Eri Kikkawa

Rapid Evolution of Major Histocompatibility Complex Class I Genes in Primates Generates New Disease Alleles in Humans via Hitchhiking Diversity

A plausible explanation for many MHC-linked diseases is lacking. Sequencing of the MHC class I region (coding units or full contigs) in several human and nonhuman primate haplotypes allowed an analysis of single nucleotide variations (SNV) across this entire segment. This diversity was not evenly distributed. It was rather concentrated within two gene-rich clusters. These were each centered, but importantly not limited to, the antigen-presenting HLA-A and HLA-B/-C loci. Rapid evolution of MHC-I alleles, as evidenced by an unusually high number of haplotype-specific (hs) and hypervariable (hv) (which could not be traced to a single species or haplotype) SNVs within the classical MHC-I, seems to have not only hitchhiked alleles within nearby genes, but also hitchhiked deleterious mutations in these same unrelated loci. The overrepresentation of a fraction of these hvSNV (hv1SNV) along with hsSNV, as compared to those that appear to have been maintained throughout primate evolution (trans-species diversity; tsSNV; included within hv2SNV) tends to establish that the majority of the MHC polymorphism is de novo (species specific). This is most likely reminiscent of the fact that these hsSNV and hv1SNV have been selected in adaptation to the constantly evolving microbial antigenic repertoire.

Trans-species polymorphism of the Mhc class II DRB-like gene in banded penguins (genus Spheniscus).

The Major Histocompatibility Complex (Mhc) class II DRB locus of vertebrates is highly polymorphic and some alleles may be shared between closely related species as a result of balancing selection in association with resistance to parasites. In this study, we developed a new set of PCR primers to amplify, clone, and sequence overlapping portions of the Mhc class II DRB-like gene from the 5′UTR end to intron 3, including exons 1, 2, and 3 and introns 1 and 2 in four species (20 Humboldt, six African, five Magellanic, and three Galapagos penguins) of penguin from the genus Spheniscus (Sphe). Analysis of gene sequence variation by the neighbor-joining method of 21 Sphe sequences and 20 previously published sequences from four other penguin species revealed overlapping clades within the Sphe species, but species-specific clades for the other penguin species. The overlap of the DRB-like gene sequence variants between the four Sphe species suggests that, despite their allopatric distribution, the Sphe species are closely related and that some shared DRB1 alleles may have undergone a trans-species inheritance because of balancing selection and/or recent rapid speciation. The new primers and PCR assays that we have developed for the identification of the DRB1 DNA and protein sequence variations appear to be useful for the characterization of the molecular evolution of the gene in closely related Penguin species and might be helpful for the assessment of the genetic health and the management of the conservation and captivity of these endangered species.

Genomic structure around joining segments and constant regions of swine T‐cell receptor α/δ (TRA/TRD) locus

A complete genomic region of 131·2 kb including the swine T‐cell receptor α/δ constant region (TRAC/TRDC) and joining segments (TRAJ/TRDJ) was sequenced. The structure of this region was strikingly conserved in comparison to that of human or mouse. All of the 61 TRAJ segments detected in the human genomic sequence were detected in the swine sequence and the sequence of the protein binding site of T early alpha, the sequence of the α enhancer element and the conserved sequence block between TRAJ3 and TRAJ4 are highly conserved. Insertion of the repetitive sequences that interspersed after the differentiation of the species in mammals such as short interspersed nucleotide elements is markedly suppressed in comparison to other genomic regions, while the composition of the mammalian‐wide interspersed sequences is relatively conserved in human and swine. This observation indicates the existence of a highly selective pressure to conserve this genomic region around TRAJ throughout the evolution of mammals.

Human leukocyte antigen may predict outcome of primary recurrent spontaneous abortion treated with paternal lymphocyte alloimmunization therapy.

Recurrent spontaneous abortion (RSA) is defined by at least three consecutive abortions in otherwise healthy couples. Paternal lymphocyte alloimmunization therapy (PLAT) is an effective therapy for RSA in some cases, but there are no predictive markers about the effectiveness of PLAT.

Analysis of the sequence variations in the Mhc DRB1-like gene of the endangered Humboldt penguin (Spheniscus humboldti)

The Major Histocompatibility Complex (Mhc) genomic region of many vertebrates is known to contain at least one highly polymorphic class II gene that is homologous in sequence to one or other of the human MhcDRB1 class II genes. The diversity of the avian Mhc class II gene sequences have been extensively studied in chickens, quails, and some songbirds, but have been largely ignored in the oceanic birds, including the flightless penguins. We have previously reported that several penguin species have a high degree of polymorphism on exon 2 of the Mhc class II DRB1-like gene. In this study, we present for the first time the complete nucleotide sequences of exon 2, intron 2, and exon 3 of the DRB1-like gene of 20 Humboldt penguins, a species that is presently vulnerable to the dangers of extinction. The Humboldt DRB1-like nucleotide and amino acid sequences reveal at least eight unique alleles. Phylogenetic analysis of all the available avian DRB-like sequences showed that, of five penguin species and nine other bird species, the sequences of the Humboldt penguins grouped most closely to the Little penguin and the mallard, respectively. The present analysis confirms that the sequence variations of the Mhc class II gene, DRB1, are useful for discriminating among individuals within the same penguin population as well those within different penguin population groups and species.

Modified S/MAR episomal vectors for stably expressing fluorescent protein-tagged transgenes with small cell-to-cell fluctuations

We modified and tested scaffold/matrix attachment region (S/MAR) episomal vectors. The new vectors would be useful in obtaining cells stably expressing fluorescent protein-tagged transgenes with small, mostly within 10-fold cell-to-cell fluctuations. In the vectors, the same transcript directs episomal replication and expression of transgene/antibiotic marker, and only antibiotic selection without any other extra steps was sufficient to obtain desired stable cells, including those expressing two different proteins simultaneously. Furthermore, the two test cases (expression of human growth hormone in AtT20 and four protein kinase C isoforms in HEK293) would prove to be useful in visualizing and analyzing regulatory processes involving these proteins.

Metabolic surgery for inadequately controlled type 2 diabetes in nonseverely obese Japanese: a prospective, single-center study

BACKGROUND The beneficial effects of metabolic surgery on weight loss, glycemic control, and cardiovascular improvement for the morbidly obese patient has been vast and undeniable. It is also expected to be effective in diabetic patients with less severe obesity, but the evidence is yet to yield significant impact. OBJECTIVE In this study, we investigate the impact of metabolic surgery on inadequately controlled type 2 diabetes in Japanese patients with mild obesity. SETTING Private practice, Japan. METHODS Twenty-eight consecutively selected diabetic patients with body mass index 27.5 to 34.9 kg/m2, who had inadequately controlled diabetes despite intensive medical treatments, underwent laparoscopic sleeve gastrectomy with duodenojejunal bypass, and were prospectively followed up for 12 months. The primary endpoint was a composite of proposed parameters of optimal diabetes management of glycosylated hemoglobin (HbA1C)<7.0%, low-density lipoprotein cholesterol<100 mg/dL, and systolic blood pressure<130 mm Hg. RESULTS At enrollment, the HbA1C was 9.4 ± 1.3% and the duration of diabetes was 11.7 ± 7.4 years. After the short-term low-calorie diet intervention, the preoperative baseline body mass index and HbA1C were 31.0 ± 1.5 kg/m2 and 8.5 ± 1.3%, respectively. At 1 year, body mass index and HbA1C dropped to 24.7 ± 2.3 kg/m2 and 6.8 ± .8%, respectively. Those who achieved HbA1C<6.5% without diabetes medications, and those with HbA1C<7% were 23% and 54% compared with 0% and 3.6% at baseline (P = .007 and P<.001), respectively. Although the ratio of those who achieved the composite endpoint did not reach statistical significance, positive impacts were also observed on hypertension, dyslipidemia, medication usage, and quality of life. There were 3 major surgical morbidities and no mortalities. CONCLUSIONS Gastrointestinal metabolic surgery in nonmorbidly obese Japanese with inadequately controlled type 2 diabetes may have additional metabolic benefits.