Cell-type specificity of interferon-gamma-mediated HLA class I gene transcription in human hematopoietic tumor cells

Major histocompatibility complex class I gene expression plays a central role in cellular immunity and tumor surveillance. A substantial proportion of spontaneous tumors are class I-deficient and numerous experiments have suggested that alterations in class I expression may alter oncogenicity and, as a result, have potential therapeutic impact. Interferons (IFNs) are able to upregulate class I expression by mechanisms that remain to be elucidated, but which appear to be IFN- and cell-type specific. We have characterized in detail the in vivo class I transcriptional response to IFN-gamma in two human hematopoietic tumor cell lines, the class I-deficient K562 cell line and the class I-positive Ramos cell line. In each, IFN-gamma induces a rapid increase in class I transcription, which is sustained in Ramos cells, but transient in K562 cells. In each, stimulation by IFN-gamma is dependent on ongoing protein synthesis, suggesting the requirement for production of a "primary response" protein. These data suggest that more than one type of IFN-gamma-induced signal is operative in the transcriptional response to IFN-gamma. Cycloheximide alone is also capable of inducing a rapid increase in class I transcription in both cell types, suggesting that constitutive attenuation of class I transcription may be a common phenomenon, and that IFN-gamma may act, in part, by interfering with such attenuation.

Identification of structural markers for vitamin B12 and other corrinoid derivatives in solution using FTIR spectroscopy

The identification of structural markers for B12/protein interactions is crucial to a complete understanding of vitamin B12 transport and metabolic reaction mechanisms of B12 coenzymes. Fourier transform infrared spectroscopy can provide direct measurements of changes in the side chains and corrin ring resulting from B12/protein interactions. Using FTIR spectroscopy in various solvent systems, we have identified structural markers for corrinoids in the physiological state. We assign the major band (denoted B), which occurs at ca. 1630 cm-1 in D2O and ca. 1675 cm-1 in ethanol, to the amide I C=O stretching mode of the propionamide side chains of the corrin ring. The lower frequency of band B in D2O versus ethanol is due to the greater hydrogen-bonding properties of D2O that stabilize the charged amide resonance form. Since the propionamides are known to be important in protein binding, band B is a suitable marker for monitoring the interaction of these side chains with proteins. We assign bands at ca. 1575 and 1545 cm-1 (denoted C and D) as breathing modes of the corrin ring on the basis of the bands' solvent independence and their sensitivity to changes in axial ligation. As the sigma-donating strength of the axial ligands increases, the frequencies of bands C and D decrease, possibly indicating a lengthening of the corrin conjugated system. Band A, the known cyanide stretching frequency at ca. 2130 cm-1, probes the cobalt-carbon distance in cyanocorrinoids. As the frequency of band A increases, the cobalt-carbon bond strength should decrease.

Lipid and protein density in the rat retina: a microradiographical study

Lipid and protein density in each retinal layer were determined microradiographically in retinal sections of 10 rats. Lipid in retinal sections was extracted with chloroform. The fraction of dry mass remaining after lipid extraction is mainly protein. The dry mass lost in chloroform processing was calculated to obtain the lipid density, which accounts for about 30% of the total dry mass density. The total dry mass density in each retinal layer is the sum of the lipid and protein density. Lipid should be regarded as an important X-ray absorber when determining the dry mass density in the rat retina with microradiography.

Nanosecond transient absorption spectroscopy of coenzyme B12. Quantum yields and spectral dynamics

Photolysis of adenosylcobalamin leads to homolytic cleavage, similar to many of the B12-dependent enzyme reactions. Therefore, we have used photolysis to study the structure and lability of the cobalt-carbon bond. The nanosecond quantum yield for adenosylcobalamin is 0.23 +/- 0.04, higher than reported previously. The acidified form of adenosylcobalamin, so called "base-off" B12, has a much lower quantum yield at 0.045 +/- 0.015, demonstrating an inverse correlation between cobalt-carbon bond strength and quantum yield. Investigation of the wavelength dependence of the quantum yield shows that there is a highly efficient transmission of energy from the corrin ring to the cobalt-carbon bond. A comparison of nanosecond transient and static spectra showed small spectral differences. Therefore, any spectral relaxation of a sterically distorted corrin ring may be detectable only at sub-nanosecond timescales. Spectral analysis also provides data on the kinetics of recombination. In the absence of enzyme, geminate rebinding must be substantial, since the rate of Co(II) and deoxyadenosyl radical recombination is near the diffusion controlled limit. Therefore, it is likely that the enzyme functions to pull the geminate partners apart, perhaps as suggested previously, through a conformational change. The importance of geminate recombination in the mechanism of homolytic cleavage is further supported by a comparison of our results with picosecond transient absorption studies.

Activity distribution of cytochrome oxidase in the rat retina. A quantitative histochemical study

Cytochrome oxidase (CYO) is a key enzyme in the respiratory chain. Therefore, CYO has an important role in the cell metabolism. In the present study CYO activity in the rat retina was identified by histochemical staining. The density of the staining, corresponding to the activity of the CYO, was evaluated quantitatively by densitometry. A high CYO activity was found in the retinal pigment epithelium, in the inner segment of the photoreceptors, in the outer plexiform layer and in the inner plexiform layer. In the outer segment of the photoreceptors, in the outer nuclear layer, and in the inner nuclear layer the CYO activity was relatively low. An analysis of variance demonstrated that the precision in an estimation of a mean depends on the number of animals and the number of retinal sections per animal.

Differential activation by atrial and brain natriuretic peptides of two different receptor guanylate cyclases

Alpha atrial natriuretic peptide (alpha-ANP) and brain natriuretic peptide are homologous polypeptide hormones involved in the regulation of fluid and electrolyte homeostasis. These two natriuretic peptides apparently share common receptors and stimulate the intracellular production of cyclic GMP as a second messenger. Molecular cloning has defined two types of natriuretic peptide receptors: the ANP-C receptor of relative molecular mass (Mr) 60-70,000 (60-70 K), which is not coupled to cGMP production and may function in the clearance of ANP and the ANP-A receptor of Mr 120-140 K, which is a membrane form of guanylate cyclase in which ligand binding to the extracellular domain activates the cytoplasmic domain of the enzyme. Here we report the cloning and expression of a second human natriuretic peptide-receptor guanylate cyclase, the ANP-B receptor. The ANP-B receptor is preferentially activated by porcine brain natriuretic peptide rather than human alpha-ANP, whereas the ANP-A receptor responds similarly to both natriuretic peptides. These observations may have important implications for our understanding of the central and peripheral control of cardiovascular homeostasis.

Fc gamma receptor recognition of IgG ligand by human monocytes and macrophages

We examined the binding characteristics of human monocytes and macrophages with the IgG ligands, human monomeric IgG and a small human IgG aggregate, trimeric IgG. Our purpose was to utilize fresh monocytes, in vitro cultured monocytes, and alveolar macrophages in direct and indirect binding experiments. Freshly isolated monocytes expressed only a single binding site for IgG monomer and IgG trimer. In contrast, in vitro cultured monocytes, gamma-interferon-treated monocytes, and freshly isolated alveolar macrophages expressed a single binding site for IgG monomer and, in addition, a high and low affinity binding site for IgG trimer. The high affinity binding site for IgG trimer (Kd approximately equal to 1 nM) appeared identical to the binding site for IgG monomer. The low affinity binding site for IgG trimer (Kd = 50 to 250 nM) appeared to be due to Fc gamma RII, because antibody to Fc gamma RII inhibited its expression. Since Fc gamma RII, in contrast to Fc gamma RI, does not bind monomeric IgG, the data suggest that this low affinity receptor for trimeric IgG, Fc gamma RII, can bind low molecular weight circulating immune complexes at concentrations 10- to 100-fold lower than Fc gamma RI. Thus, these studies suggest that at 37 degrees C, macrophage Fc gamma RII may play a functional role in the recognition of small molecular weight immune complexes.

A fusion protein required for vesicle-mediated transport in both mammalian cells and yeast

A protein sensitive to N-ethylmaleimide catalyses the fusion of transport vesicles with Golgi cisternae in a mammalian cell-free system. By cloning and sequencing its gene from Chinese hamster ovary cells and by use of in vitro assays, we show that this fusion protein is equivalent to the SEC18 gene product of the yeast Saccharomyces cerevisiae, known to be essential for vesicle-mediated transport from the endoplasmic reticulum to the Golgi apparatus. The mechanism of vesicular fusion is thus highly conserved, both between species and at different stages of transport.

Collateralization and GAD immunoreactivity of descending pallidal efferents

The first phase of this study involves injecting a different fluorescent retrograde axonal tracer into the subthalamic nucleus, the substantia nigra, and the mesopontine tegmentum. Multiple labeled cells are found within the caudal third of the globus pallidus. The entopeduncular nucleus and adjacent basal forebrain structures such as the substantia innominata, lateral hypothalamus, bed nucleus of the stria terminalis, and central nucleus of the amygdala all exhibit some dye containing cell, although multiple labeled cells are rare. The second phase of this study involves injecting a different fluorescent retrograde tracer into either the substantia nigra, or the mesopontine tegmentum, and subsequent processing of the tissue for glutamic acid decarboxylase (GAD) immunocytochemistry. Many dye and antibody double-labeled cells could be found within the entopeduncular nucleus and the caudal third of the globus pallidus. This is in contrast to the surrounding basal forebrain regions with brainstem efferents which were rarely GAD-positive. This study indicates that the collateral pattern and immunocytochemistry of globus pallidus neurons with descending efferents are distinct from other basal forebrain neurons having similar efferents. These results also extend previous findings and suggest that the neuron of the pallidal complex are heterogeneous with respect to their patterns of projections. In particular, the present findings question previous assumptions concerning the homology of pallidal segments between primate and rodent species.

Human atrial natriuretic peptide receptor defines a new paradigm for second messenger signal transduction

We isolated cDNAs encoding a 115 kd human atrial natriuretic peptide (alpha ANP) receptor (ANP-A receptor) that possesses guanylate cyclase activity, by low-stringency hybridization with sea urchin Arbacia punctulata membrane guanylate cyclase probes. The human ANP-A receptor has a 32 residue signal sequence followed by a 441 residue extracellular domain homologous to the 60 kd ANP-C receptor. A 21 residue transmembrane domain precedes a 568 residue cytoplasmic domain with homology to the protein kinase family and to a subunit of the soluble guanylate cyclase. COS-7 cells transfected with an ANP-A receptor expression vector displayed specific [125I]alpha ANP binding, and exhibited alpha ANP stimulated cGMP production. These data demonstrate a new paradigm of cellular signal transduction where extracellular ligand binding allosterically regulates cyclic nucleotide second-messenger production by a receptor cytoplasmic catalytic domain.

Modulation of Fc gamma receptors on the human macrophage cell line U-937

Macrophage receptors for the Fc portion of IgG play an important role in host defense, inflammation, and the pathophysiology of autoimmune disorders. We studied one important function of Fc gamma receptors--the ability to bind IgG ligand. Direct binding experiments analyzed by nonlinear regression were consistent with monomeric and trimeric IgG binding to a single class of receptors. Indirect binding experiments were also consistent with this interpretation and revealed that both IgG ligands completely inhibited the binding of the other. In addition, we used an anti-Fc gamma RII monoclonal antibody known to compete for the Fc gamma RII ligand binding site and known to inhibit IgG trimer binding to other cells. At concentrations of antibody which saturated all Fc gamma RII sites, no inhibition of IgG trimer binding to U-937 was observed. This was evident despite the observation that the numbers of Fc gamma RI and Fc gamma RII, determined by equilibrium binding of monomeric IgG and anti-Fc gamma RII antibody, respectively, were similar on U-937. Monoclonal antibodies were used to compare the expression and modulation of Fc gamma receptor proteins with their ability to bind monomeric and trimeric IgG ligands. Dexamethasone and gamma-interferon regulated U-937 Fc gamma RI protein expression and IgG ligand binding to a similar degree. In contrast, the expression of Fc gamma RII was not altered by dexamethasone. Interferon-gamma primarily stimulated Fc gamma RI, as determined both by reactivity with monoclonal antibody (227 +/- 26%) and by monomeric IgG ligand binding (350 +/- 151%). In addition, dexamethasone inhibited by 33% the gamma-interferon effect on Fc gamma RI protein and by 56% the effect on Fc gamma RI binding of monomeric IgG. Preincubation of U-937 with anti-Fc gamma RII antibody did not alter the effect of dexamethasone or gamma-interferon on IgG trimer binding. These data indicate that on U-937 cells Fc gamma RII does not function in the recognition of small molecular weight immune complexes and that Fc gamma RI is the Fc gamma receptor responsible for the binding of both monomeric and trimeric human IgG. Furthermore, Fc gamma RI is the major Fc gamma receptor on U-937 that is modulated by both gamma-interferon and glucocorticoids.

Molecular characterization of HIV-1 isolated from a serum collected in 1976: nucleotide sequence comparison to recent isolates and generation of hybrid HIV

Human immunodeficiency virus type 1 (Z321 designate, HIV-1Z321), the oldest known HIV, was isolated from a serum sample collected in Zaire in 1976 and was molecularly cloned. Restriction enzyme analysis of unintegrated viral DNA revealed the presence of conserved restriction enzyme cleavage sites in the long terminal repeat sequences. Nucleotide sequence analysis of the 3' end of the viral DNA revealed a pattern similar to other HIV-1 isolates described. However, some of the common restriction sites present in other isolates were absent in HIV-1Z321. The extent of differences between HIV-1Z321 and recent isolates from North America and Zaire was 17.86-18.36% on the nucleotide sequence level and 26.5-33.2% difference in the predicted amino acid sequence in the envelope gene. Differences were also noted in 3'-orf (nef: according to HIV gene nomenclature; see Ref. 42) gene and U3 region of the long terminal repeat sequences of HIV-1Z321 and other isolates. Nucleotide sequence of a HIV-1 isolate, 12 years apart from the present isolates, will provide an important time calibration point for the evolutionary divergence of HIV isolates. Hybrid HIV was also generated by transfecting HIV-1Z321 and HIV-1HTLV-III viral DNAs into cells.

An urban community-based cancer prevention screening and health education intervention in Chicago

Most types of cancer are disproportionately present in black populations. Among all ethnic and racial groups, black people have the highest incidence of all types of cancer combined, experiencing the highest mortality and the worst survival rate. A major intervention effort has begun in Chicago, targeting women living in 10 south side community areas whose populations are almost all black and among the poorest in the city. The purposes of the intervention are to develop and evaluate ways to reduce morbidity and mortality from breast and cervical cancer. Three outcome measures are being used, the proportion of women who receive Papanicolaou smears, breast examinations, and mammograms; the scores derived from a knowledge, attitudes, and practices survey; and the stage of diagnosed cancer. The results are being evaluated in three locations, the 10 target community areas, a Chicago Health Department clinic located in the community, and Fantus Clinic at Cook County Hospital. The intervention consists of reducing barriers to care at both public clinic sites and delivering education and information within the community. Public health outreach workers who are culturally sensitive to the population bring word of the program to places frequented by women, including local businesses (such as beauty shops, grocery stores, pharmacies, and currency exchanges), public housing developments (one being the largest in the country), and facilities belonging to city services programs. The intervention was developed to permit its ready adoption in similar environments should the evaluation results prove its usefulness.

Na+ pump in renal tubular cells is regulated by endogenous Na+-K+-ATPase inhibitor from hypothalamus

Bovine hypothalamus contains a high affinity, specific, reversible inhibitor of mammalian Na+-K+-ATPase. Kinetic analysis using isolated membrane fractions showed binding and dissociation rates of the hypothalamic factor (HF) to be (like ouabain) relatively long (off rate = 60 min). To determine whether the kinetics of inhibition in intact cells might be more consistent with regulation of physiological processes in vivo, binding and dissociation reactions of HF in intact renal epithelial cells (LLC-PK1) were studied using 86Rb+ uptake and [3H]ouabain binding. As with membranes, a 60-min incubation with HF inhibited Na+-K+-ATPase in LLC-PK1 cells. In contrast to membrane studies, no prolonged incubation with LLC-PK1 was needed to observe inhibition of Na+-K+-ATPase. HF caused a 33% inhibition of ouabain-sensitive 86Rb+ influx within 10 min. Incubation of cells with HF followed by washout showed rapid reversal of pump inhibition and a doubling of pump activity. The dose-response curve for HF inhibition of LLC-PK1 86Rb+ uptake showed a sigmoidal shape consistent with an allosteric binding reaction. Thus HF is a potent regulator of Na+-K+-ATPase activity in intact renal cells, with binding and dissociation reactions consistent with relevant physiological processes.

A single receptor binds both insulin-like growth factor II and mannose-6-phosphate

Amino acid sequences deduced from rat complementary DNA clones encoding the insulin-like growth factor II (IGF-II) receptor closely resemble those of the bovine cation-independent mannose-6-phosphate receptor (Man-6-P receptorCI), suggesting they are identical structures. It is also shown that IGF-II receptors are adsorbed by immobilized pentamannosyl-6-phosphate and are specifically eluted with Man-6-P. Furthermore, Man-6-P specifically increases by about two times the apparent affinity of the purified rat placental receptor for 125I-labeled IGF-II. These results indicate that the type II IGF receptor contains cooperative, high-affinity binding sites for both IGF-II and Man-6-P-containing proteins.

Primary structure and mRNA localization of protein F1, a growth-related protein kinase C substrate associated with synaptic plasticity

Protein F1 is a neuron-specific, synaptic-enriched, membrane-bound substrate of protein kinase C (PKC) whose phosphorylation is related to synaptic plasticity in the adult. The sequence of 26 N-terminal amino acids was determined from purified rat protein F1. A 78-mer synthetic oligonucleotide designed from the partial N-terminal sequence enabled identification of protein F1 cDNA clones in a rat brain library. F1 protein is a 226 amino acid protein encoded by a 1.5 kb brain-specific, developmentally-regulated mRNA. Transcripts for protein F1 can be detected at birth, and their level declines after maturation. A full-length cDNA clone was transcribed and translated in vitro. Translation products could be immunoprecipitated with anti-F1 antibodies. In situ hybridization analysis revealed protein F1 transcripts in hippocampal pyramidal cells, but not in granule cells. In cerebellum, granule cells contained protein F1 mRNA, while Purkinje cells did not. Co-localization of protein F1 with protein kinase C-II [PKC-II (beta)], rather than PKC-I (gamma) suggests that PKC-II may phosphorylate protein F1.

Negative and positive regulation of human leukocyte antigen class I gene transcription in K562 leukemia cells

The mechanism of transcriptional activation of human leukocyte antigen class I genes by gamma interferon and 5-azacytidine was studied in K562 human leukemia cells. Nuclear run-on transcription assays with various protein and RNA synthesis inhibitors yield evidence for both stimulation of a positive regulatory factor and inhibition of an mRNA that codes for a labile repressor. A novel mechanism is proposed to explain how 5-azacytidine can activate repressed genes without affecting DNA methylation.

Human proto-oncogene c-kit: a new cell surface receptor tyrosine kinase for an unidentified ligand

Structural features of v-kit, the oncogene of HZ4 feline sarcoma virus, suggested that this gene arose by transduction and truncation of cellular sequences. Complementary DNA cloning of the human proto-oncogene coding for a receptor tyrosine kinase confirmed this possibility: c-kit encodes a transmembrane glycoprotein that is structurally related to the receptor for macrophage growth factor (CSF-1) and the receptor for platelet-derived growth factor. The c-kit gene is widely expressed as a single, 5-kb transcript, and it is localized to human chromosome 4 and to mouse chromosome 5. A c-kit peptide antibody permitted the identification of a 145,000 dalton c-kit gene product that is inserted in the cellular plasma membrane and is capable of self-phosphorylation on tyrosine residues in both human glioblastoma cells and transfected mouse fibroblasts. Our results suggest that p145c-kit functions as a cell surface receptor for an as yet unidentified ligand. Furthermore, carboxy- and amino-terminal truncations that occurred during the viral transduction process are likely to have generated the transformation potential of v-kit.

Sequence analysis, cellular localization, and expression of a neuroretina adhesion and cell survival molecule

A cDNA for purpurin, a secreted 20,000 dalton neural retina cell adhesion and survival protein, has been sequenced and expressed in mammalian cells. Purpurin mRNA is found in both embryonic and adult retina, but not the brain, heart, or liver. The protein is highly concentrated in the neural retina between the pigmented epithelium and the outer segments of the photoreceptor cells; it is synthesized by photoreceptor cells. The predicted purpurin sequence contains 196 residues, has approximately 50% sequence homology with serum retinol binding protein, and is a member of the alpha-2 mu-globulin superfamily. Purpurin binds retinol and may play a major role in retinol transport across the interphotoreceptor cell matrix.

Cloning and expression of human apolipoprotein D cDNA

The amino acid sequence of human apolipoprotein D, a component of high density lipoprotein, has been obtained from the cloned cDNA sequence. The 169-amino acid protein has no marked similarity to other apolipoprotein sequences, but has a high degree of homology to plasma retinol-binding protein and other members of the alpha 2u-globulin protein superfamily. Apolipoprotein D mRNA has been detected in human liver, intestine, pancreas, kidney, placenta, adrenal, spleen, and fetal brain tissue. Tissue culture cells transfected with the cloned cDNA secrete material that reacts with anti-apoD antibodies.

Two interleukin 1 genes in the mouse: cloning and expression of the cDNA for murine interleukin 1 beta

A human interleukin 1 beta (IL 1 beta) cDNA probe was utilized to identify a homologous murine cDNA clone. The murine cDNA encodes a 269-residue protein which is 67% homologous to human IL 1 beta. The murine sequence was engineered for expression in mammalian cells and directs the synthesis of biologically active IL 1. This protein, termed murine IL 1 beta, is only 22% homologous with the previously described murine IL 1 sequence. Both IL 1 alpha and IL 1 beta are encoded by single genes, but IL 1 beta mRNA is about fivefold more abundant in a stimulated macrophage cell line.

Two interleukin 1 genes in the mouse: cloning and expression of the cDNA for murine interleukin 1 beta

A human interleukin 1 beta (IL 1 beta) cDNA probe was utilized to identify a homologous murine cDNA clone. The murine cDNA encodes a 269-residue protein which is 67% homologous to human IL 1 beta. The murine sequence was engineered for expression in mammalian cells and directs the synthesis of biologically active IL 1. This protein, termed murine IL 1 beta, is only 22% homologous with the previously described murine IL 1 sequence. Both IL 1 alpha and IL 1 beta are encoded by single genes, but IL 1 beta mRNA is about fivefold more abundant in a stimulated macrophage cell line.

Insulin-like growth factor I receptor primary structure: comparison with insulin receptor suggests structural determinants that define functional specificity

To identify structural characteristics of the closely related cell surface receptors for insulin and IGF-I that define their distinct physiological roles, we determined the complete primary structure of the human IGF-I receptor from cloned cDNA. The deduced sequence predicts a 1367 amino acid receptor precursor, including a 30-residue signal peptide, which is removed during translocation of the nascent polypeptide chain. The 1337 residue, unmodified proreceptor polypeptide has a predicted Mr of 151,869, which compares with the 180,000 Mr IGF-I receptor precursor. In analogy with the 152,784 Mr insulin receptor precursor, cleavage of the Arg-Lys-Arg-Arg sequence at position 707 of the IGF-I receptor precursor will generate alpha (80,423 Mr) and beta (70,866 Mr) subunits, which compare with approximately 135,000 Mr (alpha) and 90,000 Mr (beta) fully glycosylated subunits.

Stimulation of tyrosine-specific protein phosphorylation in the rat liver plasma membrane by oxygen radicals

Incorporation of 32P from [gamma-32P]ATP into endogenous proteins, added histone and the copolymers Glu 80 Tyr 20 by rat liver plasma membranes was markedly increased by several naphthoquinones, including menadione. This stimulation was most marked with Glu 80 Tyr 20, has an absolute requirement for either dithiothreitol or reduced glutathione, and was inhibited by superoxide dismutase, catalase, and desferrioxamine to varying degrees depending on the quinones used. Their effectiveness in stimulating the apparent tyrosine-specific protein phosphorylation correlated with the rates of DTT-dependent redox cycling measured by oxygen consumption. Increased protein phosphorylation was also seen with particulate fractions isolated from hepatocytes incubated with quinones. A free radical-mediated mechanism is suggested for the quinone stimulation of protein phosphorylation.

The effect of butyl 2-cyanoacrylate on the middle and inner ear of the chinchilla

Butyl 2-cyanoacrylate was placed on the oval and round window of the ear of the chinchilla and was also used as an adhesive for myringoplasty with autogenous muscle fascia. Butyl 2-cyanoacrylate was found to be difficult to manipulate and moderately toxic to the middle ear; there were occasional significant reactions in the inner ear.

Multiple, distinct forms of bovine and human protein kinase C suggest diversity in cellular signaling pathways

A new family of protein kinase C-related genes has been identified in bovine, human, and rat genomes. The alpha-, beta-, and gamma-type protein kinase sequences are highly homologous, include a kinase domain, and potential calcium-binding sites, and they contain interspersed variable regions. The corresponding genes are located on distinct human chromosomes; the possibility of even greater genetic complexity of this gene family is suggested by Northern and Southern hybridization analyses.

The complete primary structure of protein kinase C--the major phorbol ester receptor

Protein kinase C, the major phorbol ester receptor, was purified from bovine brain and through the use of oligonucleotide probes based on partial amino acid sequence, complementary DNA clones were derived from bovine brain complementary DNA libraries. Thus, the complete amino acid sequence of bovine protein kinase C was determined, revealing a domain structure. At the amino terminal is a cysteine-rich domain with an internal duplication; a putative calcium-binding domain follows, and there is at the carboxyl terminal a domain that shows substantial homology, but not identity, to sequences of other protein kinase.

Gamma interferon and 5-azacytidine cause transcriptional elevation of class I major histocompatibility complex gene expression in K562 leukemia cells in the absence of differentiation

We studied the effects of gamma interferon (IFN-gamma) on HLA class I gene expression, differentiation, and proliferative capacity of K562 human leukemia cells. In the uninduced state, K562 cells show little or no class I gene expression but actively express the erythroid-specific gamma-globin gene as well as genes associated with cell proliferation, including the transferrin receptor, c-myc, and alpha-actin genes At both the surface protein and mRNA levels, IFN-gamma induces class I and beta 2-microglobulin gene expression, but does not alter the expression of the gamma-globin, transferrin receptor, c-myc, or alpha-actin genes. A 10-fold maximal induction of both class I surface protein and mRNA occurs at 48 h and is reversible upon withdrawal of IFN-gamma from the culture medium. In vitro nuclear run-on transcription assays were performed to directly establish that IFN-gamma exerts an early effect at the level of transcription, with maximal transcription rates occurring within 4 h. The difference between the time course of transcription induction and that of mRNA accumulation suggests that the regulation of class I gene expression in this human leukemic cell line also involves posttranscriptional mechanisms. Measurements of cell proliferation rates and cell cycle distribution, as well as the reversibility of the effects of IFN-gamma, demonstrate that the selective induction of class I genes in these cells occurs in the absence of differentiation.

Identification of the pleiotropic sacQ gene of Bacillus subtilis

The sacQ gene of Bacillus subtilis, a pleiotropic gene affecting the expression of a number of secreted gene products, has been identified as a small 46-amino-acid polypeptide. The increased expression of this polypeptide in strains carrying the sacQ36 allele, or in strains carrying the sacQ gene on a high copy plasmid, appears to be responsible for the phenotype of higher levels of proteases seen in these strains. A deletion of the sacQ gene had no apparent phenotype, indicating that it is not an essential gene.

Structural alteration of viral homologue of receptor proto-oncogene fms at carboxyl terminus

A role for proto-oncogenes in the regulation and modulation of cell proliferation has been suggested by the findings that the B-chain of platelet-derived growth factor (PDGF) is encoded by the proto-oncogene sis and that the erb-B oncogene product is a truncated form of the epidermal growth factor (EGF) receptor. Furthermore, the product of the proto-oncogene fms (c-fms) may be related or identical to the receptor for macrophage colony-stimulating factor (CSF-1). v-fms is the transforming gene of the McDonough strain of feline sarcoma virus (SM-FeSV) and belongs to the family of src-related oncogenes which have tyrosine-specific kinase activity. Furthermore, nucleotide sequence analysis of the v-fms gene product revealed topological properties of a cell-surface receptor protein. To elucidate the features involved in the conversion of a normal cell-surface receptor gene into an oncogenic one, we have now determined the complete nucleotide sequence of a human c-fms complementary DNA. The 972-amino-acid c-fms protein has an extracellular domain, a membrane-spanning region, and a cytoplasmic tyrosine protein kinase domain. Comparison of the feline v-fms and human c-fms sequences reveals that the proteins share extensive homology but have different carboxyl termini.

The organization and nucleotide sequence of the Bacillus subtilis hisH, tyrA and aroE genes

The nucleotide sequence of approximately 3 kb of Bacillus subtilis DNA distal to the trp operon was determined. Three open reading frames were found and these were shown to encode the hisH, tyrA and aroE genes. Integrative plasmids were constructed to interrupt transcription through this region. These data suggest that these three genes can be transcribed from both the trp promoter preceding the trp operon and from a promoter within the trpA structural gene.

Tyrosine kinase receptor with extensive homology to EGF receptor shares chromosomal location with neu oncogene

A novel potential cell surface receptor of the tyrosine kinase gene family has been identified and characterized by molecular cloning. Its primary sequence is very similar to that of the human epidermal growth factor receptor and the v-erbB oncogene product; the chromosomal location of the gene for this protein is coincident with the neu oncogene, which suggests that the two genes may be identical.

Nucleotide sequence of the partition function of Escherichia coli plasmid ColE1

The DNA nucleotide sequence of a 382-bp Hpa II fragment containing cer (ColE1 resolution) function responsible for ColE1 plasmid stability in dividing Escherichia coli was determined. The partition (par) region of pSC101 and the cer region have similar biological functions, as they both maintain plasmid stability through plasmid monomerization. Both regions contain 40- to 70-bp hairpin-loop structures that resemble bidirectional transcription terminators and share sequence homology with each other. Deletion mapping of the cer fragment shows that sequences extending beyond both sides of the terminator-like structure are also involved in the plasmid partition process.

Sleep and purposive behavior: inverse deviations from randomness of neuronal firing patterns in the feline thalamus. A new form of homeostasis?

In behaving cats trained to press a bar for small aliquots of milk reward, single neuronal firing patterns were monitored from the nucleus reticularis (NR) thalami during bar bressing (BP), subsequent quiet wakefulness with EEG spindles (S- QW ), grooming behavior (GR) and slow-wave sleep (SWS). The temporal patterns in the neuronal spike trains were analyzed using a non-parametric method based on relative relations between sequential spike intervals. The deviations of pattern occurrences from the random model were quantified. During BP, specific patterns occurred much more often while others occurred much less often than predicted by the random model. Patterns that were dominant during BP, were selectively suppressed or virtually eliminated during S- QW , GR and SWS, despite the increased firing rate; and, vice versa, patterns that were suppressed below chance level during BP, became dominant during S- QW , GR and SWS. The magnitudes of these inversions of the statistical distribution of patterns were not random but graded and positively correlated, thus indicating that they were homeostatically controlled. Since the inversions were already evident shortly after the satiated ceased bar pressing, they may be related to the 'need' for sleep. On the basis of the known mechanisms of pattern generation and changes in receptors for putative transmitters, it was postulated that the inversions of pattern distribution are related to the recuperative function of SWS, i.e. resensitization of receptors that had been desensitized during the animal's stereotypic BP performance. The NR and other neuronal ensembles seem to constitute an oscillatory system with two modes of reciprocal connectivities : one is supporting wakefulness and emission of specific firing patterns, and the other is incompatible with wakefulness and instead is associated with inversion of statistical distribution of firing patterns and recuperative function of SWS.

Complete nucleotide sequence of the glutamate dehydrogenase gene from Escherichia coli K-12

A 2.3-kb PstI- ClaI chromosomal DNA segment, carrying the complete coding region of the glutamate dehydrogenase (GDH) structural gene from Escherichia coli K-12, has been sequenced. The complete amino acid sequence (447 residues) of the GDH monomer has been deduced, and comparisons are made with reported amino acid sequences of GDH from other organisms.

Albumin influences sulfobromophthalein transport by hepatocytes of each acinar zone

To determine whether profiles of decreasing concentration were generated among hepatocytes of the liver acinus during the transport of sulfobromophthalein sodium (BSP), rat livers were perfused with various concentrations of this dye (10 microM to 1 mM) in the presence and absence of albumin. After steady-state conditions for the biliary secretion of BSP had been attained, pieces of liver were rapidly frozen. Following the alkalinization of cryostat-cut sections, the relative concentration of BSP in hepatocytes of each zone and the effect of albumin on this localization were quantitated by microspectrophotometry. The results showed that BSP, perfused in the absence of albumin, was efficiently extracted by the liver (95% on a single pass), generating distinct profiles of decreasing cellular concentration from zone 1 to zone 3 at every concentration of BSP. However, the addition of albumin to the perfusate greatly reduced the extraction of BSP from the sinusoidal compartment and resulted in the abolition of the differences in BSP content between hepatocytes of zone 1 and zone 3. These results represent a direct demonstration that, as predicted by mathematical modeling, binding of BSP to albumin indeed results in a more homogeneous distribution of BSP within the liver acinus. A simple and direct microspectrophotometric method is therefore available to follow the changes in the relative concentration of BSP among the hepatocytes of the various acinar zones.

Visual attention and neuronal firing patterns in the feline pulvinar nucleus of thalamus

In behaving cats, temporal patterns of neuronal firing were studied during slow wave sleep (SWS), motionless quiet wakefulness (QW) coupled with specific direction of the animal's attention, and during bar pressing performance (BP) for milk reward. The analysis was based on relative relations between sequential spike intervals. The strength of the method is based on the fact that the probabilities of occurrence of patterns are determined by the history of a spike train. During SWS, the neuronal firing modes closely followed the theoretical model of independent distribution of intervals, whereas during QW and BP specific for each neuron departures from the model, i.e., patterning was observed. Most importantly, in seven chronically studied neurons idiosyncratic patterns were related to direction of the animal's attention, and, very likely, to the visual forms the animals gazed at, because the patterns disappeared in the dark and during SWS without major changes in the mean firing rate. The replications of patterns upon recurrence of a particular direction of attention was proven statistically. The constancy and idiosyncrasy of these patterns were apparent even though the comparable episodes occurred several hours apart, and the animals slept and/or ate in between, and the distance, i.e., the retinal size of visual forms varied from one episode to another. On the basis of correlative evidence, it was argued that, compared to more abstract modes of information processing, the identification and quantification of patterns based on relative relations between intervals require the least amount of storage of intermediate results. Hence, these patterns are likely to represent a simple and phylogenetically old principle of communication between neurons. It was postulated that the idiosyncrasy and invariance of patterns may play a role in constancy of feature extraction and Gestalt perception.

Different pattern of codon recognition by mammalian mitochondrial tRNAs

Analysis of an almost complete mammalian mitochondrial DNA sequence has identified 23 possible tRNA genes and we speculate here that these are sufficient to translate all the codons of the mitochondrial genetic code. This number is much smaller than the minimum of 31 required by the wobble hypothesis. For each of the eight genetic code boxes with four codons for one amino acid we find a single specific tRNA gene with T in the first (wobble) position of the anticodon. We suggest that these tRNAs with U in the wobble position can recognize all four codons in these genetic code boxes either by a "two out of three" base interaction or by U.N wobble.

Acute calcium nephrotoxicity. An electron microscopical and semiquantitative light microscopical study

Rats were infused for three hours with doses of calcium gluconate to elevate serum calcium level and were killed either immediately after infusion or after 24 hours. Necrosis of proximal tubular cells was observed when serum calcium level was 16.0 mg/dl or higher. Above 16.0 mg/dl, an additional 5% of renal tubular profiles contained damaged cells for each 1 mg/dl in serum calcium. No difference in extent of damage was found in rats killed immediately or after 24 hours. Initial changes were formation of granular dense bodies in mitochondria, cell swelling, rupture, and extensive mitochondrial calcification. Renal tubular basement membrane changes appeared to be initiated by protrusion of cytoplasmic buds, forming ovoid bodies, which became embedded in the basement membrane. These ovoid bodies then appeared to serve as a nidus for further extensive basement membrane calcification.