Induction of cAMP-dependent protein kinase I during human monocyte differentiation.

Differentiation of human peripheral blood monocytes into macrophages was accompanied by induction of the regulatory subunit of cAMP-dependent protein kinase I as determined by photoaffinity labeling of cytosol proteins with 8-N3-[32P]cAMP and DEAE-Sephacel chromatography. The appearance of cAMP-dependent protein kinase I in macrophages was not due to translocation from the particulate fraction of monocytes. The regulatory subunit of cAMP-dependent protein kinase II was present in both monocytes and in vitro-differentiated macrophages. Protein kinase I in macrophages demonstrated higher affinity for 8-N3-cAMP (KD = 0.7 nM) than did protein kinase II from either monocytes (KD = 14.5 nM) or macrophages (KD = 4.9 nM). These studies demonstrate induction of the regulatory subunit of cAMP-dependent protein kinase I during the differentiation of a normal human cell and support the hypothesis that cAMP may regulate some stages of differentiation.