Tischler A S, Riseberg J C, Hardenbrook M A, Cherington V
Department of Pathology, Tufts University School of Medicine, Boston, Massachusetts 02111.
J Neurosci. 1993 Apr;13(4):1533-42. doi: 10.1523/JNEUROSCI.13-04-01533.1993.
Adult rat chromaffin cells in vitro show a large proliferative response to NGF, followed by neuronal differentiation. Infection of replicating chromaffin cells with a retrovirus carrying the Escherichia coli beta-galactosidase (beta-gal) gene demonstrates beta-gal expression in cells that continue to multiply, that differentiate into neurons, and that become static. The effects of NGF on proliferation and differentiation are abolished by the protein kinase inhibitors K252a and staurosporine, and by cholera toxin, an activator of adenylate cyclase. They are diminished, but not abolished, by high concentrations of dexamethasone. Both cholera toxin alone and phorbol myristate acetate (PMA), an activator of protein kinase C, elicit small and inconsistent mitogenic responses. The responses to PMA cannot be shown to be additive with the effects of NGF. NGF is a known mitogen and neuritogen for chromaffin cells from neonatal rats, but has not previously been believed to affect similarly chromaffin cells from adults. The present findings suggest that portions of NGF signaling pathways might continue to be involved in regulating proliferation of adult rat chromaffin cells in vivo, and might be constitutively activated in PC12 cells and other adrenal medullary tumors. They further suggest that rat chromaffin cells might be propagated in vitro to obtain large numbers of sympathetic neurons expressing normal or exogenous genes.
体外培养的成年大鼠嗜铬细胞对神经生长因子（NGF）表现出强烈的增殖反应，随后发生神经元分化。用携带大肠杆菌β-半乳糖苷酶（β-gal）基因的逆转录病毒感染正在复制的嗜铬细胞，结果显示在持续增殖、分化为神经元以及静止的细胞中均有β-gal表达。蛋白激酶抑制剂K252a和星形孢菌素以及腺苷酸环化酶激活剂霍乱毒素可消除NGF对增殖和分化的影响。高浓度地塞米松可使其作用减弱，但不会消除。单独使用霍乱毒素以及蛋白激酶C激活剂佛波酯（PMA）均可引发微弱且不一致的促有丝分裂反应。无法证明PMA的反应与NGF的作用具有叠加性。NGF是新生大鼠嗜铬细胞已知的促有丝分裂剂和神经突生长因子，但此前一直认为它对成年大鼠嗜铬细胞的影响不同。目前的研究结果表明，NGF信号通路的某些部分可能继续参与体内成年大鼠嗜铬细胞增殖的调节，并且可能在PC12细胞和其他肾上腺髓质肿瘤中持续激活。这些结果还表明，可以在体外培养大鼠嗜铬细胞，以获得大量表达正常或外源基因的交感神经元。
