• YAKHAK HOEJI
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• v.47 no.1
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• pp.31-36
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• 2003

To investigate the effect of protein kinase on melanin production via cAMP-dependent pathway, we measured the melanin amount and tyrosinase activity in B16 melanoma cells stimulated by alpha-melanocyte stimulating hormone (MSH), forskolin and 8-Br-cAMP. MSH, forskolin and 8-Br-cAMP significantly increased both melanin production and tyrosinase activity in B16 cells. Melanin production and tyrosinase activity by MSH are significantly inhibited by cyclic AMP-dependent protein kinase inhibitor (KT5720) and protein kinase C down-regulation treated with PMA. Bisindolmaleimide (1$\mu$M), protein kinase C inhibitor, significantly inhibited melanin production and tyrosinase activity stimulated by MSH, forskolin and 8-Br-cAMP with the following order of potency: MSH＞forskolin＞8-Br-cAMP. Tyrosine kinase inhibitor, genistein and DHC, significantly inhibited both, but the inhibitory effect was more potent in 8-Br-cAMP-stimulated B16 cells than MSH-stimulated cells. NFkB inhibitor (parthenolide) significantly inhibited melanin production and tyrosinase activity. Neither melanin production nor tyrosinase activity induced by MSH, forskolin and 8-Br-cAMP were affected by KN-62 (calmodulin-dependent protein kinase II inhibitor), PD098059 (mitogen-activated protein kinase inhibitor, MAPKK) and worthmannin (phosphatidylinositol 3-kinase inhibitor). These results suggest that both protein kinase C and tyrosine kinase are involved in melanin production by cyclic AMP-dependent pathway and NFkB pathway may play an important role in cyclic AMP-dependent melanin production in B16 melanoma cells.

• Animal cells and systems
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• v.9 no.3
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• pp.173-179
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• 2005

Cyclic-AMP-dependent protein kinase (PKA) seems to function as a negative regulator of the c-Jun $NH_2-terminal$ kinase (JNK) signaling pathway. We demonstrate here that the activity of the PKA catalytic subunit (PKAc) is reduced in apoptotic PC12 pheochromocytoma cells. Apoptotic progress was inhibited by dibutyryl cyclic AMP (dbcAMP), an analog of cAMP. The rescue by dbcAMP was attributable to inhibition of the JNK but not of the p38 signaling pathway, due to the induction of PKA activity. JNK was present in immunocomplexes of PKAc, and PKAc phosphorylated JNK in vitro. Presence of p38 kinase, however, was not prominent in immunocomplexes of PKAc. Our data suggest that JNK is a target point of negative regulation by PKAc in the JNK signaling pathway.

• The Korean Journal of Zoology
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• v.32 no.2
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• pp.153-162
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• 1989

Expedments were perfonned to examine the role of cAMP-dependent protein kinase (PK-A) and diacylglycerol-dependent protein kinase (PK-C) during the meiodc resumption and the first mitotic cell cycle of mouse embryogenesis. Mejoric GV oocytes and one-cell embryos derived from in vitro fertilization were cultured in vitro, and morphological changes in response to activators of PK-A and PK-C were examined. Treatments with a membrane-permeable cAMP analog, dbcAMP (0.1 mg/mi), phosphodiesterase inhibitor, IBMX (0.1 mM), biologically active phorbol ester, WA (10 nglmi), or a synthetic diacylglycerol, sn-diC8 inhibited resumption of melosis. Combination of PK-A and PK-C activator brought about furiher inhibition. On the contrary, dbcAMP (0.1 mg/mi), IBMX (0.2 mM), WA (10 nglml), and sn-diC8 (0.5 mM) did not inhibit pronucleus membrane breakdown (PNBD) when added S or G2 phase of cell cycle. However, activators of PK-C inhibited cleavage of one-cefl embryos. This result indicates that the action mechanism of PK-A and PK-C on dissolution of nuclear membrane in primary meiotic arrest oocytes may be different from that of mitotic one-cell embryos.

• The Korean Journal of Zoology
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• v.37 no.2
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• pp.222-231
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• 1994

밤바구미 유충기의 whole body로부터 cyclic AMP(CAMP)를 추출하여 농도 변화를 측정하였고 cyclic AMP-dependent protein kinase(PKA)를 부분 정제하여 활성도 변화를 조사하여 CAMP 농도와 PKA 활성도와의 소장관계를 비교하였다 CAMP 농도와 PKA 활성도는 HPLC와 liquid scintillation counter를 이용하여 측정하였다 CAMP 농도는 밤바구미 유충에서 월동전에 0.57 UMlg로 가장 높았고, 월동중에 0. 14 UMIS로 감소하였다가 월동후에 0.29 UMlg로 증가하였다 또한 PKA 활성도는 월동전에 2.56unit/mg로 가장 높았으며, 월동중에 0.62 unit/mg로 감소하다가 월동후에 07 unit/mg로 다시 증가하여 CAMP 농도 변화와 유사한 경향을 나타내었다. 이는 월동전에 휴면에 대비하여 최대의 취식으로 지방체 축적이 가장 많았고, 월동중에는 지방체의 소비가 증대되.기 때문에 감소하였다가, 월동후 휴면 종결과 유충-번데기 탈피를 준비하기 위해 'CAMP 농도와 PKA 활성도는 다시 증가하였다.

• The Korean Journal of Zoology
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• v.37 no.4
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• pp.565-572
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• 1994

연두금파리의 유충-번데기-성충의 발생에 따른 cyclic AMP(CAMP)와 ecdysteroids의 농도 및 cyclic AMP-dependent protein kinase(PKA)의 활성도를 High Performance Liquid Chromatography(HPLC)와 Liquid Scintillation Counter(LSC)를 이용하여 측정하고 상관 기능 변화를 조사하였다. CAMP의 농도와 PKA의 활성도는 종령유충 및 성충에서 낮은 갓(0.29 UM/g, 5.52~5.59 unit/mg)을 나타내었고 번데기 0일(0.49 UM/g. 92.22 unit/mg)과 7일(0.50UM/g, 24.45 unit/mg)에서 최고치를 보였으며 번데기 4일에서 최저수준(0.13 $\mu$M/g3.23 unit/mg)을 나타내었다. Ecdysone 농도는 번데기 2일에 최고치(37 84 USlg)를 4일에 최저치(18.46 Ugyg)를 보인 후, 5일에 24.37 1519로 상승하였으며 성충에서는 낮은 값을 나타내었다 그러나 20-hydroxvecdysone 농도는 번데기 4일(23.66 UgyS)과 번데기 6일(14.90 Ugyg)에 최고치를 이루었고, 7일에서 최저치(1.21 USi9)를 나타내었다.

• The Korean Journal of Zoology
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• v.38 no.2
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• pp.204-211
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• 1995

In an effort to develop a new therapeutic strategy for human gene therapy of solid ovarian tumor, we studied the expression of the p53 tumor suppressor Sene as well as regulatory subunits of cyclic AMP (cAMP)-dependent protein kinase in human ovarian carcinoma cells. Four cell lines (2774, Caov-3, SK-OV-3 and OVCAR-3) were selected for the analyses. The p53 transcript and protein were detected only in the 2774 cell line by Northern and Western Bnalysis. In the relatively fast growing cell line, SK-OV-3, the %rope 1 a regulstorv subunit (RIA of CAMP-dependent protein kinase was the highest among the four cell lines. The expression level of $RII\beta$ protein was low in the four cell lines examined. These results maw point to a direction to select the target gene(sl to be employed for gene therapy to control the ovarian cancer.

• The Korean Journal of Physiology
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• v.29 no.1
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• pp.39-50
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• 1995

This study was designed to clarify the action of cyclic nucleotides, cyclic AMP and cyclic GMP, on phorbol 12,13-dibutyrate (PDBu)-induced contraction in rings isolated from rabbit carotid artery. Arterial rings, 2 mm in width, were myographied isometrically in an isolated organ bath. PDBu produced slowly developing, sustained contraction in rabbit carotid artery, in a dose dependent manner, which was independent of extracellular $Ca^{2+}$ PDBu-induced contraction was relaxed by staurosporine, which suggests that PDBu-induced contraction is mediated by protein kinase C (PKC). $^{45}Ca^{2+}$ uptake by rabbit carotid artery was increased by PDBu during depolarization, but not in control. Isoproterenol and sodium nitroprusside (SNP) relaxed phenylephrine-induced contraction. However, SNP but not isoproterenol relaxed the contraction induced by PDBu. Acetylcholine relaxed PDBu-induced contraction in the presence of the endothelium. 8-bromo-cyclic AMP, a permeable analogue of cyclic AMP, suppressed phenylephrine-induced contraction but not PDBu-induced contraction. 8-bromo cyclic GMP relaxed both of them with dose dependency. A large dose of forskolin relaxed PDBu-induced contraction. PDBu increased cyclic AMP without considerable change in the level of cyclic GMP. Based on these findings, PDBu-induced contraction of rabbit carotid artery was relaxed by cyclic GMP more effectively than cyclic AMP, and the action of cyclic AMP could be mediated by cyclic GMP dependent protein kinase. Therefore it is suggested that the antagonistic action between protein kinase C and cyclic GMP-dependent protein kinase plays a major role in the regulation of vascular tone.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.1
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• pp.97-105
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• 1997

The regulatory role of cyclic nucleotides in the expression of neutrophil responses has been examined. fMLP-stimulated superoxide production in neutrophils was inhibited by dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP), histamine, adenosine + theophylline, cAMP elevating agents, and 8-bromoguanosine 3' ,5' -cyclic monophosphate (8-BrcGMP) and sodium nitroprusside, cGMP elevating agents. Staurosporine, a protein kinase C inhibitor, genistein, a protein tyrosine kinase inhibitor and chlorpromazine, a calmodulin inhibitor, inhibited superoxide production by fMLP, but they did not further affect the action of DBcAMP on the stimulatory action of fMLP. DBcAMP, histamine, adenosine+theophylline and genistein inhibited myeloperoxidease release evoked by fMLP, whereas BrcGMP, sodium nitroprusside and staurosporine did not affect it. The elevation of $[Ca^{2+}]_i$ evoked by fMLP was inhibited by genistein and chlorpromazine but was not affected by staurosporine. DBcAMP exerted little effect on the initial peak in $[Ca^{2+}]_i$ response to fMLP but effectively inhibited the sustained rise. On the other hand, BrcGMP significantly inhibited both phases. fMLP-induced $Mn^{2+}$ influx was inhibited by either DBcAMP or BrcGMP. These results suggest that fMLP-stimulated neutrophil responses may be regulated by cAMP more than cGMP. cAMP and cGMP appear not affect stimulated responses by direct protein kinase C activation. Their regulatory action on the stimulated neutrophil responses may be not influenced by other activation processes.

• Journal of Ginseng Research
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• v.21 no.3
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• pp.141-146
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• 1997

The role of cAMP in the differentiation process of F9 cells induced by ginsenosides was examined by performing transient transfixion assay with CRE-luciferase reporter plasmid, GR thansactivation assay with GRE-luciferase activity with or without treatment of CAMP and forskolin, an activator of adenylate cyclase, and protein klnase A assay in the presence of ginsenosides. Ginsenosides had no effect on CRE-transactivation activity, whereas retinoic acid induced the activity. When cAMP or forskolin was treated with ginsenosides, GRE-luciferase activity was further augumented by them. In addition, ginsenosides induced protein kinase A activity in the presence of cAMP. These results suggest that ginsenosides activate cAMP-dependent protein kinase A which, in turn, increase GR activity in F9 cells.

• Journal of Yeungnam Medical Science
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• v.29 no.2
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• pp.77-82
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• 2012

AMP-activated protein kinase (AMPK) is an important cellular fuel sensor. Its activation requires phosphorylation at Thr-172, which resides in the activation loop of the ${\alpha}1$ and ${\alpha}2$ subunits. Several AMPK upstream kinases are capable of phosphorylating AMPK at Thr-172, including LKB1 and CaMKK${\beta}$ ($Ca^{2+}$/calmodulin-dependent protein kinase kinase${\beta}$). AMPK has been implicated in the regulation of physiological signals, such as in the inhibition of cholesterol fatty acid, and protein synthesis, and enhancement of glucose uptake and blood flow. AMPK activation also exhibits several salutary effects on the vascular function and improves vascular abnormalities. AMPK is modulated by numerous hormones and cytokines that regulate the energy balance in the whole body. These hormone and cytokines include leptin, adiponectin, ghrelin, and even thyroid hormones. Moreover, AMPK is activated by several drugs and xenobiotics. Some of these are in being clinically used to treat type 2 diabetes (e.g., metformin and thiazolidinediones), hypertension (e.g., nifedipine and losartan), and impaired blood flow (e.g., aspirin, statins, and cilostazol). I reviewed the precise mechanisms of the AMPK activation pathway and AMPK-modulating drugs.