Biology subjects

Micka, M.

Publications and source records attributed to Micka, M..

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↗

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↗

bioRxiv2025

Proximity interactomics identifies RAI14, EPHA2 and PHACTR4 as essential components of Wnt/planar cell polarity pathway in vertebrates

Wnt/planar cell polarity (Wnt/PCP) pathway is an evolutionarily conserved signaling cascade playing an inevitable role in cell biology. Deregulation of Wnt/PCP leads to severe developmental defects or cancer progression. Here, we applied proximity-dependent biotinylation (BioID) to capture the intracellular interactome of key Wnt/PCP components: transmembrane ROR1, ROR2 and VANGL2, and cytoplasmic DVL3 and PRICKLE1. Mapping of individual preys across the baits and subcellular compartments identified a group of 30 proteins that we tested by loss-of-function in zebrafish. Among those rai14, epha2 and phactr4 were essential for several Wnt/PCP-dependent processes such as zebrafish convergent extension, orientation of lateral organ cells, or migration of melanoma cells. Mechanistically, RAI14, EPHA2 and PHACTR4 connect the receptor complex to effector actomyosin. In summary, this study identified novel essential components of vertebrate WNT/PCP pathway and provides a detailed characterization of PCP complex composition that can serve as comprehensive resource for further analysis of Wnt/PCP function.

cell 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↗

bioRxiv2019

Comparative phosphorylation map of Dishevelled3 (DVL3)

In the presented study we analyze phosphorylation of human Dishevelled 3 (DVL3) induced by its previously reported (CK1{varepsilon}, NEK2, PLK1, CK2, RIPK4, PKC{delta}) and the newly identified (TTBK2, Aurora A) kinases. DVL3 contains 131 Ser/Thr whose phosphorylation generates complex barcodes underlying diverse DVL3 functions in Wnt pathways and other processes. We use quantitative mass spectrometry and via several complementary pipelines calculate site occupancies and quantify phosphorylation of >80 phosphorylated residues. In order to visualize the complex phosphorylation patterns, we design a novel visualization diagram, phosphoplot. Finally, we compare the individual sample and data processing approaches, identify their strengths and weaknesses. Subsequently, we verified a set of anti-phospho-DVL antibodies and were able to successfully confirm induction for several of the phosphorylation sites. From the biological point of view, our data represent an important reference point and a toolbox for further analysis of DVL functions and phosphorylation events that control them.\n\nOne sentence summaryThe study provides a comprehensive comparison of the phosphorylation of DVL3 induced by eight Ser/Thr kinases and identifies phosphorylation signatures associated with individual kinases.

cell biology↗