Telomerase activity in plant cells

Abstract

Telomerase is a ribonucleoprotein enzyme which elongates the G-rich strand of telomeric DNA to compensate for the progressive reduction in its length due to incomplete replication of chromosome ends, which in human somatic cells leads to cell cycle arrest upon shortening of telomeres to a critical length. To examine the possible involvement of telomerase in metabolism of plant genetic material, we used cells of Nicotiana tabacum strain TBY-2, a stable long-term culture which has kept a constant pattern of restriction fragments from chromosome termini during its 6 month period of cultivation in our laboratory. In a direct assay for telomerase, a 5' end-labeled plant telomeric oligonueleotide S'(TTTAGGG)6 3' was elongated in a TBY-2 cell extract, showing a pausing pattern which is a characteristic feature of telomerases from other organisms. The elongation was inhibited by RNase A pretreatment of the extract. We conclude that plant cells possess telomerase which is used for maintenance of their telomeres.

Developmental Control of Telomere Lengths and Telomerase Activity in Plants

“…The presence of telomerase activity in such differentiated cells supports our data on the stable maintenance of telomere lengths in plants. Telomerase also was detected in suspension cultures of tobacco (Fajkus et al, 1996;Heller et al, 1996), carrot, soybean, Arabidopsis, and rice (Fitzgerald et al, 1996). These results as well as our data on the telomerase activity in M. album calli indicate that telomerase (re)activation is essential for plant cell proliferation.…”

“…Telomerase activity has been detected in plants by using a direct method (Fajkus et al, 1996) or a polymerase chain reaction (PCR)-based telomerase repeat amplification protocol (TRAP) assay (Fitzgerald et al, 1996;Heller et al, 1996). Telomerase seems to be developmentally regulated in plants, which is similar to the way it is regulated in humans.…”

Perturbation of NgTRF1 Expression Induces Apoptosis-Like Cell Death in Tobacco BY-2 Cells and Implicates NgTRF1 in the Control of Telomere Length and Stability

“…DNA on the gel was then blotted and hybridized with a telomere repeat probe (TTTAGGG) 70 (Figure 4). In our experimental conditions, samples from wild-type cells migrated as a typical telomeric smear, with fragments ranging from ;65 to 15 kb (Fajkus et al, 1995(Fajkus et al, , 1996. On the other hand, all of the 35S::NgTRF1 cell lines analyzed showed significantly shortened telomeres, whose lengths ranged between 45 and 10 kb, depending on the line ( Figure 4A).…”

Developmentally Regulated Telomerase Activity Is Correlated with Chromosomal Healing during Chromatin Diminution in Ascaris suum

“…Telomerase is a ribonucleoprotein complex: it contains a reverse transcriptase catalytic subunit and associated protein subunits, as well as an intrinsic RNA molecule in which a short sequence serves as the template for the synthesis of the G-rich strand of telomeric DNA (reviewed in reference 53). Widespread among eukaryotes, telomerase activity has been identified in ciliates (23, 64, 76), yeast (11, 36, 37), Plasmodium falciparum (8), mammals (45, 60), amphibians (38), sponges (32), and higher plants (16,18,28). In single-cell eukaryotes, telomerase is constitutively active, and the maintenance of the telomere length is essential for the proliferative growth of the vegetative cells (for a review, see reference 22).…”