Higher Expression Levels of Aquaporin Family of Proteins in the Kidneys of Arid-Desert Living Lepus yarkandensis

Abstract

Lepus yarkandensis specifically lives in arid climate with rare precipitation of Tarim Basin in western China. Aquaporins (AQPs) are a family of channel proteins that facilitate water transportation across cell membranes. Kidney AQPs play vital roles in renal tubule water permeability and maintenance of body water homeostasis. This study aimed to investigate whether kidney AQPs exhibit higher expression in arid-desert living animals. Immunohistochemistry results revealed localization of AQP1 to the capillary endothelial cells in glomerulus and epithelial cells in proximal tubule and descending thin limbs, AQP2 to the apical plasma membrane of principal cells in the cortical collecting duct (CCD), outer medullary collecting duct (OMCD), and IMCD cells in the initial inner medullary collecting duct (IMCD1) and middle IMCD (IMCD2), and AQP3 and AQP4 to the basolateral plasma membrane of principal cells and IMCD cells in CCD, OMCD, IMCD1, and IMCD2 in L. yarkandensis kidneys. Quantitative real-time PCR analysis showed higher mRNA levels of AQP1, AQP2, AQP3, and AQP4 in L. yarkandensis kidneys compared with Oryctolagus cuniculus. Similar results were obtained by western blotting. Our results suggested that higher expression levels of AQP1, AQP2, AQP3, and AQP4 in L. yarkandensis kidneys favored for drawing more water from the tubular fluid.

Distribution of aquaporins and sodium transporters in the gastrointestinal tract of a desert hare, Lepus yarkandensis

“…And the expression of digestive features that approximately match digestive capacities with dietary loads 59,60 . Furthermore, we also found higher levels of AQP1 and AQP3 in the kidneys of L. yarkandensis 61 . This may be related to the strategy of the L. yarkandensis to conserve body water.…”

“…One week after feeding, we collected the faeces of these animals to measure their water content; the animals were anaesthetized with 3% pentobarbital sodium (0.9 ml/kg). The stomach, duodenum, jejunum, ileum, caecum, colon and rectum (the length of each segment was approximately 0.5 cm) were removed and placed in ice-cold 0.85% sodium chloride solution to remove the contents and were then inflated with 4% paraformaldehyde (Sigma-Aldrich, Shanghai, China) and fixed overnight for HE staining and immunohistochemical examination 61 . And some tissues were stored in RNA preservation solutions for analysis of RNA levels.…”

“…Immunocytochemical studies were performed in Paraffin-embedded gastrointestinal tissue, previously fixed in 4% paraformaldehyde. The experimental steps of immunohistochemistry have been described elsewhere 61 . The primary antibodies used were as follows: anti-AQP1, anti-AQP3, and anti-AQP4 (diluted to 4.0 μg/ml; Proteintech) and anti-ENaC and anti-Na + -K + -ATPase (diluted to 3.0 μg/ml; Proteintech).…”

“…The primary antibodies used were as follows: anti-AQP1, anti-AQP3, and anti-AQP4 (diluted to 4.0 μg/ml; Proteintech) and anti-ENaC and anti-Na + -K + -ATPase (diluted to 3.0 μg/ml; Proteintech). The acquired images were analysed in IpWin32 software 61 .…”

“…Reverse-transcribed cDNA products were amplified by polymerase chain reaction (PCR) with primers specific for AQP1, AQP3, AQP4, ENaC, Na + -K + -ATPase and β-actin (Table 1). The steps for quantitative RT-PCR were described elsewhere 61 .…”