Aldose reductase regulates microglia/macrophages polarization through the cAMP response element-binding protein after spinal cord injury in mice.

Inflammatory reactions are the most critical pathological processes occurring after spinal cord injury (SCI). Activated microglia/macrophages have either detrimental or beneficial effects on neural regeneration based on their functional polarized M1/M2 subsets. However, the mechanism of microglia/macrophage polarization to M1/M2 at the injured spinal cord environment remains unknown. In this study, wild-type (WT) or aldose reductase (AR)-knockout (KO) mice were subjected to SCI by a spinal crush injury model. The expression pattern of AR, behavior tests for locomotor activity, and lesion size were assessed at between 4 h and 28 days after SCI. We found that the expression of AR is upregulated in microglia/macrophages after SCI in WT mice. In AR KO mice, SCI led to smaller injury lesion areas compared to WT. AR deficiency-induced microglia/macrophages induce the M2 rather than the M1 response and promote locomotion recovery after SCI in mice. In the in vitro experiments, microglia cell lines (N9 or BV2) were treated with the AR inhibitor (ARI) fidarestat. AR inhibition caused 4-hydroxynonenal (HNE) accumulation, which induced the phosphorylation of the cAMP response element-binding protein (CREB) to promote Arg1 expression. KG501, the specific inhibitor of phosphorylated CREB, could cancel the upregulation of Arg1 by ARI or HNE stimulation. Our results suggest that AR works as a switch which can regulate microglia by polarizing cells to either the M1 or the M2 phenotype under M1 stimulation based on its states of activity. We suggest that inhibiting AR may be a promising therapeutic method for SCI in the future

Snx3 Regulates Recycling of the Transferrin Receptor and Iron Assimilation

Sorting of endocytic ligands and receptors is critical for diverse cellular processes. The physiological significance of endosomal sorting proteins in vertebrates, however, remains largely unknown. Here we report that sorting nexin 3 (Snx3) facilitates the recycling of transferrin receptor (Tfrc) and thus is required for the proper delivery of iron to erythroid progenitors. Snx3 is highly expressed in vertebrate hematopoietic tissues. Silencing of Snx3 results in anemia and hemoglobin defects in vertebrates due to impaired transferrin (Tf)-mediated iron uptake and its accumulation in early endosomes. This impaired iron assimilation can be complemented with non-Tf iron chelates. We show that Snx3 and Vps35, a component of the retromer, interact with Tfrc to sort it to the recycling endosomes. Our findings uncover a role of Snx3 in regulating Tfrc recycling, iron homeostasis, and erythropoiesis. Thus, the identification of Snx3 provides a genetic tool for exploring erythropoiesis and disorders of iron metabolism.National Institutes of Health (U.S.) (P01 HL032262

Genome-wide association study identifies loci and candidate genes for non-idiopathic pulmonary hypertension in Eastern Chinese Han population

Abstract Background Pulmonary hypertension (PH) is a rare disease characterized by proliferation and occlusion of small pulmonary arterioles, which has been associated with a high mortality rate. The pathogenesis of PH is complex and incompletely understood, which includes both genetic and environmental factors that alter vascular structure and function. Methods Thus we aimed to reveal the potential genetic etiology of PH by targeting 143 tag SNPs of 14 candidate genes. Totally 208 individuals from Chinese Han population were enrolled in the present study, including 109 non-idiopathic PH patients and 99 healthy controls. Results The data revealed that 2 SNPs were associated with PH overall susceptibility at p < 3×10− 4 after Bonferroni correction. The top hit was rs6557421 (p = 4.5×10− 9), located within Nox3 gene on chromosome 6. Another SNP rs3744439 located in Tbx4 gene, also showed evidence of association with PH susceptibility (p = 1.2×10− 6). The distribution of genotype frequencies of rs6557421 and rs3744439 have dramatic differences between PH patients and controls. Individuals with rs6557421 TT genotype had a 10.72-fold/14.20-fold increased risk to develop PH when compared with GG or GG/GT carriers in codominant or recessive model, respectively (TT versus GG: 95%CI = 4.79–24.00; TT versus GG/GT: 95%CI = 6.65–30.33). As for rs3744439, AG genotype only occurred in healthy controls but has not been observed in PH patients. We further validated the result by using 26 different populations from five regions around the globe, including African (AFR), American (AMR), East Asian (EAS), European (EUR), and South Asian (SAS). In consistent with the present case-control study’s results, significantly different genotype frequencies of the observed SNPs existed between PH patients and healthy individuals from all over the world. Conclusions The results suggested that rs6557421 variant in Nox3 and rs3744439 variant in Tbx4 might have potential effect on individual susceptibility to pulmonary hypertension, which could lead to therapeutic or diagnosis approaches in PH

Differential bone remodeling mechanism in hindlimb unloaded and hibernating Daurian ground squirrels: a comparison between artificial and natural disuse within the same species

International audienceLoss of bone mass can occur in mammals after prolonged disuse but the situation for hibernators that are in a state of torpor for many months of the year is not yet fully understood. The present study assesses the bone remodeling mechanisms present in Daurian ground squirrels (Spermophilus dauricus) during hibernation as compared with a model of hindlimb disuse. Differences in microstructure, mechanical properties, bone remodeling-related proteins (Runx2, OCN, ALP, RANKL, CTK and MMP-9) and key proteins of Wnt/beta-catenin signaling pathway (GSK-3 beta and phospho-beta-catenin) were evaluated in ground squirrels under 3 conditions: summer active (SA) vs. hibernation (HIB) vs. hindlimb unloaded (HLU). The results indicated that the body weight in HLU ground squirrels was lower than the SA group, and the middle tibia diameter in the HLU group was lower than that in SA and HIB groups. The thickness of cortical and trabecular bone in femurs from HLU ground squirrels was lower than in SA and HIB groups. Most parameters of the tibia in the HLU group were lower than those in SA and HIB groups, which indicated cortical bone loss in ground squirrels. Moreover, our data showed that the changes in microscopic parameters in the femur were more obvious than those in the tibia in HLU and HIB ground squirrels. The levels of Runx2 and ALP were lower in HLU ground squirrels than SA and HIB groups. The protein levels of OCN were unchanged in the three groups, but the protein levels of ALP were lower in the HLU group than in SA and HIB groups. RANKL, CTK and MMP-9 protein levels were significantly decreased in tibia of HLU ground squirrels as compared with SA and HIB groups. In addition, the protein expression levels of RANKL, CTK and MMP-9 showed no statistical difference between SA and HIB ground squirrels. Thus, the mechanisms involved in the balance between bone formation and resorption in hibernating and hindlimb unloading ground squirrels may be different. The present study showed that in femur, the Wnt signaling pathway was inhibited, the protein level of GSK-3 beta was increased, and the protein expression of phospho-beta-catenin was decreased in the HIB group as compared with the SA group, which indicates that the Wnt signaling pathway has a great influence on the femur of the HIB group. In conclusion, the natural anti-osteoporosis properties of Daurian ground squirrels are seasonal. The squirrels do not experience bone loss when they are inactive for a long time during hibernation, but the mechanisms of anti-osteoporosis did not work in HLU summer active squirrels

Tree-ring-based precipitation reconstruction for Mt. Xinglong, China, since AD 1679

On the basis of a significant correlation between the ring width of Qinghai spruce (Picea crassifolia Kom.) trees at Mt. Xinglong in north-central China and observed instrumental data, a transfer function was designed and the annual precipitation (from the previous July to the current June) was reconstructed for a period spanning 1679-2008 AD with an explained variance of 53.1% (1955-2008 AD). Intervals with precipitation more than the 330-year average occurred in 1686-1715, 1727-1741, 1774-1810 and 1871-1923. The intervals 1716-1726, 1740-1773, 1811-1870, 1924-1937 and 1980-2003 had precipitation lower than the 330-year average. Most drought events recorded in historical documents were captured by the reconstruction. Moreover, the reconstruction agreed well with tree-ring-based precipitation at Mt. Helan 400 km northeast of Mt. Xinglong. The results showed that the variability of the East Asian summer monsoon-related precipitation was synchronously at a large spatial and temporal scale within the environmentally sensitive region in northern China. The reconstruction was tested for periodicities by power spectrum analysis. The results showed remarkable 160-, 106.67-, 80-, 22.86-, 6.27- and 2- to 3-year cycles at a 99% confidence level for the past 330 years.</p

Deletion of the mitochondrial calcium uniporter in adipose tissue promotes energy expenditure and alleviates diet-induced obesity

Objective: Studies have shown a correlation between obesity and mitochondrial calcium homeostasis, yet it is unclear whether and how Mcu regulates adipocyte lipid deposition. This study aims to provide new potential target for the treatment of obesity and related metabolic diseases, and to explore the function of Mcu in adipose tissue. Methods: We firstly investigated the role of mitoxantrone, an Mcu inhibitor, in the regulation of glucose and lipid metabolism in mouse adipocytes (3T3-L1 cells). Secondly, C57BL/6J mice were used as a research model to investigate the effects of Mcu inhibitors on fat accumulation and glucose metabolism in mice on a high-fat diet (HFD), and by using CRISPR/Cas9 technology, adipose tissue-specific Mcu knockdown mice (Mcufl/+ AKO) and Mcu knockout of mice (Mcufl/fl AKO) were obtained, to further investigate the direct effects of Mcu on fat deposition, glucose tolerance and insulin sensitivity in mice on a high-fat diet. Results: We found the Mcu inhibitor reduced adipocytes lipid accumulation and adipose tissues mass in mice fed an HFD. Both Mcufl/+ AKO mice and Mcufl/fl AKO mice were resistant to HFD-induced obesity, compared to control mice. Mice with Mcufl/fl AKO showed improved glucose tolerance and insulin sensitivity as well as reduced hepatic lipid accumulation. Mechanistically, inhibition of Mcu promoted mitochondrial biogenesis and adipocyte browning, increase energy expenditure and alleviates diet-induced obesity. Conclusions: Our study demonstrates a link between adipocyte lipid accumulation and mCa2+ levels, suggesting that adipose-specific Mcu deficiency alleviates HFD-induced obesity and ameliorates metabolic disorders such as insulin resistance and hepatic steatosis. These effects may be achieved by increasing mitochondrial biosynthesis, promoting white fat browning and enhancing energy metabolism