Red O analysis was performed with cells differentiated in the presence or absence of ERK inhibitor U0126 or Akt kinase 1/2 inhibitor. KEY FINDINGS Vanillin induced adipocyte differentiation in 3T3-L1 cells in a dose dependent manner and also increased the expression levels of PPARγ and its target gene GLUT4. The adipocytes differentiated by vanillin exhibited insulin sensitivity as demonstrated by a significant increase in glucose uptake. Vanillin treatment activated the phosphorylation of ERK 42/44 during the initial phase of adipocyte differentiation but there was no significant change in the Akt phosphorylation status. SIGNIFICANCE The data show that vanillin induces adipocyte differentiation in 3T3-L1 cells by activating ERK42/44 and these adipocytes are insulin sensitive in nature.
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Affiliation(s)
- Pachakkil A Haridas Nidhina
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Amritapuri, Clappana P.O, Kollam, Kerala, 690525, India
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17
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Gao S, Ito H, Murakami M, Yoshida K, Tagawa Y, Hagiwara K, Takagi A, Kojima T, Suzuki M, Banno Y, Ohguchi K, Nozawa Y, Murate T. Mechanism of increased PLD1 gene expression during early adipocyte differentiation process of mouse cell line 3T3-L1. J Cell Biochem 2010; 109:375-82. [PMID: 19950202 DOI: 10.1002/jcb.22414] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A mouse cell line 3T3-L1 is differentiated into adipocytes when treated with an inducer cocktail (IDX) (insulin, dexametahsone, and a cAMP phosphodiesterase inhibitor of isobutyl-methylxanthine (IBMX)). Here, we report that PLD1, but not PLD2, mRNA and protein increased during the early differentiation process. Our analysis shows that IDX resulted in a sequential induction of C/EBPbeta, PLD1, and C/EBPalpha which is a key transcription factor of late adipocyte differentiation. Among the three inducers, IBMX + any other inducer induced mild adipocyte differentiation, whereas insulin + dexamethasone did not. IBMX increased PLD1 but not PLD2 mRNA. Forskolin, an adenylate cyclase activator, and dbcAMP also increased PLD1 mRNA, suggesting the cellular cAMP as the inducer of both adipocyte differentiation and PLD1 transcription. We focused on the regulatory mechanism of PLD1 transcription during this differentiation process. IDX or a combination of inducers including IBMX increased PLD1 promoter activity, which is consistent with mRNA analysis. Promoter analysis identified two adjacent C/EBP motifs located between -338 and -231 bp from the first exon as the IBMX responsive elements. Furthermore, overexpression of C/EBPbeta, but not C/EBPalpha, increased PLD1 mRNA and PLD1 5' promoter activity. EMSA and chromatin immunoprecipitation assay confirmed the direct binding of C/EBPbeta, but not C/EBPalpha, to these C/EBP motifs of PLD1 5' promoter. Our results show that PLD1 is a target gene of C/EBPbeta through the increased cellular cAMP during early adipocyte differentiation of 3T3-L1 cells.
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Affiliation(s)
- Siqiang Gao
- Department of Medical Technology, Nagoya University Graduate School of Health Sciences, Nagoya, Japan
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18
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Martini CN, Plaza MV, Vila MDC. PKA-dependent and independent cAMP signaling in 3T3-L1 fibroblasts differentiation. Mol Cell Endocrinol 2009; 298:42-7. [PMID: 19010385 DOI: 10.1016/j.mce.2008.10.023] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 10/01/2008] [Accepted: 10/02/2008] [Indexed: 10/21/2022]
Abstract
Adipogenesis is stimulated in 3T3-L1 fibroblast by a combination of insulin, dexamethasone, and methylisobutylxanthine (MIX). Mitotic clonal expansion (MCE) precedes differentiation of 3T3-L1 fibroblast to adipocytes. MIX increases cAMP content, which is the activator of protein kinase A (PKA). However, PKA-independent cAMP signaling has also been described. In this paper, it was found that H89, an inhibitor of PKA, was able to block MCE but not differentiation of 3T3-L1 fibroblast. Consistently, MCE did not occur in the absence of MIX in the differentiation mixture but was recovered by overexpression of a catalytic subunit of PKA. In addition, the transfection of 3T3-L1 fibroblast with a dominant-negative mutant of PKA inhibited MCE. On the other hand, differentiation of 3T3-L1 fibroblast to adipocytes did not occur when MIX was not present in the differentiation mixture and it could not be recovered by overexpression of a catalytic subunit of PKA. Differentiation was restored by addition of either dibutyryl-cAMP (db-cAMP) or 8 CPT-2 Me-cAMP. The latter activates cAMP-EPAC but not PKA signaling. These results indicate that cAMP-PKA-independent signaling, is required for 3T3-L1 fibroblasts differentiation to adipocytes and MIX signaling through cAMP-PKA is necessary for MCE, although MCE is not essential for adipogenesis.
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Affiliation(s)
- Claudia N Martini
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
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Ginsenosides Rb1 and Rg1 suppress triglyceride accumulation in 3T3-L1 adipocytes and enhance beta-cell insulin secretion and viability in Min6 cells via PKA-dependent pathways. Biosci Biotechnol Biochem 2008; 72:2815-23. [PMID: 18997435 DOI: 10.1271/bbb.80205] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Ginseng root is known to induce anti-diabetic activity, but the key components involved are unknown. We investigated which major ginsenosides in ginseng enhanced glucose homeostasis by in vitro studies. Rb1 and Rg1 reduced the triglyceride accumulation in 3T3-L1 adipocytes by activating PKA with increased intracellular cAMP. However, the insulin-stimulated glucose uptake was enhanced by Rb1 and Rg1 via activation of phosphatidylinositol-3 kinase. Rb1 and Rg1 promoted glucose-stimulated insulin secretion and cell viability in Min6 cells through PKA which augmented IRS2 expression to enhance insulin/IGF-1 signaling. These results suggest that Rb1 and Rg1 improved glucose homeostasis through the activation of a PKA like glucagon-like peptide-1 receptor agonist.
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Ayala-Sumuano JT, Valle CVD, Beltrán-Langarica A, Hernández JM, Kuri-Harcuch W. Adipogenic genes on induction and stabilization of commitment to adipose conversion. Biochem Biophys Res Commun 2008; 374:720-4. [DOI: 10.1016/j.bbrc.2008.07.127] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 07/18/2008] [Indexed: 10/21/2022]
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Cyclic AMP (cAMP)-mediated stimulation of adipocyte differentiation requires the synergistic action of Epac- and cAMP-dependent protein kinase-dependent processes. Mol Cell Biol 2008; 28:3804-16. [PMID: 18391018 DOI: 10.1128/mcb.00709-07] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cyclic AMP (cAMP)-dependent processes are pivotal during the early stages of adipocyte differentiation. We show that exchange protein directly activated by cAMP (Epac), which functions as a guanine nucleotide exchange factor for the Ras-like GTPases Rap1 and Rap2, was required for cAMP-dependent stimulation of adipocyte differentiation. Epac, working via Rap, acted synergistically with cAMP-dependent protein kinase (protein kinase A [PKA]) to promote adipogenesis. The major role of PKA was to down-regulate Rho and Rho-kinase activity, rather than to enhance CREB phosphorylation. Suppression of Rho-kinase impaired proadipogenic insulin/insulin-like growth factor 1 signaling, which was restored by activation of Epac. This interplay between PKA and Epac-mediated processes not only provides novel insight into the initiation and tuning of adipocyte differentiation, but also demonstrates a new mechanism of cAMP signaling whereby cAMP uses both PKA and Epac to achieve an appropriate cellular response.
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22
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Oksvold MP, Funderud A, Kvissel AK, Skarpen E, Henanger H, Huitfeldt HS, Skålhegg BS, Ørstavik S. Epidermal growth factor receptor levels are reduced in mice with targeted disruption of the protein kinase A catalytic subunit. BMC Cell Biol 2008; 9:16. [PMID: 18380891 PMCID: PMC2324083 DOI: 10.1186/1471-2121-9-16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Accepted: 04/01/2008] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Epidermal Growth Factor Receptor (EGFR) is a key target molecule in current treatment of several neoplastic diseases. Hence, in order to develop and improve current drugs targeting EGFR signalling, an accurate understanding of how this signalling pathway is regulated is required. It has recently been demonstrated that inhibition of cAMP-dependent protein kinase (PKA) induces a ligand-independent internalization of EGFR. Cyclic-AMP-dependent protein kinase consists of a regulatory dimer bound to two catalytic subunits. RESULTS We have investigated the effect on EGFR levels after ablating the two catalytic subunits, Calpha and Cbeta in two different models. The first model used targeted disruption of either Calpha or Cbeta in mice whereas the second model used Calpha and Cbeta RNA interference in HeLa cells. In both models we observed a significant reduction of EGFR expression at the protein but not mRNA level. CONCLUSION Our results suggest that PKA may represent a target that when manipulated can maintain EGFR protein levels at the single cell level as well as in intact animals.
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Affiliation(s)
- Morten P Oksvold
- Institute of Pathology, Rikshospitalet University Hospital, University of Oslo, Norway
| | - Ane Funderud
- Institute for Basic Medical Sciences, Department of Nutrition, University of Oslo Medical School, Norway
| | - Anne-Katrine Kvissel
- Institute for Basic Medical Sciences, Department of Nutrition, University of Oslo Medical School, Norway
| | - Ellen Skarpen
- Institute of Pathology, Rikshospitalet University Hospital, University of Oslo, Norway
| | - Heidi Henanger
- Institute for Basic Medical Sciences, Department of Nutrition, University of Oslo Medical School, Norway
| | - Henrik S Huitfeldt
- Institute of Pathology, Rikshospitalet University Hospital, University of Oslo, Norway
| | - Bjørn S Skålhegg
- Institute for Basic Medical Sciences, Department of Nutrition, University of Oslo Medical School, Norway
| | - Sigurd Ørstavik
- Institute for Basic Medical Sciences, Department of Nutrition, University of Oslo Medical School, Norway
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Zaballos MA, Garcia B, Santisteban P. Gbetagamma dimers released in response to thyrotropin activate phosphoinositide 3-kinase and regulate gene expression in thyroid cells. Mol Endocrinol 2008; 22:1183-99. [PMID: 18202153 DOI: 10.1210/me.2007-0093] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Signaling by TSH through its receptor leads to the dissociation of trimeric G proteins into Galpha and Gbetagamma. Galphas activates adenylyl cyclase, which increases cAMP levels that induce several effects in the thyroid cell, including transcription of the sodium-iodide symporter (NIS) gene through a mechanism involving Pax8 binding to the NIS promoter. Much less is known about the function of Gbetagamma in thyroid differentiation, and therefore we studied their role in TSH signaling. Gbetagamma overexpression inhibits NIS promoter activation and reduces NIS protein accumulation in response to TSH and forskolin. Conversely, inhibition of Gbetagamma-dependent pathways increases NIS promoter activity elicited by TSH but does not modify forskolin-induced activation. Gbetagamma dimers are being released from the Gs subfamily of proteins, because cholera toxin mimics the effects elicited by TSH, whereas pertussis toxin has no effect on NIS promoter activity. We also found that TSH stimulates Akt phosphorylation in a phosphoinositide 3-kinase (PI3K)-dependent and cAMP-independent manner. This is mediated by Gbetagamma, because its overexpression or specific sequestration, respectively, increased or reduced phosphorylated Akt levels upon TSH stimulation. Gbetagamma sequestration increases NIS protein levels induced by TSH and Pax8 binding to the NIS promoter, which is also increased by PI3K inhibition. This is, at least in part, caused by Gbetagamma-mediated Pax8 exclusion from the nucleus that is attenuated when PI3K activity is blocked. These data unequivocally demonstrate that Gbetagamma released by TSH action stimulate PI3K, inhibiting NIS gene expression in a cAMP-independent manner due to a decrease in Pax8 binding to the NIS promoter.
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Affiliation(s)
- Miguel A Zaballos
- Instituto de Investigaciones Biomedicas Alberto Sols, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28029 Madrid, Spain
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