Horiguchi Taigo, Fuka Miyuki, Fujisawa Koichi, Tanimura Ayako, Miyoshi Keiko, Murakami Ryutaro, Noma Takafumi
Department of Molecular Biology, Institute of Health Biosciences, the University of Tokushima Graduate School.
J Med Invest. 2014;61(1-2):137-50. doi: 10.2152/jmi.61.137.
Adenylate kinase isozyme 2 (AK2) is located in mitochondrial intermembrane space and regulates energy metabolism by reversibly converting ATP and AMP to 2 ADPs. We previously demonstrated that disruption of the Drosophila melanogaster AK2 gene (Dak2) resulted in growth arrest during the larval stage and subsequent death. Two other groups found that human AK2 mutations cause reticular dysgenesis, a form of severe combined immunodeficiency (SCID) that is associated with severe hematopoietic defects and sensorineural deafness. However, the mechanisms underlying differential outcomes of AK2 deficiency in Drosophila and human systems remain unknown. In this study, effects of tissue-specific inactivation of the Dak2 gene on Drosophila development were analyzed using RNAi-mediated gene knockdown. In addition, to investigate the roles of AK2 in the regulation of gene expression during development, microarray analysis was performed using RNA from first and second instar larvae of Dak2-deficient mutant and wild-type D. melanogaster. Knockdown of Dak2 in all germ layers caused cessation of growth and subsequent death of flies. Microarray analysis revealed that Dak2 deficiency downregulates various genes, particularly those involved in the proteasomal function and in mitochondrial translation machinery. These data indicate that adenine nucleotide interconversion by Dak2 is crucial for developmental processes of Drosophila melanogaster.
腺苷酸激酶同工酶2（AK2）位于线粒体外膜间隙，通过将ATP和AMP可逆地转化为2个ADP来调节能量代谢。我们之前证明，果蝇AK2基因（Dak2）的破坏导致幼虫期生长停滞并随后死亡。另外两个研究小组发现，人类AK2突变会导致网状发育不全，这是一种严重联合免疫缺陷（SCID）形式，与严重的造血缺陷和感音神经性耳聋有关。然而，果蝇和人类系统中AK2缺乏导致不同结果的潜在机制仍然未知。在本研究中，使用RNA干扰介导的基因敲低分析了Dak2基因的组织特异性失活对果蝇发育的影响。此外，为了研究AK2在发育过程中基因表达调控中的作用，使用来自Dak2缺陷型突变体和野生型黑腹果蝇的一龄和二龄幼虫的RNA进行了微阵列分析。在所有胚层中敲低Dak2会导致果蝇生长停止并随后死亡。微阵列分析显示，Dak2缺陷会下调各种基因，特别是那些参与蛋白酶体功能和线粒体翻译机制的基因。这些数据表明，Dak2介导的腺嘌呤核苷酸相互转化对黑腹果蝇的发育过程至关重要。
