Telomerase RNA level limits telomere maintenance in X-linked dyskeratosis congenita.

Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA.
Genes & Development (Impact Factor: 12.64). 11/2006; 20(20):2848-58. DOI: 10.1101/gad.1476206
Source: PubMed

ABSTRACT Dyskeratosis congenita (DC) patients suffer a progressive and ultimately fatal loss of hematopoietic renewal correlating with critically short telomeres. The predominant X-linked form of DC results from substitutions in dyskerin, a protein required both for ribosomal RNA (rRNA) pseudouridine modification and for cellular accumulation of telomerase RNA (TER). Accordingly, alternative models have posited that the exhaustion of cellular renewal in X-linked DC arises as a primary consequence of ribosome deficiency or telomerase deficiency. Here we test, for the first time, whether X-linked DC patient cells are compromised for telomerase function at telomeres. We show that telomerase activation in family-matched control cells allows telomere elongation and telomere length maintenance, while telomerase activation in X-linked DC patient cells fails to prevent telomere erosion with proliferation. Furthermore, we demonstrate by phenotypic rescue that telomere defects in X-linked DC patient cells arise solely from reduced accumulation of TER. We also show that X-linked DC patient cells averted from premature senescence support normal levels of rRNA pseudouridine modification and normal kinetics of rRNA precursor processing, in contrast with phenotypes reported for a proposed mouse model of the human disease. These findings support the significance of telomerase deficiency in the pathology of X-linked DC.

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