Green A R, Begley C G
Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Victoria, Australia.
Int J Cell Cloning. 1992 Sep;10(5):269-76. doi: 10.1002/stem.5530100504.
The helix-loop-helix (HLH) proteins are a family of transcription factors that include proteins critical to differentiation and development in species ranging from plants to mammals. Five members of this family (MYC, SCL, TAL-2, LYL-1 and E2A) are implicated in oncogenic events in human lymphoid tumors because of their consistent involvement in chromosomal translocations. Although activated in T cell leukemias, expression of SCL and LYL-1 is low or undetectable in normal T cell populations. SCL is expressed in erythroid, megakaryocyte and mast cell populations (the same cell lineages as GATA-1, a zinc-finger transcription factor). In addition, both SCL and GATA-1 undergo coordinate modulation during chemically induced erythroid differentiation of mouse erythroleukemia cells and are down-modulated during myeloid differentiation of human K562 cells, thus implying a role for SCL in erythroid differentiation events. However, in contrast to GATA-1, SCL is expressed in the developing brain. Studies of the function of SCL suggest it is also important in proliferation and self-renewal events in erythroid cells.
螺旋-环-螺旋（HLH）蛋白是一类转录因子家族，其中包括对从植物到哺乳动物等多种物种的分化和发育至关重要的蛋白质。该家族的五个成员（MYC、SCL、TAL-2、LYL-1和E2A）由于始终参与染色体易位，因而与人类淋巴肿瘤的致癌事件有关。虽然SCL和LYL-1在T细胞白血病中被激活，但其在正常T细胞群体中的表达很低或无法检测到。SCL在红系、巨核细胞和肥大细胞群体中表达（与锌指转录因子GATA-1相同的细胞谱系）。此外，在化学诱导的小鼠红白血病细胞红系分化过程中，SCL和GATA-1都经历协同调节，而在人K562细胞的髓系分化过程中二者均被下调，因此表明SCL在红系分化事件中发挥作用。然而，与GATA-1不同，SCL在发育中的大脑中表达。对SCL功能的研究表明，它在红系细胞的增殖和自我更新事件中也很重要。
