Research for modulation of expression of serotonin transporter and its involvement in mental disorder

我们研究了5-羟色胺转运体的调节机制以及5-羟色胺转运体(SET)在抑郁症中的作用，以阐明SET在精神障碍中的功能作用。SET的磷酸化调控。用佛波酯激活蛋白激酶C或用花盏花素A抑制蛋白磷酸酶来调节COS7细胞中SET的表达。两种处理均可降低SET活性，降低Vmax，但对Km无影响。对SET中5个可能的PKC磷酸化位点的定点突变表明，这些对SET活性的抑制调控不是通过PKC.2对SET的直接磷酸化起作用的。免疫细胞化学方法检测SET的细胞定位和细胞内定位。SET定位于静脉曲张神经纤维和神经末梢，但不定位于胞体。在电子显微镜下，突触小泡和突触前膜周围均可见SET。α-干扰素和-γ干扰素对SET转录的影响：α-干扰素和-γ干扰素作用3h后，SET mRNA和SET活性均升高，二丁酰cAMP也使SET mRNA和SET活性增加。干扰素作用3h后，小鼠中脑和肾上腺中SET mRNA水平均升高，提示干扰素引起的精神副反应是通过调节5-羟色胺转运体转录而产生的，5-羟色胺转运体转录调控可能是情感性精神障碍的神经化学机制之一。

We examined the regulatory mechanism of serotonin transporter and the involvement of serotonin transporter (SET) in depression to elucidate the function role of SET in mental disorder.1. Regulation of SET by phosphorylation. The regulation of SET expressed in COS7 cells by the activation of protein kinase C with phorbol ester or by inhibition of protein phosphatases with calyculin A was examined. Both treatment decreased the activity of SET with a reduction in Vmax without affecting Km. Site-directed mutagenesis of five putative PKC phosphorylation sites in SET revealed that these inhibitory modulation of SET activity did not act via direct phosphorylation of SET by PKC.2. Immunocytochemical localization of SET.The cellular and intracellular localization of SET was examined by immunocytochemistry. SET was localized in the varicose nerve fibers and nerve terminals but not in the cell bodies. Under electron microscopy, SET was seen around the synaptic vesicles as well as presynaptic membrane.3. The effects of interferon-alpha and -gamma on the transcription of SET.Both SET mRNA and SET activity were increased by treatment with interferon-alpha and -gamma for 3 h. Treatment with dibutyryl cAMP also increased SET mRNA and SET activity. The level of SET mRNA was increased both in the midbrain and adrenal glands of mice which were treated with interferons for 3 h. These results suggest that the interferon-induced psychiatric side effects arise through regulation of serotonin transporter transcription and that the transcriptional regulation of the serotonin transporter is a possible neurochemical mechanism of affective disorders.