Skoglund G, Basmaciogullari A, Rouot B, Marie J C, Rosselin G
Unité de Recherche sur les Peptides Neurodigestifs et le Diabète, Institut National de la Santé et de la Recherche Médicale, Unité 55, 75571 Paris Cedex 12, France.
J Endocrinol. 1999 Jul;162(1):31-7. doi: 10.1677/joe.0.1620031.
G protein alpha-subunits are involved in the transduction of receptor-mediated regulation of insulin and glucagon secretions. To get further insight into the status of G proteins in alpha- and beta-cells of the Langerhans islets, we have used immunohistochemistry to study the distribution of alpha-subunits in pancreas sections from the rat. Our results show that only insulin-immunoreactive beta-cells display immunoreactivity for selective antibodies directed against the different members of the Galphas and Galpha12-families (alphas, alphaolf, and alpha12, alpha13 respectively). Immunoreactivities for antibodies directed against members of the Galphaq- and Galphai-families showed a more diverse localization: alpha11 and alphao2 were only detected in glucagon-immunoreactive alpha-cells, whereas alphai1 was detected in all beta-cells but only in a few alpha-cells. Even though beta-cells showed immunoreactivities for alphao-non-isoform-selective antibodies, we could not identify the isoform(s) present using selective alphao1 and alphao2 antibodies. Other members of the Galphai- and Galphaq-families (alphai3, alphat2, alphaz and alphaq) were detected in both alpha- and beta-cells. In conclusion, our findings demonstrate a clear difference in the localization of G protein alpha-subunits between alpha- and beta-cells, suggesting the involvement of specific receptor transduction pathways for the neuronal/hormonal regulation of alpha- and beta-cell functions.
G蛋白α亚基参与受体介导的胰岛素和胰高血糖素分泌调节的转导过程。为了更深入了解朗格汉斯胰岛α细胞和β细胞中G蛋白的状态，我们采用免疫组织化学方法研究了大鼠胰腺切片中α亚基的分布。我们的结果显示，只有胰岛素免疫反应性β细胞对针对Gαs和Gα12家族不同成员（分别为αs、αolf和α12、α13）的选择性抗体呈现免疫反应性。针对Gαq和Gαi家族成员的抗体的免疫反应性显示出更多样化的定位：α11和αo2仅在胰高血糖素免疫反应性α细胞中检测到，而αi1在所有β细胞中检测到，但仅在少数α细胞中检测到。尽管β细胞对αo非异构体选择性抗体呈现免疫反应性，但我们使用选择性αo1和αo2抗体无法鉴定出存在的异构体。Gαi和Gαq家族的其他成员（αi3、αt2、αz和αq）在α细胞和β细胞中均有检测到。总之，我们的研究结果表明α细胞和β细胞中G蛋白α亚基的定位存在明显差异，提示特定受体转导途径参与α细胞和β细胞功能的神经/激素调节。
