Screening of early neurodegeneration targets in brains of T2DM and obese mice and establishment of human iPSCs-derived astrocytes for in vitro experiments

• Grant number: 25/12864-7
• Support Opportunities: Scholarships abroad - Research Internship - Scientific Initiation
• Start date: September 29, 2025
• End date: January 28, 2026
• Field of knowledge: Biological Sciences - Biophysics - Biophysics of Processes and Systems
• Principal Investigator: Helena Cristina de Lima Barbosa
• Grantee: Isabela de Oliveira e Silva Campos Abreu
• Supervisor: Sovan Sarkar
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Institution abroad: University of Birmingham, England
• Associated to the scholarship: 24/21726-4 - The role of Wnt signaling in the regulation of GLUT1 and GLUT3 glucose transporters in the hypothalamus and hippocampus from prediabetic and obese C57BL/6 mice, BP.IC

Abstract

Alzheimer's disease (AD) is a major neurodegenerative condition linked not only to aging but also to external factors like obesity and Type 2 Diabetes Mellitus (T2DM). Key molecular markers include amyloid-beta (Abeta) plaques, neurofibrillary tangles (NFTs), and brain insulin resistance, which cause oxidative stress, synaptic failure, and neuronal death, leading to cognitive decline. Growing evidence supports the hypothesis that disruption of autophagy contributes to the accumulation of Abeta aggregates. To investigate early dysfunctions in neurodegeneration, our study focuses on Wnt proteins, which regulate synaptic plasticity, memory, and homeostasis in various tissues. Wnt signaling also controls glucose transporters (GLUTs) responsible for glucose uptake through the blood-brain barrier (BBB) and into neurons. Aging, obesity, and T2DM impair Wnt function, disrupting glucose uptake and BBB integrity, especially through astrocyte dysfunction. Impaired autophagy in glial cells reduces clearance of abnormal protein aggregates, causing excessive Abeta and NFT buildup, which activates glial cells and worsens neuronal loss. GSK-3beta, an inhibitor of Wnt/¿-catenin signaling, is increased in inflammation, hyperglycemia, and T2DM, affecting insulin signaling and glucose homeostasis. Our preliminary data show elevated GSK-3beta expression in the hippocampus of prediabetic mice, suggesting its role in early neurodegeneration, and there are also some studies suggesting GSK-3beta role in hippocampal autophagy promoted by insulin-deficient conditions. Thus, in this project we wish to further understand which Wnts are largely affected by aging, obesity and T2DM, and, with that knowledge, evaluate if and how the dysfunction of these proteins' signaling can cause glucose deficiency in the nervous system through the reduction of GLUT transporters. For that, we chose to use adult, obese and prediabetic mice, in order to evaluate if those conditions can promote, in the brain, typical modifications related to Alzheimer disease, such as the increase in GSK-3beta. Using immunofluorescence, we can analyze the location of glucose transporters GLUT1 and 3 in hippocampus, hypothalamus and BBB samples, as well as several markers of neurodegeneration in early stages, such as GSK-3beta. In addition, it would be in our research group's interest to learn and padronize techniques involving culture of induced pluripotent stem cells (iPSC), in order to perform analysis in patients derived neurons and astrocytes. This would allow a more vast and complex understanding of how BBB components suffer under oxidative stress. In conclusion, knowing that there is a direct correlation between the neurodegeneration associated with Alzheimer disease and deficient insulin signaling in the brain (mostly due to hypothalamic inflammation), and that this situation, similar to the one observed with T2DM, is related to a reduction in Wnt signaling, this work aims to elucidate some of the molecular details that connect the processes mentioned above. By understanding the molecular dysfunctions in the central nervous system, we can explore a new field of study, correlating Wnts, GLUTs, blood-brain barrier and insulin signaling, focusing not only in mitigating the neurodegeneration hallmarks, but also in possible therapies to alleviate and slow the disease's progression.