Biology subjects

Dogan, E.

Publications and source records attributed to Dogan, E..

5 recordsLinked to original sources

bioRxiv2025

Insulin-Like Growth Factor 1 Receptor Regulates Breast Cancer Cell Adhesion through Beta-1 Integrin

IntroductionThe insulin-like growth factor (IGF-1/IGF1R) pathway has been implicated in breast cancer aggressiveness; however, inhibition of this pathway has not been successful in clinical trials, indicating a lack of understanding about its role in TNBC metastasis. Recent studies have explored IGF1R involvement in integrin function and cancer cell adhesion dynamics. The goal of this study was to test the hypothesis that IGF1R itself regulates cancer cell adhesion. MethodsWe use MDA-MB-231 and Hs578T TNBC cell lines, siRNA-mediated knockdown, and adhesion assays to assess how IGF1R and integrin knockdowns impact cancer cell adhesion. Using xCELLigence E-plates, we quantify the effect of IGF-1 ligand stimulation versus IGF1R knockdown on functional cell adhesion. We also use HUVEC human endothelial cells to determine how IGF1R regulates adhesion to the endothelium. ResultsWe found that IGF-1 stimulation increased MDA-MB-231 TNBC adhesion, which was reversed by the IGF1R tyrosine kinase inhibitor BMS-754807 and the ligand-dependent receptor internalization inhibitor dansylcadaverine. Unexpectedly, IGF1R knockdown also potently stimulated cell adhesion. Concomitant {beta}1 integrin knockdown reversed the increased cell adhesion after both IGF-1 stimulation or IGF1R knockdown, indicating that the increased adhesion is {beta}1 integrin dependent. This was also seen via immunocytochemistry when cells were seeded on fibronectin. Finally, inhibiting IGF1R signaling also reduced MDA-MB-231 cell adhesion to HUVEC endothelial cells. DiscussionBoth IGF-1 stimulation and IGF1R knockdown in TNBC cells promote cell adhesion, which seems paradoxical. However, the commonality of both interventions is removal of IGF1R from the cell surface, since IGF-1 stimulation causes IGF1R internalization and intracellular trafficking. Blocking IGF1R signaling using a tyrosine kinase IGF1R inhibitor preserves IGF1R on the cell surface. Thus, we propose a model whereby surface-bound IGF1R inhibits {beta}1 integrin function and blocks cell adhesion. This model is supported further by our finding that treatment of MDA-MB-231 cells with dansylcadaverine, which inhibits ligand-mediated receptor internalization, blocked the effect of IGF-1 on adhesion. These findings may explain why selective IGF1R receptor antagonists, which downregulate IGF1R protein upon chronic administration, were unsuccessful in the clinical setting.

cancer biology↗

bioRxiv2025

Intergenerational Conditioning via Intermittent Parental Hypoxia Confers Stroke Resilience in Offspring

Background and AimsIntergenerational disease transmission, where parental exposures or experiences influence disease susceptibility in offspring, may represent a crucial layer of stroke risk that extends beyond genetics alone. Environmental conditioning, such as intermittent sub-lethal hypoxia, can induce adaptive protective stress responses in the brain. However, whether such parental conditioning enhances offspring resilience to cerebral ischaemia remains unclear. This study investigates whether intermittent hypoxia in parents acts as an intergenerational conditioning stimulus, conferring resilience to ischaemic stroke in offspring, and explores associated molecular mechanisms. MethodsMale and female Balb/C mice (F0) were exposed to intermittent hypoxia (8% O2, 2 hours every other day, 16 cycles) prior to mating. To confirm that intermittent hypoxia induced neuroprotection in the parental generation, a separate cohort of F0 mice underwent transient middle cerebral artery occlusion (tMCAO). Offspring (F1) were generated from hypoxia-exposed F0 breeders and divided into four groups: biparental hypoxia, paternal hypoxia, maternal hypoxia, and normoxic controls. Adult F1 offspring also underwent tMCAO to model ischaemic stroke. Infarct volume and brain swelling were assessed 48 hours post-ischaemia. In a subgroup of F1 offspring, tandem mass tag (TMT)-based proteomic analysis of injured brain tissue was performed post-stroke to identify molecular pathways associated with neuroprotection. ResultsParental intermittent hypoxia significantly reduced infarct size and swelling in F0 mice. These protective effects were inherited by F1 offspring, with biparental exposure producing the greatest reduction in infarct volume, followed by maternal-only and paternal-only groups, and exhibiting sex-specific differences. Proteomic profiling revealed distinct treatment and lineage clusters. Key pathways implicated in offspring neuroprotection included metabolic regulation, immune signalling, cytoskeletal organisation, and cell survival, notably involving PI3K-Akt and EGFR pathways. ConclusionsIntermittent hypoxia in parents acts as an intergenerational conditioning stimulus, conferring offspring resilience to ischaemic stroke. This neuroprotective phenotype is supported by coordinated molecular adaptations in key pathways involved in survival and stress response. These findings highlight the potential for parental environmental conditioning to shape stroke outcomes in offspring, opening new avenues for therapeutic exploration.

neuroscience↗

bioRxiv2024

In-host evolution of classic to convergent Klebsiella pneumoniae sequence type 147 isolates and impact of associated capsular changes on different morphotypes

Klebsiella pneumoniae, an important opportunistic pathogen, has long been categorized into two distinct pathotypes: the often multidrug-resistant classic (cKp) and the highly virulent hypervirulent (hvKp). However, a recent global trend has witnessed the emergence of convergent strains, seamlessly combining antimicrobial resistance with hypervirulence. Our study delved into a series of K. pneumoniae isolates sourced from the same patient, all belonging to the international, high-risk clonal lineage of sequence type 147. As reported in a previous study, these isolates exhibited diverse morphotypes on blood agar, ranging from small white to normal-sized white, grey, or grey and dry (g/d) colonies. Through an interplay of omics and phenotypic experiments, we unraveled the intricate mechanisms governing these distinct colony morphologies and their implications on bacterial virulence and resilience. While the earlier isolates demonstrated modest levels of resistance and virulence, their later counterparts showed significantly heightened levels, attributed to the acquisition of additional plasmids. Bioinformatics analysis unveiled a chromosomal insertion of a hybrid plasmid in one isolate, marking an unprecedented in-host microevolution from the classic to the convergent pathotype. All morphotypes exhibited positive insertion sequences around or within the K loci, with the grey or g/d phenotypes arising from impaired K loci. Despite lower serum resistance, these morphotypes demonstrated superior adhesion to human epithelial cells. Interestingly, while capsule-deficient strains are conventionally associated with decreased virulence, our isolates displayed high mortality rates in the Galleria mellonella infection model. In conclusion, our findings not only provide unprecedented insights into in-host microevolution within a patient, transitioning from the classic to the convergent pathotype, but also contribute significantly to the understanding of the diverse morphotypes exhibited by K. pneumoniae.

microbiology↗

bioRxiv2024

Klebsiella pneumoniae exhibiting a phenotypic hyper-splitting phenomenon including the formation of small colony variants

In this study, we characterized a Klebsiella pneumoniae strain in a patient with shrapnel hip injury, which resulted in multiple phenotypic changes, including the formation of a small colony variant (SCV) phenotype. Although already described since the 1960s, there is little knowledge about SCV phenotypes in Enterobacteriaceae. The formation of SCVs has been recognized as a bacterial strategy to evade host immune responses and compromise the efficacy of antimicrobial therapies, leading to persistent and recurrent courses of infections. In this case, 14 different, clonally identical resisto- and morpho-types were distinguished from the patients urine and tissue samples. Whole genome sequencing revealed the K. pneumoniae high-risk clonal lineage belonging to sequence type 147. Subculturing the SCV colonies consistently resulted in the reappearance of the initial SCV phenotype and three stable normal-sized phenotypes with distinct morphological characteristics. Additionally, an increase in resistance was observed over time in isolates that shared the same colony appearance. Our findings highlight the complexity of bacterial behavior by revealing a case of phenotypic "hyper-splitting" in a K. pneumoniae SCV and its potential clinical significance.

microbiology↗

bioRxiv2017

A Role For The F-Box Protein HAWAIIAN SKIRT In Plant miRNA Function

As regulators of gene expression in multicellular organisms, microRNAs (miRNAs) are crucial for growth and development. While a plethora of factors involved in their biogenesis and action in Arabidopsis thaliana have been described, these processes and their fine-tuning are not fully understood in plants. Here, we used plants expressing an artificial miRNA target mimic (MIM) to screen for negative regulators of miR156 activity. We identified a new mutant allele of the F-box protein HAWAIIAN SKIRT (HWS; At3G61590), hws-5, as a suppressor of the MIM156-induced developmental and molecular phenotypes. In hws plants, levels of endogenous miRNAs are increased and their mRNA targets decreased. Plants constitutively expressing full-length HWS - but not a truncated version lacking the F-box domain - display morphological and molecular phenotypes resembling those of mutants defective in miRNA biogenesis and activity. In combination with such mutants, hws loses its delayed floral organ abscission ( skirt) phenotype, suggesting epistasis. Also, the overall hws transcriptome profile partially resembles well-known miRNA mutants hyl1-2 and se-3, indicating action in a common pathway. We thus propose HWS as a novel, F-box dependent regulator of miRNA biogenesis.\n\nSummary statementHAWAIIAN SKIRT is a regulator of Arabidopsis thaliana microRNA biogenesis and acts in an F-box-dependent manner.

plant biology↗