Expression of Telomerase Reverse Transcriptase Subunit (TERT) and Telomere Sizing in Pig Ovarian Follicles
Valentina Russo 1*, Paolo Berardinelli 1, Alessandra Martelli 1, Oriana Di Giacinto 1, Delia Nardinocchi 1, Donatella Fantasia 1 and Barbara Barboni 1
1 Dipartimento di Scienze Biomediche Comparate, Università degli Studi di Teramo, Teramo, Italy (VR,PB,AM,OD,DN,BB), and Dipartimento di Scienze Biomediche, Sezione di Genetica Medica, Università di Chieti, Chieti, Italy (DF)
* To whom correspondence should be addressed. E-mail: vrusso{at}unite.it.
Submitted on December 20, 2004
Accepted on 19 November 2005
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Abstract |
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Telomerase is crucial for chromosome stability since it maintains telomere length. Little is known about telomerase in the ovarian follicles, where an intense cell division is crucial to sustain oestrus cycle and to drive oocyte development. The present research was performed to detect, by immunohistochemistry, the distribution of telomerase catalytic subunit (TERT) during folliculogenesis and to study the effect of TERT expression on telomeres. To this aim, telomere length has been measured on FISH processed sections either in follicular or in germ cells. In primary and preantral follicles, TERT was observed in granulosa and in germ cells, with a typical nuclear location. During antral differentiation, only somatic cells close to the antrum (antral layer) and cumulus cells maintained TERT expression. The relative oocytes located TERT in the ooplasm independently from the process of meiotic maturation. FISH results indicate that exists a correlation between TERT expression and telomere size. In fact, progressively bigger telomeres were observed from preantral to antral follicles where longer structures were recorded in cells of the cumulus oophorus and of the antral layer than those of the basal one. Stable and elongated telomeres were detected in fully grown oocytes that lost the functional TERT distribution within the nucleus.
Key Words:
immunohistochemistry, fluorescence in situ hybridization, pig, TERT, telomeres, ovarian follicle, granulosa cells, oocyte