ABCA1 deficiency contributes to podocyte pyroptosis priming via the APE1/IRF1 axis in diabetic kidney disease

Roles of ABCA1 in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is one of the common chronic respiratory diseases, which causes a heavy burden to patients and society. Increasing studies suggest that ABCA1 plays an important role in COPD. ABCA1 belongs to a large class of ATP-binding (ABC) transporters. It is not only involved in the reverse transport of cholesterol, but also in the regulation of apoptosis, pyroptosis, cellular inflammation and cellular immunity. Meanwhile, ABCA1 is involved in several signaling pathways, such as SREBP pathway, LXR pathway, MAPK pathway, p62/mTOR pathway, CTRP1 pathway and so on. In addition, the ABCA1 participates in the disorder of lipid metabolism in COPD by regulating the formation of RCT and HDL, regulates the inflammation of COPD by removing excess cholesterol in macrophages, and promotes the differentiation of COPD phenotype into emphysema type. Accordingly, the ABCA1 may be a therapeutic target for COPD.

LncRNA EMBP1 sponges miR-454-3p to upregulate IRF1 and activate NLRP3-mediated chondrocyte pyroptosis to drive osteoarthritis progression

BACKGROUND

Osteoarthritis (OA) is the most common degenerative joint disease worldwide. Studies have confirmed that pyroptosis is closely associated with the OA onset and progression, particularly via the classical pathway mediated by the NLRP3 inflammasome. However, the intrinsic regulatory mechanisms underlying pyroptosis in OA remain unclear.

METHODS

We conducted RNA sequencing (RNA-seq) analysis on clinical cartilage samples and identified hub genes connecting OA and pyroptosis. We validated NLRP3-mediated pyroptosis activation, evaluated the diagnostic potential of the hub gene, and explored its regulatory role using a papain-induced rabbit OA model and IL-1β-induced chondrocytes. Subsequently, we constructed a competitive endogenous RNA (ceRNA) network based on the hub gene and validated its competitive binding interactions and regulatory function in NLRP3-mediated pyroptosis. Additionally, hub gene interferon regulatory factor 1 (IRF1) serves as a recognized upstream regulator of the novel cell death paradigm PANoptosis, which integrates apoptosis, necrosis, and pyroptosis. We preliminarily explored the potential molecular mechanisms of PANoptosis in OA through clinical sample analysis and in vitro experiments.

RESULTS

RNA-seq revealed that IRF1, a hub gene linking OA and pyroptosis, is upregulated in OA cartilage and is associated with NLRP3, consistent with the in vivo and in vitro results. Dual-luciferase assays, clinical sample analysis, and in vitro experiments confirmed the competitive binding of the embigin pseudogene 1 (EMBP1)/miR-454-3p/IRF1 ceRNA network. Silencing EMBP1 increased miR-454-3p, inhibiting IRF1 and NLRP3-mediated pyroptosis in vitro; however, miR-454-3p inhibitor rescue experiments abolished the beneficial effects of si-EMBP1. Furthermore, we preliminarily characterized the occurrence of PANoptosis in OA and provided initial evidence suggesting a potential regulatory role for the EMBP1/miR-454-3p/IRF1 axis in this process.

CONCLUSIONS

In OA, EMBP1 acts as a sponge for miR-454-3p, inhibiting its negative regulatory effect on IRF1 and exacerbating NLRP3-mediated chondrocyte pyroptosis. Furthermore, EMBP1/miR-454-3p/IRF1-mediated pyroptosis may be integrated into the broader PANoptosis process, interacting with apoptosis and necrosis to influence OA progression.

Mechanistic Insights Into Redox Damage of the Podocyte in Hypertension

Podocytes are specialized cells within the glomerular filtration barrier, which are crucial for maintaining glomerular structural integrity and convective ultrafiltration. Podocytes exhibit a unique arborized morphology with foot processes interfacing by slit diaphragms, ladder-like, multimolecular sieves, which provide size and charge selectivity for ultrafiltration and transmembrane signaling. Podocyte dysfunction, resulting from oxidative stress, dysregulated prosurvival signaling, or structural damage, can drive the development of proteinuria and glomerulosclerosis in hypertensive nephropathy. Functionally, podocyte injury leads to actin cytoskeleton rearrangements, foot process effacement, dysregulated slit diaphragm protein expression, and impaired ultrafiltration. Notably, the renin-angiotensin system plays a pivotal role in podocyte function, with beneficial AT2R (angiotensin receptor 2)-mediated nitric oxide (NO) signaling to counteract AT1R (angiotensin receptor 1)-driven calcium (Ca2+) influx and oxidative stress. Disruption of this balance contributes significantly to podocyte dysfunction and drives albuminuria, a marker of kidney damage and overall disease progression. Oxidative stress can also lead to sustained ion channel-mediated Ca2+ influx and precipitate cytoskeletal disorganization. The complex interplay between GPCR (G-protein coupled receptor) signaling, ion channel activation, and redox injury pathways underscores the need for additional research aimed at identifying targeted therapies to protect podocytes and preserve glomerular function. Earlier detection of albuminuria and podocyte injury through routine noninvasive diagnostics will also be critical in populations at the highest risk for the development of hypertensive kidney disease. In this review, we highlight the established mechanisms of oxidative stress-mediated podocyte damage in proteinuric kidney diseases, with an emphasis on a hypertensive renal injury. We will also consider emerging therapies that have the potential to selectively protect podocytes from redox-related injury.

Significance of pyroptosis-related genes in the diagnosis and classification of diabetic kidney disease

OBJECTIVE

This study aimed to identify the potential biomarkers associated with pyroptosis in diabetic kidney disease (DKD).

METHODS

Three datasets from the Gene Expression Omnibus (GEO) were downloaded and merged into an integrated dataset. Differentially expressed genes (DEGs) were filtered and intersected with pyroptosis-related genes (PRGs). Pyroptosis-related DEGs (PRDEGs) were obtained and analyzed using functional enrichment analysis. Random forest, Least Absolute Shrinkage and Selection Operator, and logistic regression analyses were used to select the features of PRDEGs. These feature genes were used to build a diagnostic prediction model, identify the subtypes of the disease, and analyze their interactions with transcription factors (TFs)/miRNAs/drugs and small molecules. We conducted a comparative analysis of immune cell infiltration at different risk levels of pyroptosis. qRT-PCR was used to validate the expression of the feature genes.

RESULTS

A total of 25 PRDEGs were obtained. These genes were coenriched in biological processes and pathways, such as the regulation of inflammatory responses. Five key genes (CASP1, CITED2, HTRA1, PTGS2, S100A12) were identified and verified using qRT-PCR. The diagnostic model based on key genes has a good diagnostic prediction ability. Five key genes interacted with TFs and miRNAs in 67 and 80 pairs, respectively, and interacted with 113 types of drugs or molecules. Immune infiltration of samples with different pyroptosis risk levels showed significant differences. Thus, CASP1, CITED2, HTRA1, PTGS2 and S100A12 are potential DKD biomarkers.

CONCLUSION

Genes that regulate pyroptosis can be used as predictors of DKD. Early diagnosis of DKD can aid in its effective treatment.

Podocyte programmed cell death in diabetic kidney disease: Molecular mechanisms and therapeutic prospects

Diabetic kidney disease (DKD) is the primary cause of chronic kidney and end-stage renal disease. Glomerular podocyte loss and death are pathological hallmarks of DKD, and programmed cell death (PCD) in podocytes is crucial in DKD progression. PCD involves apoptosis, autophagy, ferroptosis, pyroptosis, and necroptosis. During DKD, PCD in podocytes is severely impacted and primarily characterized by accelerated podocyte apoptosis and suppressed autophagy. These changes lead to a gradual decrease in podocyte numbers, impairing the glomerular filtration barrier function and accelerating DKD progression. However, research on the interactions between the different types of PCD in podocytes is lacking. This review focuses on the novel roles and mechanisms of PCD in the podocytes of patients with DKD. Additionally, we summarize clinical drugs capable of regulating podocyte PCD, present challenges and prospects faced in developing drugs related to podocyte PCD and suggest that future research should further explore the detailed mechanisms of podocyte PCD and interactions among different types of PCD.

The 14th International Podocyte Conference 2023: from podocyte biology to glomerular medicine

The 14th International Podocyte Conference took place in Philadelphia, Pennsylvania, USA from May 23 to 26, 2023. It commenced with an early-career researchers' meeting on May 23, providing young scientists with a platform to present and discuss their research findings. Throughout the main conference, 29 speakers across 9 sessions shared their insights on podocyte biology, glomerular medicine, novel technologic advancements, and translational approaches. Additionally, the event featured 3 keynote lectures addressing engineered chimeric antigen receptor T cell- and mRNA-based therapies and the use of biobanks for enhanced disease comprehension. Furthermore, 4 brief oral abstract sessions allowed scientists to present their findings to a broad audience. The program also included a panel discussion addressing the challenges of conducting human research within the American Black community. Remarkably, after a 5-year hiatus from in-person conferences, the 14th International Podocyte Conference successfully convened scientists from around the globe, fostering the presentation and discussion of crucial research findings, as summarized in this review. Furthermore, to ensure continuous and sustainable education, research, translation, and trial medicine related to podocyte and glomerular diseases for the benefit of patients, the International Society of Glomerular Disease was officially launched during the conference.

Activation of APE1 modulates Nrf2 protected against acute liver injury by inhibit hepatocyte ferroptosis and promote hepatocyte autophagy

BACKGROUND

Apurinic/apyrimidinic endonuclease 1/redox effector factor 1 (APE1/Ref-1) plays a crucial role in DNA base excision repair, cell apoptosis, cell signaling, and the regulation of transcription factors through redox modulation and the control of reactive oxygen species (ROS). However, the connection between APE1 and acute liver injury (ALI) remains enigmatic. This study aims to unravel the molecular mechanisms underlying ALI and shed light on the role of APE1 in this context.

METHOD

We induced acute liver injury (ALI) in mice by lipopolysaccharide/D-galactosamine (LPS/GalN) and intervened with the APE1 inhibitor E3330. We examined the expression of APE1 in ALI mice and ALI patient tissues after E3330 intervention, Additionally, we measured hepatic oxidative stress, ferroptosis, and autophagy marker proteins and genes. In establishing an AML-12 liver cell injury model, we utilized the Nrf2 activator tert-butylhydroquinone (TBHQ) as an intervention and examined APE1, Nrf2, ferroptosis-related proteins, and autophagy marker proteins and mRNA.

RESULTS

Both ALI patients and ALI mice exhibited reduced APE1 expression levels. After E3330 intervention, there was a significant exacerbation of liver injury, oxidative stress, and a reduction in the expression of proteins, including GPX4, X-CT, ATG3, ATG5, and LC3 (LC3I/II). Consistent results were also observed in AML-12 cells. With TBHQ intervention, Nrf2 expression increased, along with the expression of proteins associated with iron death and autophagy. Mechanistically, APE1 activation regulates Nrf2 to inhibit ferroptosis and promote autophagy in hepatocytes.

CONCLUSION

The data suggest that APE1 is a pivotal player in ALI, closely linked to its regulation of Nrf2. Strategies involving APE1 activation to modulate Nrf2, thereby inhibiting hepatocyte ferroptosis and promoting autophagy, may represent innovative therapeutic approaches for ALI. Additionally, tert-butylhydroquinone (TBHQ) holds significant promise in the treatment of acute liver injury.