EX VIVO EVIDENCE FOR THE WATER CHANNEL AND CELL-TO-CELL ADHESION FUNCTIONS OF C-TERMINALLY END-CLEAVED AQUAPORIN 0

Abstract

Purpose : Investigate whether C-terminally end-cleaved aquaporin 0 (AQP0) functions as a water channel and a cell-to-cell adhesion (CTCA) protein in the lens fiber cells.

Methods : A genetically engineered KI mouse model (AQP0-KI) expressing C-terminally end cleaved AQP0 that has 1-246 amino acids, instead of the full length 263 amino acids, was developed. Lens fiber cell membrane vesicles (FCMVs) were prepared from wild type (WT), AQP0-KI, AQP0 heterozygous (AQP0-Htz) and AQP0 knockout (AQP0-KO) mice, and water permeability (P_f) was measured. Adhesion assay was performed using adhesion-deficient L-cell and FCMVs from the above mentioned genotypes.

Results : FCMVs of AQP0-Htz showed reduced P_f and CTCA compared to those of WT, whereas AQP0-KO FCMVs showed lack of P_f and CTCA. FCMVs of AQP0-KI exhibited no significant alteration in P_f compared to those of WT. However, CTCA of AQP0-KI FCMVs was significantly higher than that of WT FCMVs.

Conclusions : C-terminally end-cleaved AQP0 functions both as a water channel and a CTCA protein in the lens fiber cell membranes. End truncation plays an important role in increasing CTCA between the fiber cells.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.