Recent Research News : Oxidative stress induces angiogenesis by activating TLR2 with novel endogenous ligands

배외식 생화학분자생물학회(구 한국생화학분자생물학회) 2011 생화학분자생물학회 소식 Vol.31 No.1

CCL2 recruits inflammatory monocytes to facilitate breast-tumor metastasis

배외식 생화학분자생물학회(구 한국생화학분자생물학회) 2011 생화학분자생물학회 소식 Vol.31 No.4

리간드 특이적인 G-단백질 결합 수용체의 활성화

배외식 한국생화학분자생물학회 2003 생화학분자생물학회 소식 Vol.23 No.3

Formyl peptide receptors in the mucosal immune system

정유선,배외식 생화학분자생물학회 2020 Experimental and molecular medicine Vol.52 No.-

Formyl peptide receptors (FPRs) belong to the G protein-coupled receptor (GPCR) family and are well known as chemotactic receptors and pattern recognition receptors (PRRs) that recognize bacterial and mitochondria-derived formylated peptides. FPRs are also known to detect a wide range of ligands, including host-derived peptides and lipids. FPRs are highly expressed not only in phagocytes such as neutrophils, monocytes, and macrophages but also in nonhematopoietic cells such as epithelial cells and endothelial cells. Mucosal surfaces, including the gastrointestinal tract, the respiratory tract, the oral cavity, the eye, and the reproductive tract, separate the external environment from the host system. In mucosal surfaces, the interaction between the microbiota and host cells needs to be strictly regulated to maintain homeostasis. By sharing the same FPRs, immune cells and epithelial cells may coordinate pathophysiological responses to various stimuli, including microbial molecules derived from the normal flora. Accumulating evidence shows that FPRs play important roles in maintaining mucosal homeostasis. In this review, we summarize the roles of FPRs at mucosal surfaces.

Phospholipase D is activated and phosphorylated by casein kinase-II in human U87 astroglioma cells

안봉현,민규식,배외식,배영석,민도식 생화학분자생물학회 2006 Experimental and molecular medicine Vol.38 No.1

Elevated expression of protein casein kinase II (CKII) stimulated basal phospholipase D (PLD) activity as well as PMA-induced PLD activation in human U87 astroglioma cells. Moreover, CKII-selective inhibi-tor, emodin and apigenin suppressed PMA-induced PLD activation in a dose-dependent manner as well as basal PLD activity, suggesting the involvement of CKII in the activation of both PLD1 and PLD2. CKII was associated with PLD1 and PLD2 in co-transfection experiments. Furthermore, CKII induced serine/thre -onine phosphorylation of PLD2 in vivo, and the multiple regions of PLD2 were phosphorylated by CKII in vitro kinase assay using glutathione S-trans -ferase- PLD2 fusion protein fragments. Elevated expression of CKII or PLD increased cell proliferation but pretreatment of cells with 1-butanol suppressed CKII-induced cell proliferation. These results sug -gest that CKII is involved in proliferation of U87 cells at least in part, through stimulation of PLD activity.

호중구의 자연 세포사멸 및 세포사멸 지연에 대한 Brefeldin A의 영향

김재석,이민정,이창민,이상화,배외식,곽종영 한국생명과학회 2002 생명과학회지 Vol.12 No.4

호중의 세포사멸은 자연적으로 일어나지만 여러 자극에 의한 신호에 의하여 증가하거나 지연된다. 본 연구에서는 세포 내 단백질 분비과정을 억제한다고 알려진 BFA가 호중구의 자연 세포사멸 및 세포사멸 지연에 어떠한 기작으로 작용하는가를 연구하였다. 호중구의 세포사멸은 사람 말초 혈액으로부터 분리하여 세포 배양 20시간 후 형태 변화, annexin V and propidium iodide의 염색, 및 DNA 전기영동 등으로 조사하였다. BFA는 농도 의존형으로 호중구의 세포사멸을 증가시킨다. CM-CSF나 LPS에 의한 세포사멸의 지연도 BFA에 의하여 억제되었다. 그러나 BFA의 영향은 db-cAMP, dexamethasone, 및 IL-8을 처리한 세포에서는 큰 영향을 받지 않았다. PKC-5의 억제제인 rottlerin에 의한 세포사멸의 지연은 BFA에 의하여 감소하였다. 그러나 BFA에 의한 세포사멸의 유도는 caspase-3 억제제인 zDEVD-fmk에 의하여는 영향을 받지 않았다. 한편, 세포사멸 억제에 관여하는 Mcl-1 단백질의 발현은 BFA의 처리에 의하여 감소하였다. 이들 결과들은 세포 내 단백질 분비 과정의 억제가 호중구의 세포사멸에 관여하며 이들의 작용은 Mcl-1 발현의 조절에 의한다는 것을 제시하고 있다. Neutrophil apoptosis is a constitutive process that can be enhanced or delayed by various stimuli. In this study, effect of brefeldin A (BFA), which affects biological process of secretion, on constitutive and delayed apoptosis of neutrophils was investigated. Neutrophil apoptosis was determined after culturing for 20 hr in vitro by morphological changes, annexin V staining and DNA electrophoresis. BFA increased the constitutive apoptotic rate of neutrophils in dose-dependent manner. The delay of apoptosis induced by granulocyte macrophage-colony stimulating factor and lipopolysaccharide was also blocked by 10 $\mu$M of BFA. However, this effect of BFA was less marked when neutrophils were treated with dexamethasone, interleukin-8, or dibutyryl-cAMP. Moreover, the delay of neutrophil apoptosis induced by rottlerin, a specific inhibitor of protein kinase C-$\delta$ was significantly abrogated by BFA. Although BFA-induced apoptosis was not blocked by the caspase-3 inhibitor, zDEVD-fmk, expression levels of myeloid cell leukemia-1 (Mcl-1) were down-regulated by BFA. These results suggest that derangement of vesicular protein transport may be involved in the apoptosis of neutrophils, and that the action of BFA on apoptosis is dependent on changes in the expression of Mcl-1.

Serum amyloid A inhibits dendritic cell differentiation by suppressing GM-CSF receptor expression and signaling

김지철,정영수,이하영,박준성,배외식 생화학분자생물학회 2017 Experimental and molecular medicine Vol.49 No.-

In this study, we report that an acute phase reactant, serum amyloid A (SAA), strongly inhibits dendritic cell differentiation induced by GM-CSF plus IL-4. SAA markedly decreased the expression of MHCII and CD11c. Moreover, SAA decreased cell surface GM-CSF receptor expression. SAA also decreased the expression of PU.1 and C/EBPα, which play roles in the expression of GM-CSF receptor. This inhibitory response by SAA is partly mediated by the well-known SAA receptors, Toll-like receptor 2 and formyl peptide receptor 2. Taken together, we suggest a novel insight into the inhibitory role of SAA in dendritic cell differentiation.

Phosphorylation of phospholipase D1 and the modulation of its interaction with RhoA by cAMP-dependent protein kinase

장민정,이민정,박해영,배외식,민도식,류성호,곽종영 생화학분자생물학회 2004 Experimental and molecular medicine Vol.36 No.2

Agents that elevate celular cAMP are known to inhibit the activation of phospholipase D (PLD). ylated by cAMP-dependent protein kinase (PKA) and PKA-mediated phosphorylation afects the in-teraction between PLD and RhoA, a membrane regulator of PLD. PLD1, but not PLD2 was found to be phosphorylated in vivo by the treatment of dibutyryl cAMP (dbcAMP) and in vitro by PKA. PKA inhibitor (KT5720) abolished the dbcAMP-in-duced phosphorylation of PLD1, but dibutyryl cGMP (dbcGMP) failed to phosphorylate PLD1. The association between PLD1 and Val14RhoA in an dbcAMP and dbcGMP. Moreover, RhoA but not PLD1 was disociated from the membrane to the cytosolic fraction in dbcAMP-treated cells. These results sugest that both PLD1 and RhoA are phosphorylated by PKA and the interaction bet-wen PLD1 and RhoA is inhibited by the phos-phorylation of RhoA rather than by the phosphor-ylation of PLD1.

호중구에서 phospholipase D의 활성에 대한 protein kinase G의 영향

박지연,이민정,장민정,이선영,배외식,곽종영 한국생명과학회 2003 생명과학회지 Vol.13 No.6

Phosphipase D(PLD)는 호중구의 활성에서 중요한 신호전달 인자로 작용한다. 본 연구에서는 호중구에서 PLD의 활성화에 대한 nitric oxide(NO)와 cGMP의 영향을 조사하였다. 세포 내 NO의 생성을 증가시키는 물질인 sodium nitroprusside (SNP)를 단독으로 처리하였을 때 SNP를 처리하지 않은 세포에 비교하여 PLD 활성은 0.5 mM 농도에서 2배 이상 증가하였다. 세포 내 cAMP의 농도를 증가시키는 물질인 dibutyryl-cAMP를 처리하였을 때 formyl-Met-Leu-Phe(fMLP)에 의한 PLD활성은 억제되었으나 cGMP를 증가시키는 물질인 8-bromo-cGMP(300 $\mu$M)를 단독으로나 fMLP와 같이 처리하였을 때 PLD의 활성은 큰 영향이 없었다. NO에 의한 PLD의 활성은 cGMP-의존형 인산화 효소인 protein kinase G(PKG)의 억제제인 KT 5823에 의하여 억제되지 않았는데 이러한 결과는 PKG 이외의 경로를 통하여 일어남을 제시한다. NO를 처리한 호중구에서 p38 mitogen activated protein kinase(MAPK)가 활성화되어 인산화된 p38 MAPK가 Western blot에서 증가되었다. NO에 의한 p38 MAPK의 인산화는 KT 5823에 의하여 억제되지 않았고 PLD 억제제인 n-butanol에 의하여도 영향을 받지 않았다. PLD 활성의 인자인 RhoA는 fMLP나 phorbol myristate acetate(PMA)의 자극에 의하여 세포질로부터 세포막으로 전이가 되었으나 cGMP의 전처리에 의하여 fMLP에 의한 RhoA의 전이는 억제되었으나 PMA에 의한 전이는 영향을 받지 않았다. 이들 결과들은 호중구 내 증가된 cGMP가 RhoA를 억제하였으나 세포 내 증가된 NO는 cGMP 이외의 인자를 통하여 PLD의 활성화를 일으킨다는 것을 제시하고 있다. Phospholipase D (PLD) plays an important role as a signaling molecule in the activation of neutrophils. In this study, effect of nitric oxide (NO) and cGMP on the activation of PLD in human neutrophils was investigated. Sodium nitroprusside (SNP), an agent to produce NO spontaneously in cells, alone increased PLD activity and the maximal activation was obtained with 0.5 mM SNP. Dibutyryl-cAMP, an agent to increase an intracellular cAMP concentration inhibited formyl-Met-Leu-Phe (fMLP)-stimulated PLD activity but 8-bromo-cGMP (300 $\mu$M), an agent to increase an intracellular cGMP concentration did not affect basal and fMLP-stimulated PLD activity. NO-induced activation of PLD was not blocked by KT 5823, an inhibitor of cGMP-dependent protein kinase (PKG), suggesting that NO-induced PLD activation is not mediated by cGMP. NO also stimulated p38 mitogen activated protein kinase (MAPK) in human neutrophils, indicated by increased phosphorylation of p38 MAPK in Western blotting. NO-induced phosphorylation of p38 MAPK was not inhibited by KT 5823 or n-butanol. RhoA, an regulatory factor of PLD activation was trans-located from cytosolic fraction to plasma membranes by fMLP or phorbol ester, and fMLP-stimulated but not phorbol ester-stimulated translocation of RhoA was inhibited by cGMP. These results suggest that NO stimulates PLD activity through other unidentified facto.(s) than cGMP even though cGMP inhibits the artivation of RhoA.

Serum amyloid A inhibits RANKL-induced osteoclast formation

오은서,이하영,김학중,박유정,서정곤,박준성,배외식 생화학분자생물학회 2015 Experimental and molecular medicine Vol.47 No.-

When mouse bone marrow-derived macrophages were stimulated with serum amyloid A (SAA), which is a major acute-phase protein, there was strong inhibition of osteoclast formation induced by the receptor activator of nuclear factor kappaB ligand. SAA not only markedly blocked the expression of several osteoclast-associated genes (TNF receptor-associated factor 6 and osteoclast-associated receptor) but also strongly induced the expression of negative regulators (MafB and interferon regulatory factor 8). Moreover, SAA decreased c-fms expression on the cell surface via shedding of the c-fms extracellular domain. SAA also restrained the fusion of osteoclast precursors by blocking intracellular ATP release. This inhibitory response of SAA is not mediated by the well-known SAA receptors (formyl peptide receptor 2, Toll-like receptor 2 (TLR2) or TLR4). These findings provide insight into a novel inhibitory role of SAA in osteoclastogenesis and suggest that SAA is an important endogenous modulator that regulates bone homeostasis.