Annexin Animal Models-From Fundamental Principles to Translational Research

Abstract

Routine manipulation of the mouse genome has become a landmark in biomedical research. Traits that are only associated with advanced developmental stages can now be investigated within a living organism, and the in vivo analysis of corresponding phenotypes and functions advances the translation into the clinical setting. The annexins, a family of closely related calcium (Ca²⁺)- and lipid-binding proteins, are found at various intra- and extracellular locations, and interact with a broad range of membrane lipids and proteins. Their impacts on cellular functions has been extensively assessed in vitro, yet annexin-deficient mouse models generally develop normally and do not display obvious phenotypes. Only in recent years, studies examining genetically modified annexin mouse models which were exposed to stress conditions mimicking human disease often revealed striking phenotypes. This review is the first comprehensive overview of annexin-related research using animal models and their exciting future use for relevant issues in biology and experimental medicine.

Keywords: KO mice; annexins; calcium; extracellular annexin functions; human disease models; membrane organization; membrane trafficking.

Figure 1

Annexin structural organization. (A) Schematic overview of annexins. Magenta, N-terminal tails; light to dark green, C-terminal core domains with Annexin repeats 1–4 and 5–8 for AnxA6; grey, short spacer regions between tail and first Annexin repeat or between Annexin repeats; blue, AnxA6 linker region. (B) 3D-structures of human AnxA1 (PDB: 1AIN [17]) and (C) bovine AnxA6 (PDB: 1AVC [18]) cores (light to dark green, spacer regions in grey, AnxA6 linker region in blue), with coordinated calcium ions (red). 3D-structures are visualized with the iCn3D software vs. 2.24.6; (https://www.ncbi.nlm.nih.gov/Structure/icn3d/icn3d.html; accessed 12 March 2021).