Tadjali Mehrdad, Zhou Sheng, Rehg Jerold, Sorrentino Brian P
Division of Experimental Hematology, Department of Hematology/Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
Stem Cells. 2006 Jun;24(6):1556-63. doi: 10.1634/stemcells.2005-0562. Epub 2006 Feb 16.
Stem cells from a variety of tissues can be identified by a side population (SP) phenotype based on Hoechst 33342 dye efflux. The Abcg2 transporter is expressed in hematopoietic stem cells (HSCs) and confers this dye efflux activity. To further explore the relationship among Abcg2 expression, the SP phenotype, and HSC activity, we have generated mice in which a green fluorescent protein (GFP) reporter gene was inserted into the Abcg2 locus. In these mice, the majority of bone marrow (BM) cells that expressed the Abcg2/ GFP allele were Ter119(+) erythroid cells. The Abcg2/GFP allele was also expressed in approximately 10% of lineage-negative (Lin(-)) and in 91% of SP cells using stringent conditions for the SP assay. Flow cytometric sorting was used to isolate various Abcg2/GFP(+) BM cell populations that were then tested for HSC activity in transplant assays. There was significant enrichment for HSCs in sorted Lin(-)/ GFP(+) cells, with a calculated HSC frequency of approximately one in 75. There was no HSC activity detected in Lin(-)/GFP(+) cells. Altogether, these results show that Abcg2 is expressed on essentially all murine BM HSCs and can be used as a prospective marker for HSC enrichment.
基于Hoechst 33342染料外排的侧群（SP）表型可识别来自多种组织的干细胞。Abcg2转运蛋白在造血干细胞（HSC）中表达，并赋予这种染料外排活性。为了进一步探究Abcg2表达、SP表型和HSC活性之间的关系，我们构建了将绿色荧光蛋白（GFP）报告基因插入Abcg2基因座的小鼠。在这些小鼠中，表达Abcg2/GFP等位基因的大多数骨髓（BM）细胞是Ter119(+)红系细胞。使用严格的SP检测条件时，Abcg2/GFP等位基因在约10%的谱系阴性（Lin(-)）细胞和91%的SP细胞中也有表达。通过流式细胞术分选分离出各种Abcg2/GFP(+) BM细胞群体，然后在移植试验中检测其HSC活性。在分选的Lin(-)/GFP(+)细胞中HSC有显著富集，计算得出的HSC频率约为75个中有1个。在Lin(-)/GFP(+)细胞中未检测到HSC活性。总之，这些结果表明Abcg2在基本上所有的小鼠BM HSC上均有表达，可作为富集HSC的一种前瞻性标志物。
