Control of PHAS-I by insulin in 3T3-L1 adipocytes. Synthesis, degradation, and phosphorylation by a rapamycin-sensitive and mitogen-activated protein kinase-independent pathway

PHAS-I levels increased 8-fold as 3T3-L1 fibroblasts differentiated into adipocytes and acquired sensitivity to insulin. Insulin increased PHAS-I protein (3.3-fold after 2 days), the rate of PHAS-I synthesis (3-fold after 1 h), and the half-life of the protein (from 1.5 to 2.5 days). Insulin also increased the phosphorylation of PHAS-I and promoted dissociation of the PHAS-I eukaryotic initiation factor-4E (eIF-4E) complex, effects that were maximal within 10 min. With recombinant [H6]PHAS-I as substrate, mitogen-activated protein (MAP) kinase was the only insulin-stimulated PHAS-I kinase detected after fractionation of extracts by Mono Q chromatography; however, MAP kinase did not readily phosphorylate [H6]PHAS-I when the [H6]PHAS-I.eIF-4E complex was the substrate. Thus, while MAP kinase may phosphorylate free PHAS-I, it is not sufficient to dissociate the complex. Moreover, rapamycin attenuated the stimulation of PHAS-I phosphorylation by insulin and markedly inhibited dissociation of PHAS-I.eIF-4E, without decreasing MAP kinase activity. Rapamycin abolished the effects of insulin on increasing phosphorylation of ribosomal protein S6 and on activating p70S6K. The MAP kinase kinase inhibitor, PD 098059, markedly decreased MAP kinase activation by insulin, but it did not change PHAS-I phosphorylation or the association of PHAS-I with eIF-4E. In summary, insulin increases the expression of PHAS-I and promotes phosphorylation of multiple sites in the protein via multiple transduction pathways, one of which is rapamycin-sensitive and independent of MAP kinase. Rapamycin may inhibit translation initiation by increasing PHAS-I binding to eIF-4E.

Treatment of human hepatocellular carcinoma by fibroblast-mediated human interferon alpha gene therapy in combination with adoptive chemoimmunotherapy

The therapeutic effect of the fibroblast-mediated human interferon (IFN alpha) gene therapy in combination with interleukin-2 (IL-2) activated killer cells (AK)/doxorubicin (i.e., adoptive chemoimmunotherapy) on nude mice bearing the human hepatocellular carcinoma (HCC) was investigated. A fibroblast cell clone (NIH3T3-IFN alpha+) secreting 1024 U/ml human IFN alpha was obtained from 14 positive clones by BMGNeo-IFN alpha DNA transfection, G418-resistant selection, limiting dilution and assay of IFN alpha activity. After i.p. implantation of NIH3T3-IFN alpha+ encapsulated into collagen, serum human IFN alpha activity could be detected from 12 h to day 15 with a peak at 72 h. AK were prepared from human peripheral mononuclear cells costimulated in vitro by IL-2 and inactivated human SMMC 7721 HCC cells. When the NIH3T3-IFN alpha+ cells were i.p. implanted into the HCC-bearing nude mice, the grown of HCC was inhibited and the survival time of the mice was extended. The growth of HCC was inhibited more obviously when AK was i.v. injected and IL-2 was i.p. injected after the NIH3T3-IFN alpha+ cells had been implanted. The best therapeutic effect was achieved when NIH3T3-IFN alpha+ cells were used in combination with IL-2/AK/doxorubicin. All these results suggested that the fibroblast-mediated human IFN alpha gene therapy could be used to treat the human hepatocellular carcinoma effectively and that when used in combination with IL-2-based adoptive chemoimmunotherapy, the therapeutic effect would be better.

cAMP- and rapamycin-sensitive regulation of the association of eukaryotic initiation factor 4E and the translational regulator PHAS-I in aortic smooth muscle cells

Incubating rat aortic smooth muscle cells with either platelet-derived growth factor BB (PDGF) or insulin-like growth factor I (IGF-I) increased the phosphorylation of PHAS-I, an inhibitor of the mRNA cap binding protein, eukaryotic initiation factor (eIF) 4E. Phosphorylation of PHAS-I promoted dissociation of the PHAS-I-eIF-4E complex, an effect that could partly explain the stimulation of protein synthesis by the two growth factors. Increasing cAMP with forskolin decreased PHAS-I phosphorylation and markedly increased the amount of eIF-4E bound to PHAS-I, effects consistent with an action of cAMP to inhibit protein synthesis. Both PDGF and IGF-I activated p70S6K, but only PDGF increased mitogen-activated protein kinase activity. Forskolin decreased by 50% the effect of PDGF on increasing p70S6K, and forskolin abolished the effect of IGF-I on the kinase. The effects of PDGF and IGF-I on increasing PHAS-I phosphorylation, on dissociating the PHAS-I-eIF-4E complex, and on increasing p70S6K were abolished by rapamycin. The results indicate that IGF-I and PDGF increase PHAS-I phosphorylation in smooth muscle cells by the same rapamycin-sensitive pathway that leads to activation of p70S6K.

Multiple-hologram storage for thin layers of Methyl Orange dyes in polyvinyl alcohol matrices

We realized hologram storage within a 0.07-cm(2) light spot in thin layers of polyvinyl alcohol matrices doped with Methyl Orange dyes preirradiated by the 488.0-nm line of an Ar-ion laser with two orthogonal linearly polarized 632.8-nm light beams. By rotation of the sample, multiple-hologram storage was achieved. By controlling the writing time, we have recorded three-hologram and f ive-hologram images in the same light spot. The mechanism of the multiple-hologram storage in Methyl Orange-doped polyvinyl alcohol thin films is discussed.

[Experimental study on the treatment of human hepatocellular carcinoma by fibroblast-mediated human IFN-alpha gene therapy in combination with adoptive chemoimmunotherapy]

In the present study, we observed the therapeutic effect of the fibroblast-mediated human IFN alpha gene therapy in combination with IL-2/AK/DOX adoptive chemoimmunotherapy on human hepatocellular carcinoma-bearing nude mice. Activated killer cells (AK) were prepared from human peripheral mononuclear cells co-stimulated in vitro with IL-2 and inactivated human hepatocellular carcinoma SMMC 7721 cells. The results demonstrated that (1) When the NIH3T3-IFN-alpha+ cells were implanted i.p. to the tumor-bearing nude mice, the growth of tumor was inhibited and the survival time of the mice was prolonged; (2) The growth of tumor was significantly inhibited when AK was injected i.v. and IL-2 was injected i.p. after the NIH3T3-IFN-alpha+ cells had been implanted; (3) The best therapeutic results could be achieved when NIH3T3-IFN-alpha+ cells were used in combination with IL-2/AK/DOX. All these results suggeste that the fibroblast-mediated human IFN-alpha gene therapy could be used to treat human hepatocellular carcinoma but better results can be obtained when used in combination with IL-2-based immunotherapy.

Arresting amyloidosis in vivo using small-molecule anionic sulphonates or sulphates: implications for Alzheimer's disease

Amyloid is a term for extracellular protein fibril deposits that have characteristic tinctorial and structural properties. Heparan sulphate, or the heparan sulphate proteoglycan perlecan, has been identified in all amyloids and implicated in the earliest stages of inflammation-associated (AA) amyloid induction. Heparan sulphate interacts with the AA amyloid precursor and the beta-peptide of Alzheimer's amyloid, imparting characteristic secondary and tertiary amyloid structural features. These observations suggest that molecules that interfere with this interaction may prevent or arrest amyloidogenesis. We synthesized low-molecular-weight (135-1,000) anionic sulphonate or sulphate compounds. When administered orally, these compounds substantially reduced murine splenic AA amyloid progression. They also interfered with heparan sulphate-stimulated beta-peptide fibril aggregation in vitro.

Nonlinear changes in brain's response in the event of injury as detected by adaptive coherence estimation of evoked potentials

Injury-related changes in evoked potentials are studied with the aid of the coherence function, which effectively measures the degree of linear association between a pair of signals recorded during normal and abnormal states of the brain. The performance of an adaptive algorithm for estimating coherence function is studied, and the effects of additive noise on the estimated coherence function is discussed. Further, a linearity index is formulated and, through analysis and simulations, the index is shown to respond in a predictable manner to increasing nonlinearity while maintaining the robustness to the observation noise. Somatosensory evoked potentials are shown to be sensitive to injury resulting from acute cerebral hypoxia. We analyze the somatosensory evoked potentials recorded from anesthetized cats during inhalation of 8-9% oxygen gas mixtures and during recovery with 100% oxygen. Analyses of the experimental data show a very sharp drop in the magnitude coherence estimates during hypoxic injury and a corresponding rapid decline in the linearity index at the very early stages of the hypoxic injury. Thus, injury may lead to nonlinearities in the electrical response of the brain, and such measurements analyzed by the adaptive coherence estimation method may be used for diagnostic purposes.

PHAS-I as a link between mitogen-activated protein kinase and translation initiation

PHAS-I is a heat-stable protein (relative molecular mass approximately 12,400) found in many tissues. It is rapidly phosphorylated in rat adipocytes incubated with insulin or growth factors. Nonphosphorylated PHAS-I bound to initiation factor 4E (eIF-4E) and inhibited protein synthesis. Serine-64 in PHAS-I was rapidly phosphorylated by mitogen-activated (MAP) kinase, the major insulin-stimulated PHAS-I kinase in adipocyte extracts. Results obtained with antibodies, immobilized PHAS-I, and a messenger RNA cap affinity resin indicated that PHAS-I did not bind eIF-4E when serine-64 was phosphorylated. Thus, PHAS-I may be a key mediator of the stimulation of protein synthesis by the diverse group of agents and stimuli that activate MAP kinase.

Ras signaling in the activation of glucose transport by insulin

An approach involving microinjection and microanalysis has been developed to investigate signal-transduction pathways involved in the hormonal control of metabolism. We have applied this strategy to investigate the role of Ras signaling in the acute activation of glucose transport by insulin in cardiac myocytes. Glucose transport activity was assessed by measuring the initial rate of accumulation of 2-deoxyglucose 6-phosphate (dGlc6P) in individual cells after incubation in 2-deoxyglucose. Insulin increased accumulation of dGlc6P by 3- to 4-fold, consistent with its stimulatory effect on glucose transport. Accumulation of dGlc6P was increased severalfold by microinjecting the nonhydrolyzable GTP analogue, guanosine 5'-[gamma-thio]triphosphate, which activates members of the Ras superfamily of GTP-binding proteins. Injecting activated Ha-Ras protein also mimicked insulin by increasing dGlc6P; whereas, injecting a Ras protein lacking the COOH-terminal site of fatty acylation required for Ras function was without effect. Introducing the neutralizing Ras antibody Y13-259 into cells attenuated the effect of insulin. These findings implicate Ras in the acute regulation of metabolism by insulin.

Glucose transporters in single skeletal muscle fibers. Relationship to hexokinase and regulation by contractile activity

Glucose transport and phosphorylation are the first steps in the utilization of extracellular glucose by skeletal muscle. We have examined the relationships between proteins mediating these steps in single fibers of identified type dissected from rabbit skeletal muscle. The level of the glucose transporter isoform GLUT4, measured by immunoblotting, varied among fibers by a factor of 20 (slow oxidative > fast oxidative glycolytic > fast glycolytic). In fibers from the tibialis anterior muscle, GLUT4 was correlated (r2 = 0.75) with the activity of malate dehydrogenase, an enzyme representative of oxidative energy metabolism. In these fibers a strong correlation (r2 = 0.70) was also observed between GLUT4 and hexokinase activity. GLUT1 levels were barely detectable, regardless of fiber type. To investigate the possible role of muscle activity in controlling the expression of transporters, tibialis anterior muscles were activated by chronic electrical stimulation of the peroneal nerves. GLUT1 levels increased after 1 day of stimulation to a plateau that was severalfold higher than the level in non-stimulated cells. Hexokinase activity and the GLUT4 level changed in parallel: both were increased by approximately 2.5-fold after 1 day and by 14-fold after 21 days. Thus, while both GLUT1 and GLUT4 were regulated by muscle activity, only GLUT4 expression was coordinated with the expression of hexokinase.

Molecular cloning and tissue distribution of PHAS-I, an intracellular target for insulin and growth factors

Although the actions of insulin and a number of growth factors that signal via protein-tyrosine kinase receptors are believed to involve increased phosphorylation of key intracellular proteins, relatively few of the downstream phosphoproteins have been identified. In this report we describe a cDNA encoding one of the most prominent insulin-stimulated phosphoproteins in rat adipocytes. The cDNA encodes a protein, designated PHAS-I, which has 117 amino acids and a M(r) of 12,400. When translated in vitro and subjected to SDS/PAGE, PHAS-I migrates anomalously, having an apparent M(r) of 21,000. The predicted amino acid composition is interesting in that approximately 45% of the PHAS-I protein is accounted for by only four amino acids--serine, threonine, proline, and glycine. The PHAS-I gene is expressed in a variety of tissues, although the highest levels of mRNA are present in fat and skeletal muscle, two of the most insulin-responsive tissues. The nucleotide and deduced amino acid sequences of PHAS-I differ from any that have been reported, and homology screening provided no clues concerning the function of the protein. However, in view of its tissue distribution and the fact that the protein is phosphorylated in response to insulin, we speculate that PHAS-I is important in insulin action.

Glucose transport and phosphorylation in single cardiac myocytes: rate-limiting steps in glucose metabolism

Microanalytic methods were used to investigate the regulation of glucose metabolism by insulin in single myocytes isolated from adult rat ventricles. Cultured myocytes were incubated with or without insulin and, with either glucose or 2-deoxyglucose (2-DG), rinsed, and freeze-dried. Individual cells were weighed and levels of 2-DG-6-phosphate (2-DG-6-P) or glucose and glucose 6-phosphate (G-6-P) were determined after enzymatic amplification. In cells incubated with 2-DG, insulin increased the level of 2-DG-6-P by as much as 30-fold, indicative of dramatic activation of glucose transport. In cells incubated with glucose, insulin increased the levels of G-6-P by approximately threefold. Increasing extracellular glucose without insulin also increased G-6-P; however, intracellular glucose concentrations were not increased, indicating that glucose transport is rate limiting in nonstimulated myocytes. In contrast, intracellular glucose concentrations were increased by over an order of magnitude by insulin, reaching 60% of the extracellular glucose concentration. Measurements of glucose and G-6-P in the same insulin-treated cells revealed that accumulation of G-6-P reached a plateau when extracellular glucose was increased > 2 mM. At this point the estimated intracellular glucose concentration was 300 microM, or approximately 10 times the Michaelis constant of hexokinase for glucose. These results indicate that in the presence of insulin and physiological concentrations of glucose, hexokinase is saturated with glucose. Consequently, the rate-limiting step for insulin-stimulated glucose utilization is glucose phosphorylation rather than glucose transport.

Increasing cAMP attenuates activation of mitogen-activated protein kinase

Activation of the mitogen-activated protein kinase (MAP kinase) isoforms ERK1 and ERK2 was investigated in rat adipocytes. Kinase activities were measured by using myelin basic protein as substrate after the isoforms were resolved by Mono Q chromatography or by immunoprecipitation with specific antibodies. Insulin increased the activity of both isoforms by 3- to 4-fold. The beta-adrenergic agonist isoproterenol was without effect in the absence of insulin but markedly reduced the increases in ERK1 and ERK2 activities produced by the hormone. MAP kinase activation was also attenuated by forskolin and glucagon, which increase intracellular cAMP, and by dibutyryl-cAMP, 8-bromo-cAMP, and 8-(4-chlorophenylthio)-cAMP. Thus, increasing cAMP is associated with decreased activation of MAP kinase by insulin. Forskolin also inhibited activation of MAP kinase by several agents (epidermal growth factor, phorbol 12-myristate 13-acetate, and okadaic acid) that act independently of insulin receptors. Moreover, forskolin did not inhibit insulin-stimulated tyrosine phosphorylation of the insulin receptor substrate IRS-1. Therefore, the inhibitory effect on MAP kinase did not result from compromised functioning of the insulin receptor. The inhibitory effect was not confined to adipocytes, as forskolin and dibutyryl-cAMP inhibited the increase in MAP kinase activity by phorbol 12-myristate 13-acetate in wild-type CHO cells. In contrast, these agents did not inhibit MAP kinase activity in mutant CHO cells (line 10248) that express a cAMP-dependent protein kinase resistant to activation by cAMP. Our results suggest that activation of cAMP-dependent protein kinase represents a general counter-regulatory mechanism for opposing MAP kinase activation.

Biochemical analysis of a mutant Tetrahymena lacking outer dynein arms

Tetrahymena thermophila mutants homozygous for the oad mutation become nonmotile when grown at the restrictive temperature, and axonemes isolated from nonmotile mutants lack approximately 90% of their outer dynein arms. Electrophoretic analyses of axonemes isolated from nonmotile mutants (oad axonemes) indicate they contain significantly fewer of the 22 S dynein heavy chains that axonemes isolated from wild-type cells (wild-type axonemes) contain. The 22 S dynein heavy chains that remain in axonemes isolated from nonmotile, oad mutants are assembled into 22 S dynein particles that exhibit wild-type levels of ATPase activity. Two-dimensional gel electrophoresis of oad axonemes show that they are deficient in no proteins other than those proteins thought to be components of 22 S dynein. This report is the first formal proof that outer dynein arms in Tetrahymena cilia are composed of 22 S dynein.

The therapeutic and biological effects of total lymph node irradiation and autologous bone marrow infusion on malignant lymphoma patients

Forty patients with malignant lymphoma were treated by 60Co total lymphoid irradiation (TLI): 21 cases received 6 Gy and 19 received 8 Gy. Ten also received autologous bone marrow infusion (ABMI). Acute radiation damage with digestive tract reaction and hemopoietic and immunological depression was observed. Bone marrow was depressed. WBC and platelets decreased rapidly. Lymphocytes showed quantitative and qualitative changes even at the early stage. All these symptoms subsided within 40 days. TLI accompanied by irradiation of the tumor site could result in effective control. The 1-, 3-, and 5-year survival rates of malignant lymphoma patients were 30/40 (75%), 14/24 (58%) and 4/12 (33%), respectively, while in those with Hodgkin's disease alone, the 1- and 3-year survival rates were 10/13 (76%) and 5/7 (71.4%), respectively. ABMI hastened hemopoietic reconstitution, which recovered relatively quickly after TLI.

Reflection Zernike phase contrast microscope

A novel configuration for a reflection Zernike phase contrast microscope is given that has a height sensitivity of 0.5 A.