Apelin-13生物功能研究進(jìn)展

符 婉 田紹文游 詠

綜述

Apelin-13生物功能研究進(jìn)展

符 婉1田紹文2游 詠1

Apelin是由77個(gè)氨基酸構(gòu)成的多肽，其受體為血管緊張素樣G蛋白偶聯(lián)受體(APJ)。Apelin/APJ系統(tǒng)在外周與中樞均有廣泛分布；Apelin-13是Apelin亞型之一，具有較強(qiáng)的生物活性。本文綜述了Apelin-13參與心血管系統(tǒng)、呼吸系統(tǒng)、神經(jīng)系統(tǒng)、消化系統(tǒng)和內(nèi)分泌系統(tǒng)等生理病理過(guò)程調(diào)節(jié)的研究新進(jìn)展。

Apelin-13；心血管系統(tǒng)；呼吸系統(tǒng)；神經(jīng)系統(tǒng)；內(nèi)分泌系統(tǒng)

Tatemoto[1]于1998年首次從牛胃分泌物中提取出一種新的血管活性肽—Apelin。Apelin-血管緊張素樣受體（Apelin-angiotensin receptor-like，APJ）是O’Dowd于1993年首次發(fā)現(xiàn)的孤兒G白偶聯(lián)受體，Apelin是其內(nèi)源性配體。Apelin/APJ系統(tǒng)在外周與中樞均有廣泛分布。Apelin具有多個(gè)亞型：Apelin-12、Apelin-13、Apelin-17、Apelin-28和Apelin-36。Apelin-13作為Apelin亞型之一，具有較強(qiáng)的生物活性。[pGlu]Apelin-13是Apelin存在于心臟、大腦、下丘腦中的主要亞型，且具有多種生物學(xué)功能。本文綜述了Apelin-13參與心血管系統(tǒng)、呼吸系統(tǒng)、神經(jīng)系統(tǒng)、消化系統(tǒng)和內(nèi)分泌系統(tǒng)等生理病理過(guò)程調(diào)節(jié)的研究新進(jìn)展。

1 Apelin-13的生物學(xué)特性

1.1 Apelin-13的結(jié)構(gòu) 富含精氨酸和賴氨酸殘基的Apelin前體肽，被血管緊張素轉(zhuǎn)化酶2剪切成不同長(zhǎng)度的亞型，如Apelin-13、Apelin-17和Apelin-36。Apelin-13是C末端含有13個(gè)氨基酸的短肽[2]，見(jiàn)圖1。Apelin-13的N端參與調(diào)節(jié)其與APJ受體的結(jié)合，C端主要參與調(diào)控其生物活性。[pGlu]Apelin-13是Apelin-13的N端焦谷氨酸化形式，有較強(qiáng)的穩(wěn)定性，能夠防止C末端的多肽被酶分解。Kleinz等[3]進(jìn)一步研究顯示，Apelin-13生物活性較長(zhǎng)肽Apelin強(qiáng)，但其與受體結(jié)合能力較差。

Fig.1 Amino acid sequence of human Apelin subtypes圖1 人類Apelin亞型氨基酸序列

1.2 Apelin-13的分布 Apeilin-13分布廣泛，在人體大腦、心臟、胃、腎臟、視網(wǎng)膜、結(jié)腸、臍靜脈、脂肪組織、骨間質(zhì)祖細(xì)胞和血管內(nèi)皮細(xì)胞中都能檢測(cè)到Apelin-13的表達(dá)。有研究表明[pGlu]Apelin-13是健康人體血漿中存在的最主要的Apelin亞型，其血漿濃度為7.7～23.3 μg/L[4]。

2 Apelin-13的生物學(xué)功能

2.1 Apelin-13與心血管系統(tǒng) Apelin-13與APJ受體結(jié)合，能夠拮抗血管緊張素Ⅱ?qū)ρ艿氖湛s作用，從而舒張血管、降低血壓。一項(xiàng)針對(duì)中國(guó)沿海人群的流行病學(xué)調(diào)查顯示，血清Apelin-13水平與收縮壓、舒張壓和平均動(dòng)脈壓呈負(fù)相關(guān)[5]。研究顯示惡性高血壓與慢性腎病關(guān)系密切，慢性腎病患者中有非對(duì)稱性二甲基精氨酸（asymmetric dimethylarginine，ADMA）聚集，ADMA能夠造成血管內(nèi)皮損傷，引起惡性高血壓[6]。有研究顯示,ADMA呈劑量和時(shí)間依賴性地增加人臍靜脈血管內(nèi)皮細(xì)胞的通透性，Apelin-13可以通過(guò)ADMA損傷人臍靜脈內(nèi)皮細(xì)胞的屏障，直接引起人臍靜脈血管平滑肌細(xì)胞肌球蛋白輕鏈的增多[7]。動(dòng)物實(shí)驗(yàn)顯示，給予SD大鼠ADMA持續(xù)皮下泵入4周，與對(duì)照組比較，Apelin-13能夠顯著增加ADMA組大鼠的收縮壓，且機(jī)制是Apelin-13直接引起ADMA組大鼠血管平滑肌細(xì)胞肌球蛋白輕鏈的增 多[6]。此外，Apelin-13能夠通過(guò)激活磷脂酰肌醇-3激酶（phosphatidylinositol 3-kinase，PI3K）/蛋白激酶B（protein kinase B，AKT）信號(hào)通路促進(jìn)大鼠胸主動(dòng)脈血管平滑肌細(xì)胞增殖[8]。上述研究結(jié)果提示Apelin-13在不同條件下對(duì)血壓具有雙向調(diào)控作用。

Apelin-13亦具有抵抗缺血和缺血再灌注對(duì)心肌細(xì)胞損傷的作用。有研究顯示在大鼠左冠狀動(dòng)脈前降支梗死24 h后，連續(xù)5 d腹腔注射[pGlu]Apelin-13后，與對(duì)照組比較，Apelin-13能夠減少心肌梗死面積，增加心率和血清一氧化氮水平，抵抗缺血對(duì)心肌細(xì)胞的損傷[9]。在大鼠心肌缺血再灌注模型中，Aplein-13可拮抗缺血再灌注誘導(dǎo)的心肌細(xì)胞內(nèi)質(zhì)網(wǎng)應(yīng)激損傷[10-11]；而給予PI3K/AKT、胞外信號(hào)調(diào)節(jié)蛋白激酶1/2（ERK1/2）及一磷酸腺苷依賴的蛋白激酶（AMPK）等信號(hào)通路的抑制劑能夠阻斷Aplein-13拮抗內(nèi)質(zhì)網(wǎng)應(yīng)激誘導(dǎo)的細(xì)胞凋亡，提示Apelin-13對(duì)心肌細(xì)胞的保護(hù)作用需要PI3K/AKT、ERK及AMPK信號(hào)通路的參與[10-11]。

2.2 Apelin-13與呼吸系統(tǒng) 除草醚誘導(dǎo)的橫膈疝氣模型大鼠具有肺動(dòng)脈高壓癥，長(zhǎng)期肺動(dòng)脈高壓會(huì)導(dǎo)致肺血管平滑肌細(xì)胞增殖和遷徙。Hofmann等[12]發(fā)現(xiàn)該模型大鼠肺脈管系統(tǒng)中Apelin-13/APJ的mRNA表達(dá)水平顯著上調(diào)，提示Apelin-13信號(hào)可能與長(zhǎng)期肺動(dòng)脈高壓誘導(dǎo)肺血管平滑肌細(xì)胞增殖和遷徙有關(guān)。外源性給予Apelin-13能夠抑制低氧誘導(dǎo)的肺動(dòng)脈血管平滑肌細(xì)胞增殖、遷移和自噬[13]。此外，體外細(xì)胞實(shí)驗(yàn)發(fā)現(xiàn)肺腺癌細(xì)胞過(guò)表達(dá)APJ，Apelin-13可顯著增加腺癌細(xì)胞ERK1/2磷酸化水平，促進(jìn)肺腺癌細(xì)胞的增殖和自噬[14]。

2.3 Apelin-13與神經(jīng)系統(tǒng) Apelin-13在大腦中分布廣泛，在脊髓、腦橋/延髓、中腦、大腦皮質(zhì)、下丘腦、小腦、紋狀體、嗅球和海馬中均檢測(cè)到了Apelin-13 mRNA表達(dá)。研究表明Apelin-13具有保護(hù)神經(jīng)細(xì)胞損傷作用[15]。Zeng等[15]觀察到在無(wú)血清誘導(dǎo)大腦皮質(zhì)細(xì)胞損傷的實(shí)驗(yàn)中，Apelin-13可通過(guò)ERK1/2信號(hào)通路抑制門冬氨酸受體活化引起的Ca2+內(nèi)流、氧化應(yīng)激、線粒體功能損傷、細(xì)胞色素C的釋放及caspase-3的激活，保護(hù)大腦皮質(zhì)細(xì)胞凋亡和神經(jīng)興奮性毒性損傷。Khaksari等[16]發(fā)現(xiàn)，Apelin-13可以改善大腦中動(dòng)脈局部缺血引起的大鼠大腦再灌注損傷和病理性水腫，并顯著縮小腦梗死面積和水腫面積，其機(jī)制可能與Aplein-13抑制細(xì)胞凋亡過(guò)程有關(guān)。Apelin-13亦具有鎮(zhèn)痛作用。Lv等[17-18]發(fā)現(xiàn)在小鼠蛛網(wǎng)膜下腔注射醋酸誘導(dǎo)內(nèi)臟痛模型中，Apelin-13可發(fā)揮鎮(zhèn)痛樣作用，該效應(yīng)可被阿片類受體拮抗劑所阻斷。最近研究結(jié)果表明，Apelin-13可影響學(xué)習(xí)記憶和情緒。Telegdy等[19]研究發(fā)現(xiàn)Apelin-13能增強(qiáng)小鼠被動(dòng)回避學(xué)習(xí)記憶的鞏固過(guò)程，而α-腎上腺素能、類膽堿能、多巴胺能、5-羥色胺能、γ-氨基丁酸能等遞質(zhì)受體拮抗劑及一氧化氮合成抑制劑均能阻斷Apelin-13對(duì)記憶鞏固的增強(qiáng)作用。Telegdy等[20]研究顯示，在高架十字迷宮檢測(cè)實(shí)驗(yàn)中，Aplein-13能夠提高CFLP小鼠的抗焦慮水平，且給予酚芐明、氟哌啶醇、普萘洛爾（心得安）和二甲麥角新堿能夠阻斷Apelin-13的抗焦慮水平，提示Apelin-13的抗焦慮作用與α、β腎上腺素能、多巴胺能和5-羥色胺能有關(guān)。

2.4 Apelin-13與消化系統(tǒng) 早期研究發(fā)現(xiàn)APJ受體在胃腸道有分布，提示Apelin-13可能參與調(diào)控胃腸功能。Lv等[21]發(fā)現(xiàn)給予小鼠側(cè)腦室注射Apelin-13（3～10 μg/只）可抑制胃排空和胃腸道活動(dòng)，而腹腔注射Apelin-13（10～100 μg/只）對(duì)胃排空無(wú)影響。給予Apelin-13受體阻斷劑（F13A）和納洛酮可拮抗Apelin-13抑制胃排空的作用，提示APJ受體和阿片類受體參與了Apelin-13對(duì)胃排空的調(diào)控。此外，體外實(shí)驗(yàn)結(jié)果表明，給予結(jié)腸癌細(xì)胞APJ特異性受體拮抗劑F13A能顯著抑制結(jié)腸癌細(xì)胞的增殖[22]。

2.5 Apelin-13與內(nèi)分泌系統(tǒng) Aplein-13參與調(diào)控?cái)z食行為和能量穩(wěn)態(tài)。Sunter等[23]發(fā)現(xiàn)給予大鼠側(cè)腦室注射Aplein-13可以減少正常大鼠和禁食大鼠的食物攝取量；Taheri等[24]給予大鼠側(cè)腦室注射Apelin-13僅影響了禁食大鼠給藥后2～4 h的食物攝取量。Lv等[25]夜間給予小鼠側(cè)腦室注射Aplein-13后，可顯著降低給藥后4 h內(nèi)禁食小鼠和未禁食小鼠的攝食和攝水量，而白晝給予側(cè)腦室注射Aplein-13對(duì)未禁食小鼠的攝食和攝水量沒(méi)有影響。上述實(shí)驗(yàn)結(jié)果提示Apelin-13對(duì)攝食攝水行為的調(diào)控可能受多種因素的影響。Wattez等[26]研究顯示，在體內(nèi)和體外實(shí)驗(yàn)中，Apelin-13可呈劑量依賴性地促進(jìn)膽囊收縮素和胰高血糖素樣肽1的分泌，進(jìn)而調(diào)節(jié)攝食行為和糖穩(wěn)態(tài)。Shin等[27]發(fā)現(xiàn)在肥胖癥小鼠模型的脂肪組織及前體脂肪細(xì)胞中，Apelin-13是Apelin在脂肪組織中最主要的亞型。進(jìn)一步研究顯示，下丘腦室旁核微注射Apelin-13可引起下丘腦室旁核細(xì)胞中高表達(dá)C-fos，并且激活交感神經(jīng)刺激棕色脂肪細(xì)胞，使棕色脂肪細(xì)胞溫度升高，釋放能量[28]。

Apelin-13有利于治療糖尿病。Zeng等[29]發(fā)現(xiàn)Apelin-13對(duì)無(wú)血清誘導(dǎo)的間充質(zhì)干細(xì)胞損傷具有保護(hù)作用，骨髓間充質(zhì)干細(xì)胞移植可用于治療多種疾病，包括糖尿病。然而，99％的骨髓間充質(zhì)干細(xì)胞易在移植后24 h發(fā)生凋亡。改善低氧誘導(dǎo)間充質(zhì)干細(xì)胞損傷的促凋亡環(huán)境是治療損傷的關(guān)鍵。低氧會(huì)產(chǎn)生大量的活性氧代謝產(chǎn)物（reactive oxygen species，ROS）,ROS可以通過(guò)激活核因子活化B細(xì)胞κ輕鏈增強(qiáng)子(nuclear factor kappa-light-chain-enhancer of activated B cells,NF-κB)和ERK1/2通路誘導(dǎo)凋亡。因此，Apelin-13通過(guò)抑制ERK1/2通路和激活PI3K/AKT通路，抵抗ROS對(duì)骨髓間充質(zhì)細(xì)胞的損傷作用，從而用于治療糖尿病[30]。

3 小結(jié)與展望

Apelin-13信號(hào)系統(tǒng)廣泛分布于外周與中樞組織，參與多種生理病理過(guò)程的調(diào)節(jié)。而目前對(duì)Apelin-13信號(hào)系統(tǒng)功能的研究處于初始階段。在今后的研究中，一方面需要進(jìn)一步明確Apelin-13信號(hào)系統(tǒng)其他生物功能，并對(duì)其作用機(jī)制深入研究；另一方面，還需要將Apelin-13信號(hào)系統(tǒng)作為某種疾病治療靶點(diǎn)進(jìn)行針對(duì)性的臨床前研究。

[1]Tatemoto K.Search for an endogenous ligand of the orphan G protein-coupled receptor--discovery of Apelin,a novel biologically active peptide[J].Nihon Rinsho,2000,58(3):737-746.

[2]Kawamata Y,Habata Y,Fukusumi S,et al.Molecular properties of Apelin:tissue distribution and receptor binding[J].Biochim Biophys Acta,2001,1538(2-3):162-171.

[3]Kleinz MJ,Davenport AP.Emerging roles of Apelin in biology and medicine[J].Pharmacol Ther,2005,107(2):198-211.

[4]Zhen EY,Higgs RE,Gutierrez JA.Pyroglutamyl Apelin-13 identified as the major Apelin isoform in human plasma[J].Anal Biochem,2013,442(1):1-9.doi:10.1016/j.ab.2013.07.006.

[5]Zhu P,Huang F,Lin F,et al.Plasma Apelin levels,blood pressure and cardiovascular risk factors in a coastal Chinese population[J].Ann Med, 2013,45(7):494-498.doi:10.3109/07853890.2013.833767.

[6]Han X,Zhang DL,Yin DX,et al.Apelin-13 deteriorates hypertension in rats after damage of the vascular endothelium by ADMA[J]. Can J Physiol Pharmacol,2013,91(9):708-714.doi:10.1139/cjpp-2013-0046.

[7]Wang LY,Zhang DL,Zheng JF,et al.Apelin-13 passes through the ADMA-damaged endothelial barrier and acts on vascular smooth muscle cells[J].Peptides,2011,32(12):2436-2443.doi:10.1016/j. peptides.2011.10.001.

[8]Liu C,Su T,Li F,et al.PI3K/Akt signaling transduction pathway is involved in rat vascular smooth muscle cell proliferation induced by Apelin-13[J].Acta Biochim Biophys Sin(Shanghai),2010,42(6): 396-402.

[9]Li L,Zeng H,Chen JX.Apelin-13 increases myocardial progenitor cells and improves repair postmyocardial infarction[J].Am J Physiol Heart Circ Physiol,2012,303(5):H605-H618.doi:10.1152/ajpheart.00366.2012.

[10]Simpkin JC,Yellon DM,Davidson SM,et al.Apelin-13 and Apelin-36 exhibit direct cardioprotective activity against ischemia-reperfusion injury[J].Basic Res Cardiol,2007,102(6):518-528.

[11]Tao J,Zhu W,Li Y,et al.Apelin-13 protects the heart against ischemia-reperfusion injury through inhibition of ER-dependent apoptotic pathways in a time-dependent fashion[J].Am J Physiol Heart Circ Physiol,2011,301(4):H1471-H1486.doi:10.1152/ajpheart.00097.2011.

[12]Hofmann AD,Friedmacher F,Takahashi H,et al.Decreased Apelin and Apelin-receptor expression in the pulmonary vasculature of nitrofen-induced congenital diaphragmatic hernia[J].Pediatr Surg Int,2014,30(2):197-203.doi:10.1007/s00383-013-3450-1.

[13]Zhang H,Gong Y,Wang Z,et al.Apelin inhibits the proliferation and migration of rat PASMCs via the activation of PI3K/Akt/mTOR signal and the inhibition of autophagy under hypoxia[J].J Cell Mol Med,2014,18(3):542-553.doi:10.1111/jcmm.12208.

[14]Yang L,Su T,Lv D,et al.ERK1/2 mediates lung adenocarcinoma cell proliferation and autophagy induced by Apelin-13[J].Acta Biochim Biophys Sin(Shanghai),2014,46(2):100-111.doi:10.1093/ abbs/gmt140.

[15]Zeng XJ,Yu SP,Zhang L,et al.Neuroprotective effect of the endogenous neural peptide Apelin in cultured mouse cortical neurons[J]. Exp Cell Res,2010,316(11):1773-1783.doi:10.1016/j.yexcr.2010.02.005.

[16]Khaksari M,Aboutaleb N,Nasirinezhad F,et al.Apelin-13 protects the brain against ischemic reperfusion injury and cerebral edema in a transient model of focal cerebral ischemia[J].J Mol Neurosci, 2012,48(1):201-208.doi:10.1007/s12031-012-9808-3.

[17]Lv SY,Qin YJ,Wang NB,et al.Supraspinal antinociceptive effect of Apelin-13 in a mouse visceral pain model[J].Peptides,2012,37 (1):165-170.doi:10.1016/j.peptides.2012.06.007.

[18]Xu N,Wang H,Fan L,et al.Supraspinal administration of Apelin-13 induces antinociception via the opioid receptor in mice[J].Peptides,2009,30(6):1153-1157.doi:10.1016/j.peptides.2009.02.011.

[19]Telegdy G,Adamik A,Jaszberenyi M.Involvement of neurotransmitters in the action of Apelin-13 on passive avoidance learning in mice[J].Peptides,2013,39:171- 174.doi:10.1016/j.peptides.2012.10.011.

[20]Telegdy G,Jaszberenyi M.Transmitter mediation of the anxiolytic action of Apelin-13 in male mice[J].Behav Brain Res,2014,263: 198-202.doi:10.1016/j.bbr.2014.01.009.

[21]Lv SY,Yang YJ,Qin YJ,et al.Effect of centrally administered Apelin-13 on gastric emptying and gastrointestinal transit in mice[J]. Peptides, 2011, 32(5):978- 982. doi: 10.1016/j.peptides. 2011.01.023.

[22]Picault FX,Chaves-Almagro C,Projetti F,et al.Tumour co-expression of Apelin and its receptor is the basis of an autocrine loop involved in the growth of colon adenocarcinomas[J].Eur J Cancer, 2014,50(3):663-674.doi:10.1016/j.ejca.2013.11.017.

[23]Sunter D,Hewson AK,Dickson SL.Intracerebroventricular injection of Apelin-13 reduces food intake in the rat[J].Neurosci Lett, 2003,353(1):1-4.

[24]Taheri S,Murphy K,Cohen M,et al.The effects of centrally administered Apelin-13 on food intake,water intake and pituitary hormone release in rats[J].Biochem Biophys Res Commun,2002,291(5): 1208-1212.

[25]Lv SY,Yang YJ,Qin YJ,et al.Central Apelin-13 inhibits food intake via the CRF receptor in mice[J].Peptides,2012,33(1):132-138.doi:10.1016/j.peptides.2011.11.011.

[26]Wattez JS,Ravallec R,Cudennec B,et al.Apelin stimulates both cholecystokinin and glucagon-like peptide 1 secretions in vitro and in vivo in rodents[J].Peptides,2013,48:134-136.doi:10.1016/ j.peptides.2013.08.005.

[27]Shin K,Pandey A,Liu XQ,et al.Preferential Apelin-13 production by the proprotein convertase PCSK3 is implicated in obesity[J]. FEBS Open Bio,2013,3:328-333.doi:10.1016/j.fob.2013.08.001.

[28]Masaki T,Yasuda T,Yoshimatsu H.Apelin-13 microinjection into the paraventricular nucleus increased sympathetic nerve activity in-nervating brown adipose tissue in rats[J].Brain research bulletin, 2012,87(6):540-543.doi:10.1016/j.Brain Res Bull.2012.02.004.

[29]Zeng X,Yu SP,Taylor T,et al.Protective effect of Apelin on cultured rat bone marrow mesenchymal stem cells against apoptosis[J]. Stem Cell Res,2012,8(3):357-367.doi:10.1016/j.scr.2011.12.004.

[30]Mottaghi S,Larijani B,Sharifi AM.Apelin 13:A novel approach to enhance efficacy of hypoxic preconditioned mesenchymal stem cells for cell therapy of diabetes[J].Medical hypotheses,2012,79(6): 717-718.doi:10.1016/j.mehy.2012.08.007.

(2014-04-23收稿 2014-05-25修回)

（本文編輯 閆娟）

Current Research Progress of Apelin-13

FU Wan1,TIAN Shaowen2,YOU Yong1
1 Department of Neurology,First Affiliated Hospital,University of South China,Hengyang 421001,China;2 Department of Physiology,Medical School,University of South China

Apelin is a polypeptide consisting of 77 amino acids.Apelin receptors are found to be the angiotensinlike G protein coupled receptor(APJ).Apelin/APJ system is widely distributed in the peripheral and central nervous system. Apelin-13 is one of the subtypes of Apelin,which has strong biological activity.This study reviewed the new research progress of Apelin-13 on physiological and pathological processes involved in the cardiovascular system,respiratory system,nervous system,digestive system and endocrine system.

Apelin-13;cardiovascular system;respiratory system;central nervous system;endocrine system

R592

A

10.3969/j.issn.0253-9896.2014.11.026

國(guó)家自然科學(xué)基金資助項(xiàng)目（81171281、81300158）、省級(jí)科技計(jì)劃項(xiàng)目（2013FJ3133）

1南華大學(xué)附屬第一醫(yī)院神經(jīng)內(nèi)科（郵編421001）；2南華大學(xué)醫(yī)學(xué)院生理教研室