Intestinal epithelial culture under an air-liquid interface: a tool for studying human and mouse esophagi

This study investigated whether an intestinal epithelial culture method can be applied to mouse and human esophageal cultures. The esophagi harvested from 1-day-old mice and adult humans were maintained in collagen gels. A commercially available culture medium for human embryonic stem cells was used for the human esophageal culture. We discovered that the intestinal epithelial culture method can be successfully applied to both mouse and human esophageal cultures. The long-term cultured esophageal organoids were rod-like luminal structures lined with myofibroblasts. We discovered that regeneration of the esophageal mucosal surface can be almost completely achieved in vitro, and the advantage of this method is that organoid cultures may be generated using host-derived fibroblasts as a niche. This method is a promising tool for mouse and human research in intestinal biology, carcinogenesis, and regenerative medicine.

RhoA and RhoC proteins promote both cell proliferation and cell invasion of human oesophageal squamous cell carcinoma cell lines in vitro and in vivo

There is growing evidence that Rho proteins are deregulated by overexpression in tumours; and according to some reports, this correlates with disease progression. Our previous clinical study had demonstrated a correlation between RhoA expression and tumour progression in oesophageal squamous cell carcinoma (ESCC). These findings prompted us to study, using nude mice, pathological roles of Rho proteins in human ESCC cells. Western blot analysis in ESCC cell lines, in addition to cell proliferation and in vitro migration assays, were performed to observe the malignant potential of RhoA and RhoC in untransfected and transfected cells. Constitutively active RhoA, RhoC and dominant negative RhoA (dnRhoA) proteins were transfected to ESCC (TE-1 and TE-2) cells. The stably transfected cells were injected into nude mice, and the growth and metastasis of these cells to the lungs were analysed. Tumour tissues were then examined using immunohistochemical methods for proteins Ki-67 (MIB-1), FAK, MMP-1, MMP-9 and TIMP-3. Protein levels of RhoA and RhoC in ESCC cell lines were visualised by Western blotting, and showed highest expression in TE-2 cells. Results from the migration assay illustrated that both RhoA and RhoC play a role in migration of ESCC cells. In TE-2 transfected cells, RhoC showed greater migration compared to RhoA. By using an experimental metastasis model in nude mice, RhoA was found to promote more tumour growth than RhoC, whereas RhoC induced lung metastasis in comparison to RhoA. Ki-67 labelling index was used to evaluate the proliferation potential of tumour tissue inoculated from nude mice. In TE-2 cells RhoA gave a proliferation capacity of 24.8+/-0.5, which was significantly higher than those of TE-2 RhoC 10+/-0.4 (P<0.01). Strong immunoreactivity for FAK, MMP-1 and MMP-9 proteins was present in all tumour cells. By contrast, loss of TIMP-3 expression was observed in all tumour cells. In conclusion, our results indicate that pro-oncogenic Rho proteins are involved in promoting tumour growth, cell migration and metastasis in human ESCC cells in nude mice. The results from this study suggest that active Rho proteins may induce a transforming effect that leads to a malignant phenotype.

Effect of perioperative steroid therapy on the postoperative course of patients with oesophageal cancer

BACKGROUND

Perioperative steroid therapy is often used in oesophageal cancer surgery and we evaluate the effect of this therapy on the secretory leukocyte protease inhibitor levels in the lungs (a major antiprotease in the conducting airways) and postoperative course in oesophageal cancer patients.

METHODS

Twenty-one patients operated on for oesophageal cancer in 2003-2004 were treated with perioperative steroid therapy (250 mg of methylprednisolone intravenously 1 h before the operation). Fifteen consecutive patients operated on in 2002 served as a control group. Secretory leukocyte protease inhibitor in bronchoalveolar lavage fluid and the postoperative course in the two groups were compared.

RESULTS

The mortality rate was 0% and there was no significant difference in the morbidity rate between the two groups. Days of intubation and systemic inflammatory response syndrome were significantly shorter for the steroid group. The bronchoalveolar lavage fluid secretory leukocyte protease inhibitor level was significantly higher in the steroid group than in the control group on postoperative days 2 and 3. The secretory leukocyte protease inhibitor level on postoperative day 3 was remarkably lower for the patients intubated for > or = 5 days and for those with pulmonary complications.

CONCLUSION

Perioperative steroid therapy increased the bronchoalveolar lavage fluid secretory leukocyte protease inhibitor level and reduced the days of intubation and systemic inflammatory response syndrome in patients with oesophagectomy.

RASSF1A gene promoter methylation in esophageal cancer specimens

SUMMARY. RASSF1A is frequently inactivated by promoter methylation in human cancers. To understand the involvement of the RASSF1A gene in esophageal squamous cell cancer (ESCC), we investigated the methylation of the RASSF1A gene in primary ESCC to define the frequency of this epigenetic aberration and its clinicopathological significance. Methylation-specific polymerase chain reaction (MSP) was used to detect RASSF1A gene methylation in DNA from 55 cases of ESCC. Methylation of the RASSF1A gene was found in 13 of 55 (24%) cases of primary ESCC. No association was found between the promoter methylation of the RASSF1A gene in primary ESCC and age, gender, localization, invasion depth, or tumor stage. Association was found with tumor differentiation. There was no correlation with its prognosis. In conclusion, it was suggested that an inactivation of the RASSF1A gene due to promoter methylation was associated with de-differentiation of the tumor in ESCC.

Correlation between RhoA overexpression and tumour progression in esophageal squamous cell carcinoma

AIMS

The aim of this study was to clarify the clinico-pathologic outcome and prognostic significance of RhoA in esophageal squamous cell carcinoma (ESCC).

METHODS

Immunohistochemical staining for RhoA was performed on surgical specimens obtained from 122 patients with ESCC.

RESULTS

There were significant correlations among RhoA overexpression and TNM clinical classification (depth of invasion, P=0.028; presence of regional lymph node metastasis, P=0.009; presence of distant metastasis, P=0.003; staging P=0.006), lymphatic invasion (P=0.002), and blood-vessel invasion (P=0.004). The five-year survival rates for ESCC patients with RhoA overexpression were significantly lower than those in patients with RhoA under-expression (P=0.002).

CONCLUSIONS

Our results demonstrated immunohistochemically that the expression of RhoA protein appeared to be correlated with tumour progression of ESCC. Patients with RhoA overexpression tended to have poor prognosis compared with patients with RhoA under-expression.

Expression of heat-shock protein Hsp60 correlated with the apoptotic index and patient prognosis in human oesophageal squamous cell carcinoma

Cellular stress response and apoptosis are two highly conserved mechanisms for maintaining homeostasis. Hsp60 and Hsp90 have been shown to play pro- and anti-apoptotic roles, respectively. Our present study examined whether there is a correlation between the expression of Hsp60 and Hsp90, clinical parameters, the apoptotic index (AI), and the prognosis of patients with oesophageal squamous cell carcinoma (ESCC). We immunohistochemically stained cells for Hsp60, Hsp90, and single-stranded DNA (ssDNA), which acts as an apoptotic marker. In normal oesophageal epithelium tissue, Hsp60 and Hsp90 were expressed in the cytoplasm and membrane from the basal cell layer to the supra-basal cell layers. Hsp60 and Hsp90 positive stainings (+) were found in 63 of 123 cases (51%) and 62 of 123 cases (50%), respectively. There was no correlation between Hsp60 and Hsp90 expression levels and any of the clinical parameters examined. The five-year survival rate for ESCC patients with Hsp60 (+) expression was significantly higher than for those patients with Hsp60 (-) expression (P=0.0371). Five-year survival rates of patients with Hsp60 (+) and (-) were 49% and 33%, respectively. By contrast, Hsp90 expression failed to predict patient prognosis (P=0.7965). The high-AI group did not have a significantly better prognosis than the low-AI group (P=0.2218). Statistical analysis showed a significant correlation between the expression of Hsp60 and AI in ESCC patients (P=0.008). Thus, the five-year survival rate for the high-AI/Hsp60 (+) group was statistically significantly better than for the other groups (P=0.0281). The results obtained in this study indicate that positive Hsp60 expression is a good prognostic indicator. This may be due to its role as a chaperone in contributing to the induction of apoptosis. These data suggest that Hsp60 expression correlates with the AI and patient prognosis in human ESCC.

An immunohistochemical study of TIMP-3 expression in oesophageal squamous cell carcinoma

Tissue inhibitor of metalloproteinase-3 (TIMP-3) inhibits the activity of matrix metalloproteinase, which may play an important role in carcinoma invasion and metastasis. We have investigated the relationship between TIMP-3 reduction and clinicopathological factors in oesophageal squamous cell carcinoma (ESCC). We examined tissue specimens that had been removed from 90 patients with thoracic oesophageal cancer who had undergone surgery between 1983 and 2001. Immunohistochemical staining was performed by the standard streptavidin–biotin method. Immunostaining of TIMP-3 was seen in the cytoplasm of cancer cells and normal oesophageal epithelial cells, particularly in cells located in shallow areas of the tumour. TIMP-3 preserved (+), moderate (±), and reduced (−) cases accounted for 30, 27, and 33 of the 90 patients, respectively (33, 30, 37%). Significant correlations were observed between TIMP-3 expression and depth of tumour invasion (P=0.001), number of lymph node metastases (P=0.003), infiltrative growth pattern (P=0.003), and disease stage (P=0.005). The survival rates of patients with TIMP-3 (−) cancer were significantly lower than those of patients with TIMP-3 (+) and TIMP-3 (±) cancer (P=0.0003). The mean 5-year survival rates of patients with TIMP-3 (+), (±), and (−) were 50, 58, and 21%, respectively. In conclusion, decreased expression of TIMP-3 protein correlates with invasive activity and metastasis. This makes the prognosis for patients with cancer that has lost TIMP-3 significantly less favourable than that for patients with cancer that has maintained TIMP-3.

Interferon-gamma and granulocyte colony-stimulating factor in bronchoalveolar lavage fluid after oesophagectomy

BACKGROUND

Activated polymorphonuclear leucocytes play a pivotal role in pulmonary complications after oesophagectomy. A lot of inflammatory mediators including interferon-gamma and granulocyte colony-stimulating factor are reported to modify the life span of polymorphonuclear leucocytes.

AIMS

In this study we investigated whether interferon-gamma and granulocyte colony-stimulating factor are associated with pulmonary complications after oesophagectomy.

PATIENTS AND METHODS

We measured interferon-gamma and granulocyte colony-stimulating factor concentrations in bronchoalveolar lavage fluid of 37 patients who had undergone oesophagectomy and examined the relationship between these mediators and pulmonary complications.

RESULTS

Pulmonary complications occurred in nine patients (24%, Pneum(+)). There was no significant difference in age, gender, preoperative comorbid conditions, tumour stage, operation method, operating time or blood loss between the Pneum(+) group and another 28 patients(Pneum(-)). Days until extubation were significantly increased in the Pneum(+) group than in the Pneum(-) group. Interferon-gamma (on postoperative day 2) and granulocyte colony-stimulating factor (on postoperative days 1-3) in bronchoalveolar lavage fluid were significantly increased in the Pneum(+) group than in the Pneum(-) group and granulocyte colony-stimulating factor was significantly correlated with days until extubation.

CONCLUSIONS

Our results indicate that bronchoalveolar lavage fluid granulocyte colony-stimulating factor is associated with respiratory conditions after oesophagectomy and assaying it can be useful for predicting pulmonary complications.

CT is useful for identifying patients with complicated appendicitis

BACKGROUND AND AIMS

We often come across patients with complicated appendicitis (perforation, abscess formation, or peritonitis) and it is essential to get accurate and detailed information on these patients preoperatively. In this study, we investigated whether or not preoperative computed tomography is useful for identifying these patients.

PATIENTS AND METHODS

Plain and intravenously-contrasted helical computed tomography was obtained preoperatively in 94 (75%) of 125 patients who underwent appendectomy. Twenty-eight (30%) of the 94 patients had complicated appendicitis (Compli(+) group). We compared clinical factors and computed tomography findings of the Compli(+) group with those of 66 other patients (Compli(-) group).

RESULTS

There was no significant difference between the Compli(+) and Compli(-) groups in gender, white blood cell count, the present rate of an enlarged appendix, or appendicolith. Fat stranding and free fluid on computed tomography were significantly associated with complicated appendicitis by both univariate and multilogistic regression analysis. Fourteen (70%) of the 20 patients with fat stranding and free fluid on computed tomography had complicated appendicitis and only 1 (4%) of the 28 Compli(+) patients had neither fat stranding nor free fluid on computed tomography.

CONCLUSION

Our study has indicated that fat stranding and free fluid on computed tomography are significant for complicated appendicitis and helical computed tomography is a powerful tool for identifying patients with complicated appendicitis preoperatively.

FAK overexpression is correlated with tumour invasiveness and lymph node metastasis in oesophageal squamous cell carcinoma

Focal adhesion kinase (p125(FAK); 'FAK') is a tyrosine kinase that is localised to cellular focal adhesions and is associated with a number of other proteins, such as integrin adhesion receptors. We performed an immunohistochemical analysis of FAK protein expression to determine the relationship between FAK overexpression and clinicopathological factors in oesophageal squamous cell carcinoma (ESCC). We examined tissue specimens that had been removed from 91 patients with thoracic oesophageal cancer who had undergone surgery between 1983 and 2001. Immunohistochemical staining was performed by the standard streptavidin-biotin method. Seven human ESCC cell lines-TE-1, TE-2, TE-8, TE-13, TE-15, TT, and TTn-and one immortalized human keratinocyte cell line-HaCaT-were used in Western blot analysis. Immunostaining of FAK was seen in the cytoplasm of cancer cells, particularly in cells located in the invasive fronts of cancer nests. FAK overexpression was detected in 54 of the 91 patients (59.3%). Significant correlations were observed between FAK overexpression and cell differentiation (P=0.0057), depth of tumour invasion (P=0.0023), presence of regional lymph node metastasis (P=0.0097), number of lymph node metastases (P=0.0026), and disease stage (P=0.012). The survival rates of patients with FAK-overexpressing cancer were significantly lower than those of patients without FAK-overexpression cancer (P=0.006). The 5-year survival rate of patients without FAK overexpression was 69%, whereas that of patients with FAK overexpression was 38%. On Western blot analysis, FAK was expressed at a high level in TE-1, TE-8, TE-15, and TT cells, at a moderate level in TE-2 and TTn cells, and at a low level in TE13 and HaCaT cells. FAK phosphorylation at tyrosine 397 was demonstrated in proportion to the intensity of FAK in all cell lines except TE15 and HaCaT. In conclusion, FAK overexpression of ESCC was related to cell differentiation, tumour invasiveness, and lymph node metastasis. Consequently, patients with ESCC who had FAK overexpression had a poor prognosis.

Identification and characterization of a novel Golgi protein, GCP60, that interacts with the integral membrane protein giantin

We demonstrated previously that the integral membrane protein giantin has the Golgi localization signal at the COOH-terminal cytoplasmic domain (Misumi, Y., Sohda, M., Tashiro, A., Sato, H., and Ikehara, Y. (2001) J. Biol. Chem. 276, 6867-6873). In the present study, using this domain as bait in the yeast two-hybrid screening system, we identified a novel protein interacting with giantin. The 3.6-kilobase mRNA encoding a 528-amino acid protein of 60 kDa designated GCP60 was ubiquitously expressed and was especially abundant in the testis and ovary. Immunofluorescence and immunoelectron microscopy confirmed that GCP60 was co-localized with giantin in the Golgi complex. GCP60 was found to be a peripheral protein associated with the Golgi membrane, where a COOH-terminal domain of GCP60 interacts with the COOH-terminal cytoplasmic domain of giantin. Overexpression of the COOH-terminal domain of GCP60 caused disassembly of the Golgi structure and blocked protein transport from the endoplasmic reticulum to the Golgi. Taken together, these results suggest that GCP60 is involved in the maintenance of the Golgi structure by interacting with giantin, affecting protein transport between the endoplasmic reticulum and the Golgi.

An essential cytoplasmic domain for the Golgi localization of coiled-coil proteins with a COOH-terminal membrane anchor

Giantin is a resident Golgi protein that has an extremely long cytoplasmic domain (about 370 kDa) and is anchored to the Golgi membrane by the COOH-terminal membrane-anchoring domain (CMD) with no luminal extension. We examined the essential domain of giantin required for Golgi localization by mutational analysis. The Golgi localization of giantin was not affected by the deletion of its CMD or by substitution with the CMD of syntaxin-2, a plasma membrane protein. The giantin CMD fused to the cytoplasmic domain of syntaxin-2 could not retain the chimera in the Golgi apparatus. Sequential deletion analysis showed that the COOH-terminal sequence (positions 3059--3161) adjacent to the CMD was the essential domain required for the Golgi localization of giantin. We also examined two other Golgi-resident proteins, golgin-84 and syntaxin-5, with a similar membrane topology as giantin. It was confirmed that the cytoplasmic domain of about 100 residues adjacent to the CMD was required for their Golgi localization. Taken together, these results suggest that the COOH-terminally anchored Golgi proteins with long cytoplasmic extensions have the Golgi localization signal(s) in the cytoplasmic sequence adjacent to the CMD. This is in contrast to previous observations that a transmembrane domain is required for Golgi localization by other Golgi proteins transported from the endoplasmic reticulum.

Maternal uniparental disomy for chromosome 14 in a boy with intrauterine growth retardation

Maternal uniparental disomy (UPD) for chromosome 14 [upd(14)mat] may cause a characteristic phenotype with growth and developmental deficiency and precocious puberty. We report the case of a Japanese infant with an isochromosome 14 [i(14q)] and intrauterine growth retardation (IUGR). The infant is one of triplets comprising a boy (the patient) and two karyotypically normal girls. We analyzed parent-child transmission modes of alleles on the i(14q) at 17 CA-repeat marker loci along the entire length of chromosome 14. Genotypes at 4 proximal and 5 distal loci on the i(14q) were consistent with maternal isodisomy, whereas those at an intervening region indicated maternal heterodisomy. Thus, the derivative chromosome 14 had arisen through a translocation between maternal homologous chromosomes 14 [t(14;14)(p10;q10)] after at least two crossing-over events at the first meiosis. This result also suggests that there must be maternally imprinted gene(s) on 14q, and that loss of the functionally active, paternally derived allele in the same locus may lead to IUGR. Alternatively, IUGR may be an autosomal recessive trait. In the latter case, the mother would be a heterozygote and the putative disease locus would be either at the most proximal or most distal region of 14q.

[Identification of aneuploids in uncultured amniotic fluid cells by interphase fluorescence in situ hybridization]

We report the diagnosis of aneuploids in uncultured amniotic fluid cells by the use of interphase fluorescence in situ hybridization (FISH). About a dozen of cases was studied to detect chromosome aneuploids (trisomies 13, 18 and 21, and monosomy X), especially those in the perinatal period. Results of FISH experiments in each specimen were compared with those of conventional chromosome analysis, and showed no discrepancy between them in most cases. FISH analysis revealed that four 18-trisomies had two different cells, one of which showed two fluorescence signals and the other three signals, the result indicating a maternal cell contamination. Thus, special attention should be paid when FISH analysis is adopted to the diagnosis in uncultured amniotic fluid cells in order to avoid misdiagnosis that may originate in maternal cell contamination.

Phosphorylation of the vesicle docking protein p115 regulates its association with the Golgi membrane

The vesicle docking protein p115 was found to be phosphorylated in a cell cycle-specific manner; it was found phosphorylated in interphase but not in mitotic cells. During interphase, however, two forms of p115 were detected in the cells; the phosphorylated form was found exclusively in cytosol, whereas the unphosphorylated form was associated with membranes, mostly of the Golgi complex. The latter form was released from the membranes upon phosphorylation. Mutational analysis revealed that the phosphorylation site of p115 was the Ser942 residue in the C-terminal acidic domain. A mutant with a single substitution of Ser942 --> Ala markedly increased its association with the Golgi membrane. Another mutant with Ser942 --> Asp was able to associate with the membrane, although at a decreased level, indicating that the dissociation of p115 from the membrane is not simply due to the negative charge of phosphorylated Ser942. Taken together, these results suggest that the phosphorylation of Ser942 at the C-terminal acidic domain regulates the interaction of p115 with the Golgi membrane, possibly taking part in the regulatory mechanism of vesicular transport.

Identification and characterization of rat 364-kDa Golgi-associated protein recognized by autoantibodies from a patient with rheumatoid arthritis

Autoantibodies from a patient with rheumatoid arthritis recognized an antigen localized in the Golgi complex of various cells tested. The autoantibodies were used as a probe for screening rat NRK cDNA library, resulting in identification of an 11 kbp cDNA. The cDNA contained an open reading frame which encodes a 3,187-residue protein with a calculated mass of 364 kDa. The predicted protein, GCP364 (for a Golgi complex-associated protein of 364 kDa), was found to have no NH2-terminal signal sequence but a single hydrophobic domain at the COOH terminus and characteristically contain many coiled-coil domains with various sizes throughout the entire sequence. The identity of GCP364 with the autoantigen was confirmed by immunofluorescence and immunoblot analysis with the autoantibodies and anti-recombinant GCP364 produced in rabbits and by transfection/expression experiments. Search for the protein sequence data base revealed that GCP364 has 75% identity in amino acid sequence with human GCP372/giantin, indicating that it is a rat homolog of the latter. Immunogold electron microscopy showed that GCP364 was not detected on coated vesicles derived from the Golgi membrane, suggesting no involvement in the formation of transport vesicles. When cells were perforated and incubated with anti-GCP364 serum, the Golgi complex localized at perinuclear regions was dispersed into fragment-like structures as observed in nocodazole-treated cells. Taken together, these results suggest that GCP364 is anchored to the membrane by the COOH-terminal hydrophobic domain and has an extremely long cytoplasmic domain with coiled-coil structures, which may be involved in the formation and/or maintenance of the characteristic Golgi structure.

Molecular characterization of GCP170, a 170-kDa protein associated with the cytoplasmic face of the Golgi membrane

We have isolated a cDNA clone encoding a protein (designated GCP170) of 1530 amino acid residues with a calculated molecular mass of 170 kDa that is localized to the Golgi complex. Hydropathy analysis shows that GCP170 contains no NH2-terminal signal sequence nor a hydrophobic domain sufficient for participating in membrane localization. It is also predicted that GCP170 has characteristic secondary structures including an extremely long alpha-helical domain that likely forms a coiled-coil between non-coil domains at the NH2 and COOH termini, suggesting that the protein is organized as a globular head, a stalk, and a tail. Immunocytochemical observations revealed that GCP170 was localized to the Golgi complex and the cytoplasm, consistent with biochemical data indicating that the protein exits as a membrane-associated form and a soluble form. GCP170 was dissociated from the Golgi membrane in response to brefeldin A as rapidly as a coat protein complex of non-clathrin-coated vesicles (beta-COP, a subunit of coatomer), but did not co-localize with beta-COP on the Golgi membrane when examined by immunoelectron microscopy. The protein was detected as phosphorylated and unphosphorylated forms, of which the unphosphorylated form was more tightly associated with the Golgi membrane. When cells were extracted with 1% Triton X-100 under microtubule-stabilizing conditions, GCP170 remained in the cells in association with the Golgi complex. These results indicate that GCP170 is a peripheral membrane protein with a long coiled-coil domain that may be involved in the structural organization or stabilization of the Golgi complex.

Molecular cloning and sequence analysis of a human 372-kDA protein localized in the Golgi complex

Autoantibodies from a patient with chronic rheumatoid arthritis recognized an antigen localized in the Golgi complex of various cells from different tissues and species. The autoantibodies were used as a probe for screening human QGP-1 cDNA library, resulting in identification of a 10.3-kb cDNA. The cDNA insert contained an open reading frame which encodes a 3225-residue protein with a calculated mass of 372 kDa. The predicted protein was found to have no NH2-terminal signal sequence but a single hydrophobic domain at the COOH terminus. These results indicate that the 372-kDa antigen is cytoplasmically disposed and anchored to the Golgi membrane by the COOH-terminal hydrophobic domain.

Conversion of secretory proteins into membrane proteins by fusing with a glycosylphosphatidylinositol anchor signal of alkaline phosphatase

Placental alkaline phosphatase (PLAP) is initially synthesized as a precursor (proPLAP) with a C-terminal extension. We constructed a recombinant cDNA which encodes a chimeric protein (alpha GL-PLAP) comprising rat alpha 2u-globulin (alpha GL) and the C-terminal extension of PLAP. Two molecular species (25 kDa and 22 kDa) were expressed in the COS-1 cell transfected with the cDNA for alpha GL-PLAP. Only the 22 kDa form was labelled with both [3H]stearic acid and [3H]ethanolamine. Upon digestion with phosphatidylinositol-specific phospholipase C the 22 kDa form was released into the medium, indicating that this form is anchored on the cell surface via glycosylphosphatidylinositol (GPI). A specific IgG raised against a C-terminal nonapeptide of proPLAP precipitated the 25 kDa form but not the 22 kDa form, suggesting that the 25 kDa form is a precursor retaining the C-terminal propeptide. When a mutant alpha GL-PLAP, in which the aspartic acid residue is replaced with tryptophan at a putative cleavage/attachment site, was expressed in COS-1 cells, the 25 kDa precursor was the only form found inside the cell and retained in the endoplasmic reticulum, as judged by immunofluorescence microscopy. In vitro translation programmed with mRNAs coding for the wild-type and mutant forms of alpha GL-PLAP demonstrated that the C-terminal propeptide was cleaved from the wild-type chimeric protein, but not from the mutant one. This gave rise to the 22 kDa form attached with a GPI anchor, suggesting that GPI is covalently linked to the aspartic acid residue (Asp159) of alpha GL-PLAP. Taken together, these results indicate that the C-terminal propeptide of PLAP functions as a signal to render alpha GL a GPI-linked membrane protein in vitro and in vivo in cultured cells, and that the chimeric protein constructed in this study may be useful for elucidating the mechanism underlying the cleavage of the propeptide and attachment of GPI, which occur in the endoplasmic reticulum.

Sequence requirements for proteolytic cleavage of precursors with paired basic amino acids

When expressed in COS cells, human prorenin was secreted into the medium without being processed to an active renin. Co-expression of furin, a mammalian homologue of the yeast KEX2 gene product, did not affect proteolytic processing of prorenin. A mutant proreninR-4 constructed by site-directed mutagenesis of Pro (-4) to Arg was not cleaved by an endoprotease in the COS cell. However, proreninR-4 was detectably cleaved to yield the active renin upon co-transfection with furin DNA, indicating that Arg at position -4 is important for recognition and processing by furin in addition to the absolute requirement for paired basic amino acids. Another mutant precursor in which Leu (+1) of proreninR-4 was replaced with Ser was found to be much more efficiently processed than proreninR-4, regardless of co-expression of furin. The results suggest that not only a basic amino acid at position -4 but also Leu at position +1 significantly affect the processing of prorenin catalyzed by the COS cell endoprotease or furin.

[Study of 123I-IMP SPECT on diabetic patients]

The involvement of peripheral nerves and nerve roots often leads to neurological manifestations which have frequently been described in association with diabetes mellitus. Whether there is any specific involvement of the central nervous system in this process has yet to be determined. Recently, many reports have suggested that significant neurophysiologic abnormalities in the central nervous system can sometimes be found in diabetic patients. In order to accurately examine the existence of central nervous system involvement in patients with diabetes mellitus, comparisons of 123I-IMP (IMP) washout rates were made between normal adults (n = 19, average age 43.3 years) and diabetic patients (n = 23, average age 43.3 years), and these results were graphically demonstrated by color images. Early images were obtained 30 minutes after intravenous injection, while delayed images were made 4 hours after injection. The IMP washout rate was obtained by subtracting the values of the delayed image with the early image. The standard deviation (SD) of the IMP washout rate for each patient was compared to the averaged SD obtained from healthy adults. After calculating the deviation from SD levels of healthy adults, we made an image of the patient's IMP washout rates. These images were divided into seven degrees (I, II: normal, III, IV: borderline, V-VII: abnormal) and the ratio of each degree was expressed by a histogram in each cerebral hemisphere as the washout rate index. In 23 diabetic subjects, seven patients were found to be borderline while sixteen patients were abnormal. These impairments were not related either to the presence of diabetic neuropathies or the duration of disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective processing of proalbumin determined by site-specific mutagenesis

Rat proalbumin is cleaved at the dibasic pair Arg-Arg and converted into a mature form with Glu at the NH2 terminus. In the present study site-directed mutagenesis of the albumin cDNA was designed to generate proalbumin variants in which Glu1 was substituted with various amino acid residues. The expression plasmids constructed were transfected into COS-1 cells, and the intracellular processing of proalbumins expressed was examined by labeling experiments. Substitution of Glu1----Ser allowed the expressed proalbumin to be processed as observed for the wild-type precursor. However, replacement of Glu1 with a hydrophobic residue (Val, Leu or Ile) resulted in no processing of proalbumin, despite retaining the same cleavage signal Arg-Arg as above. The results indicate that the residue at position 1 adjacent to the dibasic pair is also important for recognition by the proalbumin-processing enzyme.

Intracellular processing of complement pro-C3 and proalbumin is inhibited by rat alpha 1-protease inhibitor variant (Met352----Arg) in transfected cells

Complement C3, when its cDNA was transfected into COS-1 cells, was synthesized as a precursor, pro-C3, which was intracellularly processed into the alpha and beta subunits, although not completely. A cDNA for rat alpha 1-protease inhibitor (alpha 1-PI) was mutated in vitro to encode its variant with the modified active site (Met352----Arg). In cells co-transfected with the mutant alpha 1-PI cDNA and the C3 cDNA, pro-C3 expressed was secreted without being processed into the subunits. Co-transfection of the mutant alpha 1-PI cDNA and the albumin cDNA also resulted in the inhibition of intracellular conversion of proalbumin into serum-type albumin. No inhibition of the processing of each preform was observed in cells co-transfected with the normal alpha 1-PI cDNA. Taken together, the results indicate that the alpha 1-PI variant (Met352----Arg) expressed inhibits specifically an intracellular enzyme which is involved in the proteolytic processing of both pro-C3 and proalbumin.

Molecular cloning and sequencing of the cDNA of rat alpha 1-protease inhibitor and its expression in COS-1 cells

A cDNA clone for alpha 1-protease inhibitor (pc alpha 1P1212) was isolated from a lambda ZAP rat liver cDNA library. The 1.4 kb cDNA insert of pc alpha 1P1212 contained an open reading frame that encodes a 411-residue polypeptide (46,125 Da), in which a signal peptide of 24 residues was identified by comparison with the NH2-terminal sequence of the purified protein. Three potential sites for N-linked glycosylation were found in the molecule, accounting for the difference in molecular mass between the predicted form and the purified protein (56 kDa). The deduced primary structure of rat alpha 1-protease inhibitor showed 68.5% homology to that of the human inhibitor. We then constructed the expression plasmid pSV2 alpha 1PI from pSV2-gpt and pc alpha 1P1212, and transfected it into COS-1 cells. The transfected cells synthesized a molecule which was precipitated with anti-(rat alpha 1-protease inhibitor)-IgG and had the same molecular size as that of the inhibitor produced by rat hepatocytes.

A further improved method for identifying heteromorphism of acrocentric chromosomes

An improved method for identifying an individual heteromorphic acrocentric chromosome, a high-resolution dual Q-R banding, is described. The acrocentrics of 550-850 band-stage prometaphase showed more distinct fluorescent heteromorphic patterns at their paracentromeric regions than those of 400 band-stage metaphase. In the two families studied, all four (two pairs of) parental prometaphase homologues in every kind of acrocentric except chromosome 22 were clearly distinguished from each other, leading to accurate determination of the parental origin of all the children's acrocentric chromosomes. The dual Q-R banding on metaphase plates could distinguish at most three of four such homologues of the parents in both families. Several possible applications of this method are discussed.

Sensitive enzyme immunoassay for the quantification of aclacinomycin A using beta-D-galactosidase as a label

A sensitive enzyme immunoassay method (EIA) for an anticancer drug, aclacinomycin A (ACM), has been developed. With a double-antibody technique, ACM at a concentration as low as 100 pg/tube can be detected. An antibody to ACM was obtained by immunizing rabbits with an antigen prepared by coupling ACM with mercaptosuccinylated bovine serum albumin via N-maleoyl aminobutyric acid (MABA) as a coupling agent. Enzyme labeling of ACM was performed with beta-D-galactosidase (beta-Gal; EC 3.2.1.23) via m-maleoyl benzoic acid (MBA). The standard curve of the assay was linear on a logit-log plot over a concentration range of 30 pg to 10 ng. The antibody detected ACM and its metabolites, MA144 M1 (M1), MA144 N1 (N1), MA144 S1 (S1), and aklavin (T1) equally well, but was only minimally reactive with aklavinone (D1) and 7-deoxyaklavinone (C1), thus suggesting that this EIA can detect the total amounts of ACM and its biologically active glycosides among metabolites of ACM. This EIA is practically free from interference by any other anticancer drugs. Using this assay, serum levels of ACM equivalents can be determined accurately after administration of the drug to rats at a single dose of 10 mg/kg. Since ACM is now undergoing clinical trial, the EIA of the drug will be a valuable tool in clinical pharmacological studies.

Preparation of polyamine antibody and its use in enzyme immunoassay of spermine and spermidine with beta-D-galactosidase as a label

An enzyme immunoassay for polyamines is described which uses beta-galactosidase labeled spermine and antiserum raised in rabbits against spermine-bovine serum albumin synthesized by coupling spermine to mercaptosuccinylated bovine serum albumin with a bifunctional cross-linker, N-(gamma-maleimidobutyryloxy)-succinimide. The lower limit of detection by this assay, which involves a double antibody technique for the separation of antibody-bound and free antigen, was 1 ng of spermine per tube. The anti-spermine serum showed 88% cross-reaction with spermidine but only 0.13% with putrescine, 0.08% with 1,3-diaminopropane, and 0.04% with cadaverine. The method has been used to measure serum polyamine levels in healthy subjects and cancer patients, in whom mean concentrations of 58.1 ng/ml and 94.8 ng/ml (as spermine), were respectively noted. This enzyme immunoassay is specific, accurate and easy to perform, and appears suitable for routine clinical use.