畜牧兽医学报  2019, Vol. 50 Issue (9): 1802-1812. DOI: 10.11843/j.issn.0366-6964.2019.09.007    PDF    
牦牛p38MAPK在雌性主要生殖器官中的表达
韩小红, 何翃闳, 王靖雷, 张慧珠, 马悦, 马进彪, 赵生贤, 余四九, 崔燕, 樊江峰     
甘肃农业大学动物医学院, 兰州 730070
摘要:旨在研究p38MAPK在母牦牛主要生殖器官中的表达情况,了解其表达差异性,为牦牛的繁殖性能研究提供相关基础资料。本研究采集卵泡期、黄体期、妊娠期成年健康母牦牛(各2头)主要生殖器官样品,免疫组化技术检测p38MAPK蛋白的表达部位;qRT-PCR和Western-blot技术对其基因和蛋白进行相对表达量测定。结果:1)免疫组化结果显示,p38MAPK蛋白在牦牛的卵巢、输卵管和子宫均呈阳性表达;2)qRT-PCR结果表明,p38MAPK基因在卵巢中的表达量卵泡期显著高于妊娠期(P < 0.05);在输卵管中的表达量黄体期显著高于卵泡期和妊娠期(P < 0.05);在子宫中的表达量妊娠期极显著高于卵泡期和黄体期(P < 0.01);3)Western-blot结果显示,p38MAPK蛋白在卵巢中的表达量卵泡期极显著高于黄体期和妊娠期(P < 0.01);在输卵管中的表达量黄体期极显著高于卵泡期和妊娠期(P < 0.01);在子宫中的表达量妊娠期极显著高于卵泡期和黄体期(P < 0.01)。结果表明,p38MAPK在母牦牛同一生殖器官的不同繁殖阶段其表达存在差异性,其可能参与了牦牛卵泡发育、黄体功能发挥以及胚胎着床和发育等一系列生殖过程,为牦牛的繁殖性能研究提供相关基础资料。
关键词牦牛    p38丝裂原活化蛋白激酶    免疫蛋白印迹技术    实时荧光定量    
Expression of p38MAPK in the Main Reproductive Organs of Female Yaks (Bos grunniens)
HAN Xiaohong, HE Honghong, WANG Jinglei, ZHANG Huizhu, MA Yue, MA Jinbiao, ZHAO Shengxian, YU Sijiu, CUI Yan, FAN Jiangfeng     
College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China
Abstract: The aim of this study was to explore the expression of p38 mitogen-activated protein kinase (p38MAPK) protein and gene in the main reproductive organs of female yaks, accumulate some fundamental data for comprehending the role of p38MAPK in yak reproductive activity. The samples of main reproductive organs of adult healthy female yak during follicular phase, luteal phase and gestation period(2 each) were collected. Immunohistochemical method was used to locate the expression site of p38MAPK protein in the main reproductive organs of female yaks. The relative expression levels of the p38MAPK gene and protein were detected by qRT-PCR and Western-blot technique, respectively. The results showed that:1) The results of immunohistochemistry showed that p38MAPK protein was positively expressed in ovary, oviduct and uterus in female yak. 2) qRT-PCR results showed that the expression of p38MAPK gene in the ovary was significantly higher during follicular phase than that during gestation period(P < 0.05). The expression of p38MAPK gene in oviduct was significantly higher during the luteal phase than that during the follicular phase and gestation period (P < 0.05). The expression of p38MAPK gene in the uterus was significantly higher during gestation period than that during follicular phase and luteal phase (P < 0.01). 3) The results of Western-blot showed that the expression of p38MAPK protein in the ovary during the follicular phase was significantly higher than that during the luteal phase and gestation period (P < 0.01). The expression level of p38MAPK protein in the oviduct during the luteal phase was significantly higher than that during the follicular phase and gestation period (P < 0.01). The expression of p38MAPK protein in the uterus during gestation period was significantly higher than that during follicular phase and luteal phase (P < 0.01). In conclusion, these results suggest that p38MAPK may be involved in the regulation of reproductive processes that includes follicular development, luteal function and embryo implantation and embryo development. These data provide basic information for researching the reproductive mechanism of female yak.
Key words: yak     p38 mitogen-activated protein kinase     Western-blot technology     quantitative real-time PCR    

牦牛(Bos grunniens)是耐高寒、高海拔、低氧环境的特有物种,为高寒牧区最重要的生产生活资料[1-2],但实际生产中,母牦牛的繁殖性能很低[3-4]

p38MAPK是细胞内含有丝氨酸/苏氨酸的蛋白质激酶,其作为丝裂原活化蛋白激酶(mitogen-activated protein kinase, MAPK)家族的重要成员之一[5]。主要分布在哺乳动物的甲状腺、睾丸、胎盘、卵巢、肾上腺和垂体等组织[6-7],且在其繁殖过程中起着重要作用[8-9]。研究发现,低氧诱导因子-1(hypoxia-inducible factor-1, HIF-1)是重要的缺氧适应性调节因子,并且HIF系统异常会影响胚胎正常发育[10]。缺氧条件下,HIF-1α的激活依赖于磷脂酰肌醇-3激酶(phosphatidyl inositol 3-kinase,PI3K)和MAPK信号通路,但对MAPK的依赖有细胞和刺激选择性[11]。MAPK是生物体内重要的信号转导系统之一,其在哺乳动物体内的亚族还有细胞外信号调节激酶(extracellular regulated protein kinases, ERK)、c-Jun氨基末端激酶(c-Jun N-terminal kinase,JNK)和胞外信号调控激酶5(extracellular signalling kinase 5, ERK5)[12]。p38MAPK作为MAPK家族的一员,其激活途径遵循MAPK的激活途径:三级酶促级联反应,即包括上游激活蛋白、MAPK激酶的激酶(MAPKKK)、MAPK激酶(MAP-KK)、MAPK等4步[13]。p38MAPK发现于1993年,次年在小鼠肝细胞中成功克隆其基因,是由360个氨基酸组成大小为38 ku的蛋白[14-15]。研究表明,其存在p38α、p38β、p38γ、p38δ 4种亚型[16]。p38MAPK结构含有苏氨酸(threonine,T)和酪氨酸(tyrosine,Y)的双磷酸化位点,T、Y与其他氨基酸构成的三基肽结构称为“磷酸化唇”(phosphorylation lip)或“活化唇”(activation lip),它是激活p38MAPK的关键结构[17]。它对从紫外线到细胞因子的各种刺激都敏感且以磷酸化的方式激活,并以活化形式改变其他基因的表达水平,从而参与多种胞内信息传递过程,起到介导细胞生长、发育、分化及死亡等过程的作用[18]

前人研究表明,p38MAPK参与了多种哺乳动物生殖过程[19-21],但是否参与了母牦牛的生殖过程,迄今未见此方面的研究。本研究通过免疫组化、荧光定量PCR、免疫蛋白印迹技术等检测p38MAPK在母牦牛主要生殖器官的表达部位及相对表达量情况,确定其是否参与了母牦牛生殖过程,并为进一步探讨其在生殖过程中发挥作用的机制研究提供基础依据。

1 材料与方法 1.1 样品采集

在青海省西宁市乐家湾屠宰场选择无临床病理表现的成年母牦牛,待其颈动脉放血处死后迅速解剖剪取卵巢、输卵管和子宫组织样品(每个繁殖周期阶段各选2头),用无菌生理盐水冲洗干净,一部分用锡箔纸包裹并放入布袋中,迅速投入液氮中带回实验室,存于-80 ℃冰箱备用;另一部分用4%多聚甲醛固定后带回实验室,存于4 ℃冰箱中备用。

牦牛所处繁殖周期阶段的划分根据卵巢和子宫的发育状态综合判断。卵泡期:左右两侧卵巢上有且仅有1个10 mm以上卵泡、无肉眼可见黄体组织、两侧子宫角对称且不膨大;黄体期:左右两侧卵巢上至少有1个10 mm以上黄体、无8 mm以上卵泡、两侧子宫角对称且不膨大;妊娠期:左右两侧卵巢上至少有1个10 mm以上黄体、一侧子宫角明显膨大或子宫内有胎儿。

1.2 主要仪器和试剂

Total RNA Kit I(50)(OMEGA公司);Go ScriptTM Reverse Transcription System和GoTaq® Green Master Mix, 2×(Promega公司);SYBR® Premix Ex TaqTM EraserTM(Tli RNaseH Plus)(TaKaRa公司);阳离子防脱片(北京中杉金桥生物技术有限公司);DAB显色液、显/定影液、BeyoEcL Plus液(Beyotime公司);SP试剂盒(Bioss公司);β-actin (13E5) Rabbit mAb(Cell Signaling公司);p38MAPK(DBEl)XP® Rabbit mAb(Cell Signaling公司);Goat Anti-Rabbit IgG(Bioss公司);常规PCR仪(T100TMThermal Cycler,Rio-Rad公司),荧光定量PCR仪(ABI ViiA7,Life technologies公司);显微照相装置(DP71,Olympus公司)。

1.3 牦牛卵巢、输卵管和子宫的RNA提取及cDNA合成

RNA提取(Total RNA Kit I(50)的说明书):将-80 ℃备用的卵泡期、黄体期、妊娠期牦牛的卵巢、输卵管和子宫组织样研磨为粉末样,称0.1 g置于无RNase离心管中,并加入350 μL的组织裂解液后以14 000 r·min-1离心5 min,将上清液转移到新的无RNase离心管并加入70%乙醇,混匀。将其置于离心柱并以10 000 r·min-1离心1 min,弃滤液。依次用300 μL RNA Wash BufferⅠ和RNA Wash BufferⅡ室温10 000 r·min-1离心1 min,弃滤液,重复清洗2次。空离心柱以2000 r·min-1离心2 min,待其干燥后套入新的无RNase离心管,加入40 μL的DEPC水并10 000 r·min-1离心2 min,通过分光光度计测OD值(结果见表 1),并将无RNase离心管中的液体置于-80 ℃备用。

表 1 所提取RNA质量 Table 1 RNA quality extracted in this study

cDNA合成(Go ScriptTM Reverse Transcription System说明书):体系1(2 μL RNA样品、1.5 μL Primer Ioligo(di)、1.5 μL去离子水)于PCR扩增仪70 ℃反应5 min,冰上5 min。体系2(4 μL Go ScriptTM 5× Reaction Buffer、3 μL MgCl2、1 μL PCR Nucleotide Mix、0.5 μL Recombincmt RNasin Ribcnuclease Inbitor、1 μL Go Script Reverse Trauoriptase、5.5 μL去离子水)离心并涡旋后加入体系1中,PCR扩增:25 ℃ 5 min,42 ℃1 h,4 ℃∞,扩增产物-20 ℃保存。

1.4 p38MAPKβ-actin的引物设计

根据GenBank数据库中牛p38MAPK基因和牦牛β-actin基因的mRNA序列,通过primer-Blast设计引物(表 2),由华大基因科技有限公司合成引物。

表 2 引物序列 Table 2 Primer sequences
1.5 实时荧光定量PCR测定牦牛p38MAPK基因的表达

p38MAPKβ-actin基因在56 ℃退火温度下进行普通PCR扩增后,用2%琼脂糖凝胶电泳检测扩增产物,发现其扩增产物条带单一,并且大小与预期相符。实时荧光定量PCR(quantitative real-time PCR, qRT-PCR)反应体系(20 μL):SYBR® Premix Ex TaqTM EraserTM(2×)(10 μL)、ROX Reference Dye Ⅱ(50×)(0.4 μL)、模板cDNA(2 μL,400 ng·μL-1)、上下游引物(各0.8 μL,0.2 μmol·mL-1)、去离子水(6 μL)。RT-qPCR反应条件:95 ℃预变性4 min;40个循环(95 ℃变性30 s,56 ℃退火30 s,72 ℃延伸25 s)。繁殖期不同阶段的组织样均各做4次重复,进行熔解曲线检测,用2-ΔΔct法计算p38MAPK基因的相对表达量,并用SPSS 19.0软件分析其不同时期同一组织的表达差异性。

1.6 免疫组织化学法(IHC)检测牦牛p38MAPK蛋白的表达

采集组织样制作常规石蜡切片(4 μm),脱水至蜡,蒸馏水和PBS依次浸泡5 min。抗原修复:将切片置于柠檬酸盐缓冲液中,并在微波炉中进行抗原修复(高火加热至沸腾,转中火10 min),待其冷却至室温,PBS洗3次(每次3 min)。阻断:滴加3% H2O2溶液(SP试剂盒)覆盖组织,37 ℃作用10 min,PBS洗3次(每次3 min)。封闭:滴加封闭液(SP试剂盒A液)并于25 ℃作用15 min。孵育一抗:甩弃封闭液,滴加p38MAPK(DBEl)XP® Rabbit mAb工作液(一抗:PBS=1:300),4 ℃过夜(阴性对照组用PBS代替一抗工作液,此步骤之后,阳性与阴性对照组分开清洗),PBS洗3次(每次3 min)。二抗反应:滴加二抗工作液(SP试剂盒B液),37 ℃孵育15 min,PBS洗3次(每次3 min)。三抗反应:滴加三抗工作液(SP试剂盒C液),37 ℃孵育15 min,PBS洗3次(每次3 min)。DAB显色:滴加DAB显色液(1:50),显微镜下适度显色后, 自来水中终止显色10 min;蒸馏水浸泡5 min;苏木精复染30 s;盐酸酒精分化10 s;自来水适度反蓝;脱水透明;树脂封片并显微镜拍照。

1.7 免疫蛋白印迹法(Western-blot)检测牦牛p38MAPK蛋白的表达

将-80 ℃保存的卵泡期、黄体期、妊娠期牦牛的卵巢、输卵管和子宫组织样品研磨成粉末,称取0.1 g并加入裂解液(1 mL RIPA+10 μL PMSF),涡旋后在冰上裂解3 h,15 000 r·min-1离心5 min后吸取上清,蛋白于-80 ℃保存。测定蛋白浓度并将其稀释为同一浓度。蛋白变性:按蛋白样品:4×蛋白上样缓冲液=3:1的比例配置蛋白工作液,金属浴100 ℃变性10 min,冰上5 min后备用。Western-blot操作步骤:制作分离胶和浓缩胶并在70 V恒压下预电泳20 min;加样并将蛋白进行SDS-PAGE。制作三明治:负极-海绵-三层滤纸-SDS-PAGE分离胶-PVDF膜-三层滤纸-海绵-正极,利用半干法将蛋白转移到PVDF膜上;PBST洗30 min(5 min+10 min+15 min);5%脱脂奶粉封闭2 h,PBST洗3次,每次10 min。一抗孵育:含38 ku蛋白的PVDF膜置于p38MAPK(DBEl)XP® Rabbit mAb(5%脱脂奶粉=1:1 000)工作液,含42 ku蛋白的PVDF膜置于β-actin (13E5) Rabbit mAb(5%脱脂奶粉=1:1 000)工作液,两个PVDF膜4 ℃过夜(此后PVDF膜分开洗涤),PBST洗4次,每次10 min。二抗孵育:两个PVDF膜置于Goat Anti-Rabbit IgG mAb工作液(Goat Anti-Rabbit IgG mAb:5%脱脂奶粉=1:1 000)室温孵育2.5 h,PBST洗50 min(5 min+10 min+10 min+15 min+10 min);胶片曝光成影并扫描图片。利用Image Pro plus6.0收集灰度值并通过SPSS 19.0软件分析其差异性。

2 结果 2.1 牦牛p38MAPK的实时荧光定量PCR结果

p38MAPKβ-actin基因在56 ℃退火温度下进行普通PCR扩增后,用2%琼脂糖凝胶电泳检测发现,其扩增产物条带单一且大小与预期符合(图 1)。qRT-PCR方法检测p38MAPK基因在牦牛繁殖各阶段卵巢、输卵管、子宫的表达情况,其熔解曲线峰单一,故引物特异性能满足试验要求(图 2)。利用prism和SPSS 19.0对其进行统计学分析发现,在卵巢中,卵泡期p38MAPK基因的表达量显著高于妊娠期(P < 0.05);p38MAPK基因在输卵管的表达情况,黄体期的表达量显著高于卵泡期和妊娠期(P < 0.05),且卵泡期和妊娠期无显著性差异;p38MAPK基因在子宫的表达情况,妊娠期的表达量极显著高于卵泡期和黄体期(P < 0.01),卵泡期和黄体期子宫的表达量并没有显著性差异。即,p38MAPK基因在卵泡期卵巢、黄体期输卵管、妊娠期子宫表达量高于同组织的其他繁殖阶段,而且在妊娠期子宫的表达量最高(图 3)。

M. DNA相对分子质量标准;1.卵泡期卵巢;2.黄体期卵巢;3.妊娠期卵巢;4.卵泡期输卵管;5.黄体期输卵管;6.妊娠期输卵管;7.卵泡期子宫;8.黄体期子宫;9.妊娠期子宫 M. D750 DNA marker; 1. Ovary during follicular phase; 2. Ovary during luteal phase; 3. Ovary during gestation period; 4. Oviduct during follicular phase; 5. Oviduct during luteal phase; 6. Oviduct during gestation period; 7. Uterus during follicular phase; 8. Uterus during luteal phase; 9. Uterus during gestation period 图 1 p38MAPKβ-actin基因PCR扩增结果 Fig. 1 PCR amplification results for p38MAPK and β-actin genes
图 2 p38MAPKβ-actin的熔解曲线 Fig. 2 Melting curve of p38MAPK and β-actin genes
a. p38MAPK基因在各繁殖期输卵管的表达差异;b. p38MAPK基因在各繁殖期卵巢的表达差异;c. p38MAPK基因在各繁殖期子宫的表达差异。不同大写字母表示差异极显著(P < 0.01);不同小写字母表示差异显著(P < 0.05),图 6 a. Different expression of the p38MAPK gene in the oviduct during each breeding stages; b. Different expression of the p38MAPK gene in the ovary during each breeding stages; c. Different expression of the p38MAPK gene in the uterus during each breeding stages. The different uppercase letters indicate extremely significant difference (P < 0.01); the different lowercase letters indicate significant difference (P < 0.05), the same as figure 6 图 3 牦牛p38MAPK基因在繁殖期不同阶段主要生殖器官中的表达差异 Fig. 3 Differential expression of p38MAPK gene in main reproductive organs at different reproductive stages of yak
a.p38MAPK蛋白在各繁殖期输卵管的表达差异;b. p38MAPK蛋白在各繁殖期卵巢的表达差异;c. p38MAPK蛋白在各繁殖期子宫的表达差异 a.Different expression of the p38MAPK protein in the oviduct during each breeding stages; b. Different expression of the p38MAPK protein in the ovary during each breeding stages; c. Different expression of the p38MAPK protein in the uterus during each breeding stages 图 6 牦牛p38MAPK蛋白在繁殖期不同阶段主要生殖器官中的表达差异 Fig. 6 Differential expression of p38MAPK protein in main reproductive organs at different reproductive stages of yak
2.2 免疫组织化学方法对牦牛p38MAPK蛋白的定位

免疫组织化学试验结果发现,滴加过p38MAPK(DBEl)XP® Rabbit mAb工作液的各繁殖期牦牛的卵巢、输卵管和子宫组织切片均出现棕褐色区域,即为阳性表达,表明p38MAPK蛋白在各繁殖期牦牛的卵巢、输卵管和子宫均表达。p38MAPK在卵巢的表达:卵泡期和黄体期时,在颗粒层、卵泡膜内层、卵巢间质呈弥漫性分布且在卵巢动脉分布少,在妊娠时期主要分布在比较大的粒黄体细胞和卵巢动脉,膜黄体细胞见零星状分布(图 4A~C)。p38MAPK在输卵管的表达:卵泡期和黄体期主要分布于纤毛细胞、分泌细胞、次级皱襞的基细胞、肌层和浆液腺等,但妊娠时期仅分布于分泌细胞且染色较浅(图 4E~G)。p38MAPK在子宫的表达,在卵泡期主要分布于子宫肌层的平滑肌细胞,在子宫腺的腺上皮细胞和血管内皮细胞也少量分布;在黄体期时其仅在腺上皮细胞有轻微表达;在妊娠时期的表达最大,其在腺上皮细胞、肌层、血管及固有层均有强烈表达(图 4I~K)。滴加PBS工作液的阴性对照切片未见棕褐色阳性反应(图 4DHL)。

A.卵泡期卵巢; B.黄体期卵巢; C.妊娠期卵巢; D.卵巢阴性对照; E.卵泡期输卵管; F.黄体期输卵管; G.妊娠期输卵管; H.输卵管阴性对照; I.卵泡期子宫; J.黄体期子宫; K.妊娠期子宫; L.子宫阴性对照。LP.固有层; TM.肌层; EP.黏膜上皮; P.初级皱襞; S.次级皱襞; FA.卵泡腔; SG.颗粒层; TIF.卵泡膜内层; OA.卵巢动脉; UG.子宫腺; BV.血管; 黑色粗箭头.膜黄体细胞; 黑色细箭头.粒黄体细胞; 白色三角形.初级皱襞的基细胞; 黑色实心三角形.次级皱襞基细胞; 白色粗箭头.纤毛细胞; 白色细箭头.分泌细胞; 黑色空心三角形.腺上皮细胞; 黑色菱形.血管内皮细胞; 白色菱形.子宫平滑肌细胞; 黑色四角星.卵巢间质; 黑色五角星.浆液腺 A. Ovary during follicular phase; B. Ovary during luteal phase; C: Ovary during pregnancy phase; D. Ovarian negative control; E. Oviduct during follicular phase; F. Oviduct during luteal phase; G. Oviduct during pregnancy phase; H. Fallopian tube negative control; I. Uterus during follicular phase; J. Uterus during luteal phase; K. Uterus during pregnancy phase; L. Uterine negative control. LP. Lamina propria; TM. Muscle layer; EP. Mucosal epithelium; P. Primary wrinkles; S. Secondary wrinkles; FA. Follicular cavity; SG. Particle layer; TIF. Inner layer of the follicular membrane; OA. Ovarian artery; UG. Uterine gland; BV. Blood vessel; Black thick arrow. Membranous luteal cells; Black thin arrow. Granulosa cells; White triangle. Primary crease-based cells; Black solid triangle. Secondary wrinkle-based cells; White thick arrow. Ciliated cells; White thin arrow. Secreting cells; Black hollow triangle. Glandular epithelial cells; Black diamond. Vascular endothelial cells; White diamond. Uterine smooth muscle cells; Black four-pointed star. Ovarian stroma; Black five-pointed star. Serous gland 图 4 母牦牛主要生殖器官中p38MAPK蛋白的免疫组织化学染色 Fig. 4 Immunohistochemical staining of p38MAPK protein in the main reproductive organs of female yak
2.3 Western-blot检测牦牛p38MAPK蛋白的表达情况

Western-blot结果显示,p38MAPK蛋白在牦牛繁殖期各阶段的卵巢、输卵管、子宫中的分布存在量的差异;β-actin蛋白基本稳定分布于各繁殖期牦牛的卵巢、输卵管、子宫(图 5)。利用prism、Image Pro Plus6.0和SPSS 19.0对其进行统计学分析发现,p38MAPK蛋白在卵巢的表达情况,卵泡期的表达量极显著高于黄体期和妊娠期(P < 0.01);p38MAPK在输卵管的表达情况,黄体期的表达量极显著高于卵泡期和妊娠期(P < 0.01);p38MAPK在子宫的表达情况,妊娠期的表达量极显著高于卵泡期和黄体期(P < 0.01),卵泡期和黄体期子宫的表达量并没有显著性差异。即,p38MAPK蛋白在的卵泡期卵巢、黄体期输卵管、妊娠期子宫表达量高于同组织的其他繁殖阶段,而且在妊娠期子宫的表达量最高(图 6)。

1.卵泡期输卵管;2.妊娠期卵巢;3.黄体期输卵管;4.卵泡期卵巢;5.妊娠期输卵管;6.黄体期卵巢;7.卵泡期子宫;8.黄体期子宫;9.妊娠期子宫 1. Oviduct during follicular phase; 2. Ovary during gestation period; 3. Oviduct during luteal phase; 4. Ovary during follicular phase; 5. Oviduct during gestation period; 6. Ovary during luteal phase; 7. Uterus during follicular phase; 8. Uterus during luteal phase; 9. Uterus during gestation period 图 5 p38MAPK和β-actin蛋白的免疫蛋白印迹条带 Fig. 5 The Western-blot bands of p38MAPK and β-actin proteins
3 讨论

p38 MAPK作为MAPK家族成员之一,在雌性生殖方面起着极为重要的作用[22]。下丘脑、垂体和性腺轴严格调控着哺乳动物的生殖周期,其中促性腺激素释放激素对MAPK活性的调控是正常生育所必需的[23-24]。本研究也表明,p38MAPK在母牦牛繁殖期的不同阶段存在差异性分布,其可能也参与了母牦牛的生殖。

近年来,p38MAPK信号通路在胚胎发育和植入过程中受到广泛关注,发现p38MAPK对小鼠胚胎早期发育有很大影响,其通过小鼠植入前间隔来支持胚胎发育,而且抑制p38MAPK会抑制胚泡植入和胚胎的发育[25]。前人对p38MAPK在生殖器官的作用机制有很深入的研究,在卵巢方面,p38MAPK对卵泡发育可能有重要作用,不仅可促进小鼠卵母细胞的成熟,而且在大鼠的不同卵泡卵母细胞和不同鼠龄的颗粒细胞中出现持续稳定表达[26]。本试验结果也发现,p38MAPK在卵巢颗粒层、卵泡内膜层、卵巢基质以及妊娠后的粒黄体细胞等处强烈表达,且其在卵泡期的表达极显著的高于其他两个时期,推测p38MAPK对牦牛卵母细胞的发育成熟有一定的作用。在输卵管方面,输卵管上皮在卵巢排卵后,其纤毛细胞变高且纤毛增多;分泌细胞分泌功能更加旺盛,从而顺利将卵子运送到子宫,此后此现象逐渐减弱[27]。本试验结果显示,p38MAPK在繁殖期各阶段输卵管的纤毛细胞、分泌细胞、次级皱襞的基细胞等均有表达,其在黄体期输卵管的表达量明显高于卵泡期,且妊娠时期仅有分泌细胞残存微量表达,其表达情况与输卵管上皮层细胞的变化大致相符。也有学者发现,绵羊输卵管上皮细胞p38MAPK激活后对输卵管起到一定的保护作用[28],可大胆猜测p38MAPK在纤毛摆动运送卵子的过程中可能发挥了重要作用。在子宫方面,p38MAPK在人和小鼠体内主要分布于子宫蜕膜细胞和子宫平滑肌细胞,参与子宫内膜蜕膜化与分娩时子宫平滑肌的收缩等过程[29-30]。研究发现,其在绵羊胚胎和胎盘发育分化过程中也发挥重要作用,其通路异常会影响绵羊的受孕发育[31]。本研究发现,p38MAPK在妊娠期子宫的表达量极显著高于其他繁殖期子宫,且在子宫腺、肌层和固有层均有强烈表达,其可能与牦牛胎盘的形成过程、子宫腺分泌雌激素、分娩时子宫平滑肌的收缩等有关。

p38MAPK的磷酸化现象存在于大多数哺乳动物的整个妊娠阶段,且随着妊娠的进展这种现象逐渐加强[32-33],特异性的阻断p38MAPK通路会明显阻断着床和胚胎发育[34]。综上所述,p38MAPK在雌性生殖方面有着重要作用,所以本研究以母牦牛为研究材料,对p38MAPK在主要的生殖器官的表达进行研究,为牦牛的繁殖性能研究提供相关基础资料。研究发现,p38MAPK在卵泡期卵巢、黄体期输卵管、妊娠期子宫表达量高于同组织的其他繁殖阶段,这表明p38MAPK可能参与了牦牛卵泡发育、黄体功能发挥以及胚胎着床和发育等生殖过程。

4 结论

p38MAPK在母牦牛繁殖期不同阶段的同一生殖器官的中均表达,且各存在差异性。提示,p38MAPK可能参与了牦牛卵泡发育、黄体功能发挥以及胚胎着床和发育等一系列生殖过程,但到底通过怎样的途径,怎样的机制参与这些生殖生理过程,还需进行进一步的研究。此试验结果为牦牛的繁殖性能研究提供相关基础资料。

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