TELOMERASE ACTIVATOR1 induces telomerase activity and potentiates responses to auxin in Arabidopsis

• Published in: The Plant cell 2004-11, Vol.16 (11), p.2910-2922
• Main Authors: Ren, S, Johnston, J.S, Shippen, D.E, McKnight, T.D
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence - genetics; Arabidopsis - drug effects; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis Proteins - genetics; Arabidopsis Proteins - isolation & purification; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Auxins; Carrier Proteins - genetics; Carrier Proteins - isolation & purification; Carrier Proteins - metabolism; Cell cycle; Cell Cycle - genetics; cytokinins; DNA; DNA, Complementary - analysis; DNA, Complementary - genetics; Drug Resistance - genetics; Enzyme Activation - drug effects; Enzyme Activation - physiology; Enzyme Activators - isolation & purification; Enzyme Activators - metabolism; enzyme activity; Gene expression regulation; Gene Expression Regulation, Plant - genetics; Genes; indole acetic acid; Indoleacetic Acids - metabolism; Indoleacetic Acids - pharmacology; Leaves; Molecular Sequence Data; Mutants; Mutation - genetics; nucleotide sequences; Phenotype; Plant cells; Plant growth; Plant roots; Plant Roots - enzymology; Plant Roots - growth & development; Plants; regulatory proteins; root growth; Signal Transduction - drug effects; Signal Transduction - physiology; TAC1 gene; telomerase; Telomerase - metabolism; Telomeres; Zinc Fingers - genetics
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.104.025072

Telomerase activity is highly regulated, abundant in rapidly dividing cells and reproductive organs, but undetectable in most other differentiated tissues. Little is known about mechanisms that regulate telomerase. Here, we used a biochemical assay to screen activation-tagged lines of Arabidopsis thaliana for mutants that ectopically express this enzyme in their leaves. In one such mutant, a previously uncharacterized zinc-finger protein we designate TELOMERASE ACTIVATOR1 (TAC1) is overexpressed and induces telomerase in fully differentiated leaves without stimulating progression through the cell cycle. Reducing endogenous concentrations of auxin in the mutant blocks the ability of TAC1 to induce telomerase. This result, along with other phenotypes of the mutant, such as the ability of cells to grow in culture without exogenous auxin and increased sensitivity of primary root growth to exogenous auxin, indicates that TAC1 not only is part of the previously reported link between auxin and telomerase expression but also potentiates other classic responses to this phytohormone.