Prestin is the motor protein of cochlear outer hair cells （OHCs）. It is able to perform rapid and reciprocal electromechanical conversion that underlies OHC electromotility. Due to the inadequate size of a single pr...Prestin is the motor protein of cochlear outer hair cells （OHCs）. It is able to perform rapid and reciprocal electromechanical conversion that underlies OHC electromotility. Due to the inadequate size of a single prestin molecule to form the2 nm intramembraneous protein particles （IMPs） in the OHC lateral membrane （LM）, the possibility of prestin oligomerization has been proposed. It has been suggested that prestin molecules form highorder oligomers, most likely as the tetramer, in heterologous systems. In OHCs, however, the oligomeric structure of prestin remains unclear. Here we calculated the prestin-related charge density in both gerbil and guinea pig OHCs through measuring their nonlinear capacitance （NLC） and LM surface area, showing that the average charge density （22, 608 μm-2 in gerbils; 19, 460 μm-2 in guinea pigs） is statistically 4 times the average density of IMPs （5,686 μm-2 in gerbils; 5, 000 μm-2 in guinea pigs）. This suggests that each IMP contains four prestin molecules based upon the notion that each prestin transfers a single elementary charge, implying that prestin forms tetramers in OHCs. To determine whether the prestin tetramer functions as a mechanical unit, we subsequently compared the slope factors （α） of electromotility and NLC simultaneously measured from the same OHC, showing that the α values of the two are statistically the same. This suggests that each prestin molecule in the tetramer is mechanically independent and equally contributes to OHC electromotility.展开更多
目的探讨噪声性听力损伤(NIHL)对耳蜗Prestin蛋白表达的影响。方法无特定病原体级健康雄性豚鼠60只随机分为对照组和85、95、105、115 dB声压级(SPL)暴露组5组,除对照组外,其余4组分别予以85、95、105、115 dB SPL的高斯白噪声暴露,每天...目的探讨噪声性听力损伤(NIHL)对耳蜗Prestin蛋白表达的影响。方法无特定病原体级健康雄性豚鼠60只随机分为对照组和85、95、105、115 dB声压级(SPL)暴露组5组,除对照组外,其余4组分别予以85、95、105、115 dB SPL的高斯白噪声暴露,每天6 h,连续28 d,暴露前1 d和暴露结束后第7天分别进行听性脑干反应测量,噪声暴露结束后第7天,分别进行耳蜗病理学检查、逆转录-聚合酶链反应分析Prestin mRNA表达水平、蛋白免疫印迹法分析Prestin蛋白表达水平。结果对照组和85、95、105、115 dB SPL暴露组的永久性听阈位移(PTS)水平依次为(2.08±0.97)、(7.08±2.79)、(13.33±1.63)、(21.88±1.88)和(27.92±2.34)dB nHL,上述5组PTS水平两两比较,差异均有统计学意义(P<0.05)。病理学检查结果显示115 dB SPL暴露组豚鼠耳蜗出现明显毛细胞损伤。上述5组Prestin mRNA的2-ΔΔCt值依次为(1.12±0.39)、(0.98±0.24)、(1.53±0.55)、(2.84±0.51)和(7.65±0.63);105 dB SPL暴露组Prestin mRNA的2-ΔΔCt值分别高于对照组及85、95 dB SPL暴露组(P<0.05),115 dB SPL暴露组Prestin mRNA的2-ΔΔCt值分别高于其余4组(P<0.05)。上述5组Prestin蛋白相对灰度值依次为(0.18±0.07)、(0.20±0.09)、(0.29±0.10)、(0.45±0.19)和(1.19±0.16);105 dB SPL暴露组Prestin蛋白相对灰度值分别高于对照组及85、95 dB SPL暴露组(P<0.05),115 dB SPL暴露组Prestin蛋白相对灰度值分别高于其余4组(P<0.05)。结论严重的NIHL会导致耳蜗外毛细胞Prestin的表达代偿性增高。展开更多
基金supported by an NIDCD grant (R01DC004696) to DHby National Natural Science Foundation of China grants 30871398, 30730040 and 30628030 to SY and DHsupported bygrant number G20RR024001 from the National Center for Research Resources
文摘Prestin is the motor protein of cochlear outer hair cells （OHCs）. It is able to perform rapid and reciprocal electromechanical conversion that underlies OHC electromotility. Due to the inadequate size of a single prestin molecule to form the2 nm intramembraneous protein particles （IMPs） in the OHC lateral membrane （LM）, the possibility of prestin oligomerization has been proposed. It has been suggested that prestin molecules form highorder oligomers, most likely as the tetramer, in heterologous systems. In OHCs, however, the oligomeric structure of prestin remains unclear. Here we calculated the prestin-related charge density in both gerbil and guinea pig OHCs through measuring their nonlinear capacitance （NLC） and LM surface area, showing that the average charge density （22, 608 μm-2 in gerbils; 19, 460 μm-2 in guinea pigs） is statistically 4 times the average density of IMPs （5,686 μm-2 in gerbils; 5, 000 μm-2 in guinea pigs）. This suggests that each IMP contains four prestin molecules based upon the notion that each prestin transfers a single elementary charge, implying that prestin forms tetramers in OHCs. To determine whether the prestin tetramer functions as a mechanical unit, we subsequently compared the slope factors （α） of electromotility and NLC simultaneously measured from the same OHC, showing that the α values of the two are statistically the same. This suggests that each prestin molecule in the tetramer is mechanically independent and equally contributes to OHC electromotility.
文摘目的探讨噪声性听力损伤(NIHL)对耳蜗Prestin蛋白表达的影响。方法无特定病原体级健康雄性豚鼠60只随机分为对照组和85、95、105、115 dB声压级(SPL)暴露组5组,除对照组外,其余4组分别予以85、95、105、115 dB SPL的高斯白噪声暴露,每天6 h,连续28 d,暴露前1 d和暴露结束后第7天分别进行听性脑干反应测量,噪声暴露结束后第7天,分别进行耳蜗病理学检查、逆转录-聚合酶链反应分析Prestin mRNA表达水平、蛋白免疫印迹法分析Prestin蛋白表达水平。结果对照组和85、95、105、115 dB SPL暴露组的永久性听阈位移(PTS)水平依次为(2.08±0.97)、(7.08±2.79)、(13.33±1.63)、(21.88±1.88)和(27.92±2.34)dB nHL,上述5组PTS水平两两比较,差异均有统计学意义(P<0.05)。病理学检查结果显示115 dB SPL暴露组豚鼠耳蜗出现明显毛细胞损伤。上述5组Prestin mRNA的2-ΔΔCt值依次为(1.12±0.39)、(0.98±0.24)、(1.53±0.55)、(2.84±0.51)和(7.65±0.63);105 dB SPL暴露组Prestin mRNA的2-ΔΔCt值分别高于对照组及85、95 dB SPL暴露组(P<0.05),115 dB SPL暴露组Prestin mRNA的2-ΔΔCt值分别高于其余4组(P<0.05)。上述5组Prestin蛋白相对灰度值依次为(0.18±0.07)、(0.20±0.09)、(0.29±0.10)、(0.45±0.19)和(1.19±0.16);105 dB SPL暴露组Prestin蛋白相对灰度值分别高于对照组及85、95 dB SPL暴露组(P<0.05),115 dB SPL暴露组Prestin蛋白相对灰度值分别高于其余4组(P<0.05)。结论严重的NIHL会导致耳蜗外毛细胞Prestin的表达代偿性增高。
