W35 - Microglial Piezo1 is Crucial for Regulating Toxic Lipid Uptake and Mitochondrial Function

Saturday, October 11, 2025

10:00 AM - 11:00 AM PDT

Location: Exhibit Hall F, G & H

Presenting Author(s)

Allison Lee

Student
University of California Irvine, United States

Co-Author(s)

TK

Tamara Kyaw

Student
University of California Irvine, United States
OY

Olivia Yoshii

Student
University of California Irvine, United States
Daanish Kulkarni

Graduate Student Researcher
UC Irvine
Irvine, California, United States
Thuy-Khanh Tran-Dao

Graduate Student Researcher
UC Irvine
Irvine, California, United States

Primary Investigator(s)

Wendy F. Liu, PhD

Professor
University of California, Irvine
Irvine, California, United States

Introduction: : Alzheimer’s disease (AD) is one of the most common forms of dementia, characterized by the aggregation of amyloid plaques, followed by neuroinflammation, the formation of neurofibrillary tangles from hyperphosphorylated Tau (pTau), and ultimately synaptic/neuronal loss resulting in cognitive impairment. Microglia, the primary immune cells of the brain, are the main drivers of neuropathology. Their metabolic state plays a significant role in regulating immune function and maintaining brain homeostasis, with diminished metabolic capacity being a key characteristic of dysfunctional microglia. In addition to this metabolic switch, microglia are known to tightly associate with amyloid plaques, which are uniquely stiff compared to the surrounding brain parenchyma. Piezo1, a mechanosensitive ion channel, detects this change in stiffness and, in recent years, has been found to play a crucial role in microglial function during AD by facilitating amyloid uptake and cell migration. Although the role of Piezo1 in microglia-amyloid interactions has been well studied, the role of Piezo1 in microglial metabolism is not well understood. The objective of our study is to investigate the potential role of Piezo1 in alterations to two key metabolic parameters in microglia in the context of AD – lipid uptake and mitochondria morphology/function.

Materials and

Methods: : BV2 mouse microglia cells were seeded and either unprimed or primed with lipopolysaccharide (LPS) to mimic aged inflammatory microglia. To simulate tissue stiffness in the AD brain, cells were seeded onto either soft 1kPa or stiff 280 kPa polyacrylamide hydrogels to mimic healthy vs plaque-associated brain tissue. For pharmacological stimulation, the cells were treated with Yoda1, a Piezo1 agonist. To evaluate oxidized lipid uptake, cells were incubated with oxidized low-density lipoprotein (oxLDL) and analyzed by confocal microscopy and flow cytometry. In our studies, we utilized oxLDL due to oxidative stress in the AD brain, leading to toxic oxidation of lipid species. Protein levels of lipid uptake receptors CD36 and LOX-1 were measured through western blot analysis. To evaluate mitochondrial function, the Seahorse XF96 analyzer was used to perform the MitoStress Test. For this test, oxygen consumption rate and extracellular acidification rate were measured, which correspond to mitochondrial respiration or glycolytic activity, respectively. This assay involves the sequential injection of Yoda1, oligomycin A (ATPase inhibitor), BAM15 (mitochondria energy uncoupler), and a combination of Antimycin A/Rotenone (electron transport chain inhibitors) to allow us to determine additional metabolic properties such as ATP production and spare respiratory capacity. To evaluate mitochondrial membrane potential - a measure of functional mitochondria - cells were stained with TMRM and analyzed through flow cytometry and confocal microscopy. Lipid peroxidation was measured using cells stained with BODIPY-C11 dye and flow cytometry. In all studies, we used either wildtype cells or cells with a Piezo1 genetic knockdown (~60%).

Results, Conclusions, and Discussions:: Increasing concentrations of Yoda1 led to a significant decrease in oxLDL uptake, which was also observed with cells on the stiff 280kPa hydrogels (Fig. 1A-C). In turn, we found that Piezo1 activation reduces the expression of both CD36 and LOX-1, key receptors involved in oxLDL uptake (Fig. 1D). Interestingly, oxLDL uptake in cells with Piezo1 genetically knocked down remained unaffected regardless of stiffness or Yoda1 treatment. We also found that lipid peroxidation decreases with Yoda1 treatment (Fig. 2). Decreased Piezo1 expression also led to diminished mitochondrial activity and decreased overall metabolic activity with both decreased oxygen consumption and glycolysis (Fig. 3A-C).

Our findings demonstrate that Piezo1 is instrumental in regulating lipid uptake and mitochondrial function in microglia. Piezo1 activation caused by stiff hydrogels and Yoda1 lowers the uptake of oxidized lipids and cellular peroxidation, which may indicate a protective role from oxidative stress and cell death due to these toxic lipid species. Additionally, we show that normal Piezo1 expression directly prevents metabolic and mitochondrial dysfunction, which has been previously shown to drive the severity of AD pathology. Our future studies will assess mitochondrial morphology, which correlates with preferred metabolic pathways. We will also assess bioenergetics in cerebral organoids containing iPSC-derived microglia with different Piezo1 genetic constructs, and humanized mice transplanted with these microglia. This will allow us to elucidate the role of Piezo1 on human microglia in physiologically relevant AD models.

Acknowledgements and/or References (Optional): : Funding from an NIH/NIA R21 AG069067 grant, NIH/NINDS T32 NS121727-01 grant, and support from NIH award S10OD0250264 for the Olympus FV3000 Confocal Microscope.