Diabetic nephropathy (DN) has been associated with the presence of lipid deposition. We hypothesized that the disruption of intracellular cholesterol feedback may contribute to DN. Diabetes was induced by high fat/sucrose diet and low-dose intraperitoneal injection of streptozocin (STZ) in male Sprague-Dawley rats. Then diabetic rats were randomly divided into two groups: untreated diabetic group (DM) and atorvastatin-treated group (DM + AT). We found that the levels of serum blood urea nitrogen and creatinine, as well as 24-hour urine protein and urinary neutrophil gelatinase-associated lipocalin, were significantly increased in diabetic rats. This result indicated that the diabetic rats suffered from functional renal damage. We also observed lipid droplet accumulation and increase in 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoAR), low density lipoprotein receptor (LDLr), sterol regulatory element binding protein-2 (SREBP-2), and SREBP-cleavage activating protein (SCAP) in the kidneys of diabetic rats. However, atorvastatin ameliorated renal lipid accumulation and improved the renal function of diabetic rats despite an increase in mRNA and protein expressions of HMG-CoAR, LDLr, and SREBP-2. These results demonstrated that intracellular cholesterol feedback regulation is disrupted in rats with type 2 diabetes, thereby causing renal cholesterol accumulation. Atorvastatin ameliorated renal cholesterol accumulation by reducing renal cholesterol synthesis.

Background: Glucose cotransporter (SGLT) 2 suppression provides potent renal protective effect during diabetic kidney disease (DKD). This work aimed to explore how empagliflozin (EMPA, the selective and strong inhibitor of SGLT2) affected renal lipid deposition among patients undergoing type 2 diabetes mellitus (T2DM), a T2DM mouse model and human renal proximal tubular epithelial (HK-2) cells. Methods: This work divided subjects as 3 groups: non-diabetic volunteers, patients treated with metformin and those treated with metformin plus EMPA. In an in vivo study, EMPA was adopted for treating db/db mice that were raised with the basal diet or the high-advanced glycation end products (AGEs) diet. In addition, AGEs and/or EMPA was utilized to treat HK-2 cells in vitro. Results: Results showed that diabetic patients treated with metformin plus EMPA had lower AGEs levels and renal fat fraction (RFF) than those treated with metformin. Moreover, a significant and positive association was found between AGEs and RFF. Results from the basic study showed that EMPA decreased cholesterol level, tubular lipid droplets, and protein levels related to cholesterol metabolism in AGEs-mediated HK-2 cells, kidneys of db/db mice and those fed with the high-AGEs diet. Additionally, EMPA decreased AGEs levels in serum while inhibiting the expression of receptor of AGEs (RAGE) in vitro and in vivo. Conclusion: EMPA inhibited the AGEs-RAGE pathway, thereby alleviating diabetic renal tubular cholesterol accumulation.

Monoclonal antibodies against calcitonin gene-related peptide (CGRP) or its receptor are efficacious for the prevention of migraine headaches. The downstream molecular mechanisms following ligand-receptor blockade by which these antibodies prevent CGRP signaling through CGRP receptors have not been demonstrated. Here we produced tool monoclonal functional antagonist antibodies against CGRP and its canonical receptor and developed a novel cellular model using fluorogen-activated protein technology that allows detection of CGRP receptor internalization by flow cytometry and, for an extended time course, visualization by confocal microscopy. Using this cell model we showed that these antagonist antibodies block both CGRP-induced cAMP signaling and CGRP receptor internalization. At least 10-fold higher concentrations of either antibody are necessary to block CGRP receptor internalization compared with cAMP accumulation in our cell model. These data reinforce our understanding of how monoclonal functional antagonist antibodies interfere with CGRP signaling.

Subterranean rodents have evolved many features to adapt to their hypoxic environment. The brain is an organ that is particularly vulnerable to damage caused by exposure to hypoxic conditions. To investigate the mechanisms of adaption to a hypoxic underground environment, we carried out a cross-species brain transcriptome analysis by RNA sequencing and identified genes that are differentially expressed between the subterranean vole Lasiopodomys mandarinus and the closely related above-ground species Lasiopodomys brandtii under chronic hypoxia [10.0% oxygen (O₂)] and normoxia (20.9% O₂). A total of 355 million clean reads were obtained, including 69,611 unigenes in L. mandarinus and 69,360 in L. brandtii. A total of 235 and 92 differentially expressed genes (DEGs) were identified by comparing the hypoxic and control groups of L. mandarinus and L. brandtii, respectively. A Gene Ontology (GO) analysis showed that upregulated DEGs in both species had similar functions in response to hypoxia, whereas downregulated DEGs in L. mandarinus were enriched GO terms related to enzymes involved in aerobic reactions. In the Kyoto Encyclopedia of Genes and Genomes pathway analysis, upregulated DEGs in L. mandarinus were associated with angiogenesis and the increased O₂ transport capacity of red blood cells, whereas downregulated DEGs were associated with immune responses. On the other hand, upregulated DEGs in L. brandtii were associated with cell survival, vascular endothelial cell proliferation, and neuroprotection, while downregulated genes were related to the synaptic transmission by neurons. L. mandarinus actively adapts its physiological functions to hypoxic conditions, for instance by increasing O₂ transport capacity and modulating O₂ consumption. In contrast, L. brandtii reacts passively to hypoxia by decreasing overall activity in order to reduce O₂ consumption. These results provide insight into hypoxia adaptation mechanisms in subterranean rodents that may be applicable to humans living at high altitudes or operating in other O₂-poor environments.

Background and Aims: Thioredoxin-interacting protein (TXNIP), a crucial modulator of the redox system, plays a crucial role in modulating lipid/glucose metabolism. Hence, this study aimed to explore whether circulating TXNIP is associated with non-alcoholic fatty liver disease (NAFLD) among patients with type 2 diabetes mellitus (T2DM). Methods: We enrolled 110 new patients with T2DM. In this study, we determined hepatic fat fraction (HFF), which represents a hepatic fat level, by Dixon magnetic resonance imaging. TXNIP and the other biochemical profiles of the patients were measured using fasting plasma. Results: Among the 110 patients with T2DM, 41 were classified as without fatty liver, whereas 34 and 35 were with mild and moderate-to-severe fatty liver, respectively. The patients with diabetes and advanced fatty liver had significantly higher TXNIP levels (P < 0.001) than other patients. The prevalence of severe NAFLD showed an increasing trend with the increase in TXNIP quartiles (for all trends, P < 0.05). HFF showed a positive correlation with TXNIP (r = 0.516, P < 0.001). Even main risk factors were adjusted, TXNIP level was associated with NAFLD as analyzed by logistic regression. Conclusion: TXNIP level remarkably increases among diabetics, which shows its positive relationship with the severity of NAFLD. TXNIP is a promising NAFLD biomarker that offers an efficient way to evaluate and monitor fatty liver progression among patients with T2DM.