Differential induction responses of δ‐aminolevulinate synthase mRNAs during erythroid differentiation: Use of nonradioactive in situ hybridization

Expression of mRNAs encoding the erythroid‐specific δ‐aminolevulinate synthase (ALAS‐E) and the nonspecific δ‐aminolevulinate synthase (ALAS‐N) were examined in murine Friend virus‐transformed erythroleukemia (MEL) cells using nonradioactive in situ hybridization. Following dimethyl sulfoxide (DMSO) treatment, ALAS‐E mRNA increased markedly, while ALAS‐N mRNA did not increase in wild‐type MEL cells. In contrast, in a DMSO‐resistant clone of MEL cells, ALAS‐E was not detectable before and after DMSO treatment. These findings suggest that ALAS‐E and ALAS‐N mRNAs are under separate controls and that the expression of ALAS‐E mRNA is a critical event in erythroid differentiation.