Increased NHE2 expression in rat intestinal epithelium during ontogeny is transcriptionally mediated

• Published in: American Journal of Physiology: Cell Physiology Vol. 275; no. 4; pp. C1143 - C1150
• Main Authors: Collins, James F, Kiela, Pawel R, Xu, Hua, Zeng, Jiamin, Ghishan, Fayez K
• Format: Journal Article
• Language: English
• Published: United States 01.10.1998
• Subjects: Aging; Animals; Gene Expression Regulation, Developmental; Hydrogen-Ion Concentration; Intestinal Mucosa - growth & development; Intestinal Mucosa - metabolism; Jejunum - growth & development; Jejunum - metabolism; Male; Rats; Rats, Sprague-Dawley; RNA, Messenger - biosynthesis; Sodium-Hydrogen Exchangers - biosynthesis; Sodium-Hydrogen Exchangers - genetics; Transcription, Genetic
• ISSN: 0363-6143; 0002-9513; 1522-1563
• DOI: 10.1152/ajpcell.1998.275.4.c1143

Departments of Pediatrics and Physiology, Steele Memorial Children's Research Center, University of Arizona Health Sciences Center, Tucson, Arizona 85724 We have previously described changes in intestinal brush-border membrane vesicle (BBMV) Na + /H + exchange activity and characterized Na + /H + exchanger (NHE3) expression during rat ontogeny. The current studies were designed to investigate developmental changes in NHE2 expression in rat intestine. In previous studies, pH-dependent uptake of Na + in jejunal BBMV utilizing HOE-694 inhibition demonstrated that NHE2 functional protein levels were lowest in 2-wk-old rats, higher in 3-wk-old and adult rats, and highest in 6-wk-old rats [Collins et al. Am. J. Physiol . 273 ( Cell Physiol. 42): C1937-C1946, 1997]. In the current investigation, Northern blot analyses showed that NHE2 mRNA levels in the jejunum were similar in 6-wk-old, adult, and 3-wk-old rats and three- to fivefold lower in 2-wk-old rats. In situ hybridization of 2- and 6-wk-old rat intestine with NHE2-specific probes confirmed Northern blot observations. Polyclonal antibodies were developed against an NHE2-specific peptide from amino acids 652-661. Western blots with NHE2 antiserum showed that the intensity of a specific 90-kDa band was lowest in 2-wk-old animals and four- to sixfold higher in 3- and 6-wk-old and adult animals. Immunohistochemical analysis showed specific staining of NHE2 antiserum to only the apical intestinal membrane. Furthermore, nuclear run-on analyses showed a 1.7-fold higher NHE2 transcription rate in 6-wk-old rats than in 2-wk-old rats. Overall, the current data suggest that increases in NHE2 expression upon weaning are mediated by increased gene transcription. rat intestinal development; sodium/hydrogen exchanger; brush-border membrane; transcription rate analysis; jejunum