title: Prothymosin alpha mRNA levels are invariant throughout the cell cycle.
abstract: Prothymosin alpha (PT-alpha) mRNA levels were evaluated at different stages during the cell cycle. NIH 3T3 cells were synchronized: (a) by serum deprivation, (b) by mitotic shake off after nocodazole arrest, and (c) by double thymidine block. Cell synchronism was estimated by flow cytometry. In cells grown in serum-free medium, PT-alpha mRNA levels were almost undetectable. 14 h after serum restoration PT-alpha mRNA was induced as had been described by others (Eschendfeldt, W. H., and Berger, S. L. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 9403-9407). PT-alpha mRNA induction seems to require the synthesis of proteic factor(s) since PT-alpha mRNA response to serum restoration was abolished in the presence of cycloheximide. Interestingly, cycling cells that were synchronized at different stages of the cycle by means of mitotic shake off after nocodazole arrest or double thymidine block did not show variations in the levels of PT-alpha mRNA when progressed synchronously through the cycle. On the contrary, histone H4 mRNA was expressed only during the S phase. These data indicate that PT-alpha mRNA was present in roughly the same amount through all phases of the cell cycle, arguing against the concept that PT-alpha is a cell cycle-regulated gene.
authors.affiliation: Departamento de Fisiologia, Laboratorio de Neurociencias Ramon Dominguez, Facultad de Medicina, Santiago de Compostela, Spain.
authors.forename: J B
authors.initials: JB
authors.lastname: Zalvide
authors.forename: E
authors.initials: E
authors.lastname: Cancio
authors.forename: C V
authors.initials: CV
authors.lastname: Alvarez
authors.forename: B J
authors.initials: BJ
authors.lastname: Regueiro
authors.forename: F
authors.initials: F
authors.lastname: Dominguez
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001769:Blood; D002453:Cell Cycle; D002455:Cell Division; D016895:Culture Media, Serum-Free; D003513:Cycloheximide / Q000494:pharmacology; D005434:Flow Cytometry; D015870:Gene Expression; D051379:Mice; D015739:Nocodazole / Q000494:pharmacology; D011498:Protein Precursors / Q000235:genetics*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism*; D013936:Thymidine / Q000037:antagonists & inhibitors; D013947:Thymosin / Q000031:analogs & derivatives* / Q000235:genetics
chemical_list: D016895:Culture Media, Serum-Free; D011498:Protein Precursors; D012333:RNA, Messenger; C040782:prothymosin alpha; D013947:Thymosin; D003513:Cycloheximide; D015739:Nocodazole; D013936:Thymidine