Biology subjects

Penners, C.

Publications and source records attributed to Penners, C..

3 recordsLinked to original sources

bioRxiv2026

Cyclin E/CDK2 deficiency links cell cycle control to intestinal barrier integrity and tight junction regulation

Background & Aims: The intestinal epithelium renews continuously through cell cycle-dependent turnover, yet it remains unknown whether core cell cycle regulators directly control intestinal barrier function. We investigated how loss of the Cyclin E1/Cyclin E2/CDK2 complex affects intestinal homeostasis. Based on the important role of this complex in compensatory liver regeneration, we hypothesized that its combined loss would impair epithelial renewal and barrier integrity. Methods: We generated Ccne2-/- mice and triple knockout (TKO) mice with intestinal epithelial cell (IEC)-specific deletion of Ccne1 and Cdk2 on a constitutive Ccne2-null background and characterized intestinal architecture, proliferation, and barrier function using histology, immunoblotting, qPCR, and FITC-dextran permeability assays. Mechanistic findings were validated in CRISPR/Cas9-generated Ccne2-deficient and CDK1-overexpressing MC38 colon carcinoma cells using transcriptomics and kinomics approaches. Results: Contrary to our hypothesis, TKO maintained and Ccne2-/- mice even enhanced cell cycle activity selectively in the colon, along with enhanced Cdk1 expression, had significantly lower serum FITC-dextran levels after oral administration, and increased Tjp1/ZO-1 expression, consistent with reduced intestinal permeability. Ccne2-deficient MC38 cells recapitulated the increase in ZO-1 and exhibited transcriptional enrichment of gene sets associated with tight junctions and cell cycle. CDK1 overexpression in MC38 cells increased ZO-1 protein abundance and was associated with activation of an AMPK-related kinase network. In TKO and Ccne2-/- colonic epithelium, CDK1, phosphorylated AMPK and ZO-1 showed partial colocalization at lateral epithelial cell-cell contacts. Conclusions: Loss of Cyclin E2, either alone or in combination with epithelial Cyclin E1/CDK2 deficiency, is associated with increased CDK1 expression and strengthens the colonic barrier integrity in mice. Findings from MC38 cells suggest that transcriptional reprogramming and enhanced CDK1 signaling in the context of Cyclin E2 deficiency may contribute to tight junction reinforcement and improved barrier function.

cell biology↗

bioRxiv2026

The cell cycle regulator Cyclin E1 drives macrophage-associated inflammatory responses in acute immune-mediated hepatitis

Background and aims: Cyclin E1 is a canonical regulator of cell cycle progression known to promote liver fibrosis and hepatocarcinogenesis. However, its precise contribution to hepatic immune responses remains poorly understood. We investigated whether Cyclin E1 regulates macrophage-associated inflammation and acute immune-mediated liver injury. Methods: Hepatic immune populations were analyzed in untreated and concanavalin A-treated wildtype and constitutive Ccne1-/- mice by flow cytometry. Liver injury was assessed by survival, histopathology, and caspase activation. Inflammatory mediators were quantified by qPCR and ELISA. Bone marrow-derived macrophages were examined during differentiation and pro-inflammatory polarization using flow cytometry, cytokine measurements, and RNA-sequencing. Lipid nanoparticle-mediated delivery of Ccne1-specific siRNA was evaluated in J774A.1 macrophage-like cells. Results: Under homeostatic conditions, Ccne1-/- mice exhibited reduced hepatic immune cell numbers, including Kupffer cells and CD4+ and CD8+ lymphoid cells. Following concanavalin A administration, Ccne1-/- mice showed improved survival, reduced hepatic necrosis, and diminished caspase-3 and caspase-8 activation. Protection was associated with reduced Kupffer and CD8+ lymphoid cell abundance and attenuated inflammatory mediator expression. Cyclin E1 deficiency did not substantially alter bone marrow-derived macrophage differentiation or cell cycle distribution. However, pro-inflammatory Ccne1-/- macrophages showed reduced interleukin-6 expression, attenuated inflammatory gene programs, and lower inferred IRF1 and NF-{kappa}B1 activity. Ccne1 knockdown similarly reduced interleukin-6 expression in pro-inflammatory J774A.1 cells. Conclusions: Cyclin E1 contributes to hepatic immune homeostasis and promotes macrophage-associated inflammatory signaling during immune-mediated hepatitis. Its inflammatory function is uncoupled from overt changes in macrophage cell cycle progression and may involve regulation of IRF1- and NF-{kappa}B-associated transcriptional programs. Targeting Cyclin E1 may therefore provide a strategy to attenuate selected inflammatory responses in liver disease.

cell biology↗

bioRxiv2025

Identification, Purification and Characterization of Mast Cells in Murine Liver Fibrosis: Novel Methods, Expression Signatures and Correlation with Disease Severity

Mast cells (MCs) are myeloid cells of the innate immune system. As a first line of defense, they fulfill effector functions and immune modulatory properties. Upon activation, they release pro-inflammatory mediators such as cytokines and proteases. It has been suggested that MCs may contribute to the development of liver fibrosis. However, investigating hepatic MC biology in mice is challenging due to low MC numbers and a lack of suitable detection techniques relying on MC proteins and their modifications. Here, we evaluated whether the expression strength of MC markers correlates with the degree of liver fibrosis in mice and aimed to determine the frequency and localization of hepatic MCs. We applied both a toxic (DEN/CCl4 treatment) and a genetic (Mdr2-/- mice) liver fibrosis model in C57BL/6 mice and found significant correlations between fibrosis grade and the expression of several established MC markers. These correlations were further supported by data analyses from patients with fibrosis and hepatocellular carcinoma (HCC) using publicly available transcriptomics datasets. We used FACS to purify and isolate MCs from fibrotic mouse livers and verified MC signatures by qPCR analysis of MC-specific gene expression. Hepatic MCs were predominantly negative for Mast Cell Protease 5 (Mcpt5) and occurred at a low frequency (approximately 1-2% of leukocytes). Using Molecular CartographyTM of fibrotic liver sections, we determined the spatial localization, expression signature, abundance (approximately 2 cells/mm2) and cellular environment of murine hepatic MCs. In summary, we demonstrated the existence of MCs in murine fibrotic livers and defined MC expression signatures that correlate with the strength of liver fibrosis. These findings will help to study MC biology in murine models of liver disease more effectively in the future.

cell biology↗