Polysulfide-mediated sulfhydration of SIRT1 prevents diabetic nephropathy by suppressing phosphorylation and acetylation of p65 NF-κB and STAT3

Atractylenolide-I Alleviates Hyperglycemia-Induced Heart Developmental Malformations through Direct and Indirect Modulation of the STAT3 Pathway

BACKGROUND

Gestational diabetes could elevate the risk of congenital heart defects (CHD) in infants, and effective preventive and therapeutic medications are currently lacking. Atractylenolide-I (AT-I) is the active ingredient of Atractylodes Macrocephala Koidz (known as Baizhu in China), which is a traditional pregnancy-supporting Chinese herb.

PURPOSE

In this study, we investigated the protective effect of AT-I on the development of CHD in embryos exposed to high glucose (HG).

STUDY DESIGN AND METHODS

First, systematic review search results revealed associations between gestational diabetes mellitus (GDM) and cardiovascular malformations. Subsequently, a second systematic review indicated that heart malformations were consistently associated with oxidative stress and cell apoptosis. We assessed the cytotoxic impacts of Atractylenolide compounds (AT-I, AT-II, and AT-III) on H9c2 cells and chick embryos, determining an optimal concentration of AT-I for further investigation. Second, immunofluorescence, western blot, Polymerase Chain Reaction (PCR), and flow cytometry were utilized to delve into the mechanisms through which AT-I mitigates oxidative stress and apoptosis in cardiac cells. Molecular docking was employed to investigate whether AT-I exerts cardioprotective effects via the STAT3 pathway. Then, we developed a streptozotocin-induced diabetes mellitus (PGDM) mouse model to evaluate AT-I's protective efficacy in mammals. Finally, we explored how AT-I protects hyperglycemia-induced abnormal fetal heart development through microbiota analysis and untargeted metabolomics analysis.

RESULTS

The study showed the protective effect of AT-I on embryonic development using a chick embryo model which rescued the increase in the reactive oxygen species (ROS) and decrease in cell survival induced by HG. We also provided evidence suggesting that AT-I might directly interact with STAT3, inhibiting its phosphorylation. Further, in the PGDM mouse model, we observed that AT-I not only partially alleviated PGDM-related blood glucose issues and complications but also mitigated hyperglycemia-induced abnormal fetal heart development in pregnant mice. This effect is hypothesized to be mediated through alterations in gut microbiota composition. We proposed that dysregulation in microbiota metabolism could influence the downstream STAT3 signaling pathway via EGFR, consequently impacting cardiac development and formation.

CONCLUSIONS

This study marks the first documented instance of AT-I's effectiveness in reducing the risk of early cardiac developmental anomalies in fetuses affected by gestational diabetes. AT-I achieves this by inhibiting the STAT3 pathway activated by ROS during gestational diabetes, significantly reducing the risk of fetal cardiac abnormalities. Notably, AT-I also indirectly safeguards normal fetal cardiac development by influencing the maternal gut microbiota and suppressing the EGFR/STAT3 pathway.

Sodium thiosulfate: A donor or carrier signaling molecule for hydrogen sulfide?

Sodium thiosulfate has been used for decades in the treatment of calciphylaxis and cyanide detoxification, and has recently shown initial therapeutic promise in critical diseases such as neuronal ischemia, diabetes mellitus, heart failure and acute lung injury. However, the precise mechanism of sodium thiosulfate remains incompletely defined and sometimes contradictory. Although sodium thiosulfate has been widely accepted as a donor of hydrogen sulfide (H2S), emerging findings suggest that it is the executive signaling molecule for H2S and that its effects may not be dependent on H2S. This article presents an overview of the current understanding of sodium thiosulfate, including its synthesis, biological characteristics, and clinical applications of sodium thiosulfate, as well as the underlying mechanisms in vivo. We also discussed the interplay of sodium thiosulfate and H2S. Our review highlights sodium thiosulfate as a key player in sulfide signaling with the broad clinical potential for the future.

SIRT1 alleviates Cd nephrotoxicity through NF-κB/p65 deacetylation-mediated pyroptosis in rat renal tubular epithelial cells

Cadmium (Cd) is a widely distributed environmental pollutant, primarily causing nephrotoxicity through renal proximal tubular cell impairment. Pyroptosis is an inflammation-related nucleotide-binding oligomerization segment-like receptor family 3 (NLRP3)-dependent pathway for programmed cell death. We previously reported that inappropriate inflammation caused by Cd is a major contributor to kidney injury. Therefore, research on Cd-induced inflammatory response and pyroptosis may clarify the mechanisms underlying Cd-induced nephrotoxicity. In this study, we observed that Cd-induced nephrotoxicity is associated with NLRP3 inflammasome activation, leading to an increase in proinflammatory cytokine expression and secretion, as well as pyroptosis-related gene upregulation, both in primary rat proximal tubular (rPT) cells and kidney tissue from Cd-treated rats. In vitro, these effects were significantly abrogated through siRNA-based Nlrp3 silencing; thus, Cd may trigger pyroptosis through an NLRP3 inflammasome-dependent pathway. Moreover, Cd exposure considerably elevated reactive oxygen species (ROS) content. N-acetyl-l-cysteine, an ROS scavenger, mitigated Cd-induced NLRP3 inflammasome activation and subsequent pyroptosis. Mechanistically, Cd hindered the expression and deacetylase activity of SIRT1, eventually leading to a decline in SIRT1-p65 interactions, followed by an elevation in acetylated p65 levels. The administration of resveratrol (a SIRT1 agonist) or overexpression of Sirt1 counteracted Cd-induced RELA/p65/NLRP3 pathway activation considerably, leading to pyroptosis. This is the first study to reveal significant contributions of SIRT1-triggered p65 deacetylation to pyroptosis and its protective effects against Cd-induced chronic kidney injury. Our results may aid in developing potential therapeutic strategies for preventing Cd-induced pyroptosis through SIRT1-mediated p65 deacetylation.

Human Menstrual Blood-Derived Stem Cells Protect against Tacrolimus-Induced Islet Dysfunction via Cystathionine β-Synthase Mediated IL-6/STAT3 Inactivation

Diabetes imposes a huge burden worldwide. Islet transplantation is an alternative therapy for diabetes. However, tacrolimus, a kind of immunosuppressant after organ transplantation, is closely related to post-transplant diabetes mellitus. Mesenchymal stem cells (MSCs) have attracted interest for their potential to alleviate diabetes. In vivo experiments revealed that human menstrual blood-derived stem cells (MenSCs) treatment improved tacrolimus-induced blood glucose, body weight, and glucose tolerance disorders in mice. RNA sequencing was used to analyze the potential therapeutic targets of MenSCs. In this study, we illustrated that cystathionine β-synthase (CBS) contributed to tacrolimus -induced islet dysfunction. Using β-cell lines (MIN6, β-TC-6), we demonstrated that MenSCs ameliorated tacrolimus-induced islet dysfunction in vitro. Moreover, MenSC reduced the tacrolimus-induced elevation of CBS levels and significantly enhanced the viability, anti-apoptotic ability, glucose-stimulated insulin secretion (GSIS), and glycolytic flux of β-cells. We further revealed that MenSCs exerted their therapeutic effects by inhibiting CBS expression to activate the IL6/JAK2/STAT3 pathway. In conclusion, we showed that MenSCs may be a potential strategy to improve tacrolimus-induced islet dysfunction.

Exogenous hydrogen sulfide prevents SOD2 degradation to safeguard renal function in diabetic kidney disease

Diabetic kidney disease (DKD) is a major contributor to chronic kidney disease. Hydrogen sulfide (H2S) serves as an endogenous gaseous signaling molecule capable of safeguarding renal function within the context of DKD. However, the underlying mechanisms need to be elucidated. This study was undertaken to unveil the mechanisms by which H2S counteracts against DKD. Utilizing mice and human renal tubular epithelial (HK-2) cells, we demonstrated a reduction in cystathionine-γ-lyase/H2S levels within renal tissues of db/db mice and in HK-2 cells subjected to hyperglycemic and hyperlipidemic environments. Notably, we observed that sodium hydrosulfide (NaHS) supplementation could serve as an exogenous source of H2S. Exogenous H2S exhibited the capacity to mitigate the accumulation of reactive oxygen species and attenuate the degradation of superoxide dismutase 2 (SOD2) by Lon protease homolog 1 induced by hyperglycemia and hyperlipidemia, thus affording cellular protection against mitochondrial apoptosis. Consequently, NaHS treatment led to decreased serum levels of blood urea nitrogen and serum creatinine, reflecting alleviated renal damage and thereby preserving renal function in db/db mice. Based on these findings, we propose that exogenous H2S exerts a protective role against DKD by inhibiting SOD2 degradation.

Cell division cycle 42 attenuates high glucose-treated renal tubular epithelial cell apoptosis, fibrosis, and inflammation, but activates the PAK1/AKT pathway

BACKGROUND

Cell division cycle 42 (CDC42) modulates metabolism, inflammation, and fibrosis to engage in the pathology of diabetic complications. This study intended to further investigate the influence of CDC42 on viability, apoptosis, inflammation, epithelial-mesenchymal transition, and fibrosis in high glucose (HG)-treated renal tubular epithelial cells.

METHODS

HK-2 cells were exposed to HG medium (30 mM) to establish the diabetic nephropathy (DN) cellular model, then the cells were transfected with scramble overexpression control (oeNC) or CDC42 overexpression (oeCDC42) vectors.

RESULTS

Both the level of CDC42 mRNA and protein were decreased in HG-treated HK-2 cells in a dose- and time-dependent manner. Then HG-treated HK-2 cells were proposed for the following experiments. It was found that CDC42 increased CCK-8 detected viability and EdU positive cells. On the contrary, CDC42 reduced cell apoptosis, which was reflected by decreased TUNEL positive rate, increased BCL2, and reduced BAX. Interestingly, CDC42 inhibited fibrosis, which was reflected by increased E-Cadherin, as well as decreased Vimentin, TGF-β1, Collagen1, and α-SMA. Apart from these, CDC42 also attenuated proinflammatory cytokine production, including TNF-α, IL-1β, and IL-6. Moreover, CDC42 activated the PAK1/AKT pathway, which was reflected by increased p-PAK1 and p-AKT. However, CDC42 did not affect p-ERK.

CONCLUSION

CDC42 may retard DN progression via its regulation of renal tubular epithelial cell functions, which may be due to its stimulation of the PAK1/AKT pathway.

NF-ĸB axis in diabetic neuropathy, cardiomyopathy and nephropathy: A roadmap from molecular intervention to therapeutic strategies

Diabetes mellitus (DM) is a metabolic illness defined by elevated blood glucose levels, mediating various tissue alterations, including the dysfunction of vital organs. Diabetes mellitus (DM) can lead to many consequences that specifically affect the brain, heart, and kidneys. These issues are known as neuropathy, cardiomyopathy, and nephropathy, respectively. Inflammation is acknowledged as a pivotal biological mechanism that contributes to the development of various diabetes consequences. NF-κB modulates inflammation and the immune system at the cellular level. Its abnormal regulation has been identified in several clinical situations, including cancer, inflammatory bowel illnesses, cardiovascular diseases, and Diabetes Mellitus (DM). The purpose of this review is to evaluate the potential impact of NF-κB on complications associated with DM. Enhanced NF-κB activity promotes inflammation, resulting in cellular harm and compromised organ performance. Phytochemicals, which are therapeutic molecules, can potentially decline the NF-κB level, therefore alleviating inflammation and the progression of problems correlated with DM. More importantly, the regulation of NF-κB can be influenced by various factors, such as TLR4 in DM. Highlighting these factors can facilitate the development of novel therapies in the future.

Endotoxin tolerance ameliorates lipopolysaccharide/D-galactosamine-induced acute liver failure by negative regulation of the NF-κB/NLRP3 and activation of Nrf2/HO-1 via Sitr1

Acute liver failure (ALF) is a potentially fatal disorder characterized by extensive hepatocyte necrosis and rapid decline in liver function. Numerous factors, including oxidative stress, cell death, and inflammatory responses, are associated with its pathogenesis. Endotoxin tolerance (ET) refers to the phenomenon in which the body or cells exhibit low or no response to high-dose lipopolysaccharide (LPS) stimulation after pre-stimulation with low-dose LPS. However, the specific mechanism through which ET regulates LPS/D-galactosamine (D-GalN)-induced ALF remains unclear. An ALF mouse model was established by intraperitoneal injection of D-GalN (400 mg/kg) and LPS (10 mg/kg). A low dose of LPS (0.1 mg/kg/d) was continuously administered to mice for 5 d before modeling to assess the protective effect of ET. The data from this study showed that ET alleviated the inflammatory response in mice with LPS/D-GalN-induced ALF. ET inhibited LPS-induced oxidative damage and pyroptosis in macrophages in vitro. RNA sequencing analysis showed that the NF-κB/NLRP3 pathway was linked to the anti-inflammatory and antioxidative effects of ET. Furthermore, using western blot, RT-qPCR, and immunofluorescence, we verified that ET inhibited the NF-κB/NLRP3 pathway and triggered the Nrf2/HO-1 signaling pathway to attenuate oxidative stress and cell pyroptosis. Sirt1 knockdown reversed this protective effect. In summary, our research elucidates that ET prevents ALF advancement by upregulating Sirt1 levels, triggering the Nrf2/HO-1 signaling axis, and suppressing the NF-κB/NLRP3 signaling cascade to inhibit oxidative stress and cell pyroptosis. Our results provide a mechanistic explanation for the protective effect of ET against ALF.

Salidroside promotes the repair of spinal cord injury by inhibiting astrocyte polarization, promoting neural stem cell proliferation and neuronal differentiation

Spinal cord injury (SCI) remains a formidable challenge, lacking effective treatments. Following SCI, neural stem cells (NSCs) migrate to SCI sites, offering a potential avenue for nerve regeneration, but the effectiveness of this intrinsic repair mechanism remains suboptimal. Salidroside has demonstrated pro-repair attributes in various pathological conditions, including arthritis and cerebral ischemia, and the ability to curtail early-stage inflammation following SCI. However, the specific role of salidroside in the late-stage repair processes of SCI remains less defined. In this investigation, we observed that continuous salidroside treatment in SCI mice improved motor function recovery. Immunofluorescence-staining corroborated salidroside's capacity to stimulate nerve regeneration and remyelination, suppress glial scar hyperplasia, reduce the activation of neurotoxic A1 astrocytes, and facilitate NSCs migration towards the injured region. Mechanistically, in vitro experiments elucidated salidroside's significant role in restraining astrocyte proliferation and A1 polarization. It was further established that A1 astrocytes hinder NSCs proliferation while inducing their differentiation into astrocytes. Salidroside effectively ameliorated this inhibition of NSCs proliferation through diminishing c-Jun N-terminal kinase (JNK) pathway phosphorylation and restored their differentiation into neurons by suppressing the signal transducer and activator of transcription 3 (STAT3) pathway. In summary, our findings suggest that salidroside holds promise as a therapeutic agent for traumatic SCI treatment.

Whole transcriptome mapping reveals the lncRNA regulatory network of TFP5 treatment in diabetic nephropathy

BACKGROUND

TFP5 is a Cdk5 inhibitor peptide, which could restore insulin production. However, the role of TFP5 in diabetic nephropathy (DN) is still unclear.

OBJECTIVE

This study aims to characterize the transcriptome profiles of mRNA and lncRNA in TFP5-treated DN mice to mine key lncRNAs associated with TFP5 efficacy.

METHODS

We evaluated the role of TFP5 in DN pathology and performed RNA sequencing in C57BL/6J control mice, C57BL/6J db/db model mice, and TFP5 treatment C57BL/6J db/db model mice. The differentially expressed lncRNAs (DElncRNAs) and mRNAs (DEmRNAs) were analyzed. WGCNA was used to screen hub-gene of TFP5 in treatment of DN.

RESULTS

Our results showed that TFP5 therapy ameliorated renal tubular injury in DN mice. In addition, compared with the control group, the expression profile of lncRNAs in the model group was significantly disordered, while TFP5 alleviated the abnormal expression of lncRNAs. A total of 67 DElncRNAs shared among the three groups, 39 DElncRNAs showed a trend of increasing in the DN group and decreasing after TFP treatment, while the remaining 28 showed the opposite trend. DElncRNAs were enriched in glycosphingolipid biosynthesis signaling pathways, NF-κB signaling pathways, and complement activation signaling pathways. There were 1028 up-regulated and 1117 down-regulated DEmRNAs in the model group compared to control group, and 123 up-regulated and 153 down-regulated DEmRNAs in the TFP5 group compared to the model group. The DEmRNAs were involved in PPAR and MAPK signaling pathway. We confirmed that MSTRG.28304.1 is a key DElncRNA for TFP5 treatment of DN. TFP5 ameliorated DN maybe by inhibiting MSTRG.28304.1 through regulating the insulin resistance and PPAR signaling pathway. The qRT-PCR results confirmed the reliability of the sequencing data through verifying the expression of ENSMUST00000211209, MSTRG.31814.5, MSTRG.28304.1, and MSTRG.45642.14.

CONCLUSION

Overall, the present study provides novel insights into molecular mechanisms of TFP5 treatment in DN.

Salvianolic acid B attenuates diabetic nephropathy through alleviating ADORA2B, NALP3 in flammasome, and NFκB activity

Diabetic nephropathy is one of the microvascular complications of diabetes. This study is aimed at investigating the role and mechanisms of salvianolic acid B (Sal B) in diabetic nephropathy. High glucose (HG)-induced human renal tubular epithelial HK-2 cells were treated with Sal B, BAY-60-6583 (agonist of adenosine 2B receptor), or PSB-603 (antagonist of adenosine 2B receptor) for 24 h. Adenosine A2b receptor (ADORA2B), NACHT, leucine-rich repeat (LRR), and pyrin (PYD) domains-containing protein 3 (NALP3), and nuclear factor Kappa B (NFκB) expressions, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) levels were examined. Following 6 weeks of Sal B treatment, db/db mice blood and kidney tissue were harvested for biochemical detection with hematoxylin-eosin (H&E), Masson's, periodic acid schiff (PAS), and Sirius red staining and detection of ADORA2B, NALP3, NFκB, interleukin 1β (IL-1β), and toll-like receptor 4 (TLR4) activity. NFκB, NALP3, and ADORA2B were found to be downregulated in Sal B treated HK-2 cells exposed to high glucose (HG), accompanied by elevated levels of MMPs and reduced intracellular ROS production. Sal B-treated diabetic mice had the improvement in body weight, water intake, hyperglycemia, hyperlipidemia, and liver and kidney function. Altogether, Sal B attenuates HG-induced kidney tubule cell injury and diabetic nephropathy in diabetic mice, providing clues to other novel mechanisms by which Sal B is beneficial in diabetic nephropathy.

Roles of Sirt1 and its modulators in diabetic microangiopathy: A review

Diabetic vascular complications include diabetic macroangiopathy and diabetic microangiopathy. Diabetic microangiopathy is characterised by impaired microvascular endothelial function, basement membrane thickening, and microthrombosis, which may promote renal, ocular, cardiac, and peripheral system damage in diabetic patients. Therefore, new preventive and therapeutic strategies are urgently required. Sirt1, a member of the nicotinamide adenine dinucleotide-dependent histone deacetylase class III family, regulates different organ growth and development, oxidative stress, mitochondrial function, metabolism, inflammation, and aging. Sirt1 is downregulated in vascular injury and microangiopathy. Moreover, its expression and distribution in different organs correlate with age and play critical regulatory roles in oxidative stress and inflammation. This review introduces the background of diabetic microangiopathy and the main functions of Sirt1. Then, the relationship between Sirt1 and different diabetic microangiopathies and the regulatory roles mediated by different cells are described. Finally, we summarize the modulators that target Sirt1 to ameliorate diabetic microangiopathy as an essential preventive and therapeutic measure for diabetic microangiopathy. In conclusion, targeting Sirt1 may be a new therapeutic strategy for diabetic microangiopathy.

IL-17 induces NSCLC cell migration and invasion by elevating MMP19 gene transcription and expression through the interaction of p300-dependent STAT3-K631 acetylation and its Y705-phosphorylation

The cancer cell metastasis is a major death reason for patients with non-small cell lung cancer (NSCLC). Although researchers have disclosed that interleukin 17 (IL-17) can increase matrix metalloproteinases (MMPs) induction causing NSCLC cell metastasis, the underlying mechanism remains unclear. In the study, we found that IL-17 receptor A (IL-17RA), p300, p-STAT3, Ack-STAT3, and MMP19 were up-regulated both in NSCLC tissues and NSCLC cells stimulated with IL-17. p300, STAT3 and MMP19 overexpression or knockdown could raise or reduce IL-17-induced p-STAT3, Ack-STAT3 and MMP19 level as well as the cell migration and invasion. Mechanism investigation revealed that STAT3 and p300 bound to the same region (-544 to -389 nt) of MMP19 promoter, and p300 could acetylate STAT3-K631 elevating STAT3 transcriptional activity, p-STAT3 or MMP19 expression and the cell mobility exposed to IL-17. Meanwhile, p300-mediated STAT3-K631 acetylation and its Y705-phosphorylation could interact, synergistically facilitating MMP19 gene transcription and enhancing cell migration and invasion. Besides, the animal experiments exhibited that the nude mice inoculated with NSCLC cells by silencing p300, STAT3 or MMP19 gene plus IL-17 treatment, the nodule number, and MMP19, Ack-STAT3, or p-STAT3 production in the lung metastatic nodules were all alleviated. Collectively, these outcomes uncover that IL-17-triggered NSCLC metastasis involves up-regulating MMP19 expression via the interaction of STAT3-K631 acetylation by p300 and its Y705-phosphorylation, which provides a new mechanistic insight and potential strategy for NSCLC metastasis and therapy.

Sirtuins in kidney diseases: potential mechanism and therapeutic targets

Sirtuins, which are NAD+-dependent class III histone deacetylases, are involved in various biological processes, including DNA damage repair, immune inflammation, oxidative stress, mitochondrial homeostasis, autophagy, and apoptosis. Sirtuins are essential regulators of cellular function and organismal health. Increasing evidence suggests that the development of age-related diseases, including kidney diseases, is associated with aberrant expression of sirtuins, and that regulation of sirtuins expression and activity can effectively improve kidney function and delay the progression of kidney disease. In this review, we summarise current studies highlighting the role of sirtuins in renal diseases. First, we discuss sirtuin family members and their main mechanisms of action. We then outline the possible roles of sirtuins in various cell types in kidney diseases. Finally, we summarise the compounds that activate or inhibit sirtuin activity and that consequently ameliorate renal diseases. In conclusion, targeted modulation of sirtuins is a potential therapeutic strategy for kidney diseases. Video Abstract.

ASH2L-mediated H3K4me3 drives diabetic nephropathy through HIPK2 and Notch1 pathway

Diabetic nephropathy (DN) is one of the complications of diabetes. Long-term hyperglycemia in the kidney results in renal insufficiency, and eventually leads to end-stage renal disease. Epigenetic factor ASH2L has long been identified as a transcriptional activator, and we previously indicated that ASH2L aggravated fibrosis and inflammation in high glucose-induced glomerular mesangial cells, but the pathophysiological relevance and the mechanism of ASH2L-mediated H3K4me3 in DN is not well understood. Here we demonstrated that ASH2L is upregulated in glomeruli isolated from db/db mice. Loss of ASH2L protected glomerular injury caused by hyperglycemia, as evidenced by reduced albuminuria, preserved structure, decreased glomerular extracellular matrix deposition, and lowered renal glomerular expression of proinflammatory and profibrotic markers in db/db mice. Furthermore, we demonstrated that enrichment of ASH2L-mediated H3K4me3 on the promoter regions of ADAM17 and HIPK2 triggered their transcription, leading to aberrant activation of Notch1 signaling pathway, thereby contributing to fibrosis and inflammation in DN. The findings of this study provide compelling evidence for targeting ASH2L as a potential therapeutic strategy to prevent or slow down the progression of DN.

Hyaluronic Acid-Based Reactive Oxygen Species-Responsive Multifunctional Injectable Hydrogel Platform Accelerating Diabetic Wound Healing

Diabetic wounds are more likely to develop into complex and severe chronic wounds. The objective of this study is to develop and assess a reactive oxygen species (ROS)-responsive multifunctional injectable hydrogel for the purpose of diabetic wound healing. A multifunctional hydrogel (HA@Cur@Ag) is successfully synthesized with dual antioxidant, antibacterial, and anti-inflammatory properties by crosslinking thiol hyaluronic acid (SH-HA) and disulfide-bonded hyperbranched polyethylene glycol (HB-PBHE) through Michael addition; while, incorporating curcumin liposomes and silver nanoparticles (AgNPs). The HA@Cur@Ag hydrogel exhibits favorable biocompatibility, degradability, and injectivity. The outcomes of in vitro and in vivo experiments demonstrate that the hydrogel can effectively be loaded with and release curcumin liposomes, as well as silver ions, thereby facilitating diabetic wound healing through multiple mechanisms, including ROS scavenging, bactericidal activity, anti-inflammatory effects, and the promotion of angiogenesis. Transcriptome sequencing reveals that the HA@Cur@Ag hydrogel effectively suppresses the activation of the tumour necrosis factor (TNF)/nuclear factor κB (NF-κB) pathway to ameliorate oxidative stress and inflammation in diabetic wounds. These findings suggest that this ROS-responsive multifunctional injectable hydrogel, which possesses the ability to precisely coordinate and integrate intricate biological and molecular processes involved in wound healing, exhibits notable potential for expediting diabetic wound healing.

Acute Kidney Injury Caused by Rhabdomyolysis Is Ameliorated by Serum Albumin-Based Supersulfide Donors through Antioxidative Pathways

Oxidative stress is responsible for the onset and progression of various kinds of diseases including rhabdomyolysis-induced acute kidney injury (AKI). Antioxidants are, therefore, thought to aid in the recovery of illnesses linked to oxidative stress. Supersulfide species have been shown to have substantial antioxidative activity; however, due to their limited bioavailability, few supersulfide donors have had their actions evaluated in vivo. In this study, human serum albumin (HSA) and N-acetyl-L-cysteine polysulfides (NACSn), which have polysulfides in an oxidized form, were conjugated to create a supersulfide donor. HSA is chosen to be a carrier of NACSn because of its extended blood circulation and high level of biocompatibility. In contrast to a supersulfide donor containing reduced polysulfide in HSA, the NACSn-conjugated HSAs exhibited stronger antioxidant activity than HSA and free NACSn without being uptaken by the cells in vitro. The supersulfide donor reduced the levels of blood urea nitrogen and serum creatinine significantly in a mouse model of rhabdomyolysis-induced AKI. Supersulfide donors significantly reduced the expression of oxidative stress markers in the kidney. These results indicate that the developed supersulfide donor has the therapeutic effect on rhabdomyolysis-induced AKI.

Anti-Aging Drugs and the Related Signal Pathways

Aging is a multifactorial biological process involving chronic diseases that manifest from the molecular level to the systemic level. From its inception to 31 May 2022, this study searched the PubMed, Web of Science, EBSCO, and Cochrane library databases to identify relevant research from 15,983 articles. Multiple approaches have been employed to combat aging, such as dietary restriction (DR), exercise, exchanging circulating factors, gene therapy, and anti-aging drugs. Among them, anti-aging drugs are advantageous in their ease of adherence and wide prevalence. Despite a shared functional output of aging alleviation, the current anti-aging drugs target different signal pathways that frequently cross-talk with each other. At present, six important signal pathways were identified as being critical in the aging process, including pathways for the mechanistic target of rapamycin (mTOR), AMP-activated protein kinase (AMPK), nutrient signal pathway, silent information regulator factor 2-related enzyme 1 (SIRT1), regulation of telomere length and glycogen synthase kinase-3 (GSK-3), and energy metabolism. These signal pathways could be targeted by many anti-aging drugs, with the corresponding representatives of rapamycin, metformin, acarbose, nicotinamide adenine dinucleotide (NAD+), lithium, and nonsteroidal anti-inflammatory drugs (NSAIDs), respectively. This review summarized these important aging-related signal pathways and their representative targeting drugs in attempts to obtain insights into and promote the development of mechanism-based anti-aging strategies.

Zinc finger protein 831 promotes apoptosis and enhances chemosensitivity in breast cancer by acting as a novel transcriptional repressor targeting the STAT3/Bcl2 signaling pathway

Emerging evidence suggested that zinc finger protein 831 (ZNF831) was associated with immune activity and stem cell regulation in breast cancer. Whereas, the roles and molecular mechanisms of ZNF831 in oncogenesis remain unclear. ZNF831 expression was significantly diminished in breast cancer which was associated with promoter CpG methylation but not mutation. Ectopic over-expression of ZNF831 suppressed breast cancer cell proliferation and colony formation and promoted apoptosis in vitro, while knockdown of ZNF831 resulted in an opposite phenotype. Anti-proliferation effect of ZNF831 was verified in vivo. Bioinformatic analysis of public databases and transcriptome sequencing both showed that ZNF831 could enhance apoptosis through transcriptional regulation of the JAK/STAT pathway. ChIP and luciferase report assays demonstrated that ZNF831 could directly bind to one specific region of STAT3 promoter and induce the transcriptional inhibition of STAT3. As a result, the attenuation of STAT3 led to a restraint of the transcription of Bcl2 and thus accelerated the apoptotic progression. Augmentation of STAT3 diminished the apoptosis-promoting effect of ZNF831 in breast cancer cell lines. Furthermore, ZNF831 could ameliorate the anti-proliferation effect of capecitabine and gemcitabine in breast cancer cell lines. Our findings demonstrate for the first time that ZNF831 is a novel transcriptional suppressor through inhibiting the expression of STAT3/Bcl2 and promoting the apoptosis process in breast cancer, suggesting ZNF831 as a novel biomarker and potential therapeutic target for breast cancer patients.

Quantitative Proteomics Combined with Network Pharmacology Analysis Unveils the Biological Basis of Schisandrin B in Treating Diabetic Nephropathy

BACKGROUND

Diabetic nephropathy (DN) is a major complication of diabetes. Schisandrin B (Sch) is a natural pharmaceutical monomer that was shown to prevent kidney damage caused by diabetes and restore its function. However, there is still a lack of comprehensive and systematic understanding of the mechanism of Sch treatment in DN.

OBJECTIVE

We aim to provide a systematic overview of the mechanisms of Sch in multiple pathways to treat DN in rats.

METHODS

Streptozocin was used to build a DN rat model, which was further treated with Sch. The possible mechanism of Sch protective effects against DN was predicted using network pharmacology and was verified by quantitative proteomics analysis.

RESULTS

High dose Sch treatment significantly downregulated fasting blood glucose, creatinine, blood urea nitrogen, and urinary protein levels and reduced collagen deposition in the glomeruli and tubule-interstitium of DN rats. The activities of superoxide dismutase (SOD) and plasma glutathione peroxidase (GSH-Px) in the kidney of DN rats significantly increased with Sch treatment. In addition, the levels of IL-6, IL-1β, and TNF-α were significantly reduced in DN rats treated with Sch. 11 proteins that target both Sch and DN were enriched in pathways such as MAPK signaling, PI3K-Akt signaling, renal cell carcinoma, gap junction, endocrine resistance, and TNF signaling. Furthermore, quantitative proteomics showed that Xaf1 was downregulated in the model vs. control group and upregulated in the Sch-treated vs. model group. Five proteins, Crb3, Tspan4, Wdr45, Zfp512, and Tmigd1, were found to be upregulated in the model vs. control group and downregulated in the Sch vs. model group. Three intersected proteins between the network pharmacology prediction and proteomics results, Crb3, Xaf1, and Tspan4, were identified.

CONCLUSION

Sch functions by relieving oxidative stress and the inflammatory response by regulating Crb3, Xaf1, and Tspan4 protein expression levels to treat DN disease.

Research progress of natural active compounds on improving podocyte function to reduce proteinuria in diabetic kidney disease

Diabetic kidney disease (DKD) is a primary cause of end-stage renal disease. Proteinuria is a clinical indicator of the different stages of DKD, and podocyte injury is a major cause of proteinuria. Podocyte-specific proteins (PSPs) play important roles in the normal filtration of podocytes. Studies have shown that natural active compounds (NACs) can ameliorate proteinuria; however, the mechanism related to PSPs needs to be explored. In this study, the five stages of DKD related to proteinuria and the functions of PSPs are displayed separately. Mechanisms for ameliorating proteinuria and improving the PSPs of the 15 NACs are summarized. The in vitro and in vivo mechanistic research showed that five compounds, astragaloside IV, ligustrazine, berberine, emodin and resveratrol, exerted renal protective effects via AMPK signaling, icariin and berberine via TLR4 signaling, hirudin and baicalin via MAPK signaling, curcumin and baicalin via NF-κB signaling, and emodin via protein kinase RNA-like endoplasmic reticulum kinase signaling. The 13 PSPs were divided into five categories: actin cytoskeleton, basal domain, apical domain, slit diaphragm, and others. In conclusion, anti-inflammatory effects, anti-oxidative stress, and enhanced autophagy are the main mechanisms underlying the ameliorative effects of NACs. Podocyte apoptosis is mainly related to nephrin and podocin, which are the most studied slit diaphragm PSPs.

Curcumenol improves renal function in 5/6 nephrectomy-induced chronic renal failure rats via the SIRT1/NF-κB pathway

The present work aimed to explore the protective effects of curcumenol and evaluate its pharmacological mechanisms in 5/6 nephrectomy-induced chronic renal failure (CRF). Rats with CRF were administrated curcumenol and the effects on renal functions were investigated. Renal function examinations were carried out, whereas serum levels of inflammatory mediators, including NF-κB, MCP-1 and IL-1β were analyzed by ELISA. The mRNA expression levels of SIRT1, p65 and IκBα were measured by qRT-PCR, and the SIRT1 protein levels were analyzed by western blot and immunohistochemistry. Our results indicated that curcumenol significantly improved the renal functions in the CRF rats. Compared to the sham group, serum levels of NF-κB, MCP-1, IL-1β, and the mRNA expression levels of p65 were significantly increased (p < 0.01), whereas the mRNA expression level of IκBα was significantly decreased (p < 0.01) and the SIRT1 levels were dramatically down-regulated (p < 0.05) in the CRF groups. Treatment with curcumenol remarkably inhibited inflammatory responses as reflected by the reduced levels of inflammatory mediators (p < 0.01) and SIRT1 up-regulation (p < 0.05). Our findings suggested that curcumenol could improve the renal function in 5/6 nephrectomy-induced CRF rats, and the mechanisms might involve suppressing the associated inflammation and modulating the SIRT1 and NF-κB signaling pathways.

Inhibition of MD2 by natural product-drived JM-9 attenuates renal inflammation and diabetic nephropathy in mice

Diabetic kidney disease (DKD) is one of the severe complications of diabetes mellitus-related microvascular lesions, which remains the leading cause of end-stage kidney disease. The genesis and development of DKD is closely related to inflammation. Myeloid differentiation 2 (MD2) mediates hyperlyciemia-induced renal inflammation and DKD development and is considered as a potential therapeutic target of DKD. Here, we identified a new small-molecule MD2 inhibitor, JM-9. In vitro, JM-9 suppressed high glucose (HG) and palmitic acid (PA)-induced inflammation in MPMs, accompanied by inhibition of MD2 activation and the downstream TLR4/MyD88-MAPKs/NFκB pro-inflammatory signaling pathway. Macrophage-derived factors increased the fibrotic and inflammatory responses in renal tubular epithelial cells, which were inhibited by treating macrophages with JM-9. Then, we investigated the therapeutic effects against DKD in streptozotocin-induced type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) mouse models. Treatment with JM-9 prevented renal inflammation, fibrosis, and dysfunction by targeting MD2 in both T1DM and T2DM models. Our results show that JM-9, a new small-molecule MD2 inhibitor, protects against DKD by targeting MD2 and inhibiting MD2-mediated inflammation. In summary, JM-9 is a potential therapeutic agent for DKD.

Elevated circulating inflammatory biomarker levels in the SIRT1-NF-κB-sCD40L pathway in patients with acute myocardial infarction: a case-control study

BACKGROUND

Inflammation plays a key role in atherosclerosis development and progression. However, the role of novel inflammatory biomarker pathways, namely the SIRT1-NF-κB-sCD40L, in the etiopathogenesis of human atherosclerosis remains undefined. This study was designed to evaluate the changes and clinical implications of these inflammatory mediators in the plasma of patients with acute myocardial infarction (AMI).

METHODS

The peripheral arterial blood of 88 participants (68 patients with AMI and 20 age-matched controls), was drawn prior to performing coronary angiography (CAG). The SIRT1, NF-κB, and sCD40L plasma levels were quantified using ELISA. Spearman's analysis was used to evaluate the correlation between the three inflammatory markers, while Pearson's test assessed their potential correlation with cardiac troponin T (TNT) levels. Sensitivity, specificity, and area under the ROC curve (AUC) were calculated as measures of diagnostic accuracy.

RESULTS

Patients with AMI showed higher levels of circulating SIRT1, NF-κB, and sCD40L compared to the age-matched controls (p < 0.05). However, the plasma concentrations of these three inflammatory mediators did not differ between the ST-segment elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI) patients. Additionally, in patients with AMI, the SIRT1 level was positively correlated with NF-κB and sCD40L levels (p < 0.001). Likewise, the levels of SIRT1, NF-κB and sCD40L were positively correlated with TNT levels (p < 0.001). More importantly, the ROC analysis showed that the diagnostic accuracy of AMI was significantly higher when NF-κB or sCD40L level was used in combination with TNT levels (p < 0.05).

CONCLUSIONS

The levels of the circulating inflammatory biomarkers, including SIRT1, NF-κB, and sCD40L, were significantly elevated in patients with AMI. These novel biomarkers can improve the diagnostic accuracy of AMI when combined with TNT.KEY MESSAGESAMI is a potentially lethal CAD and is the leading cause of mortality and morbidity worldwide. Inflammation plays a key role in atherosclerosis development and progression. The levels of the circulating novel inflammatory biomarkers, including SIRT1, NF-κB, and sCD40L, were significantly elevated in patients with AMI.The SIRT1 level was positively correlated with NF-κB and sCD40L levels in patients with AMI.The levels of SIRT1, NF-κB and sCD40L were positively correlated with TNT levels.The ROC analysis showed that the diagnostic accuracy of AMI was significantly higher when NF-κB or sCD40L level was used in combination with TNT levels.SIRT1/NF-κB/sCD40L axis inhibition is a potential new target for AMI treatment.

Protein Persulfidation: Recent Progress and Future Directions

Significance: Hydrogen sulfide (H2S) is considered to be a gasotransmitter along with carbon monoxide (CO) and nitric oxide (NO), and is known as a key regulator of physiological and pathological activities. S-sulfhydration (also known as persulfidation), a mechanism involving the formation of protein persulfides by modification of cysteine residues, is proposed here to explain the multiple biological functions of H2S. Investigating the properties of protein persulfides can provide a foundation for further understanding of the potential functions of H2S. Recent Advances: Multiple methods have been developed to determine the level of protein persulfides. It has been demonstrated that protein persulfidation is involved in many biological processes through various mechanisms including the regulation of ion channels, enzymes, and transcription factors, as well as influencing protein-protein interactions. Critical Issues: Some technical and theoretical questions remain to be solved. These include how to improve the specificity of the detection methods for protein persulfidation, why persulfidation typically occurs on one or a few thiols within a protein, how this modification alters protein functions, and whether protein persulfidation has organ-specific patterns. Future Directions: Optimizing the detection methods and elucidating the properties and molecular functions of protein persulfidation would be beneficial for current therapeutics. In this review, we introduce the detailed mechanism of the persulfidation process and discuss persulfidation detection methods. In addition, this review summarizes recent discoveries of the selectivity of protein persulfidation and the regulation of protein functions and cell signaling pathways by persulfidation. Antioxid. Redox Signal. 39, 829-852.

Protein acetylation and related potential therapeutic strategies in kidney disease

Kidney disease can be caused by various internal and external factors that have led to a continual increase in global deaths. Current treatment methods can alleviate but do not markedly prevent disease development. Further research on kidney disease has revealed the crucial function of epigenetics, especially acetylation, in the pathology and physiology of the kidney. Histone acetyltransferases (HATs), histone deacetylases (HDACs), and acetyllysine readers jointly regulate acetylation, thus affecting kidney physiological homoeostasis. Recent studies have shown that acetylation improves mechanisms and pathways involved in various types of nephropathy. The discovery and application of novel inhibitors and activators have further confirmed the important role of acetylation. In this review, we provide insights into the physiological process of acetylation and summarise its specific mechanisms and potential therapeutic effects on renal pathology.

Acetylation in pathogenesis: Revealing emerging mechanisms and therapeutic prospects

Protein acetylation modifications play a central and pivotal role in a myriad of biological processes, spanning cellular metabolism, proliferation, differentiation, apoptosis, and beyond, by effectively reshaping protein structure and function. The metabolic state of cells is intricately connected to epigenetic modifications, which in turn influence chromatin status and gene expression patterns. Notably, pathological alterations in protein acetylation modifications are frequently observed in diseases such as metabolic syndrome, cardiovascular disorders, and cancer. Such abnormalities can result in altered protein properties and loss of function, which are closely associated with developing and progressing related diseases. In recent years, the advancement of precision medicine has highlighted the potential value of protein acetylation in disease diagnosis, treatment, and prevention. This review includes provocative and thought-provoking papers outlining recent breakthroughs in acetylation modifications as they relate to cardiovascular disease, mitochondrial metabolic regulation, liver health, neurological health, obesity, diabetes, and cancer. Additionally, it covers the molecular mechanisms and research challenges in understanding the role of acetylation in disease regulation. By summarizing novel targets and prognostic markers for the treatment of related diseases, we aim to contribute to the field. Furthermore, we discuss current hot topics in acetylation research related to health regulation, including N4-acetylcytidine and liquid-liquid phase separation. The primary objective of this review is to provide insights into the functional diversity and underlying mechanisms by which acetylation regulates proteins in disease contexts.

Melatonin attenuates cellular senescence and apoptosis in diabetic nephropathy by regulating STAT3 phosphorylation

AIMS

Melatonin is an endogenous hormone related to the regulation of biorhythm. Previous researchers have found that melatonin can ameliorate diabetic nephropathy (DN), but the mechanism remains to be elucidated. To discover the possible mechanism by which melatonin prevents DN, we investigated the potential effects of melatonin on signal transducer and activator of transcription 3 (STAT3) on the progression of cellular senescence and apoptosis.

MAIN METHODS

Cellular senescence, apoptosis and the underlying mechanism of melatonin were investigated both in vivo and in vitro. C57BL/6 mice were intraperitoneally injected with streptozotocin (STZ) to establish DN. For an in vitro model of DN, human renal cortex proximal epithelial tubule (HK-2) cells were exposed to high glucose conditions.

KEY FINDINGS

Melatonin inhibited the phosphorylation of STAT3, decreased the expression of senescence proteins p53, p21 and p16INK4A. Melatonin also downregulated the expression of apoptotic proteins, including cleaved PARP1, cleaved caspase-9 and -3. Melatonin treatment decreased the positive area of senescence-associated galactosidase (SA-β-gal) staining and the number of TUNEL-positive cells in kidneys of DN mice. In vitro, melatonin inhibited STAT3 phosphorylation and lowered cellular senescence and apoptosis markers, in a manner similar to the STAT3 inhibitor S3I-201. In addition, the inhibition effect of melatonin on cellular senescence and apoptosis in HK-2 cells was reversed by the usage of recombinant IL-6 (rIL-6), which can induce STAT3 phosphorylation.

SIGNIFICANCE

We, for the first time, demonstrate that melatonin inhibits STAT3 phosphorylation, which is involved in alleviating the cellular senescence and apoptosis in DN.

Therapeutic application of traditional Chinese medicine in kidney disease: Sirtuins as potential targets

Sirtuins are a family of NAD+ III-dependent histone deacetylases that consists of seven family members, Sirt1-Sirt7, which regulate various signalling pathways and are involved in many critical biological processes of kidney diseases. Traditional Chinese medicine (TCM), as an essential part of the global healthcare system, has multi-component and multi-pathway therapeutic characteristics and plays a role in preventing and controlling various diseases. Through ongoing collaboration with modern medicine, TCM has recently achieved many remarkable advancements in theoretical investigation, mechanistic research, and clinical applications related to kidney diseases. Therefore, a comprehensive and systematic summary of TCM that focuses on sirtuins as the intervention target for kidney diseases is necessary. This review introduces the relationship between abnormal sirtuins levels and common kidney diseases, such as diabetic kidney disease and acute kidney injury. Based on the standard biological processes, such as inflammation, oxidative stress, autophagy, mitochondrial homeostasis, and fibrosis, which are underlying kidney diseases, comprehensively describes the roles and regulatory effects of TCM targeting the sirtuins family in various kidney diseases.

Sweroside plays a role in mitigating high glucose-induced damage in human renal tubular epithelial HK-2 cells by regulating the SIRT1/NF-κB signaling pathway

Sweroside is a natural monoterpene derived from Swertia pseudochinensis Hara. Recently, studies have shown that sweroside exhibits a variety of biological activities, such as anti-inflammatory, antioxidant, and hypoglycemic effects. However, its role and mechanisms in high glucose (HG)-induced renal injury remain unclear. Herein, we established a renal injury model in vitro by inducing human renal tubular epithelial cell (HK-2 cells) injury by HG. Then, the effects of sweroside on HK-2 cell activity, inflammation, reactive oxygen species (ROS) production, and epithelial mesenchymal transition (EMT) were observed. As a result, sweroside treatment ameliorated the viability, inhibited the secretion of inflammatory cytokines (TNF-α, IL-1β, and VCAM-1), reduced the generation of ROS, and inhibited EMT in HK-2 cells. Moreover, the protein expression of SIRT1 was increased and the acetylation of p65 NF-kB was decreased in HK-2 cells with sweroside treatment. More importantly, EX527, an inhibitor of SIRT1, that inactivated SIRT1, abolished the improvement effects of sweroside on HK-2 cells. Our findings suggested that sweroside may mitigate HG-caused injury in HK-2 cells by promoting SIRT1-mediated deacetylation of p65 NF-kB.

Common mechanisms underlying diabetic vascular complications: focus on the interaction of metabolic disorders, immuno-inflammation, and endothelial dysfunction

Diabetic vascular complications (DVCs), including macro- and micro- angiopathy, account for a high percentage of mortality in patients with diabetes mellitus (DM). Endothelial dysfunction is the initial and role step for the pathogenesis of DVCs. Hyperglycemia and lipid metabolism disorders contribute to endothelial dysfunction via direct injury of metabolism products, crosstalk between immunity and inflammation, as well as related interaction network. Although physiological and phenotypic differences support their specified changes in different targeted organs, there are still several common mechanisms underlying DVCs. Also, inhibitors of these common mechanisms may decrease the incidence of DVCs effectively. Thus, this review may provide new insights into the possible measures for the secondary prevention of DM. And we discussed the current limitations of those present preventive measures in DVCs research. Video Abstract.

Activated SIRT1 contributes to DPT-induced glioma cell parthanatos by upregulation of NOX2 and NAT10

Parthanatos is a type of programmed cell death dependent on hyper-activation of poly (ADP-ribose) polymerase 1 (PARP-1). SIRT1 is a highly conserved nuclear deacetylase and often acts as an inhibitor of parthanatos by deacetylation of PARP1. Our previous study showed that deoxypodophyllotoxin (DPT), a natural compound isolated from the traditional herb Anthriscus sylvestris, triggered glioma cell death via parthanatos. In this study, we investigated the role of SIRT1 in DPT-induced human glioma cell parthanatos. We showed that DPT (450 nmol/L) activated both PARP1 and SIRT1, and induced parthanatos in U87 and U251 glioma cells. Activation of SIRT1 with SRT2183 (10 μmol/L) enhanced, while inhibition of SIRT1 with EX527 (200 μmol/L) or knockdown of SIRT1 attenuated DPT-induced PARP1 activation and glioma cell death. We demonstrated that DPT (450 nmol/L) significantly decreased intracellular NAD+ levels in U87 and U251 cells. Further decrease of NAD+ levels with FK866 (100 μmol/L) aggravated, but supplement of NAD+ (0.5, 2 mmol/L) attenuated DPT-induced PARP1 activation. We found that NAD+ depletion enhanced PARP1 activation via two ways: one was aggravating ROS-dependent DNA DSBs by upregulation of NADPH oxidase 2 (NOX2); the other was reinforcing PARP1 acetylation via increase of N-acetyltransferase 10 (NAT10) expression. We found that SIRT1 activity was improved when being phosphorylated by JNK at Ser27, the activated SIRT1 in reverse aggravated JNK activation via upregulating ROS-related ASK1 signaling, thus forming a positive feedback between JNK and SIRT1. Taken together, SIRT1 activated by JNK contributed to DPT-induced human glioma cell parthanatos via initiation of NAD+ depletion-dependent upregulation of NOX2 and NAT10.

Resveratrol inhibits ferroptosis and decelerates heart failure progression via Sirt1/p53 pathway activation

Resveratrol is an organic compound widely studied for its therapeutic uses. We investigated whether resveratrol exerts cardioprotective effects by inhibiting ferroptosis via the Sirt1/p53 pathway. A heart failure model was established by aortic coarctation in Sirt1 knockout mice. The superoxide dismutase (SOD), glutathione (GSH) levels and mitochondrial morphology in murine heart tissues were assessed at different time points to determine the role of ferroptosis in heart failure progression. The cardiac function of mice with heart failure was evaluated by determining the brain natriuretic peptide (BNP) and sST2 concentration and conducting echocardiography. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were transfected with the p53 K382R mutant and Sirt1 interference lentiviral vectors. Immunoprecipitation (IP) experiments were performed to investigate whether Sirt1 influences ferroptosis via p53 K382 acetylation and SLC7A11 expression modulation. Resveratrol improved cardiac function in mice and decelerated ferroptosis and fibrosis progression in heart failure. However, the ability of resveratrol to prevent ferroptosis and treat heart failure was lost after silencing Sirt1. Sirt1 reduced ferroptosis by diminishing the levels of p53 K382 acetylation, reducing the degradation of SLC7A11, and increasing the levels of GSH and glutathione peroxidase 4 (GPX4) in cells. In conclusion, by activating the Sirt1/p53 pathway in heart failure, resveratrol decreased the depletion of SLC7A11, inhibited ferroptosis, and improved cardiac function.

Fraxin represses NF-κB pathway via inhibiting the activation of epidermal growth factor receptor to ameliorate diabetic renal tubulointerstitial fibrosis

Renal tubulointerstitial fibrosis (RIF), featured by epithelial-to-mesenchymal-transition (EMT) of renal tubular epithelial cells and collagen deposition in the renal interstitial region, is the main pathological change of diabetic nephropathy (DN). Fraxin, the main active component of Fraxinus rhynchophylla Hance with anti-inflammatory activity, has been demonstrated to ameliorate glomerulosclerosis. However, the regulatory role of Fraxin on diabetic RIF remains unclear. In this study, we investigated the renal protective benefits of Fraxin against diabetic RIF and elucidated its mechanisms. In vitro, Fraxin inhibited the abnormal expression of EMT-related markers and proinflammatory cytokines, improved cellular morphology, and subsequently reduced the extracellular matrix (ECM) production in high glucose (HG)-induced NRK-52E cells. In vivo, Fraxin effectively ameliorated renal function, inhibited the abnormal expression of EMT-related markers and proinflammatory cytokines, and reduced ECM deposition in renal tubule interstitium in db/db mice. Notably, Fraxin could directly bind to epidermal growth factor receptor (EGFR), which contributed to the inhibition of EGFR phosphorylation and counteracted the activation of c-Src/NF-κB pathway, eventually ameliorating RIF. Thus, Fraxin may be a potential drug candidate for treating DN.

Novel insights into STAT3 in renal diseases

Signal transducer and activator of transcription 3 (STAT3) is a cell-signal transcription factor that has attracted considerable attention in recent years. The stimulation of cytokines and growth factors can result in the transcription of a wide range of genes that are crucial for several cellular biological processes involved in pro- and anti-inflammatory responses. STAT3 has attracted considerable interest as a result of a recent upsurge in study because of their role in directing the innate immune response and sustaining inflammatory pathways, which is a key feature in the pathogenesis of many diseases, including renal disorders. Several pathological conditions which may involve STAT3 include diabetic nephropathy, acute kidney injury, lupus nephritis, polycystic kidney disease, and renal cell carcinoma. STAT3 is expressed in various renal tissues under these pathological conditions. To better understand the role of STAT3 in the kidney and provide a theoretical foundation for STAT3-targeted therapy for renal disorders, this review covers the current work on the activities of STAT3 and its mechanisms in the pathophysiological processes of various types of renal diseases.

Celastrol attenuates diabetic nephropathy by upregulating SIRT1-mediated inhibition of EZH2related wnt/β-catenin signaling

Proteinuria is an independent risk factor for the progression of diabetic nephropathy (DN) and an imbalance in podocyte function aggravates proteinuria. Celastrol is the primary active ingredient of T. wilfordii, effective in treating DN renal injury; however, the mechanisms underlying its effect are unclear. We explored how celastrol prevents DN podocyte damage using in vivo and in vitro experiments. We randomly divided 24 male C57BLKS/J mice into three groups: db/m (n = 8), db/db (n = 8), and celastrol groups (db/db + celastrol, 1 mg/kg/d, gavage administration, n = 8). In vivo experiments lasted 12 weeks and intervention lasted ten weeks. Serum samples and kidney tissues were collected for biochemical tests, pathological staining, transmission electron microscopy, fluorescencequantitation polymerase chain reaction, and western blotting analysis. In vitro experiments to elaborate the mechanism of celastrol protection were performed on high glucose (HG)-induced podocyte injury. Celastrol reduced blood glucose levels and renal function index in db/db mice, attenuated renal histomorphological injury and glomerular podocyte foot injuries, and induced significant anti-inflammatory effects. Celastrol upregulated silent information regulator 2 related enzyme 1(SIRT1) expression and downregulated enhancer of zeste homolog (EZH2), inhibiting the wnt/β-catenin pathway-related molecules, such as wnt1, wnt7a, and β-catenin. SIRT1 repressed the promoter activity of EZH2, and was co-immunoprecipitated with EZH2 in mouse podocyte cells (MPC5). SIRT1 knockdown aggravated the protective effects of celastrol on MPC5 cells. Celastrol protected podocyte injury via SIRT1/EZH2, which participates in the wnt/β-catenin pathway. Overall, celastrol-mediated SIRT1 upregulation inhibited the EZH2-related wnt/β-catenin signaling pathway to attenuate DN and podocyte injury, providing a theoretical basis for celastrol clinical application.

Metformin suppresses cardiac fibroblast proliferation under high-glucose conditions via regulating the mitochondrial complex I protein Grim-19 involved in the Sirt1/Stat3 signaling pathway

Hyperglycemia associated with myocardial oxidative stress and fibrosis is the main cause of diabetic cardiomyopathy. Currently, no approved drug is available for preventing or treating diabetes-induced cardiac fibrosis. Metformin has been reported to improve glycemic control and ameliorate diabetic cardiomyopathy. This study aimed to investigate the effects and mechanism of metformin on diabetes-induced cardiac fibrosis and high glucose-induced proliferation of cardiac fibroblasts (CFs). In this study, db/db mice were treated with metformin [250 mg/kg⋅d, gavage]. CFs were cultured in high-glucose medium to mimic an in vitro diabetes model and then subjected to treatment with or without metformin. Cardiac fibrosis was analyzed using immunohistochemistry, Masson's trichrome staining, and Western blot analysis. Cell Counting Kit-8 (CCK-8) assays and cell colony formation assays were used to examine cell proliferation capacity. Transwell and scratch-wound assays were used to detect the migration ability of CFs. Retinoid-interferon-induced mortality-19 (Grim-19), sirtuin1 (Sirt1), and signal transducer and activator of transcription 3 (Stat3) were detected using Western blot analysis. The genes downstream of the Stat3 pathway were detected using quantitative reverse transcription PCR (qRT‒PCR). Metformin treatment markedly attenuated cardiac fibrosis in db/db mice and the proliferation and migration of CFs under high-glucose conditions. Mechanistically, we found an intersection between metformin and Grim-19 using bioinformatics. Metformin was found to suppress the expression of p-Stat3 and elevate the expression of mitochondrial complex I protein Grim-19 and Sirt1, thus inhibiting the proliferation and migration of CFs under high-glucose conditions. Our data suggested that metformin inhibited the proliferation and migration of CFs by regulating the expression of mitochondrial complex I Grim-19 protein involved in the Sirt1/Stat3 signaling pathway under high-glucose conditions, thus providing new ideas for treating diabetes-induced cardiac fibrosis.

Astragaloside IV attenuates high glucose-induced NF-κB-mediated inflammation through activation of PI3K/AKT-ERK-dependent Nrf2/ARE signaling pathway in glomerular mesangial cells

Inflammation is a key contributor to diabetic kidney disease pathogenesis, including reactive oxidation stress (ROS)-mediated nuclear factor-κB (NF-κB) signaling pathway. In this study, we examined the effect of Astragaloside IV (AS-IV) on anti-inflammatory and anti-oxidative properties under high glucose (HG) condition and the potential mechanism in glomerular mesangial cells (GMCs). We showed that AS-IV concentration-dependently reduced GMCs proliferation, restrained ROS release and hydrogen peroxide content, and suppressed pro-inflammatory cytokines as well as pro-fibrotic factors expression, which were associated with the inhibition of NF-κB and nuclear factor-erythroid 2-related factor 2 (Nrf2) signaling activation. Accordingly, both NF-κB overexpression by using RNA plasmid and Nrf2 gene silencing by using RNA interference weakened the ability of AS-IV to ameliorate HG-induced oxidative stress, inflammation, and cell proliferation. Furthermore, phosphatidylinositide 3-kinases (PI3K)/serine/threonine protein kinase (Akt) and extracellular regulated protein kinases (ERK) signaling pathway regulated the process of AS-IV-induced Nrf2 activation and antioxidant capacity, which evidenced by using PI3K inhibitor LY294002 or ERK inhibitor PD98059 that largely abolished the AS-IV efficacy. Taken together, these results indicated that AS-IV protected against HG-induced GMCs damage by inhibiting ROS/NF-kB-induced increases of inflammatory cytokines, fibrosis biomarkers, and cell proliferation via up-regulation of Nrf2-dependent antioxidant enzyme expression, which were mediated by PI3K/Akt and ERK signaling pathway activation.

Salmonella Pullorum effector SteE regulates Th1/Th2 cytokine expression by triggering the STAT3/SOCS3 pathway that suppresses NF-κB activation

Salmonella enterica serovar Pullorum (S. Pullorum) can regulate host immunity via special effectors that promote persistent infection and its intracellular survival. SteE as an anti-inflammatory effector is involved in the systemic infection of Salmonella in host macrophages. Macrophage activation can indirectly reflect the immune regulatory function of T helper type 1 (Th1)/T helper type 2 (Th2) cytokines. However, information concerning the regulation of Th1/Th2 cytokine expression by steE in S. Pullorum infection is limited. This study evaluates the effects of steE on the Th1/Th2 balance, STAT3/SOCS3 pathway, and NF-κB P65 activation in S. Pullorum-infected HD-11 cells and in chicken models. We demonstrated that steE diminished the expression of Th1-related cytokines (IFN-γ and IL-12) and promoted the expression of Th2-related cytokines (IL-4 and IL-10) in HD-11 cells and chicken models of S. Pullorum infection. SOCS3 silencing suppressed the function of steE in HD-11 cells and led to the imbalance of Th1/Th2-related cytokines. SteE promoted SOCS3 expression by activating STAT3 in HD-11 cells. Moreover, steE inhibited NF-κB P65 expression and blocked its translocation to the nucleus by promoting SOCS3 expression. Our results illustrated that steE regulated the expression of Th1/Th2 cytokines via modulation of the STAT3/SOCS3 and NF-κB axis, which might be associated with Th1/Th2 cell differentiation and could, therefore, be a novel therapeutic strategy against salmonellosis.

Identifying cellular senescence associated genes involved in the progression of end-stage renal disease as new biomarkers

BACKGROUND

Cellular senescence plays an essential role in the development and progression of end-stage renal disease (ESRD). However, the detailed mechanisms phenomenon remains unclear.

METHODS

The mRNA expression profiling dataset GSE37171 was taken from the Gene Expression Omnibus (GEO) database. The cell senescence-associated hub genes were selected by applying protein-protein interaction (PPI), followed by correlation analysis, gene interaction analysis, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. We next explored the relationships of hub genes with miRNAs, TFs, and diseases. The absolute abundance of eight immune cells and two stromal cells were calculated by MCPcount and the correlation of hub genes with these ten cells was analyzed. Lasso was used to selecting for trait genes. ROC curves and DCA decision curves were used to assess the accuracy and predictive power of the trait genes.

RESULTS

A total of 65 cellular senescence signature genes were identified among patients and controls. The PPI network screened out ten hub genes. GO and KEGG indicated that ten hub genes were associated with ESRD progression. Transcription factor gene interactions and common regulatory networks of miRNAs were also identified in the datasets. The hub genes were significantly correlated with immune cells and stromal cells. Then the lasso model was constructed to screen out the five most relevant signature genes (FOS, FOXO3, SIRT1, TP53, SMARCA4). The area under the ROC curve (AUC) showed that these five characteristic genes have good resolving power for the diagnostic model.

CONCLUSIONS

Our findings suggested that cellular senescence-associated genes played an important role in the development of ESRD and immune regulation.

Glycyrrhizic Acid Protects Glomerular Podocytes Induced by High Glucose by Modulating SNARK/AMPK Signaling Pathway

OBJECTIVE

Diabetic nephropathy is one of the most important microvascular complications of diabetes, which mainly refers to glomerular capillary sclerosis. Podocytes are an important part of glomerular capillaries. Previous clinical and basic studies have shown that fibrosis is the main factor of diabetic nephropathy. This study aimed to assess the protective mechanism of glycyrrhizic acid (GA) on glomerular podocytes induced by high glucose as we hypothesized that GA may have antifibrotic and anti-inflammatory effects on podocytes through regulation of the adenosine 5'-monophosphate-activated protein kinase (AMPK)/sucrose nonfermenting AMPK-related kinase (SNARK) signaling pathway.

METHODS

SNARK siRNA was used to transfect podocytes. Real-time quantitative polymerase chain reaction and immunofluorescence staining assays were used for molecular and pathological analysis. The expression levels of key pathway proteins (including TGF-β1, α-SMA, SITR1, AMPKα, LKB1, PGC-1α, NF-κB, IL-6, and TNF-α) were verified by Western blotting. The expression of inflammatory factors in podocytes was detected by ELISA.

RESULTS

We demonstrated that GA decreased the expression of podocyte fibrosis signaling pathway-related factors by upregulating the AMPK pathway and its related factors. However, after transfection of podocytes with SNARK siRNA, there was an increased expression of fibrosis-related factors and inflammation-related factors.

CONCLUSION

GA can protect podocytes and alleviate fibrosis and inflammation induced by high glucose, which is related to the AMPK signaling pathway. Meanwhile, knockdown of SNARK protein can inhibit the AMPK signaling pathway, aggravate fibrosis, and increase inflammation.

Oxidative stress and inflammation in diabetic nephropathy: role of polyphenols

Diabetic nephropathy (DN) often leads to end-stage renal disease. Oxidative stress demonstrates a crucial act in the onset and progression of DN, which triggers various pathological processes while promoting the activation of inflammation and forming a vicious oxidative stress-inflammation cycle that induces podocyte injury, extracellular matrix accumulation, glomerulosclerosis, epithelial-mesenchymal transition, renal tubular atrophy, and proteinuria. Conventional treatments for DN have limited efficacy. Polyphenols, as antioxidants, are widely used in DN with multiple targets and fewer adverse effects. This review reveals the oxidative stress and oxidative stress-associated inflammation in DN that led to pathological damage to renal cells, including podocytes, endothelial cells, mesangial cells, and renal tubular epithelial cells. It demonstrates the potent antioxidant and anti-inflammatory properties by targeting Nrf2, SIRT1, HMGB1, NF-κB, and NLRP3 of polyphenols, including quercetin, resveratrol, curcumin, and phenolic acid. However, there remains a long way to a comprehensive understanding of molecular mechanisms and applications for the clinical therapy of polyphenols.

NAD+ metabolism-based immunoregulation and therapeutic potential

Nicotinamide adenine dinucleotide (NAD⁺) is a critical metabolite that acts as a cofactor in energy metabolism, and serves as a cosubstrate for non-redox NAD⁺-dependent enzymes, including sirtuins, CD38 and poly(ADP-ribose) polymerases. NAD⁺ metabolism can regulate functionality attributes of innate and adaptive immune cells and contribute to inflammatory responses. Thus, the manipulation of NAD⁺ bioavailability can reshape the courses of immunological diseases. Here, we review the basics of NAD⁺ biochemistry and its roles in the immune response, and discuss current challenges and the future translational potential of NAD⁺ research in the development of therapeutics for inflammatory diseases, such as COVID-19.

Sirt1 Overexpression Inhibits Fibrous Scar Formation and Improves Functional Recovery After Cerebral Ischemic Injury Through the Deacetylation of 14-3-3ζ

Cerebral ischemic stroke is one of the leading causes of human death. The fibrous scar is one of major factors influencing repair in central nervous system (CNS) injury. Silencing information regulator 2-related enzyme 1 (Sirt1) can regulate peripheral tissue and organ fibrosis. However, it is unclear how the fibrous scar forms and is regulated and it is unknown whether and how Sirt1 regulates the formation of the fibrous scar after cerebral ischemic stroke. Therefore, in the present study, we examined the effects of Sirt1 on the formation of the fibrotic scar after middle cerebral artery occlusion/reperfusion (MCAO/R) injury in vivo and on the transforming growth factor β1 (TGF-β1)-induced meningeal fibroblast fibrotic response in vitro, and we explored the molecular mechanisms underlying the Sirt1-regulated fibrosis process in vitro. We found that MCAO/R injury induced fibrotic scar formation in the ischemic area, which was accompanied by the downregulation of Sirt1 expression. The overexpression of Sirt1 reduced the infarct volume, improved Nissl body structure and reduced neurons injury, attenuated formation of fibrotic scar, upregulated growth associated protein43 (GAP43) and synaptophysin (SYP) expression, and promoted neurological function recovery. Similarly, Sirt1 expression was also downregulated in the TGF-β1-induced fibrosis model. Sirt1 overexpression inhibited fibroblast migration, proliferation, transdifferentiation into myofibroblasts, and secretion of extracellular matrix(ECM) by regulating the deacetylation of lysine at K49 and K120 sites of 14-3-3ζ in vitro. Therefore, we believe that Sirt1 could regulate fibrous scar formation and improve neurological function after cerebral ischemic stroke through regulating deacetylation of 14-3-3ζ.

The combination of Alisma and Atractylodes ameliorates cerebral ischaemia/reperfusion injury by negatively regulating astrocyte-derived exosomal miR-200a-3p/141-3p by targeting SIRT1

ETHNOPHARMACOLOGICAL RELEVANCE

The combination of Alisma and Atractylodes (AA), a classical traditional Chinese herbal decoction, may protect against cerebral ischaemia/reperfusion injury (CIRI). However, the underlying mechanism has not been characterized. Intriguingly, exosomal microRNAs (miRNAs) have been recognized as vital factors in the pharmacology of Chinese herbal decoctions.

AIM OF THE STUDY

The aim of the present study was to assess whether the neuroprotective effect of AA was dependent on the efficient transfer of miRNAs via exosomes in the brain.

MATERIALS AND METHODS

Bilateral common carotid artery ligation (BCAL) was used to induce transient global cerebral ischaemia/reperfusion (GCI/R) in C57BL/6 mice treated with/without AA. Neurological deficits were assessed with the modified neurological severity score (mNSS) and Morris water maze (MWM) test. Western blot (WB) analysis was used to detect the expression of sirtuin 1 (SIRT1) in the cerebral cortex. The inflammatory state was quantitatively evaluated by measuring the expression of phospho-Nuclear factor kappa B (p-NF-κB), Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) using WB analysis and glial fibrillary acidic protein (GFAP) immunohistochemical staining. The protein expression of zonula occluden-1 (ZO-1), occludin, caudin-5 and CD31 was examined by immunohistochemical staining to determine blood‒brain barrier (BBB) permeability. Exosomes were extracted from the brain interstitial space by ultracentrifugation and identified by transmission electron microscopy (TEM), WB analysis and nanoparticle tracking analysis (NTA). The origin of exosomes was clarified by measuring the specific mRNAs within exosomes via Real Time Quantitative PCR (RT‒qPCR). Differential miRNAs in exosomes were identified using microarray screening and were validated by RT‒qPCR. Exosomes were labelled with fluorescent dye (PKH26) and incubated with bEnd.3 cells, the supernatant was collected, IL-1β/TNF-α expression was measured using enzyme-linked immunosorbent assay (ELISA), total RNA was extracted, and miR-200a-3p/141-3p expression was examined by RT‒qPCR. In addition, the levels of miR-200a-3p/141-3p in oxygen glucose deprivation/reoxygenation (OGD/R)-induced bEnd.3 cells were quantified. The direct interaction between miR-200a-3p/141-3p and the SIRT1 3' untranslated region (3'UTR) was measured by determining SIRT1 expression in bEnd.3 cells transfected with the miR-200a-3p/141-3p mimic/inhibitor.

RESULTS

Severe neurological deficits and memory loss caused by GCI/R in mice was markedly ameliorated by AA treatment, particularly in the AA medium-dose group. Moreover, AA-treated GCI/R-induced mice showed significant increases in SIRT1, ZO-1, occludin, caudin-5, and CD31 expression levels and decreases in p-NF-κB, IL-1β, TNF-α, and GFAP expression levels compared with those in untreated GCI/R-induced mice. Furthermore, we found that miR-200a-3p/141-3p was enriched in astrocyte-derived exosomes from GCI/R-induced mice and could be inhibited by treatment with a medium dose of AA. The exosomes mediated the transfer of miR-200a-3p/141-3p into bEnd.3 cells, promoted IL-1β and TNF-α release and downregulated the expression of SIRT1. No significant changes in the levels of miR-200a-3p/141-3p were observed in OGD/R-induced bEnd.3 cells. The miR-200a-3p/141-3p mimic/inhibitor decreased/increased SIRT1 expression in bEnd.3 cells, respectively.

CONCLUSION

Our findings demonstrated that AA attenuated inflammation-mediated CIRI by inhibiting astrocyte-derived exosomal miR-200a-3p/141-3p by targeting the SIRT1 gene, which provided further evidence and identified a novel regulatory mechanism for the neuroprotective effects of AA.

Nicaraven protects against endotoxemia-induced inflammation and organ injury through modulation of AMPK/Sirt1 signaling in macrophages

Endotoxemia is a disease characterized by systemic inflammatory responses and organ injury caused by lipopolysaccharide (LPS) infection, with high mortality. Nicaraven (AVS), a potent hydroxyl radical scavenger, has been proven to regulate the inflammatory response in tumors. To investigate the protective effects and mechanisms of AVS in endotoxemia, mice were injected intraperitoneally with LPS to induce endotoxemia. AVS treatment significantly decreased the levels of pro-inflammatory cytokines in the serum, reduced neutrophil infiltration, attenuated multiple organ injury, and increased the survival rate in LPS-challenged mice. In the LPS-induced inflammatory model of macrophages, AVS inhibited macrophage activation, suppressed nitric oxide (NO) production, and inhibited the expression and secretion of pro-inflammatory cytokines. Mechanistically, AVS treatment up-regulated silence information regulator transcript-1 (Sirt1) expression in a time- and dose-dependent manner. AVS treatment activated the AMP-dependent protein kinase (AMPK)/Sirt1 signaling pathway and suppressed the activation of nuclear factor kappa B (NF-κB) in macrophages exposed to LPS. However, the anti-inflammatory effects of AVS could be reversed by the AMPK, the Sirt1 inhibitor, or the histone deacetylase inhibitor. We confirmed that the AMPK inhibitor inhibited AVS-mediated AMPK/Sirt1 activation and NF-κB p65 acetylation. These results suggested that AVS alleviated endotoxemia by activating the AMPK/Sirt1 signaling pathway in macrophages.

Kidney fibrosis: from mechanisms to therapeutic medicines

Chronic kidney disease (CKD) is estimated to affect 10-14% of global population. Kidney fibrosis, characterized by excessive extracellular matrix deposition leading to scarring, is a hallmark manifestation in different progressive CKD; However, at present no antifibrotic therapies against CKD exist. Kidney fibrosis is identified by tubule atrophy, interstitial chronic inflammation and fibrogenesis, glomerulosclerosis, and vascular rarefaction. Fibrotic niche, where organ fibrosis initiates, is a complex interplay between injured parenchyma (like tubular cells) and multiple non-parenchymal cell lineages (immune and mesenchymal cells) located spatially within scarring areas. Although the mechanisms of kidney fibrosis are complicated due to the kinds of cells involved, with the help of single-cell technology, many key questions have been explored, such as what kind of renal tubules are profibrotic, where myofibroblasts originate, which immune cells are involved, and how cells communicate with each other. In addition, genetics and epigenetics are deeper mechanisms that regulate kidney fibrosis. And the reversible nature of epigenetic changes including DNA methylation, RNA interference, and chromatin remodeling, gives an opportunity to stop or reverse kidney fibrosis by therapeutic strategies. More marketed (e.g., RAS blockage, SGLT2 inhibitors) have been developed to delay CKD progression in recent years. Furthermore, a better understanding of renal fibrosis is also favored to discover biomarkers of fibrotic injury. In the review, we update recent advances in the mechanism of renal fibrosis and summarize novel biomarkers and antifibrotic treatment for CKD.

Deacetylation of Septin4 by SIRT2 (Silent Mating Type Information Regulation 2 Homolog-2) Mitigates Damaging of Hypertensive Nephropathy

BACKGROUND

Hypertension can lead to podocyte damage and subsequent apoptosis, eventually resulting in glomerulosclerosis. Although alleviating podocyte apoptosis has clinical significance for the treatment of hypertensive nephropathy, an effective therapeutic target has not yet been identified. The function of septin4, a proapoptotic protein and an important marker of organ damage, is regulated by post-translational modification. However, the exact role of septin4 in regulating podocyte apoptosis and its connection to hypertensive renal damage remains unclear.

METHODS

We investigated the function and mechanism of septin4 in hypertensive nephropathy to discover a theoretical basis for targeted treatment. Mouse models including Rosa 26 (Gt(ROSA)26Sor)-SIRT2 (silent mating type information regulation 2 homolog-2)-Flag-TG (transgenic) (SIRT2-TG) mice SIRT2-knockout, and septin4-K174Q mutant mice, combined with proteomic and acetyl proteomics analysis, followed by multiple molecular biological methodologies, were used to demonstrate mechanisms of SIRT2-mediated deacetylation of septin4-K174 in hypertensive nephropathy.

RESULTS

Using transgenic septin4-K174Q mutant mice treated with the antioxidant Tempol, we found that hyperacetylation of the K174 site of septin4 exacerbates Ang II (angiotensin II)- induced hypertensive renal injury resulting from oxidative stress. Proteomics and Western blotting assays indicated that septin4-K174Q activates the cleaved-PARP1 (poly [ADP-ribose] polymerase family, member 1)-cleaved-caspase3 pathway. In septin4-knockdown human renal podocytes, septin4-K174R, which mimics deacetylation at K174, rescues podocyte apoptosis induced by Ang II. Immunoprecipitation and mass spectrometry analyses identified SIRT2 as a deacetylase that interacts with the septin4 GTPase domain and deacetylates septin4-K174. In Sirt2-deficient mice and SIRT2-knockdown renal podocytes, septin4-K174 remains hyperacetylated and exacerbates hypertensive renal injury. By contrast, in Rosa26-Sirt2-Flag (SIRT2-TG) mice and SIRT2-knockdown renal podocytes reexpressing wild-type SIRT2, septin4-K174 is hypoacetylated and mitigates hypertensive renal injury.

CONCLUSIONS

Septin4, when activated through acetylation of K174 (K174Q), promotes hypertensive renal injury. Septin4-K174R, which mimics deacetylation by SIRT2, inhibits the cleaved-PARP1-cleaved-caspase3 pathway. Septin4-K174R acts as a renal protective factor, mitigating Ang II-induced hypertensive renal injury. These findings indicate that septin4-K174 is a potential therapeutic target for the treatment of hypertensive renal injury.

Protein persulfidation: Rewiring the hydrogen sulfide signaling in cell stress response

The past few decades have witnessed significant progress in the discovery of hydrogen sulfide (H₂S) as a ubiquitous gaseous signaling molecule in mammalian physiology, akin to nitric oxide and carbon monoxide. As the third gasotransmitter, H₂S is now known to exert a wide range of physiological and cytoprotective functions in the biological systems. However, endogenous H₂S concentrations are usually low, and its potential biologic mechanisms responsible have not yet been fully clarified. Recently, a growing body of evidence has demonstrated that protein persulfidation, a posttranslational modification of cysteine residues (RSH) to persulfides (RSSH) elicited by H₂S, is a fundamental mechanism of H₂S-mediated signaling pathways. Persulfidation, as a biological switch for protein function, plays an important role in the maintenance of cell homeostasis in response to various internal and external stress stimuli and is also implicated in numerous diseases, such as cardiovascular and neurodegenerative diseases and cancer. In this review, the biological significance of protein persulfidation by H₂S in cell stress response is reviewed providing a framework for understanding the multifaceted roles of H₂S. A mechanism-guided perspective can help open novel avenues for the exploitation of therapeutics based on H₂S-induced persulfidation in the context of diseases.

Forkhead box A2-mediated lncRNA SOX2OT up-regulation alleviates oxidative stress and apoptosis of renal tubular epithelial cells by promoting SIRT1 expression in diabetic nephropathy

BACKGROUND

Renal tubular injury is the main feature of diabetic nephropathy (DN). We intend to investigate the function and related mechanisms of lncRNA SOX2 overlapping transcript (SOX2OT) in high glucose (HG)-induced oxidative stress and apoptosis of renal tubular epithelial cells (RTECs).

METHODS

To construct diabetes models, the human kidney-2 (HK-2) cells were treated with HG (30 mM), and mice were injected with streptozotocin. The levels of intracellular and mitochondrial reactive oxygen species (ROS) were assessed by dihydroethidium staining and MitoSox staining. The cell apoptosis was assessed by flow cytometry and TUNEL staining. Levels of serum creatinine, blood urea nitrogen (BUN), Urinary ACR, and oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) were detected by relevant kits. In addition, fluorescence in situ hybridization staining, RNA-pull down, RNA immunoprecipitation (RIP), co-immunoprecipitation (co-IP), dual-luciferase reporter gene assay and chromatin immunoprecipitation (ChIP) were also executed.

RESULTS

Levels of SOX2OT and silent information regulator 1 (SIRT1) were down-regulated in HG-cultured HK-2 cells. Overexpressing SOX2OT reduced intracellular and mitochondrial ROS levels and cell apoptosis in vitro. Moreover, SOX2OT overexpression also reduced serum creatinine, BUN, urinary ACR, 8-OHdG, renal tubular injury markers KIM1 and NGAL, ROS levels, and cell apoptosis in vivo. In addition, SOX2OT promoted SIRT1 expression by suppressing its ubiquitination. Besides, interference with SIRT1 reversed the inhibitory effect of SOX2OT overexpression on HG-induced oxidative stress and apoptosis. Forkhead box A2 (Foxa2) levels were up-regulated in HG-cultured HK-2 cells. Foxa2 could bind to the SOX2OT promoter and suppress its expression. Furthermore, interfering with SOX2OT reversed the inhibitory effect of Foxa2 interference on HG-induced oxidative stress and apoptosis.

CONCLUSION

Foxa2-mediated SOX2OT up-regulation reduced oxidative stress and apoptosis of RTECs by promoting SIRT1 expression, thus alleviating the progression of DN.