Biology subjects

Paruch, K.

Publications and source records attributed to Paruch, K..

3 recordsLinked to original sources

bioRxiv2026

NOTCH1-specific phosphorylation of S1970 by Casein Kinase 1 is required for NOTCH1 transcriptional competence and signaling activity in vivo

The Notch and Wnt/{beta}-catenin signaling pathways are essential regulators for cell-fate decisions, cellular patterning, and tissue homeostasis. Multiple studies point to their orchestrated role during development, but the molecular mechanism of the protein-protein crosstalk is largely unknown. Here, after screening effects of Wnt/{beta}-catenin component loss on NOTCH1 protein, we identify Casein Kinase 1 (CK1) as a positive regulator of NOTCH1 activity in vitro and in vivo. We demonstrate that CK1 associates with NOTCH1 and that its kinase activity is required to sustain Notch-driven transcription. Using UltraID proximity-assay, we revealed that CK1 is required for the NOTCH1 interactivity with transporter proteins, and MAML1 both prior and after ligand-induced activation. Combining structural modelling, NMR, and mass spectrometry, we identified Serine 1970 (S1970) as a previously unreported residue within the Notch1 Intracellular Domain (N1ICD) essential for its signaling competence. Our modeling predicts that the phosphorylation of S1970 facilitates an intra-domain conformational switch with R1937 and R1962 residues altering the assembly of the N1ICD-MAML1-RBPJk transcriptional complex. Finally, we demonstrate the biological significance of N1ICD S1970 in vivo using Xenopus laevis axis-duplication rescue assay. Our results establish CK1 as a key positive mediator of the Notch receptor transcriptional activity.

cell biology↗

bioRxiv2025

Discovery of two structurally distinct classes of inhibitors targeting the nuclease MUS81 and enhancing efficacy of chemotherapy in cancer cells

Nucleases are emerging as promising pharmacological targets due to their essential role in maintaining genomic stability, which is crucial for cellular viability and can be exploited in the prevention and treatment of various diseases, including cancer. The conserved structure-specific endonuclease MUS81 is required for resolving branched DNA intermediates during replication, repair, and recombination. Aberrant activity of MUS81 leads to DNA damage, chromosomal abnormalities and genome instability, and contributes to oncogenesis. Pharmacological targeting of MUS81 thus represents an attractive underexplored therapeutic approach. Here we describe the discovery of two chemically distinct classes of small-molecule inhibitors of MUS81, exemplified by the compounds MU262 and MU876. Both compounds can effectively inhibit MUS81 in vitro and in the cell-based context and sensitize cancer cells to DNA-damaging agents through impairing their ability to repair DNA lesions. These compounds can be also used as chemical biology tools for further exploration of MUS81 function, and as leads in the process of drug discovery focused on development of new therapies that exploit DNA repair vulnerabilities in the treatment of cancer.

molecular biology↗

bioRxiv2022

Comparing the efficiency of six clearing methods in developing seeds of Arabidopsis thaliana

Tissue clearing methods eliminate the need for sectioning, thereby helping better understand the 3D organization of tissues and organs. In the past fifteen years, clearing methods have been developed to preserve endogenous fluorescent protein tags. Some of these methods (ClearSee, TDE, PEA-Clarity, etc.) were adapted to clear various plant species, with the focus on roots, leaves, shoot apical meristems, and floral parts. However, these methods have not been used in developing seeds beyond the early globular stage. Tissue clearing is problematic in post-globular seeds due to various apoplastic barriers and secondary metabolites. In this study, we compared six methods for their efficiency in clearing Arabidopsis thaliana seeds at post-globular embryonic stages. Three methods (TDE, ClearSee, and ClearSee alpha) have been already reported in plants whereas the others (fsDISCO, FAST9, and CHAPS clear) are used in this context for the first time. These methods were assessed for seed morphological changes, clearing capacity, removal of tannins, and spectral properties. We tested each method in seeds from globular to mature stages. The pros and cons of each method are listed herein. ClearSee alpha appears to be the method of choice as it preserves seed morphology and prevents tannin oxidation. However, FAST9 with 60% iohexol as a mounting medium is faster, clears better, and appears suitable for embryonic shape imaging. Our results may guide plant researchers to choose a suitable method for imaging fluorescent protein-labeled embryos in intact Arabidopsis seeds. Key messageClearSee alpha and FAST9 were optimized for imaging Arabidopsis seeds up to the torpedo stages. The methods preserve the fluorescence of reporter proteins and seed shape, allowing phenotyping embryos in intact seeds.

plant biology↗