Down-Regulation of P2U-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; p. 97
• Main Authors: Martin, K A, Kertesy, S B, Dubyak, G R
• Format: Journal Article
• Language: English
• Published: United States American Society for Pharmacology and Experimental Therapeutics 01.01.1997
• Subjects: Bucladesine - pharmacology; Cell Differentiation; Cell Line; Down-Regulation; Gene Expression Regulation - drug effects; HL-60 Cells - metabolism; Humans; Interferon-gamma - pharmacology; Interleukin-1 - biosynthesis; Lipopolysaccharides - pharmacology; Polymerase Chain Reaction; Receptors, Purinergic P2 - genetics; RNA, Messenger - analysis; Tetradecanoylphorbol Acetate - pharmacology; Tumor Necrosis Factor-alpha - biosynthesis
• ISSN: 0026-895X; 1521-0111

HL-60 human promyelocytic leukocytes express G protein-coupled P 2U -purinergic nucleotide receptors (P 2U R or P2Y 2 R) that activate inositol phospholipid hydrolysis and Ca 2+ mobilization in response to ATP or UTP. We examined the expression of functional P 2U R and P 2U R mRNA levels during in vitro differentiation of HL-60 cells by dibutyryl-cAMP (Bt 2 cAMP), which induces a granulocyte/neutrophil phenotype, or by phorbol-12-myristate-13-acetate (PMA), which induces a monocyte/macrophage phenotype. Both P 2U R function and P 2U R mRNA levels were only modestly attenuated during granulocytic differentiation by Bt 2 cAMP. In contrast, P 2U R function, as assayed by either Ca 2+ mobilization or inositol trisphosphate generation, was greatly reduced in PMA-differentiated cells. This inhibition of P 2U R function was strongly correlated with PMA-induced decreases in P 2U R mRNA levels, as assayed by Northern blot analysis or reverse transcription-polymerase chain reaction-based quantification. Although PMA induced an early, transient up-regulation of P 2U R mRNA, this was rapidly followed by a sustained decrease in P 2U R mRNA to a level 5–10-fold lower than that in undifferentiated HL-60 cells. The half-life of the P 2U R transcript in HL-60 cells was ∼60 min, and this was not affected by acute exposure (≤4 hr) to Bt 2 cAMP or PMA. PMA down-regulated P 2U R mRNA in THP-1 monocytes and HL-60 granulocytes but not in A431 human epithelial cells or human keratinocytes. P 2U R mRNA was also down-regulated in THP-1 monocytes differentiated into inflammatory macrophages by γ-interferon and endotoxin. These data indicate that myeloid leukocytes possess tissue-specific mechanisms for the rapid modulation of P 2U R expression and function during differentiation and inflammatory activation.