Cyclic AMP phosphodiesterase activity during differentiation of rabbit erythroid bone marrow cells

Abstract

Changes in the activity of cyclic AMP phosphodiesterase during differentiation of rabbit bone marrow erythroid cells were investigated. The cells were separated by velocity sedimentation at unit gravity into six fractions corresponding to different stages of development: proerythroblasts, basophilic cells, polychromatic cells, early orthochromatic and late orthochromatic cells and reticulocytes. Cyclic AMP phosphodiesterase was found to be very active in the most immature cells, the proerythroblasts, which also have the highest content of cyclic AMP. After differentiation into basophilic erythroblasts, a 4-fold decrease in cyclic AMP phosphodiesterase activity was observed. In these cells the amount of cyclic AMP was about 80% lower than that in proerythroblasts. In polychromatic cells a further drop in phosphodiesterase activity occurred. After the final cell division the enzyme activity was very low and the levels of cyclic AMP in the early and late orthochromatic cells remained constant. Kinetic studies demonstrated a heterogeneity of erythroid cell cyclic AMP phosphodiesterase: high affinity, low-Km (5.5 X 10(-6) M) and low affinity, high-Km (0.1 X 10(-3) M) enzymes were found. The phosphodiesterase activity was dependent on the presence of Mg2+ and was activated by Ca2+ at low Mg2+ concentrations (1 mM). The changes in cyclic AMP phosphodiesterase activity during differentiation and maturation of erythroid cells suggest the possible importance of this enzyme in the physiological control of cyclic AMP concentrations in developing erythroblasts. The loss of cyclic AMP phosphodiesterase activity after cessation of cell division supports the concept of the significance of the final cell division in erythroblast differentiation.

Hydroxyurea nitrosylates and activates soluble guanylyl cyclase in human erythroid cells

“…5 During erythroid differentiation adenylate cyclase activity, cellular cAMP concentrations and cAMP phosphodiesterase activity have been reported to decline in a synchronized manner. 30 In addition to our findings in this and a previous publication, 4 there have been 2 reports of cAMP increasing HbF levels. Ikuta's group 31 has reported that expression of the gamma-globin gene is induced upon activation of the cAMP pathway, while Dover and colleagues 32 found that adenylate-cyclase inhibition markedly decreased HbF induction by hydroxyurea in human erythroid precursor cells.…”

Cyclic nucleotides and haemoglobin concentration in rabbit bone marrow cell suspensions stimulated by purified erythropoietin

“…Eight tubes, each containing 1 ml of cellular suspension in Hank solution (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) x lo6 nucleated cells), were placed in a thermostatic bath and incubated for four hours at 37°C. One ml Hank solution only was added to four tubes and used as controls, while 1 ml Hank solution containing one of the following test substances was added to the other four tubes:…”

Nitric Oxide / Cyclic Nucleotide Regulation of Globin Genes in Erythropoiesis

“…During erythroid differentiation adenylate cyclase and cAMP phosphodiesterase activity, as well as cellular cAMP concentrations, decline in a synchronized manner (Setchenska et al, 1981). The cAMP-dependent pathway plays a negative role in a Ǒ-globin gene expression in K562 erythroleukemic cell line, in contrast to a cGMP positive role (Inoue et al, 2004).…”