Biology subjects

Schisler, J.

Publications and source records attributed to Schisler, J..

3 recordsLinked to original sources

bioRxiv2025

Synergistic MAPT mutations as a platform to uncover modifiers of tau pathogenesis

The natively unfolded tau (MAPT) protein is extremely soluble, which poses challenges when modeling neurofibrillary tangle (NFT) pathology in Alzheimers disease (AD). To overcome this hurdle, we combined P301L and S320F mutations (PL-SF) to generate a rapid and reliable tau pathology platform to expedite the discovery of factors that modify tau aggregation. Using this model, we evaluated heat-shock proteins (Hsp), which have been linked to tau pathology, but whose role in AD remains enigmatic and controversial. In primary neurons, expression of Hsp70, but not Hsc70 or Hsp90, exacerbated tau aggregation. Conversely, lowering Hsp70 or employing a chaperone-deficient tau mutant (PL-SF-4{Delta}) reduced tau phosphorylation and abrogated tau aggregation, highlighting Hsp70 as a key driver of tau aggregation. Hsp70 foci clustered within and surrounding neuritic plaques and NFTs in post-mortem AD brain. Functionally, mature aggregate-bearing neurons showed deficits in neuronal firing and network communication, which were restored by chaperone-binding deficient tau variants that abrogated tau pathology. This study provides a powerful cell-intrinsic model for accelerated tau aggregation, which can be harnessed to identify potent regulators of tau aggregation as promising therapeutic targets.

neuroscience↗

bioRxiv2021

Systemic Tissue and Cellular Disruption from SARS-CoV-2 Infection revealed in COVID-19 Autopsies and Spatial Omics Tissue Maps

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) virus has infected over 115 million people and caused over 2.5 million deaths worldwide. Yet, the molecular mechanisms underlying the clinical manifestations of COVID-19, as well as what distinguishes them from common seasonal influenza virus and other lung injury states such as Acute Respiratory Distress Syndrome (ARDS), remains poorly understood. To address these challenges, we combined transcriptional profiling of 646 clinical nasopharyngeal swabs and 39 patient autopsy tissues, matched with spatial protein and expression profiling (GeoMx) across 357 tissue sections. These results define both body-wide and tissue-specific (heart, liver, lung, kidney, and lymph nodes) damage wrought by the SARS-CoV-2 infection, evident as a function of varying viral load (high vs. low) during the course of infection and specific, transcriptional dysregulation in splicing isoforms, T cell receptor expression, and cellular expression states. In particular, cardiac and lung tissues revealed the largest degree of splicing isoform switching and cell expression state loss. Overall, these findings reveal a systemic disruption of cellular and transcriptional pathways from COVID-19 across all tissues, which can inform subsequent studies to combat the mortality of COVID-19, as well to better understand the molecular dynamics of lethal SARS-CoV-2 infection and other viruses.

microbiology↗

bioRxiv2018

Disrupted structure and aberrant function of CHIP mediates the loss of motor and cognitive function in preclinical models of cerebellar CHIPopathy

CHIP (carboxyl terminus of heat shock 70-interacting protein) has long been recognized as an active member of the cellular protein quality control system given the ability of CHIP to function as both a co-chaperone and ubiquitin ligase. Mutations in CHIP are the driver of spinocerebellar autosomal recessive 16 (SCAR16), or cerebellar CHIPopathy, as we initially discovered this disease was caused by a loss of CHIP ubiquitin ligase function. The initial mutation describing SCAR16 was a missense mutation in the ubiquitin ligase domain of CHIP (p.T246M). Using multiple biophysical and cellular approaches, we demonstrate that T246M mutation results in structural disorganization and misfolding of the CHIP U-box domain, promoting oligomerization, and increased proteasome-dependent turnover. CHIP-T246M has no ligase activity, but maintains interactions with chaperones and alters the co-chaperone function of CHIP. To establish preclinical models of SCAR16, we engineered T246M at the endogenous locus in both mice and rats. Animals homozygous for T246M had both cognitive and motor cerebellar dysfunction distinct from those observed in the CHIP null animal model, as well as deficits in learning and memory, reflective of the cognitive deficits reported in SCAR16 patients. We conclude that the T246M mutation is not equivalent to the total loss of CHIP, supporting the concept that disease-causing CHIP mutations have different biophysical and functional repercussions on CHIP function that may directly correlate to the spectrum of clinical phenotypes observed in SCAR16 patients. Our findings both further expand our basic understanding of CHIP biology and provide meaningful mechanistic insight underlying the molecular drivers of SCAR16 disease pathology, which may be used to inform the development of novel therapeutics for this devastating disease.

animal behavior and cognition↗