UNC93B1 Mediates the Effects of cGAS-STING on ER Stress and Iron Death, and Reduces Renal Toxicity in Cadmium-Exposed Rats.

BACKGROUND: Long-term exposure to cadmium can induce renal toxicity in rats, leading to endoplasmic reticulum (ER) stress and iron death. Notably, in cadmium-exposed rats, there is an increased expression of UNC93B1 (unc-93 homolog B1). Consequently, our investigation aims to determine the impact of UNC93B1 on ER stress and iron death in cadmium-exposed rats by modulating the cGAS-STING (cyclic GMP-AMP synthase-stimulator of interferon genes) pathway. METHODS: A cadmium-exposed rat model was established by intrabacally injecting chromium chloride (5 mg/kg, once a day for 4 weeks), and the levels of UCd (urine cadmium), UNAG (urine N-acetyl-ß-D-glucosaminidase), and UCr (urine creatinine) in urine were assessed. A silent UNC93B1 lentivirus was constructed, and STING agonists were procured and administered to the rats. Subsequently, kidney tissues were extracted post-mortem, and pathological changes in renal tissue were observed through hematoxylin and eosin (HE) staining. The expression and mRNA levels of UNC93B1, cGAS, and STING were examined using western blot (WB) and polymerase chain reaction (PCR). Autophagy proteins (light chain 3 (LC3), Beclin-1, p62) were also assessed by WB. Additionally, iron concentration was determined using a kit, while oxidative stress markers (cytochrome oxidase subunit 2 (COX2), glutathione peroxidase 4 (GPX4), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH)) were measured through enzyme-linked immunosorbent assay (ELISA). Furthermore, endoplasmic reticulum stress proteins (protein kinase RNA-like ER kinase (PERK), CCAAT enhance-binding protein homologous protein (CHOP), activating transcription factor-4 (ATF4)) were analyzed by WB. RESULTS: Wstaining, WB, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), ELISA, and HE staining collectively revealed a heightened expression of UNC93B1, cGAS, and STING, accompanied by increased levels of autophagy, oxidative stress, and ER stress in cadmium-exposed rats (p < 0.05). Nephrotoxicity exhibited a reduction following the inhibition of UNC93B1, leading to decreased levels of oxidative stress, autophagy, and ER stress (p < 0.05). Notably, this observed phenomenon was reversed upon the addition of STING agonists, suggesting that UNC93B1 might exert a nephroprotective effect in cadmium-exposed rats through modulation of the cGAS-STING pathway. CONCLUSIONS: The inhibition of UNC93B1 mitigates nephrotoxicity in cadmium-exposed rats, and this protective effect is mechanistically linked to the cGAS-STING pathway.

GDF11 inhibits the malignant progression of hepatocellular carcinoma via regulation of the mTORC1­autophagy axis.

Hepatocellular carcinoma (HCC) is a common malignant tumor, which is associated with a poor prognosis and high mortality rate. It is well known that growth differentiation factor 11 (GDF11) acts as a tumor suppressor in various types of cancer, including HCC. The present study aimed to determine the tumor-suppressive properties of GDF11 in HCC and to assess the intrinsic mechanisms. In the present study, the human hepatoma cell line Huh-7 was transfected with the GDF11 overexpression plasmid (Oe-GDF11) for gain-of-function experiments to investigate the effects of GDF11 on the biological behaviors of HCC cells, including proliferation, colony formation, apoptosis, cell cycle arrest, migration, invasion, epithelial-mesenchymal transition (EMT) and angiogenesis. The proliferation, colony formation, apoptosis, cell cycle, migration, invasion and angiogenesis of HCC cells were assessed by CCK-8, EdU staining, colony formation, flow cytometry, wound healing, Transwell and tube formation assays, respectively. Apoptosis-, cell cycle-, EMT-related key factors were also determined by western blot assay. Furthermore, Oe-GDF11-transfected Huh-7 cells were treated with the mammalian target of rapamycin (mTOR) activator MHY1485 for rescue experiments to explore whether GDF11 could exert antitumor effects against HCC via mediating the mTOR complex 1 (mTORC1)-autophagy axis. In the present study, GDF11 was verified to be lowly expressed in HCC cells. Overexpression of GDF11 inhibited the proliferation, colony formation, migration, invasion, EMT and angiogenesis of HCC cells, and facilitated the apoptosis and cell cycle arrest of HCC cells. Additionally, it was verified that overexpression of GDF11 inactivated the mTORC1 signaling pathway to enhance autophagy in HCC cells. Treatment with the mTOR activator MHY1485 partially reversed the tumor-suppressive effects of GDF11 overexpression on HCC. In conclusion, GDF11 may exert tumor-suppressive properties in HCC cells through inactivating the mTORC1 signaling pathway to strengthen autophagy.

Evaluation of the relationship between cardiac calcification and cardiovascular disease using the echocardiographic calcium score in patients undergoing peritoneal dialysis: a cross-sectional study

INTRODUCTION@#An echocardiographic calcium score (ECS) predicts cardiovascular disease (CVD) in the general population. Its utility in peritoneal dialysis (PD) patients is unknown.@*METHODS@#This cross-sectional study assessed 125 patients on PD. The ECS (range 0-8) was compared between subjects with CVD and those without.@*RESULTS@#Among the subjects, 54 had CVD and 71 did not. Subjects with CVD were older (69 years vs. 56 years, P < 0.001) and had a higher prevalence of diabetes mellitus (DM) (81.5% vs. 45.1%, P < 0.001). They had lower diastolic blood pressure (72 mmHg vs. 81 mmHg, P < 0.001), lower phosphate (1.6 mmol/L vs. 1.9 mmol/L, P = 0.002), albumin (30 g/L vs. 32 g/L, P = 0.001), parathyroid hormone (34.4 pmol/L vs. 55.8 pmol/L, P = 0.002), total cholesterol (4.5 vs. 4.9, P = 0.047), LDL cholesterol (2.4 mmol/L vs. 2.8 mmol/L, P = 0.019) and HDL cholesterol (0.8 mmol/L vs. 1.1 mmol/L, P = 0.002). The ECS was found to be higher in subjects with CVD than in those without (2 vs. 1, P = 0.001). On multivariate analysis, only DM and age were independently associated with CVD.@*CONCLUSION@#The ECS was significantly higher in PD patients with CVD than in those without, reflecting a higher vascular calcification burden in the former. It is a potentially useful tool to quantify vascular calcification in PD patients.

Type VI secretion system-associated FHA domain protein TagH regulates the hemolytic activity and virulence of Vibrio cholerae.

The type VI secretion system (T6SS) and hemolysin HlyA are important virulence factors in Vibrio cholerae. The forkhead-associated (FHA) domain is a conserved phosphopeptide binding domain that exists in many regulatory modules. The FHA domain protein-encoding gene is conserved in the T6SS gene cluster and regulates the assembly and secretion of the T6SS. This study shows for the first time that the FHA domain protein TagH plays a role in controlling the hemolytic activity of V. cholerae, in addition to regulating the T6SS. TagH negatively regulates HlyA expression at the transcriptional and post-translational levels. The phosphopeptide binding sites of the FHA domain of TagH play a key role in the regulation of hemolytic activity. The deletion of tagH enhances the intestinal pathogenicity and extraintestinal invasion ability of V. cholerae, which mainly depend on the expression of HlyA. This study provides evidence that helps unravel the novel regulatory role of TagH in HlyA and provides critical insights which will aid in the development of strategies to manage HlyA.

Identification of Siglec Ligands Using a Proximity Labeling Method.

Siglecs are a family of receptor-type glycan recognition proteins (lectins) involved in self-nonself discrimination by the immune system. Identification of Siglec ligands is necessary to understand how Siglec-ligand interaction translates into biological outcomes. However, this is challenging because the interaction is weak. To facilitate identification of Siglec ligands, we adopted a proximity labeling method based on the tyramide radicalization principle. Cells that express Siglec ligands were labeled with Siglec-peroxidase complexes and incubated with biotin tyramide and hydrogen peroxide to generate short-lived tyramide radicals that covalently label the proteins near the Siglec-peroxidase complex. A proof-of-principle experiment using CD22 (Siglec-2) probe identified its known ligands on B cells, including CD22 itself, CD45, and IgM, among others, demonstrating the validity of this method. The specificity of labeling was confirmed by sialidase treatment of target cells and using glycan recognition-deficient mutant CD22 probes. Moreover, possible interactions between biotin-labeled proteins were revealed by literature-based protein-protein interaction network analysis, implying the presence of a molecular cluster comprising CD22 ligands. Further application of this method identified CD44 as a hitherto unknown Siglec-15 ligand on RAW264.7-derived osteoclasts. These results demonstrated the utility of proximity labeling for the identification of Siglec ligands, which may extend to other lectins.