Insulin-like growth factor I induces proliferation and migration of porcine trophectoderm cells through multiple cell signaling pathways, including protooncogenic protein kinase 1 and mitogen-activated protein kinase

Network pharmacology analysis of the regulatory effects and mechanisms of ALAE on sow reproduction in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Reproductive ability of sows is a primary element influencing the development of pig farming. Herbal extracts of Angelica sinensis (Oliv.) Diels, Astragalus mongholicus Bunge, Eucommia ulmoides Oliv., and Polypodium glycyrrhiza D.C.Eaton showed effects on improvement of reproduction in sows.

AIMS OF THE STUDY

To investigate the mechanism of the treatment effects by a compound of these four Chinese herbs in a 1:1:1:1 ratio (ALAE) on endometriosis, endometritis, uterine adhesion, intrauterine growth retardation, pre-eclampsia, and its enhancement of reproductive efficiency in sows.

MATERIALS AND METHODS

Active components of ALAE were identified by using ultra-performance liquid chromatography-mass spectrometry analysis and network pharmacology. Then we used the results to construct a visualization network. Key targets and pathways of ALAE involved in sow reproduction improvement were validated in sow animals and porcine endometrial epithelial cells (PEECs).

RESULTS

A total of 62 active compounds were found in ALAE (41 in Polypodium glycyrrhiza D.C.Eaton, 5 in Astragalus mongholicus Bunge, 11 in Eucommia ulmoides Oliv., 5 in Angelica sinensis (Oliv.) Diels) with 563 disease-related targets (e.g. caspase-3, EGFR, IL-6) involved in EGFR tyrosine kinase inhibitor resistance, PI3K-AKT, and other signaling pathways. Molecular docking results indicated GC41 (glabridin), GC18 (medicarpin), EGFR and CCND1 are possible key components and target proteins related to reproductive improvement in sows. In PEECs, EGFR expression decreased at the mRNA and protein levels by three doses (160, 320, and 640 μg/mL) of ALAE. The phosphorylation of downstream pathway PI3K-AKT1 was enhanced. The expression of inflammatory factors (IL-6, IL-1β), ESR1 and caspase-3 decreased through multiple pathways. Additionally, the expression levels of an anti-inflammatory factor (IL-10), angiogenesis-related factors (MMP9, PIGF, PPARγ, IgG), and placental junction-related factors (CTNNB1, occludin, and claudin1) increased. Furthermore, the total born number of piglets, the number of live and healthy litters were significantly increased. The number of stillbirths decreased by ALAE treatment in sow animals.

CONCLUSIONS

Dministration of ALAE significantly increased the total number of piglets born, the numbers of live and healthy litters and decreased the number of stillbirths through improving placental structure, attenuating inflammatory response, modulating placental angiogenesis and growth factor receptors in sows. The improvement of reproductive ability may be related to activation of the EGFR-PI3K-AKT1 pathway in PEECs. Moreover, ALAE maybe involved in modulation of estrogen receptors, apoptotic factors, and cell cycle proteins.

The importance of optimal body condition to maximise reproductive health and perinatal outcomes in pigs

Overnutrition or undernutrition during all or part of the reproductive cycle predisposes sows to metabolic consequences and poor reproductive health which contributes to a decrease in sow longevity and an increase in perinatal mortality. This represents not only an economic problem for the pig industry but also results in poor animal welfare. To maximise profitability and increase sustainability in pig production, it is pivotal to provide researchers and practitioners with synthesised information about the repercussions of maternal obesity or malnutrition on reproductive health and perinatal outcomes, and to pinpoint currently available nutritional managements to keep sows' body condition in an optimal range. Thus, the present review summarises recent work on the consequences of maternal malnutrition and highlights new findings.

In missed abortion the decrease of IGF-1 down-regulates PI3K/AKT signaling pathway reducing the secretion of progesterone and β-hCG

OBJECTIVE

To explore whether the reduction of IGF-1 in missed abortion down-regulates PI3K/AKT signaling pathway, thereby causing trophoblast cell apoptosis and reducing the secretion of β-hCG and progesterone.

DESIGN

12 pairs of serum and villous tissues were selected from missed abortion patients and normal early pregnant women who had terminated pregnancy by artificial abortion. The subjects in two groups had same age and gestational week. Wes Simple Western system and qRT-PCR were used to detect the expression of IGF-1, IGF-1R, PI3K/AKT signaling pathway and apoptosis-related factors in villous tissues. Radioimmunoassay and Enzyme-linked immunosorbent assay were used to detect β-hCG, progesterone and IGF-1 in serum.

RESULTS

The serum levels of β-hCG, progesterone and IGF-1 were decreased in missed abortion group than those in normal early pregnant women. In addition, compared with normal early pregnant women, the genes and proteins levels of IGF-1 and PI3K/AKT signaling pathway and anti-apoptosis related factors were significantly decreased.

CONCLUSIONS

Our results suggested that the reduction of IGF-1 in missed abortion patients could down-regulate the expression of PI3K/AKT signaling pathway, thereby increasing the apoptosis of trophoblast cells, leading to decreased secretion of β-hCG and progesterone, which may be one of the important mechanisms of missed abortion.

Global analysis of differential gene expression within the porcine conceptus transcriptome as it transitions through spherical, ovoid, and tubular morphologies during the initiation of elongation

This study aimed to identify transcriptome differences between distinct or transitional stage spherical, ovoid, and tubular porcine blastocysts throughout the initiation of elongation. We performed a global transcriptome analysis of differential gene expression using RNA‐Seq with high temporal resolution between spherical, ovoid, and tubular stage blastocysts at specific sequential stages of development from litters containing conceptus populations of distinct or transitional blastocysts. After RNA‐Seq analysis, significant differentially expressed genes (DEGs) and pathways were identified between distinct morphologies or sequential development stages. Overall, 1898 significant DEGs were identified between distinct spherical and ovoid morphologies, with 311 total DEGs between developmental stages throughout this first morphological transition, while 15 were identified between distinct ovoid and tubular, with eight total throughout these second morphological transition developmental stages. The high quantity of DEGs and pathways between conceptus stages throughout the spherical to ovoid transition suggests the importance of gene regulation during this first morphological transition for initiating elongation. Further, extensive DEG coverage of known elongation signaling pathways was illustrated from spherical to ovoid, and regulation of lipid signaling and membrane/ECM remodeling across these early conceptus stages were implicated as essential to this process, providing novel insights into potential mechanisms governing this rapid morphological change.

Transfer and Expression of Native Human Insulin-Like Growth Factor-1 in Tobacco Chloroplasts

Background

Insulin-like growth factor-1 (IGF-1), in addition to having insulin-like effects, has boosting effects on all cells in human body. Most of the recombinant IGF-1 required for patients suffering from its deficiency is currently produced by bacterial and yeast systems. Plant systems, especially chloroplasts, have many benefits for producing human blood proteins. Production costs are low in these systems, and their side effects are less than other systems.

Objectives

In this study, the transfer and expression of mature IGF-1 protein cDNA in tobacco chloroplasts under the control of strong plastid transcription and translation elements was evaluated.

Materials and Methods

The biolistic transformation method was used to transfer the IGF-1 gene cloned into the pRB94-IGF1 chloroplast vector. Homoplasmic transplastomic plants were produced through four selection rounds on the selective medium. Transfer of foreign genes to chloroplast genome was confirmed by PCR, Southern blotting and seed progeny test. RT-PCR and SDS-PAGE methods were used to evaluate the expression of IGF-1 gene in transgenic line.

Results

A truly transformed line was identified from selected seedlings by PCR method. The seed progeny test of 4^th-regeneration-round transgenic plants of this line showed maternal inheritance and homoplasmic level for the selectable marker gene, which confirms the transfer and expression of the marker gene in the chloroplast genome. The Southern blot test also confirmed the transfer of the IGF-1 gene into the chloroplast genome. RT-PCR test showed that IGF-1 gene transcription is performed correctly in transgenic plants. Finally, accumulation of IGF-1 protein in transgenic plants was detected by SDS-PAGE.

Conclusions

Successful transfer and expression of the native human IGF-1 gene in tobacco chloroplast genome is reported.

CGFe and TGF-β1 enhance viability and osteogenic differentiation of human dental pulp stem cells through the MAPK pathway

The present study aimed to evaluate the effects of concentrated growth factor exudate (CGFe) and TGF-β1 on the viability and osteogenic differentiation of human dental pulp stem cells (hDPSCs). CGFe was prepared from the peripheral blood of healthy donors (obtained with informed consent). STRO-1⁺ hDPSCs were isolated from dental pulp tissues and treated in four groups: i) Control; ii) TGF-β1 (1 ng/ml); iii) 100% CGFe; and iv) TGF-β1 (1 ng/ml) + 100% CGFe group. hDPSC viability was measured via MTT assay. The osteogenic differentiation of hDPSCs was quantified via alkaline phosphatase (ALP) activity, western blotting and reverse transcription-quantitative PCR assays. CGFe and TGF-β1 enhanced hDPSC viability, upregulated ALP activity, upregulated the expression of phosphorylated (p)-ERK1/2, p-JNK and p-p38 in hDPSCs, and promoted transcription and protein expression of osteogenic-related genes (bone sialoprotein, Runt-related transcription factor 2 and osteocalcin) in hDPSCs. The present study demonstrated that CGFe and TGF-β1 facilitated the viability and osteogenic differentiation of hDPSCs potentially through activation of the MAPK signaling pathway.

Altrenogest during early pregnancy modulates uterine glandular epithelium and endometrial growth factor expression at the time implantation in pigs

This study evaluated the effects of supplying altrenogest from day 6-12 of pregnancy on the endometrial glandular epithelium, corpora lutea (CL) morphology, and endometrial and CL gene expression. A total of 12 crossbred females (Landrace × Large White) were used. The females were assigned to 4 treatments according to a random design with a 2 × 2 factorial arrangement, with two categories (sow or gilt) and two treatments (non-treated and treated with altrenogest). On day 6 of pregnancy, animals were allocated to one of the following groups: non-treated (NT, n = 6; 3 sows and 3 gilts), and (T, n = 6; 3 sows and 3 gilts) treated daily with 20 mg of altrenogest, from day 6-12 of pregnancy. All animals were euthanized on day 13 of pregnancy. All CLs were individually weighed, and their volume were determined. The endometrial glandular density (GD), mean glandular area (MGA), and vascular density (VD) were determined by histomorphometric and immunohistochemical analyses. Endometrium samples were collected and analyzed by qRT-PCR to evaluate the abundance of transcripts for VEGF and IGF-I. Females in the T group had higher MGA (P < 0.05) compared to the NT group. There was no effect of treatment on GD or VD for both experimental groups. Sows in the T group had augmented expression of IGF-I (P < 0.05). Progestagen had no detrimental effect on CL morphology. In conclusion, altrenogest improves the uterine environment during the peri-implantation period in pigs without compromising corpora lutea development.

Protegrin-1 Regulates Porcine Granulosa Cell Proliferation via the EGFR-ERK1/2/p38 Signaling Pathway in vitro

Antimicrobial peptides (AMPs) are traditionally known to be essential components in host defense via their broad activities against bacteria, fungi, viruses, and protozoa. Their immunomodulatory properties have also recently received considerable attention in mammalian somatic tissues of various species. However, little is known regarding the role of AMPs in the development and maturation of ovarian follicles. Protegrin-1 (PG-1) is an antimicrobial peptide which is known to have potent antimicrobial activity against both gram positive and negative bacteria. Here we report that the PG-1 is present in the porcine ovarian follicular fluid. Treatment of granulosa cell with PG-1 enhanced granulosa cell proliferation in a dose-dependent manner. This is accompanied by increased expression of cell-cycle progression-related genes such as cyclin D1(CCND1), cyclin D2 (CCND2), and cyclin B1(CCNB1). Additionally, Western blot analysis showed that PG-1 increased phosphorylated epidermal growth factor receptor (EGFR), and the phosphorylated-/total extracellular signal-regulated kinase (ERK)1/2 ratio. Pretreatment with either U0126, a specific ERK1/2 phosphorylation inhibitor, or EGFR kinase inhibitor, AG1478, blocked the PG-1 induced proliferation. Moreover, luciferase reporter assay revealed that ETS domain-containing protein-1 (Elk1) C/EBP homologous protein (CHOP), and the transcription activators downstream of the MAPK pathway, were activated by PG-1. These data collectively suggest that PG-1 may regulate pig granulosa cell proliferation via EGFR-MAPK pathway., Hence, our finding offers insights into the role of antimicrobial peptides on follicular development regulation.

Melatonin improves uterine-conceptus interaction via regulation of SIRT1 during early pregnancy

Melatonin has been shown to improve in vitro fertilization and offspring survival after bacterial infection, but its role in regulating maternal-fetal communication during early pregnancy has not been investigated. Results of this study demonstrated expression of abundant melatonin receptors in conceptus and endometrium during early pregnancy. In gilts, expression of melatonin receptor 1A (MTNR1A or MT1) and melatonin receptor 1B (MTNR1B or MT2) increased in trophectoderm (Tr) and uterine luminal epithelium (LE) with advancing days during early pregnancy in a different manner. Melatonin increased proliferation and migration of porcine trophectoderm (pTr) cell, the percent pTr cells in the G2 phase of the cell cycle, and the expression of implantation-related genes by pTr cells and endometrial luminal epithelium (pLE). Melatonin also attenuated the production of LPS-induced pro-inflammatory cytokines and tunicamycin-induced endoplasmic reticulum (ER) stress-sensing proteins. The expression of sirtuin 1 (SIRT1) as a potential target of melatonin increased between Days 9 and 14 of gestation. Co-treatment with SIRT1 inhibitor EX527 and melatonin restored cell-cell interactions through PI3K and MAPK signaling. Knockdown of SIRT1 decreased the expression of implantation-related genes, as well as migration of pTr and pLE cells. The expression of microRNAs regulated by SIRT1 was suppressed in response to melatonin. Furthermore, melatonin significantly increased lipopolysaccharide (LPS)-reduced fertilization and embryogenesis in zebrafish model. These results suggest that melatonin may improve the uterine-conceptus interactions via the regulation of SIRT1 during early pregnancy.

Effects of N-carbamylglutamate on steroidogenesis and relative abundances of mRNA transcripts in pig placental trophoblasts

Supplementation of N-carbamylglutamate (NCG) improves gestation outcomes, with increased piglet within-litter uniformity of birth weight and reduced peripheral steroid concentrations in pregnant sows and ewes. It was hypothesized that the effect of NCG on placental function results from direct effects on the placental trophoblasts. There, therefore, was investigation of the effects of NCG on pig placental trophoblast (pTr) steroidogenesis, mRNA transcript abundance, and cell proliferation in vitro. The pTr were treated with NCG in serum-free medium for 24-48 h. Treatment with NCG inhibited pTr progesterone, androstenedione, testosterone (all P <  0.01), and estradiol (P <  0.05) production, whereas it promoted (P <  0.05) pTr proliferation. Treatment with NCG suppressed (P <  0.05) the relative abundances of CYP11A1, CYP19A1, and CASP3 and increased abundances of CCDN1 (P <  0.01) and CDK4 (P <  0.05) mRNA transcripts in pTr, whereas NCG treatment had no effect (P >  0.10) on relative abundances of StAR, HSD17B4, or HSD3B mRNA transcripts. Treatments with NCG can increase pTr cell numbers of sows through upregulating CCND1 and CDK4 and suppressing CASP3 mRNA transcript abundances, while modulating steroidogenesis through effects on CYP11A1 and CYP19A1 mRNA transcript abundances. It is concluded that NCG may have a direct action on pTr and may regulate placental function by suppressing pTr differentiation as a consequence of lesser steroid synthesis while promoting pTr proliferation and inhibiting apoptosis in sows.

Low body mass index is associated with ectopic pregnancy following assisted reproductive techniques: a retrospective study

OBJECTIVE

To investigate the association between body mass index (BMI) and ectopic pregnancy (EP) following embryo transfer (ET).

DESIGN

Retrospective cohort study.

SETTING

University-affiliated hospital.

POPULATION

A total of 16 378 pregnancies derived from either fresh ET or frozen-thawed ET between January 2008 and December 2017.

METHODS

We used the generalised estimating equation (GEE) to analyse the association between BMI categories and EP, as one woman may contribute to more than one pregnancy. Generalised additive models were also used to demonstrate the non-linear association. Models were adjusted for age, parity, gravidity, previous history of ectopic pregnancy, duration of infertility, polycystic ovary syndrome, endometriosis, diagnosis of tubal problems, ovarian reserve markers, ovarian stimulation parameters, insemination protocol, endometrial thickness and embryo transfer policies.

MAIN OUTCOME MEASURES

Ectopic pregnancy.

RESULTS

According to the WHO criteria, the number of cycles with low (<18.5 kg/m² ), normal (18.5-24.9 kg/m² ) and high (≥25 kg/m² ) BMI were 2155, 13 447 and 776, respectively. In comparison with the normal BMI group, the rate of EP was significantly increased in the low BMI group (2.92% versus 2.02%, relative risk 1.45, 95% CI 1.11-1.90), but not in the high BMI group (2.84%, relative risk 1.41, 95% CI 0.92-2.20). Adjusted for confounding factors, the odds ratio for EP comparing low BMI versus normal BMI was 1.61 (95% CI 1.19-2.16) and that comparing high BMI versus normal BMI was 1.12 (95% CI 0.72-1.76).

CONCLUSIONS

Low BMI is associated with an increased risk of EP.

TWEETABLE ABSTRACT

The ectopic pregnancy rate after embryo transfer for lean women is higher than that for women of normal weight.

Growth factor modulation of equine trophoblast mitosis and prostaglandin gene expression

 To provide insight into maternal recognition of pregnancy control in equids, the mitogenic and developmental effects of endometrium-expressed growth factors (epidermal growth factor (EGF), fibroblast growth factor 2 (FGF2), hepatocyte growth factor (HGF), and insulin-like growth factor-1 (IGF-1)) were examined in equine iTr cells, an equine trophectoderm cell line. Initial western blots revealed that HGF and IGF-1 stimulate phosphorylation of AKT serine/threonine kinase 1 (AKT1) and EGF, FGF2, or HGF resulted in phosphorylation of both extracellular signal-regulated kinase 1 (ERK1) and ERK2. Mitotic activity was stimulated (P < 0.05) by EGF, FGF2, and HGF. Chemical disruption of mitogen-activated protein kinase kinases 1 and 2 (MEK1/2) phosphorylation suppresses (P < 0.05) proliferation in control and growth factor treated cells demonstrating a dependence on ERK1/2 for mitotic activity. Treatment of iTr cells with EGF or HGF in the presence of an AKT1 inhibitor prohibits (P < 0.05) growth factor stimulated proliferation. The effect of EGF, FGF2, HGF, and IGF-1 on steroid biosynthetic enzyme gene expression, including prostaglandin-endoperoxide synthase 2 (PTGS2), was determined by real-time PCR. Neither EGF, FGF2, nor IGF-1 affected PTGS2 expression while HGF caused a two-fold increase (P < 0.05) in expression. Co-supplementation with HGF and an AKT1 inhibitor did not block PTGS2 expression, whereas providing an MEK1/2 inhibitor prevented (P < 0.05) the HGF-mediated increase in PTGS2. These results provide novel evidence of a role for HGF in equine trophectoderm proliferation and prostaglandin biosynthesis.

ROS-induced autophagy regulates porcine trophectoderm cell apoptosis, proliferation, and differentiation

Significant embryo loss remains a serious problem in pig production. Reactive oxygen species (ROS) play a critical role in embryonic implantation and placentation. However, the potential mechanism of ROS on porcine trophectoderm (pTr) cell fate during the peri-implantation period has not been investigated. This study aimed to elucidate the effects of ROS on pTr cell phenotypes and the regulatory role in cell attachment and differentiation. Herein, results showed that exogenous H₂O₂ inhibited pTr cell viability, arrested the cell cycle at S and G2/M phases, and increased cell apoptosis and autophagy protein light chain 3B and Beclin-1, whereas these effects were reversed by different concentrations of N-acetyl-l-cysteine (NAC) posttreatment. In addition, NAC abolished H₂O₂-induced autophagic flux, inhibited intracellular and mitochondrial ROS, and restored expression of genes important for mitochondrial DNA and biogenesis, cell attachment, and differentiation. NAC reversed H₂O₂-activated MAPK and Akt/mammalian target of rapamycin pathways in dose-dependent manners. Furthermore, analyses with pharmacological and RNA interference approaches suggested that autophagy regulated cell apoptosis and gene expression of caudal-related homeobox 2 and IL-1β. Collectively, these results provide new insights into the role of the ROS-induced autophagy in pTr cell apoptosis, attachment, and differentiation, indicating a promising target for decreasing porcine conceptus loss during the peri-implantation period.

FUT8 drives the proliferation and invasion of trophoblastic cells via IGF-1/IGF-1R signaling pathway

INTRODUCTION

Trophoblast proliferation and invasion are essential for embryo implantation and placentation. Protein glycosylation is one of the most common and vital post-translational modifications, regulates protein physical and biochemical properties. FUT8 is the only known fucosyltransferase responsible for catalyzing α1,6-fucosylation in mammals, and α1,6-fucosylated glycoproteins are found to participate in various physiopathological processes. However, whether FUT8/α1,6-fucosylation modulates the functions of trophoblastic cells remains elusive.

METHODS

FUT8 in human placenta villi during 6-8 gestational weeks and trophoblastic cells were detected by Western blot and immunofluorescent staining. α1,6-fucosylation in tissues or cells were measured by Lectin LCA (Lens culinaris) fluorescent staining and Lectin blot. FUT8 expression was down-regulated by siRNA transfection in JAR and JEG-3 cells, and cell viability, motility and invasiveness ability were detected by the functional experiments. α1,6-fucosylation of insulin-like growth factor receptor (IGF-1R) was examined by immunoprecipitation, and the amount of phosphorylated IGF-1R was detected in FUT8 down-regulated JAR cells.

RESULTS

Human placenta villi and trophoblastic cells expressed FUT8/α1,6-fucosylation. Knockdown FUT8 by siRNA transfection suppressed the proliferation, epithelial-mesenchymal transition, migration and invasion of JAR and JEG-3 cells. Furthermore, we found that FUT8 modified the α1,6-fucosylation of IGF-1R, and regulated IGF-1 dependent activation of IGF-1R, MAPK and PI3K/Akt signaling pathways in JAR cells.

CONCLUSIONS

Our results implicate a critical role for FUT8 in maintaining the normal functions of trophoblastic cells, suggesting manipulating FUT8 may be an effective approach in pregnancy.

Reactive oxygen species mediated placental oxidative stress, mitochondrial content, and cell cycle progression through mitogen-activated protein kinases in intrauterine growth restricted pigs

Intrauterine growth restriction (IUGR) remains a significant obstacle in pig production; however, information regarding the relationship between reactive oxygen species (ROS)-induced placental dysfunction and IUGR is still unknown. This study aimed to explore the placental redox status, mitochondrial content, cellular progression, and mitogen-activated protein kinase (MAPK) pathways in IUGR. Placental tissues were collected from normal intrauterine gestation (NIUG) and IUGR fetuses at delivery. Compared with the NIUG, placental ROS production, lipid peroxidation, and DNA damage were increased in IUGR. Placental mitochondrial DNA (mtDNA) content and mtDNA-encoded gene expression decreased in IUGR. Moreover, p21 phosphorylation increased, cyclin E expression decreased in IUGR cases, which showed senescence characteristics. Analysis of signaling pathways showed that the ERK1/2 phosphorylation increased whereas the p38 and JNK phosphorylation decreased in IUGR. In cultured porcine trophectoderm (pTr) cells, exogenous H₂O₂ increased intracellular ROS production, decreased cell viability in a dose-dependent manner. Cell cycle distribution was found to arrest in S and G2/M phases. Our findings suggested that IUGR was associated with greater placental ROS and oxidative injury, which might be a factor that resulted in lower mitochondrial content, microvilli loss and senescence, and activation of MAPK pathways.

Iloprost supports early development of in vitro-produced porcine embryos through activation of the phosphatidylinositol 3-kinase/AKT signalling pathway

Despite evidence of the presence of prostaglandin (PG) I₂ in mammalian oviducts, its role in early development of in vitro-produced (IVP) embryos is largely unknown. Thus, in the present study we examined the effects of iloprost, a PGI₂ analogue, on the in vitro developmental competence of early porcine embryos and the underlying mechanism(s). To examine the effects of iloprost on the development rate of IVF embryos, iloprost was added to the in vitro culture (IVC) medium and cultured for 6 days. Supplementation of the IVC medium with iloprost significantly improved developmental parameters, such as blastocyst formation rate, the trophectoderm:inner cell mass ratio and cell survival in IVF and parthenogenetically activated (PA) embryos. In addition, post-blastulation development into the expanded blastocyst stage was improved in iloprost-treated groups compared with controls. Interestingly, the phosphatidylinositol 3-kinase (PI3K)/AKT signalling pathway was significantly activated by iloprost supplementation in a concentration-dependent manner (10-1000nM), and the beneficial effects of iloprost on the early development of porcine IVF and PA embryos was completely ablated by treatment with 2.5μM wortmannin, a PI3K/AKT signalling inhibitor. Importantly, expression of the PI3K/AKT signalling pathway was significantly reduced in somatic cell nuclear transfer (SCNT) compared with IVF embryos, and iloprost supported the early development of SCNT embryos, as was the case for IVF and PA embryos, suggesting a consistent effect of iloprost on the IVC of IVP porcine embryos. Together, these results indicate that iloprost can be a useful IVC supplement for production of IVP early porcine embryos with high developmental competence.

Uterine responses to early pre-attachment embryos in the domestic dog and comparisons with other domestic animal species

In the dog, there is no luteolysis in the absence of pregnancy. Thus, this species lacks any anti-luteolytic endocrine signal as found in other species that modulate uterine function during the critical period of pregnancy establishment. Nevertheless, in the dog an embryo-maternal communication must occur in order to prevent rejection of embryos. Based on this hypothesis, we performed microarray analysis of canine uterine samples collected during pre-attachment phase (days 10-12) and in corresponding non-pregnant controls, in order to elucidate the embryo attachment signal. An additional goal was to identify differences in uterine responses to pre-attachment embryos between dogs and other mammalian species exhibiting different reproductive patterns with regard to luteolysis, implantation, and preparation for placentation. Therefore, the canine microarray data were compared with gene sets from pigs, cattle, horses, and humans. We found 412 genes differentially regulated between the two experimental groups. The functional terms most strongly enriched in response to pre-attachment embryos related to extracellular matrix function and remodeling, and to immune and inflammatory responses. Several candidate genes were validated by semi-quantitative PCR. When compared with other species, best matches were found with human and equine counterparts. Especially for the pig, the majority of overlapping genes showed opposite expression patterns. Interestingly, 1926 genes did not pair with any of the other gene sets. Using a microarray approach, we report the uterine changes in the dog driven by the presence of embryos and compare these results with datasets from other mammalian species, finding common-, contrary-, and exclusively canine-regulated genes.

Endometrial response to conceptus-derived estrogen and interleukin-1β at the time of implantation in pigs

The establishment of pregnancy is a complex process that requires a well-coordinated interaction between the implanting conceptus and the maternal uterus. In pigs, the conceptus undergoes dramatic morphological and functional changes at the time of implantation and introduces various factors, including estrogens and cytokines, interleukin-1β2 (IL1B2), interferon-γ (IFNG), and IFN-δ (IFND), into the uterine lumen. In response to ovarian steroid hormones and conceptus-derived factors, the uterine endometrium becomes receptive to the implanting conceptus by changing its expression of cell adhesion molecules, secretory activity, and immune response. Conceptus-derived estrogens act as a signal for maternal recognition of pregnancy by changing the direction of prostaglandin (PG) F_2α from the uterine vasculature to the uterine lumen. Estrogens also induce the expression of many endometrial genes, including genes related to growth factors, the synthesis and transport of PGs, and immunity. IL1B2, a pro-inflammatory cytokine, is produced by the elongating conceptus. The direct effect of IL1B2 on endometrial function is not fully understood. IL1B activates the expression of endometrial genes, including the genes involved in IL1B signaling and PG synthesis and transport. In addition, estrogen or IL1B stimulates endometrial expression of IFN signaling molecules, suggesting that estrogen and IL1B act cooperatively in priming the endometrial function of conceptus-produced IFNG and IFND that, in turn, modulate endometrial immune response during early pregnancy. This review addresses information about maternal-conceptus interactions with respect to endometrial gene expression in response to conceptus-derived factors, focusing on the roles of estrogen and IL1B during early pregnancy in pigs.

Stimulatory effects of fibroblast growth factor 2 on proliferation and migration of uterine luminal epithelial cells during early pregnancy

Fibroblast growth factor 2 (FGF2) is a mitogen that induces proliferation, differentiation, and migration of cells, as well as angiogenesis and carcinogenesis via autocrine or paracrine actions. Fibroblast growth factor 2 expression is abundant in porcine conceptuses and endometrium during the estrous cycle and peri-implantation period of pregnancy. However, its intracellular actions in uterine epithelial cells have not been reported. The results of this study indicated abundant expression of FGFR1 and FGFR2 predominantly in uterine luminal and glandular epithelia during early pregnancy and that their expression decreased with increasing parity of the sows. Treatment of porcine uterine luminal epithelial (pLE) cells with FGF2 increased proliferation and DNA replication based on increases in proliferating cell nuclear antigen (PCNA) and initiation of G1/S phase progression. In addition, FGF2 increases phosphorylation of AKT, P70S6K, S6, ERK1/2, JNK, P38, and P90RSK in a time-dependent manner, and increases in their expression was suppressed by Wortmannin (a phosphatidylinositol 3-kinase [PI3K] inhibitor), U0126 (an ERK1/2 inhibitor), SP600125 (a JNK inhibitor), and SB203580 (a P38 inhibitor) based on western blot analyses. Also, the abundance of cytoplasmic p-AKT protein was decreased by Wortmannin and U0126, and p-ERK1/2 protein was reduced only by U0126. Furthermore, inhibition of each signal transduction protein reduced the ability of FGF2 to stimulate proliferation and migration of pLE cells. Collectively, these results indicate that activation of FGFR1 and FGFR2 by uterine- and endometrial-derived FGF2 stimulates PI3K/AKT and mitogen-activated protein kinase pathways for development of the porcine uterus and improvement of litter size.

IGF-I regulates HT1080 fibrosarcoma cell migration through a syndecan-2/Erk/ezrin signaling axis

Fibrosarcoma is a tumor of mesenchymal origin, originating from fibroblasts. IGF-I is an anabolic growth factor which exhibits significant involvement in cancer progression. In this study, we investigated the possible participation of syndecan-2 (SDC-2), a cell membrane heparan sulfate (HS) proteoglycan on IGF-I dependent fibrosarcoma cell motility. Our results demonstrate that SDC-2-deficient HT1080 cells exhibit attenuated IGF-I-dependent chemotactic migration (p < 0.001). SDC-2 was found to co-localize to IGF-I receptor (IGF-IR) in a manner dependent on IGF-I activity (P ≤ 0.01). In parallel, the downregulation of SDC-2 significantly inhibited both basal and due to IGF-I action ERK1/2 activation, (p < 0.001). The phosphorylation levels of ezrin (Thr567), which is suggested to act as a signaling bridge between the cellular membrane receptors and actin cytoskeleton, were strongly enhanced by IGF-I at both 1h and 24h (p < 0.05; p < 0.01). The formation of an immunoprecipitative complex revealed an association between SDC2 and ezrin which was enhanced through IGF-I action (p < 0.05). Immunoflourescence demonstrated a co-localization of IGF-IR, SDC2 and ezrin upregulated by IGF-I action. IGF-I enhanced actin polymerization and ezrin/actin specific localization to cell membranes. Finally, treatment with IGF-I strongly increased SDC2 expression at both the mRNA and protein level (p < 0.001). Therefore, we propose a novel SDC2-dependent mechanism, where SDC2 is co-localized with IGF-IR and enhances its' IGFI-dependent downstream signaling. SDC2 mediates directly IGFI-induced ERK1/2 activation, it recruits ezrin, contributes to actin polymerization and ezrin/actin specific localization to cell membranes, ultimately facilitating the progression of IGFI-dependent fibrosarcoma cell migration.

Role of androgen receptor on cyclic mechanical stretch-regulated proliferation of C2C12 myoblasts and its upstream signals: IGF-1-mediated PI3K/Akt and MAPKs pathways

OBJECTS

To detect the effects of androgen receptor (AR) on cyclic mechanical stretch-modulated proliferation of C2C12 myoblasts and its pathways: roles of IGF-1, PI3K and MAPK.

METHODS

C2C12 were randomly divided into five groups: un-stretched control, six or 8 h of fifteen percent stretch, and six or 8 h of twenty percent stretch. Cyclic mechanical stretch of C2C12 were completed using a computer-controlled FlexCell Strain Unit. Cell proliferation and IGF-1 concentration in medium were detected by CCK8 and ELISA, respectively. Expressions of AR and IGF-1R, and expressions and activities of PI3K, p38 and ERK1/2 in stretched C2C12 cells were determined by Western blot.

RESULTS

①The proliferation of C2C12 cells, IGF-1 concentration in medium, expressions of AR and IGF-1R, and activities of PI3K, p38 and ERK1/2 were increased by 6 h of fifteen percent stretch, while decreased by twenty percent stretch for six or 8 h ②The fifteen percent stretch-increased proliferation of C2C12 cells was reversed by AR inhibitor, Flutamide. ③The increases of AR expression, activities of PI3K, p38 and ERK1/2 resulted from fifteen percent stretch were attenuated by IGF-1 neutralizing antibody, while twenty percent stretch-induced decreases of the above indicators were enhanced by recombinant IGF-1. ④Specific inhibitors of p38, ERK1/2 and PI3K all decreased the expression of AR in fifteen percent and twenty percent of stretched C2C12 cells.

CONCLUSIONS

Cyclic mechanical stretch modulated the proliferation of C2C12 cells, which may be attributed to the alterations of AR via IGF-1-PI3K/Akt and IGF-1-MAPK (p38, ERK1/2) pathways in C2C12 cells.

Placental phenotype and the insulin-like growth factors: resource allocation to fetal growth

The placenta is the main determinant of fetal growth and development in utero. It supplies all the nutrients and oxygen required for fetal growth and secretes hormones that facilitate maternal allocation of nutrients to the fetus. Furthermore, the placenta responds to nutritional and metabolic signals in the mother by altering its structural and functional phenotype, which can lead to changes in maternal resource allocation to the fetus. The molecular mechanisms by which the placenta senses and responds to environmental cues are poorly understood. This review discusses the role of the insulin-like growth factors (IGFs) in controlling placental resource allocation to fetal growth, particularly in response to adverse gestational environments. In particular, it assesses the impact of the IGFs and their signalling machinery on placental morphogenesis, substrate transport and hormone secretion, primarily in the laboratory species, although it draws on data from human and other species where relevant. It also considers the role of the IGFs as environmental signals in linking resource availability to fetal growth through changes in the morphological and functional phenotype of the placenta. As altered fetal growth is associated with increased perinatal morbidity and mortality and a greater risk of developing adult-onset diseases in later life, understanding the role of IGFs during pregnancy in regulating placental resource allocation to fetal growth is important for identifying the mechanisms underlying the developmental programming of offspring phenotype by suboptimal intrauterine growth.

Brain-derived neurotrophic factor improves proliferation of endometrial epithelial cells by inhibition of endoplasmic reticulum stress during early pregnancy

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family binds to two transmembrane receptors; neurotrophic receptor tyrosine kinase 2 (NTRK2) with high affinity and p75 with low affinity. Although BDNF-NTRK2 signaling in the central nervous system is known, signaling in the female reproductive system is unknown. Therefore, we determined effects of BDNF on porcine endometrial luminal epithelial (pLE) cells isolated from Day 12 of pregnancy, as well as expression of BDNF and NTRK2 in endometria of cyclic and pregnant pigs. BDNF-NTRK2 genes were expressed in uterine glandular (GE) and luminal (LE) epithelia during early pregnancy. In addition, their expression in uterine GE and LE decreased with increasing parity of sows. Recombinant BDNF increased proliferation in pLE cells in a dose-dependent, as well as expression of PCNA and Cyclin D1 in nuclei of pLE cells. BDNF also activated phosphorylation of AKT, P70S6K, S6, ERK1/2, JNK, P38 proteins in pLE cells. In addition, cell death resulting from tunicamycin-induced ER stress was prevented when pLE cells were treated with the combination of tunicamycin and BDNF which also decreased cells in the Sub-G₁ phase of the cell cycle. Furthermore, tunicamycin-induced unfolded protein response genes were mostly down-regulated to the basal levels as compared to non-treated pLE cells. Our finding suggests that BDNF acts via NTRK2 to induce development of pLE cells for maintenance of implantation and pregnancy by activating cell signaling via the PI3K and MAPK pathways and by inhibiting ER stress.

Cellular Localization and Regulation of Expression of the PLET1 Gene in Porcine Placenta

The placenta expressed transcript 1 (PLET1) gene, which is expressed in placentas of pigs and mice, has been found to have a potential role in trophoblast cell fate decision in mice. Results of this study showed that the porcine PLET1 mRNA and protein were expressed exclusively in trophoblast cells on Days 15, 26, 50, and 95 of gestation (gestation length in the pig is 114 days), indicating that the PLET1 could be a useful marker for porcine trophoblast cells. Additionally, PLET1 protein was found to be redistributed from cytoplasm to the apical side of trophoblast cells as gestation progresses, which suggests a role of PLET1 in the establishment of a stable trophoblast and endometrial epithelial layers. In addition, two transcripts that differ in the 3′ UTR length but encode identical protein were identified to be generated by the alternative cleavage and polyadenylation (APA), and the expression of PLET1-L transcript was significantly upregulated in porcine placentas as gestation progresses. Furthermore, we demonstrated the interaction between the miR-365-3p and PLET1 gene using luciferase assay system. Our findings imply an important role of PLET1 in the placental development in pigs.

Decreased Serum IGF-1/IGFBP-3 Molar Ratio is Associated with Executive Function Behaviors in Type 2 Diabetic Patients with Mild Cognitive Impairment

BACKGROUND

Insulin-like growth factor (IGF)-1, through insulin/IGF-1 signaling pathway, is involved in the pathogenesis of type 2 diabetes mellitus (T2DM) and Alzheimer's disease.

OBJECTIVE

This study aimed to assess the association of serum IGF-1 and IGF binding protein (IGFBP)-3 levels with cognition status and to determine whether IGF-1 rs972936 polymorphism is associated with T2DM with mild cognitive impairment (MCI).

METHODS

A total of 150 T2DM patients, 75 satisfying the MCI diagnostic criteria and 75 exhibiting healthy cognition, were enrolled in this study. The cognitive function of the subjects was extensively assessed. Serum IGF-1 and IGFBP-3 levels were measured through enzyme-linked immunosorbent assay; IGF-1/IGFBP-3 molar ratio was calculated. Single nucleotide polymorphisms of the IGF-1-(rs972936) gene were analyzed.

RESULTS

Serum IGF-1/IGFBP-3 molar ratio in MCI patients was significantly lower than that in the control group (p = 0.003). Significant negative correlations were found between IGF-1/IGFBP-3 molar ratio and Trail Making Test A and B (TMT-A and TMT-B) scores (p = 0.003; p <  0.001, respectively), which indicated executive function. Further multiple step-wise regression analysis revealed that the TMT-A or TMT-B score was significantly associated only with serum IGF-1/IGFBP-3 molar ratio (p = 0.016; p <  0.001, respectively). No significant difference was found in the genotype or allele distribution of IGF-1 rs972936 polymorphism between MCI and control groups.

CONCLUSIONS

A low serum IGF-1/IGFBP-3 molar ratio is associated with the pathogenesis of MCI, particularly executive function in T2DM populations. Further investigation with a large population size should be conducted to confirm this observed association.

Fibroblast growth factor 4-induced migration of porcine trophectoderm cells is mediated via the AKT cell signaling pathway

During early pregnancy, a well-coordinated communication network between the conceptus and maternal uterus is especially crucial in pigs in which there is a protracted pre-attachment phase prior to implantation. This network is regulated by an astonishing number of molecules such as growth factors. Fibroblast growth factor 4 (FGF4) is a multipotent growth factor that elicits diverse biological actions on various types of cells and tissues. In pigs, FGF4 and its receptors are expressed in the uterine endometrium and conceptus during early pregnancy, but less is known about the FGF4-mediated regulation of conceptus growth during peri-implantation period of pregnancy. Therefore, the aims of the present study were to investigate: 1) expression of endometrial FGF4 mRNA during early pregnancy; 2) up-regulation of FGF receptor expression in porcine trophectoderm (pTr) cells in response to FGF4; and 3) FGF-induced intracellular signaling and cellular activities in pTr cells. In vitro cultured pTr cells incubated with different concentrations of recombinant FGF4 (0-50 ng/ml) responded with a dose-dependent increase in AKT phosphorylation of 2.9-fold at 20 ng/ml FGF4. Within 30 min after treatment with 20 ng/ml FGF4, the abundances of p-AKT, p-P90RSK and p-RPS6 proteins increased 2.1-, 5.2- and 3.2-fold, respectively, and then returned to basal levels by 120 min. To ensure that the stimulatory effect of FGF4 on AKT signaling was p-AKT-dependent, pTr cells were pre-incubated with an AKT inhibitor (LY294002) for 1 h prior to FGF4 treatment. 20 μM of LY294002 decreased FGF4-induced p-AKT, p-P90RSK and p-RPS6 proteins. Immunofluorescence analyses revealed that p-RPS6 proteins were abundant within the cytoplasm of FGF4-treated cells, but present at basal levels in the presence of LY294002. Furthermore, FGF4 increased migration of pTr cells and LY294002 significantly reduced this effect. Results of the present study suggest that activation of the FGF receptor(s) on trophectoderm cells by FGF4 secreted by conceptus/endometrium transduces its signal through the phosphatidylinositol 3-kinase (PI3K)/AKT pathway which is linked to migration of trophectoderm cells that is critical to development of the porcine conceptus.

Cytokines from the pig conceptus: roles in conceptus development in pigs

Establishment of pregnancy in pigs involves maintaining progesterone secretion from the corpora lutea in addition to regulating a sensitive interplay between the maternal immune system and attachment of the rapidly expanding trophoblast for nutrient absorption. The peri-implantation period of rapid trophoblastic elongation followed by attachment to the maternal uterine endometrium is critical for establishing a sufficient placental-uterine interface for subsequent nutrient transport for fetal survival to term, but is also marked by the required conceptus release of factors involved with stimulating uterine secretion of histotroph and modulation of the maternal immune system. Many endometrial genes activated by the conceptus secretory factors stimulate a tightly controlled proinflammatory response within the uterus. A number of the cytokines released by the elongating conceptuses stimulate inducible transcription factors such as nuclear factor kappa B (NFKB) potentially regulating the maternal uterine proinflammatory and immune response. This review will establish the current knowledge for the role of conceptus cytokine production and release in early development and establishment of pregnancy in the pig.

Expression, activation, and role of AKT isoforms in the uterus

The three isoforms of AKT: AKT1, AKT2, and AKT3, are crucial regulators of both normal and pathological cellular processes. Each of these isoforms exhibits a high level of homology and functional redundancy with each other. However, while being highly similar and structurally homologous, a rising amount of evidence is showing that each isoform possesses specific targets as well as preferential subcellular localization. The role of AKT has been studied extensively in reproductive processes, but isoform-specific roles are yet to be fully understood. This review will focus on the role of AKT in the uterus and its function in processes related to cell death and proliferation such as embryo implantation, decidualization, endometriosis, and endometrial cancer in an isoform-centric manner. In this review, we will cover the activation of AKT in various settings, localization of isoforms in subcellular compartments, and the effect of isoform expression on cellular processes. To fully understand the dynamic molecular processes taking place in the uterus, it is crucial that we better understand the physiological role of AKT isoforms as well as their function in the emergence of diseases.