Setchenska M S, Arnstein H R, Vassileva-Popova J G
Biochem J. 1981 Jun 15;196(3):887-92. doi: 10.1042/bj1960887.
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.
研究了兔骨髓红系细胞分化过程中环磷酸腺苷磷酸二酯酶活性的变化。通过单位重力下的速度沉降将细胞分离成六个对应于不同发育阶段的组分：原红细胞、嗜碱性细胞、多色性细胞、早幼正色细胞、晚幼正色细胞和网织红细胞。发现环磷酸腺苷磷酸二酯酶在最不成熟的细胞即原红细胞中非常活跃，原红细胞中环磷酸腺苷的含量也最高。分化为嗜碱性成红细胞后，观察到环磷酸腺苷磷酸二酯酶活性下降了4倍。在这些细胞中，环磷酸腺苷的量比原红细胞中低约80%。在多色性细胞中，磷酸二酯酶活性进一步下降。在最后一次细胞分裂后，酶活性非常低，早幼正色细胞和晚幼正色细胞中环磷酸腺苷的水平保持恒定。动力学研究表明红系细胞环磷酸腺苷磷酸二酯酶具有异质性：发现了高亲和力、低Km（5.5×10⁻⁶M）和低亲和力、高Km（0.1×10⁻³M）的酶。磷酸二酯酶活性依赖于Mg²⁺的存在，并且在低Mg²⁺浓度（1mM）下被Ca²⁺激活。红系细胞分化和成熟过程中环磷酸腺苷磷酸二酯酶活性的变化表明该酶在发育中的成红细胞中环磷酸腺苷浓度的生理控制中可能具有重要作用。细胞分裂停止后环磷酸腺苷磷酸二酯酶活性的丧失支持了最终细胞分裂在成红细胞分化中的重要性这一概念。
