Uterine fibroblast growth factor-2 and embryonic fibroblast growth factor receptor-1 at the beginning of gastrulation in the rabbit

Molecular cloning and expression of FGF2 gene in pre-implantation developmental stages of in vitro-produced sheep embryos

Early embryonic mortality is one of the main sources of reproductive loss in domestic ruminants including sheep. Fibroblast growth factor-2 (FGF-2) is a member of FGFs family that mediates trophoblast activities and regulates embryonic development in various species. In this study, we have cloned, characterized sheep FGF2 cDNA (KU316368) and studied the expression in sheep embryos. Ovaries of non-pregnant sheep were collected from local abattoir and matured in culture medium at 38.5ºC, 5% CO₂ , 95% humidity for 22-24 hr. The matured oocytes were inseminated with capacitated spermatozoa in Brackett and Oliphant medium and resulted embryos were cultured in CO₂ incubator for 6-7 days to complete the developmental stages from two cells to blastocyst stage. Total RNA was extracted from immature oocytes (n = 100), mature oocytes (n = 100) and different stages of embryos such as 2 cell (n = 50), 4 cell (n = 25), 8 cell (n = 12), 16 cell (n = 6), morula (n = 5) and blastocyst (n = 3). The total RNA isolated from the oocytes and embryos was reverse transcribed and subjected to real-time polymerase chain reaction using sequence-specific primers and SYBR green as the DNA dye. On sequence analysis, the nucleotide sequence of sheep FGF2 exhibited highest sequence similarity with cattle (100%) and least with rat and mouse (69.2%). At the deduced amino acid level, a highest degree of similarity was noticed with cattle, buffalo, goat, pig, camel and horse (100%) and lowest degree of identity with rat, human and mouse (98.2%). The FGF2 mRNA expression was higher in immature and mature oocytes and gradually decreases from 2-cell stage of embryo to the blastocyst stage. More over a significant differences in FGF2 mRNA expression (p < .05) were observed between immature oocytes and all pre-implantation stages of embryo. It can be concluded that FGF-2 plays a significant role in pre-implantation and early development of embryos in sheep.

Fibroblast growth factor-2 expression in the preimplantation equine conceptus and endometrium of pregnant and cyclic mares

Uterine-derived growth factors and cytokines play essential roles in regulating preimplantation conceptus development. In several species, fibroblast growth factor-2 (FGF2) promotes embryogenesis, trophoblast cell migration, and adhesion. This study investigated mRNA expression for FGF2, its receptors (FGFR1-4), the activating factor FGF binding protein (FGF-BP) in equine endometrium and trophectoderm during early pregnancy and the estrous cycle, and localized FGF2 protein in both endometrium and conceptus tissues. FGF2, FGFRs1-4, and FGFBP mRNAs were expressed in endometrium throughout the estrous cycle and early pregnancy, and in days 14 to 28 conceptus membranes. FGF2 transcription was higher during estrus than on days 7 or 14 of diestrus, suggesting estrogen dependency. Endometrial expression of FGF2 mRNA and protein increased as pregnancy progressed from days 21 and day 28; FGF2 protein was localized predominantly in the luminal and glandular epithelium. FGF2 mRNA was detectable in trophectoderm from as early as day 14, and transcription and translation increased in day 21 and 28 allantochorion. FGF2 protein was localized mainly in the trophectoderm up to day 21 but was present in both trophectoderm and endoderm of day 28 allantochorion. FGFR1 mRNA was down-regulated in the endometrium at day 7 of diestrus but increased again by day 14. Gene expression for all of the FGFR2 splice variants, including FGFR2IIIc, was up-regulated during estrus. During early pregnancy, endometrial FGFR1 expression decreased, whereas FGFR2IIIc expression did not change. Conceptus mRNA expression for all FGFRs increased as pregnancy progressed. FGFBP expression remained unchanged in endometrium, but increased in the conceptus between days 14 and 28, suggesting a role in regulating FGF2 activity in the developing conceptus. We conclude that during weeks 3 and 4 of pregnancy, the equine endometrial epithelium produces FGF2, which may play a role in trophoblast development and adhesion.

Ovine endometrial expression of fibroblast growth factor (FGF) 2 and conceptus expression of FGF receptors during early pregnancy

In ruminants, conceptus development beyond the blastocyst state requires input from uterine-derived factors. Fibroblast growth factor 2 (FGF2) is expressed by the bovine endometrium throughout the estrus cycle and early pregnancy and stimulates trophectoderm expression of interferon-tau, the maternal recognition of pregnancy factor in ruminants. The objective of this study was to examine the expression of FGF2 in ovine endometrium and peri-attachment conceptuses and FGF receptors (FGFR) in conceptuses. FGF2 mRNA was present in the ovine endometrium with specific localization within the luminal and glandular epithelium. No pregnancy-dependent changes in endometrial FGF2 mRNA abundance were detected until placental attachment was well underway. FGF2 protein was detected in the uterine lumen throughout the estrous cycle and early pregnancy. Concentrations of luminal FGF2 protein did not differ based on pregnancy status. However, uterine luminal FGF2 protein levels increased at days 12-13 after estrus in both cyclic and pregnant ewes. Ovine conceptuses collected at days 14-19 after mating contained transcripts for FGF2 and FGFR types 1, 2 and 3. In summary, FGF2 is expressed by the ovine endometrium and conceptus during early pregnancy, and peri-attachment conceptuses possess several FGFR types. Concentrations of FGF2 protein in the uterine lumen increase coincident with the initiation of pregnancy recognition in ewes. These observations support the concept that FGF2 and potentially other FGFs may affect conceptus development and/or gene expression during early pregnancy in ruminants.

Fator de crescimento fibroblástico básico e seus receptores em relação à atividade proliferativa na placenta bubalina em diferentes fases da gestação

Estudou-se a distribuição espaço-temporal do fator de crescimento fibroblástico básico (bFGF), do receptor 1 do fator de crescimento fibroblástico (FGFR1) e do receptor 2 do fator de crescimento fibroblástico (FGFR2) na placenta bubalina, correlacionando-a à proliferação celular. Para a detecção do bFGF, FGFR1, FGFR2 e antígeno Ki-67, colheram-se 12 placentas de búfalas nos terços inicial, médio e final da gestação, em abatedouros, e realizaram-se testes de imunoistoquímica. Detectou-se e avaliou-se a expressão do bFGF, do FGFR1, do FGFR2 e do antígeno Ki-67 ao longo da gestação. No compartimento fetal da placenta, observaram-se correlações positivas entre a expressão do bFGF e Ki-67, entre FGFR1 e Ki-67 e entre FGFR2 com Ki-67 (r=0,313, 0,358 e 0,384, respectivamente). No epitélio e estroma maternos observaram-se altas correlações entre FGFR1 e Ki-67 (r=0,739 e r=0,511, respectivamente). Os resultados sugerem envolvimento do bFGF, FGFR1 e FGFR2 na proliferação do trofoblasto enquanto no compartimento materno da placenta bubalina apenas o FGFR1 atuaria como modulador dessa atividade.

Developmental and hormonal regulated gene expression of fibroblast growth factor 2 (FGF-2) and its receptors in porcine endometrium

This study examined the mRNA levels of the fibroblast growth factor 2 (FGF-2) and two of its receptors, FGFR1IIIc and FGFR2IIIc, at days 12 and 20 of the ovarian cycle (DC 12 and DC 20), days 1 and 12 of pregnancy (DP 1 and DP 12) as well as the influence of progesterone (P) and estradiolbenzoate (EB) on their expression in the endometrium of ovariectomized (ovx) gilts by real-time PCR. Proteins of FGF-2 and FGFR1 were immunolocalized. FGF-2 and FGFR2IIIc mRNAs were always found with a 5- to 30-fold higher absolute concentration compared to FGFR1IIIc. The latter transcript significantly declined between DP 1 and DP 12, whereas FGF-2 and FGFR2IIIc showed no significant changes at that time. FGF-2 transcription was greater at DC 20 than at DC 12, but significantly most transcripts were found in ovx gilts. EB induced a significant suppression of FGF-2 mRNA, an effect which was antagonized by P and even prevented by P+EB. FGFR1IIIc mRNA was significantly increased at DC 20, that of FGFR2IIIc at DC 12 displaying a 10 times higher absolute mRNA amount. Suppression of FGFR1IIIc mRNA by P was abolished by EB while P+EB attenuated this effect. FGFR2IIIc transcripts were equally restrained by P or EB while a combination of both slightly reduced such declines. Localization of FGF-2 and FGFR1 proteins in stromal, glandular and vascular compartments was effected by sex steroids. Both proteins were strongly expressed at DP 12 but not at DP 1. Summarized, differential temporal and spatial localization of FGF-2 and FGFR1 after response to sex steroids support a complex regulation of this ligand receptor system important for proliferation and differentiation of uterine cells including angiogenic processes. While FGFR1IIIc is presumed to be promoted by estradiol FGFR2IIIc appears to be dominated by progesterone implicating different biological importance for a functional endometrium.