Essential roles for Pot1b in HSC self-renewal and survival

Y Wang, MF Shen, S Chang - Blood, The Journal of the …, 2011 - ashpublications.org
Y Wang, MF Shen, S Chang
Blood, The Journal of the American Society of Hematology, 2011ashpublications.org
Maintenance of mammalian telomeres requires both the enzyme telomerase and shelterin,
which protect telomeres from inappropriately activating DNA damage response checkpoints.
Dyskeratosis congenita is an inherited BM failure syndrome disorder because of defects in
telomere maintenance. We have previously shown that deletion of the shelterin component
Pot1b in the setting of telomerase haploinsufficiency results in rapid telomere shortening
and fatal BM failure in mice, eliciting phenotypes that strongly resemble human syskeratosis …
Abstract
Maintenance of mammalian telomeres requires both the enzyme telomerase and shelterin, which protect telomeres from inappropriately activating DNA damage response checkpoints. Dyskeratosis congenita is an inherited BM failure syndrome disorder because of defects in telomere maintenance. We have previously shown that deletion of the shelterin component Pot1b in the setting of telomerase haploinsufficiency results in rapid telomere shortening and fatal BM failure in mice, eliciting phenotypes that strongly resemble human syskeratosis congenita. However, it was unclear why BM failure occurred in the setting of Pot1b deletion. In this study, we show that Pot1b plays an essential role in HSC survival. Deletion of Pot1b results in increased apoptosis, leading to severe depletion of the HSC reserve. BM from Pot1bΔ/Δ mice cannot compete with BM from wild-type mice to provide multilineage reconstitution, indicating that there is an intrinsic requirement for Pot1b the maintenance of HSC function in vivo. Elimination of the p53-dependent apoptotic function increased HSC survival and significantly extended the lifespan of Pot1b-null mice deficient in telomerase function. Our results document for the first time the essential role of a component of the shelterin complex in the maintenance of HSC and progenitor cell survival.
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