Down-regulation of P sub(2U)-purinergic nucleotide receptor messenger RNA expression during in vitro differentiation of human myeloid leukocytes by phorbol esters or inflammatory activators

• Published in: Molecular pharmacology Vol. 51; no. 1; pp. 97 - 108
• Main Authors: Martin, KA, Kertesy, S B, Dubyak, G R
• Format: Journal Article
• Language: English
• Published: 01.01.1997
• ISSN: 0026-895X

HL-60 human promyelocytic leukocytes express G protein-coupled P sub(2U)-purinergic nucleotide receptors (P sub(2U)R or P2y sub(2)R) that activate inositol phospholipid hydrolysis and Ca super(2+) mobilization in response to ATP or UTP. We examined the expression of functional P sub(2U)R and P sub(2U)R mRNA levels during in vitro differentiation of HL-60 cells by dibutyryl-cAMP (Bt sub(2)cAMP), which induces a granulocyte/neutrophil phenotype, or by phorbol-12-myristate-13-acetate (PMA), which induces a monocyte /macrophage phenotype. Both P sub(2U)R function and P sub(2U)R mRNA levels were only modestly attenuated during granulocytic differentiation by Bt sub(2)cAMP. In contrast, P sub(2U)R function, as assayed by either Ca super(2+) mobilization or inositol trisphosphate generation, was greatly reduced in PMA-differentiated cells. This inhibition of P sub(2U)R function was strongly correlated with PMA-induced decreases in P sub(2U)R mRNA levels, as assayed by Northern blot analysis or reverse transcription-polymerase chain reactionbased quantification. Although PMA induced an early, transient up-regulation of P sub(2U)R mRNA, this was rapidly followed by a sustained decrease in P sub(2U)R mRNA to a level 5-10-fold lower than that in undifferentiated HL-60 cells. The half-life of the P sub(2U)R transcript in HL-60 cells was similar to 60 min, and this was not affected by acute exposure ( less than or equal to 4 hr) to Bt sub(2)cAMP or PMA. PMA down-regulated P sub(2U)R mRNA in THP-1 monocytes and HL-60 granulocytes but not in A431 human epithelial cells or human keratinocytes. P sub(2U)R mRNA was also down-regulated in THP-1 monocytes differentiated into inflammatory macrophages by gamma -interferon and endotoxin. These data indicate that myeloid leukocytes possess tissue-specific mechanisms for the rapid modulation of P sub(2U)R expression and function during differentiation and inflammatory activation.