P2Y6受體生物學(xué)效應(yīng)的研究進(jìn)展

曾勇，文愛珍，王順民，劉丹，譚元生

(湖南中醫(yī)藥大學(xué)第一附屬醫(yī)院，長沙　410007)

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研究進(jìn)展

P2Y6受體生物學(xué)效應(yīng)的研究進(jìn)展

曾勇，文愛珍，王順民，劉丹，譚元生*

(湖南中醫(yī)藥大學(xué)第一附屬醫(yī)院，長沙410007)

【摘要】嘌呤受體分為P1和P2受體兩大類,其中，P2受體又分為配體門控離子通道型受體(P2X受體)和G蛋白偶聯(lián)型受體(P2Y受體)。P2Y6受體是P2Y家族中的一員，P2Y6受體參與心血管疾病、內(nèi)分泌疾病及神經(jīng)病變等疾病的發(fā)生。隨著氯吡格雷(P2Y12受體阻斷劑)等嘌呤受體阻斷劑被FDA批準(zhǔn)應(yīng)用于臨床，且表現(xiàn)出良好的療效，P2Y6受體的生物學(xué)效應(yīng)的研究，亦成為人們開展針對P2Y受體的新型靶向性藥物研究的熱點(diǎn)之一?；诜肿由飳W(xué)技術(shù)的發(fā)展，P2Y6受體生物學(xué)效應(yīng)的研究取得了顯著進(jìn)展。

【關(guān)鍵詞】P2Y6受體；生物學(xué)效應(yīng)；進(jìn)展

嘌呤受體分為P1和P2受體兩大類。其中，P2受體又分為配體門控離子通道型受體(P2X受體)和G蛋白偶聯(lián)型受體(P2Y受體)。P2Y6受體是P2Y家族中的一員，廣泛分布于機(jī)體各組織。P2Y6受體的內(nèi)源性配體是胞外核苷酸分子，主要包括：三磷酸腺苷(ATP)、二磷酸腺苷(ADP)、三磷酸尿苷(UTP)和二磷酸尿苷(UDP)及其衍生物。生理狀態(tài)下，胞外核苷酸分子的濃度維持在很低狀態(tài)，而胞內(nèi)濃度明顯高于胞外；病理狀態(tài)下，如缺氧、炎癥、損傷等，細(xì)胞可以通過自分泌、旁分泌或泄漏等形式，將胞內(nèi)的核苷酸釋放至細(xì)胞外激活P2Y6受體，產(chǎn)生生物學(xué)效應(yīng)。隨著氯吡格雷(P2Y12受體阻斷劑)等嘌呤受體阻斷劑成功被FDA批準(zhǔn)應(yīng)用于臨床，且表現(xiàn)出良好療效[1]。P2Y6受體生物學(xué)效應(yīng)的研究成為開展針對P2Y受體的新型靶向性藥物研究熱點(diǎn)。

1心血管系統(tǒng)

1.1促進(jìn)血管炎性病變發(fā)生

在TNF-a或LPS刺激下，血管內(nèi)皮細(xì)胞上P2Y6受體選擇性上調(diào)表達(dá)，而非其他P2Y或P2X受體，P2Y6受體激活NF-κB通路誘導(dǎo)白細(xì)胞介素-8(IL-8)和血管細(xì)胞粘附分子-1表達(dá)，促進(jìn)血管炎癥反應(yīng)發(fā)生[2]；同時，P2Y6受體能增強(qiáng)巨噬細(xì)胞促炎作用，促進(jìn)動脈粥樣硬化形成及動脈瘤等血管性疾病的形成[3]。

1.2介導(dǎo)VSMC收縮與增殖

早前Wang等[4]研究發(fā)現(xiàn)P2X1、P2Y2和P2Y6是血管平滑肌細(xì)胞(VSMC)表達(dá)最多的嘌呤受體，可能介導(dǎo)了平滑肌細(xì)胞的收縮及增殖。2008年，Bobbert等[5]研究表明通過激活P2Y受體，引起Ras-Raf-MEK-ERK1/2的級聯(lián)刺激，促進(jìn)VSMC的增殖。Govindan等[6]進(jìn)行了進(jìn)一步研究證實P2Y6是促進(jìn)VSMC收縮與增殖的受體之一。

1.3促進(jìn)心肌纖維化

壓力負(fù)荷(如高血壓)刺激心肌細(xì)胞，ATP、UDP等核苷酸經(jīng)Pnx離子通道釋放到胞外，刺激心肌細(xì)胞的P2Y6受體，通過偶聯(lián)的G12/13蛋白激活Rho途徑，調(diào)節(jié)纖維化因子的表達(dá)(如CTGF和TGF-β)，進(jìn)而促進(jìn)下游l/Ⅲ型膠原蛋白的表達(dá)，促進(jìn)心肌纖維化的產(chǎn)生[7]。

2調(diào)節(jié)小膠質(zhì)細(xì)胞功能

刺激小膠質(zhì)細(xì)胞P2Y6受體能顯著增強(qiáng)其對損傷神經(jīng)元細(xì)胞的吞噬作用[8]，抑制UDP/P2Y6信號通路則能阻止體內(nèi)外小神經(jīng)膠質(zhì)細(xì)胞的吞噬作用，有效阻止神經(jīng)元缺失和死亡[9]。經(jīng)LPS處理的混合培養(yǎng)的星形膠質(zhì)細(xì)胞和小神經(jīng)膠質(zhì)細(xì)胞中，UTP迅速轉(zhuǎn)變?yōu)閁DP激活P2Y6受體從而誘導(dǎo)小神經(jīng)膠質(zhì)細(xì)胞NO的釋放，NO通過控制星形膠質(zhì)細(xì)胞的增殖和阻止過度的聚集而致使其凋亡[10]。用UTP刺激原代培養(yǎng)的大鼠脊髓小膠質(zhì)細(xì)胞，UTP可通過刺激P2Y6受體通過磷脂酶C(PLC)介導(dǎo)的細(xì)胞外調(diào)節(jié)蛋白激酶(ERK)或p38蛋白磷酸化和隨后的NF-κB激活誘導(dǎo)大鼠脊髓小膠質(zhì)細(xì)胞產(chǎn)生MCP-1[11]。

脊髓P2Y6存在于脊髓小膠質(zhì)細(xì)胞，而P2Y11受體同時還存在于脊髓星形膠質(zhì)細(xì)胞，在脊髓神經(jīng)損傷大鼠體內(nèi)這兩種受體皆上調(diào)，脊髓P2Y6和P2Y11受體參與神經(jīng)性疼痛的維持[12]，而Syhr等[13]通過全身或鞘內(nèi)注射P2Y6受體的阻滯劑(MRS2578)，結(jié)果發(fā)行并未能影響到損傷所誘導(dǎo)的小鼠神經(jīng)性疼痛行為，因此認(rèn)為相比于其他嘌呤受體亞型，P2Y6受體嚴(yán)格意義上說未參與神經(jīng)損傷所誘導(dǎo)的神經(jīng)性疼痛的過程，并不支持上述觀點(diǎn)。

3呼吸系統(tǒng)

3.1促進(jìn)氣道炎癥發(fā)生及維持

在氣道上皮細(xì)胞，P2Y6誘導(dǎo)巨噬細(xì)胞炎性蛋白20(CCL20)趨化因子表達(dá)，并且這種作用能被P38抑制劑顯著性阻斷，因此認(rèn)為P2Y6受體通過激活絲裂原活化蛋白激酶(MAPK)/P38通路誘導(dǎo)CCL20的表達(dá)[13]，氣道炎癥反應(yīng)過程中，核苷酸釋放激活P2Y6受體，引起至少2種促炎因子的產(chǎn)生(IL-6和IL-8)，該過程是Ca2+依賴性的，而非cAMP/PKA通路。這種炎癥因子的分泌和“炎癥網(wǎng)絡(luò)”的形成在維持氣道炎癥性疾病中扮演者重要的角色[15]。

3.2促進(jìn)肺癌細(xì)胞損傷修復(fù)

研究發(fā)現(xiàn)[16]：人肺癌A549細(xì)胞上P2Y6受體呈高表達(dá)，而P2Y12受體表達(dá)非常弱，使用P2Y6受體阻斷劑(MRS2578)及基因敲除P2Y6受體的基因后，暴露于γ射線的腫瘤細(xì)胞生存率明顯下降，進(jìn)一步證實激活P2Y6受體后是通過ERK1/2通路而促進(jìn)暴露于γ射線的腫瘤細(xì)胞DNA損傷修復(fù)的。另外，激活氣道腔面上皮P2Y6受體能促進(jìn)電解質(zhì)的分泌運(yùn)輸[17]。

4促進(jìn)小腸炎癥發(fā)生及黏膜修復(fù)

小腸上皮細(xì)胞上調(diào)表達(dá)P2Y6受體，P2Y6受體通過活化ERK1/2調(diào)節(jié)IL-8分泌，進(jìn)而促進(jìn)中性粒細(xì)胞的遷移，促進(jìn)小腸炎癥反應(yīng)發(fā)生[18]。細(xì)胞損傷和UDP釋放使得P2Y6受體的表達(dá)增加，損傷誘導(dǎo)的UDP釋放，激活腸道上皮細(xì)胞P2Y6受體，介導(dǎo)TGF-β的從頭合成，為腸道黏膜修復(fù)發(fā)揮積極的補(bǔ)給作用[19]。

5調(diào)節(jié)膀胱功能

刺激膀胱平滑肌細(xì)胞P2Y6受體能通過PLC/IP3信號通路調(diào)節(jié)膀胱膀胱平滑肌的收縮[20]。在麻醉小鼠體內(nèi)，膀胱上皮細(xì)胞通過釋放ATP激活P2Y6受體能提高膀胱的排空頻率[21]，膀胱上皮細(xì)胞是通過泛連接蛋白-1管道釋放ATP激活P2Y6受體使膀胱收縮頻率增加[22]。

6抑制骨骼肌細(xì)胞凋亡

實驗證實TNF-α誘導(dǎo)小鼠骨骼肌細(xì)胞凋亡與NF-κB的活化相關(guān)[23]，激活P2Y6受體能降低TNF-a誘導(dǎo)的NF-κB提升作用而間接發(fā)揮抑制細(xì)胞凋亡的作用[24]。進(jìn)一步研究發(fā)現(xiàn)內(nèi)源性UDP和合成激動劑MRS2693濃度依賴性保護(hù)小鼠骨骼肌細(xì)胞細(xì)胞凋亡，P2Y6阻斷劑能阻止這種保護(hù)作用[25]。

7其他

另外，激活P2Y6受體能調(diào)節(jié)磷脂酶D的活性及磷脂酸生成，且阻斷磷脂酶D途徑后細(xì)胞能通過其他途徑促進(jìn)磷脂酸的生成[26]；用UDP激活P2Y6受體能有效保護(hù)小鼠感染水皰性口炎病毒[27]；P2Y6受體能調(diào)節(jié)白細(xì)胞對CCL2的反應(yīng)能力[28]；激活P2Y6能夠刺激胰島素的分泌[29]；以巨噬細(xì)胞為研究對象，P2Y6相對于其他P2Y嘌呤受體成員，在巨噬細(xì)胞中呈高表達(dá)，調(diào)控多種促炎癥因子如單核細(xì)胞趨化蛋白-1(MCP-1)、腫瘤壞死因子-a和炎性蛋白-1a/p等的轉(zhuǎn)錄表達(dá)，進(jìn)一步研究表明，P2Y6主要通過MEK1/2-ERK1/2MAPK～API信號通路從轉(zhuǎn)錄水平上調(diào)控MCP-1表達(dá)，而非P38、c-Jun氨基末端激酶或NF-κB通路[30]。

8結(jié)語

綜上所述，P2Y6受體的過度激活會引起嚴(yán)重的生理功能障礙和疾病，P2Y6受體參與心血管疾病、神經(jīng)病變、呼吸系統(tǒng)疾病及胃腸道疾病等的發(fā)生。其中，P2Y6受體介導(dǎo)細(xì)胞外核苷酸的活動，以參與心血管疾病的發(fā)生發(fā)展最為重要，體現(xiàn)在促進(jìn)血管炎癥反應(yīng)、增強(qiáng)血管張力、促進(jìn)平滑肌細(xì)胞的收縮與增殖等方面，因此尋找P2Y6受體阻斷劑的研究可能成為未來心血管疾病藥物研究領(lǐng)域的一大熱點(diǎn)。同時，P2Y6受體廣泛調(diào)控各種炎癥因子的表達(dá)及炎癥反應(yīng)，且與其他受體(CysLT1R和C5aR受體)協(xié)同調(diào)節(jié)炎癥因子的表達(dá)[31]，為開展抗炎癥藥物研究提供了新的靶點(diǎn)。此外，激活P2Y6受體能刺激胰島素的分泌，相應(yīng)受體的激動劑和拮抗劑具有開發(fā)成治療糖尿病藥物的前景。因此，研究P2Y6受體的生物學(xué)效應(yīng)具有重要的理論和應(yīng)用價值。未來關(guān)于P2Y6受體生物學(xué)效應(yīng)的研究應(yīng)傾向于在明確其生物學(xué)效應(yīng)后，對其生物學(xué)效應(yīng)進(jìn)行進(jìn)一步篩選，確證其在某一領(lǐng)域的實用價值。

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Research progress of the biological effect of P2Y6receptor

ZENG Yong，WEN Ai-zhen，WANG Shun-min, LIU Dan,TAN Yuan-sheng*

(the First Affiliated Hospital of Hunan University of TCM, Changsha 410007, China

【Abstract】Purine receptors are divided into P1 and P2 receptors. P2 receptors are divided into the ligand gated ion channel receptor (P2X receptor) and G protein coupled receptor (P2Y receptor). The P2Y6 receptor is a member of the P2Y family, P2Y6 receptors are involved in cardiovascular diseases, endocrine diseases and neuropathy diseases, etc. With clopidogrel (P2Y12receptor antagonist) and other purine receptor blocker approved by the FDA for clinical application, and showed good efficacy，study on biological effect of P2Y6 receptor also becomes one of the hot researches to new drug target for the P2Y receptor. Based on the development of molecular biological techniques, the research on biological effect of P2Y6 receptor achieved significant advances.

【Key words】P2Y receptors; Biological effect; Progress

[收稿日期]2015-09-06

Corresponding author:TAN Yuan-sheng, E-mail:tys702@126.com

Doi:10.3969/j.issn.1005-4847.2016.01.019

【中圖分類號】Q95-33

【文獻(xiàn)標(biāo)識碼】A

【文章編號】1005-4847(2016) 01-0107-04

[作者簡介]曾勇， 男，醫(yī)學(xué)碩士，醫(yī)師，從事心血管疾病的防治研究。E-mail: 781920555@qq.com[通訊作者]譚元生 男，醫(yī)學(xué)博士，主任醫(yī)師，教授，博士生導(dǎo)師，致力于心血管疾病的防治研究。E-mail: tys702@126.com

[基金項目]國家自然科學(xué)基金項目(項目編號：81473616)；湖南省科學(xué)技術(shù)廳科技計劃重點(diǎn)項目(項目編號：2013SK2025)；中醫(yī)內(nèi)科學(xué)省部共建教育部重點(diǎn)實驗室開放基金資助項目(ZYNK201507)；.湖南省中醫(yī)藥科研計劃重點(diǎn)項目(201534)。