Biology subjects

Staats, K. A.

Publications and source records attributed to Staats, K. A..

3 recordsLinked to original sources

bioRxiv2024

An ALS Therapeutic Assembly Modulator Target in Peripheral Blood Mononuclear Cells: Implications for ALS Pathophysiology, Therapeutics, and Diagnostics

Assembly modulators are a new class of allosteric site-targeted therapeutic small molecules, some of which are effective at restoring nuclear localization of TDP-43 in ALS cellular models, and which display efficacy in a variety of ALS animal models. These compounds have been shown to bind selectively to a small subset of protein disulfide isomerase (PDI), a protein implicated in ALS pathophysiology. The targeted subset of PDI is found within a novel, transient and energy-dependent multi-protein complex that includes other important members of the ALS interactome, such as TDP-43, RanGTPase, and selective autophagy receptor p62/SQSTM1. We demonstrate here that a similar multi-protein complex drug target is present in PBMCs as isolated by energy-dependent drug resin affinity chromatography (eDRAC) and characterized by mass spectrometry and by Western blot (WB). Signature alterations in the composition of the multi-protein complex in PBMCs from ALS patients compared to PBMCs from healthy individuals were identified by WB of eDRAC bound proteins, thereby extending earlier literature suggesting PBMC dysfunction in ALS. Changes in the PBMC drug target in ALS patients compared to healthy individuals include diminished p62/SQSTM1 and appearance of a 17kDa post-translationally modified form of RanGTPase. These changes are not readily apparent from analysis of whole cell extracts, as the individual protein components within the drug target multi-protein complex comprise only small percentages of the total of those component proteins in the extract. Furthermore, whole blood from ALS patients shows a distinctive degradation of total RanGTPase not observed in blood from healthy individuals. This degradation appears to be rescued by treatment of whole blood from ALS patients for 72 hrs with ALS-active assembly modulator small molecules. Our findings are consistent with the hypothesis that ALS is fundamentally a disorder of homeostasis that can be detected early, prior to disability, in blood by the methods described, and restored to the healthy state by assembly modulator drug treatment.

physiology↗

bioRxiv2023

Protein Assembly Modulation: A New Approach to ALS Therapeutics

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease with a complex, multifactorial pathophysiology, most commonly manifest as loss of motor neurons. We introduce a new mechanism of ALS pathogenesis via a novel drug-like small molecule series that targets protein disulfide isomerase (PDI) within a previously unappreciated transient and energy-dependent multi-protein complex. This novel drug was found to have activity in cellular models for both familial and sporadic ALS, as well as in transgenic worms, flies, and mice bearing a diversity of human genes with ALS-associated mutations. These compounds were initially identified as modulators of human immunodeficiency virus (HIV) capsid assembly in cell-free protein synthesis and assembly (CFPSA) systems, with demonstrated antiviral activity in cell culture. Their advancement as ALS-therapeutics, and the subsequent separation of activity against HIV and ALS in chemical subseries through structure-activity-relationship optimization, may provide insights into the molecular mechanisms governing pathophysiology of disordered homeostasis relevant to ALS.

neuroscience↗

bioRxiv2019

Small molecule inhibition of PIKFYVE kinase rescues gain- and loss-of-function C9ORF72 ALS/FTD disease processes in vivo

The most common known cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is a hexanucleotide repeat expansion (HRE) in C9ORF72 that contributes to neurodegeneration by both loss-of-function (decreased C9ORF72 protein levels) and gain-of-function (e.g. dipeptide repeat protein production) mechanisms. Although therapeutics targeting the gain-of-function mechanisms are in clinical development, it is unclear if these will be efficacious given the contribution of C9ORF72 loss-of-function processes to neurodegeneration. Moreover, there is a lack of therapeutic strategies for C9ORF72 ALS/FTD with demonstrated efficacy in vivo. Here, we show that small molecule inhibition of PIKFYVE kinase rescues both loss- and gain-of-function C9ORF72 disease mechanisms in vivo. We find that the reduction of C9ORF72 in mouse motor neurons leads to a decrease in early endosomes. In contrast, treatment with the PIKFYVE inhibitor apilimod increases the number of endosomes and lysosomes. We show that reduced C9ORF72 levels increases glutamate receptor levels in hippocampal neurons in mice, and that apilimod treatment rescues this excitotoxicity-related phenotype in vivo. Finally, we show that apilimod also alleviates the gain-of-function pathology induced by the C9ORF72 HRE by decreasing levels of dipeptide repeat proteins derived from both sense and antisense C9ORF72 transcripts in hippocampal neurons in vivo. Our data demonstrate the neuroprotective effect of PIKFYVE kinase inhibition in both gain- and loss-of-function murine models of C9ORF72 ALS/FTD.

neuroscience↗