Yukio Sakiyama

Inhibition of apoptosis by the actin-regulatory protein gelsolin

Gelsolin is an actin‐regulatory protein that modulates actin assembly and disassembly, and is believed to regulate cell motility in vivo through modulation of the actin network. In addition to its actin‐regulatory function, gelsolin has also been proposed to affect cell growth. Our present experiments have tested the possible involvement of gelsolin in the regulation of apoptosis, which is significantly affected by growth. When overexpressed in Jurkat cells, gelsolin strongly inhibited apoptosis induced by anti‐Fas antibody, C2‐ceramide or dexamethasone, without changing the F–actin morphology or the levels of Fas or Bcl‐2 family proteins. Upon the induction of apoptosis, an increase in CPP32(‐like) protease activity was observed in the control vector transfectants, while it was strongly suppressed in the gelsolin transfectants. Pro‐CPP32 protein, an inactive form of CPP32 protease, remained uncleaved by anti‐Fas treatment in the gelsolintransfectants, indicating that gelsolin blocks upstream of this protease. The tetrapeptide inhibitor of CPP32(‐like) proteases strongly inhibited Fas‐mediated apoptosis, but only partially suppressed both C2‐ceramide‐ and dexamethasone‐induced apoptosis. These data suggest that the critical target responsible for the execution of apoptosis may exist upstream of CPP32(‐like) proteases in Jurkat cells and that gelsolin acts on this target to inhibit the apoptotic cell death program.

The inductive effect of interleukin-4 on IgG4 and IgE synthesis in human peripheral blood lymphocytes

Using murine monoclonal antibodies against human IgG subclasses, specific and sensitive ELISAs assay to quantify the four human IgG subclasses in cell culture supernaUints were established. The effect of human recombinant interleukin‐4 (IL‐4) on the regulation of IgG subclasses by normal peripheral blood lymphocytes was investigated. In addition to the enhancement of lgE synthesis. IL‐4 preferentially induced IgG4 synthesis in vitro, whereas IL‐4 had no effect on IgGl, IgG2, and IgG3 synthesis. IL‐4‐induced IgG4 production was blocked in a dose‐dependent manner by recombinant interferon‐gamma and anti‐human IL‐4 monoclonal antibody. Collectively, this data indicates that IL‐4 plays an important regulatory role in both IgG subclass and IgE synthesis.

Novel mutations of FOXP3 in two Japanese patients with immune dysregulation, polyendocrinopathy, enteropathy, X linked syndrome (IPEX)

Editor—Immune dysregulation, polyendocrinopathy, enteropathy, X linked syndrome (IPEX), also known as X linked autoimmunity-allergic dysregulation syndrome (XLAAD), is characterised by enteropathy and involvement of the endocrine system, such as insulin dependent diabetes mellitus (IDDM) and thyroiditis, which develop in association with autoantibodies in early infancy (MIM 304930, 304790).1 2 IPEX has been mapped to chromosome Xp11.23-Xq13.3.3 4 Recent studies have indicated that FOXP3 , a member of forkhead/winged-helix proteins, is a causative gene for both IPEX and an equivalent mouse, scurfy .5-8 Human FOXP3 consists of 11 exons and encodes 431 amino acids containing a zinc finger (Zn) domain, a leucine zipper (Zip) motif, and a forkhead domain.6 8 We have previously reported two unrelated Japanese patients with X linked autoimmune enteropathy associated with tubulonephropathy and endocrinopathy.2 9 10 We report here novel mutations in the FOXP3 gene of these patients. Clinical and laboratory findings of our patients have been previously reported.2 9 10 Briefly, patient 1, a boy, now 11 years old, was diagnosed as having autoimmune …

Spontaneous In Vivo Reversion of an Inherited Mutation in the Wiskott-Aldrich Syndrome

The Wiskott-Aldrich syndrome (WAS) is an X-linked primary immunodeficiency disease, arising from mutations of the WAS-protein (WASP) gene. Previously, we have reported that mononuclear cells from WAS patients showed lack/reduced of the intracellular WASP (WASPdim) by flow cytometric analysis, and analysis of WASP by flow cytometry (FCM-WASP) was useful for WAS diagnosis. In this study, we report a WAS patient who showed the unique pattern of FCM-WASP. The patient had the small population of normal expression of WASP (WASPbright) mononuclear cells together with the major WASPdim population. The WASPbright cells were detected in T cells, not in B cells or in monocytes. Surprisingly, the molecular studies of the WASPbright cells revealed that the inherited mutation of WASP gene was reversed to normal. His mother was proved as a WAS carrier, and HLA studies and microsatellite polymorphic studies proved that the WASPbright cells were derived from the patient himself. Therefore, we concluded that the WASPbright cells were resulted from spontaneous in vivo reversion of the inherited mutation. Furthermore, the scanning electron microscopic studies indicated that WASP-positive cells from the patient restored the dense microvillus surface projections that were hardly observed in the WASPdim cells. This case might have significant implications regarding the prospects of the future gene therapy for WAS patients.

Autosomal-dominant Hypoplastic Form of Amelogenesis Imperfecta Caused by an Enamelin Gene Mutation at the Exon-Intron Boundary

Amelogenesis imperfecta (AI) is currently classified into 14 distinct subtypes based on various phenotypic criteria; however, the gene responsible for each phenotype has not been defined. We performed molecular genetic studies on a Japanese family with a possible autosomal-dominant form of AI. Previous studies have mapped an autosomal-dominant human AI locus to chromosome 4q11-q21, where two candidate genes, ameloblastin and enamelin, are located. We studied AI patients in this family, focusing on these genes, and found a mutation in the enamelin gene. The mutation detected was a heterozygous, single-G deletion within a series of 7 G residues at the exon 9-intron 9 boundary of the enamelin gene. The mutation was detected only in AI patients in the family and was not detected in other unaffected family members or control individuals. The male proband and his brother showed hypoplastic enamel in both their deciduous and permanent teeth, and their father showed local hypoplastic defects in the enamel of his permanent teeth. The clinical phenotype of these patients is similar to that of the first report of AI caused by an enamelin gene mutation. Thus, heterogeneous mutations in the enamelin gene are responsible for an autosomal-dominant hypoplastic form of AI.

A Japanese family of X-linked auto-immune enteropathy with haemolytic anaemia and polyendocrinopathy

Three cases of X-linked auto-immune enteropathy with haemolytic anaemia and polyendocrinopathy are described from one related Japanese kindred. Two boys had died due to severe diarrhoea accompanied by total or subtotal intestinal villous atrophy.In contrast, although one patient showed the same symptoms and had circulating IgG antibodies against enterocytes, his condition improved dramatically and he developed well following the use of cyclosporin A (CSA). CSA may be beneficial in patients with this rare disorder. Auto-immune enteropathy should be considered as a cause of protracted diarrhoea with unknown aetiology.

Identification of an autoimmune enteropathy-related 75-kilodalton antigen.

BACKGROUND & AIMS We have previously reported a 75-kilodalton autoantigen specific to X-linked autoimmune enteropathy (AIE) associated with tubulonephropathy. The aim of this study was to identify the autoantigen. METHODS Complementary DNA (cDNA) clones were isolated by immunoscreening a human duodenal cDNA-expression library with serum from a patient with AIE. RESULTS cDNA encoding the 75-kilodalton antigen (AIE-75) was identified. The composite nucleotide sequence of the cDNA for AIE-75 was 2214 base pairs long and encoded 552 amino acids. The genomic sequence of AIE-75 was found in Sequence DataBank, which consisted of 21 exons and was located on the chromosome 11p14.3. Recombinant AIE-75 specifically reacted with sera from 3 of 4 unrelated patients with AIE but not with 58 control sera. AIE-75 was predominantly distributed in the epithelial cells of the luminal surface and the upper half of the crypts of the intestine and in the proximal renal tubulus. Similarity searches revealed that the AIE-75 cDNA sequence was an authentic form of several colon cancer-related cDNAs of unknown function. The deduced amino acid sequence contained 3 conserved PSD-95/Dlg/ZO-1 (PDZ) domains. CONCLUSIONS AIE-75 is a PDZ domain-containing protein expressed in the differentiated epithelial cells of the intestine and kidney and may be involved in protein-protein interaction. The identification of the autoantigen may prove useful in the approach to the pathogenesis of this poorly understood disease.

Detection of Epstein-Barr virus DNA in cardiac and aortic tissues from chronic, active Epstein-Barr virus infection associated with Kawasaki disease-like coronary artery aneurysms.

We describe three patients with chronic, active Epstein-Barr virus infection associated with Kawasaki disease-like coronary artery aneurysms. The Epstein-Barr virus genome was detected in three cardiac tissue samples and one aortic tissue sample examined by means of the polymerase chain reaction. These findings suggest that chronic Epstein-Barr virus infection may play a pathogenic role in the development of coronary artery aneurysms.

Complications of childhood Sjögren syndrome.

Sjögren syndrome (SS) is a common disorder in adults and involves both glandular and extraglandular systems. We report here four cases of childhood SS complicated by chronic thyroiditis, interstitial nephritis or sweat gland inflammation. Additionally, in one of these cases, the central nervous system was involved. All of these complications are common in adult cases.

Determination of Carrier Status for the Wiskott-Aldrich Syndrome by Flow Cytometric Analysis of Wiskott-Aldrich Syndrome Protein Expression in Peripheral Blood Mononuclear Cells

The Wiskott-Aldrich syndrome (WAS) is caused by defects in the WAS protein (WASP) gene on the X chromosome. Previous study disclosed that flow cytometric analysis of intracellular WASP expression (FCM-WASP analysis) in lymphocytes was useful for the diagnosis of WAS patients. Lymphocytes from all WAS patients showed WASPdim instead of WASPbright. Here we report that FCM-WASP analysis in monocytes could be a useful tool for the WAS carrier diagnosis. Monocytes from all nine WAS carriers showed varied population of WASPdim together with WASPbright. None of control individuals possessed the WASPdim population. In contrast, lymphocytes from all the carriers except two lacked the WASPdim population. The difference of the WASPdim population in monocytes and lymphocytes observed in WAS carriers suggests that WASP plays a more critical role in the development of lymphocytes than in that of monocytes. The present studies suggest that a skewed X-chromosomal inactivation pattern observed in WAS carrier peripheral blood cells is not fixed at the hemopoietic stem cell level but progresses after the lineage commitment.