Biology subjects

Ezerina, D.

Publications and source records attributed to Ezerina, D..

5 recordsLinked to original sources

bioRxiv2026

PTPRF is a stress responsive cytoskeletal checkpoint that coordinates metabolic adaptation in hepatocytes and β cells

Cytoskeletal remodeling is essential for adaptation to nutrient availability, yet how cells coordinate actin dynamics with glucose homeostasis in metabolic organs remains unclear. Here, we identify a pathway linking metabolic stress to actin reorganization in hepatocytes and pancreatic {beta} cells. This mechanism involves transcriptional repression of the receptor protein tyrosine phosphatase PTPRF by spliced XBP1, a key unfolded protein response factor. In hepatocytes, PTPRF loss under dietary stress enhances insulin signaling, increases mitochondrial respiration and reduces steatosis. Proteomic analyses show that PTPRF interacts with regulators of actin polymerization and cell junctions, and its deletion promotes actin filament organization, shifting metabolism toward oxidative pathways. In {beta} cells, PTPRF deficiency similarly enhances actin polymerization and augments glucose-stimulated insulin secretion in obesity. Collectively, these findings place PTPRF as a nutrient-responsive regulator of cytoskeletal remodeling that coordinates hepatic metabolism and {beta}-cell function, highlighting its potential as a therapeutic target for improving systemic glucose control.

physiology↗

bioRxiv2026

Challenges in reconstituting the peroxiredoxin 2:STAT3 transient redox-relay complex in vitro

Peroxiredoxin 2 (Prdx2) mediates redox signaling by transferring oxidative equivalents to target proteins such as STAT3, a redox-sensitive transcription factor implicated in inflammation and cancer. Although this interaction has been demonstrated in cells, reconstituting the Prdx2:STAT3 complex in vitro remains challenging due to its transient and redox-dependent nature. Here we test various conditions to stabilize the complex between taggless Prdx2 and the core fragment of STAT3 (CF-STAT3), including oxidants, detergents, the facilitator Annexin A2, anaerobic environments, and CovalX crosslinking. Complex formation was assessed via mass photometry, analytical size-exclusion chromatography (SEC), SEC-MALS, and electron microscopy (EM). No stable complex was observed under standard conditions. Anaerobic environments briefly stabilized the interaction, but cryo-EM could not resolve the structure. CovalX crosslinking yielded short-lived but homogeneous complexes. We found that Prdx2 is highly susceptible to hyperoxidation at its peroxidatic cysteine, particularly in the presence of DTT or excess H2O2, resulting in loss of function. Maintaining non-reducing conditions during purification preserved Prdx2 in an oxidation-competent state, promoting formation of the disulfide bond between the peroxidatic and resolving cysteines and thereby enabling reproducible detection of a weak complex with CF-STAT3. Our findings establish a framework for studying redox-relay protein complexes in vitro and highlight the importance of oxidation state management during protein handling.

molecular biology↗

bioRxiv2025

Pervanadate-induced oxidation relieves autoinhibition of SRC protein tyrosine kinase

Dynamic regulation of protein tyrosine phosphorylation (pTyr) by phosphatases (PTPs) and kinases enables cells to sense and respond to environmental changes. The widely used chemical probe Pervanadate (PV) induces accumulation of high levels of pTyr in cells, an effect primarily attributed to its properties as a PTP inhibitor. This led to the assertion that PTPs are the master gatekeeper of intracellular pTyr homeostasis. Here, we use diverse approaches to reveal that PV disrupts cellular redox homeostasis and directly activates SRC family tyrosine kinases via oxidation of specific cysteine residues. Using mass spectrometry and biophysical approaches, we show that oxidation activates SRC by disrupting autoinhibition and altering phosphopeptide binding by its SH2 domain. We further establish that redox-sensitive cysteine residues are essential for SRC to promote cellular overgrowth. Our findings call for a re-evaluation of PV-based experiments and provide compelling evidence that oxidation is a crucial mechanism in controlling the oncogenic properties of SRC.

molecular biology↗

bioRxiv2024

Thermal Proteome Profiling reveals rapid proteomic responses to redox changes in specific cellular compartments

Hydrogen peroxide (H2O2) functions as a secondary messenger in cellular redox signaling, acting mainly via oxidation of protein thiols. Its spatially and temporally regulated activity within cells is essential for maintaining proper redox balance, and disruptions in these patterns can lead to oxidative stress and various related pathologies. Redox proteomics, which examines the impact of H2O2 at the proteome level, typically focuses only on thiol oxidation, overlooking broader proteomic alterations and the significance of subcellular localization in these redox processes. In this study, we address these open questions by combining chemogenetics with Thermal Proteome Profiling (TPP) to map global proteome response to compartmentalized H2O2 production. We identified hundreds of proteins with altered thermostability and/or abundance upon localized H2O2 generation in the cytosol, nucleus, and the ER lumen, highlighting their roles in cellular responses to localized H2O2. We identified proteins such as MAP2K1, PARK7, TRAP1, and UBA2 to be highly sensitive to localized H2O2 production. Furthermore, we validated their altered thermostability and found that these changes are controlled via dysregulated protein-protein interactions. This study provides a valuable resource for researchers exploring redox-mediated signal transduction and offers novel insights that could be harnessed in treating oxidative stress-induced pathologies.

systems biology↗

bioRxiv2023

Protein tyrosine phosphatase receptor kappa regulates glycolysis and de novo lipogenesis to promote hepatocyte metabolic reprogramming in obesity

Fat accumulation, de novo lipogenesis, and glycolysis are key drivers of hepatocyte reprogramming and the consequent metabolic dysfunction-associated steatotic liver disease (MASLD). Here we report that obesity leads to dysregulated expression of hepatic protein-tyrosine phosphatases (PTPs). PTPRK was found to be increased in steatotic hepatocytes in both humans and mice, and positively correlated with PPAR{gamma}-induced lipogenic signalling. High-fat-fed PTPRK knockout mice displayed reduced weight gain and hepatic fat accumulation. Phosphoproteomic analysis in primary hepatocytes and hepatic metabolomics identified fructose-1,6-bisphosphatase 1 and glycolysis as PTPRK targets in metabolic reprogramming. Silencing PTPRK in hepatoma cell lines resulted in reduced colony-forming ability and PTPRK knockout mice developed smaller tumours after diethylnitrosamine-induced hepatocarcinogenesis. Our study defines a novel role for PTPRK in regulating hepatic glycolysis, lipid metabolism, and tumour development. PTPRK inhibition may provide therapeutic possibilities in obesity-associated liver diseases. HighlightsO_LIHepatic receptor-type PTPs are increased in MASLD C_LIO_LIPTPRK is expressed in hepatocytes and upregulated in obesity C_LIO_LIPTPRK deficiency reduces body fat mass and liver steatosis in diet-induced obesity C_LIO_LIPTPRK regulates hepatic glycolysis and lipogenesis, promoting tumorigenesis C_LI

cancer biology↗