Berberrubine Alleviates p-Cresyl Sulfate-Induced Tubular Injury via HNRNPF/NR4A1 ER Stress Axis
核心洞察
Berberrubine (搜索), a berberine derivative, reduced p-cresyl sulfate (搜索)-induced renal tubular injury by targeting the HNRNPF (搜索)/NR4A1 (搜索) endoplasmic reticulum stress (搜索) axis.
The study identifies HNRNPF (搜索) as a previously unrecognized regulator of NR4A1 (搜索)-driven ER stress in proximal tubular cells exposed to the uremic toxin.
Findings position berberrubine (搜索) as a candidate renoprotective agent for chronic kidney disease (搜索), where uremic toxins drive tubular damage and fibrosis.
A berberine derivative, berberrubine (搜索), alleviates renal tubular injury induced by the uremic toxin p-cresyl sulfate (搜索) (PCS) through an axis involving the RNA-binding protein HNRNPF (搜索), the nuclear receptor NR4A1 (搜索) and endoplasmic reticulum (ER) stress, according to a study published in Acta Pharmacologica Sinica.
Chronic kidney disease (搜索) (CKD) represents a major global health burden, and its progression is closely tied to the accumulation of uremic retention solutes. Among these, indoxyl sulfate and p-cresyl sulfate (搜索) have been characterized as uremic toxins with documented toxicity. PCS in particular has been shown to cause renal tubular cell damage by inducing oxidative stress through activation of NADPH oxidase, and to exert pro-inflammatory and cytotoxic actions on human proximal tubular epithelial cells. PCS also promotes insulin resistance associated with CKD and, together with indoxyl sulfate, induces inflammatory gene expression in cultured proximal renal tubular cells.
Endoplasmic Reticulum Stress as a Converging Mechanism
ER stress and the unfolded protein response have emerged as central mechanisms in kidney disease. Albumin induces ER stress and apoptosis in renal proximal tubular cells, and ER stress has been implicated in ischemic and nephrotoxic acute kidney injury. Reviews cited in the study describe ER stress as both a driver and a therapeutic target for kidney disease, and proteostasis in the ER has been proposed as a source of new mechanistic insight in renal pathology. ER-associated biomarkers have also been explored for molecular phenotyping of rare kidney disease.
The orphan nuclear receptor NR4A1 (搜索) (also known as Nur77/TR3) has been repeatedly linked to ER stress and apoptosis. NR4A1 regulates ER stress and induces apoptosis via interaction with TRAPγ, and translocation of TR3/Nur77 to the endoplasmic reticulum participates in ER stress-induced apoptosis. NR4A1 has also been shown to aggravate myocardial ischaemia-reperfusion injury by inhibiting OPA1-mediated mitochondrial fusion, and Nur77 exacerbates PC12 cellular injury in vitro by aggravating mitochondrial impairment and ER stress. Separately, Nur77-mediated epigenetic regulation of glutaminase 1 has been reported to promote hepatic stellate cell senescence and alleviate liver fibrosis.
HNRNPF as a Regulator of Renal Tubular Biology
The heterogeneous nuclear ribonucleoprotein F (HNRNPF (搜索)) has an established role in kidney physiology. HNRNPF and HNRNPK mediate insulin inhibition of renal angiotensinogen gene expression and prevent hypertension and kidney injury in diabetic mice. Overexpression of HNRNPF stimulates renal Ace-2 gene expression and prevents TGF-β1-induced kidney injury in a mouse model of diabetes. Tubular deficiency of HNRNPF elevates systolic blood pressure and induces glycosuria in mice, and deletion of HNRNPF in renal tubules downregulates SGLT2 expression and attenuates hyperfiltration and kidney injury in a diabetic mouse model. HNRNPF/H RNA-binding proteins have been reviewed more broadly in the context of disease.
Berberrubine's Pharmacological Profile
Berberrubine (搜索) is described as an attractive derivative of berberine with multiple pharmacological activities. Berberine itself has been extensively studied in kidney disease: a systematic review and meta-analysis examined its protective effect in diabetic nephropathy, and reviews have summarized its renoprotective effects across various kidney diseases, its anti-diabetic nephropathy potential, and its involvement of ER stress pathways. Berberine exerts renoprotective effects by regulating the AGEs-RAGE signaling pathway in mesangial cells during diabetic nephropathy, and has been shown to attenuate palmitic acid-induced lipotoxicity in human HK-2 cells by promoting PPAR-α.
Berberrubine (搜索) has previously been reported to attenuate potassium oxonate- and hypoxanthine-induced hyperuricemia by regulating urate transporters and the JAK2/STAT3 signaling pathway, and to inhibit thrombosis by regulating the vitamin K catalytic cycle in mice. Alkaloid uptake pathways in renal tubular epithelial cells have been characterized for processed products of Phellodendri chinensis cortex, and organic anion transporting polypeptides have been reviewed for their pharmacology, toxicology, structure and transport mechanisms — relevant to how such alkaloids reach tubular cells.
Therapeutic Implications
The study positions the HNRNPF (搜索)/NR4A1 (搜索)/ER stress axis as a tractable node through which berberrubine (搜索) mitigates PCS-induced tubular injury. Because tubular injury is a key driver of tubulointerstitial fibrosis — the proximal tubule has been proposed as a focus of tubulointerstitial fibrosis — interventions that interrupt uremic toxin-mediated ER stress could have implications beyond acute tubular damage. Iron chelation with deferoxamine has been shown to prevent renal interstitial fibrosis in mice with unilateral ureteral obstruction, illustrating that targeted molecular interventions can modify fibrotic outcomes in preclinical models.
The findings add to a growing body of work on natural compounds and their derivatives in kidney disease, including berberine's modulation of the TLR4 signaling pathway and the phosphatidylinositol 3-kinase/AKT pathway. Further studies will be needed to determine whether the HNRNPF (搜索)/NR4A1 (搜索)/ER stress axis can be engaged therapeutically in patients with CKD, and to define the pharmacokinetic behavior of berberrubine (搜索), whose physicochemical properties and plasma levels after administration to human subjects have been examined for berberine and its metabolites.