Evidence for a Large Expansion and Subfunctionalization of Globin Genes in Sea Anemones
GENOME BIOLOGY AND EVOLUTION
Authors: Smith, Hayden L.; Pavasovic, Ana; Surm, Joachim M.; Phillips, Matthew J.; Prentis, Peter J.
Abstract
The globin gene superfamily has been well-characterized in vertebrates, however, there has been limited research in early-diverging lineages, such as phylum Cnidaria. This study aimed to identify globin genes in multiple cnidarian lineages, and use bioinformatic approaches to characterize the evolution, structure, and expression of these genes. Phylogenetic analyses and in silico protein predictions showed that all cnidarians have undergone an expansion of globin genes, which likely have a hexacoordinate protein structure. Our protein modeling has also revealed the possibility of a single pentacoordinate globin lineage in anthozoan species. Some cnidarian globin genes displayed tissue and development specific expression with very few orthologous genes similarly expressed across species. Our phylogenetic analyses also revealed that eumetazoan globin genes form a polyphyletic relationship with vertebrate globin genes. Overall, our analyses suggest that a Ngb-like and GbX-like gene were most likely present in the globin gene repertoire for the last common ancestor of eumetazoans. The identification of a large-scale expansion and subfunctionalization of globin genes in actiniarians provides an excellent starting point to further our understanding of the evolution and function of the globin gene superfamily in early-diverging lineages.
The Role of Neuroglobin in the Neuroprotection of Limb Ischemic Preconditioning in Rats
MOLECULAR NEUROBIOLOGY
Authors: Li, Shu-Qin; Li, Wen-Bin; Zhang, Min; Wu, Yu-Zhou; Hu, Yu-Yan
Abstract
Recent evidence suggests that limb ischemic preconditioning (LIP) protects neurons against cerebral ischemia-reperfusion injury. However, the mechanisms of LIP are not well understood. Neuroglobin (Ngb) is a recently discovered globin that affords protection against hypoxic/ischemic brain injury. This study was performed to investigate the role of Ngb in the neuroprotection of LIP against brain ischemia and the involvements of mitochondria in the process. The rat global brain ischemic model was used, and the CA1 hippocampus was selected as the observational target. Ngb expression was investigated by RT-PCR and Western blot. Neuropathological evaluation was performed by thionin staining. Mitochondrial membrane potential (Delta psi m), Na+-K+-ATPase activity, and ultrastructure were examined by flow cytometry, spectrophotometry, and transmission electron microscopy, respectively. We also used Ngb antisense oligodeoxynucleotides (AS-ODNs) and Ngb inducer hemin to inhibit or mimic the effect of LIP. We found that LIP significantly up-regulated Ngb expression and protected neurons against ischemia. Furthermore, LIP effectively improved deterioration in the Delta psi m, mitochondrial Na+-K+-ATPase activity, and ultrastructure induced by cerebral ischemia. These effects of LIP were inhibited partly by Ngb AS-ODNs and mimicked by hemin. It could be concluded that up-regulation of Ngb expression played an important role in the neuroprotection induced by LIP, and the Ngb-mediated neuroprotection of LIP was, at least partly, associated with mitochondria.