Biology subjects

Liedtke, C.

Publications and source records attributed to Liedtke, C..

8 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↗

bioRxiv2026

A mixture of plant polyphenols unexpectedly aggravates liver metastasis of colorectal cancer in mice

Epidemiological studies suggest that vegetarian diets are associated with lower cancer incidence and mortality, an effect attributed in part to phytochemicals such as polyphenols and carotenoids. Although numerous in vitro experiments and investigations using immunodeficient rodent models report tumor-suppressive activities of phytochemicals, their impact on tumor progression in immunocompetent hosts remains insufficiently understood. Here, we examined the influence of a defined plant phytochemical mixture (PPM) on the growth of colon cancer liver metastases, both in vitro and in immunocompetent mice. Consistent with the prevailing literature, treatment of the murine colon cancer cell line MC38 with the PPM significantly reduced cell proliferation and survival in vitro. Strikingly, however, administration of the PPM to mice bearing MC38-derived hepatic metastases markedly accelerated tumor growth. Immunohistochemical analyses revealed a significantly increased accumulation of immune cells--specifically CD45 leukocytes and F4/80 macrophages--at the periphery of the metastatic lesions in PPM-treated animals. To assess the functional relevance of this inflammatory response, the PPM was combined with the anti-inflammatory drug prednisolone. This intervention resulted in significantly reduced metastatic burden, supporting the notion that the PPM exacerbates tumor progression through enhanced peritumoral inflammation. These findings highlight the importance of validating observations from cell culture and immunodeficient models in fully immunocompetent systems. They further emphasize that the immunomodulatory effects of plant phytochemicals warrant careful and comprehensive investigation.

cancer biology↗

bioRxiv2026

Edge effect on the distribution of the Green Shield Bug Palomena prasina in hazelnut orchards, and the role of adjacent habitats in crop colonization.

Palomena prasina (L.) (Hemiptera: Pentatomidae), the green shield bug (GSB), is an important hazelnut pest in Southern Europe. Currently, its control focuses on insecticide spraying during the crop season. We hypothesised that, as for other pentatomid species, adjacent habitats strongly influence the population build-up in spring and, therefore, lead to edge effects in crop fields during the production season. This could allow for precision-targeted pest management strategies. This study examined the spatio-temporal dynamics of the GSB in spring and summer over two years. We investigated the plant preferences of GSBs in spring and the existence of edge effects on their distribution and on fruit damage in hazelnut orchards in summer. We also examined the relative contribution of adjacent habitats to GSB abundance in crops. Our results show that, following their emergence from overwintering in spring, GSB adults, and later on their offspring, are primarily found on wild host plants in natural habitats, particularly on Crataegus monogyna Jacquin, and Cornus sanguinea L.. In early summer, the older nymphs of the second generation colonise the hazelnut orchards, with populations and damage proportion displaying edge effects. We were unable to identify an adjacent habitat variable that significantly explains the abundance of GSB in the orchards, although both forest habitats and hazelnut orchards have an effect on GSB abundance. Based on these findings, we propose various IPM strategies for controlling P. prasina.

ecology↗

bioRxiv2025

SMAD2 sets divergent thresholds for TGF-β-induced SMAD1/5 signaling and IgE-mediated pro-inflammatory activation of mast cells

ObjectiveTGF-{beta}/SMAD signaling controls mast cell (MC) development and exerts anti-inflammatory functions, while antigen (Ag)-triggered Fc{varepsilon}RI/MAPK activation commands pro-inflammatory processes. SMAD2 is a signaling hub integrating both, TGF-{beta}/ALK5-mediated SMAD2 C-terminal-and ERK-mediated SMAD2 linker-phosphorylation. Here, we analyzed the role of SMAD2 in TGF-{beta}-and Ag-stimulated signaling, and their cross-talk which regulate MC responses. MethodsThe CRISPR-Cas method was used to disable SMAD2 expression in the PMC-306 cell line. The transcriptome of the corresponding cells was analyzed by NGS in homeostatic and stimulated conditions. Activation of signaling intermediates, target gene responses and effector function were analyzed by qPCR, Western blot and ELISAs. The causal association of SMAD2 with the found effects was proven by re-introduction of a tagged SMAD2 in knock out cells. ResultsThe absence of SMAD2 led to increased proliferation and survival, and decreased transcription of target genes like Smad7 and Jun in steady state and upon TGF-{beta} treatment. Intriguingly, SMAD2 was found to regulate TGF-{beta}-mediated SMAD1/5 activation, resulting in augmented expression of Id3 in SMAD2-deficient MCs. Unexpectedly, we found that SMAD2 is indispensable for Ag-triggered production of pro-inflammatory cytokines, such as IL-6 and TNF. Re-introducing SMAD2 restores these events with varying sensitivity depending on the receptor system triggered. ConclusionsOur findings highlight a previously unrecognized role of SMAD2 as a decisive hub in TGF-{beta}-ALK5-SMAD1/5 and Ag-Fc{varepsilon}RI-MAPK signaling, suggesting that pharmacological modulation of SMAD2 activity could be leveraged as regulator of both suppressive and inflammatory MC functions.

immunology↗

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↗

bioRxiv2023

Transformation of primary murine peritoneal mast cells by constitutive KIT activation as a result of lost Cdkn2a/Arf expression

Mast cells (MCs) are immune cells of the myeloid lineage distributed in tissues throughout the body. Phenotypically, they are a heterogeneous group characterized by different protease repertoires stored in secretory granules and differential presence of receptors. To adequately address aspects of MC biology either primary MCs isolated from human or mouse tissue or different human MC lines, like HMC-1.1 and -1.2, or rodent MC lines like L138.8A or RBL-2H3 are frequently used. Nevertheless, cellular systems to study MC functions are very limited. We have generated a murine connective tissue-like MC line, termed PMC-306, derived from primary peritoneal MCs (PMCs), which spontaneously transformed. We analyzed PMC-306 cells regarding MC surface receptor expression, effector functions and respective signaling pathways, and found that the cells reacted very similar to primary wildtype (WT) PMCs. In this regard, stimulation with MAS-related G-protein-coupled receptor member B2 (MRGPRB2) ligands induced respective signaling and effector functions. Furthermore, PMC-306 cells revealed significantly accelerated cell cycle progression, which however was still dependent on IL-3 and stem cell factor (SCF). Phenotypically, PMC-306 cells adopted an immature connective tissue-like MCs appearance. The reason for immortalization most likely is the loss of the two critical cell cycle regulators Cdkn2a/INK4A and Arf/p19, respectively. The loss of Cdkn2a and Arf expression could be mimicked in primary bone marrow-derived mast cells (BMMCs) by SCF supplementation strongly arguing for an involvement of KIT activation in the transformation process. Hence, this new cell line might be a useful tool to study further aspects of PMC function and to address tumorigenic processes associated with MC leukemia.

immunology↗

bioRxiv2019

Mating strategy is determinant of Adenovirus prevalence in European bats

Adenoviruses are double-strained DNA viruses found in a great number of vertebrates, including humans. In order to understand their transmission dynamics, it is crucial, even from a human health perspective, to investigate how host traits influence their prevalence. Bats are important reservoirs for Adenoviruses, and here we use the results of recent screenings in Western Europe to evaluate the association between characteristic traits of bat species and their probability of hosting Adenoviruses, taking into account their phylogenetic relationships. Across species, we found an important phylogenetic component in the presence of Adenoviruses and mating strategy as the most determinant factor conditioning the prevalence of Adenoviruses across bat species. Contrary to other more stable mating strategies (e.g. harems), swarming could hinder transmission of Adenoviruses since this strategy implies that contacts between individuals are too short. Alternatively, bat species with more promiscuous behavior may develop a stronger immune system. Outstandingly high prevalence of Adenoviruses was reported for the Iberian species Pipistrellus pygmaeus, P. kuhlii and Nyctalus lasiopterus and we found that in the latter, males were more likely to be infected by Adenoviruses than females, due to the immunosuppressing consequence of testosterone during the mating season. As a general trend across species, we found that the number of Adenoviruses positive individuals was different across localities and that the difference in prevalence between populations was correlated with their geographic distances (P. pygmaeus). These results increase our knowledge about the transmission mechanisms of Adenoviruses.\n\nAuthor SummaryAdenoviruses are DNA viruses with a wide range of vertebrate hosts, including humans, causing ocular, respiratory and gastrointestinal diseases. Here, we focus on the prevalence of Adenoviruses in bats, which are known to be natural reservoir of many viruses, using the results of recent screenings for prevalence of these viruses in 33 European bat species. Our aim is to find association between Adenoviruses prevalence and biological and behavioral host traits, considering the heterogeneity both between and within species in order to have a deeper understanding of mechanisms of viral transmission.\n\nOur results highlight the importance of mating strategy: bats species using swarming as mating strategy are less likely to be infected by Adenoviruses. Moreover, we found that locality of capture can explain a higher prevalence of Adenovirus within species. However, no general pattern has been found in the analysis at individual level, suggesting a strong species specificity and complex viral transmission dynamics.

ecology↗