PROJECT SUMMARY
BIN1, an adaptor protein encoded by the second most common susceptibility GWAS risk factor of late-onset AD,
regulates membrane dynamics in the context of endocytosis, membrane remodeling, and synaptic vesicle
release. Large-scale expression datasets have reported high-level BIN1 expression in microglia, and AD-
associated BIN1 SNPs are thought to alter BIN1 expression through a microglia-specific enhancer. However,
the precise functional role(s) of microglial BIN1 in regulating AD pathophysiology has not been investigated
systematically. Our central hypothesis is that microglial BIN1 plays an essential role in neuroinflammatory
signaling through which BIN1 influences AD pathophysiology. Our preliminary studies show that the loss of Bin1
expression in vitro (cultured microglia) and in vivo (microglia-specific cKO mice) profoundly impairs
proinflammatory gene expression and the upregulation of several disease-associated microglia (DAM) genes.
Our transcriptomic profiling identified BIN1 as a homeostatic microglial regulator with a non-redundant role in
activating proinflammatory response upstream of Apoe, Trem2, and Tyrobp, and upstream of PU.1 and IRF1.
BIN1 was predicted to regulate type 1 and 2 interferon responses in microglia in vitro and in vivo. Collectively,
these findings offer important insights into microglial BIN1 function, demonstrating its significance in brain
inflammatory response. The overall objective of this proposal is to explore BIN1’s role in microglia further,
especially in the context of AD pathogenesis, and gain molecular insights. The goal of Aim 1 is to generate
5XFAD:Bin1 cKO mice to elucidate microglial BIN1 function in the modulation of cerebral amyloid burden and
amyloid-associated pathophysiology. We will conduct detailed biochemical, molecular, and neuropathological
characterization and perform transcriptomics profiling of neuroinflammation and DAM transition to understand
BIN1’s role in microglial response to amyloid pathology. Aim 2 studies seek to generate PS19:Bin1 cKO mice to
elucidate the involvement of microglial BIN1 function in tau pathophysiology and pathology propagation using
detailed neuropathology and comprehensive biochemical, proteomics, and molecular analyses. Aim 3 studies
will investigate the mechanistic role of BIN1 as a crucial regulator of early inflammatory signaling events in
microglia. We will use unbiased and hypothesis-driven approaches to define the microglial BIN1 interactome and
elucidate how BIN1 and its binding partners are reorganized in a context-dependent manner to facilitate immune
signaling via key microglial receptors. This timely and unique proposal is highly innovative. Our strategy to use
microglia-specific inducible Bin1 cKO mice represents the most direct in vivo approach to rigorously investigate
how microglial BIN1 regulates AD pathophysiology and gain insights using comprehensive transcriptomics,
proteomics, and interactome characterization. We believe that the successful completion of the proposed
research will fill significant gaps in our understanding of BIN1 as a risk factor for LOAD and guide future functional
characterizations of molecular pathways and pathogenic mechanisms regulated by this major LOAD risk gene.