Habekost, M. | Search bioRxiv

bioRxiv2024

APP and its intracellular domain modulate Alzheimers disease risk gene networks in transgenic APPsw and PSEN1M146I porcine models

Alzheimers disease (AD) is a progressive neurodegenerative disorder and the most frequent cause of dementia. The disease has a substantial genetic component comprising both highly penetrant familial mutations (APP, PSEN1, and PSEN2) and sporadic cases with complex genetic etiology. Mutations in APP and PSEN1/2 alter the proteolytic processing of APP to its metabolites, including A{beta} and APP Intracellular Domain (AICD). In this study, we use transgenic porcine models carrying the human APPsw and PSEN1M146I transgenes to demonstrate the pathobiological relevance of transcriptional regulation facilitated by APP and its AICD domain. Through molecular characterization of hippocampal tissue, we describe the differential expression of gene sets that cluster in molecular pathways with translational relevance to AD. We further identify phosphorylated and unphosphorylated AICD in differential complexes with proteins implicated in signal transduction and transcriptional regulation. Integrative genomic analysis of transcriptional changes in somatic cell cultures derived from pigs treated with {gamma}-secretase inhibitor demonstrates the importance of {gamma}-secretase APP processing in transcriptional regulation. Our data supports a model in which APP and, in particular, its AICD domain, modulates gene networks associated with AD pathobiology through interaction with signaling proteins. One Sentence SummaryUtilizing transgenic porcine models, our study reveals that Alzheimers disease-related mutations affect neuronal gene expression and highlights the role of the AICD domain of APP in modulating gene networks associated with Alzheimers pathobiology.

cell biology↗

bioRxiv2023

Injectable 3D microcultures enable intracerebral transplantation of mature neurons directly reprogrammed from patient fibroblasts

Direct reprogramming of somatic cells into induced neurons (iNs) has become an attractive strategy for the generation of patient-specific neurons for disease modeling and regenerative neuroscience. To this end, adult human dermal fibroblasts (hDFs) present one of the most relevant cell sources. However, iNs generated from adult hDFs using two-dimensional (2D) cultures poorly survive transplantation into the adult brain in part due to the need for enzymatic or mechanical cellular dissociation before transplantation. Three-dimensional (3D) culturing methodologies have the potential to overcome these issues but have largely been unexplored for the purposes of direct neuronal reprogramming. Here we report a strategy for direct in vitro reprogramming of adult hDFs inside suspension 3D microculture arrays into induced DA neurospheroids (iDANoids). We show that iDANoids express neuronal and DA markers and are capable of firing mature action potentials and releasing dopamine. Importantly, they can be gently harvested and transplanted into the brain of a Parkinsons disease rat model to reproducibly generate functionally integrated neuron-rich grafts. The 3D culturing approach presented here thus eliminates a major bottleneck in direct neuronal reprogramming field and, due to its simplicity and versatility, could readily be adapted as a culturing platform used for a broad range of transplantation studies as well as disease modeling.

neuroscience↗