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

Recombinant fibroblast growth factor 4 ameliorates axonal regeneration and functional recovery in acute spinal cord injury through altering microglia/macrophage phenotype

Neuroinflammation is one of the extensive secondary injury processes that aggravate metabolic and cellular dysfunction and tissue loss following spinal cord injury (SCI). Thus, an anti-inflammatory strategy is crucial for modulating structural and functional restoration during the stage of acute and chronic SCI. Recombinant fibroblast growth factor 4 (rFGF4) has eliminated its mitogenic activity and demonstrated a metabolic regulator for alleviating hyperglycemia in type 2 diabetes and liver injury in non-alcoholic steatohepatitis. However, it remains to be explored whether or not rFGF4 has a neuroprotective effect for restoring neurological disorders, such as SCI. Here, we identified that rFGF4 could polarize microglia/macrophages into the restorative M2 subtype, thus exerting an anti-inflammatory effect to promote neurological functional recovery and nerve fiber regeneration after SCI. Importantly, these effects by rFGF4 were related to triggering PI3K/AKT/GSK3β and attenuating TLR4/NF-κB signaling axes. Conversely, gene silencing of the PI3K/AKT/GSK3β signaling or pharmacological reactivation of the TLR4/NF-κB axis aggravated inflammatory reaction. Thus, our findings highlight rFGF4 as a potentially therapeutic regulator for repairing SCI, and its outstanding effect is associated with regulating macrophage/microglial polarization.

Chemerin affects the expression of angiogenesis-related factors in the porcine endometrium during early pregnancy and the oestrous cycle: an in vitro study

CONTEXT

The appropriate course of angiogenesis in the endometrium is crucial for pregnancy establishment and maintenance. Very little is known about the factors linking vessel formation and immune system functioning.

AIMS

We hypothesised that chemerin, an adipokine known for its involvement in the regulation of energy balance and immunological functions, may act as a potent regulator of endometrial angiogenesis during early pregnancy in pigs.

METHODS

Porcine endometrial tissue explants were obtained from pregnant pigs on days 10-11, 12-13, 15-16 and 27-28, and on days 10-12 of the oestrous cycle. The explants were in vitro cultured for 24h in the presence of chemerin (100, 200ng/mL) or in medium alone (control). We evaluated the in vitro effect of chemerin on the secretion of vascular endothelial growth factors A-D (VEGF-A-D), placental growth factor (PlGF), basic fibroblast growth factor (bFGF) and angiopoietin 1 and 2 (ANG-1, ANG-2) with the ELISA method. The protein abundance of angiogenesis-related factor receptors, VEGF receptors 1-3 (VEGFR1-3), FGF receptors 1 and 2 (FGFR1-2) and ANG receptor (TIE2) was evaluated with the Western blot (WB) method. We also analysed the influence of chemerin on the phosphorylation of AMPK using WB.

KEY RESULTS

We found that in the studied endometrial samples, chemerin up-regulated the secretion of VEGF-A, VEGF-B and PlGF, and protein expression of VEGFR3. The adipokine caused a decrease in VEGF-C, VEGF-D and ANG-1 release. Chemerin effect on bFGF and ANG-2 secretion, and protein content of VEGFR1, VEGFR2, FGFR1, FGFR2 and TIE2 were dependent on the stage of pregnancy. Chemerin was found to down-regulate AMPK phosphorylation.

CONCLUSIONS

The obtained in vitro results suggest that chemerin could be an important factor in the early pregnant uterus by its influence on angiogenic factors' secretion and signalling.

IMPLICATIONS

The obtained results on the role of chemerin in the process of endometrial angiogenesis may, in the long term perspective, contribute to the elaboration of more effective methods of modifying reproductive processes and maintaining energy homeostasis in farm animals.

Trophoblast Differentiation: Mechanisms and Implications for Pregnancy Complications

Placental development is a tightly controlled event, in which cell expansion from the trophectoderm occurs in a spatiotemporal manner. Proper trophoblast differentiation is crucial to the vitality of this gestational organ. Obstructions to its development can lead to pregnancy complications, such as preeclampsia, fetal growth restriction, and preterm birth, posing severe health risks to both the mother and offspring. Currently, the only known treatment strategy for these complications is delivery, making it an important area of research. The aim of this review was to summarize the known information on the development and mechanistic regulation of trophoblast differentiation and highlight the similarities in these processes between the human and mouse placenta. Additionally, the known biomarkers for each cell type were compiled to aid in the analysis of sequencing technologies.

Novel insights into conceptus-maternal signaling during pregnancy establishment in pigs

Pregnancy establishment in mammals, including pigs, requires coordinated communication between developing conceptuses (embryos with associated membranes) and the maternal organism. Porcine conceptuses signalize their presence by secreting multiple factors, of which estradiol-17β (E2) is considered the major embryonic signal initiating the maternal recognition of pregnancy. During this time, a limited supply of prostaglandin (PGF2α) to the corpora lutea and an increased secretion of luteoprotective factors (e.g., E2 and prostaglandin E2 [PGE2]) lead to the corpus luteum's maintained function of secreting progesterone, which in turn primes the uterus for implantation. Further, embryo implantation is related to establishing an appropriate proinflammatory environment coordinated by the secretion of proinflammatory mediators including cytokines, growth factors, and lipid mediators of both endometrial and conceptus origin. The novel, dual role of PGF2α has been underlined. Recent studies involving high-throughput technologies and sophisticated experimental models identified a number of novel factors and revealed complex relationships between these factors and those already established. Hence, it seems that early pregnancy should be regarded as a sequence of processes orchestrated by pleiotropic factors that are involved in redundancy and compensatory mechanisms that preserve the essential functions critical for implantation and placenta formation. Therefore, establishing the hierarchy between all molecules present at the embryo-maternal interface is now even more challenging.

Mechanisms regulating the initiation of porcine conceptus elongation

Significant increases in litter size within commercial swine production over the past decades have led to increases in preweaning piglet mortality due to increase within-litter birthweight variation, typically due to mortality of the smallest littermate piglets. Therefore, identifying mechanisms to reduce variation in placental development and subsequent fetal growth are critical to normalizing birthweight variation and improving piglet survivability in high-producing commercial pigs. A major contributing factor to induction of within-litter variation occurs during the peri-implantation period as the pig blastocyst elongates from spherical to filamentous morphology in a short period of time and rapidly begins superficial implantation. During this period, there is significant within-litter variation in the timing and extent of elongation among littermates. As a result, delays and deficiencies in conceptus elongation not only contribute directly to early embryonic mortality, but also influence subsequent within-litter birthweight variation. This study will highlight key aspects of conceptus elongation and provide some recent evidence pertaining to specific mechanisms from -omics studies (i.e., metabolomics of the uterine environment and transcriptomics of the conceptus) that may specifically regulate the initiation of conceptus elongation to identify potential factors to reduce within-litter variation and improve piglet survivability.

Genome‑wide identification, organization, and expression profiles of the chicken fibroblast growth factor genes in public databases and Vietnamese indigenous Ri chickens against highly pathogenic avian influenza H5N1 virus infection

OBJECTIVE

Fibroblast growth factors (FGFs) play critical roles in embryo development, and immune responses to infectious diseases. In this study, to investigate the roles of FGFs, we performed genome-wide identification, expression, and functional analyses of FGF family members in chickens.

METHODS

Chicken FGFs genes were identified and analyzed by using bioinformatics approach. Expression profiles and Hierarchical cluster analysis of the FGFs genes in different chicken tissues were obtained from the genome-wide RNA-seq.

RESULTS

A total of 20 FGF genes were identified in the chicken genome, which were classified into seven distinct groups (A-F) in the phylogenetic tree. Gene structure analysis revealed that members of the same clade had the same or similar exon-intron structure. Chromosome mapping suggested that FGF genes were widely dispersed across the chicken genome and were located on chromosomes 1, 4-6, 9-10, 13, 15, 28, and Z. In addition, the interactions among FGF proteins and between FGFs and mitogen‑activated protein kinase (MAPK) proteins are limited, indicating that the remaining functions of FGF proteins should be further investigated in chickens. Kyoto encyclopedia of genes and genomes pathway analysis showed that FGF gene interacts with MAPK genes and are involved in stimulating signaling pathway and regulating immune responses. Furthermore, this study identified 15 differentially expressed genes (DEG) in 21 different growth stages during early chicken embryo development. RNA-sequencing data identified the DEG of FGFs on 1- and 3-days post infection in two indigenous Ri chicken lines infected with the highly pathogenic avian influenza virus H5N1 (HPAIV). Finally, all the genes examined through quantitative real-time polymerase chain reaction and RNA-Seq analyses showed similar responses to HPAIV infection in indigenous Ri chicken lines (R2 = 0.92- 0.95, p<0.01).

CONCLUSION

This study provides significant insights into the potential functions of FGFs in chickens, including the regulation of MAPK signaling pathways and the immune response of chickens to HPAIV infections.

Novel Muscle-Homing Peptide FGF1 Conjugate Based on AlphaFold for Type 2 Diabetes Mellitus

Drugs for metabolic diseases usually require systemic administration and act on multiple tissues, which may produce some unpredictable side effects. There have been many successful studies on targeted drugs, especially antitumor drugs. However, there is still little research on metabolic disease drugs targeting specific tissues. Fibroblast growth factor 1 (FGF1) is a potential therapy for type 2 diabetes (T2D) without the risk of hypoglycemia. However, the major impediment to the clinical application of FGF1 is its mitogenic potential. We previously engineered an FGF1 variant (named FGF1^ΔHBS) to tune down its mitogenic activity via reducing the heparin-binding ability. However, other notable side effects still remained, including severe appetite inhibition, pathogenic loss of body weight, and increase in fatality rate. In this study, we used AlphaFold2 and PyMOL visualization tools to construct a novel FGF1^ΔHBS conjugate fused with skeletal muscle-targeted (MT) peptide through a flexible peptide linker termed MT-FGF1^ΔHBS. We found that MT-FGF1^ΔHBS specifically homed to skeletal muscle tissue after systemic administration and induced a potent glucose-lowering effect in T2D mice without hypoglycemia. Mechanistically, MT-FGF1^ΔHBS elicits the glucose-lowering effect via AMPK activation to promote the GLUT4 expression and translocation in skeletal muscle cells. Notably, compared with native FGF1^ΔHBS, MT-FGF1^ΔHBS had minimal effects on food intake and body weight and did not induce any hyperplasia in major tissues of both T2D and normal mice, indicating that this muscle-homing protein may be a promising candidate for T2D treatment. Our targeted peptide strategy based on computer-aided structure prediction in this study could be effectively applied for delivering agents to functional tissues to treat metabolic or other diseases, offering enhanced efficacy and reducing systemic off-target side effects.

Zearalenone induces apoptosis and autophagy by regulating endoplasmic reticulum stress signalling in porcine trophectoderm cells

Zearalenone (ZEA), a mycotoxin produced mainly by fungi belonging to Fusarium species in foods and feeds, causes a serious hazard to humans and animals. Numerous studies have revealed that ingesting ZEA can disrupt the reproductive function and impair the reproductive process in animals. This experiment was to investigate the toxicological effect and the mechanism of ZEA exposure on reproduction in pigs during early stages of pregnancy. In the present study, we treated with 0 to 80 μmol/L ZEA for 12 or 24 h in trophoblast ectoderm (pTr) cells. The results showed that ZEA had significantly decreased cell proliferation (P < 0.05), which was accompanied by DNA damage-related cell cycle arrest at G2/M phase, activation of the apoptosis and endoplasmic reticulum (ER) stress, as well as impairment of barrier function (P < 0.05). Western blot analysis and transmission electron microscopy (TEM) showed that exposure to ZEA can activation of autophagy in pTr cells. Importantly, pretreatment with chloroquine (CQ) or 3-methyladenine (3-MA) led to increased apoptosis in pTr cells. Interestingly, pTr cells pretreated with 4-phenylbutyric acid (4-PBA), an inhibitor of ER stress, resulted in reduced cell death in pTr cells, indicating a critical role for ER stress in the activation of autophagy. In conclusion, these results reveal that ZEA-triggered ER stress is critical for the cell fate decision of pTr cells during early porcine embryonic development. Application of small molecules with ability of blocking ER stress might be therapeutic option to reduce the deleterious effect of ZEA in pregnant animals.

L-Tryptophan activates the aryl hydrocarbon receptor and induces cell cycle arrest in porcine trophectoderm cells

During implantation, the proliferation of trophectoderm cells (the outer epithelium of blastocysts) is related to conceptus elongation and placenta formation. Tryptophan (Trp) is a key regulator of embryogenesis and embryonic implantation during pregnancy. We sought to determine whether different concentrations of Trp alters porcine trophectoderm (pTr) cell proliferation. pTr cells were cultured in medium containing 40, 500, or 1000 μM Trp. The cell proliferation rate and the progression of the cells through the cell cycle were determined. To identify differentially expressed genes (DEGs) in the pTr cells, we compared mRNA transcriptomes by RNA-Seq after cell treatment with different concentrations of Trp. Some candidate DEGs were identified by quantitative reverse transcription PCR (qPCR). High L-Trp levels (500 and 1000 μM) inhibited cell proliferation and induced cell cycle arrest. We identified 19 DEGs between the 500 μM L-Trp and 40 μM L-Trp groups and 168 DEGs between the 1000 μM L-Trp and 40 μM L-Trp groups and subsequently used qPCR to validate some genes that were upregulated or downregulated. The functional gene networks in which the DEGs were most enriched included those associated with regulating DNA replication and the cell cycle, and the majority of the DEGs in both of these functional pathways was downregulated. The results showed that the addition of 500 and 1000 μM Trp significantly increased the abundance of proteins in the Aryl Hydrocarbon Receptor (AHR) signaling pathway. Collectively, these results indicate a novel and important role for Trp in mediating the proliferation of porcine placental cells largely via the AHR signaling pathway. Additionally, these findings help to explain the side effects of excessive Trp supplementation on placenta development and embryo growth in mammals.

FGF signaling directs myotube guidance by regulating Rac activity

Nascent myotubes undergo a dramatic morphological transformation during myogenesis, in which the myotubes elongate over several cell diameters and are directed to the correct muscle attachment sites. Although this process of myotube guidance is essential to pattern the musculoskeletal system, the mechanisms that control myotube guidance remain poorly understood. Using transcriptomics, we found that components of the Fibroblast Growth Factor (FGF) signaling pathway were enriched in nascent myotubes in Drosophila embryos. Null mutations in the FGF receptor heartless (htl), or its ligands, caused significant myotube guidance defects. The FGF ligand Pyramus is expressed broadly in the ectoderm, and ectopic Pyramus expression disrupted muscle patterning. Mechanistically, Htl regulates the activity of Rho/Rac GTPases in nascent myotubes and effects changes in the actin cytoskeleton. FGF signals are thus essential regulators of myotube guidance that act through cytoskeletal regulatory proteins to pattern the musculoskeletal system.

Inactivation of porcine interleukin-1β results in failure of rapid conceptus elongation

Conceptus expansion throughout the uterus of mammalian species with a noninvasive epitheliochorial type of placentation is critical establishing an adequate uterine surface area for nutrient support during gestation. Pig conceptuses undergo a unique rapid morphological transformation to elongate into filamentous threads within 1 h, which provides the uterine surface to support development and maintain functional corpora lutea through the production of estrogen. Conceptus production of a unique interleukin 1β, IL1B2, temporally increases during the period of trophoblast remodeling during elongation. CRISPR/Cas9 gene editing was used to knock out pig conceptus IL1B2 expression and the secretion of IL1B2 during the time of conceptus elongation. Trophoblast elongation occurred on day 14 in wild-type (IL1B2+/+) conceptuses but did not occur in ILB2-null (IL1B2-/-) conceptuses. Although the morphological transition of IL1B2-/- conceptuses was inhibited, expression of a number of conceptus developmental genes was not altered. However, conceptus aromatase expression and estrogen secretion were decreased, indicating that IL1B2 may be involved in the spatiotemporal increase in conceptus estrogen synthesis needed for the establishment of pregnancy in the pig and may serve to regulate the proinflammatory response of endometrium to IL1B2 during conceptus elongation and attachment to the uterine surface.

Suppression of ERK signalling abolishes primitive endoderm formation but does not promote pluripotency in rabbit embryo

Formation of epiblast (EPI) – the founder line of all embryonic lineages – and extra-embryonic supportive tissues is one of the key events in mammalian development. The prevailing model of early mammalian development is based almost exclusively on the mouse. Here, we provide a comprehensive, stage-by-stage analysis of EPI and extra-embryonic primitive endoderm (PrE) formation during preimplantation development of the rabbit. Although we observed that rabbit embryos have several features in common with mouse embryos, including a stage-related initiation of lineage specification, our results demonstrate the existence of some key differences in lineage specification among mammals. Contrary to the current view, our data suggest that reciprocal repression of GATA6 and NANOG is not fundamental for the initial stages of PrE versus EPI specification in mammals. Furthermore, our results provide insight into the observed discrepancies relating to the role of FGF/ERK signalling in PrE versus EPI specification between mouse and other mammals.

Highlighted Article: A comprehensive analysis of rabbit preimplantation development reveals key differences between rabbit and mouse, with some aspects of lineage specification in rabbit more closely resembling that of human and primate embryos.

Preattachment Embryos of Domestic Animals: Insights into Development and Paracrine Secretions

In mammalian species, endometrial receptivity is driven by maternal factors independently of embryo signals. When pregnancy initiates, paracrine secretions of the preattachment embryo are essential both for maternal recognition and endometrium preparation for implantation and for coordinating development of embryonic and extraembryonic tissues of the conceptus. This review mainly focuses on domestic large animal species. We first illustrate the major steps of preattachment embryo development, including elongation in bovine, ovine, porcine, and equine species. We next highlight conceptus secretions that are involved in the communication between extraembryonic and embryonic tissues, as well as between the conceptus and the endometrium. Finally, we introduce experimental data demonstrating the intimate connection between conceptus secretions and endometrial activity and how adverse events perturbing this interplay may affect the progression of implantation that will subsequently impact pregnancy outcome, postnatal health, and expression of production traits in livestock offspring.

The oncoprotein HBXIP up-regulates FGF4 through activating transcriptional factor Sp1 to promote the migration of breast cancer cells

We have reported that the oncoprotein hepatitis B X-interacting protein (HBXIP) is able to promote migration of breast cancer cells. Fibroblast growth factor 4 (FGF4) is a multipotent growth factor and is highly expressed in various human cancers. However, the regulatory mechanism of FGF4 in breast cancer remains poorly understood. In the present study, we report that HBXIP is able to up-regulate FGF4 to enhance the migration of breast cancer cells. Immunohistochemistry staining showed that HBXIP and FGF4 were highly expressed in clinical metastatic lymph nodes of breast tumor. The expression levels of HBXIP were positively related to those of FGF4 in clinical breast cancer tissues. Then, we validated that HBXIP up-regulated the expression of FGF4 at the levels of promoter, mRNA and protein by luciferase reporter gene assays, reverse transcription-polymerase chain reaction and Western blot analysis. Moreover, we found that HBXIP was able to activate FGF4 promoter through transcriptional factor Sp1 by luciferase reporter gene assays. Chromatin immunoprecipitation assays confirmed that HBXIP coactivated Sp1 to stimulate FGF4 promoter. In function, we showed that HBXIP promoted breast cancer cell migration through FGF4 by wound healing and transwell cell migration assays. Thus, we conclude that the oncoprotein HBXIP up-regulates FGF4 through activating transcriptional factor Sp1 to promote the migration of breast cancer cells. Therapeutically, HBXIP may serve as a novel target in breast cancer.