The Extracellular Adenosine Deaminase Growth Factor, ADGF/CECR1, Plays a Role in Xenopus Embryogenesis via the Adenosine/P1 Receptor

Ryoko Iijima,Takekazu Kunieda,Shinji Yamaguchi,Hiroko Kamigaki,Ikuko Fujii-Taira,Kazuhisa Sekimizu,Takeo Kubo,Shunji Natori,Koichi J Homma

doi:10.1074/jbc.m709279200

Abstract

Adenosine deaminase-related growth factors (ADGF), also known as CECR1 in vertebrates, are a novel family of growth factors with sequence similarity to classical cellular adenosine deaminase. Although genes for ADGF/CECR1 have been identified in both invertebrates as well as vertebrates, their in vivo functions in vertebrates remain unknown. We isolated cDNA clones for two cerc 1s from Xenopus laevis. Both recombinant Xenopus CECR1s exhibited adenosine deaminase and growth factor activity, and the adenosine deaminase activity was found to be indispensable for growth factor activity. The Xenopus cerc 1s are expressed in the somites, pronephros, eyes, cement gland, neural tube, and neural floor plate of the embryos. Knock-down of these two genes using morpholino oligonucleotides caused a reduction in the body size and abnormalities of the body axis in the Xenopus embryos, accompanied by selective changes in the expression of developmental marker genes. Injection of adenosine, agonists for adenosine/P1 receptors, or adenosine deaminase inhibitor into late gastrula archenteron embryos resulted in developmental defects similar to those caused by morpholino oligonucleotide injection. These results show, for the first time, the involvement of CECR1s via the adenosine/P1 receptors in vertebrate embryogenesis via regulation of extracellular adenosine concentrations.

Highlights

Sine deaminase-related growth factor (ADGF)3 family is a novel group of growth factors with sequence similarity to classical adenosine deaminase (ADA) in their carboxyl-terminal regions [1,2,3]
As Insect-derived growth factor (IDGF) was originally identified as a growth factor in an embryonic cell line [1] and ADA activity was shown to be indispensable for growth factor activity [3], it is plausible that the Adenosine deaminase-related growth factors (ADGF)/CECR1 family plays a role in cell proliferation during morphogenesis and organogenesis via its ADA activity
We first amplified a cDNA fragment of the Xenopus cecr1 homologue using degenerate primers designed according to the amino acid sequences conserved among human, pig, and zebrafish CECR1s; this was due to the lack of information regarding the nucleotide sequence of the Xenopus homologue of CECR1 on commencement of this study

Summary

Introduction

Sine deaminase-related growth factor (ADGF)3 family is a novel group of growth factors with sequence similarity to classical adenosine deaminase (ADA) in their carboxyl-terminal regions [1,2,3]. There were no differences in the expression patterns between Xl_cecr1-1 and Xl_cecr1–2 in RT-PCR using gene-specific primers (data not shown).

Results

Conclusion