Acute kidney injury (AKI) is a severe clinical condition with high morbidity and mortality. Caveolin-1 (Cav-1), a main structural protein of caveolae, orchestrates key cellular processes including endocytosis, lipid transport, and signal transduction by serving as a platform. However, its specific role in AKI remains unclear. Here, we report that Cav-1 is upregulated in distal tubule epithelial cells (TECs) in both AKI patients and mouse models induced by ischemia/reperfusion injury (IRI) and lipopolysaccharide (LPS). Global and distal TEC-specific Cav1 knockout exacerbates IRI and LPS-induced AKI. RNA-seq reveals that Cav-1 deficiency exacerbates intracellular calcium ion (Ca2+) homeostasis imbalance and endoplasmic reticulum (ER) stress in injured kidney tissues. Mechanistically, Cav-1 interacts with sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 2 (SERCA2), a key regulator of intracellular Ca2+ homeostasis, through its scaffolding domain, promoting SERCA2 deubiquitination and stability in the ER, thereby maintaining intracellular Ca2+ homeostasis and suppressing ER stress in distal TECs. Furthermore, supplementation with a cell-permeable Cav-1 scaffolding domain peptide (CSP) or activation of SERCA2 with a small-molecule agonist CDN1163 alleviates IRI- and LPS-induced AKI, while distal TEC-specific SERCA2 knockdown abrogates CSP's therapeutic effect. Together, these findings reveal a novel Cav-1-mediated pathway and highlight its potential as a therapeutic target for AKI.

Chronic kidney disease is associated with high incidence and mortality rates and has emerged as a major global public health challenge. However, effective therapeutic strategies to improve patient survival remain limited. Ferroptosis, a regulated form of cell death driven by irondependent lipid peroxidation, has recently emerged as a key contributor to the pathogenesis and progression of chronic kidney disease. Owing to its high mitochondrial density and intense metabolic activity, the kidney is particularly vulnerable to ferroptosis. Accumulating evidence indicates that ferroptosis-mediated cellular damage promotes renal functional decline, whereas ferroptosis inhibitors and iron chelators confer renoprotection across multiple experimental models, highlighting ferroptosis as a promising therapeutic target in kidney diseases. Despite growing interest, the precise pathogenic mechanisms of ferroptosis in the kidney remain incompletely understood. To advance mechanistic insights and therapeutic development, this review summarizes the key molecular events associated with iron overload and lipid peroxidation, as well as their crosstalk with pro-fibrotic and pro-inflammatory signaling pathways. We highlight major regulatory factors, including TFR1, GPX4, FSP1, CHAC1, Nrf2, DHODH, and NLRP3, alongside recent advances in small-molecule modulators targeting these pathways. We also discuss newly identified ferroptosis-related biomarkers that may serve as potential diagnostic or therapeutic indicators. Overall, ferroptosis represents a promising therapeutic avenue for CKD; further studies are required to elucidate its regulatory networks and facilitate clinical translation.

Ferroptosis is a regulated form of cell death driven by iron-dependent lipid peroxidation. Emerging evidence implicates ferroptosis in the pathogenesis of various kidney diseases by inducing death in renal tubular epithelial cells (RTECs), podocytes, mesangial cells (MCs), and endothelial cells (ECs), which exhibit distinct structural and functional traits that might determine their differential susceptibility to ferroptosis. Despite its importance, the precise mechanism of ferroptosis in kidney pathology remains unclear, limiting its therapeutic potential and drug development. Understanding cell type-specific ferroptosis mechanisms and their spatial distribution in kidney diseases could provide novel insights for renal protection. In this review, we summarize current knowledge regarding ferroptosis susceptibility in different renal cell types to bridge cellular and organ-level perspectives for potential translational applications.

Pulmonary arterial hypertension (PAH) is a progressive, high-mortality disease with multifactorial pathology. Although current therapies primarily target vascular remodeling, single-pathway approaches often remain insufficient against its complex pathogenesis. Ferroptosis, an iron-dependent lipid peroxidation-driven cell death, is intrinsically linked to core PAH features, such as oxidative stress, endothelial dysfunction, and inflammation. Therefore, inhibiting ferroptosis presents a promising therapeutic strategy by simultaneously counteracting these key pathological drivers. Here, we provide a detailed review of the latest research progress on ferroptosis inhibitors, elucidate their molecular mechanisms in PAH, highlight their pathogenic significance, and discuss the associated challenges and opportunities, providing insights for novel PAH treatment development.

INTRODUCTION:Cellular calcium homeostasis is essential for maintaining kidney function. Sarcoplasmic/endoplasmic reticulum calcium ATPase 2 (SERCA2), the primary calcium pump responsible for transporting cytosolic calcium ions back into the endoplasmic reticulum, is a key regulator of endoplasmic reticulum stress and intracellular calcium balance. However, its specific role in acute kidney injury (AKI) and the underlying regulatory mechanisms remain poorly understood. METHODS:SERCA2 expression was measured in biopsies of patients with AKI, animal models, and cellular assays. AKI models were established using SERCA2 conditional knockdown and overexpression mice, HK-2 cells and primary kidney tubular epithelial cells in vitro. To investigate the underlying mechanisms, we integrated approaches including RNA-sequencing, transmission electron microscopy, immunofluorescence, and Seahorse analyses. RESULTS:Transcriptomic and histopathological analyses revealed reduced SERCA2 expression in proximal tubules of both patient AKI biopsies and murine models. Proximal tubule-specific SERCA2 knockdown exacerbated kidney dysfunction and tubular injury in murine AKI, while SERCA2 allosteric activation with CDN1163 or its overexpression attenuated these injuries. Mechanistically, SERCA2 deficiency disrupted endoplasmic reticulum calcium homeostasis, leading to endoplasmic reticulum stress and promoting voltage dependent anion channel 1 (VDAC1) oligomerization through impaired mitochondria-associated endoplasmic reticulum membranes. These changes led to mitochondrial permeability transition pore opening, mitochondrial calcium overload, oxidative stress, and ferroptosis. Importantly, stopping VDAC1 oligomerization with small molecule inhibitor VBIT-4 or blocking ferroptosis with ferrostatin-1 restored mitochondrial function and mitigated ferroptosis in SERCA2-deficient models. CONCLUSIONS:Our study identifies the SERCA2-VDAC1 axis as a critical regulator of endoplasmic reticulum-mitochondrial calcium homeostasis in AKI. Both SERCA2 activation and inhibition of VDAC1 oligomerization conferred substantial renoprotection, highlighting this pathway as a promising therapeutic target for attenuating tubular damage in AKI.

Based on two key pathological features of pulmonary arterial hypertension (PAH), elevated pulmonary artery pressure and vascular remodeling, two new series of nitric oxide (NO) donating lenumlostat derivatives were designed, synthesized, and biologically evaluated. The results indicated that compound LNO 9 exhibited LOXL2 inhibitory activity comparable to lenumlostat, remarkably suppressing hypoxia-induced collagen oxidation and aberrant collagen cross-linking. Furthermore, LNO 9 effectively released NO and increased 3',5'-cyclic guanosine monophosphate in HPASMCs, thereby exerting a potent vasodilation. In both hypoxia- and MCT-induced rat models of PAH, LNO 9 significantly improved right ventricular hypertrophy and pulmonary arterial medial wall thickness. Meanwhile, LNO 9 demonstrated superior efficacy in reducing right ventricular systolic pressure compared to lenumlostat. In short, the present study has demonstrated unequivocally that a therapeutic approach for PAH that combines NO donors for vasodilation with extracellular matrix inhibitors to suppress vascular remodeling represents a promising treatment.

Aberrant succinate accumulation functions as a potent metabolic danger signal in various inflammatory diseases. However, the specific contribution of the succinate-GPR91 signaling axis to the pathogenesis of renal fibrosis remains incompletely defined. Succinate levels were analyzed in kidney tissues from patients with obstructive nephropathy and mice with unilateral ureteral obstruction (UUO). The impact of succinate on renal fibrosis was evaluated using exogenous succinate administration and pharmacological inhibition with dimethyl malonate (DMM). Mechanistic studies employed Gpr91-knockout mice, NLRP3-knockout mice, and cultured macrophages to dissect the downstream signaling pathways linking metabolic alterations to innate immunity. We observed significantly elevated succinate levels in fibrotic kidneys from both patients and UUO mice, which correlated positively with disease severity. Functionally, exogenous succinate markedly exacerbated renal inflammation and fibrosis, whereas pharmacological inhibition with DMM attenuated these pathological changes. Mechanistically, we demonstrated that succinate mainly activates its receptor GPR91 on macrophages to trigger NLRP3 inflammasome assembly and IL-1β secretion, a pro-fibrotic cascade effectively abolished by genetic ablation of Gpr91 or NLRP3 in vivo, or by their pharmacological blockade in vitro. This study establishes the succinate-GPR91 axis as a pivotal metabolic driver of renal fibrosis, likely primarily through macrophage-mediated NLRP3 inflammasome activation. Targeting this pathway represents a promising therapeutic strategy for interfering with the progression of chronic kidney disease.

Chronic kidney disease (CKD) remains a major global health burden, and renal fibrosis is a key pathological driver of CKD progression. Homeodomain-interacting protein kinase 2 (HIPK2) has emerged as a potential therapeutic target because of its involvement in TGF-β/Smad3-mediated fibrotic signaling and NF-κB-driven inflammatory responses. In this study, a series of 2, 4-disubstituted pyrimidine derivatives were designed and synthesized as HIPK2 inhibitors. Among them, A6 (AF-1) and B11 (AF-2) exhibited potent HIPK2 inhibitory activity, with IC50 values of 0.36 and 0.56 μM, respectively, together with improved subtype selectivity over HIPK1 and HIPK3. Cellular thermal shift assays showed that AF-1 and AF-2 increased the thermal stability of endogenous HIPK2 in both NRK-49F and HK-2 cells, supporting intracellular target engagement. In TGF-β1-stimulated NRK-49F cells and HK-2 cells, both compounds reduced the expression of fibrosis-related markers, including fibronectin, collagen I, and α-SMA. AF-1 and AF-2 also inhibited the proliferation and migration of NRK-49F cells and attenuated TNF-α-induced NF-κB activation in HK-2 cells. In a 0.2% adenine-diet-induced mouse model of CKD, AF-1 and AF-2 alleviated renal tubular injury and collagen deposition, demonstrating significant renoprotective and antifibrotic effects in vivo. Collectively, AF-1 and AF-2 represent antifibrotic candidates with a new chemical scaffold, submicromolar HIPK2 inhibitory activity, and improved subtype selectivity within the HIPK family. Although further optimization is required to improve their pharmacokinetic and drug-like properties, these findings provide a new structural basis for the development of HIPK2 inhibitors with enhanced HIPK family selectivity for the treatment of CKD-associated renal fibrosis.

Recent studies suggested that disrupting the Hsp110-STAT3 interaction is a promising strategy for treating pulmonary arterial hypertension (PAH). However, the restricted reduction in p-STAT3 required to prevent vascular remodeling limits Hsp110-STAT3 PPI inhibitor development. Our preliminary studies revealed that HDAC6 activation in HPAECs contributes to p-STAT3 upregulation. Subsequently, a series of Hsp110/HDAC6 dual-target inhibitors were rationally designed and synthesized. Structure-activity relationship studies identified 15n as a potent dual-target inhibitor, effectively interrupting the Hsp110-STAT3 interaction and suppressing HDAC6 activity. In vitro, 15n exhibited a synergistic effect in suppressing the STAT3 signaling pathway by concurrently targeting Hsp110 and HDAC6, thereby inhibiting the abnormal proliferation and migration of the HPAECs. In vivo, compared with combination therapy, 15n demonstrated enhanced suppressive effects on vascular remodeling through synchronous regulation of dual targets. In summary, the present study provides novel research insights into developing novel PAH drugs based on antivascular remodeling strategies and offers a promising lead compound.

The dual ASK1/PDK1 inhibitor ZNXY-4c has previously been shown to inhibit the proliferation of human fetal lung fibroblasts (HFL-1), however, its efficacy and mechanism in pulmonary fibrosis remain unclear. In this study, we demonstrated that ZNXY-4c ameliorated lung injury and slowed the progression of pulmonary fibrosis in a bleomycin-induced mouse model. ZNXY-4c inhibited the fibrotic response induced by bleomycin, suppressed the upregulated expression of proteins in ASK1-p38/JNK signaling pathways, and effectively reduced PDK1/Akt phosphorylation. Additionally, our study showed that ZNXY-4c attenuated inflammasome activation and pyroptosis in mice lungs and alveolar macrophage. These findings highlight the therapeutic potential of ZNXY-4c and support its further development as a lead compound for the treatment of Idiopathic Pulmonary Fibrosis.

The 53 kDa serine/threonine protein kinase known as cyclin-dependent kinase 8 (CDK8) controls transcription by attaching itself to mediator complexes or phosphorylating transcription factors. As a crucial protein with dual oncogenic and physiological regulatory roles, CDK8 is frequently overexpressed in colorectal cancer (CRC), breast cancer, melanoma, and other tissues, making it a potential antitumor target. Furthermore, it plays important roles in inflammatory responses, fibrotic processes, and the control of bone metabolism, making it a promising therapeutic target for a variety of disease areas. In recent years, the discovery of CDK8 inhibitors has expanded, and many new, highly selective inhibitors have been proposed as possible treatments for human illnesses. This review outlines the most recent developments in CDK8 inhibitors, focusing on their structural classification, structure-activity connections, binding modalities, kinase selectivity, and cross-disease pharmacological activities. It also addresses development obstacles and optimization techniques for achieving selective CDK8 inhibition, aiming to offer recommendations for the rational design and clinical application of CDK8/19-targeting agents.

Background: Hyperuricemia (HUA) is a metabolic disorder that severely threatens human health. Chronic uric acid (UA) overload promotes the progression of tubulointerstitial fibrosis (TIF), leading to impaired UA excretion. Our previous studies identified HIPK2 inhibitor XRF-1021, which exhibits robust anti-TIF activity and lowers UA levels in vivo. This study aimed to elucidate its UA-lowering mechanism and therapeutic potential for HUA. Methods: Uricase and xanthine oxidase (XOD) assays were performed to assess effects on UA degradation/production. HEK293T cells transiently expressing UA transporters and gene-knockdown rats were used to evaluate transporter inhibition, while HK-2 cells were analyzed by Western blot. Pharmacokinetics were characterized in rats. Efficacy was tested in potassium oxonate-induced acute HUA rats, diet/adenine-induced chronic HUA quails, and adenine-induced mice with HUA secondary to TIF. Maximum tolerated dose and long-term toxicity were assessed in rats. Results: XRF-1021 neither activated uricase nor inhibited XOD, indicating no direct effect on UA catabolism or synthesis. Instead, XRF-1021 inhibited URAT1 and GLUT9, reducing renal UA reabsorption, while sparing OAT3, OAT4, and ABCG2 activity and upregulating OAT3 and NPT4, suggesting minimal risk of disrupting drug or uremic toxin handling. XRF-1021 showed dose-dependent systemic exposure in rats, lowered serum UA, and provided renal protection in vivo. LD50 values were 2345.4 mg/kg (male) and 1078.9 mg/kg (female), with no obvious toxicity after long-term dosing. Conclusions: XRF-1021 lowers UA by inhibiting URAT1 and GLUT9 to enhance renal UA excretion and provides kidney protection, supporting XRF-1021 as a promising candidate for HUA therapy.

AMP-activated protein kinase (AMPK), a heterotrimeric serine-threonine kinase, has been identified as a promising target for regulating vascular remodeling in pulmonary arterial hypertension (PAH) due to its capacity to promote proliferation, autophagy, and anti-apoptosis in pulmonary artery smooth muscle cells (PASMCs). However, research into AMPK inhibitors is very limited. Herein, a virtual screening strategy was employed to identify CHEMBL3780091 as a lead compound for a series of novel AMPK inhibitors by exploring the structure-activity relationship around a specific pyridine-2-one scaffold. Subsequently, the most promising 13a was observed to exhibit excellent AMPK inhibitory activity and favorable anti-proliferative activity against PASMCs through the inhibition of the AMPK signaling pathway in vitro. Moreover, compound 13a significantly reduced right ventricular systolic pressure, attenuated vascular remodeling, and improved right heart function in hypoxia-induced PAH rats in vivo. In conclusion, this study provides a novel and potential lead compound for the study of AMPK inhibitors and a new direction for the development of PAH drugs that focus on improving vascular remodeling.

The heat shock protein (HSP) 110 family has a key role as a unique class of molecular chaperones maintaining cellular proteostasis in eukaryotes. Abnormal activation of Hsp110 has been implicated in several diseases. Given its important role in pathogenesis, Hsp110 has become a novel drug target for disease diagnosis and targeted therapy. Thus, targeting Hsp110 or its interactions with client proteins offers new therapeutic approaches. Recent studies of small-molecule inhibitors that target Hsp110 in vitro and in vivo have yielded encouraging results. In this review, we provide an overview of novel therapeutics targeting Hsp110, mainly inhibitors of protein–protein interactions (PPIs), together with a brief discussion of the relevant challenges, opportunities, and future directions.

Molecular glue degraders (MGDs) have emerged as promising therapeutic agents with substantial clinical potential and growing commercial interest in terms of their pharmaceutical development. Nevertheless, the translation of MGDs into clinical trials remains limited. Recent advances in drug discovery technologies are facilitating a paradigm shift in MGD development, from serendipitous discovery to rational design. Here, we systematically analyze rational MGD discovery strategies, focusing on E3 ligase and target ligand modifications. Furthermore, we highlight cutting-edge technologies and the latest trends in MGD development. Thus, this review provide valuable insights for researchers and could help accelerate the clinical translation of MGDs.

Chronic kidney disease (CKD) represents a major global public health challenge, pathologically characterized by renal fibrosis and frequently accompanied by inflammatory responses. Recent study indicates that homeodomain-interacting protein kinase 2 (HIPK2) is a key regulator of these fibrotic and inflammatory pathways. However, highly effective inhibitors targeting HIPK2 are currently lacking. In this study, we employed a fragment-based drug discovery (FBDD) strategy to develop a novel HIPK2 inhibitor, Hit 2c. Hit 2c demonstrated potent kinase inhibitory activity (IC50 = 0.20 μM) and significant antiproliferative effects (NRK-49F IC50 = 0.29 μM, induced by 10 ng/mL TGF-β). Molecular docking, molecular dynamics simulations, and free energy landscape analysis-revealed a stable binding mode between Hit 2c and HIPK2, in which a hydrogen bond formed with the key residue Lys288 serves as the central factor sustaining high binding affinity. Umbrella sampling further indicated that breaking this hydrogen bond requires a high dissociation energy barrier (3.22 kcal/mol). In vitro, Hit 2c inhibited HIPK2 downstream pathways (p53, TGF-β/Smad3, and NF-κB) and significantly downregulated fibrosis markers (Fn Ⅰ, Collagen Ⅰ, α-SMA) in NRK-49F cells induced by 10 ng/mL TGF-β and inflammatory cytokine IL-6 in HK-2 cells induced by 10 ng/mL TNF-α. In vivo, pharmacodynamic studies showed that oral administration of Hit 2c at 10 mg/kg attenuated renal injury and fibrosis in an adenine-induced mouse CKD model, comparable to the positive control dapagliflozin. Pharmacokinetic analysis revealed a half-life of 4.74 h, Cmax of 426.35 ng/mL, AUC0-∞ of 689.05 h ng/mL, suggesting relatively high clearance and low oral bioavailability (3.92 %). Liver microsome experiments suggested potential first-pass metabolism of Hit 2c. Collectively, Hit 2c represents a novel HIPK2 inhibitor scaffold with effective anti-fibrotic activity in vitro and in vivo, providing a lead compound for the development of HIPK2-targeted therapeutics.

Renal fibrosis, a progressive pathology in chronic kidney disease (CKD), is primarily driven by HIPK2 (homeodomain-interacting protein kinase 2)-mediated activation of the TGF-β/Smad3 and NF-κB signaling pathways, leading to excessive extracellular matrix deposition and inflammation. Current therapeutic strategies targeting HIPK2 show limited efficacy, highlighting the need for more effective inhibitors. We developed compound c4 through rational optimization of the lead compound CHR-6494. This derivative exhibits potent dual activities, with IC50 values of 0.68 ± 0.18 μM for HIPK2 inhibition and 0.15 ± 0.02 μM for anti-proliferative effects in NRK-49F cells. Molecular dynamics simulations confirmed the stable binding of the c4-HIPK2 complex. Functional assays in TGF-β-stimulated NRK-49F cells and TNF-α-stimulated HK-2 cells demonstrated that c4, even at low concentrations, significantly downregulated fibrosis markers (Collagen I, Fibronectin, α-SMA) and inflammatory mediators (p-P65, IL-6), while suppressing fibrotic responses (cell proliferation, migration). These findings establish c4 as a promising HIPK2 kinase inhibitor for developing effective anti-fibrotic therapies targeting HIPK2 in CKD.

Cell division cycle 20 homologue (Cdc20) is an essential mitotic regulator whose overexpression is closely associated with tumorigenesis and poor prognosis in triple-negative breast cancer (TNBC). Targeting Cdc20 has therefore emerged as a promising therapeutic avenue for this aggressive malignancy. In the present study, a receptor-based drug design approach was employed to optimize Apcin analogues as Cdc20 inhibitors. Through a two-step strategy-concept validation followed by structural optimization-we identified compound 14c, which demonstrated remarkable Cdc20 binding affinity (KD: 7.65 mu M), potent antiproliferative effects against MDA-MB231 TNBC cells (IC50: 3.28 mu M), and a favorable selectivity index (4.22 for MCF-7 non-TNBC cells and 7.27 for MCF 10A normal cells). 14c effectively inhibited Cdc20 activity, induced G2/M phase arrest, promoted DNA damage accumulation, and stabilized key substrates such as Cyclin B1 and Bim, leading to enhanced apoptosis and suppression of tumor cell proliferation and migration. In vivo, 14c significantly inhibited tumor growth in an MDA-MB-231 xenograft model with a 90 % tumor inhibition rate and no observable toxicity. These results highlight the potential of 14c as a potent Cdc20 inhibitor, offering a promising therapeutic approach for TNBC.

AMP-activated protein kinase (AMPK) plays a key catalytic role in renal energy metabolism. Its activation confers renoprotection through regulating various downstream pathways. Critically, AMPKα2 activation can exacerbate renal injury by promoting uric acid deposition, highlighting the therapeutic advantage of highly selective AMPKα1 activation for renal ischemia-reperfusion injury (RIRI). Given these considerations, we established an effective screening platform to identify initial hits with AMPKα1 activity. Leveraging these hits, we designed and synthesized a series of thiazolidinedione derivatives as selective AMPKα1 activators. Among these, 22f demonstrated superior in vitro AMPKα1 activity (EC50 = 35.1 ± 1.20 nM) and selectivity (176-fold over AMPKα2), coupled with a significant protective effect in NRK-52E cells subjected to hypoxia-reoxygenation injury. Furthermore, in an RIRI mice model, 22f selectively activated renal AMPKα1, significantly attenuating serum creatinine and blood urea nitrogen levels. Notably, 22f outperformed the comparator 991 in alleviating kidney damage and reducing cellular infiltration. More importantly, our study provided compelling evidence that selective activation of AMPKα1 could effectively protect against RIRI pathogenesis. 22f thus emerged as a promising lead compound for the development of novel anti-RIRI therapeutics offering potent efficacy and improved safety profile.

Reversible protein ubiquitination is a crucial factor in cellular homeostasis, with Ubiquitin-Specific Protease 1 (USP1) serving as a key deubiquitinase involved in DNA damage response (DDR) and repair mechanisms in cancer. While ubiquitin ligases have been extensively studied, research on the reverse process of ubiquitination, particularly the mechanisms involving USP1, remains relatively limited. USP1 is overexpressed in various cancers, influencing tumor initiation and progression by regulating multiple associated proteins. Inhibiting USP1 effectively suppresses tumor proliferation and migration and may help overcome resistance to cisplatin and PARP inhibitors. As a potential synthetic lethal target, USP1 demonstrates significant research potential. This review highlights the biological mechanisms of USP1 in cancer progression, the signaling pathways it regulates, and the latest advancements in USP1 inhibitors, while also analyzing the opportunities and challenges of targeting USP1. By adopting the perspective of "the other side of the coin," this review aims to underscore the crucial yet often overlooked role of the deubiquitinase USP1, contrasting it with the extensively studied ubiquitin ligases, and emphasizing its therapeutic potential in cancer treatment.