Sorbs2 Is Required For Learning And Memory In Murine Excitatory Neurons

Grace Rocco; Henry Lin; Kailey Said; Ryan Boudreau; Jared McLendon

doi:10.1152/physiol.2025.40.S1.1740

Abstract only Sorbs2 is a cytoskeletal adaptor protein expressed in hippocampal neurons; however, its mechanistic role in these cells remains understudied. A genetic variant in the Sorbs2 promoter is linked to increased Sorbs2 expression and an 11-year delay in Alzheimer’s Disease (AD) onset, suggesting that increased Sorbs2 may have a protective role. Sorbs2 expression is decreased in AD brains of patients and mouse models. We have shown that cardiomyocyte loss of Sorbs2 destabilized microtubule (MT) structures, whereas its overexpression promotes MT stability. However, the specific role(s) of Sorbs2 in the regulation of neuronal MTs or the intersection of Sorbs2 and AD is unexplored. Here, we examine if Sorbs2 deletion destabilizes MTs in hippocampal neurons and impairs learning and memory behavior in mice. We generated whole body Sorbs2-Knockout (KO) mice and tested 6-month-old female littermates (n=16) using behavior tests. Postmortem brain samples showed loss of the neuron-specific Sorbs2 isoform (~150 kDa) and decreased Sorbs2 staining, particularly within the cerebral vasculature. MT stability assays suggest increased MT stability in Sorbs2-KO hippocampus tissues, but high variability limits interpretation. Behavioral tests (open field [OFT], spatial object recognition [SOR], and cued fear conditioning [CFC]) revealed no differences in OFT and CFC between WT and KO. However, KO mice spent significantly less time with the displaced object in SOR, suggesting impaired memory. Using Sorbs2-Flox mice (exon 12 flanked by loxP sites), we injected a pAAV.hSYN1.CRE virus to excise exon 12, leaving Sorbs2 nonfunctional. In mixed-sex cohorts (9F, 8M), saline-injected mice (n=9) were compared to CRE-injected (n=8). Behavioral tests revealed no differences in OFT or SOR, but CRE-injected mice showed reduced freezing in CFC (p=0.03), indicating potential memory impairment. Synaptosome protein extraction (SynPER), executed by a series of centrifugations, validates loss of neuronal Sorbs2 (~150 kDa) in KO mice. Preliminary data showed increased total neuronal expression in the Sorbs2-KO mouse, but synaptic enrichment (protein content of synapse versus cytosol) was higher in WT, though not statistically significant. I plan to increase the sample number to determine if increased statistical power would drive significance in enrichment. RNA-sequencing of hippocampal RNA (n=16) was used to study how Sorbs2 regulates other genes. This revealed downregulation of cytoskeleton-related genes in KO, consistent with Sorbs2’s role as a cytoskeletal adaptor. Ribosomal-based processes were upregulated, aligning with the RNA-binding function of the neuronal-specific exon. Our results suggest Sorbs2 may regulate MT stability in the brain and be involved in memory formation or retrieval. In the future, we will identify Sorbs2-expressing cell populations in the brain, investigate neuronal-specific Sorbs2 deletion, and assess the intersection between Sorbs2 and AD related phenotypes in mouse models of neurodegeneration. I plan to execute RNA in-situ hybridization experiments (using RNAscope) to study localization of Sorbs2. I will also carry out more MT assays to further study Sorbs2 regulation of MTs. This project is funded by the Alzheimer’s Association Research Fellowship (AARF) and the American Heart Association (AHA). Funding by the Alzheimer’s Association Research Fellowship (AARF) and the American Heart Association (AHA). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Sorbs2 Is Required For Learning And Memory In Murine Excitatory Neurons

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