Biology subjects

Roh, H. C.

Publications and source records attributed to Roh, H. C..

7 recordsLinked to original sources

bioRxiv2026

Lrat-Cre Exhibits Widespread Expression Beyond Hepatic Stellate Cells Across Multiple Tissues

Hepatic stellate cells (HSCs) play a central role in liver fibrosis, shifting from quiescent vitamin A-storing cells to activated, myofibroblast-like cells that secrete collagen and other profibrotic factors1. HSCs have thus become a major focus in liver fibrosis research, and several Cre driver lines have been created to target HSCs in mice. However, early Cre lines had significant limitations. Glial fibrillary acidic protein (Gfap)-Cre labels only a subset of HSCs and also induces recombination in cholangiocytes2. Collagen type I alpha 1 (Col1a1)-Cre and alpha-smooth muscle actin (SMA)-Cre/CreERT2 primarily label activated myofibroblasts and broadly mark portal fibroblasts and vascular smooth muscle cells3,4. Platelet-derived growth factor receptor beta (Pdgfr{beta})-Cre reliably labels HSCs but also recombines pericytes and smooth muscle cells, limiting its specificity5. The introduction of lecithin-retinol acyltransferase (Lrat)-Cre marked a major advance, offering highly specific labeling of quiescent and activated HSCs and rapidly becoming the most widely used driver for HSC tracing and genetic perturbation2. However, the extrahepatic expression of Lrat-Cre remains incompletely understood. This is a critical limitation, given that liver biology is closely coordinated with other organs to maintain systemic metabolism. Addressing these gaps is essential for the accurate interpretation of HSC-specific genetic models in liver biology.

pathology↗

bioRxiv2025

Tirzepatide Synergizes with Leptin on Weight Loss and Restoring Metabolic Homeostasis in Diet-induced Obesity Model

Leptin resistance limits anti-obesity efficacy. We identified a leptin-sensitizing mechanism through tirzepatide (TZP), a glucagon-like peptide-1 receptor (GLP-1R) and glucose-dependent insulinotropic polypeptide receptor (GIPR) dual-agonist. Our tirzepatide clinical trial revealed that circulating leptin levels at baseline correlated with weight loss efficacy in patients with obesity, suggesting leptin and tirzepatide could interact to achieve stronger effects on weight loss. Next, we utilized the diet-induced obesity (DIO) mice and demonstrated the synergistic effects of tirzepatide and leptin combination (TZP+Lep) on weight loss. TZP+Lep treatment further improved hepatic insulin sensitivity and upregulated thermogenetic gene expression in brown adipose tissue. Metabolic profiling under thermoneutrality revealed TZP+Lep treatment further reduced food intake and increased energy expenditure. Tirzepatide sensitized leptin signaling in hypothalamic pro-opiomelanocortin (POMC) and GLP-1R expressing neurons. TZP+Lep synergistically increased POMC neuronal firing by decreasing the inhibitory postsynaptic input. Together, our work showed combining tirzepatide and leptin as a potential way for better maintenance of metabolic homeostasis in obesity management. HighlightsO_LITirzepatide and leptin synergistically promote weight loss through reduced food intake and increased energy expenditure. C_LIO_LITirzepatide and leptin synergistically improve insulin sensitivity and metabolic homeostasis with altered hepatic and adipose gene expression. C_LIO_LITirzepatide sensitizes leptin signaling in hypothalamic GLP-1R and POMC neurons. C_LIO_LITirzepatide and leptin synergistically increase POMC neuronal firing by decreasing inhibitory postsynaptic input. C_LI

neuroscience↗

bioRxiv2025

EPHB2 promotes diet-induced MASH liver fibrosis

The EphB2 receptor tyrosine kinase is thought to participate in numerous fibroinflammatory disorders. In metabolic dysfunction-associated steatohepatitis (MASH), we find EphB2 becomes strongly overexpressed and overactive in hepatic stellate cells (HSCs) from humans with the disease and from mice fed liver-injuring high fat diets. Genetic deletion of EphB2 or inactivation of its tyrosine kinase catalytic domain suppressed diet-induced MASH fibrosis, while a kinase overactive point mutant displayed exacerbated steatosis and hepatic damage. Silencing EphB2 in primary HSCs dampened the ability of TGF-{beta}/SMAD signals to stimulate the transdifferentiation of stellate cells into profibrotic myofibroblasts, and HSC-specific deletion of the receptor, but not hepatocyte deletion, reduced liver scarring in multiple mouse models, even after fibrosis was established. Finally, a newly developed small molecule tetramerization inhibitor that targets EphB2-Ephrin receptor-ligand interactions effectively blunts inflammation and fibrosis in chemical and diet-induced liver injury models, demonstrating that therapeutically targeting EphB2 can counter MASH fibrosis.

pathology↗

bioRxiv2025

Pancreatic Cancer Induces Population-Specific Switching of Myosin Isoforms and Discrete Activation of Cachexia Genes in Skeletal Muscle Myocytes

Skeletal muscle loss in pancreatic cancer is a significant cause of morbidity and mortality for patients. In order to understand myocytes changes we examined myonuclei- and myofiber-specific dynamics during pancreatic cancer cachexia progression. Single-nucleus RNA-seq was used to interrogate myonuclear gene expression, and RNAscope and immunofluorescence characterized myofiber-specific changes. Bulk RNA-seq of skeletal muscle provided a whole-muscle transcriptomic profile. Cachexia induces a progressive loss of muscle differentiation factor Maf and its target Myh4, accompanied by increased expression of Myh1 and Myh2. This myofiber dedifferentiation occurs without evidence for fiber type shifting, regeneration, or proliferation. Single-nuclei analysis reveals global shifts in myofiber gene expression identity including the identification of a cachexia only myonuclear subpopulation. Cachexia gene expression was not restricted solely to this PDAC-specific myonuclear subpopulation and did not overlap with Myh1 and Myh2 expressing myonuclei early in cachexia. Altogether, PDAC cachexia elicits distinct transcriptional responses across different myonuclear populations. These results reveal population-specific heterogeneity in cachexia gene activation, rather than a uniform upregulation of cachexia mediators across muscle tissue. Our data suggest that myonuclei fate occurs prior to overt muscle wasting when cachexia gene expression only modestly overlaps with differentiation factors, with a strong association after irreversible muscle wasting. These findings explain the challenge of effectively targeting skeletal muscle wasting in cancer cachexia requires addressing the changing cell population induced through non overlapping mechanisms.

cancer biology↗

bioRxiv2025

In vivo pulse-chase in C. elegans reveals intestinal histone turnover changes upon starvation

The ability to study protein dynamics and function in the authentic context of a multicellular organism is paramount to better understand biological phenomena in animal health and disease. Pulse-chase of self-labeling fusion protein tags provide the opportunity to label proteins of interest and track those proteins over time. There are currently several challenges associated with performing in vivo protein pulse-chase in animals, such as cost, reproducibility, and accurate detection methods. The C. elegans model organism has attributes that alleviate many of these challenges. This work tests the feasibility of applying the Halo modified enzyme (HaloTag) for in vivo protein pulse-chase in C. elegans. HaloTag intestinal histone reporters were created in the worm and used to demonstrate that reporter protein could be efficiently pulse-labeled by soaking animals in ligand. Labeled protein stability could be monitored over time by fluorescent confocal microscopy. Further investigation revealed reporter protein stability was dependent on the animals nutritional state. Chromatin Immunoprecipitation and sequencing (ChIP-seq) of the reporters showed incorporation in chromatin with little change hours into starvation, implying a lack of chromatin regulation at the time point tested. Collectively, this work presents a straightforward method to label and track proteins of interest in C. elegans that can address a multitude of biological questions surrounding protein stability and dynamics in this animal model.

biochemistry↗

bioRxiv2023

Uncoupling protein 1-driven Cre (Ucp1-Cre) is expressed in the epithelial cells of mammary glands and various non-adipose tissues

ObjectiveUncoupling protein 1 (UCP1), a mitochondrial protein responsible for nonshivering thermogenesis in adipose tissue, serves as a distinct marker for thermogenic brown and beige adipocytes. Ucp1-Cre mice are thus widely used to genetically manipulate these thermogenic adipocytes. However, evidence suggests that UCP1 may also be expressed in non-adipocyte cell types. In this study, we investigated the presence of UCP1 expression in different mouse tissues that have not been previously reported. MethodsWe employed Ucp1-Cre mice crossed with Cre-inducible transgenic reporter Nuclear tagging and Translating Ribosome Affinity Purification (NuTRAP) mice, to investigate Ucp1-Cre expression in various tissues of adult female mice and developing embryos. Tamoxifen-inducible Ucp1-CreERT2 mice crossed with NuTRAP mice were used to assess active UCP1 expression. Immunostaining, RNA analysis, and single-cell/nucleus RNA-seq (sc/snRNA-seq) data analysis were performed to determine the expression of endogenous UCP1 and Ucp1-Cre-driven reporter expression. We also investigated the impact of UCP1 deficiency on mammary gland development and function using Ucp1-knockout (KO) mice. ResultsUcp1-Cre expression was observed in the mammary glands within the inguinal white adipose tissue of female Ucp1-Cre; NuTRAP mice. However, endogenous Ucp1 was not actively expressed as Ucp1-CreERT2 failed to induce the reporter expression in the mammary glands. Ucp1-Cre was activated during embryonic development in various tissues, including mammary glands, as well as in the brain, kidneys, eyes, and ears, specifically in epithelial cells in these organs. While sc/snRNA-seq data suggest potential expression of UCP1 in mammary epithelial cells in adult mice and humans, Ucp1-KO female mice displayed normal mammary gland development and function. ConclusionsOur findings reveal widespread Ucp1-Cre expression in various non-adipose tissue types, starting during early development. These results highlight the importance of exercising caution when interpreting data and devising experiments involving Ucp1-Cre mice.

developmental biology↗

bioRxiv2020

Obesity-linked PPARγ S273 phosphorylation promotes insulin resistance through Growth Differentiation Factor 3

Overnutrition and obesity promote adipose tissue dysfunction, often leading to systemic insulin resistance. The thiazolidinediones (TZDs) are a potent class of insulin-sensitizing drugs and ligands of PPAR{gamma} that improve insulin sensitivity, but their use is limited due to significant side effects. Recently, we demonstrated a mechanism by which TZDs improve insulin sensitivity distinct from receptor agonism and adipogenesis: reversal of obesity-linked phosphorylation of PPAR{gamma} at Serine 273. However, the role of this modification has not been tested genetically. Here we demonstrate that mice encoding an allele of PPAR{gamma} which cannot be phosphorylated at S273 are protected from insulin resistance, without exhibiting differences in body weight or TZD-associated side effects. Indeed, hyperinsulinemic-euglycemic clamp experiments confirm improved insulin sensitivity, as evidenced by increased whole-body glucose uptake. RNA-seq experiments reveal PPAR{gamma} S273 phosphorylation specifically enhances transcription of Gdf3, a BMP family member. Ectopic expression of Gdf3 is sufficient to induce insulin resistance in lean, healthy mice. We find that Gdf3 can impact metabolism by inhibition of BMP signaling. Together, these results highlight the diabetogenic role of PPAR{gamma} S273 phosphorylation and focuses attention on a putative target, Gdf3.

cell biology↗