Autophagy of granulosa cells (GCs) is involved in follicular atresia, which occurs repeatedly during the ovarian development cycle. Several circadian clock genes are rhythmically expressed in both rodent ovarian tissues and GCs. Nuclear receptor subfamily 1 group D member 1 (NR1D1), an important component of the circadian clock system, is involved in the autophagy process through the regulation of autophagy-related genes. However, there are no reports illustrating the role of the circadian clock system in mouse GC autophagy. In the present study, we found that core circadian clock genes (Bmal1, Per2, Nr1d1, and Dbp) and an autophagy-related gene (Atg5) exhibited rhythmic expression patterns across 24 h in mouse ovaries and primary GCs. Treatment with SR9009, an agonist of NR1D1, significantly reduced the expression of Bmal1, Per2, and Dbp in mouse GCs. ATG5 expression was significantly attenuated by SR9009 treatment in mouse GCs. Conversely, Nr1d1 knockdown increased ATG5 expression in mouse GCs. Decreased NR1D1 expression at both the mRNA and protein levels was detected in the ovaries of Bmal1-/- mice, along with elevated expression of ATG5. Dual-luciferase reporter assay and electrophoretic mobility shift assay showed that NR1D1 inhibited Atg5 transcription by binding to two putative retinoic acid-related orphan receptor response elements within the promoter. In addition, rapamycin-induced autophagy and ATG5 expression were partially reversed by SR9009 treatment in mouse GCs. Taken together, our current data demonstrated that the circadian clock regulates GC autophagy through NR1D1-mediated inhibition of ATG5 expression, and thus, plays a role in maintaining autophagy homeostasis in GCs.
Background Cell-based tissue engineering represents a promising management for meniscus repair and regeneration. The present study aimed to investigate whether the injection of parathyroid hormone (PTH) (1-34) could promote the regeneration and chondroprotection of 3D printed scaffold seeded with bone marrow mesenchymal stem cells (BMSCs) in a canine total meniscal meniscectomy model. Methods 3D printed poly(e-caprolactone) scaffold seeded with BMSCs was cultured in vitro, and the effects of in vitro culture time on cell growth and matrix synthesis of the BMSCs–scaffold construct were evaluated by microscopic observation and cartilage matrix content detection at 7, 14, 21, and 28 days. After that, the tissue-engineered meniscus based on BMSCs–scaffold cultured for the appropriate culture time was selected for in vivo implantation. Sixteen dogs were randomly divided into four groups: PTH + BMSCs–scaffold, BMSCs–scaffold, total meniscectomy, and sham operation. The regeneration of the implanted tissue and the degeneration of articular cartilage were assessed by gross, histological, and immunohistochemical analysis at 12 weeks postoperatively. Results In vitro study showed that the glycosaminoglycan (GAG)/DNA ratio and the expression of collagen type II (Col2) were significantly higher on day 21 as compared to the other time points. In vivo study showed that, compared with the BMSCs–scaffold group, the PTH + BMSCs–scaffold group showed better regeneration of the implanted tissue and greater similarity to native meniscus concerning gross appearance, cell composition, and cartilage extracellular matrix deposition. This group also showed less expression of terminal differentiation markers of BMSC chondrogenesis as well as lower cartilage degeneration with less damage on the knee cartilage surface, higher expression of Col2, and lower expression of degeneration markers. Conclusions Our results demonstrated that PTH (1-34) promotes the regenerative and chondroprotective effects of the BMSCs–3D printed meniscal scaffold in a canine model, and thus, their combination could be a promising strategy for meniscus tissue engineering.
Long noncoding RNAs (lncRNAs) have been extensively explored over the past decade, including mice and humans. However, their impact on the transdifferentiation of canine bone marrow mesenchymal stem cells (cBMSCs) into insulin-producing cells (IPCs) is largely unknown. In this study, we used a three-step induction procedure to induce cBMSCs into IPCs, and samples (two biological replicates each) were obtained after each step; the samples consisted of “BMSCs” (B), “stage 1” (S1), “stage 2” (S2), “stage 3” (S3), and “islets” (I). After sequencing, 15,091 lncRNAs were identified, and we screened 110, 41, 23, and 686 differentially expressed lncRNAs (padjusted < 0.05) in B vs. S1, S1 vs. S2, S2 vs. S3, and I vs. S3 pairwise comparisons, respectively. In lncRNA target prediction, there were 166,623 colocalized targets and 2,976,362 correlated targets. Gene Ontology (GO) analysis showed that binding represented the main molecular functions of both the cis- and trans-modes. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis suggested that the insulin signaling pathway, Rap1 signaling pathway, tight junctions, MAPK signaling pathway, and cell cycle were enriched for these relative genes. The expression of lncRNAs was verified using qRT-PCR. This study provides a lncRNA catalog for future research concerning the mechanism of the transdifferentiation of cBMSCs into IPCs.
The circadian clock system is based on interlocked positive and negative transcriptional and translational feedback loops of core clock genes and their encoded proteins. The mammalian circadian clock system has been extensively investigated using mouse models, but has been poorly investigated in diurnal ruminants. In this study, goat embryonic fibroblasts (GEFs) were isolated and used as a cell model to elucidate the caprine circadian clock system. Real-time quantitative PCR analysis showed that several clock genes and clock-controlled genes were rhythmically expressed in GEFs over a 24 h period after dexamethasone stimulation. Immunofluorescence revealed that gBMAL1 and gNR1D1 proteins were expressed in GEFs, and western blotting analysis further verified that the proteins were expressed with circadian rhythmic changes. Diurnal changes in clock and clock-controlled gene expression at the mRNA and protein levels were also observed in goat liver and kidney tissues at two representative time points in vivo. Amino acid sequences and tertiary structures of goat BMAL1 and CLOCK proteins were found to be highly homologous to those in mice and humans. In addition, a set of goat representative clock gene orthologs and the promoter regions of two clock genes of goats and mice were cloned. Dual-luciferase reporter assays showed that gRORα could activate the promoter activity of the goat BMAL1, while gNR1D1 repressed it. The elevated pGL4.10-gNR1D1-Promoter-driven luciferase activity induced by mBMAL1/mCLOCK was much higher than that induced by gBMAL1/gCLOCK, and the addition of gCRY2 or mPER2 repressed it. Real-time bioluminescence assays revealed that the transcriptional activity of BMAL1 and NR1D1 in goats and mice exhibited rhythmic changes over a period of approximately 24 h in NIH3T3 cells or GEFs. Notably, the amplitudes of gBMAL1 and gNR1D1 promoter-driven luciferase oscillations in NIH3T3 cells were higher than those in GEFs, while mBMAL1 and mNR1D1 promoter-driven luciferase oscillations in NIH3T3 cells had the highest amplitude. In sum, transcriptional and translational loops of the mammalian circadian clock system were found to be broadly conserved in goats and not as robust as those found in mice, at least in the current experimental models. Further studies are warranted to elucidate the specific molecular mechanisms involved.
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