• 대한의생명과학회지
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• 제12권2호
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• pp.113-118
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• 2006

Major pelvic ganglia (MPG) in rats are an unique autonomic ganglia, containing both sympathetic and parasympathetic neurons related with the function of bladder, penis and bowel. It has been widely known that ionotropic $GABA_A$ receptors are the molecular target of $\gamma$-aminobutric acid (GABA), a major inhibitory neurotransmitter in central nervous system. However, their functions and regulations of $GABA_A$ receptors expressed in autonomic ganglia have been poorly understood. 1 examined the modulatory role of adenylyl cyclase (AC) and protein kinase A(PKA) on $GABA_A$-induced inward currents in the neurons of rat MPG. $GABA_A$ receptors were identified using immunofluorescent labeling in the rat major pelvic ganglion. Electrophysiological experiments were performed to record the activities of $GABA_A$ receptors. $GABA_A$ receptors were expressed only in sympathetic neurons. GABA induced marked inward currents in a concentration-dependent manner. Mucimol ($5{\mu}M$), a $GABA_A$ receptor agonist induced inward currents were significantly reduced in the presence of SQ 225361 $20{\mu}M$, a AC inhibitor and myristoylated PKA inhibitor 100 nM. In addition, forskolin ($1{\mu}M$), AC activator, augmented the GABA induced currents. The activation of AC/PKA-dependent pathway could involve in the regulation $GABA_A$ receptors, expressed only in sympathetic neurons of rat MPG. These findings are helpful for the better understanding the function of various pelvic organs innervated by MPG.

• BMB Reports
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• 제45권12호
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• pp.724-729
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• 2012

In this study, we evaluated the anti-melanogenesis effects of Caffeoylserotonin (CaS) in B16 melanoma cells. Treatment with CaS reduced the melanin content and tyrosinase (TYR) activity in B16 melanoma cells in a dose-dependent manner. CaS inhibited the expression of melanogenesis-related proteins, including microphthalmia-associated transcription factor (MITF), TYR, and tyrosinase-related protein-1 (TRP-1), but not TRP-2. ${\alpha}$-MSH is known to interact with melanocortin 1 receptor (MC1R) thus activating adenylyl cyclase and increasing intracellular cyclic AMP (cAMP) levels. Furthermore, cAMP activates extracellular signal-regulated kinase 2 (ERK2) via phosphorylation, which phosphorylates MITF, thereby targeting the transcription factor to proteasomes for degradation. The CaS reduced intracellular cAMP levels to unstimulated levels and activated ERK phosphorylation within 30 min. The ERK inhibitor PD98059 abrogated the suppressive effect of CaS on ${\alpha}$-MSH-induced melanogenesis. Based on this study, the inhibitory effects of CaS on melanogenesis are derived from the downregulation of MITF signaling via the inhibition of intracellular cAMP levels, as well as acceleration of ERK activation.

• 대한의생명과학회지
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• 제27권3호
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• pp.170-176
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• 2021

Thapsigargin (TG), a sarco/endoplasmic reticulum (ER) Ca²⁺-ATPase (SERCA) inhibitor, has been widely used as an agonist for platelet aggregation for decades. In this study, we investigated the effect of TG on the release of lactate dehydrogenase (LDH) for platelets and elucidated its mechanism. Platelet LDH release and platelet aggregation were increased by TG treatment; 1,000 nM of TG induced the complete lysis of platelets. Other agonists such as collagen (2.5 ㎍/mL), thrombin (0.1 U/mL), and ADP (10 mM) did not induce significant platelet LDH release despite platelet aggregation. Finally, we investigated the effects of pharmacological inhibitors on TG-induced platelet aggregation and LDH release. SP600125, a JNK inhibitor, and LY294002, a PI-3K inhibitor, inhibited TG-induced platelet LDH release but not platelet aggregation. Forskolin, an adenylyl cyclase activator, also inhibited LDH release without affecting platelet aggregation by TG. These results suggest that the TG-induced platelet aggregation was accompanied by LDH release but regulated by a different signaling pathway.

• 생명과학회지
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• 제23권5호
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• pp.609-615
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• 2013

글리세올린 I은 다양한 피부 질환의 예방과 치료에 유용한 물질로 주목을 받아왔다. 그러나 피부 멜라닌 형성에 결정적 역할을 담당하는 포유류의 아데니닐 고리화 효소(이하 mAC)에 대한 직접적인 결합 형태와 상호 작용에 대한 연구는 현재까지 연구 보고된 사례가 없었다. 글리세올린 I 의 mAC 활성 부위에 대한 결합 작용 기작을 규명하기 위하여 우선 글리세올린 I과 SQ22,536 (mAC에 결합하여 mAC의 활성을 억제하는 것으로 이미 잘 알려진 단일 화합 물질)의 mAC에 대한 결합 친화도와 결합 형태를 비교 분석 하였다. 글리세올린 I은 mAC의 활성부위에 존재하는 Asp 1018, Trp 1020, Asn 1025와 각각 3개의 수소결합을 형성하는 것으로 분석되었고 SQ22,536은 mAC 활성부위의 Asp 1018, Asn 1025와 2개의 수소결합을 형성하여 글리세올린 I이 상대적으로 우월하게 결합하는 것으로 분석되었다. 글리세올린 I은 또한 포스콜린(forskolin)에 의해서 유도되는 세포내 멜라닌 형성 2차 신호전달 물질인 cyclic AMP의 생성과 이로인해 유발되는 단백질 인산화 효소 A의 인산화를 효과적으로 억제하는 것을 멜라노마 세포 실험을 통하여 확인하였다. 또한 글리세올린 I 을 장시간 세포에 투여하여도 세포의 생존률에는 영향을 주지 않음을 확인하였다. 본 연구 통하여 규명된 글리세올린 I의 mAC 활성 억제 효능 및 멜라닌 생성 신호전달 기작을 조절하는 성질을 이용하여 향후 흑색종과 같은 다양한 피부 질환 치료제 개발 및 미백화장품 핵심 물질 개발에 활용될 수 있을 것으로 사료된다.

• The Korean Journal of Physiology and Pharmacology
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• 제11권5호
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• pp.175-182
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• 2007

Members of prostaglandin(PG) E-series elicit cellular effects mainly through adenylyl cyclase-cAMP signaling. The role of $PGE_2$-induced increase in cAMP has been shown to be compartmentalized in the cardiac myocytes: $PGE_2$-induced increase of cAMP is not involved in the control of cardiomyocytic contraction. The purpose of the present study was to define the effect of $PGE_1$ on the cGMP levels and the role of $PGE_1$ in the atrial secretory function. Experiments were performed in perfused beating rabbit atria and atrial contractile responses, cGMP and cAMP efflux, and atrial natriuretic peptide(ANP) secretion were measured. $PGE_1$ increased cGMP as well as cAMP efflux concentration in a concentration-dependent manner, however, no significant changes in atrial secretory responses were observed(with $1.0{\mu}M\;PGE_1$; for cGMP, $144.76{\pm}37.5%$, n=11 versus $-16.81{\pm}4.76%$, n=6, control, p<0.01; for cAMP, $187.60{\pm}41.52%$, n=11 versus $7.38{\pm}19.44%$, n=6, control, p<0.01). $PGE_1$ decreased atrial dynamics slightly but transiently, whereas $PGE_2$ showed similar effects but with lower potency. Isoproterenol increased atrial cAMP efflux(with 2.0 nM; $145.71{\pm}41.89$, n=5 versus $7.38{\pm}19.44%$, n=6, control, p<0.05) and mechanical dynamics and decreased ANP secretion. The $PGE_1$-induced increase in cGMP efflux showed a bell-shaped concentration-response curve. $PGE_1$-induced increase of cGMP efflux was not observed in the presence of L-NAME, an inhibitor of nitric oxide(NO) synthase, or ODQ, an inhibitor of NO-sensitive guanylyl cyclase. L-NAME and ODQ showed no significant effect on the $PGE_1$-induced transient decrease of atrial dynamics. These data indicate that $PGE_1$ increases cGMP levels via NO-soluble GC signaling in the cardiac atrium and also show that $PGE_1$-induced increases in cGMP and cAMP levels are not involved in the regulation of atrial secretory and contractile functions.

• Molecules and Cells
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• 제23권1호
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• pp.23-29
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• 2007

Cyclic AMP-responsive element binding protein (CREB) is known to be associated with angiogenesis. In the present study we investigated the possible role of CREB in the expression of vascular endothelial growth factor (VEGF) by mouse macrophages. Over-expression of CREB increased VEGF secretion by cells of the RAW264.7 mouse macrophage cell line. It also increased the promoter activity of a mouse reporter driven by the VEGF promoter, while a dominant negative CREB (DN-CREB) abrogated the activity, suggesting that CREB mediates VEGF transcription. Forskolin, an adenylyl cyclase activator, stimulated VEGF transcription, and the PKA inhibitor H89 abolished this effect. IFN-${\gamma}$, a potent cytokine, stimulated VEGF expression only in part through the PKA-CREB pathway. These results indicate that PKA phosphorylates CREB and so induces VEGF gene expression. An analysis of mutant promoters revealed that one of the putative CREB responsive elements (CREs), at -399 ~ -388 in the promoter, is critical for CREB-mediated VEGF promoter activity, and the significance of this CRE was confirmed by chromatin immunoprecipitation assays.

• 대한한의학회지
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• 제21권4호
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• pp.193-203
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• 2000

Objectives : Hindered barrier function of vascular endothelium has been implicated in the initiation and progression of degenerative vascular diseases such as atherosclerosis. In this study, the effect of Sunghyangchungisan(SHCS) as a protectant against oxidant-induced destruction of endothelial barrier function was assessed. Methods : Toward this end, endothelial cells derived from the human umbilical vein were cultured as monolayers on permeable membrane filters. Endothelial permeability was monitored by measuring transendothelial electrical resistance and movement of low density lipoprotein (LDL) across the endothelial monolayer. Results : Along with increased movement of LDL, $H_2O_2$-induced increase in endothelial permeability was paralleled by a decrease in transendotheliaI electrical resistance. The effect of $H_2O_2$ was mimicked by phorbol 12-myristate 13-acetate (PMA), a potent activator of proteinkinase C. Calphostin-C, a protein kinase C inhibitor, effectively blocked the increase in endothelial permeability induced by $H_2O_2$ or PMA, indicating that activation of protein kinase C is associated with the $H_2O_2-induced$ permeability change. SHCS effectively protected the endothelial monolayer against $H_2O_2-induced$ increase in permeability, whereas, it did not affect PMA-induced change. Forskolin, a potent activator of adenylyl cyclase, antagonized $H_2O_2$ to increase endothelial permeability. In addition, in ${H_2O_2}-treated$ cens, intracenular cAMP concentration was significantly decreased, indicating that impaired cAMP production as well as activation of proteinkinase C is a mechanism underlying ${H_2O_2}>-induced$$H_2O_2$ with regard to its effect on intracellular cAMP content. However, SHCS itself did not affect resting cAMP concentration in endothelial cells. Conclusions : These results suggest that SHCS might operate as an effective protectant against oxidant-induced destruction of endothelial barrier function. The mechanism does not appear to involve direct interaction with protein kinase C- or cAMP-associated signaling mechanism.

• International Journal of Oral Biology
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• 제34권2호
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• pp.73-79
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• 2009

Cytosolic $Ca^{2+}$ is an important regulator of tumor cell proliferation and metastasis. Recently, the strategy of blocking receptors and channels specific to certain cancer cell types has emerged as a potentially viable future treatment. Oral squamous cell carcinoma is an aggressive form of cancer with a high metastasis rate but the receptor-mechanisms involved in $Ca^{2+}$ signaling in these tumors have not yet been elucidated. In our present study, we report that bradykinin induces $Ca^{2+}$ signaling and its modulation in the human oral squamous carcinoma cell line, HSC-3. Bradykinin was found to increase the cytosolic $Ca^{2+}$ levels in a concentration-dependent manner. This increase was inhibited by pretreatment with the phospholipase C-${\beta}$ inhibitor, U73122, and also by 2-aminoethoxydiphenyl borate, an inhibitor of the inositol 1,4,5-trisphosphate receptor. Pretreatment with extracellular ATP also inhibited the peak bradykinin-induced $Ca^{2+}$ rise. In contrast, the ATP-induced rise in cytosolic $Ca^{2+}$ was not affected by pretreatment with bradykinin. Pretreatment of the cells with either forskolin or phorbol 12-myristate 13-acetate (activators of adenylyl cyclase and protein kinase C, respectively) prior to bradykinin application accelerated the recovery of cytosolic $Ca^{2+}$ to baseline levels. These data suggest that bradykinin receptors are functional in $Ca^{2+}$ signaling in HSC-3 cells and may therefore represent a future target in treatment strategies for human oral squamous cell carcinoma.

• International Journal of Stem Cells
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• 제16권3호
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• pp.315-325
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• 2023

Background and Objectives: Glioblastoma (GBM) is an aggressive primary brain tumor characterized by its heterogeneity and high recurrence and lethality rates. Glioblastoma stem cells (GSCs) play a crucial role in therapy resistance and tumor recurrence. Therefore, targeting GSCs is a key objective in developing effective treatments for GBM. The role of Parathyroid hormone-related peptide (PTHrP) in GBM and its impact on GSCs remains unclear. This study aimed to investigate the effect of PTHrP on GSCs and its potential as a therapeutic target for GBM. Methods and Results: Using the Cancer Genome Atlas (TCGA) database, we found higher expression of PTHrP in GBM, which correlated inversely with survival. GSCs were established from three human GBM samples obtained after surgical resection. Exposure to recombinant human PTHrP protein (rPTHrP) at different concentrations significantly enhanced GSCs viability. Knockdown of PTHrP using target-specific siRNA (siPTHrP) inhibited tumorsphere formation and reduced the number of BrdU-positive cells. In an orthotopic xenograft mouse model, suppression of PTHrP expression led to significant inhibition of tumor growth. The addition of rPTHrP in the growth medium counteracted the antiproliferative effect of siPTHrP. Further investigation revealed that PTHrP increased cAMP concentration and activated the PKA signaling pathway. Treatment with forskolin, an adenylyl cyclase activator, nullified the antiproliferative effect of siPTHrP. Conclusions: Our findings demonstrate that PTHrP promotes the proliferation of patient-derived GSCs by activating the cAMP/PKA signaling pathway. These results uncover a novel role for PTHrP and suggest its potential as a therapeutic target for GBM treatment.

• 생명과학회지
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• 제27권2호
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• pp.149-154
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• 2017

미만성 거대 B 세포 림프종(DLBCL)은 비호지킨 림프종에서 가장 흔한 형태이다. DLBCL에서 약물치료에 대한 연구가 많은 진전을 보였지만, 아직 많은 환자의 경우 DLBCL로 인한 사망률이 상당하다. 따라서 DLBCL에 대한 이해와 새로운 표적 치료제의 개발이 필요하다. PDE (인산이에스테르 가수분해효소)4B는 최근 시행된 유전자 발현 프로파일링에서 약제내성을 가지는 DLBCL에서 과발현 되는 유전자로 밝혀졌다. PDE4B의 주된 역할은 이차전달자인 고리형 AMP (cylclic AMP, cAMP)를 5'AMP로의 가수분해를 촉진시켜 cAMP를 비활성화 시키는 것이다. cAMP는 B 세포에서 세포증식 저해와 세포사멸을 유도하고 PDE4B는 B 세포에서 이러한 cAMP의 기능을 소멸시키는 것으로 알려져 있다. 그러나 PDE4B의 과발현이 어떤 기작에 의한 것인지는 연구가 미비하다. 본 논문에서는 비정상적으로 발현된 마이크로 RNA (microRNA, miRNA)가 PDE4B의 과발현에 관련되어 있을 것이라는 가정하에 실험을 진행하였다. PDE4B 3'-UTR에는 세 개의 miR-23b 예상 결합부위가 존재하고, 이는 luciferase reporter assay를 통해서 확인하였다. 흥미롭게도, miR-23b 결합 부위들은 인간에서부터 도마뱀에 이르기까지 진화적으로 보존되어 있었고, 이는 세포 생리학적 측면에서 PDE4B-miR-23b 사이의 상호작용이 중요한 역할을 수행함을 암시하고 있다. miR-23b의 과발현은 PDE4B의 mRNA 발현을 감소시키고 세포내의 cAMP의 농도를 증가시켰다. 뿐만 아니라, miR-23b의 발현은 아데닐산고리화효소(adenylyl cyclase)의 활성약제인 forskolin이 처리된 경우에만 DLBCL 세포들의 증식과 생존을 억제하였다. 이는 miR-23b는 PDE4B 발현을 감소시킴으로써 세포증식과 생존을 조절함을 보여주는 것이다. 이를 통해 생각해 볼 때, miR-23b는 PDE4B를 억제함으로써 DLBCL에서 나타나는 항암제 내성을 극복할 수 있고, 따라서 miR-23b는 잠재적 종양 억제자로서 효과적인 치료적 타겟으로 예상된다.