The Impact of c-Fos/Activator Protein-1 Inhibition on Allogeneic Pancreatic Islet Transplantation

Unpreventable allograft rejection is one of the main problems in pancreatic islet transplantation (PIT). Therefore, it is imperative to develop a more effective immunosuppressive strategy. The blockade of transcription factors has been a central part of T cell-depleting immunosuppressive therapies, as typified by the use of calcineurin inhibitors. The inhibition of activator protein-1 (AP-1) offers a novel strategy for immunosuppression in PIT, although to date, no reports on the effects of AP-1 inhibition are available. In this study, we investigated the immunosuppressive effects of T-5224, a c-Fos/AP-1-selective inhibitor, on murine T cells activated by αCD3+αCD28 mAbs. T-5224 inhibited proliferation, CD25 up-regulation, and the production of IL-2 and interferon-γ. In addition, T-5224 blocked the nuclear translocation of c-Fos/AP-1 in activated murine T cells. In BALB/c (H-2(d) )-to-C57BL/6J (H-2(b) ) mouse PIT, the 2-week administration of T-5224 prolonged survival of 600 islet allografts in a dose-dependent manner. When combined with a 2-week low-dose tacrolimus, the T-5224 treatment markedly prolonged allograft survival to over 300 days, while the efficacy was indeterminate when transplanted islet allograft mass was reduced to 300. We conclude that the c-Fos/AP-1 inhibition by T-5224 is a potentially attractive strategy for allogeneic PIT.

ASKP1240, a fully human anti-CD40 monoclonal antibody, prolongs pancreatic islet allograft survival in nonhuman primates

A strategy for inhibiting CD40 has been considered as an alternative approach for immunosuppression because of undesirable effects of anti-CD154 monoclonal antibodies (mAbs). Previously, we demonstrated that ASKP1240, which is a fully human anti-CD40 mAb, significantly prolonged kidney and liver allograft survival in cynomolgus monkeys without causing thromboembolic complications. Herein, we evaluated the effect of ASKP1240 on pancreatic islet transplantation (PITx) in cynomolgus monkeys. Diabetes was induced by total pancreatectomy, and islet allografts were transplanted into the liver. Following PITx (8201-12 438 IEQ/kg), blood glucose levels normalized promptly in all animals. Control islet allografts were rejected within 9 days (n = 3), whereas ASKP1240 (10 mg/kg) given on postoperative days 0, 4, 7, 11 and 14 (induction treatment, n = 5) significantly prolonged graft survival time (GST) to >15, >23, 210, 250 and >608 days, respectively. When ASKP1240 (5 mg/kg) was administered weekly thereafter up to post-PITx 6 months (maintenance treatment, n = 4), GST was markedly prolonged to >96, >115, 523 and >607 days. During the ASKP1240 treatment period, both anti-donor cellular responses and development of anti-donor antibodies were abolished, and no serious adverse events were noted. ASKP1240 appears to be a promising candidate for immunosuppression in clinical PITx.

Association of klotho gene polymorphism with bone density and spondylosis of the lumbar spine in postmenopausal women

Based on the fact that the klotho-deficient mouse exhibits multiple aging phenotypes, including osteopenia and subchondral sclerosis of joints, we explored the possibility of whether human klotho gene polymorphism is associated with two major age-related skeletal disorders: osteoporosis and spondylosis. Analysis of the CA repeat sequence downstream of the final exon of the klotho gene identified ten types of alleles in Japanese postmenopausal women (n = 377). We investigated the association of this microsatellite polymorphism with bone density and spondylosis score of the lumbar spine. None of the genotypes was associated with bone density in the overall population (n = 377; 754 alleles) nor in the subpopulation at not more than 10 years after menopause (<or=10 years, n = 131; 262 alleles). However, the type 5 allele was significantly associated with low bone density in aged subpopulations at 10-20 years after menopause (n = 144; 288 alleles, p = 0.035) and >20 years after menopause (n = 102; 204 alleles, p = 0.024). The type 7 allele was associated with high bone density in women more than 20 years after menopause (p = 0.042). The association study with spondylosis of postmenopausal women (n = 221) revealed that another distinct allele, type 8, was significantly associated with low spondylosis score at L-4/5 (p = 0.019) and L-5/S-1 (p = 0.048) levels in the subpopulation equal to or younger than the average age (<or=63 years old, n = 119; 238 alleles), but not in the older subpopulation. These findings indicate that the klotho gene may be a candidate for the genetic regulation of common age-related diseases like osteoporosis and spondylosis, and we provide the first evidence suggesting that this gene may be involved in the etiology of human diseases.

Isolation of novel mouse genes associated with ectopic ossification by differential display method using ttw, a mouse model for ectopic ossification

Mouse mutant ttw (tiptoe walking) is an excellent model for ectopic ossification. This mutant exhibits ossification in various soft tissues, which is histologically similar to human OPLL (ossification of posterior longitudinal ligament of the spine). We previously reported that ttw is caused by a nonsense mutation of the nucleotide pyrophosphatase (ENPP1) gene, and that a polymorphism of the human ENPP1 gene is associated with OPLL. These facts indicate that ENPP1 regulates ectopic ossification in vivo; however, the mechanism is unclear. ENPP1 is an ectoenzyme that generates phosphate (Pi) and pyrophosphate (PPi). PPi is a strong inhibitor of ossification. Abnormal Pi metabolism is observed in patients with OPLL, and diseases with abnormal Pi metabolism such as hypophosphatemic rickets are frequently complicated by ectopic ossification. These lines of evidence suggest Pi-PPi metabolism associated with ENPP1 may play an important role in regulation of ectopic ossification. To clarify the molecular mechanism of ectopic ossification in ttw, we examined the effect of dietary phosphate and calcium on the ttw phenotype and found a high dietary phosphate-accelerated ectopic ossification. Then we examined genes associated with the enhanced ossification in ttw on a high phosphate diet by a differential display method. We identified nine mouse genes; six genes were up-regulated by the high phosphate diet, and three were down-regulated. Six of the nine genes were novel and we cloned and characterized them. Two of the genes were highly specific to cartilage, suggesting their specific role in enchondral ossification. Our identification of the novel genes would give novel insight into the mechanism of ectopic ossification and etiology of OPLL.

Identification of sequence polymorphisms of the COMP (cartilage oligomeric matrix protein) gene and association study in osteoarthrosis of the knee and hip joints

Osteoarthrosis (OA) is a common cause of musculoskeletal disability characterized by late-onset degeneration of articular cartilage. Although several candidate genes have been reported, susceptibility genes for OA remain to be determined. Hereditary osteochondral dysplasias produce severe, early-onset OA and hence are models for common idiopathic OA. Among them are pseudoachondroplasia and multiple epiphyseal dysplasia, both of which are caused by mutations in the cartilage oligomeric matrix protein (COMP) gene. Therefore, COMP may be a susceptibility gene for OA. We screened for polymorphisms by direct sequencing of all exons of the COMP gene with their flanking intron sequences and the promoter region. We identified 16 polymorphisms, of which 12 were novel. Using six polymorphisms spanning the entire COMP gene, we examined the association of COMP in Japanese patients with OA of the knee and hip joints. Genotype and allele frequencies of the polymorphisms were not significantly different between OA and control groups, and there was no significant difference in haplotypes. These results do not support an association between COMP and OA in the Japanese population.

Isolation, characterization, and mapping of the mouse and human WDR8 genes, members of a novel WD-repeat gene family

The Trp-Asp (WD) motif has been shown to exist in a number of proteins. Genes containing repeats of the WD motif compose a large gene family associated with a variety of cellular functions and can be divided into a number of functional subfamilies. By means of the differential display method using ttw, a mouse model for the early stage of ectopic ossification, we have identified a novel mouse gene, Wdr8 (WD repeat domain 8), which contains two WD repeats, together with its human orthologue. The human and mouse WDR8 genes encode 460 and 462 amino acids, respectively, with 89% identity, and are expressed in almost all tissues, including bone and cartilage, and in bone-forming cells, including osteoblasts and chondrocytes. Wdr8 expression in cartilage was differentially displayed by stimuli for ectopic ossification in ttw and was observed strongly only at a transition period from hypertrophic to mineralizing stages in ATDC5, a chondrogenic cell line that exhibits endochondral ossification, suggesting a potential role for Wdr8 in the process of ossification. The WDR8 protein is highly conserved among a variety of species, but is distinctly different from other WD-repeat proteins, indicating that it represents a novel subfamily of the WD-repeat gene family.

Isolation, characterization and mapping of the mouse and human PRG4 (proteoglycan 4) genes

PRG4 (proteoglycan 4) has been identified as megakaryocyte stimulating factor and articular superficial zone protein. PRG4 has characteristic motifs including somatomedin B and hemopexin domains, a chondroitin sulfate-attachment site and mucin-like repeats. During a screen of genes implicated in ectopic ossification, we found a novel mouse gene highly homologous to human and bovine PRG4 genes. Here, we report isolation, characterization and mapping of the gene, Prg4 together with characterization of its human orthologue. Prg4 cDNA was 3,320 bp long, encoding a 1,054 amino-acid protein. Human and mouse PRG4 genes each consisting of 12 exons spanned 18 and 16 kb, respectively. Characteristic motifs were conserved across species; however, the mucin-like repeat regions were highly diverse in length between species with a tendency that larger animals had longer repeats. Expression of human and mouse PRG4 genes was similar and found not only in cartilage, but also in liver, heart, lung, and bone. Expression of the mouse gene increased with progression of ectopic ossification. Multiple tissue-specific splicing variants lacking some of the motifs were found in both human and mouse. Although a specific role in the articular joint has previously been reported, the presence of multi-functional motifs as well as unique expression and alternative splicing patterns suggest that PRG4 functions in several distinctive biological process including regulation of ossification.

A polymorphic variant at the Werner helicase (WRN) gene is associated with bone density, but not spondylosis, in postmenopausal women

Werner syndrome (WS) is a rare autosomal recessive progeroid syndrome characterized by the premature onset of multiple age-related disorders. The gene responsible for WS has been identified as WRN, a member of the RecQ family of helicase genes. Based on the fact that patients with WS exhibit osteoporosis and osteoarthritis, the present study was undertaken to clarify the contribution of the WRN gene to the etiology of these two common age-related disorders in normal postmenopausal women. We investigated the association of a WRN gene polymorphism, namely c.4330 T --> C leading to an amino acid substitution from Cys to Arg, with bone density and lumbar spondylosis score in unrelated Japanese postmenopausal women (n = 377). Genotypic frequencies of T/T, T/C, and C/C were 87.5%, 12.2%, and 0.3%, respectively. Bone density of the lumbar spine (L2-4) was significantly lower in women carrying the minor C allele than in non-carriers (P = 0.037). When bone density was expressed by the Z score after being adjusted by age and weight, carriers of the C allele showed lower values not only in the lumbar spine, but also in the total body (P = 0.015 and 0.042, respectively). The association study with spondylosis in postmenopausal women (n = 221) revealed that this polymorphism was not related to the severity of spondylosis expressed by the Kellgren-Lawrence score at any disk level of the lumbar spine (L2/3-L5/S1). These findings indicate that the WRN gene may be a candidate for the genetic regulation of osteoporosis, but not spondylosis, in normal Japanese postmenopausal women.

Structure of cytochrome c6 from the red alga Porphyra yezoensis at 1. 57 A resolution

The crystal structure of cytochrome c(6) from the red alga Porphyra yezoensis has been determined at 1.57 A resolution. The crystal is tetragonal and belongs to space group P4(3)2(1)2, with unit-cell parameters a = b = 49.26 (3), c = 83.45 (4) A and one molecule per asymmetric unit. The structure was solved by the molecular-replacement method and refined with X-PLOR to an R factor of 19.9% and a free R factor of 25.4%. The overall structure of cytochrome c(6) follows the topology of class I c-type cytochromes in which the heme prosthetic group covalently binds to Cys14 and Cys17, and the iron has an octahedral coordination with His18 and Met58 as the axial ligands. The sequence and the structure of the eukaryotic red algal cytochrome c(6) are very similar to those of a prokaryotic cyanobacterial cytochrome c(6) rather than those of eukaryotic green algal c(6) cytochromes.

Cloning and characterization of human and mouse PROSC (proline synthetase co-transcribed) genes

Large-scale DNA sequencing, coupled with in silico gene trapping, is a robust approach to identifying unknown genes in selected genomic regions. Using this approach we have isolated a novel human gene, PROSC (for proline synthetase co-transcribed [bacterial homolog]), from human chromosome 8p11.2, and its mouse counterpart. The human PROSC gene spanned 17 kb of genomic DNA; its cDNA was 2530 bp long, with 8 exons that included an open reading frame of 825 bp (275 amino acids). The mouse cDNA (Prosc), 1995 bp long, was predicted to encode 274 amino acids. PROSC is ubiquitously expressed in human tissues and has been highly conserved among divergent species from bacteria to mammals, suggesting its important cellular function. The gene product is likely to be a soluble cytoplasmic protein, but its function remains to be determined.

Cloning and characterization of a novel gene (C8orf2), a human representative of a novel gene family with homology to C. elegans C42.C1.9

Large-scale sequencing of selected genomic regions, coupled with in silico gene trapping, is a robust approach to identifying previously unknown genes. In this way we have found a gene (C8orf2) that is highly homologous to C. elegans C42C1.9. C8orf2 was situated on 8p11. 2 between STS markers NIB1979 (proximal) and AFMA295ZD5 (distal), oriented toward the centromere. C8orf2 consisted of 16 exons spanning more than 16.5 kb of genomic DNA, and was expressed ubiquitously in human tissues. The gene encoded 339-and 152-amino acid polypeptides by alternative splicing; the larger variant contained a region extremely rich in charged amino acids, in particular lysine and glutamic acid. C8orf2 also bore sequence homology to the human KE04p gene. Its conservation among highly divergent species suggests that C8orf2 belongs to a novel gene family.

Cloning and characterization of ASH2L and Ash2l, human and mouse homologs of the Drosophila ash2 gene

Drosophila ash2 belongs to the trithorax (trx) gene family. The ash2 product positively regulates expression of homeotic selector genes, and is implicated in early development and formation of various disc patterns in the fruit fly. Through large-scale sequencing of human genomic DNA coupled with in silico gene trapping, we identified a gene (ASH2L) on chromosome 8p11.2 whose predicted product was highly homologous to ash2, characterized it, and identified its mouse counterpart. The human ash2 cDNA is 2368 bp long, encoding 628 amino acids. The 16-exon gene spans more than 34 kb of genomic DNA between STS markers WI-9207 (centromere) and AFMA295ZD5 (telomere) on chromosome 8, with transcription oriented telomere to centromere. The ash2 genes are highly conserved among different species, including C. elegans and yeast. The presence of a conserved bipartite nuclear localization signal and a PHD finger motif in the human ash2 gene suggests that the gene product would function as a transcriptional regulator in humans, as its homologue does in Drosophila.

Association of the human NPPS gene with ossification of the posterior longitudinal ligament of the spine (OPLL)

OPLL (ossification of the posterior longitudinal ligament of the spine) is a common form of human myelopathy with a prevalence of as much as 4% in a variety of ethnic groups. To clarify the genetic factors that predispose to OPLL, we have studied ttw (tiptoe walking), a mouse model that presents ectopic ossification of the spinal ligaments similar to OPLL and have found that the ttw phenotype is caused by the nonsense mutation of the gene encoding nucleotide pyrophosphatase (NPPS), a membrane-bound glycoprotein thought to produce inorganic pyrophosphate, a major inhibitor of calcification and mineralization. To investigate a possible role of NPPS in the etiology of OPLL, we have examined its genetic variations in OPLL patients. A total of 323 OPLL patients was screened by means of polymerase chain reaction/single-strand conformation polymorphism analysis covering all the exons and their surrounding introns, plus about 1.5-kb of the promoter region. We identified ten nucleotide variations in the NPPS gene; five of the alterations caused amino-acid substitutions, and two of them were found specifically in OPLL patients. Subsequently, we performed an association study using these variations and found a significant association of an allele, viz., a deletion of T at a position 11 nucleotides upstream from the splice acceptor site of intron 20 (IVS20-11delT), with OPLL; the proportion of the individuals having this deletion was significantly higher (P = 0.0029) in OPLL patients than in controls, indicating that those who have this variation may be more susceptible to the abnormal ossification of the spinal ligaments. Thus, our study suggests that NPPS plays an important role in the etiology of human OPLL.

New method for measuring area of spinal canal after double-door laminoplasty

In the double-door laminoplasty procedure used for patients with cervical myelopathy, techniques to obtain a wider spinal canal have been tested. We hypothesized that making the lateral gutters as lateral as possible may be effective for obtaining a wider spinal canal. In this study we aimed to test our hypothesis by using a new measurement method to assess the postoperative cross-sectional area of the spinal canal. Fifty-six vertebrae were operated on in 11 patients, using the STSS spacer (Asahi Optical, Tokyo, Japan). On computed tomography (CT) scans, the most posterior edge of a space-occupying lesion was defined as point A and a horizontal line through point A was drawn parallel to the posterior wall of the vertebral body (line X). Two oblique lines were drawn along the medial margin of the bilateral split laminae (lines R and L). The triangular area enclosed by lines X, R, and L was defined as the substantial area of the spinal canal (SASC). A horizontal line through the median points of the bilateral facet joint in the anteroposterior direction was defined as line B. According to the relative position of line X to line B, two types of vertebra were observed: In type 1, line X was located ventral to line B; in type 2, line X was located dorsal to line B. The mean data values for type 1 vertebra were: SASC, 133.1 mm2; ATD, 22.9 mm; angle R, 61.3 degrees; and angle L, 61.8 degrees. The mean data values for type 2 vertebra were: SASC, 99.8 mm2; ATD, 20.1 mm; angle R, 58.6 degrees; and angle L, 57.5 degrees. There were significant differences between types 1 and 2 vertebrae in values both for SASC and ATD (P < 0.01). There were no significant differences between types 1 and 2 vertebrae regarding angles R and L. The difference in SASC in the two types appeared to arise from the difference in ATD. In other words, the degree of enlargement of the spinal canal was determined not by the inclination of the bilateral split laminae, but by the transverse diameter. This result supports the validity of our hypothesis. In a double-door laminoplasty, to obtain a wider spinal canal, the lateral gutters must be made as lateral as possible (i.e., at the medial border of the facet joints, especially in type 2 vertebra). On the preoperative CT scan, the relative positions of the large-volume lesion and the facet joint must be noted.