Expression Patterns of CAPN1 and CAPN8b Genes during Embryogenesis in Xenopus laevis

Lucie Abrouk-Vérot,Claire Brun,Jean-Marie Exbrayat

doi:10.4236/cellbio.2013.24024

Abstract

Calpains are a superfamily of Ca2+-dependent cysteine proteases, implicated in various cellular processes and thus probably necessary in all the stages of cell life. The first extended report of quantification of total RNAs within the developmental stages of Xenopus laevis was described in this study. Decreases of total RNAs were positively associated with waves of apoptotic cell death (onset of gastrulation, and morphogenesis). Using qPCR, the temporal expression pattern of CAPN1 and CPAN8b (XCL-2) were characterized during the Xenopus laevis embryogenesis. Transcripts of the CAPN1 and CAPN8 genes were detectable from gastrula stage and their levels oscillated throughout development. The expression of the CAPN1 (mu/I) gene was observed in earliest stage, indicating a maternal origin, while expression of the CAPN8b gene was detectable after midblastula transition. The levels of the two transcripts then started to rise again obviously as a result of zygotic expression (stage 11). The CAPN1 gene expression was particularly expressed at tailbud stage, while the CAPN8 transcripts were found at gastrula, neurula and tailbud stages. This is the first report of quantification of mRNAs CAPN8b and CAPN1 (mu/I) within the developmental stages of Xenopus laevis by qPCR.

Highlights

Found in all eucaryotes and some bacteria, the multigenic calpain family encodes calcium-dependent cysteine proteases that vary in their domain structure, expression and substrate specificity [1]
The aim of the present paper is to compare during the embryogenesis of Xenopus laevis the expression profiles of a well-known calpain, the calpain 1 (CAPN1), with a calpain that is less studied, the CAPN-8b
A light decrease of the concentration of total RNA was observed at stage 11 and was positively associated with a maternal cell death program which is set up at fertilization and abruptly activated at the onset of gastrulation (10.5) [21]

Summary

Introduction

Found in all eucaryotes and some bacteria, the multigenic calpain family encodes calcium-dependent cysteine proteases that vary in their domain structure, expression and substrate specificity [1]. The ubiquitously expressed calpain 1 (CAPN1) is well characterized [4] It is a heterodimeric enzyme consisting of a large catalytic subunit (80 kDa) and a small regulatory subunit (30 kDa), common with the calpain 2. These two enzymes have mostly indistinguishable substrate and they are ubiquitously expressed, but they differ in the in vitro Ca2+ requirement (μM versus mM) for the proteolytic activity. The large and small subunits contain four (I-IV) and two (V-VI) domains respectively: the regulatory N-terminal domain (I), the protease domain (II), the C2-domain-like Ca2+/phospholipid-binding domain (III), the penta-EF-hand domain (IV and VI) and the Glyclustering hydrophobic domain (V). In the presence of Ca2+, the binding of Ca2+ to domains II, III, IV and the domain VI induces some conformational changes that allow domain II to form a single active domain [5]

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