MicroRNA-210 Regulates Endoplasmic Reticulum Stress and Apoptosis in Porcine Embryos

Overexpression of miR-192 Inhibits In Vitro Porcine Embryo Development by Inducing Oxidative Stress Damage and Impairing Mitochondrial Function

Early embryonic development relies on intricately regulated gene expression, and miRNAs influence zygotic genome activation (ZGA), cleavage, and cell fate determination through post-transcriptional regulatory mechanisms. miR-192 is expressed in early pig embryos and participates in various reproductive processes. However, its role in pre-implantation pig embryo development remains poorly understood. In this study, we microinjected the miR-192 agonist (miR-192 agomir) into parthenogenetically activated pig embryos to evaluate its effects on early pig embryo development. Our findings indicate that compared to the control group (agomir NC), miR-192 agomir impairs the developmental capacity of parthenogenetic pig embryos to reach the 2-cell, 4-cell, and blastocyst stages. This impairment leads to imbalances in the oxidative-reductive system and abnormalities in mitochondrial function during the 4-cell stage, resulting in the significant accumulation of ROS, notable decreases in the expression of antioxidant enzymes CAT and SOD1 mRNA, reduction in mitochondrial membrane potential, and induction of apoptosis in pig blastocysts. Additionally, the overexpression of miR-192 inhibits the expression of its target genes YY1 and the pluripotency factor NANOG mRNA. In conclusion, this study reveals that the overexpression of miR-192 adversely affects early pig embryo development, providing new evidence for understanding the role miR-192 plays in reproduction.

Oviductal extracellular vesicles miRNA cargo varies in response to embryos and their quality

BACKGROUND

Increasing evidence points to an active role of oviductal extracellular vesicles (oEVs) in the early embryo-maternal dialogue. However, it remains unclear whether oEVs contribute to the recognition of the presence of embryos and their quality in the oviduct. Hence, we examined whether the molecular cargo of oEVs secreted by bovine oviduct epithelial cells (BOEC) differs depending on the presence of good (≥ 8 cells, G) or poor (< 8 cells, P) quality embryos. In addition, differences in RNA profiles between G and P embryos were analyzed in attempt to distinguish oEVs and embryonic EVs cargos.

METHODS

For this purpose, primary BOEC were co-cultured with in vitro produced embryos (IVP) 53 h post fertilization as follows: BOEC with G embryos (BGE); BOEC with P embryos (BPE); G embryos alone (GE); P embryos alone (PE); BOEC alone (B) and medium control (M). After 24 h of co-culture, conditioned media were collected from all groups and EVs were isolated and characterized. MicroRNA profiling of EVs and embryos was performed by small RNA-sequencing.

RESULTS

In EVs, 84 miRNAs were identified, with 8 differentially abundant (DA) miRNAs for BGE vs. B and 4 for BPE vs. B (P-value < 0.01). In embryos, 187 miRNAs were identified, with 12 DA miRNAs for BGE vs. BPE, 3 for G vs. P, 8 for BGE vs. GE, and 11 for BPE vs. PE (P-value < 0.01).

CONCLUSIONS

These results indicated that oEVs are involved in the oviductal-embryo recognition and pointed to specific miRNAs with signaling and supporting roles during early embryo development.

Effects of klotho protein or klotho knockdown in porcine oocytes at different stages

Klotho is a protein that plays different functions in female fertility. We have previously reported that klotho protein supplementation during in vitro maturation improves porcine embryo development, while klotho knockout for somatic cell cloning completely blocks full-term pregnancy in vivo. However, the effects of the microinjection of klotho protein or klotho knockdown dual vector in porcine embryos at different time points and the specific molecular mechanisms remain largely unknown. In this study, we injected the preassembled cas9 + sgRNA dual vector, for klotho knockdown, into the cytoplasm of the germinal vesicle stage of oocytes and into porcine embryos after 6-h parthenogenetic activation. Similarly, the klotho protein was inserted into the cytoplasm of germinal vesicle stage oocytes and porcine embryos after 6-h parthenogenetic activation. Compared with the controls, the microinjection of klotho dual vector markedly decreased the blastocyst formation rates in germinal vesicle stage oocytes and activated embryos. However, the efficiency of blastocyst formation when klotho protein was inserted before in vitro maturation was significantly higher than that after klotho protein insertion into parthenogenetically activated embryos. These results indicated that klotho knockdown may impair embryo development into blastocyst irrespective of injection timing. In addition, klotho protein injection timing in pig embryos may be an important factor for regulating embryo development.

The Improvement of Porcine In Vitro Embryo Development through Regulating Autophagy by miRNA-143 Inhibition

In vitro embryo research is an important stage for the advancement of many reproductive technologies in research and agriculture. For this reason, the improvement of in vitro embryo development is a strategic field worthy of investigation. Relatively little is known about miR-143 and its effects on autophagy associated with embryo development and in vitro embryo culture. In this study, we examined the effect of miR-143 (via mimics and inhibitors) on embryonic development threatened by microinjection after parthenogenetic activation. We evaluated rates of cleavage, blastocyst, and total cell number of blastocyst; additionally, we performed LC3 immunofluorescence analysis and mRNA expression analyses of genes associated with autophagy, endoplasmic reticulum (ER)-phagy, ER stress, embryo quality, and apoptosis. The inhibition of miR-143 positively influenced embryo development by increasing the activity of autophagy and ER-phagy and the expression of embryo quality-related genes, while reducing apoptosis. In contrast, treatment with miR-143 mimics increased ER stress-related gene expression and apoptosis, and reduced embryo development. Together, our findings indicate that miR-143 plays a role in the interplay between autophagy, ER-phagy, and embryo quality during early porcine embryo development.

Porcine epidemic diarrhea virus infection induces endoplasmic reticulum stress and unfolded protein response in jejunal epithelial cells of weaned pigs

Porcine epidemic diarrhea virus (PEDV) infection leads to diarrhea and subsequently to decreased feed efficiency and growth in weaned pigs. Given that few studies have addressed the host-virus interaction in vivo, this study focused on endoplasmic reticulum (ER) stress and unfolded protein response (UPR) in jejunal epithelial cells during PEDV infection. Eight-week-old pigs (n = 64) were orally inoculated with PEDV IN19338 strain (n = 40) or sham-inoculated (n = 24) and analyzed for PEDV viral RNA shedding using reverse transcription-quantitative polymerase chain reaction and for viral antigen within enterocytes using immunohistochemistry (IHC). ER stress was analyzed in a subset of 9 PEDV-inoculated pigs with diarrhea, detectable viral RNA, and viral antigen (PEDV-immunopositive pigs). Compared with control pigs, PEDV-immunopositive pigs had a reduced ratio of villus height to crypt depth in the jejunum (P = .002, n = 9 per group), consistent with intestinal injury. The protein levels of ATF6, IRE1, PERK, XBP1u, ATF4, GRP78, and caspase-3 were assessed in jejunal epithelial cells at the villus tips via IHC. Both ER stress and UPR were demonstrated in PEDV-immunopositive pigs by the increased expression of ATF6 (P = .047), IRE1 (P = .007), and ATF4 (P = .001). The expression of GRP78 (P = .024) and caspase-3 (P = .004) were also increased, indicating an accompanying increase in ER protein folding capacity and apoptosis. Overall, these results reveal that PEDV infection induces ER stress and UPR in intestinal epithelial cells of weaned pigs.