The Steroid/thyroid Hormone Receptor Superfamily

类固醇/甲状腺激素受体超家族

• 批准号: 6507331
• 负责人: Vera M Nikodem
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6507331
• 关键词: brain derived neurotrophic factor; developmental genetics; developmental neurobiology; dopamine; forskolin; gene expression; gene mutation; gene targeting; genetically modified animals; homeobox genes; in situ hybridization; laboratory mouse; mesencephalon; microarray technology; neurons; neurotransmitter biosynthesis; northern blottings; nuclear receptors; protein structure function; steroid hormone receptor; tegmentum; terminal nick end labeling; thyroid hormones; tissue /cell culture; transcription factor; tyrosine 3 monooxygenase

Nurr1 is a transcription factor, a member of the superfamily of nuclear hormone receptors. To investigate the physiological role of Nurr1, we previously generated mice with a null mutation in the Nurr1 gene. Subsequent analysis revealed the absence of neurotransmitter dopamine, dopamine biosynthesizing enzymes, transporters and receptors for dopamine utilization in the central dopaminergic area of newborn pups. We have also shown that the neuroepithelial cells undergo normal ventralization and migration. These dopaminergic neuron precursors express general neuronal markers such as a neuronal nuclear marker and project to the striatum. The TUNEL assay showed no difference in the number of apoptotic cells between Nurr1-null and wild type mice. Hence, our results show that the transcription factor Nurr1 is required for terminal maturation of mesencephalic dopaminergic neurons, while genesis of dopaminergic precursors, their survival, and selection of specific target innervation are not affected at the time of birth in mice lacking Nurr1 gene function. In order to investigate the role of Nurr1, a procedure for primary neuronal cultures was established. Recently, using primary midbrain neuronal cultures from newborn Nurr1 knockouts, we have shown that a population of neurons could be induced to express tyrosine hydroxylase, a key enzyme in dopamine biosynthesis, in the presence of forskolin with a synergistic increase in the number of tyrosine hydroxylase expression neurons when combined with brain-derived neurotrophic factor and dopamine. These data indicate that midbrain neurons from Nurr1 knockout pups retain the capacity for the induced expression of tyrosine hydroxylase even though in vivo tyrosine hydroylase expression is absent. Thus, the factors, such as forskolin, brain-derived neurotrophic factor, and dopamine induce tyrosine hydroxylase expression via a pathway independent of Nurr1. Recently, we have used DNA microarray technology and probes derived from the midbrain of the ventral tegmental area of wild type and Nurr1 knockout mice. We have identified 40 genes whose expression is affected by Nurr1. It appears that Nurr1 can function as a repressor and inducer of the expression of specific genes. Using independent methods (Northern analyses and in situ hybridization), we are comfirming changes in the expression of Nurr1 target genes. We have tested the wild type and Nurr1-null heterozygous mice for locomotor activity. Locomotor activity was recorded in a photocell monitor after exposure to novelty and saline injection. Nurr1 heterozygous mice displayed significantly greater motor activity in the novel open field and after saline injection. These data demonstrate that the loss of a single allele of Nurr1 gene results in alteration in motor activity in response to mild stress.

Nurr1是一种转录因子，是核激素受体超家族的成员。为了研究Nurr1的生理作用，我们先前在Nurr1基因中产生了无效突变的小鼠。随后的分析显示，在新生幼仔的中枢多巴胺能区域中缺乏神经递质多巴胺、多巴胺生物合成酶、转运蛋白和多巴胺利用受体。我们还发现，神经上皮细胞进行正常的腹侧化和迁移。这些多巴胺能神经元前体表达一般的神经元标记物，如神经元核标记物，并投射到纹状体。TUNEL检测显示Nurr1基因缺失小鼠和野生型小鼠之间的凋亡细胞数量没有差异。因此，我们的研究结果表明，转录因子Nurr1所需的中脑多巴胺能神经元的终端成熟，而多巴胺能前体的发生，他们的生存，并选择特定的目标神经支配在出生时没有Nurr1基因功能的小鼠不受影响。 为了研究Nurr1的作用，建立了原代神经元培养的程序。最近，使用原代中脑神经元培养新生儿Nurr1基因敲除，我们已经表明，一个人口的神经元可以诱导表达酪氨酸羟化酶，多巴胺生物合成的关键酶，在存在的毛喉素与协同增加的酪氨酸羟化酶表达神经元的数量时，结合脑源性神经营养因子和多巴胺。这些数据表明，中脑神经元从Nurr1基因敲除幼崽保留的能力，诱导表达的酪氨酸羟化酶，即使在体内酪氨酸羟化酶的表达是不存在的。因此，因子，如毛喉素，脑源性神经营养因子，多巴胺诱导酪氨酸羟化酶的表达通过一个独立的Nurr1的途径。 最近，我们使用了DNA微阵列技术和探针来自中脑腹侧被盖区的野生型和Nurr1基因敲除小鼠。我们已经确定了40个基因的表达受Nurr1的影响。Nurr1似乎可以作为特定基因表达的阻遏物和诱导物发挥作用。使用独立的方法（北方分析和原位杂交），我们正在确认Nurr1靶基因表达的变化。 我们已经测试了野生型和Nurr1缺失杂合子小鼠的自发活动。在暴露于新奇物和盐水注射后，在光电管监测器中记录运动活动。Nurr1杂合子小鼠在新的开放领域和盐水注射后显示出显着更大的运动活性。这些数据表明，Nurr1基因的单个等位基因的丢失导致响应于轻度应激的运动活动的改变。