Effect Of Wnt/β-catenin Pathway In Pancr Eatic Cell Adabtive Prolifer Ation During Pregnancy In Rats And In Vitro

Objectives:1. To investigate the profiles of islet gene expression at various stages of pregnancy in rats, and screen the key genes of Wnt pathway relevant to islet proliferation.2. To elucidate the expression and implication of key genes of Wnt pathway in pancreatic islet cell of pregnant rats and in prolactin treated INS-1 cell line in vitro.Methods:1. Pancreatic islets of SD rats during pregnancy at day 10.5, 14.5 and non-pregnant female rats were isolated and purified, respectively.2. Gene chips from Affymetrix company were applied to explore gene expression profiles of islet at various stages of pregnancy in rats. Data, especially those of Wnt signaling genes related to islet proliferation, were analyzed.3. Wnt signaling genes related to islet proliferation were studied by RT-PCR and Western blotting to verify the results of gene chips.4. INS-1 cell proliferation was assessed by MTT colorimetric assay.5. Key genes of Wnt signaling in INS-1 cell line cultured with prolactin for various periods were studied by Western blotting.Results:1. There were 31099 known or unknown genes included in the Affymetrix Rat Genome 230 2.0 Array. The detection rates in such groups as normal female rats (N), pregnant rats at day 10.5 (P10.5) and day 14.5 (P14.5) were 45.3%, 38.2% and 37.2%, respectively. Compared with normal controls, the expression of genes of Wnt signaling pathway was changed during pregnancy.3. Compared with normal control group, the expressions of Wnt signaling pathway genes such asβ-catenin, c-Myc were up-regulated during pregnancy.β-catenin and c-Myc mRNA reached a peak level at P14.5.β-catenin and c-Myc proteins were also increased during pregnancy, with a peak expression at P14.5.4. After cultured with PRL(50~1000ng/ml), the proliferation of INS-1 cells was increased in a dose-dependent manner. Expressions ofβ-catenin and c-Myc protein were also increased significantly followed by enhanced cell proliferation.Conclusions:1. Wnt/β-catenin signaling pathway is involved in the process of morphological change of pancreatic islets during pregnancy.2. Expressions of key genes of Wnt/β-catenin signaling pathway were increased during pregnancy, suggesting that they may participate in regulating adaptive proliferation of pancreatic islets during pregnancy in rats.3. Wnt/β-catenin signaling pathway plays an important role in prolacin-induced pancreaticβ-cell growth in vitro.