Dissecting the role of dysfunctional telomeres to stem cell biology and immunity
Rationale and Objectives
Dyskeratosis congenita (DC) is a genetic inherited syndrome characterised by short telomeres . Telomerase is a specialised ribonucleoprotein complex composed of Telomerase Reverse Transcriptase (TERT), Telomerase RNA Component (TERC), and dyskerin, which stabilises telomerase complex. More than half of DC patients harbour mutations in telomere maintenance genes and immunodeficiencies and bone marrow failure (BMF) represent their main cause of mortality. Telomere attrition is one of the best-characterised mechanisms of cellular senescence. We hypothesise that telomere shortening triggers a DDR-dependent senescence in DC patients' BM-derived HSPC leading to severe BMF and proinflammatory detrimental programs. DC6 will focus on the autosomal forms of the disease caused by TERC gene mutations, preferentially affecting paediatric patients. To that end, DC-like human HSPC will be generated by the (CRIPSR)-Cas system.
Our engineered DC human model will allow us to study the causes of HSPC premature exhaustion and hematopoietic dysfunctions, with a specific focus on:
1) exacerbated DDR (imaging/flow cytometry).
2) transcriptional and epigenetic changes (scRNAseq/histone marks).
3) proinflammatory phenotype (luminex assay) and will be used as a platform for the development of new therapies for DC patients. Functional experiments will include colony-forming assays in semisolid medium and long-term hematopoietic reconstitution by transplantation. Validation experiments will be performed in BM-derived HSPCs from DC patients obtained through a collaboration with the Gaslini Hospital in Genoa.
We expect to find increased inflammatory programs in HSPCs bearing DC genetic defects, with consequent impaired stem cell functions and lymphoid output. Although we selected a paradigmatic rare genetic disease with immunological defects, we expect that our findings could be exploited for the treatment of all inherited bone marrow failure syndromes, linked to telomeres or DNA repair or inflammatory gene defects, as well as in healthy individuals, who show progressive shortening of telomeres in hematopoietic stem cells with age.
RFHMO (Stepensky/Schejter) to receive training on bone marrow sample processing, m10-m12 (2 months); IJC to utilize epigenetics to identify the molecular determinants of HSPC dysfunctions, m13-15 (2 months); GRL (Vento-Tormo), to identify the impact of the genetic inactivation in cellular and molecular phenotype by sc-omics, m20-22 (2 months). Finally, the DC will do a secondment at OneChain to learn the standards of genetic manipulation in the biotech sector, m30-31 (1 month).
PhD in Biomedicine, Universita Vita-Salute San Raffaele, Milan (Italy)