Tag-mediated isolation of yeast mitochondrial ribosome and mass spectrometric identification of its new components

Mitochondrial ribosomal proteins (mrps) of the budding yeast, Saccharomyces cerevisiae, have been extensively characterized genetically and biochemically. However, the list of the genes encoding individual mrps is still not complete and quite a few of the mrps are only predicted from their similarity to bacterial ribosomal proteins. We have constructed a yeast strain in which one of the small subunit proteins, termed Mrp4, was tagged with S-peptide and used for affinity purification of mitochondrial ribosome. Mass spectrometric analysis of the isolated proteins detected most of the small subunit mrps which were previously identified or predicted and about half of the large subunit mrps. In addition, several proteins of unknown function were identified. To confirm their identity further, we added tags to these proteins and analyzed their localization in subcellular fractions. Thus, we have newly established Ymr158w (MrpS8), Ypl013c (MrpS16), Ymr188c (MrpS17) and Ygr165w (MrpS35) as small subunit mrps and Img1, Img2, Ydr116c (MrpL1), Ynl177c (MrpL22), Ynr022c (MrpL50) and Ypr100w (MrpL51) as large subunit mrps.

MCM3-binding GANP DNA-primase is associated with a novel phosphatase component G5PR

BACKGROUND

GANP, carrying DNA-primase and MCM3-binding domains, is up-regulated in germinal centre B cells. To understand the regulatory function of GANP upon MCM complex, we searched for GANP-associated molecules by yeast two-hybrid screening.

RESULTS

Using the 1 kb fragment (G5) of the ganp cDNA, we identified a clone named G5PR that is structurally homologous to known regulatory subunits of protein phosphatases (PPases) and determined the association of G5PR with GANP in vivo in the DNA transfectant. G5PR is associated with protein phosphatase 5 (PP5) through its tetratricopeptide-repeat (TPR) domain. Pull-down assays demonstrated that G5PR is also associated with protein phosphatase 2A (PP2A), the complex of A subunit (PR65) and the catalytic (C) subunit (PP2Ac), similar to the B" subunit. The G5PR-associated complex had phosphatase activity on casein, histone H1 and MCM3 in vitro, but the addition of G5PR did not stimulate or inhibit the phosphatase activities of PP5 and PP2A. The cellular localization of G5PR in transfected cells varies during cell cycling, appearing in the nucleus during prophase, in the peri-chromatin during mitotic phase, and in the cytoplasm after cell division.

CONCLUSION

G5PR is capable of recruiting two kinds of PPases, PP5 and PP2A, into the GANP/MCM3 complex, which might regulate its phosphorylation state during cell cycle progression.

Raptor, a binding partner of target of rapamycin (TOR), mediates TOR action

mTOR controls cell growth, in part by regulating p70 S6 kinase alpha (p70alpha) and eukaryotic initiation factor 4E binding protein 1 (4EBP1). Raptor is a 150 kDa mTOR binding protein that also binds 4EBP1 and p70alpha. The binding of raptor to mTOR is necessary for the mTOR-catalyzed phosphorylation of 4EBP1 in vitro, and it strongly enhances the mTOR kinase activity toward p70alpha. Rapamycin or amino acid withdrawal increases, whereas insulin strongly inhibits, the recovery of 4EBP1 and raptor on 7-methyl-GTP Sepharose. Partial inhibition of raptor expression by RNA interference (RNAi) reduces mTOR-catalyzed 4EBP1 phosphorylation in vitro. RNAi of C. elegans raptor yields an array of phenotypes that closely resemble those produced by inactivation of Ce-TOR. Thus, raptor is an essential scaffold for the mTOR-catalyzed phosphorylation of 4EBP1 and mediates TOR action in vivo.

Proteome and transcriptome analysis of the virulence genes regulated by the VirR/VirS system in Clostridium perfringens

The proteins under the control of the two-component system VirR/VirS in Clostridium perfringens were analyzed by using two-dimensional gel electrophoresis of the culture supernatant from the wild type and the virR mutant. Based on matrix-assisted laser desorption ionization-time of flight/mass spectrometry, seven positively regulated proteins and eight negatively regulated proteins were identified. Transcriptome analysis confirmed that 7 of the 15 proteins were regulated by the VirR/VirS system at the transcriptional level, but the remaining proteins were modified with a VirR/VirS-directed protease at the posttranslation and secretion levels. We purified and characterized the VirR/VirS-directed protease from the culture supernatant and identified it as a kind of clostripain. Because this proteolytic activity was strongly inhibited by leupeptin and antipain, it was concluded that this protease was a member of the family of cysteine proteases of C. perfringens.

Characterization of ubiquilin 1, an mTOR-interacting protein

The mTOR protein kinase is known to control cell cycle progression and cell growth through regulation of translation, transcription, membrane traffic and protein degradation. Known interactions of mTOR do not account for the multiple functions of this protein. Using a non-catalytic segment of mTOR (1-670) as bait in a yeast two-hybrid screen for interacting proteins, ubiquilin 1 (NM013438) was identified. Ubiquilin 1 is a member of a phylogenetically conserved gene family of unknown function, characterized by an N-terminal ubiquitin-like (Ubq) domain, a C-terminal ubiquitin associated (Uba) domain and a central region containing numerous NPXvar phi motifs (X, any; phi, hydrophobic amino acid). GST-ubiquilin 1 binds specifically to FLAG-mTOR (residues 1-670) in mammalian cells; residues 570-670 of mTOR and 226-323 of ubiquilin 1 are required for this interaction. Both mTOR and ubiquilin immunoreactivity appear as fine speckles throughout the cytoplasm; significant colocalization with cytoskeletal elements, early endosomes or proteasomes is not observed. As assessed by cell fractionation, mTOR is predominantly associated with low density membranes, along with 10% of ubiquilin 1. Ubiquilin 1 is a rapamycin-insensitive phosphoprotein. Overexpression of ubiquilin 1 does not alter the kinase activity of cotransfected mTOR or the phosphorylation of the mTOR target, p70 S6 kinase, in the presence or absence of rapamycin. Our data suggest that we have identified a novel mTOR interactor, ubiquilin 1. The biological significance of this, presumably membrane based, interaction, requires further study.

Brain-derived neurotrophic factor enhances neuronal translation by activating multiple initiation processes: comparison with the effects of insulin

The effects of neurotrophic factors on translational activation were investigated in cortical neurons. Brain-derived neurotrophic factor (BDNF) increased protein synthesis within 30 min, whereas insulin produced a weaker enhancement of protein synthesis. BDNF-triggered protein synthesis was inhibited by LY294002, PD98059, and rapamycin, whereas the effect of insulin was unaffected by PD98059. To explore the mechanisms underlying this effect, the protein phosphorylation cascades that lead to the activation of translation initiation in neurons were examined. BDNF induced the phosphorylation of both eukaryote initiation factor (eIF) 4E and its binding protein (eIF4E-binding protein-1). The former reaction was inhibited by PD98059, whereas the latter was inhibited by LY294002 or rapamycin. In agreement, BDNF induced the phosphorylation of mammalian TOR (target of rapamycin) and enhanced its kinase activity toward eIF4E-binding protein-1. In contrast, insulin failed to activate MAPK and did not induce the phosphorylation of eIF4E. Since BDNF and insulin increased the activity of eIF2B and eIF2, the only difference between them was eIF4E phosphorylation. Thus, this may explain the lower activity of insulin in potentiating neuronal protein synthesis. These results suggest strongly that BDNF simultaneously activates multiple signaling cascades consisting of phosphatidylinositol 3-kinase, mammalian TOR, and MAPK to enhance translation initiation in neurons.

Distinct regulatory mechanism for p70 S6 kinase beta from that for p70 S6 kinase alpha

BACKGROUND

A novel ribosomal S6 kinase, termed p70 S6 kinase beta (p70beta), has a highly homologous amino acid sequence to that of p70/p85 S6 kinase (p70alpha). This includes the critical phosphorylation sites, Thr252, Ser394 and Thr412 in p70alpha1, which correspond to Thr241, Ser383 and Thr401 in p70beta1, respectively. However, the regulatory mechanism for p70beta remains to be elucidated.

RESULTS

We report here the expression and the mechanism of in vivo regulation of p70beta. Two isoforms, p70beta1 and p70beta2, were expressed in a variety of tissues at a different level. p70beta1 was mainly targeted to the nucleus, whereas p70beta2 dispersed throughout the cytoplasm including nucleoplasm. The kinase activity of p70beta1 was less sensitive to the inhibition induced by rapamycin, wortmannin and amino acid withdrawal than that of p70alpha. The portion of p70beta activity inhibited by rapamycin was rescued by the rapamycin-resistant mutant of the mammalian target of rapamycin (mTOR). Mutational analysis revealed that the phosphorylation of Thr241 and Thr401 in p70beta1 was indispensable for the kinase activity. In contrast, a p70beta1 mutant in which Ser383 was substituted with Gly (S383G) still retained nearly the half maximal activity. Sequential phosphorylation of wild-type and S383G mutant of p70beta1 with mTOR and 3-phosphoinositide-dependent protein kinase 1 (PDK1) in vitro synergistically activated their kinase activities.

CONCLUSION

These results indicate that p70beta is regulated by the mTOR- and PDK1-signalling pathways through a synergistic interaction between phosphorylated Thr241 and Thr401, while Ser383 plays minor role in their activation mechanism. Activated p70beta may be less sensitive to dephosphorylation mediated by putative phosphatases activated by rapamycin, amino acid withdrawal, and probably wortmannin.

Suppression of tumor necrosis factor-alpha production and neutrophil infiltration during ischemia-reperfusion injury of the liver after heat shock preconditioning

BACKGROUND/AIMS

Heat shock preconditioning provides the liver with ischemic tolerance. In this study we examined the effects of heat shock preconditioning on hepatic nonparenchymal cells in light of tumor necrosis factor-alpha (TNF-alpha) production and neutrophil infiltration.

METHODS

Rats were exposed to heat shock pretreatment at 42 degrees C in the heat shock group (group HS) and at 37 degrees C in the control group (group C). After a 48-h recovery, the left hepatic lobes were given a 90-min ischemia and reperfused. Plasma concentrations of TNF-alpha, cytokine-induced neutrophil chemoattractant (CINC) and alanine aminotransferase (ALT) were measured. Liver tissues were checked for the presence of TNF-alpha mRNA. Histological staining for CINC and polymorphonuclear leukocyte (PMN) was also evaluated.

RESULTS

In group HS, plasma TNF-alpha levels were significantly more suppressed than in group C (P<0.0001). Expressions of TNF-alpha mRNA in the liver was suppressed in group HS. Production of CINC 2 h after reperfusion was reduced in group HS (P<0.05). PMN infiltration was significantly reduced in group HS (P<0.01). In group HS, liver histology revealed less cellular damage and the plasma level of ALT was significantly reduced (P<0.0001).

CONCLUSIONS

Heat shock preconditioning suppressed the production of TNF-alpha and CINC in the liver during reperfusion and consequently reduced neutrophil infiltration.

Expression patterns of the erbB subfamily mRNA in canine benign and malignant mammary tumors

ErbB subfamily genes, known as proto-oncogenes, encode receptor tyrosine kinases, and are expressed in relation to tumorigenesis of the mammary gland in humans. In this study, we examined the expression of erbB subfamily mRNAs in two canine normal mammary glands and 12 mammary tumor samples by reverse transcriptase-coupled polymerase chain reaction (RT-PCR). Each primer set was designed from the nucleotide sequence of the region conserved in erbB subfamily cDNA among other species. No erbB subfamily mRNAs were expressed in the normal mammary gland. In contrast, all of the subfamily mRNAs were expressed in a benign mammary tumor, and more than one type of the subfamily mRNA were observed in 11 malignant mammary tumors. The length of RT-PCR products were 380 bp for erbB1, 500 bp for erbB2, 644 bp for erbB3, and 416 bp for erbB4. These sequences were highly homologous to the cDNA sequences of other species. Therefore, these results suggest that the expression of erbB subfamily mRNAs in canine mammary tumors plays an important role in tumorigenesis of the mammary gland.

The elusive benzocyclobutenylidene: a combined computational and experimental attempt

Ab initio and density functional theory calculations predict that benzocyclobutenylidene (1) has a singlet ground state in contrast to the parent phenylcarbene and many other simply substituted arylcarbenes. Calculations also predict that 1 should lie in a relatively deep potential well, while its triplet state is 14.5 kcal mol(-)(1) higher in energy. However, attempts to observe 1 directly by photolysis of two different nitrogenous precursors were not successful. Irradiation of diazobenzocyclobutene (7) (lambda > 534 nm or lambda > 300 nm) or azibenzocyclobutene (10) (lambda > 328 nm) in Ar matrixes at 10 K leads to the formation of the strained cycloalkyne 7-methylenecyclohepta-3,5-dien-1-yne (3). (13)C-Labeled 3 was also prepared in a similar manner. There is very good agreement between experimental IR spectra and computationally derived harmonic vibrational frequencies for 3 and [(13)C]-3 and excellent agreement between observed and calculated isotopic shifts. Prolonged short-wavelength irradiation converts 3 into benzocyclobutadiene (5). Phenylacetylene (6) and benzocyclobutadiene dimer (11) were identified as products arising from flash vacuum pyrolysis of diazirine 10 at 500 degrees C.

Muscle high-energy metabolites and metabolic capacity in patients with heart failure

OKITA, K., K. YONEZAWA, H. NISHIJIMA, A. HANADA, T. NAGAI, T. MURAKAMI, and A. KITABATAKE. Muscle high-energy metabolites and metabolic capacity in patients with heart failure. Med Sci. Sports. Exerc., Vol. 33, No. 3, 2001, pp. 442-448.

BACKGROUND

Various abnormalities in skeletal muscle have been demonstrated by biopsy in patients with chronic heart failure (CHF). In mammalian muscles, high-energy metabolite composition at rest (HEMC) provides data on important metabolic characteristics; however, the significance of HEMC has not been clarified in patients with CHF. Therefore, we investigated HEMC in normal subjects and patients with CHF and examined its relation to muscle metabolic capacity and exercise tolerance.

METHODS

High-energy metabolites (phosphocreatine (PCr), inorganic phosphate (Pi), and ATP) in resting calf muscle were measured by 31P-magnetic resonance spectroscopy (31P-MRS), and ratios of Pi to PCr, Pi to ATP, and PCr to ATP were calculated in 34 patients with CHF and 13 age- and size-matched normal subjects. Muscle metabolism was evaluated during local exercise of unilateral plantar flexion by 31P-MRS. Metabolic capacity was estimated by the rate of PCr breakdown in relation to the workload. Systemic exercise capacity was evaluated by a bicycle ergometer.

RESULTS

The ratio of PCr to ATP was significantly increased in patients with CHF compared with controls (3.06 +/- 0.43 vs 2.72 +/- 0.36, P < 0.05) and was significantly correlated with metabolic capacity (r = -0.37, P < 0.01) and with peak oxygen uptake (r = -0.45, P < 0.01). There was a significant correlation between metabolic capacity and peak oxygen uptake (r = 0.53, P < 0.001).

CONCLUSION

HEMC was altered in patients with CHF, and this change was related to metabolic capacity and exercise capacity. These findings provide new insight into the mechanism of impaired muscle metabolism in CHF.

In situ pedicle resection in left trisegmentectomy of the liver combined with reconstruction of the right hepatic vein to an inferior vena caval segment transpositioned from the infrahepatic portion

A combination of an in situ pedicle resection of the liver and a hepatic vein reconstruction using a cranially transpositioned segment of the IVC after implantation of an ePTFE graft at the missing IVC was useful in treating a patient who suffered from a huge liver tumor involving all of the hepatic venous confluence and the IVC. Although early tumor recurrence remains an unresolved problem for such patients, a surgical approach is feasible. This technique can be justified as a therapeutic modality, not only because it improves quality of life, but also because it provides patients with an opportunity for additional treatment.

Formulation and estimation of the effective size of stage-structured populations in Fritillaria camtschatcensis, a perennial herb with a complex life history

The effective population size (Ne) is formulated based on a stage-structured population model and is estimated for two populations of Fritillaria camtschatcensis (L.) Ker-Gawl. (Liliaceae), a perennial, mainly clonally reproducing herb. Plants in these populations change life-history stages year by year, either upward or downward across three unambiguously identifiable stages: one-leaf, nonflowering; multileaf nonflowering; and multileaf, flowering stages. Plants of all stages produce clonal progeny (bulblets) each year, and death of plants occurs only in the first stage. The populations are nearly at equilibrium in both population size and stage structure. Ne is estimated to be 20-30% of the census population size (N), leading to the prediction that a population size of about 20,000 or more will be needed to conserve the normal level of the gene diversity (Ne > or = 5000). With the current demographic pattern of this species, accelerated growth of the first-stage plants with reduced survival of the second- and third-stage plants will increase both the annual (Ny/N) and generation time (Ne/N) effective sizes of population.

Definition of the probability efficiency index for optimization of the stepwise yield selection procedures of plant varieties

Equations to give exact predictions for the multistep yield selection in a finite population of plant varieties were defined. Not only the optimum resource allocation within a selection trial but also the optimum resource investment for a trial as a whole can be obtained based on the cost-efficiency index defined in this article.

[A case with juvenile rheumatoid arthritis who developed cerebral vasculitis and venovascular hypertension]

On November, 1997, a 15-year-old boy visited our hospital because of headache, fever and arthralgia. He was treated with 5 mg/day of prednisolone thereafter. On October 21, 1998, he was admitted because of remittent fever and multiple arthralgia and diagnosis of juvenile rheumatoid arthritis (JRA) was made. He was also found to have hypertension of 210/110 mmHg, and soon developed ptosis of the eye, facial paresis and perceptive deafness of the right side. Cerebrospinal fluid showed protein of 98 mg/dl and mildly elevated IgG, IgA and IgM levels with normal cell count. Brain MRI examination revealed multiple cerebral lesions in the frontal, parietal and cerebellar areas on the right, whose cause was thought to be vasculitis. Renal angiography demonstrated a right renal artery stenosis, compatible with renovascular hypertension. He was treated with 60 mg of prednisolone per day, which brought about a satisfactory improvement of the above rheumatic and neurologic signs. On November 17, 1998, he received a follow-up study of MRI, which failed to show any cerebral lesions, supporting the effectiveness of prednisolone. An angiotensin converting enzyme inhibitor successfully normalized hypertension and renin activity in serum, although renal blood flow did not increase.

Carboxyl-terminal region conserved among phosphoinositide-kinase-related kinases is indispensable for mTOR function in vivo and in vitro

BACKGROUND

The mammalian target of rapamycin (mTOR) belongs to the family of phosphoinositide (PI)-kinase-related kinases that includes the ataxia-telangiectasia gene product (ATM). mTOR plays a critical role in controlling translational effectors such as p70 S6 kinase alpha (p70 alpha) and eukaryotic initiation factor 4E binding protein 1 (4EBP1).

RESULTS

We show that the C-terminal region of mTOR, which is highly conserved among the PI-kinase-related kinases, plays a critical role in the mTOR protein kinase activity. Deletion of the C-terminal residues did not adversely affect the expression of mTOR, but caused a nearly complete loss of the mTOR protein kinase activity toward both 4EBP1 and p70 alpha in vitro. These deletions also abolished the ability of a rapamycin-resistant mTOR mutant to rescue the activity of p70 alpha from inhibition induced by rapamycin in vivo. Furthermore, replacement of Trp2545, a conserved residue in the C-terminal region throughout the PI-kinase-related kinase family, abolished the function of the mTOR kinase, both in vivo and in vitro. However, substitution of 32 C-terminal residues of mTOR with those of ATM did not restore the mTOR function.

CONCLUSIONS

These findings define an indispensable role for the noncatalytic C-terminal region of mTOR and indicate that, although this highly conserved region may be important throughout the PI-kinase-related kinase family, it is not functionally interchangeable within the family.

Effects of geranyl-geranyl-acetone administration before heat shock preconditioning for conferring tolerance against ischemia-reperfusion injury in rat livers

The effect of geranyl-geranyl-acetone (GGA) administration before heat shock preconditioning on heat shock protein (HSP) 72 induction and on the acquisition of tolerance against ischemia-reperfusion Injury was studied in rat livers. Male Wistar rats were divided into four groups: a control group (group C); a GGA group (group G); a simple heat shock group (group VH); and a heat shock with GGA premedication group (group GH). Five-, 10-, and 15-minute periods of heat shock preconditioning at 42 degrees C were performed in groups VH and GH. Subgroups were determined according to the period of heat shock exposure. After a 48-hour recovery, rats in groups C, VH5, VH15, and GH5 received a 30-minute period of hepatic ischemia. Induction of HSP72, survival rates, and changes in biochemical and histologic parameters were compared among the groups. Five-minute heat shock preconditioning was not enough to Induce HSP72. However, livers in group GH5 expressed approximately the same amount of HSP72 as those in group VH15. The expression of HSP72 in group GH15 was stronger than that found in group VH15. The degree and location of HSP72 expression were not different between groups GH5 and VH15. Seven-day survival was significantly better in groups GH5 (16/16) and VH15 (15/16) than in group C (8/16) or VH5 (9/16). The recovery of adenosine triphosphate in liver tissue was faster, and the release of liver-related enzymes during reperfusion was lower in groups GH5 and VH15 than in group C or VH5. Administration of GGA before heat shock preconditioning augmented the induction of HSP72 by decreasing the threshold for triggering the stress response.

Dissociation between muscle metabolism and oxygen kinetics during recovery from exercise in patients with chronic heart failure

OBJECTIVE

To estimate muscle metabolism and oxygen delivery to skeletal muscle in patients with chronic heart failure.

METHODS

13 patients with chronic heart failure and 15 controls performed calf plantar flexion for six minutes at a constant workload of 50% of one repetition maximum. During recovery from exercise, skeletal muscle content of oxygenated haemoglobin (oxy-Hb) and the level of phosphocreatine (PCr) were measured by near-infrared spectroscopy and (31)P-magnetic resonance spectroscopy, respectively.

RESULTS

The mean (SD) time constants of PCr and oxy-Hb during recovery from exercise were significantly greater in patients with chronic heart failure than in normal subjects (tau PCr: 76.3 (30.2) s v 36.5 (5.8) s; tau oxy-Hb: 48.3 (7.3) s v 30.1 (7.7) s; p < 0.01). Both time constants were similar in normal subjects, while the tau PCr was significantly greater than the tau oxy-Hb in patients with chronic heart failure.

CONCLUSIONS

The slower recovery of PCr compared with oxy-Hb in patients with chronic heart failure indicates that haemoglobin resaturation is not a major rate limiting factor of PCr resynthesis. It is suggested that muscle metabolic recovery may depend more on oxygen utilisation than on haemoglobin resaturation or oxygen delivery in patients with chronic heart failure.

Mammalian TOR controls one of two kinase pathways acting upon nPKCdelta and nPKCepsilon

There are three conserved phosphorylation sites in protein kinase C (PKC) isotypes that have been termed priming sites and play an important role in PKC function. The requirements and pathways involved in novel (nPKC) phosphorylation have been investigated here. The evidence presented for nPKCdelta shows that there are two independent kinase pathways that act upon the activation loop (Thr-505) and a C-terminal hydrophobic site (Ser-662) and that the phosphorylation of the Ser-662 site is protected from dephosphorylation by the Thr-505 phosphorylation. Both phosphorylations require C1 domain-dependent allosteric activation of PKC. The third site (Ser-643) appears to be an autophosphorylation site. The serum-dependent phosphorylation of the Thr-505 and Ser-662 sites increases nPKCdelta activity up to 80-fold. Phosphorylation at the Ser-662 site is independently controlled by a pathway involving mammalian TOR (mTOR) because the rapamycin-induced block of its phosphorylation is overcome by co-expression of a rapamycin-resistant mutant of mTOR. Consistent with this role of mTOR, amino acid deprivation selectively inhibits the serum-induced phosphorylation of the Ser-662 site in nPKCdelta. It is established that nPKCepsilon behaves in a manner similar to nPKCdelta with respect to phosphorylation at its C-terminal hydrophobic site, Ser-729. The results define the regulatory inputs to nPKCdelta and nPKCepsilon and establish these PKC isotypes downstream of mTOR and on an amino acid sensing pathway. The multiple signals integrated in PKC are discussed.

Immunopurified mammalian target of rapamycin phosphorylates and activates p70 S6 kinase alpha in vitro

p70 S6 kinase alpha (p70alpha) is activated in vivo through a multisite phosphorylation in response to mitogens if a sufficient supply of amino acids is available or to high concentrations of amino acids per se. The immunosuppressant drug rapamycin inhibits p70alpha activation in a manner that can be overcome by coexpression of p70alpha with a rapamycin-resistant mutant of the mammalian target of rapamycin (mTOR) but only if the mTOR kinase domain is intact. We report here that a mammalian recombinant p70alpha polypeptide, extracted in an inactive form from rapamycin-treated cells, can be directly phosphorylated by the mTOR kinase in vitro predominantly at the rapamycin-sensitive site Thr-412. mTOR-catalyzed p70alpha phosphorylation in vitro is accompanied by a substantial restoration in p70alpha kinase activity toward its physiologic substrate, the 40 S ribosomal protein S6. Moreover, sequential phosphorylation of p70alpha by mTOR and 3-phosphoinositide-dependent protein kinase 1 in vitro resulted in a synergistic stimulation of p70alpha activity to levels similar to that attained by serum stimulation in vivo. These results indicate that mTOR is likely to function as a direct activator of p70 in vivo, although the relative contribution of mTOR-catalyzed p70 phosphorylation in each of the many circumstances that engender p70 activation remains to be defined.

[Clinical aspects of ulcerative colitis with special reference to symptoms, signs and laboratory data]

Clinical aspects of 48 definite ulcerative colitis patients were investigated and compared to those with domestic and foreign reported cases. The disease was frequent in adults of 20-30 years of age. Bloody stool, diarrhea and abdominal pain were the major symptoms associated with slight anemia and signs and laboratory data of inflammation. Stresses seemed to evoke the onset of the disease. Persistent and watery diarrhea may indicate the diseased area of large intestine. Fever, high c-reactive protein value and the degree of abdominal pain was reflected by the severity of the disease.