CHARACTERIZATION OF NEW TGF BETA FROM DROSOPHILA

正常的生长和分化过程需要一套复杂而精细的控制，以确保只有正确的细胞子集接收到分裂和变化的信号。很多时候，信号由一组细胞产生并扩散到接收细胞。一组重要的弥漫性信号分子是转化生长因子β (tgf - β)超家族。这个家族的40多个成员已经被确定，它们负责模式形成、组织生长、骨形态发生和分化的许多其他方面，这个家族的成员是如此保守，以至于果蝇的蛋白质在体内被证明可以替代大鼠的同源物。有趣的是，这个家族的成员对于正常的神经发生和预防神经变性也很重要。我们已经从果蝇中分离出一种编码tgf - β的cDNA。Northern blot分析表明产生了两种信息，一种是头部特有的，另一种是眼睛特有的。我们不知道这是由于选择性剪接还是两个重叠的信息。开放阅读框编码一种310个氨基酸的蛋白质，接近这个家族的“典型”大小。在202位有一个用于裂解的RXXR信号序列，这也是tgf - β的典型序列和位置。裂解后释放的活性肽与猪激活素的相似性为32%，与人tgf - β 1的相似性为27%。虽然这似乎很难确定一个家族的成员，但tgf - β家族的标志是7个半胱氨酸以不变的模式间隔。这些半胱氨酸参与形成一种结构，这种结构存在于tgf - β家族、PDGF家族成员和NGF家族成员中，被称为半胱氨酸结。这些半胱氨酸，结合一些保守的脯氨酸和甘氨酸，清楚地表明Z33是这一重要信号分子的成员。我们将描述该基因在整个发育过程中的表达模式。我们将通过产生表达减少或增加的果蝇来确定其功能，并观察果蝇的生理是如何改变的，特别关注眼睛的发育。由于这个家族的成员在进化上是保守的，很可能存在一个人类同源基因，无论在果蝇中了解到什么，都将直接影响人类的生长信号和相关疾病。

The normal course of growth and differentiation requires a complex and delicate set of controls to be sure that only the correct subset of cells receive the signal to divide and change. Many times, the signal is produced by one set of cells and diffuses to the recipient cells. One important group of diffusive signaling molecules is the Transforming Growth Factor Beta (TGF-beta) superfamily. Over forty members of this family have been identified and are responsible for pattern formation, tissue growth, bone morphogenesis and many other aspects of differentiation Members of this family are so conserved that Drosophila proteins have been shown to be substitutable for rat homologues in vivo. Interestingly, members of this family are also important for proper neurogenesis and prevention of neural degeneration. We have isolated a cDNA from Drosophila which encodes a putative TGF-beta. Northern blot analysis indicates two messages are produced, one is head-specific, the other is eye specific. We do not know if this is due to alternative splicing or two overlapping messages. The Open Reading Frame encodes a 310 amino acid protein, which is near the "typical" size of this family. There is an RXXR signal sequence for cleavage at position 202, which is also the typical sequence and position for a TGF-beta. The putative active peptide which would be released by this cleavage shares 32% similarity with Porcine activin and 27% similarity with human TGF-beta 1. Although this seems low to identify a member of a family, the hallmark of the TGF-beta family is seven cysteines spaced in an invariant pattern. These cysteines are involved in formatting a structure found in the TGF-beta family, in members of the PDGF family and members of the NGF family called the cysteine knot. These cysteines, combined with some conserved Prolines and glycines clearly show that Z33 is a member of this important of signaling molecules. We will characterize the expression pattern of this gene throughout development. We will ascertain its function by generating flies with reduced or increased expression and seeing how the flies' physiology is altered with special attention focused on development in the eye. Since members of this family are evolutionarily conserved, it is very likely that a human homologue exists and whatever is learned about this gene in Drosophila will have direct bearing on human growth signaling and related diseases.