Project description:During pregnancy, pancreatic islets undergo structural and functional changes that lead to enhance insulin release in response to increased insulin demand, which is rapidly reversed at parturition. One of the most important changes is expansion of pancreatic β-cell mass mainly by increased proliferation of β cells. We used microarrays to detail the global programme of gene expression and identified distinct up- or down-regulated genes during pregnancy. Maternal islet were isolated from mice at dpc 0 and 12.5 dpc of pregnancy for RNA extraction and hybridization on Affymetrix microarrays. We sought to identify the responsible factors for the proliferation of islets during pregnancy.
Project description:ABSTRACT:Pregnancy requires a higher functional beta cell mass and this is associated with profound changes in the gene expression profile of pancreatic islets. Taking Tph1 as a sensitive marker for pregnancy-related islet mRNA expression in female mice, we previously identified prolactin receptors and placental lactogen as key signalling molecules. Since beta cells from male mice also express prolactin receptors, the question arose whether male and female islets have the same phenotypic resilience at the mRNA level during pregnancy. We addressed this question in vitro, by using islet tissue culture with placental lactogen and in vivo, by transplanting male or female islets into female acceptor mice. Additionally, the islet mRNA expression of pregnant prolactin receptor deficient mice was compared with that of their pregnant wild-type littermates. When cultured with placental lactogen, or transplanted in female recipients that became pregnant (day 12.5), male islets induced the ‘islet pregnancy gene signature’, which we defined as the 12 highest induced genes in non-transplanted female islets at day 12.5 of pregnancy. In addition, serotonin immunoreactivity was also induced in these male transplanted islets at day 12.5 of pregnancy. In order to investigate the importance of prolactin receptors in these mRNA changes we used a prolactin receptor deficient mouse model. For the 12 genes of the signature, which are highly induced in control pregnant mice, no significant induction of mRNA transcripts was found at day 9.5 of pregnancy. Together, our results support the key role of placental lactogen as a circulating factor that can trigger the pregnancy mRNA profile in male and female beta cells. Islets were isolated from non-prengant (NP) and pregnant (day 9.5) PRLR+/+ and PRLR-/- mice for RNA extraction and hybridization on Affymetrix microarrays. For every condition 3 biological replicates were used.
Project description:During pregnancy, pancreatic islets undergo structural and functional changes that lead to enhance insulin release in response to increased insulin demand, which is rapidly reversed at parturition. One of the most important changes is expansion of pancreatic β-cell mass mainly by increased proliferation of β cells. We used microarrays to detail the global programme of gene expression and identified distinct up- or down-regulated genes during pregnancy.
Project description:ABSTRACT:Pregnancy requires a higher functional beta cell mass and this is associated with profound changes in the gene expression profile of pancreatic islets. Taking Tph1 as a sensitive marker for pregnancy-related islet mRNA expression in female mice, we previously identified prolactin receptors and placental lactogen as key signalling molecules. Since beta cells from male mice also express prolactin receptors, the question arose whether male and female islets have the same phenotypic resilience at the mRNA level during pregnancy. We addressed this question in vitro, by using islet tissue culture with placental lactogen and in vivo, by transplanting male or female islets into female acceptor mice. Additionally, the islet mRNA expression of pregnant prolactin receptor deficient mice was compared with that of their pregnant wild-type littermates. When cultured with placental lactogen, or transplanted in female recipients that became pregnant (day 12.5), male islets induced the ‘islet pregnancy gene signature’, which we defined as the 12 highest induced genes in non-transplanted female islets at day 12.5 of pregnancy. In addition, serotonin immunoreactivity was also induced in these male transplanted islets at day 12.5 of pregnancy. In order to investigate the importance of prolactin receptors in these mRNA changes we used a prolactin receptor deficient mouse model. For the 12 genes of the signature, which are highly induced in control pregnant mice, no significant induction of mRNA transcripts was found at day 9.5 of pregnancy. Together, our results support the key role of placental lactogen as a circulating factor that can trigger the pregnancy mRNA profile in male and female beta cells. The data obtained from the normal islets of pregnant mice (day12.5) was already described in Schraenen et al. 2010 (PMID: 20886204 and PMID: 20938637). Islets and islet grafts were isolated from non-prengant and pregnant mice for RNA extraction and hybridization on Affymetrix microarrays. For every condition, at least 3 biological replicates were used.
Project description:Pancreatic islets adapt to the increase in insulin demand during pregnancy by up-regulating beta cell proliferation, insulin synthesis, and lowering the threshold of glucose-stimulated insulin secretion. In vitro studies suggest that pregnancy hormones, such as placental lactogens and prolactin, both act through the prolactin receptor, are required for these adaptation. Furhtermore, we found that transgenic mice with heterogenous prolactin receptor null mutation are glucose intolerant, with a lower beta-cell mass and lower insulin levels. The goal here is to discover novel targets of prolactin receptor signaling in pancreatic beta cells during pregnancy.