Abstract
Mitogen-activated protein kinase (MAPK) cascades are fundamental signal transduction modules in all eukaryotic organisms, participating growth and development, as well as stress response. In the present study, three MAPK genes were successfully identified from the genome of Chlamys farreri, respectively, named CfERK1/2, CfJNK, and Cfp38, and only one copy of ERK, JNK, and p38 were detected. Domain analysis indicated that CfMAPKs possessed the typical domains, including S_TKc, Pkinase, and PKc_like domain. Phylogenetic analysis showed that three CfMAPKs of MAPK subfamilies exists in the common ancestor of vertebrates and invertebrates. All CfMAPKs specifically expressed during larval development and in adult tissues, and the expression level of CfERK1/2 and Cfp38 was apparently higher than that of CfJNK. Under heat stress, the expression of CfERK1/2 and Cfp38 were significantly downregulated and then upregulated in four tissues, while the expression of CfJNK increased in all tissues; these different expression patterns suggested a different molecular mechanism of CfMAPKs for bivalves to adapt to temperature changes. The diversity of CfMAPKs and their specific expression patterns provide valuable information for better understanding of the functions of MAPK cascades in bivalves.
Highlights
The Zhikong scallop, Chlamys farreri (Jones, 1904, known as Chinese scallop), naturally distributes along the coasts of Northern China, Korea, Japan, and Eastern Russia, which usually live a semisessile lifestyle by attaching itself to rocks and other hard surfaces with byssal threads (Shumway and Parsons, 2016)
CfERK1/2 and CfJNK were composed of 11 exons and 10 introns; Cfp38 was composed of 8 exons and 7 introns (Figure 1)
The length of some exons was similar among the three CfMAPKs
Summary
The Zhikong scallop, Chlamys farreri (Jones, 1904, known as Chinese scallop), naturally distributes along the coasts of Northern China, Korea, Japan, and Eastern Russia, which usually live a semisessile lifestyle by attaching itself to rocks and other hard surfaces with byssal threads (Shumway and Parsons, 2016). High temperature affects the physiological and biochemical responses of marine organisms, which are driven by the regulation of gene expression (Hornstein et al, 2018; Rahman et al, 2019; Zhang et al, 2020). Mitogen-activated protein kinases (MAPKs) are protein Ser/Thr kinases that transmit extracellular signals and cause many intracellular reactions (Cargnello and Roux, 2011). This process is realized by the cascade reaction of conservative MAPK, mitogen-activated protein kinase (MAPKK), and mitogenactivated protein kinase (MAPKKK). The MAPK mainly has three subfamilies, including extracellular signal regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and p38 (Johnson and Lapadat, 2002). Many studies have found that MAPK played important roles in controlling the response of cells to the environment, extensively participating in various physiological processes such as cell growth, cell differentiation, proliferation, and apoptosis (Johnson and Lapadat, 2002; Morrison, 2012)
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