Biology subjects

Rekowski, M. J.

Publications and source records attributed to Rekowski, M. J..

4 recordsLinked to original sources

bioRxiv2026

Metformin Redirects Autophagy from Bulk Turnover to Mitochondrial Clearance

Metformin is the most widely prescribed antidiabetic drug and an active candidate for repurposing in oncology. How it engages autophagy - a pathway central to both its metabolic and its anti-tumor effects - has remained unresolved, with reports of induction, suppression, and no effect. Here we show that metformin reroutes rather than induces or inhibits autophagy in human cancer cells: at therapeutic concentrations, it suppresses bulk cytosolic turnover by selectively blocking WIPI2-mediated phagophore tethering, while the ULK1 initiation complex relocates toward mitochondria and engages selective mitochondrial clearance. We trace this redirection to mitochondrial complex I inhibition, registered as a shift in the NAD+/NADH ratio before any change in the adenylate pool, and to a non-canonical reprogramming of the ULK1 complex that operates independently of mTORC1 and of the proposed PEN2-lysosomal route. AMPK is engaged in a subunit-specific manner that restrains ATG13 at initiation and enables WIPI2 displacement at maturation. The ULK1 complex is therefore the node at which metformin sets autophagic substrate selection, with direct implications for combination therapy in diabetes and cancer.

cell biology↗

bioRxiv2026

Dietary Oxysterols Reprogram Hepatic Lipid Metabolism and Reshape the Gut Metabolome-Microbiome Interface

Dietary oxysterols are biologically active cholesterol oxidation products ubiquitous in Western diets, yet their systemic effects on host metabolism and the gut microbiome remain largely unexplored. Here, we employed an integrated multi-omics approach - shotgun metagenomics, quantitative proteomics, untargeted metabolomics, and bulk RNA-seq - to characterize the impact of DOxS exposure on the gut-liver axis in rats fed a Western diet (WD vs. WD-DOxS). Hepatic proteomics revealed near-complete suppression of the mevalonate/cholesterol biosynthesis pathway, particularly in males, while de novo lipogenesis enzymes (Scd1, Fasn, Plin2) were paradoxically upregulated, consistent with dual oxysterol signaling through SREBP inhibition and LXR activation. Bile acid synthesis was concurrently suppressed, confirmed by metabolomics. Strikingly, RNA-seq across liver, heart, and brain detected virtually no differentially expressed genes, establishing that DOxS act predominantly through post-transcriptional mechanisms. In the gut, DOxS increased microbial -diversity while depleting Limosilactobacillus reuteri, with concomitant loss of the barrier-protective metabolite 3-indoleacrylic acid. Tissue-specific responses were widespread, with liver and colon frequently mounting opposing metabolic and immune responses to the same dietary challenge. Cross-omics integration revealed convergent microbiome-metabolite axes connecting microbial remodeling to both hepatic lipid reprogramming and colonic barrier disruption. These findings reposition dietary oxysterols from food-quality markers to active modulators of the gut-liver axis, with implications for metabolic disease and intestinal barrier integrity.

biochemistry↗

bioRxiv2025

Integrated multi-omic analysis reveals novel subtype-specific regulatory interactions in pediatric B-cell acute lymphoblastic leukemia

Molecular subtyping of pediatric B-cell acute lymphoblastic leukemia (B-ALL) has improved patient outcomes through stratification and selection of targeted therapies. Despite extensive genomic and transcriptomic profiling of this cancer, few studies to date have characterized the proteomic landscape, although proteins are the direct targets of many therapeutic agents. In this study, we demonstrate the utility of multi-omic integration of global transcriptomic, proteomic, and phosphoproteomic profiles of samples from patients diagnosed with either of two B-ALL subtypes - Ph- like (BCR::ABL1-like) and ETV6::RUNX1. Through individual and multi-omic analysis, we recapitulate known transcriptomic findings and identify novel subtype-specific proteomic and phosphoproteomic biomarkers. Our findings suggest a previously undescribed role for calcium-dependent signaling processes in Ph-like B-ALL, which has the potential to serve as a novel avenue for targeted treatments. By integrating multiple omics modalities, we identify not only features of interest but also begin to unravel the regulatory interactions driving subtype-specific mechanisms of leukemogenesis. This integrated analytic approach paves the way for enhanced precision medicine for precise subtyping and treatment selection for pediatric leukemia patients. Mass spectrometry data generated in this study have been deposited in MassIVE under accession MSV000097955.

cancer biology↗

bioRxiv2024

Differential Remodeling of the BRCA1 Interactome by a Unique Minimal Clinical Truncation Mutation

BRCA1, a critical tumor suppressor gene, plays an essential role in maintaining genomic stability through its involvement in DNA double-strand break repair, particularly via homologous recombination. Loss or impairment of BRCA1 function disrupts this repair pathway, resulting in genomic instability and significantly increased susceptibility to breast and ovarian cancers. To elucidate the molecular mechanisms by which BRCA1 mutations contribute to tumorigenesis, we employed quantitative mass spectrometry-based proximity labeling and affinity purification to identify cancer-specific protein-protein interactions (PPIs). Our integrated omics and visualization analysis of interactors revealed that the BRCA1-Y1853ter mutant, through its interaction with BARD1, perturbs the interactome and impacts cellular processes within the cytoplasm and nucleoplasm. Structural data further corroborated these findings, showing enhanced binding between the mutant BRCA1 and specific interactors, suggesting an altered functional profile. Together, these observations raise the hypothesis that the BRCA1-Y1853ter mutant may exhibit gain-of-function characteristics, providing new insights into the molecular and cellular effects of mutations in the BRCA1 C-Terminal (BRCT) domain and their implications for the pathogenesis of breast and ovarian cancers.

cancer biology↗