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A protective mechanism against antibiotic-induced ototoxicity: role of prestin.

Yu L, Jiang XH, Zhou Z, Tsang LL, Yu MK, Chung YW, Zhang XH, Wang AM, Tang H, Chan HC - PLoS ONE (2011)

Bottom Line: Hearing loss or ototoxicity is one of the major side effects associated with the use of the antibiotics, particularly aminoglycosides (AGs), which are the most commonly used antibiotics worldwide.In the present study, we test the possibility that prestin, the motor protein specifically expressed in the basolateral membrane of outer hair cells (OHCs) in the cochlea with electromotility responsible for sound amplification, may be involved in the process of AG-induced apoptosis in OHCs.Our results from both mice model and cultured cell line indicate a previously unexpected role of prestin, in mediating antibiotic-induced apoptosis, the effect of which is associated with its anion-transporting capacity.

View Article: PubMed Central - PubMed

Affiliation: Epithelial Cells Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, ShaTin, Hong Kong.

ABSTRACT
Hearing loss or ototoxicity is one of the major side effects associated with the use of the antibiotics, particularly aminoglycosides (AGs), which are the most commonly used antibiotics worldwide. However, the molecular and cellular events involved in the antibiotic-induced ototoxicity remains unclear. In the present study, we test the possibility that prestin, the motor protein specifically expressed in the basolateral membrane of outer hair cells (OHCs) in the cochlea with electromotility responsible for sound amplification, may be involved in the process of AG-induced apoptosis in OHCs. Our results from both mice model and cultured cell line indicate a previously unexpected role of prestin, in mediating antibiotic-induced apoptosis, the effect of which is associated with its anion-transporting capacity. The observed downregulation of prestin mRNA prior to detectable apoptosis in OHCs and hearing loss in the antibiotic-treated mice is interesting, which may serve as a protective mechanism against hearing loss induced by AGs in the early stage.

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Prestin-expressing CHO cells exhibit anion transporting capacity.Control or prestin transfected cells were cultured on cover slides for 24 h, and incubated with Krebs-Henseleit (KH) medium. (A): Measurement of membrane potential by voltage- fluorescent dye DiBAC4(3). Arrows indicate the time when 100 µM kanamycin was added in the KH media. (a), Control cells; (b), prestin-transfected cells; (c), Quantitative analysis of increasing rate of membrane potential; (d), Quantitative analysis of change of membrane potential compared to the base line. (B): Intracellular chloride concentration was measured by MQAE dye in control or prestin transfected cells incubated in KH media. ***, p<0.01. (C): Intracellular chloride concentration was measured in KH media depleted of chloride. NS, no significant difference.
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pone-0017322-g004: Prestin-expressing CHO cells exhibit anion transporting capacity.Control or prestin transfected cells were cultured on cover slides for 24 h, and incubated with Krebs-Henseleit (KH) medium. (A): Measurement of membrane potential by voltage- fluorescent dye DiBAC4(3). Arrows indicate the time when 100 µM kanamycin was added in the KH media. (a), Control cells; (b), prestin-transfected cells; (c), Quantitative analysis of increasing rate of membrane potential; (d), Quantitative analysis of change of membrane potential compared to the base line. (B): Intracellular chloride concentration was measured by MQAE dye in control or prestin transfected cells incubated in KH media. ***, p<0.01. (C): Intracellular chloride concentration was measured in KH media depleted of chloride. NS, no significant difference.

Mentions: Having established that prestin-expressing cells are more susceptible to kanamycin-induced apoptosis, we next sought to investigate possible mechanisms underlying this differential sensitivity to kanamycin. Since prestin is known to have both voltage-sensing and ion transporting capacities [20], [21], it may sense membrane voltage changes induced by kanamycin, a known ionophore allowing influx of cations [22], with conformational changes that facilitate anion transporting capacity of prestin. We first examined whether kanamycin could induce membrane potential changes in prestin-transfected or vector control CHO cells. As shown in Figure 4A, 100 µM kanamycin induced a rapid depolarization of membrane potential as reflected by a sharp rise in the fluorescence intensity of the voltage-sensitive dye (DiBAC4(3)) in both vector control and prestin-expressing CHO cells (Fig. 4Aa,b), indicating cation influx induced by kanamycin as expected. Interestingly, the change in membrane potential in the prestin-expressing CHO cells was less than that of the vector control (Fig. 4Ad). In addition, the initial rate of increase in membrane potential in the prestin-expressing CHO cells also appeared to be slower as compared to that of vector control, although there was no significant difference (Fig. 4Ac). These results suggest possible concurrent influx of anions through prestin or other channels, which counteracts with the part of effect of the kanamycin-induced cation influx on membrane potential.


A protective mechanism against antibiotic-induced ototoxicity: role of prestin.

Yu L, Jiang XH, Zhou Z, Tsang LL, Yu MK, Chung YW, Zhang XH, Wang AM, Tang H, Chan HC - PLoS ONE (2011)

Prestin-expressing CHO cells exhibit anion transporting capacity.Control or prestin transfected cells were cultured on cover slides for 24 h, and incubated with Krebs-Henseleit (KH) medium. (A): Measurement of membrane potential by voltage- fluorescent dye DiBAC4(3). Arrows indicate the time when 100 µM kanamycin was added in the KH media. (a), Control cells; (b), prestin-transfected cells; (c), Quantitative analysis of increasing rate of membrane potential; (d), Quantitative analysis of change of membrane potential compared to the base line. (B): Intracellular chloride concentration was measured by MQAE dye in control or prestin transfected cells incubated in KH media. ***, p<0.01. (C): Intracellular chloride concentration was measured in KH media depleted of chloride. NS, no significant difference.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3045444&req=5

pone-0017322-g004: Prestin-expressing CHO cells exhibit anion transporting capacity.Control or prestin transfected cells were cultured on cover slides for 24 h, and incubated with Krebs-Henseleit (KH) medium. (A): Measurement of membrane potential by voltage- fluorescent dye DiBAC4(3). Arrows indicate the time when 100 µM kanamycin was added in the KH media. (a), Control cells; (b), prestin-transfected cells; (c), Quantitative analysis of increasing rate of membrane potential; (d), Quantitative analysis of change of membrane potential compared to the base line. (B): Intracellular chloride concentration was measured by MQAE dye in control or prestin transfected cells incubated in KH media. ***, p<0.01. (C): Intracellular chloride concentration was measured in KH media depleted of chloride. NS, no significant difference.
Mentions: Having established that prestin-expressing cells are more susceptible to kanamycin-induced apoptosis, we next sought to investigate possible mechanisms underlying this differential sensitivity to kanamycin. Since prestin is known to have both voltage-sensing and ion transporting capacities [20], [21], it may sense membrane voltage changes induced by kanamycin, a known ionophore allowing influx of cations [22], with conformational changes that facilitate anion transporting capacity of prestin. We first examined whether kanamycin could induce membrane potential changes in prestin-transfected or vector control CHO cells. As shown in Figure 4A, 100 µM kanamycin induced a rapid depolarization of membrane potential as reflected by a sharp rise in the fluorescence intensity of the voltage-sensitive dye (DiBAC4(3)) in both vector control and prestin-expressing CHO cells (Fig. 4Aa,b), indicating cation influx induced by kanamycin as expected. Interestingly, the change in membrane potential in the prestin-expressing CHO cells was less than that of the vector control (Fig. 4Ad). In addition, the initial rate of increase in membrane potential in the prestin-expressing CHO cells also appeared to be slower as compared to that of vector control, although there was no significant difference (Fig. 4Ac). These results suggest possible concurrent influx of anions through prestin or other channels, which counteracts with the part of effect of the kanamycin-induced cation influx on membrane potential.

Bottom Line: Hearing loss or ototoxicity is one of the major side effects associated with the use of the antibiotics, particularly aminoglycosides (AGs), which are the most commonly used antibiotics worldwide.In the present study, we test the possibility that prestin, the motor protein specifically expressed in the basolateral membrane of outer hair cells (OHCs) in the cochlea with electromotility responsible for sound amplification, may be involved in the process of AG-induced apoptosis in OHCs.Our results from both mice model and cultured cell line indicate a previously unexpected role of prestin, in mediating antibiotic-induced apoptosis, the effect of which is associated with its anion-transporting capacity.

View Article: PubMed Central - PubMed

Affiliation: Epithelial Cells Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, ShaTin, Hong Kong.

ABSTRACT
Hearing loss or ototoxicity is one of the major side effects associated with the use of the antibiotics, particularly aminoglycosides (AGs), which are the most commonly used antibiotics worldwide. However, the molecular and cellular events involved in the antibiotic-induced ototoxicity remains unclear. In the present study, we test the possibility that prestin, the motor protein specifically expressed in the basolateral membrane of outer hair cells (OHCs) in the cochlea with electromotility responsible for sound amplification, may be involved in the process of AG-induced apoptosis in OHCs. Our results from both mice model and cultured cell line indicate a previously unexpected role of prestin, in mediating antibiotic-induced apoptosis, the effect of which is associated with its anion-transporting capacity. The observed downregulation of prestin mRNA prior to detectable apoptosis in OHCs and hearing loss in the antibiotic-treated mice is interesting, which may serve as a protective mechanism against hearing loss induced by AGs in the early stage.

Show MeSH
Related in: MedlinePlus