Masayuki Hirano

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Lampreys are representatives of an ancient vertebrate lineage that diverged from our own ∼500 million years ago. By virtue of this deeply shared ancestry, the sea lamprey (P. marinus) genome is uniquely poised to provide insight into the ancestry of vertebrate genomes and the underlying principles of vertebrate biology. Here, we present the first lamprey(More)
Jawless vertebrates use variable lymphocyte receptors (VLR) comprised of leucine-rich-repeat (LRR) segments as counterparts of the immunoglobulin-based receptors that jawed vertebrates use for antigen recognition. Highly diverse VLR genes are somatically assembled by the insertion of variable LRR sequences into incomplete germline VLRA and VLRB genes. Here(More)
Because functional analysis of Fc receptors (FcRs) relies heavily on mouse models, the identification of another Fcgamma receptor is particularly noteworthy. We demonstrate that FcgammaRIV, identified here as the mouse ortholog of primate FcgammaRIII, required association of the FcR gamma-chain for optimal expression and function on myeloid cells; its(More)
Immunologists and evolutionary biologists have been debating the nature of the immune system of jawless vertebrates--lampreys and hagfish--since the nineteenth century. In the past 50 years, these fish were shown to have antibody-like responses and the capacity to reject allografts but were found to lack the immunoglobulin-based adaptive immune system of(More)
Jawed vertebrates (gnathostomes) and jawless vertebrates (cyclostomes) have different adaptive immune systems. Gnathostomes use T- and B-cell antigen receptors belonging to the immunoglobulin superfamily. Cyclostomes, the lampreys and hagfish, instead use leucine-rich repeat proteins to construct variable lymphocyte receptors (VLRs), two types of which,(More)
Jawless vertebrates (cyclostomes) have an alternative adaptive immune system in which lymphocytes somatically diversify their variable lymphocyte receptors (VLR) through recombinatorial use of leucine-rich repeat cassettes during VLR gene assembly. Three types of these anticipatory receptors in lampreys (VLRA, VLRB, and VLRC) are expressed by separate(More)
A surprising number of Fc receptor (FcR) relatives have been recognized recently with the potential capacity to modulate innate and adaptive immune responses. The six human FcR homologs (FcRH1-6), which belong to a phylogenetically conserved gene family, have variable numbers of extracellular immunoglobulin domains of five different subtypes. FcRH(More)
All jawed vertebrates produce immunoglobulins (IGs) as a defense mechanism against pathogens. Typically, IGs are composed of two identical heavy chains (IGH) and two identical light chains (IGL). Most tetrapod species encode more than one isotype of light chains. Chicken is the only representative of birds for which genomic information is currently(More)
The immunoglobulins (Igs or antibodies) as an integral part of the tetrapod adaptive immune response system have evolved toward producing highly diversified molecules that recognize a remarkably large number of different antigens. Antibodies and their respective encoding loci have been shaped by different and often contrasting evolutionary forces, some of(More)
BAFF (TNF superfamily [TNFSF] 13B/Blys) and APRIL (TNFSF13) are important regulatory factors for lymphocyte activation and survival in mammals. A BAFF/APRIL-like relative called BAFF- and APRIL-like molecule (BALM) has also been identified in cartilaginous and bony fishes, and we report in this study a BAFF-like gene in lampreys. Our phylogenetic analysis(More)