Novel Elongator Protein 2 Inhibitors Mitigating Tumor Necrosis Factor-α Induced Osteogenic Differentiation Inhibition

Obesity and lipid metabolism in the development of osteoporosis (Review)

Osteoporosis is a common bone metabolic disease that causes a heavy social burden and seriously threatens life. Improving osteogenic capacity is necessary to correct bone mass loss in the treatment of osteoporosis. Osteoblasts are derived from the differentiation of bone marrow mesenchymal stem cells, a process that opposes adipogenic differentiation. The peroxisome proliferator‑activated receptor γ and Wnt/β‑catenin signaling pathways mediate the mutual regulation of osteogenesis and adipogenesis. Lipid substances play an important role in the occurrence and development of osteoporosis. The content and proportion of lipids modulate the activity of immunocytes, mainly macrophages, and the secretion of inflammatory factors, such as IL‑1, IL‑6 and TNF‑α. These inflammatory effectors increase the activity and promote the differentiation of osteoclasts, which leads to bone imbalance and stronger bone resorption. Obesity also decreases the activity of antioxidases and leads to oxidative stress, thereby inhibiting osteogenesis. The present review starts by examining the bidirectional differentiation of BM‑MSCs, describes in detail the mechanism by which lipids affect bone metabolism, and discusses the regulatory role of inflammation and oxidative stress in this process. The review concludes that a reasonable adjustment of the content and proportion of lipids, and the alleviation of inflammatory storms and oxidative damage induced by lipid imbalances, will improve bone mass and treat osteoporosis.

ELP2-NLRP3-GSDMD/GSDME-mediated pyroptosis is induced by TNF-α in MC3T3-E1 cells during osteogenic differentiation

Tumour necrosis factor-α (TNF-α) is a cytokine involved in systemic inflammation. TNF-α slows down osteogenic differentiation, which may contribute to poor bone development in the inflammatory microenvironment. TNF-α inhibits osteogenic differentiation by activating the JAK-STAT3 pathway, of which Signal transducer and activator of transcription 3 (STAT3)-interacting protein 1 (StIP1, also known as elongator complex protein 2, ELP2) is a key protein in the JAK-STAT3 pathway. We investigated whether and how ELP2 activation mediates the TNF-α-induced pyroptosis during osteoblastic differentiation. Using in vitro cell cultures of preosteoblastic MC3T3-E1 cells, we found that TNF-α exposure causes cell pyroptosis in an inflammatory microenvironment during osteoblastic differentiation. Bioinformatics, protein docking model and co-immunoprecipitation analysis revealed an association between ELP2, STAT3 and NLRP3. Forced ELP2 expression promoted MC3T3-E1 cells pyroptosis, with an increase in the expression of STAT3, NLRP3 inflammasome, GSDMD/GSDME, osteoblast marker genes, and the activity of alkaline phosphatase. In contrast, ELP2 silencing ameliorated MC3T3-E1 cells pyroptosis, and osteogenic differentiation, especially after TNF-α stimulation. The TNF-α-induced cells pyroptosis during osteoblastic differentiation was therefore mediated by ELP2. These results suggest that ELP2 is upregulated at the pyroptosis of MC3T3-E1 cells and inhibits osteogenic differentiation in response to TNF-α through NLRP3-GSDMD/GSDME activation.

Parentage testing and looking for single nucleotide markers associated with antler quality in deer (Cervus elaphus)

To provide a cost-efficient parentage testing kit for red deer (Cervus elaphus), a 63 SNP set has been developed from a high-density Illumina BovineHD BeadChip containing 777 962 SNPs after filtering of genotypes of 50 stags. The successful genotyping rate was 38.6 % on the chip. The ratio of polymorphic loci among effectively genotyped loci was 6.5 %. The selected 63 SNPs have been applied to 960 animals to perform parentage control. Thirty SNPs out of the 63 had worked on the OpenArray platform. Their combined value of the probability of identity and exclusion probability was 4.9×10-11 and 0.99803, respectively.

A search for loci linked with antler quality was also performed on the genotypes of the above-mentioned stags. Association studies revealed 14 SNPs associated with antler quality, where low-quality antlers with short and thin main beam antlers had values from 1 to 2, while high-quality antlers with long and strong main beams had values between 4 and 5. The chance for a stag to be correctly identified as having high-value antlers is expected to be over 88 %.