何葦 盧勝軍 李承浩 周京琳 蒙田 鄭謙 石冰
(1.口腔疾病研究國(guó)家重點(diǎn)實(shí)驗(yàn)室,四川大學(xué),四川 成都 610041;2.遵義醫(yī)學(xué)院附屬口腔醫(yī)院 口腔頜面外科, 貴州 遵義 563000;
3.四川大學(xué)華西口腔醫(yī)院 唇腭裂外科,四川 成都 610041)
地塞米松和維生素B12對(duì)小鼠胚胎腭突發(fā)育早期成纖維生長(zhǎng)因子10及其2b受體信號(hào)的影響
何葦1,2盧勝軍1,3李承浩1,3周京琳1蒙田1鄭謙1,3石冰1,3
(1.口腔疾病研究國(guó)家重點(diǎn)實(shí)驗(yàn)室,四川大學(xué),四川 成都 610041;2.遵義醫(yī)學(xué)院附屬口腔醫(yī)院 口腔頜面外科, 貴州 遵義 563000;
3.四川大學(xué)華西口腔醫(yī)院 唇腭裂外科,四川 成都 610041)
目的 觀察地塞米松和維生素B12作用后小鼠胚胎腭突成纖維生長(zhǎng)因子10(Fgf10)及成纖維生長(zhǎng)因子2b受體(Fgfr2b)信號(hào)的變化。方法 將孕鼠分為致畸組、拮抗組和對(duì)照組,各組孕鼠分別注射地塞米松、地塞米松和維生素B12、生理鹽水,胚胎12.5和13.5 d處死孕鼠并獲取胚胎腭突,采用免疫印跡和BrdU染色的方法檢測(cè)胚胎腭突Fgf10和Fgfr2b信號(hào)和間充質(zhì)細(xì)胞增殖的變化。結(jié)果 地塞米松作用后,小鼠胚胎腭突Fgf10和Fgfr2b表達(dá)顯著下調(diào),間充質(zhì)細(xì)胞增殖抑制;維生素B12拮抗后,雖然Fgf10和Fgfr2b表達(dá)仍然下調(diào),但間充質(zhì)細(xì)胞增殖恢復(fù)。結(jié)論 地塞米松和維生素B12影響小鼠胚胎腭突Fgf10和Fgfr2b表達(dá)和間充質(zhì)細(xì)胞增殖,但二者的變化并不協(xié)調(diào)一致。
胚胎腭突; 地塞米松; 維生素B12
成纖維生長(zhǎng)因子10(fibroblast growth factor 10,F(xiàn)gf10)及其受體(fibroblast growth factor receptor 2b,F(xiàn)gfr2b)在哺乳動(dòng)物繼發(fā)腭發(fā)育早期有重要作用:介導(dǎo)胚胎腭突上皮和間充質(zhì)之間的相互作用,調(diào)節(jié)細(xì)胞的遷移、增殖、分化和維持細(xì)胞生存。哺乳動(dòng)物的腭發(fā)育是一個(gè)連續(xù)的、多步驟的過(guò)程,在整個(gè)胚胎發(fā)育中為晚期事件,故發(fā)育過(guò)程易受到外界因素的干擾。本研究旨在探明外源性糖皮質(zhì)激素地塞米松(dexamethasone,DEX)和維生素B12(vitamin B12,VitB12)對(duì)哺乳動(dòng)物腭發(fā)育早期Fgf10和Fgfr2b信號(hào)的影響。
SPF級(jí)C57BL/6J小鼠購(gòu)自四川大學(xué)華西動(dòng)物實(shí)驗(yàn)中心,8~10周齡,體重均在20 g以上。C57BL/6J雌雄小鼠以2∶1比例合籠過(guò)夜,次日晨檢查雌鼠有陰道栓者,記為胚胎0 d(embryo,E0),并稱(chēng)重標(biāo)記。實(shí)驗(yàn)動(dòng)物分為對(duì)照組、致畸組和拮抗組,每組3只孕鼠,分別在E10~E12每天腹膜下注射生理鹽水(normal sodium,NS),每只0.1mL,6mg·kg-1DEX、DEX 6mg·kg-1和VitB1210mg·kg-1。3只孕鼠于E12.5和E13.5處死并收集胚胎腭突,處死前2 h腹腔注射BrdU 50mg·kg-1,檢測(cè)胚胎腭突細(xì)胞增殖。
生理鹽水(湖南科倫制藥有限公司),DEX(Sigma公司,美國(guó)),VitB12(Sigma公司,美國(guó)),Trizol(Invitrogen公司,美國(guó)),BCA蛋白定量試劑盒(Millpore公司,美國(guó)),兔抗鼠多克隆抗體Fgf10/ Fgfr2b/GAPDH(Santa Cruz公司,美國(guó))。
電泳儀和半干轉(zhuǎn)膜儀(Bio-RAD公司,美國(guó)),聚偏二氟乙烯(polyvinylidene difluoride,PVDF)膜(Millpore公司,美國(guó)),凝膠成像分析系統(tǒng)(Bio-RAD公司,美國(guó))。
分別于E12.5和E13.5斷頸處死孕鼠,取出胚胎后在體式顯微鏡剪取小鼠胚胎腭突,Trizol法提取總蛋白質(zhì)后,用BCA蛋白定量試劑盒檢測(cè)蛋白含量。配制10%/12%分離膠和5%濃縮膠,取含30μg小鼠胚胎腭突蛋白的細(xì)胞裂解上清液,加入5×SDS上樣緩沖液至終濃度為1倍,沸水中煮5min使蛋白變性,然后加入電泳膠電泳槽,濃縮膠80 V,電泳時(shí)間30min,分離膠100 V,電泳時(shí)間根據(jù)目的蛋白相對(duì)分子質(zhì)量大小以及蛋白標(biāo)志物指示調(diào)整。純甲醇活化孔徑為0.45μm PVDF膜1min,水洗30 s,取出電泳后的凝膠,然后將膠、濾紙和PVDF膜放入轉(zhuǎn)膜緩沖液中浸泡30min。在半干轉(zhuǎn)膜儀器中按濾紙-膜-凝膠-濾紙順序疊放,電壓25 V,轉(zhuǎn)膜時(shí)間根據(jù)目的蛋白相對(duì)分子質(zhì)量大小調(diào)整。轉(zhuǎn)膜完畢后取出PVDF膜,標(biāo)記后含5%脫脂奶粉TBST緩沖液封閉PVDF膜,37℃搖2 h后,加入適量適當(dāng)濃度的一抗,室溫孵育1 h后,4℃冰箱過(guò)夜,次日室溫下TBST洗3次;同上方法準(zhǔn)備二抗稀釋液并與膜接觸,室溫下孵育1~2 h后,室溫下TBST洗3次,將膜滴干后放在Bio-Rad凝膠成像系統(tǒng)的檢測(cè)儀板上,將等量混勻的A和B兩種試劑滴加于膜上,曝光并拍照。凝膠圖像分析:用凝膠圖像處理系統(tǒng)分析目標(biāo)帶的凈光密度值。
將標(biāo)本玻片放入68℃烤箱中烤片,然后常規(guī)二甲苯脫蠟和梯度乙醇依次脫水,3%H2O237℃孵育以阻斷滅活內(nèi)源性過(guò)氧化物酶,2mol·L-1HCl變性DNA,37℃孵育30min,0.125%胰蛋白酶室溫消化10min,正常羊血清工作液37℃封閉后滴加一抗(1∶400),37℃孵育2 h,室溫30 min,然后4℃過(guò)夜,次日滴加二抗37℃孵育30min,然后DAB顯色1~2min,自來(lái)水充分沖洗后,蘇木素復(fù)染30 s,常規(guī)脫水、透明、干燥和封片,光學(xué)顯微鏡下觀察拍照,并計(jì)數(shù)BrdU陽(yáng)性細(xì)胞。
數(shù)據(jù)統(tǒng)計(jì)分析用SPSS 13.0統(tǒng)計(jì)軟件包。所有結(jié)果用平均數(shù)±標(biāo)準(zhǔn)差表示,作t檢驗(yàn)和χ2分析,P<0.05表示差異有統(tǒng)計(jì)學(xué)意義。
免疫印跡分析結(jié)果見(jiàn)圖1和圖2。
圖1 E12.5和E13.5鼠胚胎腭突Fgf10和Fgfr2b免疫印跡Fig 1 Western blotting assay of Fgf10 and Fgfr2b of mouse embryonic palate at E12.5 and E13.5
圖2 對(duì)照組、致畸組和拮抗組小鼠胚胎腭突Fgf10和Fgfr2b的表達(dá)差異(*表示P<0.05)Fig 2 The expression difference of Fgf10 and Fgfr2b of mouse embryonic palate among control group,teratogenetic group and antagomistic group(*P<0.05)
從圖1和圖2可以看出:E12.5致畸組Fgf10在小鼠胚胎腭突的表達(dá)較對(duì)照組升高,但兩組間差異沒(méi)有統(tǒng)計(jì)學(xué)意義(P>0.05),而在拮抗組顯著降低(P<0.05);與對(duì)照組比較,致畸組Fgfr2b在小鼠胚胎腭突的表達(dá)顯著降低(P<0.05),在對(duì)照組和拮抗組間比較沒(méi)有顯著差異(P>0.05);E13.5時(shí),與對(duì)照組比較,F(xiàn)gf10的表達(dá)在致畸組和拮抗組降低,致畸組及拮抗組與對(duì)照組比較均有顯著性差異(P<0.05);Fgfr2b表達(dá)在致畸組和拮抗組均較對(duì)照組降低(P<0.05),而致畸組和拮抗組間比較沒(méi)有顯著差異(P>0.05)。
圖3表示小鼠胚胎腭突冠狀位切片BrdU染色計(jì)數(shù)細(xì)胞增殖,圖4表示E12.5和E13.5時(shí),對(duì)照組、致畸組和拮抗組小鼠胚胎腭突間充質(zhì)增殖細(xì)胞比較。圖3顯示E12.5對(duì)照組小鼠胚胎腭突檢測(cè)到較多BrdU(+)細(xì)胞,DEX干預(yù)后小鼠胚胎腭突的BrdU(+)細(xì)胞顯著下降(P<0.01,圖4),VitB12拮抗后BrdU(+)細(xì)胞沒(méi)有明顯增加。E13.5對(duì)照組、DEX和VitB12共干預(yù)組相比,DEX干預(yù)后小鼠胚胎腭突的BrdU(+)細(xì)胞顯著下降(P<0.01,圖4)。
圖4 E12.5和E13.5,對(duì)照組、致畸組和拮抗組小鼠胚胎腭突間充質(zhì)增殖細(xì)胞比較(*表示P<0.05)Fig 4 The difference of proliferation cells of mouse embryonic palatal mesenchyma among control group,teratogenetic group and antagomistic group at E12.5 and E13.5(*P<0.05)
哺乳動(dòng)物繼發(fā)腭的發(fā)育在整個(gè)胚胎發(fā)育過(guò)程中屬晚期事件,是一個(gè)多步驟連續(xù)的過(guò)程:胚胎腭突從兩側(cè)上頜突延伸,在舌兩側(cè)垂直生長(zhǎng),上抬于舌上方,在中線位置接觸、黏附和融合。這些因素導(dǎo)致腭發(fā)育非常易受外界環(huán)境和內(nèi)在遺傳因素的影響,如果其中任何一步受到干擾,都有可能使腭發(fā)育延遲導(dǎo)致腭裂的發(fā)生。在小鼠,繼發(fā)腭在E12.5從兩側(cè)上頜突延伸出來(lái),E13.5在舌兩側(cè)垂直位生長(zhǎng),接著E14.0上抬于舌之上,于E14.5在中線位置接觸,最后融合[2]。
DEX可使多個(gè)器官的重量減輕,如胸腺、脾、腎上腺、肝和肺等[3],并且能誘導(dǎo)包括唇腭裂和神經(jīng)管畸形在內(nèi)的多種實(shí)驗(yàn)室動(dòng)物畸形[4-5]。DEX干預(yù)孕期嚙齒動(dòng)物后,胚胎的腭板間充質(zhì)細(xì)胞增殖下降,腭板變小,上抬延遲,相對(duì)腭突無(wú)法在中線接觸,進(jìn)而影響其融合,形成腭裂[5]。
B族維生素,如葉酸、VitB6、VitB12等可降低實(shí)驗(yàn)動(dòng)物和人群唇腭裂的發(fā)生[6-7]。同時(shí)有研究[8-11]提示,B族維生素能降低藥物(可的松、苯妥英鈉、環(huán)磷酰胺等)誘導(dǎo)的實(shí)驗(yàn)動(dòng)物腭裂發(fā)生的風(fēng)險(xiǎn)。動(dòng)物實(shí)驗(yàn)[12]顯示,孕期大鼠血液和羊水中VitB12水平均降低,羊水中含量更低,孕期對(duì)維生素的需求較平時(shí)更大,說(shuō)明胎兒有可能因沒(méi)有充足的維生素而產(chǎn)生疾病,如神經(jīng)管畸形、面裂畸形等。而孕鼠注射DEX的同時(shí)給予不同質(zhì)量濃度的VitB12,胎鼠的腭裂發(fā)生率顯著降低[9]。筆者[13]先前的實(shí)驗(yàn)結(jié)果顯示,予孕鼠6mg·kg-1DEX后,胚胎腭裂發(fā)生率從3.1%升高至42.1%,而用VitB12拮抗后,胚胎腭裂發(fā)生率又顯著降低(42.1%~18.4%)。
DEX誘導(dǎo)的小鼠腭裂表型與Fgf10和Fgfr2b-/-小鼠腭裂表型相似[14-15]。Fgf10和Fgfr2b在繼發(fā)腭早期發(fā)育中有重要作用:表達(dá)于腭間充質(zhì)的Fgf10與表達(dá)于腭上皮的Fgfr2b結(jié)合,激活下游信號(hào)Shh和Bmp2表達(dá),進(jìn)而誘導(dǎo)間充質(zhì)細(xì)胞的增殖。擾亂Fgf10和Fgfr2b信號(hào)通路將影響上皮—間充質(zhì)間的相互作用,導(dǎo)致細(xì)胞增殖降低并影響上皮間充質(zhì)細(xì)胞的存活情況[14-15]。
本研究通過(guò)免疫印跡檢測(cè)DEX和VitB12干預(yù)后,E12.5和E13.5 Fgf10和Fgfr2b信號(hào)的變化,結(jié)果顯示Fgf10和Fgfr2b信號(hào)的變化并不完全一致。Fgf10和Fgfr2b主要調(diào)控間充質(zhì)細(xì)胞生存和增殖,F(xiàn)gf10-/-小鼠胚胎腭突間充質(zhì)增殖細(xì)胞數(shù)與野生型小鼠的無(wú)顯著差異,但凋亡細(xì)胞顯著增加,F(xiàn)gfr2b表達(dá)無(wú)變化,說(shuō)明Fgf10對(duì)細(xì)胞的增殖沒(méi)有直接影響,僅維持細(xì)胞的生存且不直接調(diào)控Fgfr2b的表達(dá)[15]。Spry2-/-小鼠胚胎腭突間充質(zhì)Fgfr2b表達(dá)增高,增殖細(xì)胞數(shù)增加[16],說(shuō)明Fgfr2b與細(xì)胞增殖密切相關(guān),并與Spry2的表達(dá)呈負(fù)相關(guān)關(guān)系。除此之外,胚胎腭突間充質(zhì)細(xì)胞增殖還受Msx1信號(hào)通路調(diào)控[17]。
E12.5 DEX作用后,對(duì)小鼠胚胎腭突Fgf10表達(dá)無(wú)顯著影響,DEX通過(guò)激活Spry2表達(dá)或抑制Msx1表達(dá)來(lái)降低Fgfr2b表達(dá),沒(méi)有足夠的Fgfr2b誘導(dǎo)下游信號(hào)因子Shh表達(dá),故細(xì)胞增殖受抑制。VitB12作用后Fgf10表達(dá)抑制,F(xiàn)gfr2b表達(dá)無(wú)顯著變化,VitB12通過(guò)抑制Spry2的表達(dá),從而使Fgfr2b表達(dá)受抑制程度減輕,但Shh的表達(dá)除受Fgfr2b調(diào)控外還受Msx1調(diào)控,VitB12可能對(duì)Msx1信號(hào)無(wú)影響,且Fgfr2b的表達(dá)恢復(fù)不足以補(bǔ)償Msx1的表達(dá)抑制,故細(xì)胞增殖抑制并未緩解。
E13.5 DEX干預(yù)母鼠后,胚胎腭突間充質(zhì)細(xì)胞Fgf10和Fgfr2b表達(dá)顯著降低,E11.5~E13.5 Fgf10表達(dá)在小鼠胚胎腭突[15],其表達(dá)降低可能是生理性的變化,而Fgfr2b表達(dá)貫穿于腭融合的全過(guò)程[1],此時(shí)仍受到DEX作用的影響,故表達(dá)仍受抑制,細(xì)胞增殖降低。VitB12作用后,小鼠胚胎腭突細(xì)胞增殖顯著恢復(fù),由于Spry2的表達(dá)由腭前部間充質(zhì)逐漸轉(zhuǎn)移到口腔面上皮,所以,VitB12雖然作用于Spry2,但對(duì)Fgfr2b的調(diào)控減弱,表達(dá)仍顯著降低。說(shuō)明Fgfr2b并不直接調(diào)控間充質(zhì)細(xì)胞增殖,而是通過(guò)Shh促進(jìn)增殖,而此時(shí)Shh上游除被調(diào)控外,尚受Msx1影響,其下游信號(hào)表達(dá)增強(qiáng),恢復(fù)細(xì)胞增殖。Fgf10表達(dá)同E12.5。
以上結(jié)果說(shuō)明DEX和VitB12可影響Fgf10和Fgfr2b的表達(dá)及小鼠胚胎腭突間充質(zhì)細(xì)胞的增殖,但是Fgf10和Fgfr2b并不直接調(diào)控細(xì)胞增殖,而是通過(guò)對(duì)下游信號(hào)因子如Shh的表達(dá)調(diào)控從而影響細(xì)胞增殖,但是DEX和VitB12作用廣泛,且腭發(fā)育過(guò)程受眾多信號(hào)調(diào)控,信號(hào)網(wǎng)絡(luò)間關(guān)系復(fù)雜,細(xì)胞增殖還受其信號(hào)因子調(diào)控,如Msx1、Bmp4和Bmp2,因此DEX和VitB12作用后的Fgfr2b和Fgf10表達(dá)變化與細(xì)胞增殖并不完全協(xié)調(diào)一致。因此,以后還需進(jìn)一步深入研究DEX和VitB12對(duì)小鼠胚胎腭突發(fā)育期間其他信號(hào)因子的影響。
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(本文編輯 湯亞玲)
Effects of dexamethasone and vitam in B12on expression of fibroblast grow th factor 10 and fibroblast grow th factor receptor 2b during early palatogenesis
HE Wei1,2,LU Sheng-jun1,3,LI Cheng-hao1,3,ZHOU Jing-lin1,MENG Tian1,ZHENG Qian1,3,SHI Bing1,3.(1.State Key Laboratory of Oral Diseases,Sichuan University,Chengdu610041,China;2.Dept.of Oral and Maxillofacial Surgery,The Affiliated Stomatological Hospital,Zunyi Medical College,Zunyi563000,China;3.Dept.of Cleft Lip and Palate Repair,West China Hospital of Stomatology,Sichuan University,Chengdu610041,China)
ObjectiveTo observe the alteration of fibroblast growth factor 10(Fgf10)and fibroblast growth factor receptor 2(Fgfr2b)signal in mouse embryonic palate after dexamethasone and vitamin B12exposure.MethodsDams were divided teratogenetic group,antagomistic group and control group and were respectively injected dexamethasone,dexamethasone and vitamin B12,and normal sodium.Dams were killed and fetus was collected at embryo 12.5 and 13.5 day.The expression of Fgf10 and Fgfr2b and mesenchymal cells proliferation of mouse embryonic by western blotting and BrdU assay were checked.Results Fgf10 and Fgfr2b expression was down-regulated and mesenchymal cells proliferation was inhibited significantly after dexamethasone exposure.After vitamin B12treatment,Fgf10 and Fgfr2b expression did not restore,but cells proliferation was recovered.ConclusionDexamethasone and vitamin B12affected the expression of Fgf10 and Fgfr2b of mouse embryonic palate and mesenchyme cells proliferation,but the change was disaccord.
embryonic palate; dexamethasone; vitamin B12
R 782.2
A
10.3969/j.issn.1000-1182.2010.05.025
1000-1182(2010)05-0551-05
2010-02-18;
2010-05-12
國(guó)家自然科學(xué)基金重點(diǎn)資助項(xiàng)目(30530730)
何葦(1977—),女,貴州人,住院醫(yī)師,博士
石冰,Tel:028-61153005