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Intrinsic and extrinsic control of hemopoietic stem cell numbers: mapping of a stem cell gene.

de Haan G, Van Zant G - J. Exp. Med. (1997)

Bottom Line: The resulting strain distribution pattern showed high concordance with a marker that mapped to chromosome 18 (19 cM).Linkage with this genomic interval was associated with a likelihood of odds score of 3.3, surpassing the level required for significance.Interestingly, this segment, containing the EGR-1 gene, shows synteny with human chromosome 5q, a region strongly associated with various hematological malignancies.

View Article: PubMed Central - PubMed

Affiliation: Blood and Marrow Transplant Program, Division of Hematology/Oncology, University of Kentucky Medical Center, Lexington, Kentucky 40536-0093, USA.

ABSTRACT
We evaluated in vivo interactions between extrinsic (growth factor induced) and intrinsic (genetically determined) effectors of mouse primitive hemopoietic stem cell proliferation and numbers. Accordingly, stem cell frequency and cell cycle kinetics were assessed in eight strains of inbred mice using the cobblestone area-forming cell (CAFC) assay. A strong inverse correlation was observed between mouse lifespan and the number of autonomously cycling progenitors (CAFC day 7) in the femur. The population size of primitive stem cells (CAFC day 35) varied widely (up to sevenfold) among strains, unlike total CAFC day 7 numbers (cycling and quiescent), which were similar. Administration of the early acting cytokine flt-3 ligand to these strains resulted in activation of quiescent primitive stem cells exclusively in strains with high endogenous stem cell numbers (DBA and AKR), but was unrelated to strain-specific progenitor cell cycling. To map loci affecting stem cell frequency, we quantified stem cells in BXD recombinant inbred mice (offspring of C57BL/6 and DBA/2). The resulting strain distribution pattern showed high concordance with a marker that mapped to chromosome 18 (19 cM). Linkage with this genomic interval was associated with a likelihood of odds score of 3.3, surpassing the level required for significance. Interestingly, this segment, containing the EGR-1 gene, shows synteny with human chromosome 5q, a region strongly associated with various hematological malignancies. Our findings indicate that a gene mapping to this region is mutated in either C57BL/6 or DBA/2 (and possibly AKR) mice. These studies in apparently healthy mice may facilitate the identification of a gene implicated in human 5q-syndromes.

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Individual mouse lifespan is negative correlated with the  number of cycling CAFC day 7 per femur. The fraction of cells in S-phase  was determined by using an in vitro HU suicide technique. The linear regression equation was: CAFC day 7 cycling = 13159 − 18.47 × lifespan,  r2 = 0.66, P <0.0145.
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Figure 2: Individual mouse lifespan is negative correlated with the number of cycling CAFC day 7 per femur. The fraction of cells in S-phase was determined by using an in vitro HU suicide technique. The linear regression equation was: CAFC day 7 cycling = 13159 − 18.47 × lifespan, r2 = 0.66, P <0.0145.

Mentions: We have recently used the in vitro CAFC assay (Fig. 1) in combination with an HU suicide technique to evaluate the number of stem cells in active cell cycle (2). CAFC day 7, a population of cells which has been shown to consist primarily of multipotent progenitors (18–20), showed a substantial HU kill, whereas primitive CAFC day 35, which contain cells with long-term repopulating ability (18, 20), were not killed by a 1-h incubation with HU, demonstrating their proliferative quiescence (2, 20). The eight strains of mice which were used in this study were first evaluated for the pool size of cycling CAFC day 7 per femur during steady state hemopoiesis (Fig. 2). For five of these strains (CBA, C3H/He, DBA/2, BALB/c, and C57BL/6) we have previously shown that the percentage of progenitor cells in the S-phase of the cell cycle is inversely related to maximal mouse lifespan (2). The inclusion of three new strains (AKR, A, and 129/Sv) in this study confirmed and extended our initial observation. AKR mice have the shortest lifespan of all inbred mouse strains, and invariably develop leukemia before they have reached 1 yr of age (21). Our data show that AKR mice have one of the largest cycling CAFC day 7 pools of all strains tested, ∼8,000 CAFC day 7 per femur. In contrast, 129/Sv mice have a long lifespan, approximately as long as that of C57BL/6 mice, and we were unable to detect any S-phase CAFC day 7 in this strain. Strain A mice have a lifespan which is intermediate between those of 129/Sv and AKR mice, and correspondingly the pool of cycling progenitors per femur in these mice was ∼4,000, in between the values obtained for 129/Sv and AKR mice. Although these data do not imply any causative relationship between lifespan and hemopoietic progenitor cell cycling, we hypothesize that other continuously renewing tissues may show a similar strain distribution pattern (SDP). If that is the case, it is appealing to argue that lifespan is influenced by systemic cell proliferation, which would affect cumulative DNA damage potentially caused by errors during DNA duplication, reactive oxygen radicals, telomere erosion, etc. It is noteworthy that caloric restriction, which has long been known to increase lifespan, is accompanied by a reduced mitotic index of multiple cell systems (22).


Intrinsic and extrinsic control of hemopoietic stem cell numbers: mapping of a stem cell gene.

de Haan G, Van Zant G - J. Exp. Med. (1997)

Individual mouse lifespan is negative correlated with the  number of cycling CAFC day 7 per femur. The fraction of cells in S-phase  was determined by using an in vitro HU suicide technique. The linear regression equation was: CAFC day 7 cycling = 13159 − 18.47 × lifespan,  r2 = 0.66, P <0.0145.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199035&req=5

Figure 2: Individual mouse lifespan is negative correlated with the number of cycling CAFC day 7 per femur. The fraction of cells in S-phase was determined by using an in vitro HU suicide technique. The linear regression equation was: CAFC day 7 cycling = 13159 − 18.47 × lifespan, r2 = 0.66, P <0.0145.
Mentions: We have recently used the in vitro CAFC assay (Fig. 1) in combination with an HU suicide technique to evaluate the number of stem cells in active cell cycle (2). CAFC day 7, a population of cells which has been shown to consist primarily of multipotent progenitors (18–20), showed a substantial HU kill, whereas primitive CAFC day 35, which contain cells with long-term repopulating ability (18, 20), were not killed by a 1-h incubation with HU, demonstrating their proliferative quiescence (2, 20). The eight strains of mice which were used in this study were first evaluated for the pool size of cycling CAFC day 7 per femur during steady state hemopoiesis (Fig. 2). For five of these strains (CBA, C3H/He, DBA/2, BALB/c, and C57BL/6) we have previously shown that the percentage of progenitor cells in the S-phase of the cell cycle is inversely related to maximal mouse lifespan (2). The inclusion of three new strains (AKR, A, and 129/Sv) in this study confirmed and extended our initial observation. AKR mice have the shortest lifespan of all inbred mouse strains, and invariably develop leukemia before they have reached 1 yr of age (21). Our data show that AKR mice have one of the largest cycling CAFC day 7 pools of all strains tested, ∼8,000 CAFC day 7 per femur. In contrast, 129/Sv mice have a long lifespan, approximately as long as that of C57BL/6 mice, and we were unable to detect any S-phase CAFC day 7 in this strain. Strain A mice have a lifespan which is intermediate between those of 129/Sv and AKR mice, and correspondingly the pool of cycling progenitors per femur in these mice was ∼4,000, in between the values obtained for 129/Sv and AKR mice. Although these data do not imply any causative relationship between lifespan and hemopoietic progenitor cell cycling, we hypothesize that other continuously renewing tissues may show a similar strain distribution pattern (SDP). If that is the case, it is appealing to argue that lifespan is influenced by systemic cell proliferation, which would affect cumulative DNA damage potentially caused by errors during DNA duplication, reactive oxygen radicals, telomere erosion, etc. It is noteworthy that caloric restriction, which has long been known to increase lifespan, is accompanied by a reduced mitotic index of multiple cell systems (22).

Bottom Line: The resulting strain distribution pattern showed high concordance with a marker that mapped to chromosome 18 (19 cM).Linkage with this genomic interval was associated with a likelihood of odds score of 3.3, surpassing the level required for significance.Interestingly, this segment, containing the EGR-1 gene, shows synteny with human chromosome 5q, a region strongly associated with various hematological malignancies.

View Article: PubMed Central - PubMed

Affiliation: Blood and Marrow Transplant Program, Division of Hematology/Oncology, University of Kentucky Medical Center, Lexington, Kentucky 40536-0093, USA.

ABSTRACT
We evaluated in vivo interactions between extrinsic (growth factor induced) and intrinsic (genetically determined) effectors of mouse primitive hemopoietic stem cell proliferation and numbers. Accordingly, stem cell frequency and cell cycle kinetics were assessed in eight strains of inbred mice using the cobblestone area-forming cell (CAFC) assay. A strong inverse correlation was observed between mouse lifespan and the number of autonomously cycling progenitors (CAFC day 7) in the femur. The population size of primitive stem cells (CAFC day 35) varied widely (up to sevenfold) among strains, unlike total CAFC day 7 numbers (cycling and quiescent), which were similar. Administration of the early acting cytokine flt-3 ligand to these strains resulted in activation of quiescent primitive stem cells exclusively in strains with high endogenous stem cell numbers (DBA and AKR), but was unrelated to strain-specific progenitor cell cycling. To map loci affecting stem cell frequency, we quantified stem cells in BXD recombinant inbred mice (offspring of C57BL/6 and DBA/2). The resulting strain distribution pattern showed high concordance with a marker that mapped to chromosome 18 (19 cM). Linkage with this genomic interval was associated with a likelihood of odds score of 3.3, surpassing the level required for significance. Interestingly, this segment, containing the EGR-1 gene, shows synteny with human chromosome 5q, a region strongly associated with various hematological malignancies. Our findings indicate that a gene mapping to this region is mutated in either C57BL/6 or DBA/2 (and possibly AKR) mice. These studies in apparently healthy mice may facilitate the identification of a gene implicated in human 5q-syndromes.

Show MeSH
Related in: MedlinePlus