CELLULAR BASIS OF ACTION OF GASTROINTESTINAL PEPTIDES

蛙皮素和CCK相关肽广泛存在于胃肠道和中枢神经系统，然而，它们的细胞作用基础方面仍不清楚，特别是酪氨酸磷酸化在其信号级联中的作用。在我们最近的研究中，蛙皮素受体和胆囊收缩素-A（CCK）受体[CCK-A-R]的细胞作用基础正在研究中。在两栖动物中描述的一种新的蛙皮素受体，蛙皮素受体亚型-4 [BB-4-R]，在过去的一年中，它已在哺乳动物细胞CHO-K-1中成功稳定表达，这使得其细胞生物学和药理学首次得到研究。我们的研究表明，该受体与磷脂酶C偶联，活化刺激（Ca-2+），-和肌醇磷酸的变化，以及与磷脂酶D偶联[Biochemistry 38：7307，1999]。在先前的研究中，CCK-A-R激活已显示与磷脂酶C的激活以及细胞[Ca-2+]的动员以及PKC、PLD和PLA-2的激活偶联。我们最近的研究（Adv. Mol. Cell.异狄诺3，119，1999）等显示增加的酪氨酸磷酸化也可能是重要的细胞级联。我们已经证明CCK-A-R引起p125粘着斑激酶和桩蛋白的酪氨酸磷酸化，并且在今年的一项研究中证明它也引起p130-cas的酪氨酸磷酸化（Biochemistry 38：1497，1999）。我们发现CCK通过PLC依赖性和独立性途径使p130-cas（Crk相关底物）快速酪氨酸磷酸化，该途径依赖于小G蛋白、p21-rho和肌动蛋白细胞骨架的完整性。该途径的激活导致p130-cas易位到质膜并与c-CrK偶联。由于p130-cas是一种主要的细胞内衔接分子，具有众多的SH-3和SH-2结合结构域，如CrK，并作为分子开关，其激活表明它可能是CCK下游效应的重要介体，特别是生长。- 蛙皮素受体，CCK受体，p125-FAK，p130-cas，

Bombesin- and CCK-related peptides are found widely in the gastrointestinal (GI) tract and central nervous system, however, aspects of their cellular basis of action remain unclear, particularly the role of tyrosine phosphorylation in their signaling cascade. In our recent studies the cellular basis of action of bombesin receptors and cholecystokinin-A (CCK) receptors [CCK-A-R] are being examined. A new bombesin receptor that has been described in amphibians, bombesin receptor subtype-4 [BB-4-R] and during this last year it has been successfully stably expressed in a mammalian cell, CHO-K-1 which allows its cell biology and pharmacology to be studied for the first time. Our studies demonstrate this receptor is coupled to phospholipase C with activation stimulating both changes in (Ca-2+),-and inositol phosphates, as well as being coupled to phospholipase D [Biochemistry 38:7307, 1999.] In previous studies CCK-A-R activation has been shown to be coupled to activation of phospholipase C with mobilization of cellular [Ca-2+], and activation of PKC, PLD, and PLA-2. Recent studies by us (Adv. Mol. Cell. Endrinol. 3, 119, 1999) and others show increased tyrosine phosphorylation may also be an important cellular cascade. We have demonstrated CCK-A-R causes tyrosine phosphorylation of p125 focal adhesion kinase and paxillin and in a study this year demonstrated it also caused tyrosine phosphorylation of p130-cas (Biochemistry 38:1497, 1999). We found rapid tyrosine phosphorylation of p130-cas (Crk-associated substrate) by CCK through PLC dependent-and independent pathways that was dependent on the small G protein, p21-rho and the integrity of the actin cytoskeleton. Activation of this pathway resulted in the translocation of p130-cas to the plasma membrane and coupling to c-CrK. Because p130-cas is a major intracellular adapter molecule with both numerous SH-3 and SH-2 binding domains, as is CrK, and functions as a molecular switch, its activation suggests it may be an important mediator of CCKs downstream effects, especially growth. - bombesin receptors, CCK receptors, p125-FAK, p130-cas,