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Kawaji N, Yoshida A, Motoyashiki T, Morita T, Ueki H. Anti-leptin receptor antibody mimics the stimulation of lipolysis induced by leptin in isolated mouse fat pads. J Lipid Res 2001; 42:1671-7. [PMID: 11590224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
An anti-leptin receptor polyclonal antibody (receptor antibody), as well as leptin, stimulated the release of free fatty acids from isolated mouse fat pads in a time-dependent manner. Following a 90-min incubation, maximal lipolysis was observed at 6 microg/ml receptor antibody and 0.1 nM leptin. The receptor antibody did not show any additive effect to the stimulation of lipolysis induced by leptin, suggesting that they exert their actions through a similar mechanism involving the leptin receptor. N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), quin 2-AM, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), and neomycin sulfate (neomycin) all potently inhibited the stimulation of lipolysis by the receptor antibody and leptin. Short-term incubation of the fat pads with the receptor antibody or leptin showed a transient increase in the cellular content of cAMP and myo-inositol 1,4,5-trisphosphate (IP3) in similar concentrations to the free fatty acid release. Quin 2-AM and W-7 also inhibited the increase in cAMP content, suggesting that a Ca(2)+/calmodulin-dependent process may be involved in a part of the mechanism in which the receptor antibody and leptin exert their effects. The increase in cellular IP3 content via phosphoinositide-specific phospholipase C (PLC) sensitive to neomycin appears to be a primary step to initiate intracellular events. Both the receptor antibody and leptin may stimulate the lipolysis through mechanisms involving a transient increase in the cellular IP3 content followed by cAMP production, which leads to the activation of cAMP-dependent protein kinase.
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Affiliation(s)
- N Kawaji
- Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Fukuyama, Hiroshima 729-0292, Japan
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Abstract
When isolated mouse fat pads were incubated with orthovanadate (vanadate) or insulin for up to 4 h, the leptin secretion into the medium was decreased by vanadate and increased by insulin. Propranolol, a nonspecific antagonist of beta-adrenergic receptors, bupranorol, a specific antagonist of beta3-adrenergic receptor, and H-89, an inhibitor of cAMP-dependent protein kinase (PKA) all inhibited the decrease by vanadate to various extents. In contrast, no inhibition was observed with specific antagonists of beta1- and beta2-adrenergic receptors or with inhibitors of protein kinase C and Ca/calmodulin kinase. Short-term incubation of the fat pads with vanadate showed a transient increase in the cellular cAMP content; this increase was inhibited by propranolol and bupranolol. Vanadate had no effect on the incorporation of [3H]-leucine into proteins of the fat pads with a 4-h incubation, although insulin stimulated the incorporation. The decreasing effect of vanadate on the leptin secretion seems to be independent of the regulation of protein synthesis. These results suggest that vanadate decreases the leptin secretion through mechanisms involving the increase in cellular cAMP content via beta3-adrenergic receptor, probably leading to the activation of PKA.
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Affiliation(s)
- T Suenaga
- Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Hiroshima, Japan
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Motoyashiki T, Miyake M, Yoshida A, Morita T, Ueki H. A vanadyl sulfate-bovine serum albumin complex stimulates the release of lipoprotein lipase activity from isolated rat fat pads through an increase in the cellular content of cAMP and myo-inositol 1,4,5-trisphosphate. Biol Pharm Bull 1999; 22:780-6. [PMID: 10480313 DOI: 10.1248/bpb.22.780] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A vanadyl sulfate-bovine serum albumin complex (vanadyl-BSA) prolonged the stability of the V4+ oxidation state, although vanadyl alone can readily change the oxidation state from V4+ to V5+ under physiological conditions. Vanadyl-BSA stimulated the release of lipoprotein lipase (LPL) activity from isolated rat fat pads and increased the cellular LPL activity in a time-dependent manner. These effects were independent of protein synthesis. Propranolol, quin 2-AM, ruthenium red, and neomycin all inhibited LPL release more potently than the increase in activity. In contrast, potent inhibition of the increase effect was observed with genistein and wortmannin. Short-term incubation of the fat pads with vanadyl-BSA showed a transient increase in the cellular content of cAMP and myo-inositol 1,4,5-trisphosphate (IP3), which was inhibited by propranolol and neomycin, respectively. These results suggest that vanadyl-BSA stimulates the release of LPL activity through an increase in the cellular content of cAMP and IP3, leading to an increased intracellular Ca2+ concentration, and that it also increases cellular LPL activity via process(es) sensitive to genistein and wortmannin.
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Affiliation(s)
- T Motoyashiki
- Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Hiroshima, Japan
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Motoyashiki T, Fukamachi M, Morita T, Shiomi H, Ueki H. Involvement of adenosine in vanadate-stimulated release of lipoprotein lipase activity. Biol Pharm Bull 1998; 21:889-92. [PMID: 9781834 DOI: 10.1248/bpb.21.889] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A short-term incubation of isolated rat fat pads with vanadate showed the stimulated release of lipoprotein lipase (LPL) activity and suppression of the rise in extracellular adenosine level. The addition of adenosine to the medium showed inhibition of both the stimulated release of LPL activity and an increase in intracellular cAMP content by vanadate. A progressive increase in 5'-nucleotidase activity in the particulate fraction containing plasma membrane was suppressed by vanadate in a time- and dose-dependent manner, suggesting that vanadate inhibits, in part, the production of adenosine based on a dephosphorylation of AMP. In adipocytes, the inhibition of adenylate cyclase via A1 adenosine receptor is more predominant than the stimulation of adenylate cyclase via A2 adenosine receptor (Londos C. et al., Proc. Natl. Acad. Sci. U.S.A., 75, 5362-5366 (1978)). Therefore, vanadate may stimulate the release of LPL activity from the fat pads by suppressing the rise in extracellular adenosine level, accompanied by the activation of adenylate cyclase activity.
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Affiliation(s)
- T Motoyashiki
- 1st Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Hiroshima, Japan
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Motoyashiki T, Miyake M, Morita T, Mizutani K, Masuda H, Ueki H. Enhancement of the vanadate-stimulated release of lipoprotein lipase activity by astilbin from the leaves of Engelhardtia chrysolepis. Biol Pharm Bull 1998; 21:517-9. [PMID: 9635510 DOI: 10.1248/bpb.21.517] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Astilbin, a dihydroflavonol rhamnoside isolated from the leaves of Engelhardtia chrysolepis, enhanced the vanadate-stimulated release of lipoprotein lipase (LPL) activity from rat isolated fat pads. N-[2-(Methyl-amino)ethyl]-5-isoquinolinesulfonamide (H-8), a potent inhibitor of cAMP-dependent protein kinase (PKA), markedly inhibited the enhancement by astilbin. Lipolysis in the fat pads was stimulated by astilbin alone in a dose-dependent manner and this stimulation was suppressed in the presence of vanadate, probably due to its antilipolytic action. A significant enhancement by astilbin was observed with increasing effects of vanadate on cAMP content in the fat pads and on cAMP phosphodiesterase (PDE) activity in the particulate fraction although astilbin alone showed only a slight increase in the cellular cAMP content and PDE activity. Astilbin may enhance the vanadate-stimulated release of LPL activity through a synergistic effect on an increase in the cellular cAMP content produced by vanadate accompanied by more potent activation of PKA.
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Affiliation(s)
- T Motoyashiki
- Department of 1st Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Hiroshima, Japan
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Ueki H, Mitsugi S, Kawashima Y, Motoyashiki T, Morita T. Orthovanadate stimulates cyclic guanosine monophosphate-inhibited cyclic adenosine monophosphate phosphodiesterase activity in isolated rat fat pads through activation of particulate myelin basic protein kinase by protein tyrosine kinase. Endocrinology 1997; 138:2784-9. [PMID: 9202218 DOI: 10.1210/endo.138.7.5224] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Involvement of protein kinases in the stimulation of cGMP-inhibited cAMP phosphodiesterase (PDE) activity by orthovanadate (vanadate) was studied. When the fat pads were incubated with 2 mM vanadate or 10 nM insulin, the stimulation of myelin basic protein kinase (MBPK) activity in the particulate by vanadate reached a maximum at 60 min. In contrast, insulin showed a transient increase at 20 min. A 60-min incubation of the fat pads with vanadate stimulated all activities of protein tyrosine kinase (PTK), MBPK, and PDE in the particulate, in a similar dose-dependent manner. Amiloride, a PTK inhibitor, inhibited the stimulations of three enzymes by vanadate in a similar concentration range. Enzyme fractions, which were separated from the solubilized particulate, were subjected to the immunoblot analysis. A fraction of MBPK was identified to contain a major protein of mol wt (44K) and a minor one (42K), both of which are immunoreactive with a mitogen-activated protein kinase (MAPK) antibody. The partially purified PDE activity was stimulated by the addition of the partially purified MBPK. The further stimulation was observed with the PTK-activated MBPK. These results suggest that vanadate stimulates in part the PDE activity through the activation of the particulate MBPK, probably MAPKs, by PTK sensitive to vanadate.
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Affiliation(s)
- H Ueki
- Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Hiroshima, Japan
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Motoyashiki T, Morita T, Ueki H. Involvement of the rapid increase in cAMP content in the vanadate-stimulated release of lipoprotein lipase activity from rat fat pads. Biol Pharm Bull 1996; 19:1412-6. [PMID: 8951155 DOI: 10.1248/bpb.19.1412] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Mechanisms of the stimulatory release of lipoprotein lipase (LPL) activity from isolated rat fat pads by sodium orthovanadate (vanadate) were studied through a cAMP-dependent process. A potent inhibitor of insulin receptor tyrosine kinase, quercetin, inhibited the vanadate-increasing effect on the LPL activity in fat pads, but did not inhibit the vanadate-stimulated release of LPL activity from the fat pads. Propranolol and N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide (H-8) decreased the vanadate-stimulated release in a dose-dependent manner. Isoproterenol and dibutyryl cAMP (Bt2cAMP) stimulated the release of LPL activity from fat pads. Vanadate, as well as isoproterenol, rapidly increased the cAMP content in fat pads, and this increase was almost completely inhibited by propranolol. Vanadate increased the cAMP-dependent protein kinase (PKA) activity ratios calculated from the measurement in the presence or absence of cAMP or PKa inhibitor. These results suggest that the vanadate-stimulated release of LPL activity is associated with a process involving a rapid increase in the cAMP content accompanied by the activation of PKA.
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Affiliation(s)
- T Motoyashiki
- First Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Hiroshima, Japan
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Ueki H, Yamasaki Y, Higo K, Motoyashiki T, Kawabata H, Morita T. Regulation of cyclic AMP phosphodiesterase activity by particulate protein tyrosine kinase and phosphotyrosine phosphatase activities sensitive to sodium orthovanadate. Biol Pharm Bull 1995; 18:214-8. [PMID: 7742786 DOI: 10.1248/bpb.18.214] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Sodium orthovanadate (vanadate) stimulated cAMP phosphodiesterase (PDE) and protein tyrosine kinase (PTK) activities and inhibited the phosphotyrosine phosphatase (PTPase) activity in the particulate of isolated rat fat pads. Okadaic acid never showed any increase in the PDE activity up to 1 microM. Amiloride inhibited in part both stimulations of PDE and PTK activities by vanadate. The particulate PTK activity had an optimal divalent ion requirement of 15 mM Mg+2+2 mM Mn+2 in the assay medium and was not inhibited by 1 mM N-ethylmaleimide, suggesting it to be a different type from the insulin receptor and cytosolic PTK activities. The PDE, PTK, and PTPase active fractions were separated from the solubilized particulate fraction on a DEAE-Sephacel column. PDE activity was increased by the addition of the PTK active fraction. A further increase was observed by using the PTK active fraction pretreated with 1 mM vanadate. In contrast, the addition of PTPase active fraction decreased the PDE activity. This decrease disappeared by using the PTPase active fraction pretreated with 1 mM vanadate. These results suggest that the PDE activity is in part regulated through a process involving the particulate PTK and PTPase activities sensitive to vanadate.
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Affiliation(s)
- H Ueki
- Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Hiroshima, Japan
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Ueki H, Ohkura Y, Motoyashiki T, Tominaga N, Morita T. Increase in lipoprotein lipase activity in isolated rat adipose tissue by selenate. Biol Pharm Bull 1993; 16:6-10. [PMID: 7690291 DOI: 10.1248/bpb.16.6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Sodium selenate (selenate), as well as insulin, increased the lipoprotein lipase (LPL) activity in isolated rat fat pads in a time- and dose-dependent manner. The increase effect of selenate was not additive to that of insulin. The action of selenate and insulin was decreased by amiloride and disappeared when Ca2+ was omitted from the incubation medium. Loading of a chelator of intracellular Ca2+ to the fat pads also greatly inhibited the action of selenate. The maximal increase in inositol 1,4,5-trisphosphate (IP3) content was observed with a 30-s incubation of the fat pads with selenate. Dibutyryl cyclic AMP, 3-isobutyl-1-methylxanthine, carbonyl cyanide m-chlorophenylhydrazone, tunicamycin, and monensin all inhibited the increase effect of selenate on the LPL activity to various extents. These results suggest that selenate increases the LPL activity via amiloride- and monensin-sensitive processes, involving the Ca2+ mobilization linked to a rapid increase in the IP3 content in fat pads.
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Affiliation(s)
- H Ueki
- Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Hiroshima, Japan
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Morita T, Motoyashiki T, Tsuruzono Y, Kanagawa A, Tominaga N, Ueki H. Rapid increase of inositol 1,4,5-trisphosphate content in isolated rat adipose tissue by vanadate. Chem Pharm Bull (Tokyo) 1992; 40:2242-4. [PMID: 1423792 DOI: 10.1248/cpb.40.2242] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- T Morita
- Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Japan
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