CELLULAR BASIS OF ACTION OF GASTROINTESTINAL PEPTIDES

蛙皮素和CCK相关多肽广泛存在于胃肠道和中枢神经系统中，但它们的细胞作用基础尚不清楚，尤其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CCK受体[CCK-A-R]的细胞作用基础正在研究中。一种新的蛙皮素受体，已在两栖动物中描述，蛙皮素受体亚型-4[BB-4-R]，并在去年成功地在哺乳动物细胞CHO-K-1中稳定表达，这使得首次对其细胞生物学和药理学进行研究。我们的研究表明，该受体与磷脂酶C偶联，通过激活刺激(Ca-2+)-和肌醇磷酸盐的变化，以及与磷脂酶D偶联[生物化学38：7307,1999]。在以前的研究中，CCK-A-R的激活与磷脂酶C的激活、细胞内[Ca-2+]的动员以及PKC、PLD和PLA-2的激活相耦合。我们最近的研究(Adv.Mol.牢房。恩德里奥尔。3,119,1999)和其他人表明酪氨酸磷酸化增加也可能是一个重要的细胞级联反应。我们已经证明了CCK-A-R导致p125粘着斑激酶和巴西林的酪氨酸磷酸化，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(生化38：1497,1999)。我们发现CCK通过依赖于PLC和依赖于小G蛋白p21-Rho和肌动蛋白细胞骨架的完整性的独立途径快速地使p130-cas(Crk相关底物)酪氨酸磷酸化。该通路的激活导致p130-CaS转位至细胞膜，并与c-Crk偶联。由于p130-CaS是一种主要的细胞内适配分子，具有大量的SH-3和SH-2结合域，与Crk一样，并且具有分子开关的功能，因此它的激活可能是CCK下游效应，特别是生长的重要中介。-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,