Sexual dimorphic cell type and connectivity atlases of the aging and AD mouse brains

项目摘要

Project Abstract In response to NOT-21-039 and related PAR-22-093, we propose this project to address several urgent needs in the field. Mouse models spanning different ages and sexes are routinely used to quantify anatomic, molecular, and pathologic changes in neurodegenerative diseases like Alzheimer’s Disease (AD). Yet, the only available standard mouse brain atlases are constructed from 2-month-old adult male mice. Furthermore, although both normal aging and AD neurodegeneration display sexually dimorphic features, the scientific community lacks the sexually differentiated rodent brain atlases necessary to study these attributes. By applying cutting edge technologies, we have developed for BRAIN Initiative connectomic and cell type mapping projects, we will (1) generate sexually dimorphic 3D aging and AD brain atlases with granular hippocampus (HPF) molecular domains, that can be used as standard atlas templates for all HPF work and (2) we will comprehensively characterize morphological dystrophies, as well as connectional and synaptic disruptions, in aging and AD. In Specific Aim 1, publicly available standard 3D HPF atlases of aging and AD brains will be created. Data will be generated in 2-, 9-, and 18-month-old wildtype (WT), 5xFAD (early AD onset), and MAPT(H1)*N279K (late AD onset) male and female mice. Fine HPF domain delineations will be facilitated by 3D volumetric images of cyto- and myeloarchitecture, while additional histopathological markers (Aβ plaques/tau tangles) and chemoarchitectural details (glutamate, GABA, PV, SST, Calb1) will be mapped to create comprehensive histopathological and chemoarchitectural HPF atlases. In Specific Aim 2, We will systematically apply a genetic MORF3 sparse labeling approach to label, reconstruct, and analyze cell type specific neuronal morphology of all HPF regions at the granular level of their domains in WT, Vglut1.MORF3/5xFAD, PV.MORF3/5xFAD, Vglut1.MORF3/MAPT(H1)*N279K, and PV.MORF3/MAPT(H1)*N279K mice across age and sex. Our whole brain 3D clearing, immunostaining, imaging, and 3D neuronal reconstruction pipeline will be applied. Given that an etiology of AD-related cognitive decline is selective HPF synaptic disruptions, with dorsal HPF nodes being some of the earliest affected in AD, in Specific Aim 3, will examine progressive connectional disruptions along amyloid and tau pathology progression. Male and female MORF3 and double transgenic mice, MORF3/5xFAD and MORF3/MAPT(H1)*N279K, at 2m, 9m, and 18m of age will be used to reveal potential connectivity changes across aging and AD. The same groups will be used to determine synaptic-level HPF disruptions with the application of Expansion Microscopy that will capture super-resolution images of synaptic connections. In Specific Aim 4, we will create a web-based data portal that enables visualization, comparison, and analysis of neural circuits and cell types in 3D aging and AD brains. Our team, with decades of experience in connectomics, brain atlasing, and online visualization, is sure to deliver standard HPF atlas templates for all neuroscience research and to determine sexually dimorphic anatomic regions vulnerable across age and AD progression.