REGULATED EXOCYTOSIS IN DEVELOPING & NEOPLASTIC PANCREATIC ACINAR CELLS

我们项目的总体目标是确定分子基础 发育中胰腺调节分泌的生物发生。我们的 先前的研究表明，出生前1至2天，腺泡细胞 对促分泌剂刺激的反应与细胞内浓度的升高 第二个按摩器的水平，但不耦合这一事件与胞吐，尽管 胞外途径的所有细胞器都是 现在时。对激素刺激的调节胞吐作用变得 出生后大约24-48小时功能正常(分泌生成)。我们的 研究表明，分泌发生与Rab3D(A)的运动有关 酶原分泌发生的特异性标记与一种 在出生后24-48小时内出现戏剧性的但短暂的Rab4 与肌动蛋白末端共存的细胞顶端细胞质 纤网，而不是与分泌或内吞途径的膜。我们 假设Rab4的瞬时表达与 肌动蛋白“钳”的成熟可能是级联反应的最终事件 导致调节胞吐作用成熟的事件。我们打算 进一步推行这一制度，以确定责任因素 用于分泌生成。具体目标是(1)描述 Rb_3和Rb_4在多发性硬化症分泌发育中的生理学意义 关于磷酸化状态，与调节蛋白的相互作用 (例如，Rab GDI和可能参与肌动蛋白结合的蛋白质)，以及 调节分泌途径的细胞株AR42J的功能评价 可以由激素诱导，其中Rab蛋白的特定mRNAs 用反义核苷酸消除；(2)检测 其他小的GTP结合蛋白和SNARE家族成员，可能 在分泌发育过程中受到发育调节；(3)研究 在特定条件下器官培养中的分泌生成 确定候选激素对受调控细胞成熟的影响 分泌物；以及(4)检查腺泡细胞瘤和衍生的诱导物 AR42J细胞系，表现出正常产前的许多特性 Rab蛋白在胰腺中的表达和分布 正常的分泌生成。发育中的腺体与非发育性腺的比较 腺泡细胞瘤可能提供有关潜在缺陷的信息 这种大鼠肿瘤的形态特征和几种 人类胰腺癌的类型。

The overall goals of our project are to determine the molecular basis of the biogenesis of regulated secretion in the developing pancreas. Our previous work has shown that 1 to 2 days prior to birth, acinar cells respond to secretagogue stimulation with elevations of intracellular second massagers levels but do not couple this event to exocytosis despite the observation that all of the organelles of the exocytic pathway are present. Regulated exocytosis in response to hormonal stimulation becomes functional approximately 24-48 hours after birth (secretogenesis). Our studies show that secretogenesis is correlated with movement of rab3D (a marker exclusively for zymogen secretogenesis is associated with a dramatic but transient appearance of rab4 (24-48 hour postnatally) in the apical cytoplasm of the cell where it colocalizes with the actin terminal web and not with membranes of the secretory or endocytic pathway. We postulate that the transient expression of rab4 is related to the maturation of an actin "clamp" that may be a terminal event the cascade of events leading to the maturation of regulated exocytosis. We intend to pursue this system further in order to determine the factors responsible for secretogenesis. Specific aims are (1) to characterize the physiological significance of rab3 and rab4 during secretogenesis with regard to state of phosphorylation, interaction with regulatory proteins (e.g., rab GDI and proteins that may be involved in actin binding), and to evaluate function in cell line, AR42J whose regulated secretory pathway can be hormonally induced and in which specific mRNAs for rab proteins are eliminated with anti-sense nucleotides; (2) to examine the expression of other small GTP-binding proteins and members of the SNARE family that may be developmentally regulated during secretogenesis; (3) to study secretogenesis in organ culture under defined conditions in order to determine the effect of candidate hormones on maturation of regulated secretion; and (4) to examine an acinar cell tumor and a derived inducible cell line, AR42J, that exhibits many of the properties of normal prenatal pancreas for expression and distribution of rab proteins involved in normal secretogenesis. Comparison between the developing gland and the acinar cell tumor may provide information on the potential defects in secretion that characterize the morphology of this rat tumor and several types of human pancreatic cancer.