Phosphor image analysis of human p53 protein isoforms

Phosphor imaging was evaluated for detection, quantitation and resolution of multiphosphorylated protein isoforms separated by two-dimensional gel electrophoresis. A nuclear phosphoprotein, p53, was isolated by immunoprecipitation after biosynthetic labeling with 35S, 32P or 33P in cultured human cells. Of the three radionuclides, 35S was the most sensitive in detection after a 1-week exposure, although shorter exposure times were effective. In dividing cells, 11 35S-labeled isoforms were found, of which 10 were phosphorylated by 33P and 32P. Exposure of phosphonuclides for one half-life showed that 33P radiolabeling produced better resolution among isoforms than 32P but was less sensitive in detection. Volume integration showed phosphorylated isoforms comprised from 1% to 25% of total isoform signal. The relative phosphorylation of each p53 isoform was estimated by normalizing 33P or 32P isoform volumes with the corresponding 35S volume and showed progressive phosphorylation of acidic isoforms. Additionally, phosphor imaging capably detected quantitative changes among individual isoforms after experimental modulation of the isoform pattern by serum deprivation. The described electrophoretic isolation and quantitation procedures should find general application in discerning active and inactive phosphoisoforms for eventual identification.

Altered protein synthesis in p53 null and hemizygous transgenic mouse embryonic fibroblasts

Embryonic fibroblasts derived from p53-deficient transgenic mice showed distinct phenotypic and biological changes in vitro. In this study, we investigated the possible impact of p53 on the synthesis of other cellular proteins by comparing the protein profiles of p53 null (-/-), hemizygous (+/-) and p53 positive homozygous (+/+) cells using high resolution two dimensional gel electrophoresis. A total of more than 850 proteins were detected in each cell line labeled with 35S-methionine by using computerized image analysis, and a number of proteins were detected with qualitative or quantitative changes in p53-/- cells and to a lesser extent in p53+/- cells. Specifically, seven proteins became undetectable, and no new proteins were detected in p53-/- cells. Neither newly expressed nor absent proteins were detected in p53+/- cell line. Quantitatively, a total of 97 and 59 proteins were detected with significant quantitative changes (3 fold or greater) in p53-/- and p53+/- cells, respectively. Generally, most protein changes fell into one of the following four patterns: 1) progressively decreased synthesis in cells from p53+/+ to p53+/- to p53-/- cells; 2) progressively increased synthesis in cells from p53+/+ to p53+/- to p53-/- cells; 3) decreased synthesis only in p53-/- cells; and 4) increased synthesis only in p53-/- cells. A 70 kD heat shock protein (Hsp 70) was identified and showed a greater than 1,000-fold increase in p53-/- cells compared to that in p53+/+ cells. Transferrin, tropomyosin, and proliferating cell nuclear antigen (PCNA) have also been identified and measured in this study. Synthesis of transferrin and tropomyosin was significantly increased or decreased, respectively in p53-/- cells, whereas expression of PCNA showed no significant change in p53-/- cells despite their much higher (3-4 times) proliferation rate than the other two cell lines (p53+/+ and p53+/- cells). We conclude that disruption of a single important gene, p53, results in a cascade of protein changes which are related to the loss of p53 mediated negative growth effects on cell cycle control.

Antinociceptive effect of intracerebroventricular injection of a tetrapeptide Asn-Ala-Gly-Ala in rats

The antinociceptive effect of intracerebroventricular injection (icv) of Asn-Ala-Gly-Ala (NAGA), a partial sequence of beta-lipotropin, was studied in rats. The potassium iontophoresis-induced tail flick was used to measure the pain threshold. The antinociceptive effect of NAGA, which was dose-dependent (icv, 0.03-0.24 mumol/rat) and long-lasting (90 min), was reversed by naloxone (icv, 0.26 mg.kg-1) and inhibited by anti-MEK serum (titre: 1:5000, 5 microliters) or anti-LEK serum (titre: 1:5000, 5 microliters). NAGA-induced antinociception was scarcely affected by anti-beta-EP serum (titre: 1:30,000, 5 microliters) or anti-Dyn A1-13 serum (titre: 1:30,000, 5 microliters). It was suggested that the antinociceptive effect of NAGA may be associated with the release of met-enkephalin and leu-enkephalin in rat brain.

Separation and sequencing of familiar and novel murine proteins using preparative two-dimensional gel electrophoresis

Strategies are needed for rapid protein isolation in order to identify disease-related proteins and facilitate the design of oligonucleotides for further molecular inquiry. In our laboratory, C3H10T1/2 murine fibroblasts have been found to express a variety of proteins in various subcellular fractions which are relevant to experimental transformation and carcinogenesis. Preparative two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) procedures were developed to identify major cytoplasmic proteins by electroblotting and microsequencing. Isoelectric focusing tube gels were enlarged to 6 mm ID to accommodate larger protein loads at 0.5 to 2 mg protein. Separated proteins were electrotransferred from 6 mm thick slab gels onto 0.22 mu polyvinylidene difluoride membranes. Nearly 100 prominent blotted proteins were stained with Coomassie Brilliant Blue between pI 4.5-7.0 and 18-106 kDa and, of these, 27 prominent and well-resolved proteins were selected for sequencing. Sequences of 14 to 24 amino acid residues in length were obtained from 11 proteins which were identified from computerized databases. Some of these identified proteins had structural or enzymatic functions while others had only recently been discovered, including a newly reported Hsp 70 class member and a novel calcium-binding protein, reticulocalbin. The new heat shock protein has a molecular mass of 75 kDa and has been designated as Grp75, PBP74, CSA or p66mot-1 in mice and humans with purported roles in transformation and antigen processing. Reticulocalbin is an endoplasmic reticular protein which contains six domains of the EF-hand motif associated with high-affinity calcium-binding proteins. It may be involved in protein transport and luminal protein processing. In addition, sequences of 5 to 11 residues in length were also obtained from six other unidentified proteins. Thus, we have found that preparative 2-D PAGE serves as a powerful one-step purification method for protein isolation and characterization from an important in vitro murine model for the study of carcinogenesis.

Phenotypic change and altered protein expression in X-ray and methylcholanthrene-transformed C3H10T1/2 fibroblasts

The morphology, growth properties and cellular protein patterns from parent and two transformed C3H10T1/2 cell lines were analyzed to associate the phenotypic and protein differences with cell transformation. Transformed 10T1/2 cells were obtained by colony isolation after exposure of parent 10T1/2 cells to methylcholanthrene (MCA-1 cell line) or X-ray irradiation (XR-III cell line). Compared to parent 10T1/2 and MCA-1 cells, XR-III cells were much smaller in size and exhibited the highest growth rate, greatest cell saturation density, increased plating efficiency and greater expression of proliferating cell nuclear antigen. MCA-1 cells showed intermediate characteristics between parent and XR-III cells. Among the three cell lines, only XR-III cells showed anchorage-independent growth in soft agar. When [35S]methionine-labeled whole cell lysate proteins were separated by two-dimensional polyacrylamide gel electrophoresis, computer comparison algorithms revealed a 97% similarity in protein profiles among almost 800 proteins detected from each cell line. However, comparison of proteins patterns of the transformed cell lines to that of parent 10T1/2 cells showed that 30 and 20 proteins were induced or repressed in XR-III cells and MCA-1 cells, respectively. Similarly, 81 and 24 proteins showed significant quantitative changes (threefold or greater) in XR-III and MCA-1 cells, respectively, as compared with parent 10T1/2 cell proteins. The anchorage-independent growth and increased proliferation properties of XR-III cells suggest a later stage of transformation compared to MCA-1 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Dual-polarization modes and self-heterodyne noise in a single-frequency 2.1-microm microchip Ho,Tm:YAG laser

We have observed, for the first time to our knowledge, residual stress-induced birefringent dual-polarization modes in a diode-pumped, single-frequency, microchip cw 2.0914-microm Ho,Tm:YAG laser. The two orthogonally polarized modes were separated in frequency by approximately 12 MHz and, when photodetected, produced a 12-MHz self-heterodyne beat signal. The self-heterodyne signal could be eliminated by an external lambda/4 plate and a polarizer to filter out one of the modes, but this required regulation of the pump laser power to better than 1%. These results have important implications for use of the microchip Ho,Tm:YAG laser in a heterodyne detection coherent lidar.

Evaluation of the critical value of driving fatigue based on the fuzzy sets theory

Applying the newly developed multistage evaluation method based on the fuzzy sets theory, we have evaluated the sense of driving fatigue of 8 male drivers who covered 400 km in 8 hr in the daytime, empirically revealing the distribution of the degree of driving fatigue. The critical values from "no" to "a bit" and "a bit" to "fatigued" are 1 and 5.5 hr, respectively. Finally, a tentative study of the psychophysical relations between driving time and driving fatigue has been made, leading to a curve of driving fatigue under the conditions of this experiment.

[Studies on film-covered soil setting seedling of Panax notoginseng (Burk.) F.H. Chengfu]

Film-covered soil setting seedling can markedly raise the yield of seedling and seedling establishment of Panax notoginseng, thus providing higher economic benefit. The increase of yield in trial plots was about 8.82%-24% higher than the control.

Application of high resolution two-dimensional polyacrylamide gel electrophoresis of polypeptides from cultured neonatal rat cardiomyocytes: regulation of protein synthesis by catecholamines

High resolution two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) was applied to cultured neonatal rat heart muscle cells, incubated for 72 h at 37 degrees C in serum-free medium, either in the absence or in the presence of 0.1 microM norepinephrine. After silver staining, about 340 and 550 protein spots could be seen in cardiomyocytes, cultured either in the absence or presence of norepinephrine. Of these spots, 141 could be further characterized according to isoelectric point and molecular weight, with 71 protein spots being present under both conditions. In cells cultivated in presence of norepinephrine, 58 new protein spots appeared, whereas 12 spots disappeared, and 22 spots increased (whereas 3 spots decreased) in intensity. In comparison with 2-D PAGE of rat cardiomyocytes, the protein pattern of the intact heart of neonatal rats is incongruent. 2-D PAGE of polypeptides of cultured neonatal rat cardiomyocytes may be a suitable tool to study the regulation of protein synthesis by various stimuli with relevance to cardiac growth adaptation, inotropy and heart failure.

Regulation of protein biosynthesis in neonatal rat cardiomyocytes by adrenoceptor-stimulation: investigations with high resolution two-dimensional polyacrylamide gel electrophoresis

The role of alpha- and beta-adrenoceptor-mediated regulation of protein patterns in cultured neonatal rat cardiomyocytes was studied with high resolution two-dimensional polyacrylamide gel electrophoresis. Spontaneously beating neonatal rat cardiomyocytes were cultured for 72 h at 37 degrees C in serum-free medium, supplemented with either the catecholamine norepinephrine (0.1 microM), or with norepinephrine (0.1 microM) plus the alpha 1-adrenoceptor blocker prazosin (1 microM), or with neither of these substances. In transmission light, 105 protein spots could be seen in the lysates from control cells, 244 spots were identified in lysates from norepinephrine-treated cells, and 114 protein species were counted in the case of lysates from cardiomyocytes which had been cultured in the presence of norepinephrine plus prazosin. This experimental approach allows a clear classification of alpha- and non-alpha (probably beta)-adrenoceptor-mediated catecholamine effects on protein synthesis in cardiomyocytes. In comparison with previous experiments (Chang et al., Electrophoresis, this issue, pp. 748-754), less protein species were identified in the untreated control cardiomyocytes, as well as in the norepinephrine treated cells. The only actual modification in the experimental setup in these two series was the addition of dimethyl sulfoxide--a substance known for its repressive effect on oncoprotein expression--to the culture medium, as solvent for prazosin.

[Alpha 2 megaloglobulin inhibits the activation of rabbit platelet by Chinese Agkistrodon acutus venom]

An in vitro study of alpha 2-mengaloglobulin (alpha 2MG) in the inhibition of the activation of washed rabbit platelet by Chinese Agkistrodon acutus venom (CAAV) was reported. Results showed that CAAV induced aggregation rate of washed rabbit platelet was positively related to the CAAV concentration, and the maximal aggregation rate was 43.8 +/- 9.9% at the concentration of 100 micrograms/ml. Meanwhile the release of serotonin (5-HT) and platelet factor 4(PF4) from the platelet reached maximum at the CAAV concentrations of 0.81 +/- 0.07 microgram/ml and 39.08 +/- 2.78%, respectively. Platelet aggregation and the release of 5-HT and PF4 induced by CAAV could be inhibited by the addition of 0.25% alpha 2 MG into the platelets both 1 minute before and 1 minute after the addition of CAAV. When alpha 2 MG was added to the platelets 1 minute prior to the addition of CAAV, the platelet aggregation and the ultrastructural changes which could be induced by CAAV were not observed, and the morphology of the rabbit platelets was the same as that of the normal counterparts.

Three-dimensional structure of Theiler murine encephalomyelitis virus (BeAn strain)

Depending on the strain, Theiler murine encephalomyelitis virus (TMEV) may cause acute encephalitis or chronic demyelinating disease, which is associated with viral persistence in mice. Persistent central nervous system infection and demyelination by the less-virulent TMEV has provided a useful animal model for the human demyelinating disease multiple sclerosis. The less-virulent BeAn strain of TMEV was crystallized and its atomic structure was determined by x-ray crystallography. The alpha-carbon coordinates of the closely related Mengo virus were used to calculate the initial phases to 3.5 A resolution and the interpretable electron density map was produced by 10 cycles of 30-fold noncrystallographic molecular replacement averaging. The structure revealed a high degree of overall structural similarity to Mengo virus as well as substantial differences in the surface loops. These structural changes might be correlated with TMEV host-specific recognition, pH-related stability, and neurovirulence.

Enhancement of motor nerve regeneration by nerve growth factor

The sciatic nerves of adult Wistar rats were severed bilaterally. Each nerve was sutured into a silicone tube used as a conduit, leaving a 5 mm gap in length between the nerve ends. Nerve growth factor in a saline solution vehicle was injected into the silicone chamber on the right side and normal saline solution (control) on the left. Six weeks after surgery, electrophysiological studies were performed. The motor nerve conduction velocities (MNCV) were significantly increased in the NGF-treated nerves. In one rat, the MNCV on the NGF-treated side was 66.6 m/s, in the range of normal nerves. There was no significant difference between the two sides in the amplitudes of evoked muscle action potentials. There are apparently no reports on the effect of NGF on motor neuron regeneration in vitro. In this study, NGF was found to enhance motor nerve regeneration.

Site-specific mutagenesis method which completely excludes wild-type DNA from the transformants

A highly efficient site-specific mutagenesis method has been devised to exclude wild-type DNA from incorporation into the transformed cells. Two complementary oligonucleotides, corresponding to a target sequence of a DNA molecule and containing an insertion mutation which created an endonuclease restriction site, were synthesized. By using the wild-type DNA molecule flanked by two restriction sites on each side of the target region as a template, the two oligonucleotide primers were extended, enriched, and isolated. The extended products, in turn, were used as templates in a polymerase chain reaction to obtain a mutagenized double-stranded DNA fragment which was conveniently cloned into plasmids by using the flanking restriction sites. Escherichia coli cells transformed by these plasmids were subject to large-scale analysis. One hundred percent of the transformants examined by colony hybridization, restriction enzyme analysis, and DNA sequencing were found to contain the mutant DNA sequence.

Hepatitis B virus DNA in sera of virus carriers positive exclusively for antibodies to the hepatitis B core antigen

The prevalence of serum HBV DNA in individuals positive for anti-HBc alone was determined by the polymerase chain reaction in two groups with endemic HBV infection from Canton (group A) and Hainan (group B), provinces of China. Twenty-one out of 294 individuals in group A (7.2%) and 193 out of 1995 in group B (9.7%) were positive for anti-HBc but negative for other markers of ongoing or past HBV infection (HBsAg and anti-HBs). HBV DNA was detected in 6/21 sera in group A (28.6%) and 68/193 in group B (35.2%) in their initial serum specimen. One of the six HBV-DNA-positive individuals in group A became negative after 6 months and four of the 58 positive in group B became negative at 4 years of follow-up. All of the individuals remained positive for anti-HBc and negative for anti-HBs, but one of them became positive for HBsAg on follow-up. None of the anti-HBc- and HBV-DNA-positive subjects had symptoms of liver diseases. They were, therefore, defined as chronic asymptomatic HBV carriers with undetectable HBsAg. This type of carrier should be added to the typical HBsAg-positive carrier, who constitutes about 10-15% of the general Chinese population, to give a more complete estimate of asymptomatic HBV carriers in China.

Expression of OKM5 antigen on keratinocytes in some dermatoses

Employing an avidin-biotin complex immunoperoxidase technique, it was found that there was OKM5 but no OKM1 antigen expression on the keratinocytes of the upper epidermis from all the studied specimens of seborrheic keratosis, verrucous nevus, Bowen's disease, BCC, SCC, MM, lichen planus, psoriasis vulgaris, condyloma acuminatum, and sporotrichosis as well as in two of eight cases of nevus pigmentosus. Our findings indicate that OKM5 antigen expression on epidermal keratinocytes is usually associated with dermal infiltration. It is assumed that human keratinocytes in cutaneous lesions, like the OKM1- OKM5+ monocyte/macrophage lineages, might play certain roles in immune responses and possibly function as antigen-presenting cells.

Carnivora: the primary structure of the hemoglobin from the silver fox (Vulpes vulpes var., Canidae)

The primary structure determination of the hemoglobin alpha- and beta-chains from the silver fox (Vulpes vulpes var., Canidae) is described. The separation of the chains could be achieved directly from the hemoglobin by RP-HPLC as well as by column chromatography of the globin using carboxymethyl-cellulose. Following tryptic digestion of the chains, the peptides were isolated by RP-HPLC. Amino-acid sequences were determined by Edman degradation in liquid and gas phase sequencers. The peptides could be aligned by homology with human and other Carnivora hemoglobins. Compared to human hemoglobin the alpha- and beta-chains of the silver fox exhibit 24 and 13 amino-acid exchanges, respectively. They differ by one alpha- and two beta-chain replacements from the domestic dog and the coyote. The substitutions affecting contact positions are discussed.

Carnivora: the primary structure of hemoglobin from the Masked Palm Civet (Paguma larvata, Viverridae)

The primary structure of the alpha- and beta-chains of hemoglobin from the Masked Palm Civet (Paguma larvata, Viverridae) is described. The chains were separated directly from hemoglobin by RP-HPLC. After tryptic digestion of the chains, the peptides were separated by RP-HPLC. Amino acid sequences were determined by Edman degradation in liquid and gas-phase sequencers. The alignment of the tryptic peptides was made by homology with human and other Carnivora hemoglobins. Paguma and human hemoglobin differ with respect to 23 amino-acid residues. Some of these amino-acid substitutions, which occur in both the alpha- and beta-chains, occur at contact sites between the subunits, and at the binding sites of heme and of organic phosphate, as well as involving residues responsible for the alkaline Bohr effect.

Secreted proteases. Regulation of their activity and their possible role in metastasis

Extracellular matrix metalloproteases are secreted by the resident cells of the tissue in a proenzyme form, and their extracellular activity is regulated at the level of gene expression, proenzyme activation, and interaction with inhibitors. To understand the molecular mechanisms that control the activity of ECM metalloproteases and their effect on the cellular phenotype, we have established cell lines in which the transcription of the protease genes is repressed. We also have undertaken a detailed study of the pathway of extracellular activation of interstitial procollagenase. Stable transfection of three human tumor cell lines--H-ras-transformed bronchial epithelial cells TBE-1, fibrosarcoma cells HT1080, and melanoma cells A2058--with the adenovirus E1A gene dramatically repressed the expression of the secreted proteases, type IV and interstitial collagenases, and urokinase-type plasminogen activator. Concomitantly, E1A-expressing cells showed reduced metastatic activity in vivo and reduced ability to traverse a reconstituted basement membrane in vitro. Monospecific anti-type IV collagenase antibody inhibited the invasive activity of parental tumor cell lines in the in vitro system, suggesting a possible causal relationship between the effect of E1A on the expression of secreted proteases and the reduced metastatic potential of the E1A-expressing transformants. We have also studied the mechanism of regulation of metalloprotease activity at the level of extracellular activation by investigating the cascade of proteolytic events that results in the activation of interstitial procollagenase. Cocultivation of the major cellular components of skin, dermal fibroblasts, and epidermal keratinocytes induces activation of interstitial procollagenase and prostromelysin in the presence of plasminogen. This activation occurs through a uPA-plasmin-dependent pathway in which plasmin catalyzes the first step in activation of both collagenase and stromelysin by amino-terminal processing. Activated stromelysin can in turn convert plasmin-activated collagenase into a fully active enzyme by removal of approximately 15 amino acid residues from the carboxyl end of the enzyme. This second step of activation results in a 5-8-fold further increase in specific activity of collagenase. This cascade of proteolytic events may constitute a major physiologic pathway of collagenase activation.

Microsomal metabolism of the Z and E isomers of N-nitroso-N-methyl-N-n-pentylamine

N-Nitrosomethyl-N-n-pentylamine was separated into its E and Z isomers by HPLC. When the metabolism was examined using microsomes isolated from uninduced Fischer 344 rats, it was found that, at a constant final concentration of 0.5 mM, the yield of formaldehyde produced increased as the proportion of the Z isomer rose. The yield of valeraldehyde, on the other hand, decreased with an increasing proportion of the Z isomer. Kinetic constants were determined for the metabolism of the two isomers. During the metabolism of the Z isomer, the Vmax was 2.2-fold higher for the formation of formaldehyde than that for the E. The Vmax for valeraldehyde was 2.0-fold lower during the metabolism of the Z isomer. The results indicate that the relative position of the nitroso group can have a profound effect on the metabolism of each side of this type of molecule.

Carnivora: primary structure of the hemoglobin from the spotted hyena (Crocuta crocuta, Hyenidae)

The primary structure of the alpha- and beta-chains of hemoglobin from spotted hyena (Crocuta crocuta, Hyenidae) is presented. The structure-function relationship is discussed. The separation of the chains directly from hemoglobin was performed by RP-HPLC. After tryptic digestion of the chains, the peptides were isolated by RP-HPLC. Amino-acid sequences were determined by Edman degradation in liquid- and gas-phase sequencers. The alignment of the tryptic peptides was made by homology with human and other Carnivora hemoglobins. The hemoglobin from spotted hyena (Crocuta crocuta) exhibits in its alpha- and beta-chains 22 and 20 exchanges, respectively, compared to human hemoglobin. In the alpha-chains, two alpha 1 beta 1-contacts are exchanged. In the beta-chains five exchanges involve one alpha 1 beta 1-contact, one alpha 1 beta 2-contact, one heme contact, and two 2,3-DPG-binding sites.