The functional heterogeneity of hematopoietic stem cells(HSCs) has been comprehensively investigated by single-cell transplantation assay.However,the heterogeneity regarding their physiological contribution remains an...The functional heterogeneity of hematopoietic stem cells(HSCs) has been comprehensively investigated by single-cell transplantation assay.However,the heterogeneity regarding their physiological contribution remains an open question,especially for those with life-long hematopoietic fate of rigorous selfrenewing and balanced differentiation capacities.In this study,we revealed that Procr expression was detected principally in phenotypical vascular endothelium co-expressing DII4 and CD44 in the midgestation mouse embryos,and could enrich all the HSCs of the embryonic day 11.5(E11.5) aortagonad-mesonephros(AGM) region.We then used a temporally restricted genetic tracing strategy to irreversibly label the Procr-exp res sing cells at E9.5.Interestingly,most labeled mature HSCs in multiple sites(such as AGM) around E11.5 were functionally categorized as lymphomyeloid-balanced HSCs assessed by direct transplantation.Furthermore,the labeled cells contributed to an average of 7.8% of immunophenotypically defined HSCs in E14.5 fetal liver(FL) and 6.9% of leukocytes in peripheral blood(PB) during one-year follow-up.Surprisingly,in aged mice of 24 months,the embryonically tagged cells displayed constant contribution to leukocytes with no bias to myeloid or lymphoid lineages.Altogether,we demonstrated,for the first time,the existence of a subtype of physiologically long-lived balanced HSCs as hypothesized,whose precise embryonic origin and molecular identity await further characterization.展开更多
MADM （Mosaic Analysis with Double Markers） technology offers a genetic approach in mice to visualize and concomitantly manipulate genetically defined cells at clonal level and single cell resolution. MADM employs Cr...MADM （Mosaic Analysis with Double Markers） technology offers a genetic approach in mice to visualize and concomitantly manipulate genetically defined cells at clonal level and single cell resolution. MADM employs Cre recombinase/loxP-dependent interchromosomal mitotic recombination to reconstitute two split marker genes--green GFP and red tdTomato -- and can label sparse clones of homozygous mutant cells in one color and wild-type cells in the other color in an otherwise unlabeled background. At present, major MADM applications include lineage tracing, single cell labeling, conditional knockouts in small populations of cells and induction of uniparental chromosome disomy to assess effects of genomic imprinting. MADM can be applied universally in the mouse with the sole limitation being the specificity of the promoter controlling Cre recombinase expression. Here I review recent developments and extensions of the MADM technique and give an overview of the major discoveries and progresses enabled by the implementation of the novel genetic MADM tools.展开更多
基金supported by grants from the National Key R&D Program of China (2017YFA0103401 and 2016YFA0100601)the National Natural Science Foundation of China(31425012,31930054,31871173 and 81890991)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams (2017ZT07S347)
文摘The functional heterogeneity of hematopoietic stem cells(HSCs) has been comprehensively investigated by single-cell transplantation assay.However,the heterogeneity regarding their physiological contribution remains an open question,especially for those with life-long hematopoietic fate of rigorous selfrenewing and balanced differentiation capacities.In this study,we revealed that Procr expression was detected principally in phenotypical vascular endothelium co-expressing DII4 and CD44 in the midgestation mouse embryos,and could enrich all the HSCs of the embryonic day 11.5(E11.5) aortagonad-mesonephros(AGM) region.We then used a temporally restricted genetic tracing strategy to irreversibly label the Procr-exp res sing cells at E9.5.Interestingly,most labeled mature HSCs in multiple sites(such as AGM) around E11.5 were functionally categorized as lymphomyeloid-balanced HSCs assessed by direct transplantation.Furthermore,the labeled cells contributed to an average of 7.8% of immunophenotypically defined HSCs in E14.5 fetal liver(FL) and 6.9% of leukocytes in peripheral blood(PB) during one-year follow-up.Surprisingly,in aged mice of 24 months,the embryonically tagged cells displayed constant contribution to leukocytes with no bias to myeloid or lymphoid lineages.Altogether,we demonstrated,for the first time,the existence of a subtype of physiologically long-lived balanced HSCs as hypothesized,whose precise embryonic origin and molecular identity await further characterization.
文摘MADM （Mosaic Analysis with Double Markers） technology offers a genetic approach in mice to visualize and concomitantly manipulate genetically defined cells at clonal level and single cell resolution. MADM employs Cre recombinase/loxP-dependent interchromosomal mitotic recombination to reconstitute two split marker genes--green GFP and red tdTomato -- and can label sparse clones of homozygous mutant cells in one color and wild-type cells in the other color in an otherwise unlabeled background. At present, major MADM applications include lineage tracing, single cell labeling, conditional knockouts in small populations of cells and induction of uniparental chromosome disomy to assess effects of genomic imprinting. MADM can be applied universally in the mouse with the sole limitation being the specificity of the promoter controlling Cre recombinase expression. Here I review recent developments and extensions of the MADM technique and give an overview of the major discoveries and progresses enabled by the implementation of the novel genetic MADM tools.
