Phorbol 12-myristate 13-acetate (PMA) suppresses high Ca2+-enhanced adipogenesis in bone marrow stromal cells

Lanthanum nitrate inhibits adipogenesis in 3T3-L1 preadipocytes with a disorder of mitotic clonal expansion process

Lanthanum (La) as a rare earth element is widely used in agriculture, industry, and medicine. It has been suggested in several studies that La might influence glycolipid metabolism in vivo. In this study, we used 3T3-L1 preadipocytes as in vitro cell model to elucidate the effects of La(NO₃ )₃ on adipogenesis and the underlying mechanisms. The results showed that La(NO₃ )₃ could inhibit the adipogenic differentiation of 3T3-L1 preadipocytes, which showed a decrease in lipid accumulation and the downregulation of specific adipogenic transcription factors. La(NO₃ )₃ exerted its inhibitory effect mainly at the early differentiation stage. Furthermore, La(NO₃ )₃ influenced the S-phase entry and cell cycle process during the mitotic clonal expansion and regulated the phosphorylation of signal transducer and activator of transcription 3 (STAT3) and expressions of the proteins in phosphatidylinositol 3-kinase (PI3K)/Akt pathway at the early stage of differentiation. Besides, La(NO₃ )₃ upregulated the expressions of wnt10b mRNA and β-catenin protein and promoted the nucleus translocation of β-catenin. Additionally, we found that La(NO₃ )₃ could promote the growth of 3T3-L1 preadipocytes both with and without MDI (3-isobutyl-1-methylxanthine [IBMX], dexamethasone [Dex], and insulin) stimulation. Collectively, these results indicated that La(NO₃ )₃ could inhibit adipogenesis in 3T3-L1 preadipocytes and influence cell proliferation.

Metabolomic biomarkers of low BMD: a systematic review

Due to the metabolic nature of osteoporosis, this study was conducted to identify metabolomic studies investigating the metabolic profile of low bone mineral density (BMD) and osteoporosis. A comprehensive systematic literature search was conducted through PubMed, Web of Science, Scopus, and Embase databases up to April 08, 2020, to identify observational studies with cross-sectional or case-control designs investigating the metabolic profile of low BMD in adults using biofluid specimen via metabolomic platform. The quality assessment panel specified for the "omics"-based diagnostic research (QUADOMICS) tool was used to estimate the methodologic quality of the included studies. Ten untargeted and one targeted approach metabolomic studies investigating biomarkers in different biofluids through mass spectrometry or nuclear magnetic resonance platforms were included in the systematic review. Some metabolite panels, rather than individual metabolites, showed promising results in differentiating low BMD from normal. Candidate metabolites were of different categories including amino acids, followed by lipids and carbohydrates. Besides, certain pathways were suggested by some of the studies to be involved. This systematic review suggested that metabolic profiling could improve the diagnosis of low BMD. Despite valuable findings attained from each of these studies, there was great heterogeneity regarding the ethnicity and age of participants, samples, and the metabolomic platform. Further longitudinal studies are needed to validate the results and confirm the predictive role of metabolic profile on low BMD and fracture. It is also mandatory to address and minimize the heterogeneity in future studies by using reliable quantitative methods. Summary: Due to the metabolic nature of osteoporosis, researchers have considered metabolomic studies recently. This systematic review showed that metabolic profiling including different categories of metabolites could improve the diagnosis of low BMD. However, great heterogeneity was observed and it is mandatory to address and minimize the heterogeneity in future studies.

Cross talk between 26S proteasome and mitochondria in human mesenchymal stem cells' ability to survive under hypoxia stress

Mesenchymal stem cells (MSCs) are regarded as unique cells which play an imperative role in the field of regenerative medicine. They are characterized by the self-renewal capacity, multi-lineage differentiation abilities and immunomodulation properties which render them perfectly ideal cell type for treating a wide range of chronic diseases. Despite these enchanted features, there are many hurdles that need to be circumvented to ensure their long-term survival and viability after transplantation. Recently, hypoxia has been indicated as one of the most baffling stress conditions that can affect the survival rate of MSCs either positively or negatively depending on the level of hypoxia. MSCs can survive well under moderate hypoxia, but die shortly if they were exposed to severe hypoxia without clearly convincing explanation for this enigma. The current study reveals a novel mechanism of 26S proteasome in controlling the ability of BM-MSCs to withstand hypoxic stress by maintaining proper mitochondrial function. The results indicated that 26S proteasome remains functioning once BM- MSCs are exposed to moderate hypoxia (2.5%O2) and preserves their survival and proliferation mediated by intact mitochondrial performance, whereas 26S proteasome becomes inactive when BM-MSCs faces severe hypoxia that lead to poor mitochondrial function and less chance to survive longer. The outcomes of this study demonstrated the importance of 26S proteasome machinery in enhancing the resistance of BM-MSCs to hypoxic stress condition which may help in better planning future studies that target this system. Schematic representation summarizing the findings of the current study. 26S proteasome function preservation in normoxia and moderate hypoxia leads to maintain appropriate proliferation and mitochondrial activity in human BM-MSCs and promote their survival. On the opposite side, severe hypoxia disrupts the 26S proteasome function leading to significant reduction in the proliferation, survival and mitochondrial dynamics in human BM-MSCs causing their death.