Hiroko Tsuji

Novel polymorphisms and haplotypes in the human coagulation factor XIII A-subunit gene

Abstract Novel polymorphic sites within the coding region of the human coagulation factor XIII A-subunit (F13A) gene and their haplotypic combinations with the other polymorphic sites thus far reported are presented. Polymorphic bands were detected in exons 2, 5, 8, 12 and 14 by using single strand conformational polymorphism analysis and antithetic forms of the polymorphic exons were linked with each other, cosegregating as distinct sequence haplotypes. In Finnish, German, and Russian populations a total of 18 haplotypes were observed of possible 72 haplotypic combinations of the 5 exons. Ten of the haplotypes detected were found to have no novel mutations but to be only combinations of preexisting mutations. No tightly associated combinations in pairwise comparisons between antithetic forms of the polymorphic exons were observed, indicating that there may be recombinational hotspots within the F13A gene region.

A de novo recombination in the ABO blood group gene and evidence for the occurrence of recombination products

Abstract We have encountered a paternity case where exclusion of the putative father was only observed in the ABO blood group (mother, B; child, A1; putative father, O), among the many polymorphic markers tested, including DNA fingerprints and microsatellite markers. Cloning a part of the ABO gene, PCR-amplified from the trio’s genomes, followed by sequencing the cloned fragments, showed that one allele of the child had a hybrid nature, comprising exon 6 of the B allele and exon 7 of the O1 allele. Based on the evidence that exon 7 is crucial for the sugar-nucleotide specificity of A1 and B transferases and that the O1 allele is only specified by the 261G deletion in exon 6 of the consensus sequence of the A1 allele, we concluded that the hybrid allele encodes a transferase with A1 specificity, resulting, presumably, from de novo recombination between the B and O1 alleles of the mother during meiosis. Screening of random populations demonstrated the occurrence of four other hybrid alleles. Sequencing of intron VI from the five hybrid alleles showed that the junctions of the hybrid alleles were located within intron VI, the intron VI-exon 7 boundaries, or exon 7. Recombinational events seem to be partly involved in the genesis of sequence diversities of the ABO gene.

Immunolocalisation of the janus kinases (JAK)—signal transducers and activators of transcription (STAT) pathway in human epidermis

The janus kinases (JAK) and signal transducers and activators of the transcription (STAT) pathway have been shown to be activated by a number of cytokines or growth factors and to play significant roles in the differentiation of various cell types. In the present study, we investigated the distribution of the JAK–STAT pathway using immunohistochemistry in the human epidermis. Each element of the pathway showed abundant and differential expression in the epidermis. The differential distribution of the elements was most strikingly observed in the horny keratinised cell and granular layers of the epidermis. JAK2, JAK3, STAT1 and STAT5 were expressed in high amounts, and JAK1, TYK2, STAT2, STAT3, STAT4 and STAT6 to a much lesser extent in the horny cell layer. JAK3, TYK2, STAT2, STAT3, STAT4 and STAT6 were more abundantly expressed in the granular layer than the lower layers of the epidermis. JAK1, STAT1 and STAT5 were expressed at almost the same levels in the various layers of the epidermis. These results show that elements of the JAK–STAT pathway are abundantly and differentially expressed in the epidermis. It is suggested that each element of the pathway may play a role at a distinct stage of keratinocyte differentiation.

Immunolocalization of the mitogen-activated protein kinase signaling pathway in Hassall's corpuscles of the human thymus.

In the present study, we investigated the immunohistochemical localization of mitogen-activated protein kinase (MAPK) signaling pathway in the human thymus. Three members of MAPK, the extracellular signal-regulated kinase (ERK), the c-Jun N-terminal kinase (JNK) and the p38 kinase, showed differential expression patterns in the thymus medulla. The phosphorylated form of ERK (p-ERK) was abundantly present in the outer layer of Hassalls corpuscles, and the phosphorylated form of p38 kinase (p-p38 kinase) was present in the entire Hassalls corpuscles. The phosphorylated form of JNK (p-JNK) was expressed in medullary thymocytes. We also examined localization of MAPK kinases (MAPKK or MEK) which specifically activate MAPK. MEK1, an activator of ERK, was found in the outer layer of Hassalls corpuscles where p-ERK was expressed. MEK3, an activator of p38 kinase, was also expressed in the outer layer. MEK4 and MEK7, which are activators of JNK, were present in the entire Hassalls corpuscles. Thus, differential expression of MAPK in the thymus supports the concept that the MAPK signaling pathway controls the specificity of functional thymic responses to extracellular stimuli. Furthermore, the abundant expression of various elements of the pathway in Hassalls corpuscles suggests that the pathway is involved in thymic medullary epithelial maturation.

Sibling incest and formulation of paternity probability: case report.

Paternity determination of a fetus whose mother was admitted to an institution for the welfare and health of handicapped persons was requested of us by a doctor and lawyer of the institution. The fetus was recovered by a legal artificial abortion based on the Act on Maternity Health and Welfare (Japan) with the permission of the custodian. Commercially available MCT118, HLADQA, PM, and 9 STRs were tested for DNA samples from the fetus, the mother, her younger brother, her father, her grandfather, and 4 staff members of the institution. Only the brother was not excluded and the paternity probability was estimated at 99.857% on the basis of newly formulated expressions for multiallelic loci on the assumption of sibling incest. We concluded then that the fetus was fathered by the brother. DNA fingerprinting with multilocus and single locus minisatellite probes which were performed to confirm the paternity also support the conclusion. Bandsharing frequencies between the family members, however, did not necessarily reflect their actual kinship, which findings suggest that multilocus DNA fingerprinting requires further accumulation of data for consanguineous cases such as incest. Universal formulation for calculating paternity probability for a sibling incest case on the basis of multiallelic monolocus polymorphisms is also presented.

Immunohistochemical study of the phosphorylated and activated form of c-Jun NH2-terminal kinase in human aorta.

Abstractc-Jun NH2-terminal kinase is a key enzyme mediating the cellular response to a variety of extracellular stimuli. In the present study, we performed immunohistochemical studies of the expression of the phosphorylated form of the kinase in 51 human aortas of various ages. The phosphorylated kinase immunoreactivity was strongly detected in vascular smooth muscle cells of the medial vessel layer of atherosclerotic lesions from adults. Immunoreactivity was also strongly detected in similar cells of the intima. On the other hand, immunoreactive phosphorylated kinase was only weakly detected in the medial vascular smooth muscle cells of non-atherosclerotic lesions from adults. We also investigated the expression of the phosphorylated kinase in infant aortas. In contrast to its weak immunoreactivity in adult non-atherosclerotic lesions, the kinase immunoreactivity was detected in high amounts in vascular smooth muscle cells of non-atherosclerotic lesions from infants. Thus, the abundant expression of the phosphorylated kinase in these cells in atherosclerotic lesions of adults and non-atherosclerotic lesions of infants suggests that the activation of c-Jun NH2-terminal kinase may be an important element initiating the proliferation of vascular smooth muscle cells during atherogenesis and aortic development.

Immunohistochemical study of tyrosine phosphorylation signaling in the involuted thymus

Thymic involution has been reported to be an important parameter of the degree and duration of child abuse. In the present study, we assessed the status of tyrosine phosphorylation signaling, which is known to play a key role in the physiological function of the thymus, in involuted thymuses of abused children through immunohistological studies performed with anti-phosphotyrosine antibodies. We found that tyrosine-phosphorylated proteins were present in high amounts in Hassalls corpuscles (HC) in the medulla of control thymuses. In involuted thymuses of abused children, expression of tyrosine-phosphorylated proteins was reduced with accompanying morphological changes of HC, such as reduction in size or calcification. These findings lead us to the suggestion that tyrosine phosphorylation signaling is reduced in involuted thymuses of abused children and that reduction of the signaling may be associated with morphological changes of HC as observed in involuted thymuses of abused children. In order to certify the suggestion, we investigated expression of tyrosine-phosphorylated proteins in involuted thymuses of stressed rats as well as in control thymuses. Immunohistochemistry revealed that tyrosine-phosphorylated proteins were expressed in control thymuses, more abundantly in the medulla, and reduced remarkably in involuted thymuses of stressed rats. Further, immunoblot analysis also showed that expression of phosphotyrosine-containing proteins was reduced in thymus extracts of involuted thymuses of stressed rats, thus supporting the suggestion. Our results also raise the possibility that components of tyrosine phosphorylation signaling could be a molecular marker for thymic involution.

Immunohistochemical study of tyrosine phosphorylation signaling in Hassa N's corpuscles of the human thymus

Tyrosine phosphorylation signaling has been reported to play a key role in thymocyte development. However, the physiological role of signaling in thymus stroma is poorly understood, and there is lack of information on the in situ localization of elements of the signaling pathway in thymus stroma. In the present study, we have found by immunohistochemical analysis that tyrosine-phosphorylated proteins are present in high amounts in Hassalls corpuscles of the thymus medulla. Hassalls corpuscles represent end stages of maturation of thymic medullary epithelium. We have also investigated the localization of the src family that is involved in tyrosine phosphorylation signaling in Hassalls corpuscles. A member of the src family protein tyrosine kinases, p59fyn, was shown to be abundantly expressed in the outer layer of Hassalls corpuscles. Another member of the family, p60c-src, was highly expressed in the entire Hassalls corpuscles. Furthermore, p50csk and p130cas, both of which are involved in the pathway, were shown to be preferably expressed in the outer layer of Hassalls corpuscles. These findings suggest that tyrosine phosphorylation signaling may play a role in thymic medullary epithelial maturation and that the src family is involved in the process.

Expression of the janus kinases – signal transducers and activators of transcription pathway in Hassall's corpuscles of the human thymus

Abstract. The janus kinases (JAK) and signal transducers and activators of transcription (STAT) pathway has been shown to play a key role in cytokine-mediated signal transduction, and to regulate growth, differentiation, and death of both normal and transformed cells. In the present study, we investigated immunohistochemically the distribution of the JAK-STAT pathway in the human thymus. Various elements of the pathway were abundantly expressed in Hassalls corpuscles, located in the thymus medulla and representing terminal stages of the thymic medullary epithelium. Furthermore, the elements of the pathway showed distinct localization in Hassalls corpuscles. JAK1, JAK2, and TYK2 were expressed in high amounts in the entirety of Hassalls corpuscles, whereas JAK3 was in the outer layer. STAT1, STAT2, and STAT6 were abundantly expressed in the entire Hassalls corpuscles, whereas STAT5 was in the outer layer. These findings strongly suggest that the JAK-STAT pathway may play a role in thymic medullary epithelial maturation.

Possible involvement of Fyn kinase in ethanol-stimulated Cas tyrosine phosphorylation in rat cerebellum and cerebral cortex.

In the present study, we have investigated the effect of intraperitoneal injection of ethanol (3.5 g/kg) on tyrosine phosphorylation in rat brain. Immunoblot analysis using an antiphosphotyrosine antibody revealed that a 130‐kDa protein band was detected in the brain extract in response to ethanol administration. This ethanol‐stimulated tyrosine phosphorylation of the 130‐kDa protein was found in the brain but not in the heart, liver or thymus. The 130‐kDa phosphotyrosine‐containing protein was identified by immunoprecipitation to be Cas, a crk‐associated src substrate. This ethanol‐stimulated tyrosine phosphorylation of Cas was observed most prominently in the cerebellum and the cerebral cortex. We further examined the possible involvement of Fyn kinase in ethanol‐stimulated Cas tyrosine phosphorylation. Immunecomplex kinase assay showed that Fyn was activated in the cerebellum and cerebral cortex of ethanol‐administered rats. Immunoprecipitation experiments also showed that Fyn was co‐immunoprecipitated with an anti‐Cas antibody in these regions from ethanol‐administered rats. Furthermore, exogenous Fyn was shown to phosphorylate Cas from cerebellum and cerebral cortex in vitro. These findings indicate that ethanol stimulates tyrosine phosphorylation of Cas in rat cerebellum and cerebral cortex, and that Fyn may be involved in the process.