Kovalchuk, Igor

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    Depletion of eukaryotic initiation factor 5B (eIF5B) reprograms the cellular transcriptome and leads to activation of endoplasmic reticulum (ER) stress and c-Jun N-terminal Kinase (JNK).
    (Springer, 2021) Bressler, Kamiko R.; Ross, Joseph A.; Ilnytskyy, Slava; Vanden Dungen, Keiran; Taylor, Katrina; Patel, Kush; Zovoilis, Athanasios; Kovalchuk, Igor; Thakor, Nehal
    During the integrated stress response (ISR), global translation initiation is attenuated; however, noncanonical mechanisms allow for the continued translation of specific transcripts. Eukaryotic initiation factor 5B (eIF5B) has been shown to play a critical role in canonical translation as well as in noncanonical mechanisms involving internal ribosome entry site (IRES) and upstream open reading frame (uORF) elements. The uORF-mediated translation regulation of activating transcription factor 4 (ATF4) mRNA plays a pivotal role in the cellular ISR. Our recent study confirmed that eIF5B depletion removes uORF2-mediated repression of ATF4 translation, which results in the upregulation of growth arrest and DNA damage-inducible protein 34 (GADD34) transcription. Accordingly, we hypothesized that eIF5B depletion may reprogram the transcriptome profile of the cell. Here, we employed genome-wide transcriptional analysis on eIF5B-depleted cells. Further, we validate the up- and downregulation of several transcripts from our RNA-seq data using RT-qPCR. We identified upregulated pathways including cellular response to endoplasmic reticulum (ER) stress, and mucin-type O-glycan biosynthesis, as well as downregulated pathways of transcriptional misregulation in cancer and T cell receptor signaling. We also confirm that depletion of eIF5B leads to activation of the c-Jun N-terminal kinase (JNK) arm of the mitogen-activated protein kinase (MAPK) pathway. This data suggests that depletion of eIF5B reprograms the cellular transcriptome and influences critical cellular processes such as ER stress and ISR.
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    Environmental intervention as a therapy for adverse programming by ancestral stress
    (Nature Research, 2016) McCreary, J. Keiko; Erickson, Zachary T.; Hao, XongXin; Ilnytskyy, Yaroslav; Kovalchuk, Igor; Metz, Gerlinde A. S.
    Ancestral stress can program stress sensitivity and health trajectories across multiple generations. While ancestral stress is uncontrollable to the filial generations, it is critical to identify therapies that overcome transgenerational programming. Here we report that prenatal stress in rats generates a transgenerationally heritable endocrine and epigenetic footprint and elevated stress sensitivity which can be alleviated by beneficial experiences in later life. Ancestral stress led to downregulated glucocorticoid receptor and prefrontal cortex neuronal densities along with precocious development of anxiety-like behaviours. Environmental enrichment (EE) during adolescence mitigated endocrine and neuronal markers of stress and improved miR-182 expression linked to brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) regulation in stressed lineages. Thus, EE may serve as a powerful intervention for adverse transgenerational programming through microRNA-mediated regulation of BDNF and NT-3 pathways. The identification of microRNAs that mediate the actions of EE highlights new therapeutic strategies for mental health conditions and psychiatric disease.
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    Non-coding RNAs match the deleted genomic regions in humans
    (Nature Research, 2016) Byeon, Boseon; Kovalchuk, Igor
    RNA is transcribed from DNA, and therefore, there should be no RNA transcript from the deleted DNA region. Our study attempted to analyse whether any RNA cache that maps the deleted regions is present in human cells. Using data from the 1000 genome project, we selected 41 CEPH (CEU) and 38 Yoruba (YRI) samples that included the data for the entire genome sequence and ncRNA and mRNA sequences. Aligning the ncRNA reads against the genomic DNA in individual samples has revealed that 229 out of 1114 homozygous deletions have ncRNA reads that map to them. Further analysis has revealed that ncRNA reads that map the deleted regions are enriched around the deletion ends and at genic regions of the genome. The read enrichment at deletion ends suggests that these ncRNAs are likely some form of double-strand break induced RNAs. Our analysis suggests that human cells may contain a residual ncRNA cache that is possibly propagated across generations.
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    Evidence for ancestral programming of resilience in a two-hit stress model
    (Frontiers Media, 2017) Faraji, Jamshid; Soltanpour, Nabiollah; Ambeskovic, Mirela; Zucchi, Fabiola C. R.; Beaumier, Pierre; Kovalchuk, Igor; Metz, Gerlinde A. S.
    In a continuously stressful environment, the effects of recurrent prenatal stress (PS) may accumulate across generations and alter stress vulnerability and resilience. Here, we report in female rats that a family history of recurrent ancestral PS facilitates certain aspects of movement performance, and that these benefits are abolished by the experience of a second hit, induced by a silent ischemia during adulthood. Female F4-generation rats with and without a family history of cumulative multigenerational PS (MPS) were tested for skilled motor function before and after the induction of a minor ischemic insult by endothelin-1 infusion into the primary motor cortex. MPS resulted in improved skilled motor abilities and blunted hypothalamic-pituitary-adrenal (HPA) axis function compared to non-stressed rats. Deep sequencing revealed downregulation of miR-708 in MPS rats along with upregulation of its predicted target genes Mapk10 and Rasd2. Through miR-708 stress may regulate mitogen-activated protein kinase (MAPK) pathway activity. Hair trace elemental analysis revealed an increased Na/K ratio, which suggests a chronic shift in adrenal gland function. The ischemic lesion activated the HPA axis in MPS rats only; the lesion, however, abolished the advantage of MPS in skilled reaching. The findings indicate that MPS generates adaptive flexibility in movement, which is challenged by a second stressor, such as a neuropathological condition. Thus, a second “hit” by a stressor may limit behavioral flexibility and neural plasticity associated with ancestral stress.
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    The stimulatory effect of CaCl2, NaCl and NH4NO3 salts on the ssDNA-binding activity of RecA depends on nucleotide cofactor and buffer pH
    (Korean Society for Biochemistry and Molecular Biology, 2011) Ziemienowicz, Alicja; Seyed Mohammad, Reza Rahavi; Kovalchuk, Igor
    The single-stranded DNA binding activity of the Escherichia coli RecA protein is crucial for homologous recombination to occur. This and other biochemical activities of ssDNA binding proteins may be affected by various factors. In this study, we analyzed the effect of CaCl2, NaCl and NH4NO3 salts in combination with the pH and nucleotide cofactor effect on the ssDNA-binding activity of RecA. The studies revealed that, in addition to the inhibitory effect, these salts exert also a stimulatory effect on RecA. These effects occur only under very strict conditions, and the presence or absence and the type of nucleotide cofactor play here a major role. It was observed that in contrast to ATP, ATPγS prevented the inhibitory effect of NaCl and NH4NO3, even at very high salt concentration. These results indicate that ATPγS most likely stabilizes the structure of RecA required for DNA binding, making it resistant to high salt concentrations.