Biology subjects

Faccioli, L. A. P.

Publications and source records attributed to Faccioli, L. A. P..

4 recordsLinked to original sources

bioRxiv2026

YY1 phosphorylation links non-apoptotic caspase-8 signaling to MASH fibrosis

Background & Aims: Metabolic dysfunction-associated steatohepatitis (MASH) is a leading cause of chronic liver disease, and liver fibrosis is the principal determinant of disease progression and clinical outcome. We recently showed that non-apoptotic caspase-8 in hepatocytes is upregulated in MASH and leads to the induction and secretion of meteorin, which promotes hepatic stellate cell (HSC) activation and liver fibrosis. We address here the major mechanistic question arising from this study, namely how non-apoptotic caspase-8 induces pro-fibrotic meteorin in hepatocytes in MASH. Methods: Mechanistic studies were performed using AML12 hepatocytes; primary mouse and human hepatocytes; and diet-induced mouse models of MASH with hepatocyte-specific caspase-8 deletion. YY1 post-translational modifications were identified by LC-MS/MS and investigated using phosphorylation-defective and phosphomimetic YY1 mutants. Genetic and biochemical approaches were used to interrogate the caspase-8 DED-SRC-GSK3b; pathway, and its relevance was assessed in human MASH liver specimens. Results: In vitro mechanistic studies showed that the amino-terminal death effector domain (DED) of caspase-8 activated a SRC-GSK3b signaling cascade that promoted phosphorylation of YY1 at Ser247, resulting in YY1 nuclear localization and Metrn induction. Disruption of the conserved DED RXDLL motif impaired SRC activation, YY1 phosphorylation, and Metrn expression. Hepatocyte YY1 overexpression increased Metrn expression and fibrosis in wild-type MASH mice but not in hepatocyte-caspase-8-deficient mice. In contrast, phosphomimetic YY1-S247D restored these endpoints even when hepatocyte caspase-8 was lacking. Studies in primary mouse and human hepatocytes and human MASH liver specimens supported conservation of this signaling pathway. Conclusions: These findings identify YY1 Ser247 phosphorylation as a critical molecular event linking non-apoptotic hepatocyte caspase-8 signaling to METRN induction and MASH fibrosis and define a previously unrecognized DED-SRC-GSK3b-YY1 signaling axis with potential therapeutic relevance.

cell biology↗

bioRxiv2026

Liver Disease Reveals KIF12 as a Critical Regulator of Mitochondria, Lysosome and Cilia Localization

Pathogenic variants in kinesin family member 12 (KIF12) cause pediatric liver disease, yet the cellular mechanisms underlying this phenotype remain unknown. Here we show that KIF12 expression in the healthy human liver is primarily detected in biliary epithelial cells, as revealed by single cell RNA-sequencing data. To investigate its role in biliary pathology, we introduced a homozygous KIF12 p.Arg219* mutation into induced pluripotent stem cells (iPSCs), which were differentiated into 2D cholangiocyte-like cells (iCCs) and 3D biliary organoids. Pioneering single-molecule fluorescence microscopy in live iCCs, we observed wildtype KIF12 co-localizing with microtubules, consistent with its predicted role as a microtubule-associated motor protein. Our data reveals that KIF12 dysfunction causes abnormal perinuclear clustering of mitochondria and lysosomes, and mislocalization of primary cilia in cholangiocytes. Restoration of wildtype KIF12 expression in mutant KIF12 iCCs rescued organelle positioning and normalized GGT activity. This study uncovers a novel link between KIF12 dysfunction and organelle dynamics in human cholangiocytes, extending our understanding of kinesin roles beyond their established functions in neuronal systems. Our findings provide new insights into the pathogenesis of KIF12-related cholestatic liver disease and lay the groundwork for developing targeted genetic therapies.

genetics↗

bioRxiv2024

Comparison of Wild-Type and High-risk PNPLA3 variants in a Human Biomimetic Liver Microphysiology System for Metabolic Dysfunction-associated Steatotic Liver Disease Precision Therapy

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a worldwide health epidemic with a global occurrence of approximately 30%. The pathogenesis of MASLD is a complex, multisystem disorder driven by multiple factors including genetics, lifestyle, and the environment. Patient heterogeneity presents challenges for developing MASLD therapeutics, creation of patient cohorts for clinical trials and optimization of therapeutic strategies for specific patient cohorts. Implementing pre-clinical experimental models for drug development creates a significant challenge as simple in vitro systems and animal models do not fully recapitulate critical steps in the pathogenesis and the complexity of MASLD progression. To address this, we implemented a precision medicine strategy that couples the use of our liver acinus microphysiology system (LAMPS) constructed with patient-derived primary cells. We investigated the MASLD-associated genetic variant PNPLA3 rs738409 (I148M variant) in primary hepatocytes, as it is associated with MASLD progression. We constructed LAMPS with genotyped wild type and variant PNPLA3 hepatocytes together with key non-parenchymal cells and quantified the reproducibility of the model. We altered media components to mimic blood chemistries, including insulin, glucose, free fatty acids, and immune activating molecules to reflect normal fasting (NF), early metabolic syndrome (EMS) and late metabolic syndrome (LMS) conditions. Finally, we investigated the response to treatment with resmetirom, an approved drug for metabolic syndrome-associated steatohepatitis (MASH), the progressive form of MASLD. This study using primary cells serves as a benchmark for studies using "patient biomimetic twins" constructed with patient iPSC-derived liver cells using a panel of reproducible metrics. We observed increased steatosis, immune activation, stellate cell activation and secretion of pro-fibrotic markers in the PNPLA3 GG variant compared to wild type CC LAMPS, consistent with the clinical characterization of this variant. We also observed greater resmetirom efficacy in PNPLA3 wild type CC LAMPS compared to the GG variant in multiple MASLD metrics including steatosis, stellate cell activation and the secretion of pro-fibrotic markers. In conclusion, our study demonstrates the capability of the LAMPS platform for the development of MASLD precision therapeutics, enrichment of patient cohorts for clinical trials, and optimization of therapeutic strategies for patient subgroups with different clinical traits and disease stages.

cell biology↗

bioRxiv2023

Human Induced Pluripotent Stem Cell based Hepatic-Modeling of Lipid metabolism associated TM6SF2 E167K variant

BACKGROUND AND AIMSTM6SF2 rs58542926 (E167K) is associated with an increase in the prevalence of Metabolic Disfunction-Associated Steatotic Liver Disease (MASLD). Despite all the investigation related to the role of this variant in lipid metabolism, conflicting results in mouse studies underscore the importance of creating a human model for understanding the TM6SF2 mechanism. Therefore, the aim of this study is to generate a reliable human in vitro model that mimic the effects of the TM6SF2 E167K mutation and can be used for future mechanism studies. APPROACH AND RESULTSWe performed gene editing on human-induced pluripotent stem cells (iPSC) derived from a healthy individual to obtain the cells carrying the TM6SF2 E167K mutation. After hepatic differentiation, a decrease in TM6SF2 protein expression was observed in the mutated-induced hepatocyte. An increase in intracellular lipid droplets and a decrease in the efflux of cholesterol and ApoB100 were also observed. Transcriptomics analysis showed up-regulation of genes related to the transport, flux, and oxidation of lipids, fatty acids, and cholesterol in TM6SF2 E167K cells. Additionally, signs of cellular stress were observed in the ER and mitochondria. CONCLUSIONSOur findings indicate that induced hepatocytes generated from iPSC carrying the TM6SF2 E167K recapitulate the effects observed in human hepatocytes from individuals with the TM6SF2 mutation. This study characterizes an in vitro model that can be used as a platform to help in the identification of potential clinical targets and therapies and to understand the mechanism by which the TM6SF2 E167K variant leads to vulnerability to MASLD.

cell biology↗