Regulation of brain insulin mRNA by glucose and glucagon-like peptide 1

G Madadi, PS Dalvi, DD Belsham - Biochemical and biophysical research …, 2008 - Elsevier
G Madadi, PS Dalvi, DD Belsham
Biochemical and biophysical research communications, 2008Elsevier
Whether the brain synthesizes insulin is currently debated. Two clonal, immortalized mouse
hypothalamic cell lines from e17, mHypoE-39 and mHypoE-46, express insulin 2 (Ins2), but
not Ins1. We analyzed regions necessary for basal gene activity and found that the mouse
Ins2 region− 110/+ 183bp stimulates promoter activity in hypothalamic neurons. The rat Ins2
showed moderate activity, whereas the human promoter construct is repressed below basal
levels. In MIN6 pancreatic β-cells, all of the Ins1 and Ins2 promoter constructs display high …
Whether the brain synthesizes insulin is currently debated. Two clonal, immortalized mouse hypothalamic cell lines from e17, mHypoE-39 and mHypoE-46, express insulin 2 (Ins2), but not Ins1. We analyzed regions necessary for basal gene activity and found that the mouse Ins2 region −110/+183bp stimulates promoter activity in hypothalamic neurons. The rat Ins2 showed moderate activity, whereas the human promoter construct is repressed below basal levels. In MIN6 pancreatic β-cells, all of the Ins1 and Ins2 promoter constructs display high levels of transcriptional activity. The cell lines also express components of glucose-sensing machinery and the endogenous glucagon-like peptide 1 receptor (Glp-1R). We observed that 16.7mM glucose induces Ins2 mRNA, while forskolin and a Glp-1 agonist, exendin-4, induce a biphasic Ins2 mRNA response in mHypoE-39 neurons. The insulin cis-regulatory regions differ between the pancreas and the hypothalamus, and glucose and Glp-1 regulate the expression of hypothalamic insulin.
Elsevier