ATF6 activated by proteolysis binds in the presence of NF-Y (CBF) directly to the cis-acting element responsible for the mammalian unfolded protein response

Transcription of genes encoding molecular chaperones and folding enzymes in the endoplasmic reticulum (ER) is induced by accumulation of unfolded proteins in the ER. This intracellular signaling, known as the unfolded protein response (UPR), is mediated by the cis-acting ER stress response element (ERSE) in mammals. In addition to ER chaperones, the mammalian transcription factor CHOP (also called GADD153) is induced by ER stress. We report here that the transcription factor XBP-1 (also called TREB5) is also induced by ER stress and that induction of CHOP and XBP-1 is mediated by ERSE. The ERSE consensus sequence is CCAAT-N(9)-CCACG. As the general transcription factor NF-Y (also known as CBF) binds to CCAAT, CCACG is considered to provide specificity in the mammalian UPR. We recently found that the basic leucine zipper protein ATF6 isolated as a CCACG-binding protein is synthesized as a transmembrane protein in the ER, and ER stress-induced proteolysis produces a soluble form of ATF6 that translocates into the nucleus. We report here that overexpression of soluble ATF6 activates transcription of the CHOP and XBP-1 genes as well as of ER chaperone genes constitutively, whereas overexpression of a dominant negative mutant of ATF6 blocks the induction by ER stress. Furthermore, we demonstrated that soluble ATF6 binds directly to CCACG only when CCAAT exactly 9 bp upstream of CCACG is bound to NF-Y. Based on these and other findings, we concluded that specific and direct interactions between ATF6 and ERSE are critical for transcriptional induction not only of ER chaperones but also of CHOP and XBP-1.

Overexpression of protein disulfide isomerase DsbC stabilizes multiple-disulfide-bonded recombinant protein produced and transported to the periplasm in Escherichia coli

Dsb proteins (DsbA, DsbB, DsbC, and DsbD) catalyze formation and isomerization of protein disulfide bonds in the periplasm of Escherichia coli. By using a set of Dsb coexpression plasmids constructed recently, we analyzed the effects of Dsb overexpression on production of horseradish peroxidase (HRP) isozyme C that contains complex disulfide bonds and tends to aggregate when produced in E. coli. When transported to the periplasm, HRP was unstable but was markedly stabilized upon simultaneous overexpression of the set of Dsb proteins (DsbABCD). Whereas total HRP production increased severalfold upon overexpression of at least disulfide-bonded isomerase DsbC, maximum transport of HRP to the periplasm seemed to require overexpression of all DsbABCD proteins, suggesting that excess Dsb proteins exert synergistic effects in assisting folding and transport of HRP. Periplasmic production of HRP also increased when calcium, thought to play an essential role in folding of nascent HRP polypeptide, was added to the medium with or without Dsb overexpression. These results suggest that Dsb proteins and calcium play distinct roles in periplasmic production of HRP, presumably through facilitating correct folding. The present Dsb expression plasmids should be useful in assessing and dissecting periplasmic production of proteins that contain multiple disulfide bonds in E. coli.

Prevalence of microalbuminuria and relationship to the risk of cardiovascular disease in the Japanese population

The prevalence of microalbuminuria and its relationship to cardiovascular disease risk factors were examined in subjects participating in an annual physical and laboratory examination program. The urinary albumin concentration and the urinary albumin/creatinine ratio were determined in morning urine specimens. A turbidimetric immunoassay was used for the measurement of urinary albumin. Of the 731 subjects, 41 (5.6%) who were weakly positive or positive on a routine dipstick test for protein were excluded from the final analysis of data. Microalbuminuria was present in 14.5% of the men, in 12.4% of the women, and in 13.2% of the entire subject population when defined as a urinary albumin concentration of 30-299 microgram/ml. The prevalence of microalbuminuria was significantly higher in subjects with a high normal blood pressure (15.0%) or hypertension (26.2%) as compared with normotensive subjects (6.5%). Subjects with impaired glucose tolerance (24.3%) or hyperglycemic subjects (50.0%) had a significantly higher prevalence of microalbuminuria than normoglycemic subjects (11.3%). The prevalence of microalbuminuria was significantly higher in subjects with left ventricular hypertrophy (47.1%) as compared with those with normal electrocardiograms (11.3%). A good correlation was observed between urinary albumin concentration and albumin/creatinine ratio, and both showed a significant positive correlation with age, systolic and diastolic blood pressures, and fasting plasma glucose, total serum protein, albumin, and triglyceride levels, but not with angiotensin-converting enzyme activity. Multiple regression analysis demonstrated that both the urinary albumin concentration and the albumin/creatinine ratio show a significant positive correlation with systolic blood pressure and fasting plasma glucose. The prevalence of microalbuminuria was about 13% in this Japanese cohort, and the systolic blood pressure and the fasting plasma glucose level were demonstrated as independent risk indicators for both urinary microalbumin level and urinary microalbumin/creatinine ratio.

A comparison of stapled and hand-sewn anastomoses in Crohn's disease

Sixty-eight patients with Crohn's disease who underwent intestinal resection were randomly divided into 2 groups: the stapled group (32 patients, 40 anastomoses) with functional end-to-end anastomoses made with linear staplers and with circular stapling anastomoses, and the hand-sewn group (36 patients, 48 anastomoses), with anastomoses achieved by layer-to-layer suturing. There were no significant differences in operative indications, age, sex, blood loss, or length of hospital stay between the groups. The operation times for right hemicolectomy and total colectomy in the stapled group were significantly shorter than those in the hand-sewn group. There were no significant differences in anastomotic dehiscence or recurrence between the stapling and hand-sewn procedures. These results indicate that these stapling techniques, even though producing an everted anastomosis, are not an adverse procedure for Crohn's disease.

Pentanucleotide repeat and size polymorphisms in the apolipoprotein(a) gene are associated with the lipoprotein(a) concentration in chronic hemodialysis patients

The elevation of serum or plasma lipoprotein(a) [Lp(a)] levels is regarded as an independent risk factor for cardiovascular disease, and many previous reports demonstrated that Lp(a) levels in hemodialysis patients were significantly higher than in controls. The purpose of this study was to investigate the effect of a pentanucleotide repeat polymorphism [(TTTTA)n] in the 5'-flanking region of the apolipoprotein(a) [apo(a)] gene and of a size polymorphism of apo(a) for elevated Lp(a) concentrations observed in chronic hemodialysis patients. We studied 172 patients on chronic hemodialysis and 199 healthy adults. For analysis of the pentanucleotide repeat polymorphism, polymerase chain reaction products were loaded on polyacrylamide gel for electrophoresis. apo(a) size phenotyping was performed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. The median level of Lp(a) in the patients was 14.2 mg/dl which was significantly higher than that in controls (12.0 mg/dl; p < 0.05). In the genotype of (TTTTA)8/8, the median Lp(a) level in the patients (15.9 mg/dl) was significantly higher than that in controls (13.0 mg/dl; p < 0.05). In the genotype of (TTTTA)8/8 with large-sized apo(a) isoforms (A16-A25), the patients had significantly higher Lp(a) levels than the controls (p < 0.05). In conclusion, increased Lp(a) levels in chronic hemodialysis patients were mainly attributed to the combination of eight repeats of the pentanucleotide polymorphism and large-sized isoforms of apo(a).

The effectiveness of preoperative intraluminal brachytherapy in preventing wall penetration and nodal involvement of rectal carcinomas

A retrospective review was conducted of 115 patients with middle or lower rectal carcinoma, without distant metastasis, who were consecutively treated with preoperative intraluminal brachytherapy and radical surgery (IBT group). Another 115 rectal carcinoma patients treated with surgery alone were reviewed as a control (NIBT group). We investigated whether conventional pathologic stagings were correlated with prognosis. All tumors were diagnosed by the TNM classification. According to the distribution of pathologic staging in the resected specimens, the prevalence of totally ablated tumors (stage T0) in the IBT group was significantly higher than that in the NIBT group, but there were no significant differences in the distribution of other T stages between the two groups. Good local control was achieved for the stage-T3 tumors in the IBT group, similarly to the T < or = 2 tumors in both groups. In the IBT group, the survival period of the patients with stage-T4 tumors even after radiotherapy was significantly shorter than that of those with T3 tumors (P = 0.042), while those with N < or = 2-stage tumors had significantly longer survival periods than those with N3-stage tumors (P = 0.047). These findings demonstrate the usefulness of analyzing clinicopathologic parameters to predict local control and the prolongation of survival. Determining these factors will also help to identify high-risk patients likely to require more effective adjuvant chemotherapy.

150-kDa oxygen-regulated protein (ORP150) functions as a novel molecular chaperone in MDCK cells

To assess the participation of the 150-kDa oxygen-regulated protein (ORP150) in protein transport, its function in Madin-Darby canine kidney (MDCK) cells was studied. Exposure of MDCK cells to hypoxia resulted in an increase of ORP150 antigen and increased binding of ORP150 to GP80/clusterin (80-kDa glycoprotein), a natural secretory protein in this cell line. In ORP150 antisense transformant MDCK cells, GP80 was retained within the endoplasmic reticulum after exposure to hypoxia. Metabolic labeling showed the delay of GP80 maturation in antisense transformants in hypoxia, whereas its matured form was detected in wild-type cells, indicating a role of ORP150 in protein transport, especially in hypoxia. The affinity chromatographic analysis of ORP150 suggested its ability to bind to ATP-agarose. Furthermore, the ATP hydrolysis analysis showed that ORP150 can release GP80 at a lower ATP concentration. These data indicate that ORP150 may function as a unique molecular chaperone in renal epithelial cells by facilitating protein transport/maturation in an environment where less ATP is accessible.

Dynamic interplay between antagonistic pathways controlling the sigma 32 level in Escherichia coli

The heat-shock response in Escherichia coli depends primarily on the transient increase in the cellular level of heat-shock sigma factor final sigma(32) encoded by the rpoH gene, which results from both enhanced synthesis and transient stabilization of normally unstable final sigma(32). Heat-induced synthesis of final sigma(32) was previously shown to occur at the translation level by melting the mRNA secondary structure formed within the 5' coding sequence of rpoH including the translation initiation region. The subsequent decrease in the final sigma(32) level during the adaptation phase has been thought to involve both shutoff of synthesis (translation) and destabilization of final sigma(32)-mediated by the DnaK-DnaJ chaperones, although direct evidence for translational repression was lacking. We now show that the heat-induced synthesis of final sigma(32) does not shut off at the translation level by using a reporter system involving translational coupling. Furthermore, the apparent shutoff was not observed when the synthesis rate was determined by a very short pulse labeling (15 s). Examination of final sigma(32) stability at 10 min after shift from 30 to 42 degrees C revealed more extreme instability (t(1/2)=20 s) than had previously been thought. Thus, the dynamic change in final sigma(32) stability during the heat-shock response largely accounts for the apparent shutoff of final sigma(32) synthesis observed with a longer pulse. These results suggest a mechanism for maintaining the intricate balance between the antagonistic pathways: the rpoH translation as determined primarily by ambient temperature and the turnover of final sigma(32) as modulated by the chaperone (and presumably protease)-mediated autogenous control.

mRNA splicing-mediated C-terminal replacement of transcription factor Hac1p is required for efficient activation of the unfolded protein response

Eukaryotic cells control the levels of molecular chaperones and folding enzymes in the endoplasmic reticulum (ER) by a transcriptional induction process termed the unfolded protein response (UPR) according to the needs within the ER. In Saccharomyces cerevisiae, expression of the UPR-specific transcription factor Hac1p is tightly regulated at the level of mRNA splicing that depends on an unconventional system. Thus, HAC1 precursor mRNA is constitutively expressed but not translated. A sensor molecule Ire1p/Ern1p-mediated signaling from the ER specifically removes an intron of 252 nucleotides from the precursor mRNA, and the resulting mature mRNA is translated to produce Hac1p. Because the 5' splice site is located near the C-terminal end of the Hac1p-coding region, this splicing replaces the last 10 codons of the ORF with an exon encoding 18 aa without affecting the N-terminal 220-aa region which contains the DNA-binding domain. Here, we found that this C-terminal 18-aa segment functions as a potent activation domain. Therefore, the splicing event joins the HAC1 DNA-binding domain to its activation domain, allowing rapid posttranscriptional generation of a potent transcriptional activator (238-aa Hac1p) that activates the UPR efficiently. This suggests that the UPR is hardly activated by Hac1p produced without splicing (230-aa Hac1p) which may occur in the absence of Ire1p/Ern1p-mediated signaling from the ER. Based on these and other results, we propose that the control of expression and activity of Hac1p meets the requirements of the ER.

Association of Trp64Arg polymorphism of the beta3-adrenergic receptor gene and no association of Gln223Arg polymorphism of the leptin receptor gene in Japanese schoolchildren with obesity

OBJECTIVE

To investigate whether Trp64Arg polymorphism of the beta3-adrenergic receptor (beta3-AR) gene and Gln223Arg polymorphism of the leptin receptor (Ob-R) gene are associated with obesity in Japanese schoolchildren.

DESIGN

Population study of participants from a rural town located within 50 km northeast of Tokyo based on school medical examinations.

SUBJECTS

553 Japanese schoolchildren (291 boys and 262 girls) who were 9-15 y old with a mean age of 11.9 +/- 1.8 y.

MEASUREMENTS

DNA was extracted from whole blood and genotyped by PCR-RFLP. Height, weight and blood pressure were measured in school medical examinations. Total cholesterol, triglyceride and HDL-cholesterol concentrations were measured by an autoanalyzer. Obesity index, body mass index (BMI) and LDL-cholesterol concentration were calculated by the respective formulae.

RESULTS

In Trp64Arg polymorphism of the beta3-AR gene, the number of obese subjects with Trp/Arg or Arg/Arg genotypes was significantly higher than that of the non-obese subjects (chi2=5.79, P=0.02). The obesity index of subjects with the Arg/Arg or Arg/Trp genotype was significantly higher than that of those with the Trp/Trp genotype (8.2 +/- 18.7% vs 4.5 +/- 15.8%, P=0.04). Moreover, after adjustments for age and gender, BMI of subjects with the Trp/Arg or Arg/Arg genotype was significantly higher than that of those with the Trp/Trp genotype (19.4 +/- 3.6 kg/m2 vs 18.9 +/- 3.2 kg/m2, P= 0.02). However, no significant differences were observed in the clinical characteristics among the genotype groups of the Ob-R gene.

CONCLUSIONS

Trp64Arg polymorphism of the beta3-AR gene appears to be a genetic risk factor for obesity in Japanese children, but Gln223Arg polymorphism of the Ob-R gene does not appear to be associated with obesity.

Upregulation of cytosolic chaperonin CCT subunits during recovery from chemical stress that causes accumulation of unfolded proteins

The chaperonin containing TCP-1 (CCT) is a molecular chaperone consisting of eight subunit species and assists in the folding of actin, tubulin and some other cytosolic proteins. We examined the stress response of CCT subunit proteins in mammalian cultured cells using chemical stressors that cause accumulation of unfolded proteins. Levels of CCT subunit proteins in HeLa cells were coordinately and transiently upregulated under continuous chemical stress with sodium arsenite. CCT subunit levels in several mammalian cell lines were also upregulated during recovery from chemical stress caused by sodium arsenite or a proline analogue, L-azetidine-2-carboxylic acid. Several unidentified proteins that were newly synthesized and associated with CCT were found to increase concomitantly with CCT subunits themselves and known substrates during recovery from the stress. These results suggest that CCT plays important roles in the recovery of cells from protein damage by assisting in the folding of proteins that are actively synthesized and/or renatured during this period.

Effects of elemental diet (ED) on surgical treatment in Crohn's disease

BACKGROUND/AIMS

Patients with Crohn's disease are at risk of developing short bowel syndrome if they are treated with repeated operations. We examined the effect of preoperative nutritional therapy with elemental diet on the interval until and the outcome after surgical treatment in patients with Crohn's disease.

METHODOLOGY

We reviewed the records for 73 patients with Crohn's disease who underwent intestinal resection in our department between January 1, 1974 and December 31, 1996. Thirty-two of them had not received elemental diet (No ED group) and 41 had received elemental diet therapy (ED group) before the first resection.

RESULTS

The median interval between the onset and first resection was 19.3 months for the NoED group and 67.5 months for the ED group (P = 0.0005). All patients received ED therapy after the first resection. The incidence of second resection was significantly different between the ED and the NoED group after the first operation. (P = 0.045).

CONCLUSIONS

Elemental diet therapy is effective in prolonging the interval between the onset and first resection and in reducing the incidence of second resection. The initial introduction of elemental diet therapy is useful in the management of the clinical course of Crohn's disease minimizing surgical intervention.

Overexpression of trigger factor prevents aggregation of recombinant proteins in Escherichia coli

To examine the effects of overexpression of trigger factor (TF) on recombinant proteins produced in Escherichia coli, we constructed plasmids that permitted controlled expression of TF alone or together with the GroEL-GroES chaperones. The following three proteins that are prone to aggregation were tested as targets: mouse endostatin, human oxygen-regulated protein ORP150, and human lysozyme. The results revealed that TF overexpression had marked effects on the production of these proteins in soluble forms, presumably through facilitating correct folding. Whereas overexpression of TF alone was sufficient to prevent aggregation of endostatin, overexpression of TF together with GroEL-GroES was more effective for ORP150 and lysozyme, suggesting that TF and GroEL-GroES play synergistic roles in vivo. Although coexpression of the DnaK-DnaJ-GrpE chaperones was also effective for endostatin and ORP150, coexpression of TF and GroEL-GroES was more effective for lysozyme. These results attest to the usefulness of the present expression plasmids for improving protein production in E. coli.

A new type of glycoglycerolipids from Corynebacterium aquaticum

A new type of glycoglycerolipids, S361A and S365A, were obtained from Corynebacterium aquaticum strains, S361 and S365, newly isolated from soils, and were identified as (2R)-1-[alpha-glucopyranosyl-(1alpha-3)-(6O-acyl-alpha-manno pyranosyl)]-3-O-acylglycerol and (2R)-1-[alpha-mannopyranosyl-(1alpha-3)-(6-O-acyl-alpha-mannopyran osyl)]-3-O-acylglycerol, respectively. S365A was identical to a novel glycoglycerolipid recently isolated from some bacteria, but S361A was a new analog having a glucosylmannosyl in place of the dimannosyl group. Our results indicate that this sn-2 lysotype of glyceroglycolipids may be widely distributed in bacteria.

Abundant expression of 150-kDa oxygen-regulated protein in mouse pancreatic beta cells is correlated with insulin secretion

The 150-kDa oxygen-regulated protein (ORP150) is a member of glucose-regulated proteins (GRPs), which are induced by stressful conditions such as oxygen or glucose deprivation. Here we investigated the highly abundant expression of ORP150 in mouse pancreas and its relationship with insulin secretion. Immunohistochemical analysis revealed that ORP150 expression was restricted to islets, especially to beta cells. The beta cell-specific expression was also observed in a mouse insulinoma cell line, MIN6, which secretes insulin in response to increased glucose concentration. Furthermore, ORP150 in islets dramatically diminished by fasting, concomitant with reduction of the serum insulin level. These results strongly suggest the role for ORP150 in insulin secretion.

Cytosolic chaperonin is up-regulated during cell growth. Preferential expression and binding to tubulin at G(1)/S transition through early S phase

The chaperonin containing t-complex polypeptide 1 (CCT) is a heterooligomeric molecular chaperone assisting in the folding of actin, tubulin, and other cytosolic proteins. The expression levels of CCT subunits varied among seven mouse cell lines tested but showed a close correlation with growth rate. Both the CCT protein and mRNA levels in the human promyelolytic cell HL60 decreased concomitant with growth arrest during differentiation. More rapid decrease in CCT level occurred when the mouse interleukin (IL)-3-dependent myeloid DA3 cells were starved for IL-3. Readdition of IL-3 caused rapid resumption of CCT synthesis during synchronous growth: the maximum CCT protein and mRNA levels were observed at G(1)/S transition through early S phase. The turnover rate of CCT was nearly constant regardless of growth. Gel filtration and immunoprecipitation analyses indicated that CCT in vivo is associated with tubulin at early S phase, but not at G(0)/G(1) phase. These results demonstrated that CCT expression is strongly up-regulated during cell growth especially from G(1)/S transition to early S phase and is primarily controlled at the mRNA level. CCT appears to play important roles for cell growth by assisting in the folding of tubulin and other proteins.

Differential and independent roles of a sigma(32) homolog (RpoH) and an HrcA repressor in the heat shock response of Agrobacterium tumefaciens

The heat shock response in alpha proteobacteria is unique in that a combination of two regulators is involved: a positive regulator, RpoH (sigma(32) homolog), found in the alpha, beta, and gamma proteobacteria, and a negative regulator, HrcA, widely distributed in eubacteria but not in the gamma proteobacteria. To assess the differential roles of the two regulators in these bacteria, we cloned the hrcA-grpE operon of Agrobacterium tumefaciens, analyzed its transcription, and constructed deletion mutants lacking RpoH and/or HrcA. The DeltarpoH mutant and DeltarpoH DeltahrcA double mutant were unable to grow above 30 degrees C. Whereas the synthesis of heat shock proteins (e.g., DnaK, GroEL, and ClpB) was transiently induced upon temperature upshift from 25 to 37 degrees C in the wild type, such induction was not observed in the DeltarpoH mutant, except that GroEL synthesis was still partially induced. By contrast, the DeltahrcA mutant grew normally and exhibited essentially normal heat induction except for a higher level of GroEL expression, especially before heat shock. The DeltarpoH DeltahrcA double mutant showed the combined phenotypes of each of the single mutants. The amounts of dnaK and groE transcripts before and after heat shock, as determined by primer extension, were consistent with those of the proteins synthesized. The cellular level of RpoH but not HrcA increased significantly upon heat shock. We conclude that RpoH plays a major and global role in the induction of most heat shock proteins, whereas HrcA plays a restricted role in repressing groE expression under nonstress conditions.

Transcriptional activation of mouse cytosolic chaperonin CCT subunit genes by heat shock factors HSF1 and HSF2

The chaperonin containing TCP-1 (CCT) is a eukaryotic molecular chaperone consisting of eight subunit species and assists in the folding of cytosolic proteins. We show here that all eight mouse CCT subunit genes contain sequences called heat shock elements for binding heat shock transcription factors (HSFs) by electrophoretic mobility shift assays and that these genes are transcriptionally activated by HSFs in reporter gene assays using HeLa cells transiently overexpressing HSFs. These results suggest that HSF1 and/or HSF2 play a role in Cct gene expression.

Mammalian transcription factor ATF6 is synthesized as a transmembrane protein and activated by proteolysis in response to endoplasmic reticulum stress

The unfolded protein response (UPR) controls the levels of molecular chaperones and enzymes involved in protein folding in the endoplasmic reticulum (ER). We recently isolated ATF6 as a candidate for mammalian UPR-specific transcription factor. We report here that ATF6 constitutively expressed as a 90-kDa protein (p90ATF6) is directly converted to a 50-kDa protein (p50ATF6) in ER-stressed cells. Furthermore, we showed that the most important consequence of this conversion was altered subcellular localization; p90ATF6 is embedded in the ER, whereas p50ATF6 is a nuclear protein. p90ATF6 is a type II transmembrane glycoprotein with a hydrophobic stretch in the middle of the molecule. Thus, the N-terminal half containing a basic leucine zipper motif is oriented facing the cytoplasm. Full-length ATF6 as well as its C-terminal deletion mutant carrying the transmembrane domain is localized in the ER when transfected. In contrast, mutant ATF6 representing the cytoplasmic region translocates into the nucleus and activates transcription of the endogenous GRP78/BiP gene. We propose that ER stress-induced proteolysis of membrane-bound p90ATF6 releases soluble p50ATF6, leading to induced transcription in the nucleus. Unlike yeast UPR, mammalian UPR appears to use a system similar to that reported for cholesterol homeostasis.

Current trends in restorative proctocolectomy: introduction of an ultrasonically activated scalpel

PURPOSE

We evaluated the usefulness of an ultrasonically activated scalpel (Harmonic Scalpel) for mucosal proctocolectomy and ileal J-pouch-anal anastomosis.

METHODS

Seventy-four patients with ulcerative colitis (70 patients) and familial adenomatous polyposis (4 patients) underwent mucosectomy using the Harmonic Scalpel since 1997. We compared the clinical and functional results with those of the monopolar electrocoagulator (forceps coagulation technique, 86 patients with colitis and 7 with polyposis).

RESULTS

We performed graduated mucosal proctectomy by using the Harmonic Scalpel. The operative time (Harmonic Scalpel, 42 minutes vs. forceps coagulation technique, 85 minutes) and blood loss (Harmonic Scalpel, 33 ml vs. forceps coagulation technique, 86.8 ml) were significantly reduced by this method. The Harmonic Scalpel enabled restorative proctocolectomy by the synchronous approach within three hours. The functional results and complications were not significantly different between the two groups.

CONCLUSION

The Harmonic Scalpel shortened the operative time, decreased blood loss, and was useful for restorative proctocolectomy in our study.

Association between serotonin transporter gene polymorphism and smoking among Japanese males

The serotoninergic system may be involved in smoking behavior because nicotine increases brain serotonin secretion, nicotine withdrawal decreases serotonin levels, and a selective serotonin reuptake inhibitor antagonizes the response to nicotine. Compared with the L allele, the S allele of the polymorphism in the upstream regulatory region of the serotonin transporter gene is associated with decreased transcription efficiency of the 5-HTT gene promoter. We examined this polymorphism in a Japanese population consisting of 387 males from two different areas in Japan. The L allele was observed significantly more often in smokers (21%) than in nonsmokers (lifetime nonsmokers + ex-smokers, 14%; P = 0.005). The presence of the L allele (the L/L + L/S genotypes) was also significantly increased in smokers (37%) compared with that in nonsmokers (24%; P = 0.003). The present study suggests that individuals with the S/S genotype are less inclined to smoke and/or can more easily stop smoking than others, supporting a role of the serotoninergic system in smoking behavior.

Marked instability of the sigma(32) heat shock transcription factor at high temperature. Implications for heat shock regulation

The heat shock response in Escherichia coli depends on a transient increase in the intracellular level of sigma(32) that results from both increased synthesis and transient stabilization of normally unstable sigma(32). Although the membrane-bound ATP-dependent protease FtsH (HflB) plays an important role in degradation of sigma(32), our previous results suggested that several cytosolic ATP-dependent proteases including HslVU (ClpQY) are also involved in sigma(32) degradation (Kanemori, M., Nishihara, K., Yanagi, H., and Yura, T. (1997) J. Bacteriol. 179, 7219-7225). We now report on the ATP-dependent proteolysis of sigma(32) by purified HslVU protease and its unusual dependence on high temperature: sigma(32) was rapidly degraded at 44 degrees C, but with much slower rates ( approximately 15-fold) at 35 degrees C. FtsH-dependent degradation of sigma(32) also gave similar results. In agreement with these results in vitro, the turnover of sigma(32) in normally growing cells at high temperature (42 degrees C) was much faster than at low temperature (30 degrees C). Taken together with other evidence, these results suggest that the sigma(32) level during normal growth is primarily determined by the stability (susceptibility to proteases) and synthesis rate of sigma(32) set by ambient temperature, whereas fine adjustment such as transient stabilization of sigma(32) observed upon heat shock is brought about through monitoring changes in the cellular state of protein folding.

Structures and co-regulated expression of the genes encoding mouse cytosolic chaperonin CCT subunits

The chaperonin-containing TCP-1 (CCT) is a hetero-oligomeric molecular chaperone that mediates protein folding in the cytosol of eukaryotes. Eight (or nine in testis) subunit species are assembled in the CCT hexadecamer complex. We have cloned seven CCT subunit genes, Cctb, Cctd, Ccte, Cctz-1, Cctz-2 (testis specific), Ccth and Cctq, from mouse genomic DNA libraries, in addition to the Ccta and Cctg genes reported previously, and the entire nucleotide sequences of these DNA clones were determined. These genes are approximately 15-20 kb in length except for Cctz-2 which is longer than 35 kb, and all the Cct genes consist of 11-16 exons. Primer extension analyses of testis RNA indicate one to several potential transcription start sites 50-150 bp upstream from the translation start codon of each Cct gene. There are several possible Sp1-binding sequences, but no obvious TATA box was observed around the potential start sites. From 5'-flanking regions to the first introns, the Cct genes are rich in CpG dinucleotides. In reporter gene assays using these regions, five of eight Cct genes showed strong transcriptional activity comparable with the combination of SV40 promoter and enhancer in HeLa cells. We also show, by Western and Northern blot analyses, that CCT expression levels vary widely among different tissues but the expression patterns are very similar among the eight subunit species. It is likely that expression levels of the eight different subunits are tightly co-regulated to maintain a constant ratio of these subunits which constitute the CCT hexadecamer complex with a fixed subunit arrangement.

The ATP-dependent HslVU/ClpQY protease participates in turnover of cell division inhibitor SulA in Escherichia coli

Escherichia coli mutants lacking activities of all known cytosolic ATP-dependent proteases (Lon, ClpAP, ClpXP, and HslVU), due to double deletions [DeltahslVU and Delta(clpPX-lon)], cannot grow at low (30 degrees C) or very high (45 degrees C) temperatures, unlike those carrying either of the deletions. Such growth defects were particularly marked when the deletions were introduced into strain MG1655 or W3110. To examine the functions of HslVU and other proteases further, revertants that can grow at 30 degrees C were isolated from the multiple-protease mutant and characterized. The revertants were found to carry a suppressor affecting either ftsZ (encoding a key cell division protein) or sulA (encoding the SulA inhibitor, which binds and inhibits FtsZ). Whereas the ftsZ mutations were identical to a mutation known to produce a protein refractory to SulA inhibition, the sulA mutations affected the promoter-operator region, reducing synthesis of SulA. These results suggested that the growth defect of the parental double-deletion mutant at a low temperature was due to the accumulation of excess SulA without DNA-damaging treatment. Consistent with these results, SulA in the double-deletion mutant was much more stable than that in the Delta(clpPX-lon) mutant, suggesting that SulA can be degraded by HslVU. As expected, purified HslVU protease degraded SulA (fused to the maltose-binding protein) efficiently in an ATP-dependent manner. These results suggest that HslVU as well as Lon participates in the in vivo turnover of SulA and that HslVU becomes essential for growth when the Lon (and Clp) protease level is reduced below a critical threshold.