TRPV4 enhances the cellular uptake of aminoglycoside antibiotics

Abstract

The cochlea and kidney are susceptible to aminoglycoside-induced toxicity. The non-selective cation channel TRPV4 is expressed in kidney distal tubule cells, and hair cells and the stria vascularis in the inner ear. To determine whether TRPV4 is involved in aminoglycoside trafficking, we generated a murine proximal-tubule cell line (KPT2) and a distal-tubule cell line (KDT3). TRPV4 expression was confirmed in KDT3 cells but not in KPT2 cells. Removal of extracellular Ca2+ significantly enhanced gentamicin–Texas-Red (GTTR) uptake by KDT3, indicative of permeation through non-selective cation channels. To determine whether TRPV4 is permeable to GTTR, stable cell lines were generated that express TRPV4 in KPT2 (KPT2-TRPV4). KPT2-TRPV4 cells took up more GTTR than control cell lines (KPT2-pBabe) in the absence of extracellular Ca2+. TRPV4-dependent GTTR uptake was abolished by a point mutation within the crucial pore region of the channel, suggesting that GTTR permeates the TRPV4 channel. In an endolymph-like extracellular environment, clearance of GTTR was attenuated from KPT2-TRPV4 cells in a TRPV4-dependent fashion. We propose that TRPV4 has a role in aminoglycoside uptake and retention in the cochlea.

Fluorescent aminoglycosides reveal intracellular trafficking routes in mechanosensory hair cells

“…A number of alternative entry mechanisms have been proposed in addition to the MET channel or through endocytosis. It has been suggested that AGs enter through other channels including transient receptor potential channels (75)(76)(77). The sodium glucose transporter SLC5A2 may also play a role in AG transport in the kidney (78).…”

Endotoxemia-mediated inflammation potentiates aminoglycoside-induced ototoxicity

“…This could occur via several mechanisms characterized in other cell systems. Aminoglycosides and GTTR can permeate through non-selective cation channels, including the MET channel expressed by hair cells (11, 12), and TRPV4 channels expressed by endothelial cells (70, 71). The sodium-glucose transporter-2 (SGLT2) traffics aminoglycosides into cells, and facilitates aminoglycoside-induced cytotoxicity (72).…”

Comparative analysis of combination kanamycin-furosemide versus kanamycin alone in the mouse cochlea

“…Since then, research efforts to improve our understanding of ototoxicity have been performed primarily in birds, guinea pigs, and in organ culture of neonatal mice (Brummett, 1981; Cheng et al, 2005; Cunningham et al, 2002; Dai et al, 2006; Forge and Li, 2000; Gratacap et al, 1985; Hirose et al, 1997; Jiang et al, 2005; Karasawa et al, 2008; Richardson and Russell, 1991; Rizzi and Hirose, 2007; Wang et al, 2003). Recently, scientists have turned to in vivo experiments in mice to study molecular mechanisms of hair cell susceptibility to ototoxicity.…”