Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
Mass Spectrometry Research Center, Vanderbilt University, Nashville, Tennessee, United States.
Invest Ophthalmol Vis Sci. 2020 Sep 1;61(11):36. doi: 10.1167/iovs.61.11.36.
The lens uses circulating fluxes of ions and water that enter the lens at both poles and exit at the equator to maintain its optical properties. We have mapped the subcellular distribution of the lens aquaporins (AQP0, AQP1, and AQP5) in these water influx and efflux zones and investigated how their membrane location is affected by changes in tension applied to the lens by the zonules.
Immunohistochemistry using AQP antibodies was performed on axial sections obtained from rat lenses that had been removed from the eye and then fixed or were fixed in situ to maintain zonular tension. Zonular tension was pharmacologically modulated by applying either tropicamide (increased) or pilocarpine (decreased). AQP labeling was visualized using confocal microscopy.
Modulation of zonular tension had no effect on AQP1 or AQP0 labeling in either the water efflux or influx zones. In contrast, AQP5 labeling changed from membranous to cytoplasmic in response to both mechanical and pharmacologically induced reductions in zonular tension in both the efflux zone and anterior (but not posterior) influx zone associated with the lens sutures.
Altering zonular tension dynamically regulates the membrane trafficking of AQP5 in the efflux and anterior influx zones to potentially change the magnitude of circulating water fluxes in the lens.
晶状体通过两极处进入和赤道处流出的离子和水流循环来维持其光学特性。我们已经绘制了这些水流入和流出区域的晶状体水通道蛋白（AQP0、AQP1 和 AQP5）的亚细胞分布，并研究了它们的膜定位如何受到悬韧带对晶状体施加的张力变化的影响。
使用 AQP 抗体对从眼球中取出并固定或原位固定以保持悬韧带张力的大鼠晶状体的轴向切片进行免疫组织化学染色。通过应用托品酰胺（增加）或毛果芸香碱（减少）来药理学调节悬韧带张力。使用共聚焦显微镜观察 AQP 标记。
悬韧带张力的调节对水流出或流入区的 AQP1 或 AQP0 标记没有影响。相比之下，AQP5 标记在机械和药理学诱导的悬韧带张力降低时，从前部（但不是后部）流入区和与晶状体缝线相关的流出区从膜状变为细胞质状。
动态改变悬韧带张力调节了流出和前部流入区 AQP5 的膜运输，从而可能改变晶状体中循环水通量的大小。
