Smad family proteins are identified as intracellular signal mediators of the TGF-β superfamily.In this study,we identified two novel members of the Smad family,termed as AmphiSmad1/5/8 and AmphiSmad4,from Chinese amphioxus.Both AmphiSmad1/5/8 and AmphiSmad4 showed a typical domain structure of Smad proteins consisting of conserved MH1 and MH2 domains.Phylogenetic analysis placed AmphiSmad1/5/8 in the Smad1,5 and 8 subgroup of the R-Smad subfamily,and AmphiSmad4 in the Co-Smad subfamily.The spatial and temporal gene expression patterns of AmphiSmad1/5/8 and AmphiSmad4 showed that they may be involved in the embryonic development of notochord,myotome and alimentary canal,and may help to establish the specification of dorsal-ventral axis of amphioxus.Moreover,AmphiSmad1/5/8 and AmphiSmad4 showed extensive distribution in all adult tissues examined,suggesting that these two genes may play important roles in the morphogenesis of a variety of tissues especially notochord and gonad.
Toll-like receptors (TLRs) and NK cell receptors are the most important receptor superfamilies in innate immunity. TLRs act as the sensor of external pathogens, while NK cells detect alterations in endogenous protein expression on target cells through activating and inhibitory receptors. Accumulating data has demonstrated that TLRs and NK cell receptors can coordinate and regulate each other during immune responses, which contributes to the initiation of innate response and the priming of adaptive responses. TLRs can activate NK cell function directly or with the help of accessory cells in a cytokine or cell-to-cell contact dependent manner. More understanding of the recognition of innate receptors and interactions between them may provide important insights into the design of effective strategies to combat tumor and microbial infections. In this review, we summarize how TLRs and NK cells discriminate the self or non-self components respectively. And importantly, we pay more attention to the role of TLR sig-naling in induction of NK cell activation, responses and the crosstalk between them.
Myocyte enhancer factor 2 proteins are members of MADS family of transcription factors, which can control the expression of muscle-specific genes in vertebrates. However, not all Mef2 genes are es-sential for muscle development in invertebrates. Here we have isolated a full-length cDNA from am-phioxus, designated AmphiMef2. The predicted amino acid sequence has highly conserved MADS and MEF2 domains, showing higher identity with the corresponding regions of its homologues in verte-brates than those in invertebrates. Results from whole-mount in situ hybridization show that the ex-pression of AmphiMef2 initially appears in the presomitic mesoderm at early neurula stage, then the transcripts are detected in both the somites and the unsegmented presomitic mesoderm. At 36 h larval stage, the expression is only detected in the posterior somites. By 48 h larval stage, the expression is shifted to the preoral pit (a homologous organ to the vertebrate adenohypophysis) and persists until at least 72 h larval stage. The results suggest that AmphiMef2 may be not only involved in the myogenesis but also the development or function of the preoral pit in amphioxus.
