Expression of MAK-V/Hunk in renal distal tubules and its possible involvement in proliferative suppression.
MAK-V/Hunk is an SNF1-related serine/threonine kinase which was previously shown to be highly expressed in the mammary gland and central nervous system. In this study, we found MAK-V/Hunk is abundantly and specifically expressed in the thick ascending limbs and distal convoluted tubules (DCT) of the kidney from the embryonic stage to the adult stage. We demonstrated that dietary salt depletion significantly enhances renal MAK-V/Hunk mRNA levels compared with a normal-salt diet. To analyze the possible renal cellular function of this kinase, we employed mouse distal convoluted tubule (mDCT) cells. The results of reverse transcriptase-polymerase chain reaction and Western blot analysis revealed that MAK-V/Hunk is expressed endogenously in mDCT cells. Overexpression of MAK-V/Hunk by adenoviral gene transfer significantly inhibited the ANG II-induced stimulation of c-fos gene transcription and suppressed the ANG II-mediated increases in transforming growth factor-beta production into the medium. This phenomenon was accompanied by inhibition of ANG II-induced activation of BrdU incorporation. On the other hand, the MAK-V/Hunk knockdown by siRNA activated the ANG II-induced c-fos gene expression. In the consecutive sections stained for MAK-V/Hunk and AT(1) receptor, MAK-V/Hunk-immunopositive distal tubules expressed the AT(1) receptor. This is the first report on the intrarenal localization of MAK-V/Hunk and its cellular function in renal tubular cells.
Sakai
Masashi
M
Department of Medical Science and Cardiorenal Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
Tamura
Kouichi
K
Tsurumi
Yuko
Y
Tanaka
Yutaka
Y
Koide
Yuichi
Y
Matsuda
Miyuki
M
Ishigami
Tomoaki
T
Yabana
Machiko
M
Tokita
Yasuo
Y
Hiroi
Yukio
Y
Komuro
Issei
I
Umemura
Satoshi
S
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D049109:Cell Proliferation; D004039:Diet, Sodium-Restricted; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D007150:Immunohistochemistry; D007668:Kidney / Q000196:embryology / Q000378:metabolism; D007686:Kidney Tubules, Distal / Q000166:cytology* / Q000201:enzymology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D014018:Tissue Distribution
D048868:Adaptor Proteins, Signal Transducing; C119712:Agtrap protein, mouse; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D011994:Recombinant Proteins; D011494:Protein Kinases; C417729:Hunk protein, mouse; D017346:Protein Serine-Threonine Kinases