Tienthai P, Yokoo M, Kimura N, Heldin P, Sato E, Rodriguez-Martinez H
Department of Obstetrics and Gynaecology, Swedish University of Agricultural Sciences (SLU), SE-750 07 Uppsala, Sweden.
Reproduction. 2003 Jan;125(1):119-32.
Hyaluronan is related to essential reproductive processes in pigs. Hyaluronan produced by cumulus cells builds, via specific cell surface receptors, an extracellular matrix responsible for cumulus cell cloud expansion during final oocyte maturation, a preparatory event for ovulation and fertilization. In addition, hyaluronan that has been localized in the pig oviduct both in the intraluminal fluid and on the surface of the lining epithelium of the preovulatory sperm reservoir, has proven beneficial during in vitro fertilization and embryo culture, thus indicating that it has a role in vivo. This study monitored the immunolocalization, protein determination and gene expression of the major cell surface hyaluronan receptor CD44 in the epithelial lining of the pig oviduct during selected stages of standing oestrus, in relation to spontaneous ovulation. The CD44 immunostaining in the lining epithelium was localized to the surface membrane and the supranuclear domain of mainly the secretory cells, particularly in the sperm reservoir of both treatment (inseminated) and control (non-inseminated) specimens. Up to four hyaluronan-binding protein (HABP) bands (60, 90, 100 and 200 kDa) were detected in the tubal epithelium, and the 200 kDa band was determined as CD44 by immunoblotting. The expression of CD44 mRNA was higher before than after ovulation (P < 0.05), most conspicuously in the uterotubal junction (UTJ). In addition, CD44 expression in the preovulatory UTJ and the ampullary-isthmic junction (AIJ) of control animals was higher than in those that were inseminated (P < 0.05 and P < 0.01 for UTJ and AIJ, respectively). The results demonstrate for the first time that the specific hyaluronan receptor CD44 is expressed by the oviduct epithelial cells during spontaneous oestrus, and is particularly abundant in the sperm reservoir before ovulation. Presence of spermatozoa in this segment seemed to downregulate the receptor. The variation in the expression of CD44 in relation to spontaneous ovulation and the presence of spermatozoa indicate that the hyaluronan CD44-signalling pathway may play a role in oviduct function during sperm storage and fertilization in pigs.
透明质酸与猪的基本生殖过程相关。卵丘细胞产生的透明质酸通过特定的细胞表面受体构建细胞外基质，该基质负责在卵母细胞最终成熟过程中卵丘细胞云的扩展，这是排卵和受精的一个准备事件。此外，已证实位于猪输卵管管腔内液和排卵前精子储存库内衬上皮表面的透明质酸在体外受精和胚胎培养过程中有益，因此表明它在体内发挥作用。本研究监测了在静立发情选定阶段猪输卵管上皮中主要细胞表面透明质酸受体CD44的免疫定位、蛋白质测定和基因表达，与自发排卵相关。内衬上皮中的CD44免疫染色定位于主要是分泌细胞的表面膜和核上区域，特别是在处理（授精）和对照（未授精）标本的精子储存库中。在输卵管上皮中检测到多达四条透明质酸结合蛋白（HABP）带（60、90、100和200 kDa），通过免疫印迹法确定200 kDa带为CD44。排卵前CD44 mRNA的表达高于排卵后（P < 0.05），最明显的是在子宫输卵管连接处（UTJ）。此外，对照动物排卵前UTJ和壶腹峡部连接处（AIJ）的CD44表达高于授精动物（UTJ和AIJ分别为P < 0.05和P < 0.01）。结果首次证明，特定的透明质酸受体CD44在自发发情期间由输卵管上皮细胞表达，并且在排卵前的精子储存库中特别丰富。该段中精子的存在似乎下调了该受体。CD44表达与自发排卵和精子存在的变化表明，透明质酸CD44信号通路可能在猪精子储存和受精过程中输卵管功能中发挥作用。
