A novel cellular model of entorhinal cortex layer II vulnerability in alzheimer's disease

The National Institute on Aging awarded Boston University Medical Campus $110,228 in project grant funding on February 7, 2027, to develop and validate a novel cellular model of entorhinal cortex layer II vulnerability in Alzheimer's disease under the Aging Research program (CFDA 93.866).

The project will develop in vitro models using induced pluripotent stem cells (iPSCs) and direct fibroblast conversion to generate entorhinal cortex layer II (ECII)-like neurons for studying Alzheimer's disease pathology. Aim 1 will characterize how biological age influences tau pathology by comparing pathological tau emergence in ECII-like neurons derived from fibroblasts obtained from donors ranging from 22 to 59 years old at the time of sampling. Aim 2 will use iPSC-derived ECII-like neurons to characterize additional Alzheimer's disease-associated mechanisms. The model addresses a gap in current research: most animal models fail to replicate early pathological processes, and in vitro studies typically examine generic neuron populations rather than subtype-specific neurons, obscuring the unique molecular mechanisms underlying ECII neuron vulnerability to tau aggregation and neuronal death.

Work is performed in Roxbury, Massachusetts. The period of performance runs from February 7, 2027, through August 18, 2030. This is a project grant, a form of assistance typical for basic and applied research in aging and dementia.

Abstract

In alzheimer's disease (ad), symptom-associated brain pathology develops first in neurons from layer II of the entorhinal cortex (ecii), beginning with the aggregation of hyperphosphorylated TAU and neuronal death. While the selective formation of pathological TAU in ecii neurons and their subsequent degeneration remain the most reliable molecular correlates for cognitive decline and other clinical symptoms of ad, the critical question of why ecii neurons are selectively vulnerable remains understudied. Most animal models fail to replicate early pathological processes, and in vitro studies commonly examine generic neuron populations rather than subtype- specific neurons, obscuring the unique molecular mechanisms that contribute to early ad vulnerability. We have previously identified in silico a transcription factor that drives the differentiation of induced pluripotent stem cells (ipscs) into ecii-like neurons. Here, we will demonstrate the application of this novel ecii model for the study of ad and neuronal vulnerability, by examining how known ad risk factors influence TAU pathology in vitro. In aim 1, we will characterize how biological age influences different aspects of TAU pathology, as aging represents the strongest risk factor for ad. Ipscs are reverted to a younger epigenetic state during production, erasing aging-associated signatures; however, dermal fibroblasts present a biological age reflective of the age of the donor, both before and after direct conversion to other cell types. By adapting our ecii model for the direct conversion of fibroblasts to ecii-like neurons, we will be able to compare the emergence of pathological TAU marks in ecii-like neurons derived from fibroblasts obtained from donors ranging from 22 to 59 years of age at the time of sampling. In aim 2, we will use ipsc-derived ecii-like neurons to characterize an ad-associated genetic variant in endocytic recycling gene SNX31, whose expression is increased in entorhinal cortex neurons during presymptomatic ad. The SNX31 RS1693551 variant is genome-wide significantly associated with ad, and SNX31 itself has been associated with ad risk. We will determine the effects of this genetic variant on SNX31 mrna transcription/splicing and protein localization/function, and examine how the variant may impact TAU pathology downstream of the ad-protective and ecii-enriched reln signaling pathway in vitro. This will demonstrate the utility of our ecii model in investigating the molecular mechanisms underlying neuronal genetic variants linked with ad. Together, these aims will produce the first disease-relevant cellular model with which to study ad pathogenesis in vitro, shed vital insights into the molecular and cellular pathways underlying selective vulnerability in ad, and create a new platform to aid in future research identifying new therapeutic targets or diagnostic markers. Our proposed plan also provides an opportunity for diverse training in neuroscience and neurodegenerative disease, which will hone the skills required for success as an independent physician-scientist.