Harnos Lab - Section of Animal Physiology and Immunology

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What we work with
We study early Xenopus frog embryos: a powerful model for developmental biology. 🐸

Why frogs
Their embryos are large, develop outside the body, and are ideal for live imaging and experimental manipulation. 🔬

Why Xenopus
Xenopus was the first reliable model used for human fertility testing (the Hogben test) and later became the most widely used amphibian model in biomedical research. 🧪

What we study
Neural tube formation, neural crest cell migration, and the signaling mechanisms that shape developing tissues.
And more. 🧠

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Want to discover more? Click the link to our short reportages on Czech Radio or Czech TV broadcasts (both in Czech), and the popular biology blog, The Node (in English).

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PRINCIPAL INVESTIGATOR

Group leader: Assist. Prof. Jakub Harnos, Ph.D.

Office: Campus Bohunice, bldg. D36, rm 1S16

E-mail: harnos@sci.muni.cz

Telephone: +420 549 49 4465

ORCID ID: 0000-0002-0752-9260

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Scientific autobiography

My research explores how cells signal, move, and organize tissues during development.
After PhD training in Germany and postdoctoral work in New York on WNT/PCP signaling in Xenopus, I now run an independent lab at Masaryk University.

We use live embryos, advanced imaging, and molecular tools to address fundamental questions in developmental and disease biology.

🧬 Field: cellular signaling

🇨🇿/🇩🇪 PhD: Brno/Wurzburg (molecular signaling)
🇺🇸 Postdoc: New York (Xenopus, PCP)
🇨🇿 PI: Masaryk University since 2020 (Xenopus)

🔬 Approach: live imaging, biosensors, proteomics, Xenopus

Fellowships, Grants, and Awards

*2026 – 2028: MUNI Junior Star (#MUNI/JS/1952/2025), Grant Agency of Masaryk University, Czechia

*2025 – 2026: MSCAfellow5_MUNI (#22_010/0003229), Czech MEYS, Czechia

*2024 – 2026: Grant in the Standard/Senior category (#24-10622S), Czech Science Foundation, Czechia

2023: Hemsley Fellowship (#203103), Xenopus course, Cold Spring Harbor Laboratories, NY, USA _{^{(declined due to family reasons)}}

2022 – 2024: Grant in the Standard/Senior category (#22-06405S), Czech Science Foundation, Czechia

2022 – 2024: Science & Humanities Award Junior (#MUNI/J/0004/2021), Grant Agency of Masaryk University, Czechia

2020: “Seal of Excellence” in MSCA-IF-2020 (#101028952), European Commission, Brussels

2018 – 2019: “Excellent Results” Grant (#MUNI/E/0533/2018), Grant Agency of Masaryk University, Czechia

2017 – 2017: EMBO Short-term Fellowship (#ASTF 687-2016), University of Wurzburg, Germany

2016 – 2016: Mobility program “Free mover”, University of Wurzburg, Germany

*Current funding

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Cells need to know where they are and where to go.
We study planar cell polarity (PCP) — the way cells align and coordinate their behavior across a tissue.

Polarity is usually seen as a simple directional guide. We think it does much more.
Our research shows that polarity proteins can actively start major developmental events, such as neural tube formation, an early step in building the brain and spinal cord.

We are also interested in cell movement. Cells need extra energy to move, but what tells them to start producing it?
We propose that cell polarity works like a switch, turning on the energy and structural changes needed for migration.

In short: we study how polarity proteins actively drive cell behavior, using Xenopus embryos and cell models to watch these processes in real time.

LEFT: A developing Xenopus tadpole, whose neural cells have been marked with the green fluorescent protein (GFP).

RIGHT: We investigate cellular processes in which proteins can initiate several subsequent events that we can observe using microscopes.

In the picture, there are two cells expressing green fluorescent protein fused to a protein of our interest. The last picture on the right shows that the green fusion protein co-localizes with the red cellular process, suggesting that protein X induces this particular cellular process Y (images were edited in Imaris software v9.8).

Keywords

Planar polarity, neural tube formation, cell migration, bioenergetics, tissue culture cells, Xenopus embryos.

OUR SCIENTIFIC PAPERS

Cellular signaling in vertebrates (planar cell polarity signaling):
- Radaszkiewicz KA, Radaszkiewicz TW, Kolářová P, Paclíková P, Gömöryová K, Novotná Š, Maia LA, Číhalová T, Le Y, Bárta T, Hanáková K, Hýsková A, Tripsianes K, Zdráhal Z, Winkler C, and Harnos J. “PRICKLE3 protects VANGL proteins from CK1-mediated phosphorylation and RNF43-mediated degradation”. Commun Biol. 2025, doi: 10.1038/s42003-025-09422-9
- Novotna S, Maia LA, Radaszkiewicz KA, Roudnicky P, and Harnos J. “Linking planar polarity signaling to actomyosin contractility during vertebrate neurulation.” Open Biology, 2024, doi: 10.1098/rsob.240251
- Radaszkiewicz KA, Sulcova M, Kohoutkova E, and Harnos J. “The role of Prickle proteins in vertebrate development and pathogeny.” Molecular Cell Biochemistry, 2023, doi: 10.1007/s11010-023-04787-z

New aspects of vertebrate development:
- Laznovsky J, Kavkova M, Reis A, Robovska-Havelkova P, Maia LA, Krivanek J, Zikmund T, Kaiser J, Buchtova M, and Harnos J. “Unveiling vertebrate development dynamics in Xenopus laevis using micro-CT imaging.” GigaScience, 2024, doi: 10.1093/gigascience/giae037

Studying in-cell DNA quadruplex structures using Xenopus oocytes:
- Foldynova-Trantirkova S, Harnos J, Rynes J, Zlinska V, and Trantirek L. “In-cell NMR spectroscopy of nucleic acids: Basic concepts, practical aspects, and applications.” Progress in NMR Spectroscopy, 2025, doi: 10.1016/j.pnmrs.2025.101560.
- Ghosh A, Harnos J, Stadlbauer P, Sponer J, Lenarcic Zivkovic M, Trantirek L. Structural basis of bis-quinolinium ligands binding to quadruplex-duplex hybrids from PIM1 oncogene. Nucleic Acids Res. 2025, doi:10.1093/nar/gkaf894

Additionally, I recently developed a new biochemical approach for cloning: Paclikova P, and Harnos J. “Efficient cloning of linear DNA inserts (ECOLI) into plasmids using site-directed mutagenesis.” Scientific Reports, 2024, doi: 10.1038/s41598-024-72169-6.

RESEARCH TEAM

Postdoctoral fellows
- Katarzyna Radaszkiewicz, Ph.D., M.Sc. (currently on maternity leave)
- Lorena Agostini Maia, Ph.D.

PhD students
- Mgr. Sarka Novotna

Lab technician
- Dr. Douglas Porto Pereira Gomes

Undergraduates

Alumni
- Mgr. Pavla Kolarova (2021-2025; currently a Ph.D. student in Buchtova lab, MUNI, Czechia)
- Mgr. Aneta Poukova (2021-2025; currently a research assistant in Vacha lab, MUNI, Czechia)
- Bc. Nela Leksova (2024-2025; currently a Master’s student in Psychology, MUNI, Czechia)
- Mgr. Julie Netusilova (2022-2025; currently on maternity leave)
- Mgr. Petra Paclikova, Ph.D. (2024; currently a postdoc in Cajanek lab, MUNI, Czechia)
- Ing. Mgr. Vendula Janouskova (2023-2024; currently a Ph.D. student, Prague, Czechia)
- Mgr. Marie Sulcova, Ph.D. (2022-2023; currently a postdoc at the University of Stockholm, Sweden)
- Alba Hernández Ramos (2022-2023, Erasmus student, a practical 10-month stay, University of Salamanca, Spain)
- Mgr. Eliska Kohoutkova (2022-2023; currently a Ph.D. student at Vienna Biocenter, Austria)
- Cristina González Cuevas (2022, Erasmus student, a practical 3-month stay, University UFV in Madrid, Spain)
- Belén Escalona Pulido (2022, Erasmus student, a practical 4-month stay, University UFV in Madrid, Spain)
- Miriam Sánchez Calvo (2022, Erasmus student, a practical 4-month stay, University UFV in Madrid, Spain)