Biology subjects

Cannon, J. R.

Publications and source records attributed to Cannon, J. R..

4 recordsLinked to original sources

bioRxiv2025

γ-glutamyl-cysteine is a critical intermediate in glutathione-led amelioration of PFOS-neurotoxicity

Perfluorooctane sulfonate (PFOS) is one of the most prevalent PFAS. Earlier studies using Caenorhabditis elegans indicated that glutathione (GSH) ameliorates PFOS-induced neurodegeneration. This study investigates the GSH synthesis pathway to elucidate critical neuroprotective mechanisms. We assessed the effects of GSH precursors, cysteine, glutamic acid, and cysteine + glutamic acid, and of the intermediate {gamma}-glutamyl-cysteine ({gamma}-Glu-Cys), on PFOS neurotoxicity. While cysteine showed slight neuroprotection, other GSH precursors, glutamate, and cysteine + glutamate did not demonstrate beneficial effects. However, the crucial GSH synthesis intermediate, {gamma}-Glu-Cys, conferred neuroprotection comparable to GSH. Notably, no changes were observed in the gene or protein expression of GSH synthesis enzymes in C. elegans and SH-SY5Y cells, respectively. Further, testing of the alternative pathway for 5-oxoproline-mediated GSH synthesis revealed that it is not involved in {gamma}-glutamyl-cysteine-mediated neuroprotection. Paradoxically, 5-oxoproline supplementation was neurotoxic, plausibly due to glutamate toxicity. Further, we tested the effect of acute PFOS exposure on mitochondrial complexes I, II, III, and IV. We observed significant inhibition of enzyme activity in mitochondrial complexes II, III, and IV. Next, we tested whether GSH and {gamma}-Glu-Cys could rescue PFOS-induced enzyme inhibition. We found that while both GSH and {gamma}-Glu-Cys could rescue enzyme inhibition in complex III, the rescuing effect was altogether absent for complex IV. Overall, our findings confirmed that both GSH and {gamma}-Glu-Cys can rescue PFOS-induced neurodegeneration and mitochondrial enzyme affliction. This study effectively uncovers a novel mechanism that addresses existing knowledge gaps pertaining to the role of the GSH pathway in curtailing PFOS neurotoxicity. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/657248v3_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@1050eeborg.highwire.dtl.DTLVardef@11668e0org.highwire.dtl.DTLVardef@3f51ddorg.highwire.dtl.DTLVardef@1178865_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract {gamma}-glutamyl-cysteine is the critical intermediate in glutathione-modulated amelioration of PFOS-neurotoxicity Perfluorooctanesulfonate (PFOS) leads to dopaminergic cell loss in C. elegans. Glutathione (GSH) confers neuroprotection against PFOS neurotoxicity. Further investigation of the critical components involved in GSH biosynthesis identified that while precursors of GSH, Cysteine and glutamate fail to confer neuroprotection, only {gamma}-glutamyl-cysteine alleviates neuronal loss similar to GSH. C_FIG

neuroscience↗

bioRxiv2020

Dual Proteome-scale Networks Reveal Cell-specific Remodeling of the Human Interactome

Thousands of interactions assemble proteins into modules that impart spatial and functional organization to the cellular proteome. Through affinity-purification mass spectrometry, we have created two proteome-scale, cell-line-specific interaction networks. The first, BioPlex 3.0, results from affinity purification of 10,128 human proteins - half the proteome - in 293T cells and includes 118,162 interactions among 14,586 proteins; the second results from 5,522 immunoprecipitations in HCT116 cells. These networks model the interactome at unprecedented scale, encoding protein function, localization, and complex membership. Their comparison validates thousands of interactions and reveals extensive customization of each network. While shared interactions reside in core complexes and involve essential proteins, cell-specific interactions bridge conserved complexes, likely rewiring each cells interactome. Interactions are gained and lost in tandem among proteins of shared function as the proteome remodels to produce each cells phenotype. Viewable interactively online through BioPlexExplorer, these networks define principles of proteome organization and enable unknown protein characterization.

systems biology↗

bioRxiv2019

Advanced Glycation End-Products Suppress Mitochondrial Function and Proliferative Capacity of Achilles Tendon-Derived Fibroblasts

Debilitating cases of tendon pain and degeneration affect the majority of diabetic individuals. The high rate of tendon degeneration persists even when glucose levels are well controlled, suggesting that other mechanisms may drive tendon degeneration in diabetic patients. The purpose of this study was to investigate the impact of advanced glycation end-products on tendon fibroblasts to further our mechanistic understanding of the development and progression of diabetic tendinopathy. We proposed that advanced glycation end-products would induce limitations to mitochondrial function and proliferative capacity in tendon-derived fibroblasts, restricting their ability to maintain biosynthesis of tendon extracellular matrix. Using an in-vitro cell culture system, rat Achilles tendon fibroblasts were treated with glycolaldehyde-derived advanced glycation end-products (0, 50, 100, and 200g/ml) for 48 hours in normal glucose (5.5mM) and high glucose (25mM) conditions. We demonstrate that tendon fibroblasts treated with advanced glycation end-products display reduced ATP production, electron transport efficiency, and proliferative capacity. These impairments were coupled with alterations in mitochondrial DNA content and expression of genes associated with extracellular matrix remodeling, mitochondrial energy metabolism, and apoptosis. Our findings suggest that advanced glycation end-products disrupt tendon fibroblast homeostasis and may be involved in the development and progression of diabetic tendinopathy.

physiology↗

bioRxiv2019

Alpha-Synuclein is a Target of Fic-mediated Adenylylation/AMPylation: Implications for Parkinson’s Disease

During disease, cells experience various stresses that manifest as an accumulation of misfolded proteins and eventually lead to cell death. To combat this stress, cells activate a pathway called UPR (Unfolded Protein Response) that functions to maintain ER (endoplasmic reticulum) homeostasis and determines cell fate. We recently reported a hitherto unknown mechanism of regulating ER stress via a novel post-translational modification (PTM) called Fic-mediated Adenylylation/AMPylation. Specifically, we showed that the human Fic (filamentation induced by cAMP) protein, HYPE/FicD, catalyzes the addition of an AMP (adenosine monophosphate) to the ER chaperone, BiP, to alter the cells UPR-mediated response to misfolded proteins. Here, we report that we have now identified a second target for HYPE - alpha-Synuclein (Syn), a presynaptic protein involved in Parkinsons disease (PD). Aggregated Syn has been shown to induce ER stress and elicit neurotoxicity in PD models. We show that HYPE adenylylates Syn and reduces phenotypes associated with Syn aggregation in vitro, suggesting a possible mechanism by which cells cope with Syn toxicity.\n\nHIGHLIGHTSO_LIAggregated forms of the presynaptic protein Syn cause neurotoxicity and induce ER stress in cellular and animal models of Parkinsons disease.\nC_LIO_LIWe have identified Syn as a novel target for the human Fic protein, HYPE, a key regulator of ER homeostasis.\nC_LIO_LIHYPE adenylylates Syn and reduces the aggregation of recombinant Syn\nC_LIO_LIFic-mediated adenylylation/AMPylation is a possible mechanism by which cells cope with Syn toxicity.\nC_LI\n\nGraphic Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

biochemistry↗