Hildebrandt J P, Gerstberger R, Schwarz M
Physiologisches Institut, Medizinische Fakultät, Universität des Saarlandes, D-66421 Homburg/Saar, Germany.
Am J Physiol. 1998 Oct;275(4):C951-7. doi: 10.1152/ajpcell.1998.275.4.C951.
Osmotic stress in ducklings (Anas platyrhynchos) results in salt secretion and adaptive cell proliferation and differentiation in the nasal glands. We investigated whether osmotic stress in vivo or muscarinic ACh receptor activation in vitro changed the expression levels of the cellular protooncogene products Fos and Jun, which may play a role in the initiation of the adaptive processes. Using Fos- and Jun-specific polyclonal antisera in Western blot experiments, we demonstrated that Jun is constitutively expressed in nasal gland tissue, whereas Fos is not detectable in tissue from unstressed (naive) animals. Under conditions of osmotic stress imposed by replacing the drinking water of the animals with a 1% NaCl solution, Jun protein remains constant in nasal gland tissue, whereas Fos protein is transiently upregulated. Treatment of cultured nasal gland tissue with muscarinic agonists results in a transcriptionally regulated expression of Fos in an atropine-sensitive manner. Immunohistochemical experiments show that Fos accumulation occurs in the nuclei of the secretory cells. These results indicate that the activation of the c-fos gene induced by muscarinic ACh receptor-mediated signaling pathways may play an important role in the initiation of adaptive growth and differentiation processes in nasal glands of osmotically stressed ducklings.
雏鸭（绿头鸭）的渗透压应激会导致鼻腺分泌盐分，并引发适应性细胞增殖和分化。我们研究了体内渗透压应激或体外毒蕈碱型乙酰胆碱受体激活是否会改变细胞原癌基因产物Fos和Jun的表达水平，这可能在适应性过程的启动中发挥作用。在蛋白质印迹实验中使用Fos和Jun特异性多克隆抗血清，我们证明Jun在鼻腺组织中组成性表达，而在未受应激（未处理）动物的组织中检测不到Fos。在用1% NaCl溶液替代动物饮用水所施加的渗透压应激条件下，鼻腺组织中的Jun蛋白保持恒定，而Fos蛋白则短暂上调。用毒蕈碱激动剂处理培养的鼻腺组织会导致Fos以对阿托品敏感的方式进行转录调控表达。免疫组织化学实验表明，Fos在分泌细胞核中积累。这些结果表明，毒蕈碱型乙酰胆碱受体介导的信号通路诱导的c-fos基因激活可能在渗透压应激雏鸭鼻腺适应性生长和分化过程的启动中起重要作用。
