Inhibition of NLRP3 inflammasome activation by A20 through modulation of NEK7.

The NLRP3 inflammasome, a pivotal component of innate immunity, has been implicated in various inflammatory disorders. The ubiquitin-editing enzyme A20 is well known to regulate inflammation and maintain homeostasis. However, the precise molecular mechanisms by which A20 modulates the NLRP3 inflammasome remain poorly understood. Here, our study revealed that macrophages deficient in A20 exhibit increased protein abundance and elevated mRNA level of NIMA-related kinase 7 (NEK7). Importantly, A20 directly binds with NEK7, mediating its K48-linked ubiquitination, thereby targeting NEK7 for proteasomal degradation. Our results demonstrate that A20 enhances the ubiquitination of NEK7 at K189 and K293 ubiquitinated sites, with K189 playing a crucial role in the binding of NEK7 to A20, albeit not significantly influencing the interaction between NEK7 and NLRP3. Furthermore, A20 disrupts the association of NEK7 with the NLRP3 complex, potentially through the OTU domain and/or synergistic effect of ZnF4 and ZnF7 motifs. Significantly, NEK7 deletion markedly attenuates the activation of the NLRP3 inflammasome in A20-deficient conditions, both in vitro and in vivo. This study uncovers a mechanism by which A20 inhibits the NLRP3 inflammasome.

One-step preparation of boronic acid-rich hydrothermal spheres for N-glycopeptide analysis from preeclampsia serum.

In this study, we developed a green, one-step hydrothermal carbonization (HTC) method that used water as the sole solvent to create boronic acid group-rich carbonaceous spheres (BCS). When the abundant boronic acid groups on the carbonaceous spheres react with the hydroxyl groups on the glycans in an alkaline environment, the glycopeptides are specifically captured. The results showed that BCS had excellent detection limits (0.1 fmol µL-1), selectivity (1 : 1000), and stability (10 cycles). In addition, the BCS also demonstrated excellent glycopeptide enrichment capabilities in complex biological samples; 219 glycopeptides attributed to 167 glycoproteins and 235 glycopeptides related to 166 glycoproteins in PE patient and normal pregnancy control serum were identified by nano LC-MS/MS, respectively. In addition, the molecular function of heparin binding and biological process of complement activation, positive regulation of immune response, and positive regulation of tumor necrosis factor production were significantly different between PE patients and healthy pregnant women according to gene ontology analysis, indicating that these may be associated with the development of PE.

CircRNA-miRNA networks in regulating bone disease.

Circular RNA (circRNA) is a class of endogenous noncoding RNA (ncRNA), presenting as a special covalent closed loop without a 5' cap or 3' tail, maintaining resistance to RNA exonuclease and keeping high stability. Although lowly expressed in most situations, circRNA makes an active difference in regulating physiological or pathological processes by modulating gene expression by regulation of transcription, protein, and miRNA functions through various mechanisms in particular tissues. Recent studies have demonstrated the roles of the miRNA-circRNA network in the development of several bone diseases such as osteoporosis, a multiple-mechanism disease resulting from defective bone quality and low bone mass, osteoarthritis, whose main pathomechanism is inflammation and articular cartilage degradation, as well as osteosarcoma, known as one of the most common bone cancers. However, the specific mechanism of how circRNA along with miRNA influences those diseases is not well documented, showing potential for the development of new therapies for those bone diseases.

Mechanistic insights into AMPK-SIRT3 positive feedback loop-mediated chondrocyte mitochondrial quality control in osteoarthritis pathogenesis.

Osteoarthritis (OA) is a major cause of disability in the elderly population and represents a significant public health problem and socioeconomic burden worldwide. However, no disease-modifying therapeutics are currently available for OA due to an insufficient understanding of the pathogenesis of this disability. As a unique cell type in cartilage, chondrocytes are essential for cartilage homeostasis and play a critical role in OA pathogenesis. Mitochondria are important metabolic centers in chondrocytes and contribute to cell survival, and mitochondrial quality control (MQC) is an emerging mechanism for maintaining cell homeostasis. An increasing number of recent studies have demonstrated that dysregulation of the key processes of chondrocyte MQC, which involve mitochondrial redox, biogenesis, dynamics, and mitophagy, is associated with OA pathogenesis and can be regulated by the chondroprotective molecules 5' adenosine monophosphate-activated protein kinase (AMPK) and sirtuin 3 (SIRT3). Moreover, AMPK and SIRT3 regulate each other, and their expression and activity are always consistent in chondrocytes, which suggests the existence of an AMPK-SIRT3 positive feedback loop (PFL). Although the precise mechanisms are not fully elucidated and need further validation, the current literature indicates that this AMPK-SIRT3 PFL regulates OA development and progression, at least partially by mediating chondrocyte MQC. Therefore, understanding the mechanisms of AMPK-SIRT3 PFL-mediated chondrocyte MQC in OA pathogenesis might yield new ideas and potential targets for subsequent research on the OA pathomechanism and therapeutics.

γ-Aminobutyric Acid Promotes Osteogenic Differentiation of Mesenchymal Stem Cells by Inducing TNFAIP3.

BACKGROUND: Osteoporosis is the most common metabolic bone disease. There is still an unmet need for novel therapeutic agents that could be beneficial as osteoporosis treatments. It has been reported that the neurotransmitter γ-aminobutyric acid (GABA) might be associated with human bone formation. However, the precise mechanism remains unclear. OBJECTIVE: To investigate the effect of GABA on bone metabolism and explore the possible role of TNFAIP3 in this process. METHODS: GABA had little effect on the proliferation of human mesenchymal stem cells (hMSCs) and RAW 264.7 cells, as indicated by the cell counting kit-8 (CCK-8) assay. The results showed that GABA enhanced the intensity of ALP staining, ALP activity, and accumulation of Ca2+ mineralized nodules in hMSCs during osteogenic induction. RESULTS: The qRT-PCR results indicated that GABA treatment significantly increased the mRNA expression of osteogenic genes in hMSCs. In RAW 264.7 cells, TRAP staining showed that GABA did not alter the number or size of osteoclasts or the expression of osteoclastic genes, which suggests that GABA does not affect osteoclastic differentiation. Mechanistically, GABA treatment significantly induced the sustained expression of TNFAIP3. Furthermore, by knocking down TNFAIP3, the osteogenic effect of GABA was antagonized, which suggests that TNFAIP3 mediates the effects of GABA in hMSCs. CONCLUSION: Our results suggested that GABA treatment positively regulated osteogenic differentiation by upregulating TNFAIP3, while no obvious effect on osteoclastic differentiation was detected. Therefore, our results provide a potential gene therapy for the treatment of osteoporosis and low bone mineral density.

A20: a master regulator of arthritis.

A20, also known as TNF-α-induced protein 3 (TNFAIP3), is an anti-inflammatory protein that plays an important part in both immune responses and cell death. Impaired A20 function is associated with several human inflammatory and autoimmune diseases. Although the role of A20 in mediating inflammation has been frequently discussed, its intrinsic link to arthritis awaits further explanation. Here, we review new findings that further demonstrate the molecular mechanisms through which A20 regulates inflammatory arthritis, and we discuss the regulation of A20 by many factors. We conclude by reviewing the latest A20-associated mouse models that have been applied in related research because they reflect the characteristics of arthritis, the study of which will hopefully cast new light on anti-arthritis treatments.

In situ antitumor vaccination: Targeting the tumor microenvironment.

Tumor microenvironment is known to play important roles in tumor progression. Many therapies, targeting the tumor microenvironment, are designed and applied in the clinic. One of these approaches is in situ antitumor therapy. This way, bacteria, antibodies, plasmid DNA, viruses, and cells are intratumorally delivered into the tumor site as "in-situ antitumor vaccine," which seeks to enhance immunogenicity and generate systemic T cell responses. In addition, this intratumoral therapy can alter the tumor microenvironment from immunosuppressive to immunostimulatory while limiting the risk of systemic exposure and associated toxicity. Contemporarily, promising preclinical results and some initial success in clinical trials have been obtained after intratumoral therapy.

Risk factors analysis for hyperuricemic nephropathy among CKD stages 3-4 patients: an epidemiological study of hyperuricemia in CKD stages 3-4 patients in Ningbo, China.

OBJECTIVE: Uric acid (UA) is a risk marker of CKD and SUA level in CKD 3-4 patients closely correlates with hyperuricemic nephropathy (HN) morbidity. This study was designed to evaluate the risk factors for HN in CKD 3-4 patients. METHODS: The 461 CKD 3-4 patients were recruited and all patients were divided into three groups (24 h UUA normal, underexeret, and overproduct type groups) according to the 24 h UUA level after receiving low purine food for five days. Clinical and biochemical characteristics of CKD patients were collected for the logistic regression analysis. Correlation analysis of the mRNA relative expression level of hUAT and hURAT1 with serum UA (SUA) level also was evaluated. RESULTS: There were significant increases in characteristics including average age, waist-to-height ratio (WHR), SUA levels, HN ratio, TG/HDL ratio, body mass index (BMI), blood pressure (BP), uNgal/Cr. ratio, and uKim-1/Cr. ratio in overproduct type group in comparison with the other two groups. Logistic regression analysis showed SUA, CHO, uKim-1/Cr. ratio and uNgal/Cr. ratio were independent and multiple risk factors for HN. Moreover, hUAT and hURAT1 mRNA relative expression levels were significantly correlated with SUA level in the underexeret type CKD 3-4 patients. CONCLUSIONS: These results showed SUA and other characteristics contributed to HN morbidity in CKD 3-4 patients.