Biology subjects

Jelinek, J.

Publications and source records attributed to Jelinek, J..

6 recordsLinked to original sources

bioRxiv2023

Hearing loss in juvenile rats leads to excessive play fighting and hyperactivity, mild cognitive deficits and altered neuronal activity in the prefrontal cortex

BackgroundIn children, hearing loss has been associated with hyperactivity, disturbed social interaction, and risk of cognitive disturbances. Mechanistic explanations of these relations sometimes involve language. To investigate the effect of hearing loss on behavioral deficits in the absence of language, we tested the impact of hearing loss in juvenile rats on motor, social, and cognitive behavior and on physiology of prefrontal cortex. MethodsHearing loss was induced in juvenile (postnatal day 14) male Sprague-Dawley rats by intracochlear injection of neomycin under general anaesthesia. Sham-operated and non-operated hearing rats served as controls. One week after surgery auditory brainstem response (ABR) measurements verified hearing loss or intact hearing in sham-operated and non-operated controls. All rats were then tested for locomotor activity (open field), coordination (Rotarod), and for social interaction during development in weeks 1, 2, 4, 8, 16, and 24 after surgery. From week 8 on, rats were trained and tested for spatial learning and memory (4-arm baited 8-arm radial maze test). In a final setting, neuronal activity was recorded in the medial prefrontal cortex (mPFC). ResultsIn the open field deafened rats moved faster and covered more distance than sham-operated and non-operated controls from week 8 on (both p<0.05). Deafened rats showed significantly more play fighting during development (p<0.05), whereas other aspects of social interaction, such as following, were not affected. Learning of the radial maze test was not impaired in deafened rats (p>0.05), but rats used less next-arm entries than other groups indicating impaired concept learning (p<0.05). In the mPFC neuronal firing rate was reduced and enhanced irregular firing was observed. Moreover, oscillatory activity was altered, both within the mPFC and in coherence of mPFC with the somatosensory cortex (p<0.05). ConclusionsHearing loss in juvenile rats leads to hyperactive behavior and pronounced play-fighting during development, suggesting a causal relationship between hearing loss and cognitive development. Altered neuronal activities in the mPFC after hearing loss support such effects on neuronal networks outside the central auditory system. This animal model provides evidence of developmental consequences of juvenile hearing loss on prefrontal cortex in absence of language as potential confounding factor.

animal behavior and cognition↗

bioRxiv2023

eIF3e and eIF3d control expression of riboproteins and key components of the MAPK signaling pathway.

Protein synthesis plays a major role in homeostasis and when dysregulated leads to various pathologies including cancer. To this end, imbalanced expression of eukaryotic translation initiation factors (eIFs) is not only a consequence but also a driver of neoplastic growth. eIF3 is the largest, multi-subunit translation initiation complex with a modular assembly, where aberrant expression of one subunit generates only partially functional subcomplexes. To comprehensively study the effects of eIF3 remodeling, we contrasted the impact of eIF3d, eIF3e or eIF3h depletion on the translatome of HeLa cells using Ribo-seq. Depletion of eIF3d or eIF3e, but not eIF3h reduced the levels of multiple components of the MAPK signaling pathways. Surprisingly, however, depletion of all three eIF3 subunits increased MAPK/ERK pathway activity. Depletion of eIF3e and partially eIF3d also increased translation of TOP mRNAs that encode mainly ribosomal proteins and other components of the translational machinery. Moreover, alterations in eIF3 subunit stoichiometry were often associated with changes in translation of mRNAs containing short uORFs, as in the case of the proto-oncogene MDM2 and the transcription factor ATF4. Collectively, perturbations in eIF3 subunit stoichiometry exert specific effect on the translatome comprising signaling and stress-related transcripts with complex 5 UTRs that are implicated in homeostatic adaptation to stress and cancer.

molecular biology↗

bioRxiv2021

Ultraviolet radiation modulates DNA methylation in melanocytes

Ultraviolet radiation (UVR) is the principal causal factor for melanoma; albeit the underlying mechanisms remain unclear. While the mutagenic properties of UVR are irrefutable, the role of UVR-induced mutations in the initiation of melanoma is controversial which highlights the gap in our knowledge of the initial critical molecular mechanisms of UVR-induced melanomagenesis. To investigate the potential non-mutational mechanisms of UVR-induced melanomagenesis, we studied the role of UVR in modulating DNA methylation changes in melanocytes via next-generation sequencing-based methodologies. Here we show that UVR directly causes stable changes in the DNA methylome and transcriptome, one month after exposure. Genomic features associated with transcription were protected from 5mC alterations whereas CpG sites found in intergenic regions were more likely to be affected. Additionally, the long-term effects of UVR seem to perturb signaling pathways important for melanocyte biology. Interestingly, UVR-sensitive CpG sites were found to be prognostic of overall patient survival and highlighted a subset of CpG sites that may be relevant in melanomagenesis. SignificanceWe report a novel finding that ultraviolet radiation (UVR) induces DNA methylation changes along with stable alterations in gene expression in cultured melanocytes. Our results provide experimental evidence of UVR-induced epigenetic rewiring, which may be implicated in the susceptibility to melanomagenesis, independently of its mutational effects. These findings offer novel insight into the role of UVR in the initiation and pathogenesis of melanoma via a currently underappreciated mechanism.

cancer biology↗

bioRxiv2021

Single cell transcriptomic analysis reveals cellular diversity of murine esophageal epithelium and age-associated mitochondrial dysfunction

Stratified squamous epithelium of the esophagus is comprised of basal keratinocytes that execute a terminal differentiation program in overlying suprabasal and superficial cell layers. Although morphologic progression coupled with expression of specific molecular markers has been characterized along the esophageal epithelial differentiation gradient, the molecular heterogeneity within the cell types along this trajectory has yet to be classified at the level of single cell resolution. To explore the molecular characteristics of esophageal keratinocytes along the squamous differentiation continuum, we performed single cell RNA-Sequencing transcriptomic profiling of 7,972 cells from murine esophageal epithelial sheets. We identified 8 distinct cell clusters in esophageal epithelium, unveiling an unexpected level of diversity, particularly among basal cells. We further mapped the cellular pathways and lineage trajectories within basal, suprabasal, and superficial clusters as well as within the heterogeneous basal cell populations, providing a comprehensive molecular view of esophageal epithelial cells in the context of squamous differentiation. Finally, we explored the impact of tissue aging upon esophageal epithelial cell clusters and demonstrated that mitochondrial dysfunction is a feature of aging in normal esophageal epithelium. These studies provide an unparalleled molecular perspective on murine esophageal keratinocytes that will serve as a valuable resource for dissecting cell type-specific roles in esophageal biology under conditions of homeostasis, aging, and tissue pathology.

molecular biology↗

bioRxiv2020

Microbiota Accelerates Age-Related CpG island Methylation in Colonic Mucosa

DNA methylation is an epigenetic mark that is altered in cancer and aging tissues. The effects of extrinsic factors on DNA methylation remain incompletely understood. Microbial dysbiosis is a hallmark of colorectal cancer, and infections have been linked to aberrant DNA methylation in cancers of the GI tract. To determine the microbiotas impact on DNA methylation, we studied the methylomes of colorectal mucosa in germ-free (no microbiota) and specific-pathogen-free (controlled microbiota) mice, as well as in Il-10 KO mice (Il10-/-) which are prone to inflammation and tumorigenesis in the presence of microbiota. The presence of microbiota was associated with changes in 5% of the methylome and Il10-/- mice showed alterations in 4.1% of the methylome. These changes were slightly more often hypo than hypermethylation and affected preferentially CpG sites located in gene bodies and intergenic regions. Mice with both Il-10 KO and microbiota showed much more pronounced alterations, affecting 18% of the methylome. When looking specifically at CpG island methylation alterations, a hallmark of aging and cancer, 0.4% were changed by the microbiota, 0.4% were changed by Il10-/-, while 4% were changed by both simultaneously. These effects are comparable to what is typically seen when comparing colon cancer to normal. We next compared these methylation changes to those seen in aging, and after exposure to the colon carcinogen Azoxymethane (AOM). Aging was associated with alterations in 18% of the methylome, and aging changes were accelerated in the Il10-/- /SPF mice. By contrast, AOM induced profound hypomethylation that was distinct from the effects of aging or of the microbiota. CpG sites modified by the microbiota were over-represented among DNA methylation changes in colorectal cancer. Thus, the microbiota affects the DNA methylome of colorectal mucosa in patterns reminiscent of what is observed in aging and in colorectal cancer.

microbiology↗

bioRxiv2019

TET1 and TDG suppress intestinal tumorigenesis by down regulating the inflammatory and immune response pathways

IntroductionAberrant DNA methylation is frequently observed in colorectal cancer (CRC), but the underlying mechanisms are poorly understood. Ten-Eleven Translocation (TET) dioxygenases and DNA repair enzyme Thymine DNA Glycosylase (TDG) are involved in active DNA demethylation by generating and removing, respectively, novel oxidized cytosine species. Mutations of TET1 and TDG, and alterations of the levels of oxidized cytosine species have been identified in human CRC cases, but the biological significance of the TET-TDG demethylation axis in intestinal tumorigenesis is unclear.\n\nMaterial and MethodsWe generated ApcMin mice with additional inactivation of Tet1 and/or Tdg, and characterized the methylome and transcriptome of intestinal adenomas by DREAM and RNA sequencing, respectively.\n\nResultsTet1- and/or Tdg-deficient ApcMin mice show enhanced intestinal tumorigenesis in comparison to wild type Tet1 and Tdg ApcMin mice. Specifically, Tet1 and/or Tdg-deficient ApcMin adenomas manifested increased size or features of erosion and stroma activation. Methylome analysis revealed progressive loss of global DNA hypomethylation in colonic adenomas from Tet1- and Tdg-deficient ApcMin mice, and hypermethylation of CpG islands in Tet1-deficient ApcMin mice. In addition, RNA sequencing showed upregulation of genes in inflammatory and immune response pathways in Tet1-and Tdg-mutant colonic adenomas compared to control ApcMin adenomas.\n\nConclusionsTaken together, these findings demonstrate the important role of active DNA demethylation mediated by TET-TDG in reducing intestinal tumor formation, by modulating the epigenome and inflammatory/immune responses. This study highlights a novel mechanism of epigenetic deregulation during intestinal tumorigenesis with diagnostic, therapeutic and prognostic implications.

cancer biology↗