Biochemical and Functional Characterization of the Three Zebrafish Transglutaminases 2

Area of Science:

• Biochemistry
• Molecular Biology
• Developmental Biology

Background:

• Transglutaminase 2 (TG2) is a protein with diverse roles in physiological and pathological processes.
• TG2's functions are often debated due to context-dependent effects (localization, cell type, experimental conditions).
• Zebrafish (Danio rerio) is a valuable animal model for in vivo biological studies.

Purpose of the Study:

• To characterize the enzymatic and functional properties of zebrafish TG2 (zTGs2) proteins.
• To establish zebrafish as a reliable model for in vivo TG2 research.
• To compare zTGs2 functions with human TG2 (hTG2).

Main Methods:

• Confirmed three human TG2 orthologs (zTGs2) in the zebrafish genome.
• Expressed and purified recombinant zTGs2 proteins.
• Assayed Ca2+-dependent transamidation activity and inhibition by specific inhibitors.
• Evaluated zTGs2's role in RGD-independent cell adhesion in human fibroblasts.
• Investigated intracellular zTGs2's role in apoptosis in HEK293 cells.

Main Results:

• Zebrafish possess three TG2 orthologs (zTGs2) with confirmed expression and function during embryonic development.
• Recombinant zTGs2 exhibited Ca2+-dependent transamidation activity, inhibitable by specific TG2 inhibitors, mirroring hTG2.
• zTGs2 mediated RGD-independent cell adhesion in a human fibroblast model.
• Intracellular zTGs2 demonstrated a comparable protective/damaging role in apoptosis to hTG2 in transfected HEK293 cells.

Conclusions:

• Zebrafish TG2 proteins (zTGs2) exhibit biochemical and functional properties highly similar to their human orthologs.
• These findings support the utility of zebrafish as an in vivo model for investigating TG2 functions.
• The study provides a foundation for future in vivo research on TG2 roles using zebrafish.