Biology subjects

Schaler, A. W.

Publications and source records attributed to Schaler, A. W..

3 recordsLinked to original sources

bioRxiv2024

Dynamic changes in mitochondria support phenotypic flexibility of microglia

Microglial capacity to adapt to tissue needs is a hallmark feature of these cells. New studies show that mitochondria critically regulate the phenotypic adaptability of macrophages. To determine whether these organelles play similar roles in shaping microglial phenotype, we generated transgenic crosses to accurately visualize and manipulate microglial mitochondria. We find that brain-region differences in microglial attributes and responses to aging are accompanied by regional differences in mitochondrial mass and aging-associated mitochondrial remodeling. Microglial mitochondria are also altered within hours of LPS injections and microglial expression of inflammation-, trophic-, and phagocytosis-relevant genes is strongly correlated with expression levels of mitochondria-relevant genes. Finally, direct genetic manipulation of microglial mitochondria alters microglial morphology and leads to brain-region specific effects on microglial gene expression. Overall, this study advances our understanding of microglial mitochondria and supports the idea that mitochondria influence basal microglia phenotype and phenotypic remodeling that takes place over hours to months.

neuroscience↗

bioRxiv2020

GPCR-mediated clearance of tau in post-synaptic compartments attenuates tau pathology in vivo

Accumulation of pathological tau in synapses has been identified as an early pathogenic event in Alzheimers disease (AD) and correlates strongly with cognitive decline in patients with AD. Tau is a cytosolic, axonal protein. However, in the disease condition, tau accumulates in post-synaptic compartments and pre-synaptic terminals, either due to missorting within neurons, trans-synaptic transfer between neurons or due to failure of clearance systems in synapses. Using a sub-cellular fractionation assay, we show that progressive deposition of seed competent tau occurs predominantly in post-synaptic compartments in a tau transgenic mouse and in AD patient brain, making these neuronal structures particularly vulnerable to tau toxicity. Tau-mediated post-synaptic toxicity could be further exacerbated by impaired proteasome activity which we detected by measuring the levels of polyubiquitin chains that target proteins to proteasomal degradation. To combat the accumulation of tau and proteasome impairment at the subcellular level, we devised a therapeutic strategy of proteasome-mediated clearance of tau restricted to the post-synaptic compartment. Utilizing the pharmacology of GPCRs, we show that in vivo stimulation of the PAC1R receptor by its ligand can propagate intracellular PKA signaling leading to enhanced synaptic proteasome activity and reduced tau in the post-synaptic compartment. Over time, clearance of post-synaptic tau led to reduced tauopathy and cognitive decline in rTg4510 mice. Together, these results highlight a novel therapeutic strategy of targeting GPCRs that propagate cAMP/PKA signaling as a tool to activate proteolysis restricted to synapses to prevent the accumulation of tau in the early stages of AD.

neuroscience↗

bioRxiv2017

Estradiol and luteinizing hormone reverse memory loss in phencyclidine model of schizophrenia: Evidence for hippocampal GABA action

The cognitive symptoms of schizophrenia are poorly understood and difficult to treat. Estrogens may mitigate these symptoms via unknown mechanisms. To examine these mechanisms, we tested whether increasing estradiol (E) or decreasing luteinizing hormone (LH) could rescue declarative memory in a phencyclidine (PCP) model of schizophrenia. We then assessed whether changes in cortical or hippocampal GABA may underlie these effects. Female rats were ovariectomized and injected subchronically with PCP. To modulate E and LH, animals received hormone capsules or Antide injections. Short-term episodic memory was assessed using the novel object recognition task. Brain expression of GAD67 was analyzed via western blot, and parvalbumin-containing cells were counted using immunohistochemistry. Some rats received hippocampal infusions of a GABAA agonist, GABAA antagonist, or GAD inhibitor before behavioral testing. We found that PCP reduced hippocampal GAD67 and abolished object recognition. Antide restored hippocampal GAD67 and rescued recognition memory in PCP-treated animals. Estradiol reversed PCPs amnesic effect but failed to restore hippocampal GAD67. PCP did not cause significant differences in number of parvalbumin-expressing cells or cortical expression of GAD67. Hippocampal infusions of a GABAA agonist restored memory in PCP-treated rats. Blocking hippocampal GAD or GABAA receptors in ovx animals reproduced memory loss similar to PCP and inhibited estradiols memory rescue in PCP-treated animals. In summary, decreasing LH or increasing E can reverse memory loss in a PCP model of schizophrenia. Alterations in hippocampal GABA may contribute to both PCPs effects on declarative memory and the hormones ability to reverse them.

neuroscience↗