Kölsch Verena, Paululat Achim
Universität Marburg, Fachbereich Biologie-Entwicklungsbiologie, Karl von Frisch Strasse, 35032 Marburg, Germany.
Dev Genes Evol. 2002 Nov;212(10):473-85. doi: 10.1007/s00427-002-0268-6. Epub 2002 Sep 21.
The highly conserved basic helix-loop-helix transcription factor Hand plays a crucial role in cardiogenesis, limb formation and other developmental processes of vertebrates. Humans, mice and other higher vertebrates have two related genes, dHand (also known as Hand2, Hed, Thing2) and eHand (also known as Hand1, Hxt, Thing1), whereas fish and Drosophila have only a single hand gene. We cloned Drosophila hand and studied the embryonic expression in detail by using various tissue-specific markers that allowed us to analyze the identity of hand-expressing cells. We found hand to be expressed in the entire heart, including all cardioblasts and pericardial cells, in the progenitors of the circular visceral muscles, the lymph gland and garland cells, and in a few cells in the CNS. The expression of Drosophila hand starts after the inductive activity of the early regulators in these tissues, e.g. Tinman and Bagpipe, suggesting a role of Hand in differentiation rather than in tissue determination. In many aspects the expression pattern of Drosophila hand resembles the patterns of its vertebrates orthologues, for instance in cardiac tissues. We assume that Hand proteins might play a highly conserved role throughout evolution.
高度保守的碱性螺旋-环-螺旋转录因子Hand在脊椎动物的心脏发生、肢体形成及其他发育过程中发挥着关键作用。人类、小鼠及其他高等脊椎动物有两个相关基因，即dHand（也称为Hand2、Hed、Thing2）和eHand（也称为Hand1、Hxt、Thing1），而鱼类和果蝇只有一个hand基因。我们克隆了果蝇的hand基因，并通过使用各种组织特异性标记物详细研究了其胚胎表达情况，这些标记物使我们能够分析表达hand基因的细胞的特性。我们发现hand基因在整个心脏中表达，包括所有的成心肌细胞和心包细胞，在内脏环形肌的祖细胞、淋巴腺和花环细胞中表达，以及在中枢神经系统的少数细胞中表达。果蝇hand基因的表达在这些组织中早期调节因子（如Tinman和Bagpipe）的诱导活性之后开始，这表明Hand在分化而非组织决定中起作用。在许多方面，果蝇hand基因的表达模式类似于其脊椎动物同源物的模式，例如在心脏组织中。我们认为Hand蛋白在整个进化过程中可能发挥着高度保守的作用。
