Expression and function of c-Met, a receptor for hepatocyte growth factor, during T-cell development

The c-Met oncoprotein is a cell-surface receptor for hepatocyte growth factor (HGF). Signals through HGF and c-Met have been appreciated for their crucial roles in the development of many cell types, including liver cells. The present study examined whether c-Met is expressed in the thymus and whether c-Met/HGF signals can regulate T-cell development in the thymus. We have found that mRNA transcripts encoding c-Met are expressed in mouse thymus. The c-Met transcripts were expressed at higher levels in fetal and neonatal thymus than in adult thymus, and were mostly expressed by lymphoid cells rather than by stromal cells. Interestingly, the addition of HGF to fetal thymus organ cultures increased the generation of mature T cells expressing high levels of T-cell antigen receptors. These results indicate that c-Met is expressed in the thymus during early ontogeny, and that c-Met/HGF signals can promote T-cell development.

Pertussis toxin can replace T cell receptor signals that induce positive selection of CD8 T cells

CD4+ helper T lymphocytes and CD8+ killer T lymphocytes are both generated in the thymus from common precursor cells expressing CD4 and CD8. The development of immature CD4 CD8+ thymocytes into mature 'single-positive' T cells requires T cell antigen-receptor (TCR)-mediated positive selection signals. Although it is known that the recognition specificity of TCR expressed by CD4+ CD8+ thymocytes determines their fate to become either CD4+ or CD8+ T cells, the molecular signals that direct precursor thymocytes to become CD4+ and CD8+ T cells are unclear. By using ZAP-70 mutant thymus organ cultures in which T cell development is arrested at the CD4+ CD8+ thymocyte stage, the present study shows that distinct biochemical treatments can selectively restore the generation of mature CD4+ and CD8+ T cells, bypassing TCR-induced positive selection signals. The combination of phorbol ester and ionomycin selectively restores the generation of CD4+ CD8- TCR(high) cells, consistent with previous results. On the other hand, we find that the generation of CD4- CD8+ TCR(high) cells is selectively induced by pertussis toxin. Interestingly, the signals generated by pertussis toxin, which increase Notch expression, can dominate the signals by phorbol ester and ionomycin, steering thymocyte development to CD8 lineage. These results indicate that distinct biochemical signals replace TCR signals that selectively induce positive selection of CD4+ and CD8+ T cells, and that biochemical treatment can manipulate the development and choice of CD4+ and CD8+ T cells.

Inhibition of growth and invasive activity of human pancreatic cancer cells by a farnesyltransferase inhibitor, manumycin

The effects of manumycin, a competitive farnesyltransferase (FTase) inhibitor, on pancreatic cancer cell lines with or without K-ras mutation were studied. Manumycin inhibited the growth of human pancreatic cancer cells (SUIT-2, MIA PaCa-2, AsPC-1, BxPC-3) in a dose-dependent manner. The 50% inhibitory concentration (IC50) in cell lines with a mutant K-ras gene (SUIT-2, MIA PaCa-2, AsPC-1) was lower than that in BxPC-3 with a wild-type ras. Both mitogen-activated protein kinase activity after growth stimuli and the ability for chemotactic invasion were markedly more inhibited by manumycin in SUIT-2 than in BxPC-3. These results suggest that mutated Ras is more sensitive to manumycin than the wild type. Furthermore, tumor growth and liver metastasis in nude mice inoculated with manumycin-treated SUIT-2 cells were inhibited dose dependently. Inhibition of Ras activity might be a new anticancer strategy in pancreatic cancer in which Ras plays a role.

Hepatic protein synthesis rate of liver specimens as a predictor of viability in rat cold ischemia liver transplantation model

BACKGROUND/AIMS

We have previously reported that the hepatic protein synthesis rate, calculated as the uptake rate of L-[4.5 3H] leucine by the protein fraction during a 10-min incubation of a 16-G needle biopsy specimen of liver tissue, represents a high level of liver function and is therefore useful for evaluating liver function. We investigated the hepatic protein synthesis rate level in a pre-transplant liver to learn if it might predict the outcome in a rat orthotopic liver transplantation model.

METHODS

Grafts were stored, liver specimens were obtained using a 21-G Chiba type II skinny needle, and the hepatic protein synthesis rate was calculated. Subsequently, liver transplantation was performed, and the hepatic protein synthesis rate level of revascularized liver, tissue blood flow rate, serum alanine aminotransferase, lactate dehydrogenase, hyaluronic acid, ketone body rate, and 2-week survival were examined.

RESULTS

The hepatic protein synthesis rate of pretransplant liver was correlated with parameters of post-transplant liver function: hepatic protein synthesis rate of the revascularized liver (r=0.92, p<0.0001), tissue blood flow rate (r=0.77, p<0.004), serum alanine aminotransferase (r=-0.69, p<0.003), lactate dehydrogenase (r=-0.54, p<0.03), hyaluronic acid (r=-0.86, p<0.0002), and ketone body rate (r=0.57, p<0.02). Pretransplant hepatic protein synthesis rate in survivors was 263.6+/-54.2 nmol/mg protein/10 min, while that in nonsurvivors was significantly lower at 162.0+/-39.0 (p<0.0001). When evaluation was made using a logistic regression model, the accuracy predicted using the value of hepatic protein synthesis rate was 95% (19/20).

CONCLUSIONS

These results suggest that measuring the hepatic protein synthesis rate of the grafts with a 21-G Chiba type II skinny needle may be a predictive criterion in the assessment of graft viability.

B220 expression by T lymphoid progenitor cells in mouse fetal liver

The present study has characterized T lymphoid progenitor cells that reside in mouse fetal liver. Day 14 fetal liver contains progenitor cells that can differentiate into mature T cells upon being transferred into the thymus by hanging drop cultures. Fractionation of fetal liver cells indicated that T progenitor cells were confined in TER119- CD45+ FcR(low) cells. To our surprise, B220+ rather than B220- fraction in TER119- CD45+ FcR(low) fetal liver cells exhibited efficient progenitor activity generating T cells. Progenitor activity by the B220+ fetal liver cells was restricted to T cells, B cells, and macrophages at frequency approximately 1/10, approximately 1/10, and approximately 1/20, respectively, of isolated B220+ cells. B220+ fetal liver cells did not contain detectable D-J rearrangement of TCR-beta gene and were c-kit+ IL-7R+ Thy-1- CD3- CD4(low) CD8- CD25- CD44+. B220+ fetal liver cells expressed mRNAs encoding TCR-beta, pT alpha, Ig alpha, and VpreB. Interestingly, TCR beta-chains were expressed by B220+ fetal liver cells in the VDJ-rearranged TCR-beta-transgenic mice, indicating that TCR-beta transcription and B220 expression are activated simultaneously by the transgenic B220+ fetal liver cells. These results indicate that B220 is expressed by fetal liver lymphoid progenitor cells that can become T cells, and suggest that lymphoid progenitor cells in fetal liver concurrently undergo T- and B-specific molecular events within a single cell.

B220 expression by T lymphoid progenitor cells in mouse fetal liver

The present study has characterized T lymphoid progenitor cells that reside in mouse fetal liver. Day 14 fetal liver contains progenitor cells that can differentiate into mature T cells upon being transferred into the thymus by hanging drop cultures. Fractionation of fetal liver cells indicated that T progenitor cells were confined in TER119- CD45+ FcR(low) cells. To our surprise, B220+ rather than B220- fraction in TER119- CD45+ FcR(low) fetal liver cells exhibited efficient progenitor activity generating T cells. Progenitor activity by the B220+ fetal liver cells was restricted to T cells, B cells, and macrophages at frequency approximately 1/10, approximately 1/10, and approximately 1/20, respectively, of isolated B220+ cells. B220+ fetal liver cells did not contain detectable D-J rearrangement of TCR-beta gene and were c-kit+ IL-7R+ Thy-1- CD3- CD4(low) CD8- CD25- CD44+. B220+ fetal liver cells expressed mRNAs encoding TCR-beta, pT alpha, Ig alpha, and VpreB. Interestingly, TCR beta-chains were expressed by B220+ fetal liver cells in the VDJ-rearranged TCR-beta-transgenic mice, indicating that TCR-beta transcription and B220 expression are activated simultaneously by the transgenic B220+ fetal liver cells. These results indicate that B220 is expressed by fetal liver lymphoid progenitor cells that can become T cells, and suggest that lymphoid progenitor cells in fetal liver concurrently undergo T- and B-specific molecular events within a single cell.

Clinicopathologic study of nasal T/NK-cell lymphoma among the Japanese

A high prevalence of nasal lymphoma expressing a T- or natural killer (NK)-cell phenotype (NTCL) with frequent association of Epstein-Barr virus (EBV) has been indicated in Asians. To characterize NTCL among the Japanese, the clinicopathologic features of 32 cases were evaluated and the cases were also analyzed for EBV-RNA using an ISH method. Morphologically, 31 cases were identified by atypical pleomorphic lymphoid infiltrates with polymorphous, angicentric, and necrotic features. Their lymphoma cells ranged in size from small to large and were mixed in varying proportion from case to case. The other one case showed a monomorphic 'blastic' appearance. EBV-encoded small RNA (EBER) was detected in the neoplastic cells of 27 of the 32 cases examined. In the five EBV-negative cases, one was the 'blastic' type. Clonal T-cell receptor gene rearrangement was detected in none of seven cases examined. The patients had a median follow-up of 9 months (range, 1 month to 14 years and 11 months). The Kaplan-Meier estimate of overall survival was 49% at 5 years, correlating with clinical stage. These data support the concept that most cases of NTCL are identified as tumors with T/NK-cell characteristics and EBV association, distinctly different from other peripheral T-cell lymphomas. Furthermore, the one case of an EBV-negative 'blastic' variant appears not to fit well into the pleomorphic category but more closely resembles the pathologic features of extranasal angiocentric lymphoma with lymphoblastoid appearance. This study also showed no clear difference in clinical aspects other than the original site or in prognosis, between NTCL and extranasal angiocentric lymphomas despite the higher incidence of EBV association and the tendency for that peculiar anatomical site to be restricted to the former group.

Relevance of local Th2-type cytokine mRNA expression in immunocompetent infiltrates in inflamed gingival tissue to periodontal diseases

It has been suggested that the types of inflammatory round cell infiltrates and the divergence in the cytokine production profile by macrophages and helper T cells regulate the course of infectious or inflammatory diseases, including periodontitis and gingivitis. We examined the expression of IL-1alpha, IL-1beta, IL-2, IL-4, IL-5, IL-6 and tumour necrosis factor-alpha (TNF-alpha) mRNA in the inflamed gingiva by in situ hybridization. The results of single-cell analysis were used as data sets for statistical analyses. The density of cells expressing IL-1alpha, IL-4 and IL-5 mRNA was higher in periodontitis than in gingivitis. IL-2 mRNA-expressing cells were almost absent in gingivitis specimens. Principal component analysis disclosed three factors explaining 84.8% of the variance: one accounting for 40.5% of the variance and mainly regulated by IL-1alpha, IL-1beta, IL-6 and TNF-alpha, and two others, explaining 29.9% and 14.4% of the variance, describing the relationship between the types of cytokines derived from macrophages or Th2 type. These results suggest that the cytokines produced by inflammatory cells infiltrating in the gingival tissue are influential on the progression of gingivitis, an acute and reversible inflammatory condition, to chronic and destructive periodontitis. Thus, periodontal disease progression may be regulated by the local cytokine network, and the bias in this network towards a Th2-type cytokine dominance could be an exacerbating factor.

IL-1 beta mRNA as the predominant inflammatory cytokine transcript: correlation with inflammatory cell infiltration into human gingiva

Expression of mRNA for IL-1 alpha, IL-1 beta, IL-2, IL-4, IL-5, IL-6 and TNF-alpha in inflamed gingiva was quantitatively examined by ribonuclease protection assay and in situ hybridization. The IL-1 beta mRNA expression level was statistically high (P < 0.05) in periodontitis-affected tissues compared with that in gingivitis-affected tissues. The densities of macrophages (identified as CD68-positive cells) and CD45RO-positive cells infiltrating in the inflamed gingiva correlated statistically with IL-1 beta transcript levels (macrophages, P < 0.001; CD45RO-positive cells, P < 0.002). In situ hybridization revealed IL-1 beta mRNA expression in infiltrating cells, presumed to be macrophages. The IL-1 alpha and IL-6 mRNA expression levels were much lower than the IL-1 beta transcript level, and mRNAs for IL-2, IL-4, IL-5 and TNF-alpha were negligible in these gingival tissues. The results indicate that IL-1 beta is a cytokine expressed predominantly in inflamed gingiva and reflects the density of infiltrating macrophages and other leukocytes.

CD3-induced apoptosis of CD4+CD8+ thymocytes in the absence of clonotypic T cell antigen receptor

Clonal selection of T cells mediated through the T cell antigen receptor (TCR) mostly occurs at the CD4+CD8+ double positive thymocyte stage. Immature CD4+CD8+ thymocytes expressing self-reactive TCR are induced to die upon clonotypic engagement of TCR by self antigens. CD3 engagement by antibody of the surface TCR-CD3 complex is known to induce apoptosis of CD4+CD8+ thymocytes, a process that is generally thought to represent antigen-induced negative selection in the thymus. The present study shows that the CD3-induced apoptosis of CD4+CD8+ thymocytes can occur even in TCR alpha- mutant mice which do not express the TCR alpha beta/CD3 antigen receptor. Anti-CD3 antibody induces death of CD4+CD8+ thymocytes in TCR alpha- mice either in cell cultures or upon administration in vivo. Interestingly, most surface CD3 chains expressed on CD4+CD8+ thymocytes from TCR alpha- mice are not associated with clonotypic TCR chains, including TCR beta. Thus, apoptosis of CD4+CD8+ thymocytes appear to be induced through the CD3 complex even in the absence of clonotypic antigen receptor chains. These results shed light on previously unknown functions of the clonotype-independent CD3 complex expressed on CD4+CD8+ thymocytes, and suggest its function as an apoptotic receptor inducing elimination of developing thymocytes.

Cloning of a complementary DNA encoding an 80 kilodalton nuclear cap binding protein

It has been shown that the monomethylated cap structure plays important roles in nuclear events. The cap structure has been implicated in the enhancement of pre-mRNA splicing. More recently, this structure has also been suggested to facilitate RNA transport from the nucleus to the cytoplasm. We have previously identified and purified an 80kD Nuclear Cap Binding Protein (NCBP) from a HeLa cell nuclear extract, which could possibly mediate these nuclear activities. In this report, we describe cloning of complementary DNA (cDNA) encoding NCBP. The partial protein sequences of NCBP were determined, and the full-length cDNA of NCBP was isolated from HeLa cDNA libraries. This cDNA encoded an open reading frame of 790 amino acids with a calculated molecular mass of 91,734 daltons, which contained most of the determined protein sequences. However, the protein sequence had no significant homology to any known proteins. Transfection experiments demonstrated that the epitope-tagged NCBP, transiently expressed in HeLa cells, was localized exclusively in the nucleoplasm. Similar experiments using a truncated NCBP cDNA indicated that this nuclear localization activity is conferred by the N-terminal 70 amino-acid region.

Imprint cytology of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue arising in the thymus: a case report

Low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) arising in the thymus is a very rare tumor with characteristic morphologic features. We describe a case of thymic low-grade B-cell MALT lymphoma occurring in a 59-yr-old woman with Sjögren's syndrome, in whom the definite diagnosis was difficult at the time of surgery. An immunohistologic and genotypic study, however, was diagnostic of lymphoma. A review of cytologic material was undertaken, and it was felt that the cytologic features in Giemsa-stained preparations in imprint smears were present that initially should have enabled the correct cytodiagnosis and distinction from the other thymic lesions. The findings presented in this study were considered to contribute to the cytodiagnosis of a thymic lesion, which might, in the past, have been erroneously interpreted as another lymphoproliferative disorder.

Morphometrical and biochemical analysis on autofluorescent granules in various tissues and cells of the rats under several nutritional conditions

The effects of age and nutritional conditions on accumulation of autofluorescent granules in various organs and tissues of male Sprague-Dawley rats were compared morphometrically. The relative intensity of the specific fluorescence of these autofluorescent granules was similar in all tissues and cells examined. In almost all cases, there were more autofluorescent granules in the 12-month experiment than in the 4-month one. Multiple necrotic foci of myofibrils with an accumulation of autofluorescent granules were seen in striated muscles in the rats on vitamin E-deficient diets for 12 months. In splenocytes, renal proximal convoluted tubules and hepatic cells, autofluorescent granules quantitatively increased significantly with an increase of the corn oil contents in the diets. The increase was rather marked in the splenocytes and renal epithelia of vitamin E-deficient rats. In the Purkinje cells and bronchial epithelial cells, no significant differences were noted according to the difference in the vitamin E and corn oil contents in diets. The accumulation of autofluorescent granules was not merely considered to be an age-related change, but to be influenced by a relationship to the cell metabolism and functional activity in various organs.

Age changes of myofibrils of human minor pectoral muscle

Micro- and ultramicromeasuring studies have been made on the age changes of surgically resected minor pectoral muscles in 200 Japanese females of various ages (26-80 years). With advancement of age, muscle fibers of type I decreased in number and increased in size, and the age-related increase in size is not considered to be due to an increase in number of myofibrils but seems to be due to an increase in their volume resulting from an increase in the number of myofilaments.

Age changes in size and number of muscle fibers in human minor pectoral muscle

Micromeasuring studies have been made on the senile changes of the surgically resected minor pectoral muscles in 200 Japanese females of various ages (26-80 years). The microscopic differentiation between type I (red) and type II (white) fibers were made by the histochemically demonstrated myosin-ATPase activity with frozen sections and also by the immunohistochemical demonstration of beta-enolase in the paraffin sections with indirect antibody method. The decrease with age in weight of the muscle was not markedly observed. Muscle fibers of type I were significantly decreased in number and increased in size after 60 years of age. However, size of muscle fibers of type II decreased gradually after 40 years of age. However, size of muscle fibers of type II decreased gradually after 40 years of age. Total volume of type I muscle fibers was not changed according to age, on the contrary, that of the type II fibers decreased significantly after 60 years of age.

The progress of adrenoleukodystrophy as revealed by auditory brainstem evoked responses and brainstem histology

Serial studies of auditory brainstem evoked responses (ABR) and slow vertex responses (SVR) were obtained during the progress of adrenoleukodystrophy in a 6-year-old boy. This child was normal until 5 years of age. His illness began with a gait disturbance, dysarthria, and hearing difficulty. Later, spastic paralysis, serious deafness, and blindness appeared. He died of respiratory failure 2 years after the onset. The ABR was normal at onset but changed to an abnormal pattern. Initially, there was lengthening of the wave V-I interpeak interval. This was followed by the disappearance of the later components as his general condition deteriorated. At the terminal stage, only a prolonged wave I was recordable. The postmortem pathology revealed demyelination of auditory nerves and remarkable neuronal loss in the auditory pathways of the brainstem; in addition, there was a variety of extensive degeneration throughout the cerebrum, in particular the complete degeneration of the white matter with secondarily occurring ganglionic cell changes. These date suggest that degeneration of the brainstem from rostral to caudal levels occurred.