Predictive Potential of RNA Polymerase B (II) Subunit 1 (RPB1) Cytoplasmic Aggregation for Neoadjuvant Chemotherapy Failure

Stress-Induced Changes in Nucleocytoplasmic Localization of Crucial Factors in Gene Expression Regulation

This study investigates the toxic effect of harmful materials, unfiltered by the placenta, on neonatal umbilical cord (UC) vessels, focusing on stress-induced adaptations in transcriptional and translational processes. It aims to analyze changes in pathways related to mRNA condensate formation, transcriptional regulation, and DNA damage response under maternal smoking-induced stress. UC vessels from neonates born to smoking (Sm) and nonsmoking mothers (Ctr) were examined. Immunofluorescence staining and confocal microscopy assessed the localization of key markers, including Transcription Complex Subunit 1 (CNOT1) and the largest subunit of RNA polymerase II enzyme (RPB1). Additionally, markers of DNA damage response, such as Poly(ADP-ribose) polymerase-1, were evaluated. In Sm samples, dissolution of CNOT1 granules in UC vessels was observed, potentially aiding stalled translation and enhancing transcription via RPB1 assembly and translocation. Control vessels showed predominant cytoplasmic RPB1 localization. Despite adaptive responses, Sm endothelial cells exhibited significant damage, indicated by markers like Poly(ADP-ribose) polymerase-1. Ex vivo metal treatment on control vessels mirrored Sm sample alterations, emphasizing marker roles in cell survival under toxic exposure. Maternal smoking induces specific molecular adaptations in UC vessels, affecting mRNA condensate formation, transcriptional regulation, and DNA damage response pathways. Understanding these intricate molecular mechanisms could inform interventions to improve neonatal health outcomes and mitigate adverse effects of toxic exposure during pregnancy.

1,6-Hexanediol Is Inducing Homologous Recombination by Releasing BLM from Assemblysomes in Drosophila melanogaster

We recently demonstrated that 1,6-hexanediol inhibits the formation of assemblysomes. These membraneless cell organelles have important roles in co-translational protein complex assembly and also store halfway translated DNA damage response proteins for a timely stress response. Recognizing the therapeutic potential of 1,6-hexanediol in dismantling assemblysomes likely to be involved in chemo- or radiotherapy resistance of tumor cells, we initiated an investigation into the properties of 1,6-hexanediol. Our particular interest was to determine if this compound induces DNA double-strand breaks by releasing the BLM helicase. Its yeast ortholog Sgs1 was confirmed to be a component of assemblysomes. The BLM helicase induces DNA damage when overexpressed due to the DNA double-strand breaks it generates during its normal function to repair DNA damage sites. It is evident that storing Sgs1 helicase in assemblysomes is crucial to express the full-length functional protein only in the event of DNA damage. Alternatively, if we dissolve assemblysomes using 1,6-hexanediol, ribosome-nascent chain complexes might become targets of ribosome quality control. We explored these possibilities and found, through the Drosophila wing-spot test assay, that 1,6-hexanediol induces DNA double-strand breaks. Lethality connected to recombination events following 1,6-hexanediol treatment can be mitigated by inducing DNA double-strand breaks with X-ray. Additionally, we confirmed that SMC5 recruits DmBLM to DNA damage sites, as knocking it down abolishes the rescue effect of DNA double-strand breaks on 1,6-hexanediol-induced lethality in Drosophila melanogaster.