Maturation of TonEBP expression in developing rat kidney.
Tonicity-responsive enhancer binding protein (TonEBP) is a transcriptional activator of the Rel family. In the renal medulla, TonEBP stimulates genes encoding proteins involved in cellular accumulation of organic osmolytes, the vasopressin-regulated urea transporters (UT-A), and heat shock protein 70. To understand the role of TonEBP in the development of urinary concentrating ability, TonEBP expression during rat kidney development was investigated. In embryonic kidneys, TonEBP immunoreactivity was detected 16 days postcoitus in the cytoplasm of the endothelial cells surrounding the medullary collecting ducts (MCD). By 20 days, TonEBP was detected in most tubular profiles in the medulla, including the loop of Henle and MCD, and interstitial cells. The intensity of TonEBP immunoreactivity was much higher in the vasa recta than the tubules. In addition, immunoreactivity was localized predominantly to the cytoplasm. On postnatal day 1, two major changes were observed. TonEBP immunoreactivity shifted to the nucleus, and the intensity of TonEBP immunoreactivity of the tubules increased dramatically. These changes were associated with an increase in TonEBP and sodium-myo-inositol cotransporter mRNA abundance. Thereafter, TonEBP expression in tubular profiles increased moderately. The adult pattern of TonEBP expression was established at postnatal day 21 coincident with full maturation of the renal medulla. Thus expression of TonEBP in developing kidneys occurred predominantly in the medulla and preceded expression of its target genes, including UT-A. These data suggest that TonEBP contributes to the development of urine-concentrating ability.
Han
Ki-Hwan
KH
Departmrnt of Anatomy and Cell Death Disease Research Center, Catholic University Medical College, Seoul 137-701, South Korea.
Woo
Seung Kyoon
SK
Kim
Wan-Young
WY
Park
Soo-Hyun
SH
Cha
Jung-Ho
JH
Kim
Jin
J
Kwon
H Moo
HM
D000818:Animals; D051398:Aquaporin 1; D020346:Aquaporins / Q000378:metabolism; D018118:Chloride Channels / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007668:Kidney / Q000196:embryology / Q000254:growth & development* / Q000378:metabolism*; D007671:Kidney Concentrating Ability / Q000502:physiology; D007679:Kidney Medulla / Q000187:drug effects / Q000378:metabolism; D023282:Nuclease Protection Assays; D009994:Osmolar Concentration; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D015534:Trans-Activators / Q000096:biosynthesis*; D014157:Transcription Factors
C496022:Aqp1 protein, rat; D020346:Aquaporins; C489932:CLCNKA protein, human; D018118:Chloride Channels; C082118:Clcnka protein, rat; C492199:Nfat5 protein, rat; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; D051398:Aquaporin 1; D000254:Sodium-Potassium-Exchanging ATPase