title: Polyamines are necessary for normal expression of the transforming growth factor-beta gene during cell migration.
abstract: The current study tests the hypothesis that intracellular polyamines are involved in the regulation of gene expression of transforming growth factor-beta (TGF-beta) during epithelial cell migration after wounding. Administration of alpha-difluoromethylornithine (DFMO), a specific inhibitor of ornithine decarboxylase (the first rate-limiting enzyme for polyamine synthesis), depleted cellular polyamines putrescine, spermidine, and spermine in IEC-6 cells. DFMO also significantly reduced basal levels of TGF-beta mRNA in unwounded cells. Gene expression of TGF-beta was dramatically stimulated after wounding of a monolayer of cells not treated with DFMO. TGF-beta mRNA levels significantly increased from 4 to 12 h after wounding, peaking at 6 h at a level eight times the prewounding control. Increased levels of TGF-beta mRNA in IEC-6 cells after wounding were paralleled by an increase in TGF-beta content. Depletion of intracellular polyamines in DFMO-treated cells significantly inhibited increased expression of the TGF-beta gene in response to wounding. Cell migration also significantly decreased in DFMO-treated cells. In the presence of DFMO, exogenous TGF-beta restored cell migration to normal. These results indicate that 1) polyamine depletion induced by DFMO is associated with decreases in the expression of the TGF-beta gene and cell migration in IEC-6 cells and 2) exogenous TGF-beta reverses the inhibitory effect of polyamine depletion on cell migration. These findings suggest that polyamines are required for epithelial cell migration in association with their ability to regulate TGF-beta gene expression.
authors.affiliation: Department of Surgery, University of Maryland Medical School and Baltimore Veterans Affairs Medical Center, 21201, USA.
authors.forename: J Y
authors.initials: JY
authors.lastname: Wang
authors.forename: M J
authors.initials: MJ
authors.lastname: Viar
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: H J
authors.initials: HJ
authors.lastname: Shi
authors.forename: S A
authors.initials: SA
authors.lastname: McCormack
authors.forename: L R
authors.initials: LR
authors.lastname: Johnson
mesh_terms: D000818:Animals; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D000518:Eflornithine / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression; D006706:Homeostasis; D007421:Intestine, Small / Q000166:cytology / Q000293:injuries / Q000502:physiology*; D007425:Intracellular Membranes / Q000378:metabolism; D065108:Ornithine Decarboxylase Inhibitors; D011073:Polyamines / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D012016:Reference Values; D016212:Transforming Growth Factor beta / Q000235:genetics* / Q000494:pharmacology; D014947:Wounds and Injuries / Q000235:genetics
chemical_list: D004791:Enzyme Inhibitors; D065108:Ornithine Decarboxylase Inhibitors; D011073:Polyamines; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D000518:Eflornithine