title: Growth promoting effect of thioredoxin on intestinal epithelial cells.
abstract: Paneth cells are located at the bases of intestinal crypts, and their cytoplasmic granules contain large amounts of zinc. We previously showed that administration of diphenylthiocarbazone (dithizone), a zinc chelater, to rats induced the selective death of Paneth cells. This was followed by a transient wave of epithelial cell proliferation in the entire crypts. In the study described here, we again applied this experimental model in an attempt to identify novel growth-promoting factors in the small intestine. Male Wistar rats were injected with dithizone and killed 6 hr later. Messenger RNAs (mRNAs) were extracted from the terminal ileum for the construction of a cDNA library. This library was then transfected into the human intestinal cell line Caco-2, and the cells that continued to grow in the medium containing only 1% FBS were cloned. One of the cDNA sequences identified from those transfection experiments was the full-length rat thioredoxin (TRX) gene. To confirm the growth-promoting effect of this cDNA, we transfected it into Caco-2 cells again. These clones proliferated in the medium containing only 1% FBS, while the control clones failed to show any growth. Transient oxidative stress exerted by the addition of oxidative reagents diamide and hydrogen peroxide partially suppressed the growth of TRX-transfected cells. Northern hybridization analysis revealed that TRX expression in rat ileum after dithizone treatment was altered in accordance with intestinal epithelial regeneration in the crypts. Single-cell RT-PCR also showed TRX mRNA expression in Paneth cells. These studies identify rat thioredoxin as a growth-promoting factor for intestinal epithelial cells.
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine, Kyoto University, Graduate School of Medicine, 54 Shogoin-Kawara-cho, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Takaishi
authors.forename: Mitsutaka
authors.initials: M
authors.lastname: Sawada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Seno
authors.forename: Takahisa
authors.initials: T
authors.lastname: Kayahara
authors.forename: Yukari
authors.initials: Y
authors.lastname: Morita-Fujisawa
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Fukuzawa
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Chiba
mesh_terms: D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D018938:Caco-2 Cells / Q000187:drug effects / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects*; D003470:Culture Media; D018076:DNA, Complementary / Q000032:analysis; D004195:Disease Models, Animal; D004230:Dithizone; D006801:Humans; D007082:Ileum / Q000166:cytology / Q000187:drug effects; D008297:Male; D008969:Molecular Sequence Data; D019879:Paneth Cells / Q000187:drug effects*; D012333:RNA, Messenger / Q000032:analysis; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D013879:Thioredoxins / Q000494:pharmacology*
chemical_list: D003470:Culture Media; D018076:DNA, Complementary; D012333:RNA, Messenger; D013879:Thioredoxins; D004230:Dithizone