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L Jamieson

Publications and source records attributed to L Jamieson.

At least 19 recordsLinked to original sources
PubMed2001

NF-kappaB/RelA transactivation is required for atypical protein kinase C iota-mediated cell survival.

In chronic myelogenous leukemia (CML), the oncogene bcr-abl encodes a dysregulated tyrosine kinase that inhibits apoptosis. We showed previously that human erythroleukemia K562 cells are resistant to antineoplastic drug (taxol)-induced apoptosis through the atypical protein kinase C iota isozyme (PKC iota), a kinase downstream of Bcr-Abl. The mechanism(s) by which PKC iota mediates cell survival to taxol is unknown. Here we demonstrate that PKC iota requires the transcription factor nuclear factor-kappaB (NF-kappaB) to confer cell survival. At apoptosis-inducing concentrations, taxol weakly induces IkappaB(alpha) proteolysis and NF-kappaB translocation in K562 cells, but potently induces its transcriptional activity. Inhibition of NF-kappaB activity (by blocking IkappaB(alpha) degradation) significantly sensitizes cells to taxol-induced apoptosis. Likewise, K562 cells expressing antisense PKC iota mRNA or kinase dead PKC iota (PKC iota-KD) are sensitized to taxol; these cells are rescued from apoptosis by NF-kappaB overexpression. Expression of constitutively active PKC iota (PKC iota-CA) upregulates NF-kappaB transactivation and rescues cells from apoptosis in the absence of Bcr-Abl tyrosine kinase activity. Using a chimeric GAL4-RelA transactivator, we find that taxol potently activates GAL4-RelA-dependent transcription. This activation was further upregulated by expression of PKC iota-CA and inhibited by expression of PKC iota-KD. Our results indicate that RelA transactivation is an important downstream target of the PKC iota-mediated Bcr-Abl signaling pathway and is required for resistance to taxol-induced apoptosis.

Cell Survival↗
PubMed2001

Cloning of a novel phosphatidylinositol kinase-related kinase: characterization of the human SMG-1 RNA surveillance protein.

We have cloned and characterized a new member of the phosphatidylinositol kinase (PIK)-related kinase family. This gene, which we term human SMG-1 (hSMG-1), is orthologous to Caenorhabditis elegans SMG-1, a protein that functions in nonsense-mediated mRNA decay (NMD). cDNA sequencing revealed that hSMG-1 encodes a protein of 3031 amino acids containing a conserved kinase domain, a C-terminal domain unique to the PIK-related kinases and an FKBP12-rapamycin binding-like domain similar to that found in the PIK-related kinase mTOR. Immunopurified FLAG-tagged hSMG-1 exhibits protein kinase activity as measured by autophosphorylation and phosphorylation of the generic PIK-related kinase substrate PHAS-1. hSMG-1 kinase activity is inhibited by high nanomolar concentrations of wortmannin (IC(50) = 105 nm) but is not inhibited by a FKBP12-rapamycin complex. Mutation of conserved residues within the kinase domain of hSMG-1 abolishes both autophosphorylation and substrate phosphorylation, demonstrating that hSMG-1 exhibits intrinsic protein kinase activity. hSMG-1 phosphorylates purified hUpf1 protein, a phosphoprotein that plays a critical role in NMD, at sites that are also phosphorylated in whole cells. Based on these data, we conclude that hSMG-1 is the human orthologue to C. elegans SMG-1. Our data indicate that hSMG-1 may function in NMD by directly phosphorylating hUpf1 protein at physiologically relevant sites.

Amino Acid Sequence↗
PubMed2001

Characterization, cloning and sequence analysis of the inducible Ochrobactrum anthropi AmpC beta-lactamase.

Ochrobactrum anthropi is resistant to most cephalosporins and penicillins due, at least in part, to the inducible expression of a single beta-lactamase. The beta-lactamase gene has been cloned and sequenced. It encodes an AmpC-type class 1 serine active-site enzyme that hydrolyses mainly cephalosporins and is resistant to inhibition by clavulanic acid. Expression of the ampC gene is inducible via a typical AmpR regulator, which is encoded upstream of ampC. Inducible expression is retained following cloning of O. anthropi ampR-ampC into Escherichia coli, confirming that the signal for AmpR activation in O. anthropi is the same as that used in the Enterobacteriaceae. This is the first reported example of an AmpC beta-lactamase outside of the gamma-subdivision of the bacterial kingdom. Genomic searches of other non-gamma-subdivision bacteria revealed a homologous ampR-ampC cluster in the plant symbiont, Sinorhizobium meliloti.

Amino Acid Sequence↗
PubMed1999

Protein kinase Ciota activity is necessary for Bcr-Abl-mediated resistance to drug-induced apoptosis.

K562 chronic myelogenous leukemia cells are highly resistant to chemotherapeutic drugs, such as taxol, that induce cell death by apoptosis. This resistance is mediated by the chimeric tyrosine kinase oncogene Bcr-Abl. However, little is known about the mechanism by which Bcr-Abl protects K562 cells from apoptosis. We recently demonstrated that expression of PKCiota is necessary for the resistance of K562 cells to taxol-induced apoptosis (Murray, N. R., and Fields, A. P. (1997) J. Biol. Chem. 272, 27521-27524). We now demonstrate that treatment of K562 cells with taxol leads to sustained activation of PKCiota. In contrast, Bcr-Abl-negative HL60 myeloid leukemia cells, which are sensitive to taxol-induced apoptosis, do not exhibit sustained PKCiota activation in response to taxol. Treatment of K562 cells with tyrphostin AG957, a selective Bcr-Abl inhibitor, blocks taxol-induced PKCiota activation and sensitizes these cells to taxol-induced apoptosis, indicating that PKCiota is a relevant downstream target of Bcr-Abl-mediated resistance. Furthermore, expression of constitutively active PKCiota by adenovirus-mediated gene transfer rescues AG957-treated K562 cells from taxol-induced apoptosis. Taken together, these results demonstrate that both Bcr-Abl and PKCiota activity are necessary for apoptotic resistance in K562 cells. Furthermore, they identify PKCiota as a critical downstream target of Bcr-Abl that is sufficient to mediate the anti-apoptotic effects of Bcr-Abl.

3T3 Cells↗
PubMed1994

Cloning of an intracellular receptor for protein kinase C: a homolog of the beta subunit of G proteins.

Protein kinase C (PKC) translocates from the soluble to the cell particulate fraction on activation. Intracellular receptors that bind activated PKC in the particulate fraction have been implicated by a number of studies. Previous work identified 30- to 36-kDa proteins in the particulate fraction of heart and brain that bound activated PKC in a specific and saturable manner. These proteins were termed receptors for activated C-kinase, or RACKs. In the following study, we describe the cloning of a cDNA encoding a 36-kDa protein (RACK1) that fulfills the criteria for RACKs. (i) RACK1 bound PKC in the presence of PKC activators, but not in their absence. (ii) PKC binding to the recombinant RACK1 was not inhibited by a pseudosubstrate peptide or by a substrate peptide derived from the pseudosubstrate sequence, indicating that the binding did not reflect simply PKC association with its substrate. (iii) Binding of PKC to RACK1 was saturable and specific; two other protein kinases did not bind to RACK1. (iv) RACK1 contains two short sequences homologous to a PKC binding sequence previously identified in annexin I and in the brain PKC inhibitor KCIP. Peptides derived from these sequences inhibited PKC binding to RACK1. Finally, RACK1 is a homolog of the beta subunit of G proteins, which were recently implicated in membrane anchorage of the beta-adrenergic receptor kinase [Pitcher, J., Inglese, L., Higgins, J. B., Arriza, J. A., Casey, P. J., Kim, C., Benovic, J. L., Kwatra, M. M., Caron, M. G. & Lefkowitz, R. J. (1992) Science 257, 1264-1267]. Our in vitro data suggest a role for RACK1 in PKC-mediated signaling.

Amino Acid Sequence↗
PubMed1989

Characterized and predictable rabbit uveitis model for antiinflammatory drug screening.

A model has been developed for the screening of antiinflammatory ophthalmic drugs in rabbits. This simple and rapid method is reproducible and uses fewer animals than do some other methods. Rabbits are sensitized to bovine serum proteins, then challenged intravitreally to induce a uveitis. The basis of the inflammatory response is shown to be due primarily to an immunologic mechanism. At 24 hr postchallenge, animals are sorted into treatment groups of approximately equal "titer" as defined by the slit lamp examination iris score which measures the magnitude of the immunologic response. Topical ocular treatment (control or drug) is then initiated and continued for a total of four days. Iris inflammation is evaluated by daily slit lamp exams. Results indicate that this model has statistically narrower frequency distribution of iris ratings than another published method, and is faster than other equally accurate and precise methods that depend upon blood antibody titer to sort animals.

Administration, Topical↗
PubMed1985

The thermogenic role of adipose tissue in the dog.

Brown adipose tissue was clearly present in neonatal dogs. In the adult the tissue was superseded by a tissue with the gross characteristics of white adipose. However despite their appearance adult adipose tissue depots may contribute to non-shivering thermogenesis. Regional blood flow measurements using injected radioactive microspheres indicated large increases in blood flow to adipose depots during infusion of noradrenaline. Coupled with blood flow estimations, measurement of arteriovenous differences in dissolved oxygen across the bladder fat depot demonstrated a quantitative increase in oxygen extraction by the depot during noradrenaline infusion. Acute activation of non-shivering thermogenesis in the dog was not associated with increased mitochondrial GDP-binding in adipose tissue. However chronic treatment with a beta-stimulant (LY79730) which increased capacity for non-shivering thermogenesis was associated with increased mitochondrial GDP-binding and cytochrome oxidase activity in peri-renal adipose tissue.

2-Hydroxyphenethylamine↗
PubMed1984

Effect of noradrenaline on oxygen consumption and tissue blood flow in young pigs.

Metabolic rate and tissue blood flow were measured by indirect calorimetry and the radioactive microsphere technique, respectively, in anaesthetized pigs aged 10, 17, and 28 days during infusions of saline or noradrenaline. Noradrenaline produced a rise in oxygen consumption in all pigs but the magnitude of the response declined with age in Large White pigs (percent increase: 10 days old, 29.5 +/- 3.3; 17 days old, 15.3 +/- 3.2; 28 days old, 5.4 +/- 0.17) and was less in 10-day-old Minipigs (9.1 +/- 5.1). Regional blood flow per gram of tissue was similar for pigs of all ages and noradrenaline produced increases in flow to heart and skin, and small reductions in blood flow to skeletal muscle. Noradrenaline increased average blood flow to adipose tissue (four sites) by 21-fold in 10-day-old Large White pigs, but had less effect in 10-day-old Minipigs (9.5-fold) and in older Large White pigs (9-fold), where the effect on metabolic rate was diminished. It is calculated that adipose tissue could be responsible for the increase in metabolic rate during infusion of noradrenaline. Macroscopically there are no gross differences between various adipose tissue depots in the pig but those which showed the greatest response to noradrenaline correspond to areas where brown adipocytes have previously been identified by electron microscopy.

Adipose Tissue↗
PubMedDate not supplied

Alcohol versus natural drying for newborn cord care.

OBJECTIVE: To compare alcohol cleaning and natural drying of newborn umbilical cords. DESIGN: Prospective, randomized controlled trial. SETTING: Tertiary-level university teaching hospital and level II community hospital. PARTICIPANTS: Of 1,876 singleton full-term newborns enrolled, 1,811 completed the study. INTERVENTIONS: Newborns, from birth until separation of the cord, were randomized to either (a) umbilical cleansing with 70% isopropyl alcohol at each diaper change or (b) natural drying of the umbilical site without special treatment. MAIN OUTCOME MEASURES: Umbilical infection, cord separation time, maternal comfort, and cost. RESULTS: No newborn in either group developed a cord infection. Primary care providers obtained cultures for cord concerns in 32 newborns (1.8%), with colonization for normal flora, Staphylococcus aureus, and Group B streptococcus proportionately equal in alcohol and air dry groups. Cord separation time was statistically significantly different (alcohol group, 9.8 days; natural drying group, 8.16 days; t = 8.9, p = < .001). Mothers described similar comfort with cord care and relief with cord separation. Costs of alcohol drying while in the hospital were greater than those of natural drying. CONCLUSIONS: (a) Evidence does not support continued use of alcohol for newborn cord care; (b) health care providers should explain the normal process of cord separation, including appearance and possible odor; and (c) health care providers should continue to develop evidence to support or eliminate historic practices.

2-Propanol↗