Biology subjects

Zdrahal, Z.

Publications and source records attributed to Zdrahal, Z..

22 records · Page 2Linked to original sources

bioRxiv2020

Laser capture microdissection in combination with mass spectrometry: Approach to characterization of tissue-specific proteomes of Eudiplozoon nipponicum (Monogenea, Polyopisthocotylea)

Eudiplozoon nipponicum (Goto, 1891) is a hematophagous monogenean ectoparasite which inhabits the gills of the common carp (Cyprinus carpio). Heavy infestation can lead to anemia and in conjunction with secondary bacterial infections cause poor health and eventual death of the host. This study is based on an innovative approach to protein localization which has never been used in parasitology before. Using laser capture microdissection, we dissected particular areas of the parasite body without contaminating the samples by surrounding tissue, and in combination with analysis by mass spectrometry obtained tissue-specific proteomes of tegument, intestine, and parenchyma of our model organism, E. nipponicum. We successfully verified the presence of certain functional proteins (e.g. cathepsin L) in tissues where their presence was expected (intestine) and confirmed that there were no traces of these proteins in other tissues (tegument and parenchyma). Additionally, we identified a total of 2,059 proteins, including 72 peptidases and 33 peptidase inhibitors. As expected, the greatest variety was found in the intestine and the lowest variety in the parenchyma. Our results are significant on two levels. Firstly, we demonstrated how one can localize all proteins in one analysis and without using laboratory animals (antibodies for immunolocalization of single proteins). Secondly, this study offers the first complex proteomic data on not only the E. nipponicum but within the whole class of Monogenea, which was from this point of view until recently neglected.

biochemistry↗

bioRxiv2019

RNF43 truncating mutations mediate a tumour suppressor-to-oncogene switch to drive niche-independent self-renewal in cancer

Wnt/{beta}-catenin signalling is a primary pathway for stem cell maintenance during tissue renewal and a frequent target for mutations in cancer. Impaired Wnt receptor endocytosis due to loss of the ubiquitin ligase RNF43 gives rise to Wnt-hypersensitive tumours that are susceptible to anti-Wnt-based therapy. Contrary to this paradigm, we identify a class of RNF43 truncating cancer mutations that strongly induce {beta}-catenin-mediated transcription, despite exhibiting retained Wnt receptor downregulating activity. Mechanistically, these RNF43 mutants trap Casein Kinase (CK)1 at the plasma membrane, which prevents {beta}-catenin turnover and propels ligand-independent Wnt target gene transcription. When introduced in human colon stem cells, these oncogenic RNF43 mutants cooperate with p53 loss to drive a niche-independent program for self-renewal and proliferation. Importantly, onco-RNF43 mutations, unlike conventional LOF RNF43 mutations, confer resistance to anti-Wnt-based therapy. Our data demonstrate the relevance of studying patient-derived mutations for understanding disease mechanisms and improved applications of precision medicine.

cancer biology↗

bioRxiv2019

Phosphorylation of multiple proteins involved in ciliogenesis by Tau Tubulin kinase 2

Primary cilia (PC) are organelles necessary for proper implementation of developmental and homeostasis processes. To initiate their assembly, coordinated actions of multiple proteins are needed. Tau tubulin kinase 2 (TTBK2) is a key player in the cilium assembly pathway, controlling final step of cilia initiation. The function of TTBK2 in ciliogenesisis is critically dependent on its kinase activity, however, precise mechanism of TTBK2 action is so far incompletely understood, due to very limited information about its relevant substrates. In this study we identify CEP83, CEP89, CCDC92, Rabin8 and DVL3 as substrates of TTBK2 kinase activity. Further, we characterise a set of phosphosites of the newly identified substrates and CEP164, induced by TTBK2 in vitro and in vivo. Intriguingly, we further show that identified TTBK2 phosphosites and consensus sequence delineated from those are distinct from motifs previously assigned to TTBK2. Finally, we address functional relevance of selected phosphorylations of CEP164 and provide evidence that the examined TTBK2-induced phosphorylations of CEP164 are relevant for the process of cilia formation. In summary, our work provides important insight into substrates-TTBK2 kinase relationship and suggests that phosphorylation of substrates on multiple sites by TTBK2 is probably involved in the control of ciliogenesis in human cells.

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↗