International Journal of Cell Cloning, Vol 10, 269-276, Copyright © 1992 by AlphaMed Press
SCL and related hemopoietic helix-loop-helix transcription factors
AR Green and CG Begley
Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Victoria, Australia.
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.
