Down-regulation of human protein kinase C α is associated with terminal neutrophil differentiation

Abstract

We have established an RNase protection method to quantify the expression of mRNA for the human protein kinase C (PK-C) isoforms α, β1, β2, and γ. This was used to investigate whether each isoform is differentially expressed during the differentiation of hematopoietic cells. Myeloid and lymphoid cells express PK-C α, β1, and β2 mRNAs in various proportions. PK-C γ mRNA was detected in human brain, but not in hematopoietic cells. PK-C α mRNA decreases as HL-60 cells mature to a neutrophil phenotype in response to retinoic acid, but its abundance does not change during monocytic differentiation in response to vitamin D3. PK-C α mRNA and protein were undetectable in peripheral blood neutrophils, but are present in monocytes. The mRNAs for PK-C β1 and β2 isoforms increase during HL-60 differentiation and are expressed in both neutrophils and monocytes. Therefore, the PK-C α isoform is specifically down-regulated during human neutrophil terminal differentiation. These data suggest that mature neutrophil functions do not require the PK-C α isoform. © 1992 by The American Society of Hematology.