title: Thymidine kinase 1 expression defines an activated G1 state of the cell cycle as revealed with site-specific antibodies and ArrayScan assays.
abstract: Thymidine kinase 1 (TK1) is a DNA salvage enzyme involved in the synthesis of thymidine triphosphate needed during S phase. Although TK1 has been utilized as a cell proliferation marker for many years no well-characterized antibodies are available. The preparation and properties of two types of poly- and monoclonal anti-TK1 peptide antibodies are described and they are used to determine the levels of TK1 in intact cells. Expression of TK1, c-fos, cyclin B1, Ki67, phosphorylated histone H3, phosphorylated ribosomal protein S6, as well as bromodeoxyuridine (BrdU) incorporation in human normal dermal fibroblast cultures were studied with high-content ArrayScan fluorescence microscopy. The levels of TK1 increased 6-7h after serum re-addition to starved cells as they passed through G1, S and G2/M phases, which was earlier than the increase in Ki67 protein levels and before BrdU incorporation was detected. Thus, a population of activated G1 cells with high TK1 and low Ki67 expression could be identified and their role in cell proliferation can now be clarified.
authors.affiliation: Biology Department, Oncology, Nerviano Medical Sciences, Nerviano, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Gasparri
authors.forename: Naining
authors.initials: N
authors.lastname: Wang
authors.forename: Sven
authors.initials: S
authors.lastname: Skog
authors.forename: Arturo
authors.initials: A
authors.lastname: Galvani
authors.forename: Staffan
authors.initials: S
authors.lastname: Eriksson
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D048708:Cell Growth Processes / Q000502:physiology; D002478:Cells, Cultured; D002645:Chickens; D005260:Female; D016195:G2 Phase / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D010766:Phosphorylation; D013937:Thymidine Kinase / Q000096:biosynthesis* / Q000276:immunology / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D013937:Thymidine Kinase; C092717:thymidine kinase 1