Functional Roles and Transcriptional Regulation of Cdkl2/KKIAMRE in Mouse Brain

在眨眼条件作用下，兔小脑深部核(DCN)中编码细胞周期蛋白依赖的类激酶2的CDKL2的转录增加。为了研究CDKL2在小鼠体内的表达模式及其活性依赖关系，我们利用基因打靶技术制备了编码外显子的氨基末端被LacZ取代的CDKL2突变小鼠。LacZ活性在出生后第3天至第7天(P3-P7)在大脑皮层中首次检测到，然后随着年龄的增加而逐渐增加，到P28时接近最高水平。在成人脑中，LacZ活性存在于嗅球、大脑皮层、海马体、丘脑核、杏仁核、膝状核、红核、小脑深部核、脑神经核和脊髓等不同脑区。Lurcher小鼠体内浦肯野细胞的丢失并不影响DCN中LacZ活性的模式和水平。谷氨酸、氯化钾、佛波酯和白血病抑制因子刺激原代神经元可显著增加c-Fos的水平，但对CDKL2转录本的作用不明显。这些结果表明，CDKL2主要在成熟神经元中发挥作用，在小鼠中调控该基因表达的机制与即刻早期基因的机制不同。

Transcripts of Cdkl2 encoding cycline-dependent kinase-like 2 increase in the deep cerebellar nuclei(DCN) of rabbits subjected to eyeblink conditioning. To examine the pattern of Cdkl2 expression and its activity dependence in mice, we prepared Cdkl2 mutant mice in which amino terminal coding exons were replaced by the LacZ using gene targeting. LacZ activity was first detected in the cerebral cortex from postnatal days 3 to 7 (P3-P7), and then gradually increased with age to reach nearly the maximal level by P28. In the adult brain, LacZ activity was detected in neurons in various brain regions including the olfactory bulb, cerebral cortex, hippocampus, thalamic nuclei, amygdaloid nuclei, geniculate nuclei, red nuclei, deep cerebellar nuclei, cranial nerve nuclei, and spinal cord. Loss of Purkinje cells in lurcher mice did not affect the pattern and level of LacZ activity in the DCN. Stimulation of primary neurons with glutamate, KCl, phorbol 12-myristate 13-acetate, and leukemia inhibitory factor appreciably increased the level of c-Fos but not of Cdkl2 transcripts. These results suggest that cdkl2 functions mainly in mature neurons and that mechanisms governing regulation of this gene expression in mice are distinct from those of immediate-early genes.