The Rothmund-Thomson syndrome helicase RECQL4 is essential for hematopoiesis
Monique F. Smeets, Elisabetta DeLuca, Meaghan Wall, Julie M. Quach, Alistair M. Chalk, Andrew J. Deans, Jörg Heierhorst, Louise E. Purton, David J. Izon, Carl R. Walkley
Monique F. Smeets, Elisabetta DeLuca, Meaghan Wall, Julie M. Quach, Alistair M. Chalk, Andrew J. Deans, Jörg Heierhorst, Louise E. Purton, David J. Izon, Carl R. Walkley
View: Text | PDF
Research Article Hematology

The Rothmund-Thomson syndrome helicase RECQL4 is essential for hematopoiesis

Abstract

Mutations within the gene encoding the DNA helicase RECQL4 underlie the autosomal recessive cancer-predisposition disorder Rothmund-Thomson syndrome, though it is unclear how these mutations lead to disease. Here, we demonstrated that somatic deletion of Recql4 causes a rapid bone marrow failure in mice that involves cells from across the myeloid, lymphoid, and, most profoundly, erythroid lineages. Apoptosis was markedly elevated in multipotent progenitors lacking RECQL4 compared with WT cells. While the stem cell compartment was relatively spared in RECQL4-deficent mice, HSCs from these animals were not transplantable and even selected against. The requirement for RECQL4 was intrinsic in hematopoietic cells, and loss of RECQL4 in these cells was associated with increased replicative DNA damage and failed cell-cycle progression. Concurrent deletion of p53, which rescues loss of function in animals lacking the related helicase BLM, did not rescue BM phenotypes in RECQL4-deficient animals. In contrast, hematopoietic defects in cells from Recql4Δ/Δ mice were fully rescued by a RECQL4 variant without RecQ helicase activity, demonstrating that RECQL4 maintains hematopoiesis independently of helicase activity. Together, our data indicate that RECQL4 participates in DNA replication rather than genome stability and identify RECQL4 as a regulator of hematopoiesis with a nonredundant role compared with other RecQ helicases.

Authors

Monique F. Smeets, Elisabetta DeLuca, Meaghan Wall, Julie M. Quach, Alistair M. Chalk, Andrew J. Deans, Jörg Heierhorst, Louise E. Purton, David J. Izon, Carl R. Walkley

×

Figure 6

Profound selection against Recql4 deletion in HSCs.

Options: View larger image (or click on image) Download as PowerPoint
Profound selection against Recql4 deletion in HSCs. (A) Fetal liver or w...
(A) Fetal liver or whole BM was isolated from donors of the indicated genotypes and transplanted into irradiated CD45.1 recipients. Hematopoiesis was allowed to establish for 5 weeks; then chimerism was assessed (4-week time point). Recipients were then placed on tamoxifen food for 30 days. PB was serially monitored at the indicated times, and total chimerism (CD45.2+ve) and myeloid chimerism (Mac-1+ve) are shown from each independent experiment. At end point, CD45.2 cells were isolated from the BM and genomic PCR performed to determine RECQL4 status;data shown are representative genotyping results from 1 of the experiments; n = 5 recipients/genotype/experiment. (B) hScl-CreERT R26eYFP Recql4 mice of the indicated genotypes were fed tamoxifen diet for 30 days. One cohort was left for long-term observation (upper panels). At end point, eYFP+ve cells were isolated from the BM and genomic PCR performed to assess Recql4 status; the percentage of eYFP was assessed in the PB and BM. A second cohort was analyzed at the end of the 30-day feeding of tamoxifen. Femur cellularity, contribution of eYFP+ve cells to each phenotypic population, and genomic PCR were performed. n > 3 per genotype per experiment. Data expressed as mean ± SEM, Student’s t test. *P < 0.05.