Biology subjects

Korinek, V.

Publications and source records attributed to Korinek, V..

11 recordsLinked to original sources

bioRxiv2025

Canonical Wnt signaling controls the fate and plasticity of NG2 glia in the healthy and ischemic adult mouse cortex

NG2 glia, also known as oligodendrocyte precursor cells (OPCs), exhibit unexpected plasticity in the adult brain after injury, yet the molecular cues guiding their fate remain poorly defined. Wnt signaling contributes to tissue responses following ischemic stroke, but its precise role in post-injury glial remodeling is not fully understood. Here, we define how Wnt/{beta}-catenin signaling shapes NG2 glial behavior after focal cerebral ischemia. Using genetic mouse models enabling cell-specific Wnt pathway activation or inhibition, combined with single-cell RNA sequencing, immunohistochemistry, and electrophysiological recording, we disclosed a central role for Wnt signaling in post-injury fate specification. We identified 12 transcriptionally distinct subpopulations within the oligodendroglial lineage, including a subset with an astrocyte-like transcriptional profile. Wnt signaling strongly influenced the balance between OPC proliferation and differentiation: pathway hyperactivation impaired oligodendrocyte maturation and expanded astrocyte-like NG2-derived cells, likely through concomitant activation of the Notch pathway. Remarkably, Wnt hyperactivation also induced the appearance of cholinergic neuron-like cells derived from NG2-expressing cells exclusively in the somatosensory cortex; these cells generated action potentials and exhibited sodium conductance characteristic of functional neurons. Together, these findings demonstrate that NG2 glia undergo distinct fate transitions after stroke and that their lineage plasticity is highly sensitive to Wnt pathway dynamics. Targeted fine-tuning of Wnt/{beta}-catenin signaling may enable directed redirection of NG2 glia toward specific reparative outcomes, including neuronal reprogramming, in the injured adult brain. TEASERWnt activation promotes neuronal conversion of NG2 glia, while impairing oligodendrocyte maturation.

neuroscience↗

bioRxiv2024

Development of a new flippase-dependent mouse model for red fluorescence-based isolation of KrasG12D oncogene-expressing tumor cells

Proto-oncogene KRAS, GTPase (KRAS) is one of the most intensively studied oncogenes in cancer research. Although several mouse models allow for regulated expression of mutant Kras, selective isolation and analysis of transforming or tumor cells that produce the Kras oncogene remains a challenge. In our study, we present a knock-in model of oncogenic variant KrasG12D that enables the "activation" of KrasG12D expression together with production of red fluorescent protein tdTomato. Both proteins are expressed from the endogenous Kras locus after recombination of a transcriptional stop box in the genomic DNA by the enzyme flippase (Flp). We have demonstrated the functionality of the allele termed RedRas (abbreviated KrasRR) under in vitro conditions with mouse embryonic fibroblasts and organoids and in vivo in the lung and colon epithelium. After recombination with adenoviral vectors carrying the Flp gene, the KrasRR allele itself triggers formation of lung adenomas. In the colon epithelium, it causes the progression of adenomas that are triggered by the loss of tumor suppressor adenomatous polyposis coli (Apc). Importantly, cells in which recombination has successfully occurred can be visualized and isolated using the fluorescence emitted by tdTomato. Furthermore, we show that KrasG12D production enables intestinal organoid growth independent of epidermal growth factor (EGF) signaling and that the KrasG12D function is effectively suppressed by specific inhibitor MRTX1133.

cancer biology↗

bioRxiv2024

The fate of secretory cells during intestinal homeostasis, regeneration, and tumor formation is regulated by Tcf4

The single-layer epithelium of the gastrointestinal tract is a dynamically renewing tissue that ensures nutrient absorption, secretory and barrier functions and is involved in immune responses. The basis for this homeostatic renewal is the Wnt signaling pathway. Blocking this pathway can lead to epithelial damage, while its abnormal activation can result in the development of intestinal tumors. In this study, we investigated the dynamics of intestinal epithelial cells and tumorigenesis using a conditional mouse model. Using single-cell and bulk RNA sequencing and histological analysis, we elucidated the cellular responses following the loss of specific cell types. We focused on the fate of cells in the lower parts of the intestinal crypts and the development of colon adenomas. By partially inactivating the transcription factor Tcf4, a key effector of the Wnt signaling pathway, we analyzed the regeneration of isolated hyperproliferative foci (crypts). Our results suggest that the damaged epithelium is not restored by a specific regeneration program associated with oncofetal gene production, but rather by a standard homeostatic renewal pathway. Moreover, disruption of Tcf4 in secretory progenitors resulted in a significant shift in the cell lineage from Paneth cells to goblet cells, characterized by morphological changes and loss of Paneth cell-specific genes. We also found that hyperactivation of the Wnt signaling pathway in colonic adenomas correlated with the upregulation of genes typical of Paneth cells in the intestine, followed by the emergence of secretory tumor cells producing the Wnt3 ligand. The absence of Tcf4 led to a phenotypic shift of the tumor cells towards goblet cells. Our study presents a new model of epithelial regeneration based on the genetically driven partial elimination of intestinal crypts. We highlight the critical role of Tcf4 in the control of cell lineage decisions in the intestinal epithelium and colon tumors. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=160 HEIGHT=200 SRC="FIGDIR/small/603019v1_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@1d8e5a0org.highwire.dtl.DTLVardef@cb85f7org.highwire.dtl.DTLVardef@1c84ed3org.highwire.dtl.DTLVardef@1af36f3_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2023

Astrocyte-like subpopulation of NG2 glia in the adult mouse cortex exhibits characteristics of neural progenitor cells and is capable of forming neuron-like cells after ischemic injury

Glia cells expressing neuron-glial antigen 2 (NG2) play a critical role as oligodendrocyte precursor cells (OPCs) in the healthy brain; however, their differentiation potential after ischemic injury remains an unresolved question. Here, we aimed to elucidate the heterogeneity and role of NG2 glia in the ischemic brain. We used transgenic mice to label NG2-expressing cells and their progeny with red fluorescent protein tdTomato in the healthy brains and those after focal cerebral ischemia (FCI). Based on single-cell RNA sequencing, the labeled glial cells were divided into five distinct subpopulations. The identity of these subpopulations was determined based on gene expression patterns. In addition, membrane properties were further analyzed using the patch-clamp technique. Three of the observed subpopulations represented OPCs, whereas the fourth group exhibited characteristics of cells destined for oligodendrocyte fate. The fifth subpopulation of NG2 glia carried astrocytic markers. Importantly, we detected features of neural progenitors in these cells. This subpopulation was present in both healthy and post-ischemic tissue; however, its gene expression changed after ischemia, with genes related to neurogenesis being more abundant. Neurogenic gene expression was monitored over time and complemented by immunohistochemical staining, which showed increased numbers of Purkinje cell protein 4-positive NG2 cells at the edge of the ischemic lesion 12 days after FCI, and NeuN-positive NG2 cells 28 days after injury, indicating the existence of neuron-like cells that develop from NG2 glia in the ischemic tissue. Our results provide further insight into the differentiation plasticity and neurogenic potential of NG2 glia after stroke. Main PointsO_LIDifferent subpopulations of NG2 glia in the healthy and ischemic adult cortex were identified based on their gene expression and membrane properties. C_LIO_LIAstrocyte-like NG2 glia exhibit neurogenic gene expression and are more abundant in post-ischemic tissue. C_LIO_LIProgeny of NG2-positive cells carrying neuronal marker NeuN was observed at the edge of the ischemic lesion. C_LI

neuroscience↗

bioRxiv2022

Terminal differentiation of enterocytes is governed by distinct members of Tgfβ superfamily

The protective and absorptive functions of the intestinal epithelium rely on differentiated enterocytes in the villi. The differentiation of enterocytes is orchestrated by sub-epithelial mesenchymal cells producing distinct ligands along the villus axis, in particular Bmps and Tgf{beta}. Here we show that individual Bmp ligands and Tgf{beta} drive distinct enterocytic programs specific to villus zonation. Bmp4 is expressed mainly from the center to the upper part of the villus, and it activates preferentially genes connected to lipid uptake and metabolism. In contrast, Bmp2 is produced by villus-tip mesenchymal cells, and it influences the adhesive properties of villus-tip epithelial cells and the expression of immunomodulators. Hence, Bmp2 promotes the terminal enterocytic differentiation at the villus-tip. Additionally, Tgf{beta} induces epithelial gene expression programs similar to that triggered by Bmp2. The inhibition of Bmp receptor type I in vivo and using intestinal organoids lacking Smad4 revealed that Bmp2-driven villus-tip program is activated by a canonical Smad-dependent mechanism. Finally, we established an organoid cultivation system that enriches for villus-tip enterocytes and thereby better mimics the cellular composition of the intestinal epithelium. Altogether our data suggest that not only Bmp gradient, but also the activity of individual Bmp drives specific enterocytic programs.

cell biology↗

bioRxiv2022

TROP2 represents a negative prognostic factor in colorectal adenocarcinoma and its expression is associated with features of epithelial-mesenchymal transition and invasiveness

Trophoblastic cell surface antigen 2 (TROP2) is a membrane glycoprotein overexpressed in many solid tumors with poor prognosis, including intestinal neoplasms. In our study, we show that TROP2 is expressed in preneoplastic lesions and its expression is maintained in most colorectal cancer (CRC). High TROP2 positivity correlated with lymph node metastases and poor tumor differentiation and was a negative prognostic factor. To investigate the role of TROP2 in intestinal tumors, we analyzed two mouse models with conditional disruption of the adenomatous polyposis coli (Apc) tumor suppressor gene, human adenocarcinoma samples, patient-derived organoids, and TROP2-deficient tumor cells. We found that Trop2 is produced early after Apc inactivation and its expression is associated with transcription of genes involved in epithelial-mesenchymal transition, regulation of migration, invasiveness, and extracellular matrix remodeling. A functionally similar group of genes was also enriched in TROP2-positive cells from human CRC samples. To decipher the driving mechanism of TROP2 expression, we analyzed its promoter. In human cells, this promoter was activated by {beta}-catenin and additionally by Yes1-associated transcriptional regulator (YAP). The regulation of TROP2 expression by active YAP was verified by YAP knockdown in CRC cells. Our results suggest a possible link between aberrantly activated Wnt/{beta}-catenin signaling, YAP, and TROP2 expression. Simple SummaryColorectal cancer (CRC) is one of the most common cancers worldwide. While systemic treatment of CRC is based on chemotherapy, subsequent therapeutic options are far less effective. Trophoblast cell surface antigen 2 (TROP2) is highly expressed in many carcinomas, including CRC, where its expression correlates with poor prognosis. Anti-TROP2-targeted therapy was approved for the treatment of breast and urothelial carcinomas. We aimed to determine whether TROP2 is a suitable target for the treatment of CRC. We demonstrated that TROP2 expression in CRC correlates with lymph node metastasis and poor tumor differentiation. Analysis of mouse tumor models, patient-derived organoids, and tumor cells revealed that TROP2 expression is associated with features related to epithelial-mesenchymal transition and invasiveness. Our results suggest that TROP2 targeting may be a promising approach, especially in the early phase of treatment.

cancer biology↗

bioRxiv2022

Tumor suppressor Hypermethylated in Cancer 1 represses expression of cell cycle regulator E2F7 in human primary cells

Hypermethylated in Cancer 1 (HIC1) is an established tumor suppressor, which is frequently inactivated in various cancers. In colorectal carcinoma (CRC), silencing of HIC1 has been recognized as one of the important events in malignant tumor progression. Strikingly, CRC patients with high HIC1 expression have a worse prognosis than patients with relatively low HIC1 mRNA levels. To analyze the function of HIC1, we performed expression profiling of human primary fibroblasts after downregulation of HIC1 by RNA interference. We show that HIC1 deficiency triggers a p53-dependent response and that disruption of the HIC1 gene in human colon cells delays cell cycle progression under serum deficiency conditions. Moreover, treatment with etoposide, a DNA-damaging agent, significantly impairs the proliferation rate and dynamics of damaged DNA repair in HIC1-deficient compared with wild-type cells. One of the genes upregulated in HIC1-depleted cells encodes cell cycle regulator E2F7. E2F7 is an atypical member of the E2F family, which functions primarily as a transcriptional repressor, and its downregulation is essential for proper cell cycle progression and expression of genes involved in DNA repair. We demonstrated that E2F7 is indeed the target of transcriptional repression mediated by HIC1. Moreover, our results suggest that the phenotypic manifestations associated with loss of the HIC1 gene, in particular the changes in cell cycle progression and slowed repair of damaged DNA, are caused by dysregulation of E2F7 expression. Finally, we observed an inverse relationship between HIC1 and E2F7 in a panel of CRC. Importantly, CRC patients who express relatively high levels of E2F7 have a remarkably better prognosis than patients with intermediate or low levels of E2F7 expression.

cancer biology↗

bioRxiv2020

Plectin Ensures Intestinal Epithelial Integrity and Protects Colon Against Colitis

Plectin, a highly versatile cytolinker protein, provides tissues with mechanical stability through the integration of intermediate filaments (IFs) with cell junctions. Here, we hypothesize that plectin-controlled cytoarchitecture is a critical determinant of the intestinal barrier function and homeostasis. Mice lacking plectin in intestinal epithelial cells (IEC; Ple{Delta}IEC) spontaneously developed colitis characterized by extensive detachment of IECs from the basement membrane (BM), increased intestinal permeability, and inflammatory lesions. Moreover, plectin expression was reduced in colons of ulcerative colitis (UC) patients and negatively correlated with the severity of colitis. Mechanistically, plectin deficiency in IECs led to aberrant keratin filament (KF) network organization and formation of dysfunctional hemidesmosomes (HDs) and intercellular junctions. In addition, the hemidesmosomal 6{beta}4 integrin (Itg) receptor showed attenuated association with KFs, and protein profiling revealed prominent downregulation of junctional constituents. Consistent with effects of plectin loss in the intestinal epithelium, plectin-deficient IECs exhibited remarkably reduced mechanical stability and limited adhesion capacity in vitro. Feeding mice with a low-residue liquid diet that reduced mechanical stress and antibiotic treatment successfully mitigated epithelial damage in the Ple{Delta}IEC colon.

molecular biology↗

bioRxiv2019

Pathogenic potential of Hic1 expressing cardiac stromal progenitors

The cardiac stroma contains multipotent mesenchymal progenitors. However, lineage relationships within cardiac stromal cells are still poorly understood. Here, we identify heart-resident PDGFRa+ Sca-1+ cells as cardiac Fibro/Adipogenic Progenitors (cFAPs) and show that they respond to ischemic damage by generating fibrogenic cells. Pharmacological blockade of this differentiation step with an anti-fibrotic tyrosine kinase inhibitor decreases post-myocardial infarction (MI) remodeling and leads to improvements in heart function. In the undamaged heart, activation of cFAPs through lineage-specific deletion of the quiescence factor Hic1 reveals additional pathogenic potential, causing fibro-fatty infiltration of the myocardium and driving major pathological features of Arrhythmogenic Cardiomyopathy (AC). HighlightsO_LIA subpopulation of PDGFRa+, Sca-1+ cells, previously considered to be a sub-type of cardiac fibroblasts, are multipotent mesenchymal progenitors, C_LIO_LICardiac damage triggers the differentiation of PDGFRa+ Sca-1+ cells into Sca-1- cells expressing a fibrogenic transcriptional programme, C_LIO_LIBlockade of the cFAP-to-fibroblast transition by Nilotinib ameliorated cardiac dysfunction post-MI and modulated cardiac remodelling. C_LIO_LIStudies performed on a model of experimentally-induced AC confirmed that cFAPs are a source of both cardiac fibroblasts and adipocytes in vivo. C_LIO_LIConversely, in the undamaged heart, activation of cFAPs by means of lineage-specific deletion of transcription factor Hic1, resulted in fibro/fatty cardiac degeneration and pathological alterations reminiscent of AC. Collectively, our findings show that a proportion of what are commonly termed "fibroblasts" are actually multipotent mesenchymal progenitors that contribute to different forms of cardiac degeneration depending on the damage setting. C_LI

cell biology↗

bioRxiv2017

HIC1 links retinoic acid signalling to group 3 innate lymphoid cell-dependent regulation of intestinal immunity and homeostasis

The intestinal immune system must be able to respond to a wide variety of infectious organisms while maintaining tolerance to non-pathogenic microbes and food antigens. The Vitamin A metabolite retinoic acid (RA) has been implicated in the regulation of this balance, partially by regulating innate lymphoid cell (ILC) responses in the intestine. However, the molecular mechanisms of RA-dependent intestinal immunity and homeostasis remain elusive. Here we define a role for the transcriptional repressor Hypermethylated in cancer 1 (HIC1, ZBTB29) in the regulation of ILC responses in the intestine. Intestinal ILCs express HIC1 in a vitamin A-dependent manner. In the absence of HIC1, group 3 ILCs (ILC3s) are lost, resulting in increased susceptibility to infection with the bacterial pathogen Citrobacter rodentium. In addition, the loss of ILC3s leads to a local and systemic increase in IFN-{gamma}-producing T cells that prevents the development of protective immunity against infection with the parasitic helminth Trichuris muris. Thus, RA-dependent expression of HIC1 in ILC3s regulates intestinal homeostasis and protective immunity.\n\nAuthor SummaryInnate lymphoid cells (ILCs) are emerging as important regulators of immune responses at barrier sites such as the intestine. However, the molecular mechanisms that control this are not well described. In the intestine, the Vitamin A metabolite retinoic acid (RA) has been shown to be an important component of the homeostatic mechanisms. In this manuscript, we show that the RA-dependent transcription factor Hypermethylated in cancer 1 (HIC1, ZBTB29) is required for ILC homeostasis and function in the steady state as well as following infection with the bacterial pathogen Citrobacter rodentium or the helminth parasite Trichuris muris. Thus, HIC1 links RA signalling to intestinal immune responses. Further, our results identify HIC1 as a potential target to modulate ILC responses in vivo in health and disease.

immunology↗

bioRxiv2016

The transcriptional repressor HIC1 regulates intestinal immune homeostasis

The intestine is a unique immune environment that must respond to infectious organisms but remain tolerant to commensal microbes and food antigens. However, the molecular mechanisms that regulate immune cell function in the intestine remain unclear. Here we identify the POK/ZBTB family transcription factor Hypermethylated in cancer 1 (HIC1, ZBTB29) as a central component of immunity and inflammation in the intestine. HIC1 is specifically expressed in immune cells in the intestinal lamina propria (LP) in the steady state and mice with a T cell-specific deletion of HIC1 have reduced numbers of T cells in the LP. HIC1 expression is regulated by the Vitamin A metabolite retinoic acid, as mice raised on a Vitamin A-deficient diet lack HIC1-positive cells in the intestine. HIC1-deficient T cells overproduce IL-17A in vitro and in vivo, and fail to induce intestinal inflammation, identifying a critical role for HIC1 in the regulation of T cell function in the intestinal microenvironment under both homeostatic and inflammatory conditions.

immunology↗