Biology subjects

Sedo, O.

Publications and source records attributed to Sedo, O..

5 recordsLinked to original sources

bioRxiv2026

Molecular mechanisms behind the functional (non)redundancy of CK1 paralogs in the Wnt pathway

The casein kinase 1 (CK1) family of serine/threonine protein kinases consists of seven isoforms in humans. CK1 family members are important regulators of the Wnt/{beta}-catenin signaling pathway. Using a comprehensive panel of CRISPR/Cas9-generated knockout cell lines, we demonstrated the opposing roles of endogenous CK1 (negative, via phosphorylation of {beta}-catenin in the destruction complex) and CK1{delta}/{epsilon} (positive, via phosphorylation of DVL in the signalosome), while no phenotype was observed for CK1{gamma}1/2/3 triple knockout cells. Using in vitro kinase assays and TurboID-based interactomics, we revealed that this functional divergence between CK1 and CK1{epsilon} is not due to the intrinsically different capacity to phosphorylate {beta}-catenin or DVL but rather due to different affinities for the destruction complex and signalosome in the cellular environment. Through functional analysis of CK1-CK1{epsilon} chimeras containing both N-terminal and C-terminal domain swaps, we identified the N-terminal lobe of CK1 and the C-terminus of CK1{epsilon} as determinants mediating increased affinity towards the degradasome and signalosome, respectively. We further show that the CK1 N-lobe not only drives cellular activity toward {beta}-catenin but also underlies the CK1-specific interaction with the scaffolding protein SACK1G (also known as FAM83G and PAWS1). Additionally, despite clearly distinct physiological roles of CK1 and CK1{delta}/{epsilon}, we provide evidence that, in the absence of CK1, CK1{delta} and CK1{epsilon} can physically and functionally substitute for CK1 in the {beta}-catenin destruction complex. This rewires CK1{delta} and CK1{epsilon} as negative regulators acting via phosphorylation of {beta}-catenin in the destruction complex. These findings resolve prior contradictions by (i) clarifying context-dependent CK1 roles, (ii) identifying mechanistic determinants navigating CK1 and CK1{epsilon} to different substrates, and (iii) defining the limitations of these affinity-based subcellular distributions that become apparent especially in the physical absence of the physiological, high-affinity kinase. An important implication of our findings is the identification of a mechanism that changes the ultimate outcome of CK1{delta}/{epsilon} inhibitor treatment from Wnt/{beta}-catenin pathway inhibition to its robust activation.

cell biology↗

bioRxiv2026

Enhanced RNA Formation Under Amine-Rich Local Atmospheres from 2',3'- Cyclic Nucleotides

The core biopolymers (DNA, RNA and proteins) are assembled from their monomers under conditions that avoid water. RNA is crucial for the Origin of Life. When cleaved from its polymerized state, RNA first transitions to nucleoside 2,3-cyclic phosphates. In the reverse direction, RNA polymerizes from 2,3-cyclic monomers in dry states, creating short oligomers that then can ligate on a template under aqueous, alkaline conditions. We studied the role of the counterions in polymerization of 2,3-cyclic nucleotides under geologically plausible settings. Through experiments and simulations, we demonstrate that the presence of ammonium and alkylammonium counterions greatly improves RNA polymerization. The otherwise less reactive cytidine containing monomers formed polyC sequences of up to heptamers; copolymers of AU, GC, or GCAU were detected up to hexamers. Our findings suggest three reasons for this: (1) (Alkyl)ammonium cations form hydrogen bonds with phosphates, (2) their alkaline pKa value can trigger general base catalysis, and (3) (alkyl)ammonium salts naturally form dry, anhydrous materials. The findings indicate that pyrolyzed organic tars creating ammonia-rich gas pockets in subsurface rocks could have enhanced the early evolution of RNA. TOC image O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/713775v1_ufig1.gif" ALT="Figure 1"> View larger version (112K): org.highwire.dtl.DTLVardef@1adc431org.highwire.dtl.DTLVardef@12b8da0org.highwire.dtl.DTLVardef@5f187dorg.highwire.dtl.DTLVardef@140ed1a_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2025

A Wnt-induced conformational phospho-switch in DVL3 controls interaction with Frizzled receptors and Wnt/β-catenin signaling

When Wnt ligands bind to Frizzled (FZD) receptors, Dishevelled protein (DVL) gets multiphosphorylated by Casein kinase 1 (CK1). Although, it is well known that DVL phosphorylation relays Wnt signals from receptors to downstream effectors, any mechanistic aspects of DVL function related to phosphorylation remain unresolved. Here, we uncovered a Wnt-induced DVL phospho-switch which is mutually exclusive with FZD engagement. CK1 multiphosphorylation changes dramatically the bulk electrostatics to promote DVL intramolecular coupling between the DEP domain and the adjacent disordered region. A panel of phospho-switch mutants demonstrated a switch-like coupling at the molecular level when a charge threshold is reached. Charge accumulation proximal to DEP proved to be a key functional event required, but not sufficient, for Wnt/{beta}-catenin signaling. Interestingly, the charge-dependent switch-like character of DVL controlled its association with FZD. By integrating findings at different levels, we propose a universal mechanism in which Wnt-induced DVL conformational phospho-switch outcompetes FZD binding and triggers DVL detachment from FZD.

molecular biology↗

bioRxiv2023

A new mechanism of posttranslational polyglutamylation regulates phase separation and signaling of the Wnt pathway protein Dishevelled.

Polyglutamylation is a reversible post-translational modification that is catalyzed by enzymes from the tubulin tyrosine ligase-like (TTLL) family. Here, we found that TTLL11 generates a previously unknown type of polyglutamylation initiated by the addition of a glutamate residue to the free C-terminal carboxyl group of a substrate protein. TTLL11 efficiently polyglutamylates the Wnt signaling protein Disheveled 3 (DVL3), thereby changing the interactome of DVL3, as well as it increases its capacity to get phosphorylated, to undergo liquid-liquid phase separation (LLPS), and to act in the non-canonical Wnt pathway. Both carboxyterminal polyglutamylation and the resulting reduction in LLPS capacity of DVL3 were reverted by the deglutamylating enzyme CCP6, which demonstrates the causal relationship between TTLL11-mediated polyglutamylation and LLPS. We thus discovered a novel type of posttranslational modification, which significantly broadens the range of proteins that can be modified by polyglutamylation and provides the first evidence that polyglutamylation can act as a regulator of protein LLPS.

cell biology↗

bioRxiv2020

Primitive RNA-catalysis with guanine-rich oligonucleotide sequences - the case of a (GGC)3 nonamer

A cornerstone of molecular evolution leading to the emergence of life on our planet is associated with appearance of the first catalytic RNA molecules. A question remains regarding the nature of the simplest catalytic centers that could mediate the chemistry needed for RNA-catalysis. In the current paper we provide a new example supporting our previously suggested model proposing that transiently formed open loop geometries could serve as temporary catalytic sites in the most ancient short oligonucleotides. In particular, using two independent detection techniques, PAGE and MALDI-ToF analysis, we show that prolonged thermal treatment of a 5-phosphorylated (GGC)3 sequence at weakly acidic or neutral pH in the presence of tris(hydroxymethyl)aminomethane, produces a species characterized by a (GGC)3G stoichiometry, which is compatible with the cleavage-terminal recombination chemistry suggested in our previous studies. Our new findings are complemented by microsecond-scale molecular dynamics simulations, showing that (GGC)3 dimers readily sample transient potentially catalytic geometries compatible with the experimentally observed terminal recombination chemistry.

biochemistry↗