Biology subjects

Gebis, K. K.

Publications and source records attributed to Gebis, K. K..

3 recordsLinked to original sources

bioRxiv2025

Ubiquitin Proteasome System Components, RAD23A and USP13, Modulate TDP-43 Solubility and Neuronal Toxicity

At autopsy, >95% of ALS cases display a redistribution of the essential RNA binding protein TDP-43 from the nucleus into cytoplasmic aggregates. The mislocalization and aggregation of TDP-43 is believed to be a key pathological driver in ALS. Due to its vital role in basic cellular mechanisms, direct depletion of TDP-43 is unlikely to lead to a promising therapy. Therefore, we have explored the utility of identifying modifier genes that modify its mislocalization or aggregation. We have previously shown that loss of rad-23 improves locomotor deficits in TDP-43 C. elegans models of disease and increases the degradation rate of TDP-43 in cellular models. To understand the mechanism through which these protective effects occur, we generated an inducible mutant TDP-43 HEK293 cell line. We find that knockdown of RAD23A reduces insoluble TDP-43 levels in this model and primary rat cortical neurons expressing human TDP-43A315T. Utilizing a discovery-based proteomics approach, we then explored how loss of RAD23A remodels the proteome. Through this proteomic screen, we identified USP13, a deubiquitinase, as a new potent modifier of TDP-43 induced aggregation and cytotoxicity. We find that knockdown of USP13 reduces the abundance of sarkosyl insoluble mTDP-43 in both our HEK293 model and primary rat neurons, reduces cell death in primary rat motor neurons, and improves locomotor deficits in C. elegans ALS models. Significance StatementAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease (NDD) with no effective therapies. The mislocalization and aggregation of TAR DNA binding protein 43 (TDP-43) is a key pathological marker of ALS and other NDDs. Due to its vital functions, targeted therapeutic reduction of TDP-43 could be problematic. Here, we have explored the utility of targeting modifier genes. We find that knockdown of two members of the ubiquitin proteasome system, RAD23A and USP13, enhance TDP-43 solubility and decrease TDP-43 induced neurotoxicity.

neuroscience↗

bioRxiv2024

Reduction of RAD23A extends lifespan and mitigates pathology in TDP-43 mice

Protein misfolding and aggregation are cardinal features of neurodegenerative disease (NDD) and they contribute to pathophysiology by both loss-of-function (LOF) and gain-of-function (GOF) mechanisms. This is well exemplified by TDP-43 which aggregates and mislocalizes in several NDDs. The depletion of nuclear TDP-43 leads to reduction in its normal function in RNA metabolism and the cytoplasmic accumulation of TDP-43 leads to aberrant protein homeostasis. A modifier screen found that loss of rad23 suppressed TDP-43 pathology in invertebrate and tissue culture models. Here we show in a mouse model of TDP-43 pathology that genetic or antisense oligonucleotide (ASO)-mediated reduction in rad23a confers benefits on survival and behavior, histological hallmarks of disease and reduction of mislocalized and aggregated TDP-43. This results in improved function of the ubiquitin-proteasome system (UPS) and correction of transcriptomic alterations evoked by pathologic TDP-43. RAD23A-dependent remodeling of the insoluble proteome appears to be a key event driving pathology in this model. As TDP-43 pathology is prevalent in both familial and sporadic NDD, targeting RAD23A may have therapeutic potential.

neuroscience↗

bioRxiv2024

Keratinocyte-derived exosomes in painful diabetic neuropathy

Painful diabetic neuropathy (PDN) is a challenging complication of diabetes with patients experiencing a painful and burning sensation in their extremities. Existing treatments provide limited relief without addressing the underlying mechanisms of the disease. PDN involves the gradual degeneration of nerve fibers in the skin. Keratinocytes, the most abundant epidermal cell type, are closely positioned to cutaneous nerve terminals, suggesting the possibility of bi-directional communication. Exosomes are small extracellular vesicles released from many cell types that mediate cell to cell communication. The role of keratinocyte-derived exosomes (KDEs) in influencing signaling between the skin and cutaneous nerve terminals and their contribution to the genesis of PDN has not been explored. In this study, we characterized KDEs in a well-established high-fat diet (HFD) mouse model of PDN using primary adult mouse keratinocyte cultures. We obtained highly enriched KDEs through size exclusion chromatography and then analyzed their molecular cargo using proteomic analysis and small RNA sequencing. We found significant differences in the protein and microRNA content of HFD KDEs compared to KDEs obtained from control mice on a regular diet (RD), including pathways involved in axon guidance and synaptic transmission. Additionally, using an in vivo conditional extracellular vesicle (EV) reporter mouse model, we demonstrated that epidermal-originating GFP-tagged KDEs are retrogradely trafficked into the DRG neuron cell body. Overall, our study presents a potential novel mode of communication between keratinocytes and DRG neurons in the skin, revealing a possible role for KDEs in contributing to the axonal degeneration that underlies neuropathic pain in PDN. Moreover, this study presents potential therapeutic targets in the skin for developing more effective, disease-modifying, and better-tolerated topical interventions for patients suffering from PDN, one of the most common and untreatable peripheral neuropathies.

neuroscience↗