Expression of mouse telomerase catalytic subunit in embryos and adult tissues

Abstract

Telomerase is a ribonucleoprotein complex that elongates telomeres, allowing the stable maintenance of chromosomes during multiple cell divisions. Here, we describe the isolation and characterization of the catalytic subunit of mouse telomerase, mTERT (mouse telomerase reverse transcriptase), an essential protein component of the telomerase complex. During embryonic development, mTERT mRNA is abundantly expressed in the whole embryo, especially in regions of intense proliferation. We found that the mTERT mRNA expression in both embryonic and adult tissues is independent of the essential RNA component of telomerase, mTR, and therefore, of the formation of active telomerase complexes. mTERT protein is present exclusively in tissues with telomerase activity, such as testis, spleen, and thymus. mTERT protein is barely detectable in the thymus of mTR ؊/؊ mice, suggesting that mTERT protein stability in this tissue may depend on the actual assembly of active telomerase complexes. Finally, we found that mouse and human telomerase catalytic subunit is located in the cell nucleus, and its localization is not regulated during cell cycle progression.

Fibroblast growth factor 2 up regulates telomerase activity in neural precursor cells

“…Expression of the catalytic subunit of telomerase has been shown to be tightly linked to the regulation of the enzymatic activity (Greenberg et al, 1998;Martin-Rivera et al, 1998). As previously described, we found mTERT mRNA in mouse brain tissues regardless the presence or the absence of detectable telomerase activity ( Figure 5a).…”

“…Pluripotent neural cells undergo steps of proliferation, fate commitment and di erentiation. Our study showed that telomerase activity is highly expressed during embryonic cortical neurogenesis and early step of gliogenesis and progressively decreases thereafter during cortex maturation to be undetectable in the normal adult brain (Blasco et al, 1995;Greenberg et al, 1998;Martin-Rivera et al, 1998;Prowse and Greider, 1995). A similar kinetic exists during the postnatal development of the cerebellum, suggesting that telomerase expression and regulation are directly related to the proliferation and di erentiation of neural precursors.…”

“…This is particularly the case of the developing brain. Total brain of murine embryo has been shown to express signi®cant level of telomerase activity (Greenberg et al, 1998;Martin-Rivera et al, 1998;Prowse and Greider, 1995) but precise time schedule, tissular and cellular regulation and the nature of the telomerase expressing cells are still unknown. mTER has been shown to be down-regulated in mouse brain at day 16 after birth (Blasco et al, 1995).…”

Increased hepatic telomerase activity in a rat model of iron overload: A role for altered thiol redox state?

“…Most differentiated human somatic cells lack both telomerase activity and TERT expression, while germ cells, some stem cells and a majority of cancers demonstrate both telomerase activity and TERT expression. In contrast, many tissues of adult rodents, including the liver, show persistent telomerase activity and TERT expression [23][24][25][26]. Consistent with these data, we observed a low level of telomerase activity and TERT expression in control rat livers.…”

“…Relatively little attention has been paid to the effects of disease models on telomeres in rodents, perhaps because of the known differences in telomere length and telomerase activity among human and rodent species [18,[23][24][25][26]. Notwithstanding the species differences, data implying a pathogenic role of telomere shortening in several forms of human pathology suggest that assessment of the effects of disease models on rodent telomeres may provide important insights into the relationship between telomeres and disease processes.…”