Preliminary results: 1. We have found that insulin is significantly expressed at both mRNA and protein levels in human and mouse choroid plexus. The mouse insulin isoform mRNA levels in choroid plexus (CP) are about 10% of those of pancreas an unexpected finding. CP insulin content is the second highest among all tissues - second only to the usual pancreatic-derived insulin - and brain regions that we surveyed by RT-qPCR and in situ hybridization (ISH) techniques. 2. We have developed a proteomic panel to quantify separately and accurately alpha and beta subunits of insulin, as well as C- peptides derived from proinsulin, in CSF and plasma of human subjects. 3. We have discovered novel insulin promoters in human and mouse genome and the novel promoters are more active in brain CP than in pancreas. 4. In collaboration with HBCC-NIMH, we have identified that insulin is expressed in type 1 diabetes postmortem CP. 5. We have found that CP insulin levels are altered in 2XTG AD mouse model at presymptomatic stage (2 months of age) of amyloid deposition. Future: We will investigate for any CP-derived insulin association with AD pathology in collaboration with Dr. Juan Troncoso at Dept. of Pathology, JHMS who will collect post-mortem CP in different stages of AD prior to death and control samples. We will investigate CSF insulin levels in human AD vs controls samples. Mice have two insulin genes: Ins1 and Ins2. We have created Ins2-flox mice on the background of germline Ins1 knockout mice. This mouse line will be crossed with Foxj1-Cre-ERT-GFP mice to generate CP specific tamoxifen-inducible conditional knockout mice to study the function of CP insulin and its role in brain insulin resistance related to AD development. We will explore the potential of biologics to counteract insulin seeding as a cause of beta-amyloid oligomerization and plague formation. And, at a very basic level, we need to uncover what governs insulin synthesis and secretion in CP.
