Function of the propeptide region in recombinant expression of active procathepsin L in Escherichia coli

In order to determine the functional role of the procathepsin L propeptide region for the preparation of active recombinant rat cathepsin L (CL), cDNAs encoding two short-length propeptides (C-terminal 2 and 27 residues) and the full-length (96 residues) one plus the entire CL were expressed as two soluble fusion proteins with a fragment of maltose-binding protein and an insoluble fusion protein with glutathione-S-transferase in Escherichia coli, respectively. After refolding of the insoluble fusion protein, each gene product was purified to homogeneity by amylose or glutathione-Sepharose-4B affinity column, and digestion with factor Xa and alpha-thrombin under alkaline conditions (pH approximately 8.0) led to the elution of two pure short-length procathepsin Ls (PCLs) and a full-length one, respectively. The enzymatic activity, estimated by hydrolytic assaying of benzoxycarbonyl-Phe-Arg-7-(4-methyl)coumarylamide under acidic conditions (pH 5.5), indicated that the two short-length PCLs exhibited in a great loss of the activity, as compared with the full-length PCL. The CD spectra of the short-length PCLs were different from that of the full-length one. The present results clearly show that the full-length propeptide is essential for construction of the active tertiary structure of CL at the stage of recombinant protein expression, although the expression of CL itself in E. coli does not require the propeptide. Based on the tertiary structure of PCL, the propeptide region necessary for the construction of the CL active structure has been discussed.

Two divergent signaling pathways for TGF-beta separated by a mutation of its type II receptor gene

Transforming growth factor beta (TGF-beta) can inhibit epithelial cell growth and induce extracellular matrix formation through signal transduction via its two receptors and its downstream intracellular Smad proteins. We recently reported a germline mutation, i.e., substitution of methionine for threonine at codon 315 in the kinase subdomain IV, of the TGF-beta type II receptor gene in a kindred of hereditary nonpolyposis colorectal cancer without microsatellite instability and found that the mutant receptor abolished the signal transduction for growth inhibition by TGF-beta. In this study, we performed further functional analysis of this mutant receptor. The results showed that, in contrast to its failure to mediate growth inhibition by TGF-beta, the mutant receptor still retained the ability to induce one of the extracellular matrix proteins, plasminogen activator inhibitor type 1, upon TGF-beta treatment. However, coincident with its failure to mediate growth inhibition by TGF-beta, the mutant receptor failed to transcriptionally upregulate one of the cyclin-dependent kinase inhibitors, p15(INK4B), in response to TGF-beta. These data suggest that threonine 315 of the TGF-beta type II receptor is dispensable for extracellular matrix protein production, but is essential for the growth inhibition by TGF-beta, and that the lack of growth inhibition due to the mutant receptor is possibly mediated through its failure to upregulate p15(INK4B).

PQBP-1, a novel polyglutamine tract-binding protein, inhibits transcription activation by Brn-2 and affects cell survival

A novel gene, designated PQBP-1, which encodes a 265 residue protein that binds to the polyglutamine tract of the brain-specific transcription factor Brn-2, was identified. PQBP-1, which also interacts with the polyglutamine tract of triplet repeat disease gene products, binds with a higher affinity to an expanded polyglutamine tract. PQBP-1 has several functional domains, including hepta- and di-amino acid repeat sequences rich in polar residues essential for its interaction with the polyglutamine tract, a WWP/WW domain which binds to proline-rich motifs in other proteins, a putative nuclear localization signal sequence and a C2domain implicated in Ca2+-dependent phospholipid signaling. PQBP-1 is located in the nucleus and inhibits transcriptional activation by Brn-2. Overexpression of PQBP-1 in P19 embryonic carcinoma cells suppresses their growth rate and enhances their susceptibility to various stresses including serum deprivation, retinoic acid treatment and UV irradiation. Northern blot and in situ hybridization analyses revealed that PQBP-1 is a ubiquitous protein and is expressed primarily in neurons throughout the brain, with abundant levels in hippocampus, cerebellar cortex and olfactory bulb. These results suggest that PQBP-1 mediates important cellular functions under physiological and pathological conditions via its interaction with polyglutamine tracts.

The response of the slow atrioventricular nodal pathway to temperature

The present study attempted to determine the lowest temperature at which the slow atrioventricular nodal pathway responds to heating and the temperature necessary for successful ablation of the slow pathway in patients with atrioventricular nodal reentrant tachycardia (AVNRT). The study group comprised 23 consecutive patients (14 women, 9 men) with symptomatic AVNRT. Radiofrequency current was delivered at the slow pathway potential recording site using a HAT 200S catheter ablation system. Successful radiofrequency ablation of the slow pathway was achieved in all 23 patients. Junctional beats, suggesting the response of the slow pathway to temperature, were detected in 62 of the total 136 applications. The temperature measured at the first junctional beat was 45.4+/-4.2 degrees C. The maximum temperature required for the successful ablation of AVNRT ranged from 45 to 88 degrees C. There were no complications except for 1 patient with transient atrioventricular (AV) block. There were no recurrences of AVNRT during follow-up. The lowest temperature at which the slow pathway was responsive to heat was quite similar to that for accessory pathways or the AV junction. However, the temperature required for the successful ablation of AVNRT differed markedly among the patients.

Positive and negative modulation of vitamin D receptor function by transforming growth factor-beta signaling through smad proteins

Several lines of experiments demonstrated the interplay between the transforming growth factor-beta (TGF-beta) and vitamin D signaling pathways. Recently, we found that Smad3, a downstream component of the TGF-beta signaling pathway, potentiates ligand-induced transactivation of vitamin D receptor (VDR) as a coactivator of VDR (Yanagisawa, J., Yanagi, Y., Masuhiro, Y., Suzawa, M., Watanabe, M., Kashiwagi, K., Toriyabe, T., Kawabata, M., Miyazono, K., and Kato, S. (1999) Science 283, 1317-1321). Here, we investigated the roles of inhibitory Smads, Smad6 and Smad7, which are negative regulators of the TGF-beta/bone morphogenetic protein signaling pathway, on the Smad3-mediated potentiation of VDR function. We found that Smad7, but not Smad6, abrogates the Smad3-mediated VDR potentiation. Interaction studies in vivo and in vitro showed that Smad7 inhibited the formation of the VDR-Smad3 complex, whereas Smad6 had no effect. Taken together, our results strongly suggest that the interplay between the TGF-beta and vitamin D signaling pathways is, at least in part, mediated by the two classes of Smad proteins, which modulate VDR transactivation function both positively and negatively.

Successful treatment of refractory bronchorrhea by inhaled indomethacin in two patients with bronchioloalveolar carcinoma

Bronchorrhea in patients with bronchioloalveolar carcinoma is not uncommon. However, to our knowledge, an effective treatment for bronchorrhea in these patients has not been established. Recently, we have confirmed the efficacy of inhaled indomethacin in severe refractory bronchorrhea in comparison to that of other medications in two patients with bronchioloalveolar carcinoma. Despite the administration of a macrolide and corticosteroid, sputum volume increased to 700 mL/d in case 1 and to 200 mL/d in case 2 and hypoxemia and dyspnea deteriorated. Within a few days after the initiation of treatment with inhaled nebulized indomethacin (75 mg/d), sputum volume started to decrease and was controlled to < 100 mL/d, associated with alleviation of dyspnea and hypoxemia. To our knowledge, this is the first report of successfully treated refractory bronchorrhea associated with bronchioloalveolar carcinoma by inhaled indomethacin, resulting in markedly reduced sputum volume, improved quality of life, and prolonged survival.

Eosinophilic pneumonia with eosinophilic gastroenteritis

A 48-year-old man was admitted to our hospital with cough, fever and dysphagia. He had a past history of bronchial asthma and surgery for nasal polyp. Chest radiograph and computed tomography showed atelectasis in the right lower field and infiltrative shadow in the left lower field and overall thickening of the esophageal wall. Transbronchial lung biopsy (TBLB) specimens revealed infiltration of eosinophils and lymphocytes under the bronchial mucosa. Gastrointestinal tract biopsy specimens showed submucosal infiltration of eosinophils. These findings led to a definite diagnosis of eosinophilic pneumonia associated with eosinophilic gastroenteritis, a disease which has been rarely reported.

Evaluation of contrast agents for delineation of vessel wall boundary by intracoronary ultrasound after coronary angioplasty in human

We evaluated the potential for improving visualization at intervention sites using contrast-enhanced intracoronary ultrasound (ICUS) and the suitable contrast agents for this procedure in humans. In 37 patients, ICUS (30 MHz) was performed with intracoronary bolus injection (3 mL) of seven different contrast preparations and without the contrast agents (control) after coronary intervention. The contrast agents used were as follows: saline solution, standard iomeprol, standard ioxaglate, sonicated iomeprol, sonicated ioxaglate, 50% Albunex, and 100% Albunex. Homogeneous and complete opacification of the vessel lumen and false lumen was observed with sonicated ioxaglate, 50% and 100% Albunex. Shadowing was not observed at all with sonicated ioxaglate and was uncommon with 50% Albunex, whereas 100% Albunex caused shadowing in all cases. The coronary delineation rate with the other contrast agents was only 60%-70%, and the homogeneity and peak intensity were relatively low. Thus, sonicated ioxaglate and 50% Albunex both achieved good visualization, but the latter is more expensive, more difficult to handle, and takes longer to prepare. Of the agents we studied, sonicated ioxaglate appears to be best suited for contrast-enhanced ICUS. ICUS using suitable contrast agents could only visualize the large dissections and the strategy was changed according to the contrast-enhanced ICUS results in five cases. Thus, suitable contrast agents, e.g., sonicated ioxaglate, should be used during ICUS after intracoronary intervention.

Synergistic signaling in fetal brain by STAT3-Smad1 complex bridged by p300

The cytokines LIF (leukemia inhibitory factor) and BMP2 (bone morphogenetic protein-2) signal through different receptors and transcription factors, namely STATs (signal transducers and activators of transcription) and Smads. LIF and BMP2 were found to act in synergy on primary fetal neural progenitor cells to induce astrocytes. The transcriptional coactivator p300 interacts physically with STAT3 at its amino terminus in a cytokine stimulation-independent manner, and with Smad1 at its carboxyl terminus in a cytokine stimulation-dependent manner. The formation of a complex between STAT3 and Smad1, bridged by p300, is involved in the cooperative signaling of LIF and BMP2 and the subsequent induction of astrocytes from neural progenitors.

Multiple alternative transcripts of the human homologue of the mouse TRAD/R51H3/RAD51D gene, a member of the rec A/RAD51 gene family

Yeast RAD51, a homologue of Escherichia coli recA, plays a crucial role in mitotic and/or meiotic recombination and in the repair of double-strand DNA breaks. We have identified unique multiple alternative transcripts of a human TRAD/R51H3/RAD51D gene, a member of the recA/RAD51 gene family. One of the transcripts encoded a 328-amino-acid protein with 83.0% overall amino acid identity and 98. 2% similarity with the mouse TRAD gene and had two nucleotide binding consensus sequences, motif A and motif B, conserved among members of this family. Other transcripts encoded truncated proteins with a partial N-terminal region of the orthologue or short proteins lacking internal sequences which contain nucleotide binding motifs. Northern blot analysis revealed that multiple transcripts of the human TRAD gene were expressed in various tissues and their distribution was not ubiquitous.

Convergence of transforming growth factor-beta and vitamin D signaling pathways on SMAD transcriptional coactivators

Cell proliferation and differentiation are regulated by growth regulatory factors such as transforming growth factor-beta (TGF-beta) and the liphophilic hormone vitamin D. TGF-beta causes activation of SMAD proteins acting as coactivators or transcription factors in the nucleus. Vitamin D controls transcription of target genes through the vitamin D receptor (VDR). Smad3, one of the SMAD proteins downstream in the TGF-beta signaling pathway, was found in mammalian cells to act as a coactivator specific for ligand-induced transactivation of VDR by forming a complex with a member of the steroid receptor coactivator-1 protein family in the nucleus. Thus, Smad3 may mediate cross-talk between vitamin D and TGF-beta signaling pathways.

[Clinical investigation of 15 patients with pulmonary cryptococcosis--clinical comparison of HTLV-I carriers and non-carriers]

We investigated 15 pulmonary cryptococcosis patients. The group had a mean age of 51.7 years, and 6 (40%) of the patients were women. Cryptococcosis was primary in 13 patients and secondary in 2 (diabetes mellitus and smoldering adult T-cell leukemia). Eight patients were asymptomatic and 9 patients were detected by medical examinations. Dry cough was the most common symptoms. On chest radiographs, 5 patients showed solitary nodules, 4 patients showed infiltrative shadows, and 4 patients showed multiple nodules. The right lower lobe was the predominant location of solitary nodules, and the left upper and middle lung fields were the predominant locations of infiltrative shadows. Transbronchial lung biopsy was the method of diagnosis for 9 patients, and open lung biopsy for the others. Eleven patients were treated with fluconazole, and the mean treatment period was 7 months. Four patients underwent, resection procedures only, and experienced no recurrence. Five patients were positive for HTLV-I (one had smoldering ATL) and 5 were negative. Eighty percent of the HTLV-I positive patients had some symptoms and 80% of the HTLV-I negative patients were asymptomatic. HTLV-I positive patients showed various pulmonary shadows and 80% of the HTLV-I negative patients showed solitary nodules. The pulmonary lesions in HTLV-I positive patients were more extensive than those in HTLV-I negative patients (p < 0.05). We postulate the possible existence of subtle immunological abnormalities, including abnormalities of cellular immunity, in HTLV-I carriers.

Drosophila dSmad2 and Atr-I transmit activin/TGFbeta signals

BACKGROUND

Much is known about the three subfamilies of the TGFbeta superfamily in vertebrates-the TGFbetas, dpp/BMPs, and activins. Signalling in each subfamily is dependent on both shared and unique cell surface receptors and Smads. In invertebrates, mutants for BMP pathway components have been extensively characterized, but thus far, evidence for an activin- or TGFbeta-like pathway has been lacking, preventing the use of the extensive genetic tools available for studying several key issues of TGFbeta signalling.

RESULTS

Here we report the identification of dSmad2, a new Drosophila Smad which is most related to the activin/TGFbeta-pathway Smads, Smad2 and Smad3. We show that dSmad2 induces activin responsive genes in Xenopus animal cap assays. dSMAD2 is phosphorylated by ATR-I and PUNT, but not by activated THICK VEINS, and translocates to the nucleus upon activation. Furthermore, we show that dSMAD2 complexes with MEDEA only in the presence of ATR-I and PUNT. dSmad2 is expressed in the imaginal disks and in the outer proliferation centre of the larval brain, suggesting that it may have important proliferative and patterning roles during Drosophila development.

CONCLUSION

Our data provide evidence for the existence of an activin/TGFbeta pathway in Drosophila. We show that dSmad2 participates in this pathway, and that it functions with Atr-I and punt. We show that Medea also participates in this pathway, indicating the conservation of roles for Co-Smads in diverse phyla. Expression patterns of dSmad2 suggest that it functions in imaginal disks and in the brain, in tissues that undergo extensive patterning and proliferation.

Intermittent bundle branch blocks in a patient with uncommon-type atrioventricular nodal reentrant tachycardia and enhanced atrioventricular nodal conduction

We report on a patient with uncommon-type atrioventricular (AV) nodal reentrant tachycardia with a short tachycardia cycle length (235-270 ms), in whom transient wide QRS tachycardia with both left bundle branch block and right bundle branch block aberrancy were followed by narrow QRS complexes. In addition, His-ventricular (H-V) block and a sudden prolongation of the H-V interval occurred during the tachycardia. As the determinant of these unusual findings, the possibility that the anterograde limb of the reentry circuit has an enhanced AV nodal conduction property is discussed, as is the clinical significance of this type of tachycardia.

Signal transduction of the TGF-beta superfamily by Smad proteins

Members of the TGF-beta superfamily regulate the growth and differentiation of various types of cells. Smads are recently identified proteins that mediate intracellular signaling of the TGF-beta superfamily. Smads are grouped into three classes depending on their structure and functions. R-Smads are phosphorylated by type I serine-threonine kinase receptors for TGF-beta superfamily members. R-Smads then associate with Co-Smads. Smad4 is the only vertebrate Co-Smad identified thus far, and is required for the signaling pathways of different ligands. The heteromeric Smad complex translocates into the nucleus, where it activates target genes. Anti-Smads inhibit signaling by R-Smads and Co-Smads. Smads bind to DNA directly or indirectly via other DNA binding proteins. R-Smads interact with transcriptional coactivators, and have intrinsic transactivation activity. Elucidation of the functions of Smads will provide the framework for research on TGF-beta superfamily signaling.

Polar amino acid-rich sequences bind to polyglutamine tracts

Polyglutamine tracts are found in different proteins including transcription factors and cofactors as well as in triplet repeat disease gene products. To characterize the protein motif that binds to the polyglutamine tract, we screened a human embryonic brain cDNA library with the polyglutamine tract of Brn-2 as bait using the yeast two-hybrid method. All six isolated clones encoding polyglutamine tract binding proteins were rich in polar amino acids. Three of these clones could form polar helical structures. These observations suggest that polar amino acid-rich sequences are essential for binding to the polyglutamine tract.

Quantitative analysis of human multidrug resistance 1 (MDR1) gene expression by nonisotopic competitive reverse transcriptase polymerase chain reaction assay

We have established competitive reverse transcriptase polymerase chain reaction (RT-PCR) assay for the quantification of MDR1 mRNA encoding P-glycoprotein (P-gp) by analyzing leukemia sublines of MOLT-3 with various expression of MDR1. The expression was quantified by simultaneous RT-PCR of cellular RNA with decreasing amounts of heterologous competitor RNA, which shares the MDR1 primer sequences with the cellular MDR1 mRNA, but yields a different-sized PCR product. This allows resolution of the amplified cDNA fragments. The amounts of MDR1 mRNA measured by the assay were accurate and reproducible over wide range, and were determined as 31.6, 100, and 316 amol/microgram total RNA in MOLT-3/TMQ70, MOLT-3/ TMQ800, and MOLT-3/VCR1,000, respectively. The relative ratio of MDR1 mRNA measured by the competitive RT-PCR among three sublines was similar to that of MDR1 transcript determined by Northern analysis (1:4:12) and to that of P-gp measured by flow cytometry (FCM) analysis. In mononuclear cells from patients with leukemia, MDR1 mRNA could be sufficiently quantified by the competitive RT-PCR established, while FCM assay could scarcely detet P-gp. This study demonstrated that the competitive RT-PCR assay using heterologous competitor RNA is a rapid, reliable, and non-radioactive procedure and is acceptable for the evaluation of MDR1 expression in clinical samples.

New diagnostic finding to assess para-Hisian pacing observed in a patient with a permanent form of junctional reciprocating tachycardia

Para-Hisian pacing, a useful method to differentiate conduction over an accessory pathway from conduction over the AV node, is assessed essentially by comparing the timing of local atrial electrograms between His-bundle captured beats and His-bundle noncaptured beats. We describe the case of a patient with a permanent form of junctional reciprocating tachycardia, in whom an atrial double potential was recorded only during the tachycardia at the right posterior septum. During para-Hisian pacing, a morphologic change in the atrial electrogram at the posterior septum was also identified, as well as a change in the retrograde atrial sequence. Since the morphologic change of atrial electrograms during para-Hisian pacing cannot be demonstrated in a patient without an accessory pathway, this new finding could be considered a new additional diagnostic criterion suggesting the presence of an accessory pathway.

Pulmonary manifestations in cerebrotendinous xanthomatosis

We investigated five cases with cerebrotendinous xanthomatosis (CTX) with particular reference to biochemical and pathological pulmonary disorders. To date, few reports discuss the pathophysiology of pulmonary disorders of CTX patients. This study is the first investigation of such pulmonary disorders. All 5 patients had no pulmonary symptoms and no disturbances on radiological studies and pulmonary function tests. However, in bronchoalveolar lavage (BAL) fluids, many cells with cruciform reflexes, which is characteristic of intracellular sterol accumulation, were found under phase contrast microscopy. Biochemically, cholestanol was found to be increased in the BAL fluid as well as in serum. Pathological findings of transbronchial lung biopsy (TBLB) samples disclosed foamy macrophages and small granulomas in alveolar septa. In conclusion, the lung was apparently involved in CTX, and the lesions were characterized with the accumulation of foamy and giant cells with a high concentration of cholestanol, which likely results in the formation of foreign body granulomas.

Premature bifurcation of the apical dendritic trunk of vibrissa-responding pyramidal neurones of X-irradiated rat neocortex

1. Electrophysiological and morphological experiments were performed on the pyramidal neurones of the somatosensory neocortex of the adult rat that had been exposed in utero to 200 rad of X-irradiation. Under urethane anaesthesia, evoked gross potentials, extracellular and intracellular neuronal responses, and laminar field potentials were recorded. The evoked epicortical potential to deflection of a single whisker was a long-lasting positive wave which contrasted with a biphasic positive-negative complex in unirradiated controls. Neurones were initially tested during extracellular recording for responses to whisker deflections. This was followed by intracellular injection with horseradish peroxidase (HRP), and the HRP-stained neuronal elements were visualized using diaminobenzidine as a chromagen. 2. Fifty neurones were recorded and stained through the soma. The mean response latency was 15.1 ms. Of these, thirty-six showed premature bifurcation of the apical dendrite. The angle of bifurcation of the apical dendrite was measured in the coronal plane and was found to be a function of the depth at which the soma was located and the distance between the soma and bifurcation point. It was suggested that the apical dendrites of these neurones underwent premature bifurcation due to an imbalance between the growth of neurones and skull. 3. Fifteen neurones were recorded and stained through the presumed apical dendritic shaft. The mean response latency was 19.5 ms. The electrode track left in the histological specimen pointed to the stained apical dendrite. Dendritic elements distal to the entry point were preferentially filled with HRP. In no cases were somata stained. There was, in turn, no evidence of recording from dendritic elements distal to the bifurcation since no electrode track was found to point to these elements. That dendritic spike responses may not travel beyond the bifurcation was further substantiated by laminar analysis of field potentials.