title: Thyroid transcription factor-1 exhibits osmosensitive transcription in brain-derived cell lines.
abstract: Thyroid transcription factor-1 (TTF-1) belongs to the Nkx family of homeodomain-containing proteins and regulates expression of several important genes in the brain. Our previous studies showed that TTF-1 plays an important role in water homeostasis in the subfornical organ of rats and is involved in cerebrospinal fluid formation by regulation of aquaporin-1 transcription in the choroid plexus. In this study, we examined changes in TTF-1 transcription in response to hypertonicity using promoter assays. TTF-1 was synthesized in several osmosensitive regions of the rat brain. TTF-1 promoter activity was diminished by treatment with hypertonic solutions in a time- and dose-dependent manner in brain-derived cell lines. Additionally, TTF-1 was involved in the regulation of angiotensinogen (Aogen) transcription under a hyperosmotic condition through specific binding domains in the Aogen promoter. These results suggest a possible role of TTF-1 in brain fluid homeostasis in response to changes in the osmotic environment.
authors.affiliation: Department of Biological Sciences, College of Natural Sciences, University of Ulsan, San29, Mugeodong, Namgu, Ulsan 680-749, Republic of Korea.
authors.forename: Jae Geun
authors.initials: JG
authors.lastname: Kim
authors.forename: Kyung Duk
authors.initials: KD
authors.lastname: Bae
authors.forename: Chang Ho
authors.initials: CH
authors.lastname: Yun
authors.forename: Hye Li
authors.initials: HL
authors.lastname: Im
authors.forename: Jeong Woo
authors.initials: JW
authors.lastname: Park
authors.forename: Il Seong
authors.initials: IS
authors.lastname: Nam-Goong
authors.forename: Young Il
authors.initials: YI
authors.lastname: Kim
authors.forename: Byung Ju
authors.initials: BJ
authors.lastname: Lee
mesh_terms: D000808:Angiotensinogen / Q000235:genetics*; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002460:Cell Line; D005786:Gene Expression Regulation / Q000187:drug effects; D008297:Male; D009687:Nuclear Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D009995:Osmosis; D009997:Osmotic Pressure; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012965:Sodium Chloride / Q000494:pharmacology; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
chemical_list: C000614416:Nkx2-1 protein, rat; D009687:Nuclear Proteins; D012333:RNA, Messenger; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D000808:Angiotensinogen; D012965:Sodium Chloride