Anxa4 Genes are Expressed in Distinct Organ Systems in Xenopus laevis and tropicalis But Are Functionally Conserved

Karine L. Massé, Robert Collins, Surinder Bhamra, Rachel A. Seville and Elizabeth A. Jones

volume 3 | issue 2

october/november/december 2007

Purchase article for $19

Subscribe to this journal for $59/year

» Log in

Anxa4 belongs to the multigenic annexin family of proteins which are characterised by their ability to interact with membranes in a calcium-dependent manner. Defined as a marker for polarised epithelial cells, Anxa4 is believed to be involved in many cellular processes but its functions in vivo are still poorly understood. Previously, we cloned Xanx4 in Xenopus laevis (now referred to as anxa4a) and demonstrated its role during organogenesis of the pronephros, providing the first evidence of a specific function for this protein during the development of a vertebrate. Here, we describe the strict conservation of protein sequence and functional domains of anxa4 during vertebrate evolution. We also identify the paralog of anxa4a, anxa4b and show its specific temporal and spatial expression pattern is different from anxa4a. We show that anxa4 orthologs in X. laevis and tropicalis display expression domains in different organ systems. Whilst the anxa4a gene is mainly expressed in the kidney, Xt anxa4 is expressed in the liver. Finally, we demonstrate Xt anxa4 and anxa4a can display conserved function during kidney organogenesis, despite the fact that Xt anxa4 transcripts are not expressed in this domain. This study highlights the divergence of expression of homologous genes during Xenopus evolution and raises the potential problems of using X. tropicalis promoters in X. laevis.

Authors

Karine L. Massé

Molecular Physiology Group, Department of Biological Sciences, University of Warwick; Coventry UK

Robert Collins

The Medical School, University of Warwick; Coventry UK

Surinder Bhamra