TRPM4-mediated sodium dysregulation drives acute renal tubular injury

doi:10.3969/j.issn.1674-8115.2026.09.005

Abstract

Abstract:

Objective ·To investigate dynamic changes in the expression of transient receptor potential melastatin 4 (TRPM4) in acute kidney injury (AKI), its associations with renal tubular epithelial cell death and inflammatory responses, and the protective effects of TRPM4 inhibition in vivo or small interfering RNA (siRNA)-mediated Trpm4 knockdown in vitro on renal tubular injury. Methods ·Murine ischemia-reperfusion (IR) and cisplatin-induced AKI models were established, respectively. Tubular injury was evaluated by hematoxylin-eosin (H-E) staining, and renal TRPM4 expression was assessed. In the IR model, mice received the TRPM4 inhibitor glibenclamide. Western blotting was performed to quantify renal injury markers [T cell immunoglobulin and mucin domain-containing protein 1 (TIM-1) and neutrophil gelatinase-associated lipocalin (NGAL)] and inflammasome pathway components [nucleotide-binding domain leucine‑rich repeat and pyrin domain‑containing receptor 3 (NLRP3), cleaved caspase-1 (c-CASP-1), and interleukin-18 (IL-18)]. In vitro, a human proximal tubular epithelial cell line (PTEC) and a mouse renal tubular epithelial cell line (TCMK-1) were subjected to injury stimuli including cisplatin, hydrogen peroxide (H₂O₂), and hypoxia/reoxygenation (H/R), followed by assessment of TRPM4 and injury-associated signaling. Quantitative PCR (qPCR) was used to examine Trpm4 and ninjurin 1 (Ninj1) transcriptional responses across a cisplatin dose gradient. In TCMK-1 cells, Trpm4 was silenced using siRNA; plasma membrane injury and intracellular Na⁺ load were quantified by propidium iodide (PI) staining and the CoroNa-AM probe using flow cytometry. RNA sequencing was conducted in siRNA-Trpm4-treated cells, with Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis performed to characterize transcriptional programs impacted by Trpm4 knockdown. Results ·① Both AKI models exhibited marked tubular injury accompanied by significant upregulation of TRPM4 in renal tubular epithelial cells. ② Glibenclamide treatment significantly reduced serum creatinine (sCr) and blood urea nitrogen (BUN) levels, alleviated IR-induced tubular damage, decreased TIM-1 and NGAL levels, and suppressed activation of the NLRP3-CASP-1-IL-18 axis. ③ In vitro exposure to cisplatin or H/R induced TRPM4 upregulation and enhanced injury-associated signaling, while increasing cisplatin doses further elevated Trpm4 and Ninj1 mRNA levels. ④ Trpm4 knockdown reduced the proportion of PI-positive cells after cisplatin challenge and significantly decreased CoroNa-AM signals [including the proportion of CoroNa-AM^high cells and geometric mean fluorescence intensity (GeoMFI)] within the PI⁻ gate, indicating attenuation of intracellular Na⁺ overload. Conclusion ·TRPM4-mediated sodium dysregulation is a critical driver of renal tubular injury, and intracellular Na⁺ overload is involved in the amplification of NLRP3 inflammasome activation. Targeting TRPM4 may constitute a key brake on the injury-inflammation cycle in AKI.

Key words: acute kidney injury (AKI), transient receptor potential melastatin 4 (TRPM4), renal tubular epithelial cell, glibenclamide

CLC Number:

R692.5

Wang Jialing, Wang Yanzhe, Miao Naijun, Wang Xiaoxia. TRPM4-mediated sodium dysregulation drives acute renal tubular injury[J]. Journal of Shanghai Jiao Tong University (Medical Science), 2026,(9): 1199-1211.

Figures/Tables 4

Fig 1 Cisplatin- and IR-induced AKI is accompanied by aggravated tubular injury, upregulated TRPM4 expression, and increased cell apoptosis

Fig 2 In vitro injury induces TRPM4 upregulation, and Trpm4 knockdown alleviates membrane injury and reduces Na⁺ overload

Fig 3 TRPM4 inhibition attenuates IR-induced renal dysfunction, tubular injury, and inflammation-related signaling in vivo

Fig 4 Trpm4 knockdown reshapes transcriptional programs associated with oxidative stress, inflammation/pyroptosis, and ion transport at the transcriptomic level

TrendMD

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