Int J Biol Sci 2016; 12(6):730-745. doi:10.7150/ijbs.15066 This issue

Research Paper

Different Modulatory Mechanisms of Renal FXYD12 for Na+-K+-ATPase between Two Closely Related Medakas upon Salinity Challenge

Wen-Kai Yang1, Chao-Kai Kang2, An-Di Hsu1, Chia-Hao Lin3, Tsung-Han Lee1,4✉

1. Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan.
2. Tainan Hydraulics Laboratory, National Cheng Kung University, Tainan 709, Taiwan.
3. National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.
4. Department of Biological Science and Technology, China Medical University, Taichung 404, Taiwan.

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Yang WK, Kang CK, Hsu AD, Lin CH, Lee TH. Different Modulatory Mechanisms of Renal FXYD12 for Na+-K+-ATPase between Two Closely Related Medakas upon Salinity Challenge. Int J Biol Sci 2016; 12(6):730-745. doi:10.7150/ijbs.15066. Available from

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Graphic abstract

Upon salinity challenge, the Na+-K+-ATPase (NKA) of fish kidney plays a crucial role in maintaining ion and water balance. Moreover, the FXYD protein family was found to be a regulator of NKA. Our preliminary results revealed that fxyd12 was highly expressed in the kidneys of the two closely related euryhaline medaka species (Oryzias dancena and O. latipes) from different natural habitats (brackish water and fresh water). In this study, we investigated the expression and association of renal FXYD12 and NKA α-subunit as well as potential functions of FXYD12 in the two medakas. These findings illustrated and compared the regulatory roles of FXYD12 for NKA in kidneys of the two medakas in response to salinity changes. In this study, at the mRNA and/or protein level, the expression patterns were similar for renal FXYD12 and NKA in the two medakas. However, different patterns of NKA activities and different interaction levels between FXYD12 and NKA were found in the kidneys of these two medakas. The results revealed that different strategies were used in the kidneys of the two medaka species upon salinity challenge. On the other hand, gene knockdown experiments demonstrated that the function of O. dancena FXYD12 allowed maintenance of a high level of NKA activity. The results of the present study indicated that the kidneys of the examined euryhaline medakas originating from brackish water and fresh water exhibited different modulatory mechanisms through which renal FXYD12 enhanced NKA activity to maintain internal homeostasis. Our findings broadened the knowledge of expression and functions of FXYD proteins, the modulators of NKA, in vertebrates.

Keywords: FXYD12, Kidney, Na+-K+-ATPase, Oryzias, Salinity.