ABSTRACT
AIM: To translate, adapt and evaluate psychometric properties of the complete (15 items) and reduced (three items) versions of the Care Transitions Measure into Brazilian Portuguese. INTRODUCTION: The Care Transitions Measure assesses the quality of care transitions, from the perspective of patients. As accomplishing effective transitions is a challenge to healthcare systems, the instrument provides an opportunity to assess care transitions and improve quality initiatives. METHODS: A three-phased design was used for cross-cultural adaptation, pre-testing and evaluation of psychometric properties of the measurement in a Brazilian hospital. After forward translation, back translation and expert committee review, patients evaluated the instrument in a pre-test. Psychometric testing included face and content validity, reliability, stability and factorial analysis. RESULTS: Cross-cultural adaptation was completed successfully with a high clarity rate. Internal consistency was good in the 15-item version and was moderate in the three-item version. Test-retest reliability showed good stability of the two versions over time. The three-item version had satisfactory criterion validity. Four factors were extracted for the 15-item measure. LIMITATIONS: Samples were restricted to a group of patients from one hospital in southern Brazil. Future studies should test the measurement's construct and predictive validity. CONCLUSIONS: The translated version of the Care Transitions Measure has good face and content validity, reliability and stability. It has shown to be a valid measurement for evaluating the quality of care transitions in Brazil. IMPLICATIONS FOR NURSING AND HEALTH POLICY: Results are beneficial for nurses, managers and policy makers for evaluating care transitions and support the need for changes in policies and practices.
Subject(s)
Patient Transfer/standards , Quality of Health Care/standards , Surveys and Questionnaires/standards , Brazil , Humans , Psychometrics , Reproducibility of Results , TranslationsABSTRACT
Smooth muscle cells are exposed to growth factors and cytokines that contribute to pathological states including airway hyperresponsiveness, atherosclerosis, angiogenesis, smooth muscle hypertrophy, and hyperplasia. A common feature of several of these conditions is migration of smooth muscle beyond the initial boundary of the organ. Signal transduction pathways activated by extracellular signals that instigate migration are mostly undefined in smooth muscles. We measured migration of cultured tracheal myocytes in response to platelet-derived growth factor, interleukin-1beta, and transforming growth factor-beta. Cellular migration was blocked by SB203580, an inhibitor of p38(MAPK). Time course experiments demonstrated increased phosphorylation of p38(MAPK). Activation of p38(MAPK) resulted in the phosphorylation of HSP27 (heat shock protein 27), which may modulate F-actin polymerization. Inhibition of p38(MAPK) activity inhibited phosphorylation of HSP27. Adenovirus-mediated expression of activated mutant MAPK kinase 6b(E), an upstream activator for p38(MAPK), increased cell migration, whereas overexpression of p38alpha MAPK dominant negative mutant and an HSP27 phosphorylation mutant blocked cell migration completely. The results indicate that activation of the p38(MAPK) pathway by growth factors and proinflammatory cytokines regulates smooth muscle cell migration and may contribute to pathological states involving smooth muscle dysfunction.
Subject(s)
Calcium-Calmodulin-Dependent Protein Kinases/physiology , Cell Movement , Heat-Shock Proteins/physiology , Mitogen-Activated Protein Kinases , Muscle, Smooth/cytology , Adenoviridae/genetics , Animals , Dogs , Female , Interleukin-1/pharmacology , Male , Phosphorylation , Platelet-Derived Growth Factor/pharmacology , Signal Transduction , Transforming Growth Factor beta/pharmacology , p38 Mitogen-Activated Protein KinasesABSTRACT
Recent reports have demonstrated that the heat shock proteins (hsp) and in particular the hsp70 confer protection against cardiac ischemic damage. More recently, we have shown that increased expression of another heat shock protein, the hsp27, through an adenovirus vector system protects adult cardiomyocytes against ischemic injury. This small heat shock protein undergoes phosphorylation when the cell is under stress. This has led many to speculate that phosphorylation of hsp27 is required for the protective role this protein plays in the cell. In order to investigate this possibility, we have mutated the serines that are the sites of phosphorylation on the hsp27, to glycines or alanines. These nonphosphorylatable mutants of hsp27 were cloned into adenoviral vectors and used to infect adult rat cardiomyocytes to assess their ability in protecting against ischemic injury. In addition, we used a specific inhibitor of p38 MAP kinase that is a key member of the kinase pathway responsible for phosphorylating the hsp27. Our present results show that the nonphosphorylated hsp27 forms larger oligomeric complexes than the phosphorylated hsp27. Interestingly, phosphorylation of hsp27 seems not to play a role in its ability to protect adult rat cardiomyocytes against ischemic damage.
Subject(s)
Heat-Shock Proteins/physiology , Mitogen-Activated Protein Kinases , Myocardial Ischemia/prevention & control , Myocardium/metabolism , Animals , Calcium-Calmodulin-Dependent Protein Kinases/metabolism , Cells, Cultured , Heat-Shock Proteins/genetics , Heat-Shock Proteins/metabolism , Humans , Myocardium/cytology , Phosphorylation , Rats , Rats, Sprague-Dawley , p38 Mitogen-Activated Protein KinasesABSTRACT
Heat shock protein 70 (Hsp70) is thought to play a critical role in the thermotolerance of mammalian cells, presumably due to its chaperone activity. We examined the chaperone activity and cellular heat resistance of a clonal cell line in which overexpression of Hsp70 was transiently induced by means of the tetracycline-regulated gene expression system. This single-cell-line approach circumvents problems associated with clonal variation and indirect effects resulting from constitutive overexpression of Hsp70. The in vivo chaperone function of Hsp70 was quantitatively investigated by using firefly luciferase as a reporter protein. Chaperone activity was found to strictly correlate to the level of Hsp70 expression. In addition, we observed an Hsp70 concentration dependent increase in the cellular heat resistance. In order to study the contribution of the Hsp70 chaperone activity, heat resistance of cells that expressed tetracycline-regulated Hsp70 was compared to thermotolerant cells expressing the same level of Hsp70 plus all of the other heat shock proteins. Overexpression of Hsp70 alone was sufficient to induce a similar recovery of cytoplasmic luciferase activity, as does expression of all Hsps in thermotolerant cells. However, when the luciferase reporter protein was directed to the nucleus, expression of Hsp70 alone was not sufficient to yield the level of recovery observed in thermotolerant cells. In addition, cells expressing the same level of Hsp70 found in heat-induced thermotolerant cells containing additional Hsps showed increased resistance to thermal killing but were more sensitive than thermotolerant cells. These results suggest that the inducible form of Hsp70 contributes to the stress-tolerant state by increasing the chaperone activity in the cytoplasm. However, its expression alone is apparently insufficient for protection of other subcellular compartments to yield clonal heat resistance to the level observed in thermotolerant cells.
Subject(s)
HSP70 Heat-Shock Proteins/metabolism , Heat-Shock Response/physiology , Animals , Cell Line , Cell Nucleus/metabolism , Cell Survival , Cricetinae , Cytoplasm/metabolism , Gene Expression Regulation/drug effects , HSP70 Heat-Shock Proteins/genetics , Heating , Humans , Luciferases/metabolism , Temperature , Tetracycline/pharmacologyABSTRACT
This article provides an overview of the most commonly used instruments for excisional surgery. It has also discussed some of the specialty instruments that may be of value. It may serve as a starting point for the outfitting of a dermatologic surgery practice. However, it is no substitute for seeing, touching, and handling the instruments. At many of the larger specialty meetings, the instrument vendors will be displaying their wares. These displays offer an excellent opportunity to evaluate the many instruments. All of these fancy shiny instruments are merely tools to be used as an extension of the surgeon's hand and brain. They should work for the surgeon in a manner that is comfortable and efficient. Only the surgeon can decide what works best.
Subject(s)
Dermatology/instrumentation , Skin Diseases/surgery , Surgical Instruments/standards , Equipment Design , Equipment Safety , Humans , Operating Rooms , Surgical Procedures, Operative/methodsABSTRACT
The 27-kDa heat shock protein (HSP27) is expressed in a variety of tissues in the absence of stress and is thought to regulate actin filament dynamics, possibly by a phosphorylation/dephosphorylation mechanism. HSP27 has also been suggested to be involved in contraction of intestinal smooth muscle. We have investigated phosphorylation of HSP27 in airway smooth muscle in response to the muscarinic agonist carbachol. Carbachol increased 32P incorporation into canine tracheal HSP27 and induced a shift in the distribution of charge isoforms on two-dimensional gels to more acidic, phosphorylated forms. The canine HSP27 amino acid sequence includes three serine residues corresponding to sites in human HSP27 known to be phosphorylated by mitogen-activated protein kinase-activated protein (MAPKAP) kinase-2. To determine whether muscarinic receptors are coupled to a "stress response" pathway in smooth muscle culminating in phosphorylation of HSP27, we assayed MAPKAP kinase-2 activity and tyrosine phosphorylation of p38 mitogen-activated protein (MAP) kinase, the enzyme thought to activate MAPKAP kinase-2. Recombinant canine HSP27 expressed in Escherichia coli was a substrate for MAPKAP kinase-2 in vitro as well as a substrate for endogenous smooth muscle HSP27 kinase, which was activated by carbachol. Carbachol also increased tyrosine phosphorylation of p38 MAP kinase. SB-203580, an inhibitor of p38 MAP kinases, reduced activation of endogenous HSP27 kinase activity and blocked the shift in HSP27 charge isoforms to acidic forms. We suggest that HSP27 in airway smooth muscle, in addition to being a stress response protein, is phosphorylated by a receptor-initiated signaling cascade involving muscarinic receptors, tyrosine phosphorylation of p38 MAP kinase, and activation of MAPKAP kinase-2.
Subject(s)
Calcium-Calmodulin-Dependent Protein Kinases/metabolism , Colon/metabolism , Heat-Shock Proteins/metabolism , Mitogen-Activated Protein Kinases , Muscle, Smooth/metabolism , Protein Serine-Threonine Kinases/metabolism , Amino Acid Sequence , Animals , Carbachol/pharmacology , Cricetinae , Dogs , Enzyme Activation , Female , Gene Library , Heat-Shock Proteins/biosynthesis , Heat-Shock Proteins/chemistry , Humans , Imidazoles/pharmacology , Intracellular Signaling Peptides and Proteins , Kinetics , Male , Mice , Molecular Sequence Data , Phosphorylation , Phosphotyrosine , Pyridines/pharmacology , Rats , Recombinant Proteins/biosynthesis , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Sequence Alignment , Sequence Homology, Amino Acid , p38 Mitogen-Activated Protein KinasesABSTRACT
The heat shock response of a fish which inhabits a highly stressful environment (Poeciliopsis lucida, a minnow from river systems of the Sonoran desert in northwestern Mexico) was investigated. Cells derived from this fish exhibited a typical heat shock response when exposed to elevated temperature, synthesizing high levels of 90 kDa, 70 kDa, and 30 kDa heat shock proteins (Hsp90, Hsp70, and Hsp30), as well as lower amounts of other heat shock proteins. Additional small heat shock proteins (sHSPs), including Hsp27, were induced after a prolonged heat shock at a time when synthesis of Hsp70 and Hsp30 was decreasing. Characterization of cDNA clones for hsp27 and hsp30 revealed that both are members of the alpha-crystallin/sHSP superfamily but belong to separate lineages within this gene family. The multiple isoforms of P. lucida Hsp30 appear to be members of a multigene family and are most closely related to salmon and Xenopus Hsp30s. In contrast, Hsp27 is highly similar to mammalian and avian sHSPs; it was synthesized as three isoforms which represented differentially phosphorylated forms of a single polypeptide. In Poeciliopsis, the various sHSPs may each perform a subset of the roles attributed to mammalian sHSPs. The conservation of phosphorylation sites in Hsp27 may indicate an involvement in signal transduction to the actin cytoskeleton. The hsp30 genes appear to have diverged more rapidly than the corresponding hsp27 genes; the various members of the Hsp30 family may function as molecular chaperones and, in this role, may be less evolutionarily constrained. Finally, the presence of these two classes of sHSP in a single taxon indicates that these two lineages arose by gene duplication early in the evolution of vertebrates and raises questions about the fate of homologs of Hsp30 in mammals and of Hsp27 in Xenopus.
Subject(s)
Cyprinidae/genetics , Evolution, Molecular , Heat-Shock Proteins/chemistry , Heat-Shock Proteins/genetics , Membrane Proteins/chemistry , Phylogeny , Xenopus/genetics , Amino Acid Sequence , Animals , Base Sequence , Carcinoma, Hepatocellular/veterinary , Cell Line , Cloning, Molecular , Consensus Sequence , DNA, Complementary , Fish Diseases , HSP30 Heat-Shock Proteins , Humans , Liver Neoplasms/veterinary , Membrane Proteins/genetics , Molecular Sequence Data , Molecular Weight , Salmon , Sequence Alignment , Sequence Homology, Amino Acid , Xenopus ProteinsABSTRACT
The mammalian small stress protein hsp27 is an oligomeric phosphoprotein which interferes with the cell death induced by several stimuli. In that sense, we and others have recently shown that human hsp27 expression induced cellular protection against tumor necrosis factor (TNFalpha), a protection which depends on the ability of hsp27 to decrease the level of reactive oxygen species and increase that of glutathione. Here, we have analyzed unphosphorylatable mutants of human hsp27 in which serines 15, 78, and 82 were replaced by alanines, glycines, or aspartic acids. Depending on the amino acid which was used to substitute the serine sites, a different pattern of hsp27 structural organization was observed. Alanine substitution generated large hsp27 aggregates while glycine and aspartic acid did the reverse. Hence, these phosphorylatable serine residues can be considered as key elements affecting hsp27 structural organization. Only the large aggregates of hsp27 were able to modulate reactive oxygen species and glutathione and generated cellular protection against TNFalpha. Moreover, using drugs that modulate the intracellular level of glutathione, we show that an increase in glutathione by itself was sufficient to generate large hsp27 structures while the reverse was observed in the case of glutathione deprivation.
Subject(s)
Cell Survival/drug effects , Genes, ras , Glutathione/metabolism , Heat-Shock Proteins/metabolism , Reactive Oxygen Species/metabolism , Tumor Necrosis Factor-alpha/toxicity , 3T3 Cells , Amino Acid Substitution , Animals , Cell Line, Transformed , Dactinomycin/pharmacology , Heat-Shock Proteins/biosynthesis , Heat-Shock Proteins/isolation & purification , Humans , Mice , Mutagenesis, Site-Directed , Phosphorylation , Recombinant Proteins/biosynthesis , Recombinant Proteins/isolation & purification , Recombinant Proteins/metabolism , TransfectionABSTRACT
The small human heat shock protein hsp27 has been shown to play important roles in diverse cellular processes such as actin polymerization, thermotolerance, growth, and chemotherapeutic drug resistance. Two breast cancer cell lines MCF-7 and MDA-MB-231 were used as a model to study the molecular mechanisms important for basal hsp27 promoter transcriptional activity. A genomic clone containing 1.1 kb of the hsp27 promoter was sequenced and the regulatory elements were characterized. The first 200 bp within this 5'-flanking region holds the majority of the transcriptional activity, according to transient transfection assays using a series of hsp27 promoter deletion fragments in luciferase reporter vectors. The basal activity of this fragment is largely confined to a G/C-rich region containing overlapping SP1 and AP2 transcription factor binding sites.
Subject(s)
Heat-Shock Proteins/genetics , Promoter Regions, Genetic , Base Sequence , Binding Sites , DNA Primers/chemistry , DNA-Binding Proteins/metabolism , Gene Expression Regulation, Neoplastic , Humans , Molecular Sequence Data , Sequence Deletion , Sp1 Transcription Factor/metabolism , Transcription Factor AP-2 , Transcription Factors/metabolism , Transcription, Genetic , Tumor Cells, CulturedABSTRACT
The nucleotide (nt) sequence encoding a 27-kDa heat-shock protein (HSP27) was determined from cDNAs cloned from a canine smooth muscle library. The primary structure deduced from the nt sequence reveals a 209-amino-acid protein having 86-89% identity with human, mouse, rat and hamster small HSP. Similar to human HSP27, the canine protein contains three Ser residues that are potential MAPKAP kinase II substrates.
Subject(s)
DNA, Complementary/genetics , Heat-Shock Proteins/genetics , Amino Acid Sequence , Animals , Base Sequence , Cloning, Molecular , Cricetinae , Dogs , Heat-Shock Proteins/chemistry , Humans , Intracellular Signaling Peptides and Proteins , Mice , Molecular Sequence Data , Protein Serine-Threonine Kinases/metabolism , Rats , Sequence Homology, Amino Acid , Serine/chemistry , Species Specificity , Substrate SpecificityABSTRACT
Bovine arterial endothelial cells were stably transfected with the human wild-type (wt) HSP27 or a mutant gene (mu) encoding a nonphosphorylatable form of the protein. At early passage both cultural and cellular morphology were similar, although the vacuole content in wtHSP27 was much higher than muHSP27 cells. As the cultures aged, wtHSP27 cells became large, polymorphic, highly vacuolated, and reached senescence before muHSP27 transfected cultures, which remained small and polygonal with few detectable vacuoles. Vector control cells showed an intermediate phenotype. Tritiated thymidine incorporation studies were performed with multiple wtHSP27 and muHSP27 clones and the results compared with 11 vector control clones. The results showed an average increase in growth rate for the wtHSP27 cells of 3.0 +/- 0.6 times. The growth rate of eight muHSP27 clones showed a slight decrease. Estradiol treatment of endothelial cells resulted in an increase in both bovine and human HSP27, with peak expression at 100 nM. Treatment of the vector-transfected cells with 100 nM estradiol resulted in a 1.44 +/- 0.18 fold increase in growth rate, which was blocked by expression of muHSP27. These data demonstrate a role for HSP27 in controlling the growth rate of endothelial cells in an estrogen-responsive manner.
Subject(s)
Arteries/growth & development , Endothelium, Vascular/growth & development , Heat-Shock Proteins/biosynthesis , Actins/analysis , Animals , Arteries/cytology , Arteries/drug effects , CHO Cells , Cattle , Cells, Cultured , Cellular Senescence , Cloning, Molecular , Cricetinae , Dose-Response Relationship, Drug , Endothelium, Vascular/cytology , Endothelium, Vascular/drug effects , Estradiol/pharmacology , Heat-Shock Proteins/genetics , Humans , Immunoblotting , Isoelectric Focusing , Pinocytosis , Recombinant Proteins/biosynthesis , Selection, Genetic , TransfectionABSTRACT
Phosphorylation of heat shock protein 27 (HSP27) can modulate actin filament dynamics in response to growth factors. During heat shock, HSP27 is phosphorylated at the same sites and by the same protein kinase as during mitogenic stimulation. This suggests that the same function of the protein may be activated during growth factor stimulation and the stress response. To determine the role of HSP27 phosphorylation in the heat shock response, several stable Chinese hamster cell lines that constitutively express various levels of the wild-type HSP27 (HU27 cells) or a nonphosphorylatable form of human HSP27 (HU27pm3 cells) were developed. In contrast to HU27 cells, which showed increased survival after heat shock, HU27pm3 cells showed only slightly enhanced survival. Evidence is presented that stabilization of microfilaments is a major target of the protective function of HSP27. In the HU27pm3 cells, the microfilaments were thermosensitized compared with those in the control cells, whereas wild-type HSP27 caused an increased stability of these structures in HU27 cells. HU27 but not HU27pm3 cells were highly resistant to cytochalasin D treatment compared with control cells. Moreover, in cells treated with cytochalasin D, wild-type HSP27 but not the phosphorylated form of HSP27 accelerated the reappearance of actin filaments. The mutations in human HSP27 had no effect on heat shock-induced change in solubility and cellular localization of the protein, indicating that phosphorylation was not involved in these processes. However, induction of HSP27 phosphorylation by stressing agents or mitogens caused a reduction in the multimeric size of the wild-type protein, an effect which was not observed with the mutant protein. We propose that early during stress, phosphorylation-induced conformational changes in the HSP27 oligomers regulate the activity of the protein at the level of microfilament dynamics, resulting in both enhanced stability and accelerated recovery of the filaments. The level of protection provided by HSP27 during heat shock may thus represent the contribution of better maintenance of actin filament integrity to overall cell survival.
Subject(s)
Actin Cytoskeleton/metabolism , Actins/metabolism , Heat-Shock Proteins/metabolism , Hot Temperature , Actin Cytoskeleton/ultrastructure , Animals , Cell Compartmentation , Cells, Cultured , Cricetinae , Cricetulus , In Vitro Techniques , Intracellular Signaling Peptides and Proteins , Macromolecular Substances , Phosphorylation , Protein Binding , Protein Serine-Threonine Kinases/metabolismABSTRACT
We recently reported that overexpression of heat shock protein 27 (HSP27) in rodent fibroblasts increases the stability of stress fibers during hyperthermia and partially prevents actin depolymerization during exposure to cytochalasin D (Lavoie, J.N., Gingras-Breton, G., Tanguay, R. M., and Landry, J. (1993) J. Biol. Chem. 268, 3420-3429). Because HSP27 is a ubiquitous target of phosphorylation upon cell stimulation with a variety of growth factors and agents that affect cellular differentiation, we examined the role of HSP27 phosphorylation in regulating actin filament dynamics. Here we show that HSP27 is enriched at the leading edge of polarized fibroblasts. HSP27 is localized in lamellipodia and membrane ruffles where most actin polymerization occurs. We developed Chinese hamster cell lines that constitutively overexpressed either human HSP27 or a nonphosphorylatable mutant form of the protein. Overexpression of HSP27 caused an increased concentration of filamentous actin (F-actin) at the cell cortex and elevated pinocytotic activity. In contrast, overexpression of the non-phosphorylatable mutant form of HSP27 reduced cortical F-actin concentration and decreased pinocytosis activity relative to control cells. Mitogenic stimulation of fibroblasts resulted in a rapid polymerization of submembranous actin filaments. HSP27 enhanced growth factor-induced F-actin accumulation, whereas mutant HSP27 exerted a dominant negative effect and inhibited this response to growth factors. Thus, HSP27 is a component of a signal transduction pathway that can regulate microfilament dynamics.
Subject(s)
Actins/metabolism , Heat-Shock Proteins/metabolism , Pinocytosis , Animals , Cell Differentiation/drug effects , Cell Line , Cricetinae , Cricetulus , Fibroblast Growth Factors/pharmacology , Fibroblasts/cytology , Fibroblasts/drug effects , Fibroblasts/metabolism , Hot Temperature , Humans , Phosphorylation , Signal Transduction , Thrombin/pharmacologySubject(s)
Adenoma, Bile Duct/secondary , Bile Duct Neoplasms/pathology , Bile Ducts, Intrahepatic , Neoplasm Seeding , Skin Neoplasms/secondary , Adenoma, Bile Duct/pathology , Biopsy , Catheterization/adverse effects , Cholangiography , Drainage/adverse effects , Humans , Male , Middle Aged , Skin/pathology , Skin Neoplasms/pathology , Time FactorsSubject(s)
Laser Therapy , Skin Diseases/surgery , Humans , Laser Therapy/trends , Skin Diseases/pathologyABSTRACT
The progressive differentiation of both normal rat osteoblasts and HL-60 promyelocytic leukemia cells involves the sequential expression of specific genes encoding proteins that are characteristic of their respective developing cellular phenotypes. In addition to the selective expression of various phenotype marker genes, several members of the heat shock gene family exhibit differential expression throughout the developmental sequence of these two cell types. As determined by steady state mRNA levels, in both osteoblasts and HL-60 cells expression of hsp27, hsp60, hsp70, hsp89 alpha, and hsp89 beta may be associated with the modifications in gene expression and cellular architecture that occur during differentiation. In both differentiation systems, the expression of hsp27 mRNA shows a 2.5-fold increase with the down-regulation of proliferation while hsp60 mRNA levels are maximal during active proliferation and subsequently decline post-proliferatively. mRNA expression of two members of the hsp90 family decreases with the shutdown of proliferation, with a parallel relationship between hsp89 alpha mRNA levels and proliferation in osteoblasts and a delay in down-regulation of hsp89 alpha mRNA levels in HL-60 cells and of hsp89 beta mRNA in both systems. Hsp70 mRNA rapidly increases, almost twofold, as proliferation decreases in HL-60 cells but during osteoblast growth and differentiation was only minimally detectable and showed no significant changes. Although the presence of the various hsp mRNA species is maintained at some level throughout the developmental sequence of both osteoblasts and HL-60 cells, changes in the extent to which the heat shock genes are expressed occur primarily in association with the decline of proliferative activity. The observed differences in patterns of expression for the various heat shock genes are consistent with involvement in mediating a series of regulatory events functionally related to the control of both cell growth and differentiation.
Subject(s)
Cell Differentiation/genetics , Heat-Shock Proteins/genetics , Osteoblasts/cytology , Animals , Blotting, Northern , Cells, Cultured , Humans , Kinetics , Leukemia, Promyelocytic, Acute , Osteoblasts/metabolism , RNA, Messenger/genetics , Rats , Tumor Cells, CulturedABSTRACT
The intracellular concentration of the 27-kDa mammalian heat shock protein, HSP27, increases several-fold after heat and other metabolic stresses and is closely associated with the acquisition of thermotolerance. Posttranslational modifications may also affect the function of HSP27. Heat shock of HeLa cell cultures, or treatment with arsenite, phorbol ester, or tumor necrosis factor, caused a rapid phosphorylation of preexisting HSP27 and the appearance of three phosphorylated isoforms, HSP27 B, C, and D. Digestion with trypsin and fractionation of the peptides by reverse phase high performance liquid chromatography revealed three 32P-labeled phosphopeptides. Microsequence analysis identified peak I as Ala76-Leu77-Ser78-Arg79 and peak II as Gln80-Leu81-Ser82-Ser83-Gly84-Val85- Ser86-Glu87-Ile88-Arg89; peak III contained the undigested peptide pair Ala76-Arg89. Ser82 was the major site and Ser78 the minor site of phosphorylation. Mutant proteins with Ser78 or Ser82 altered to glycine or Ser78-Ser82 double mutants were phosphorylated to reduced extents in vivo after heat or arsenite treatment. Ser78 and Ser82 (and Ser15) occur in the sequence motif RXXS, which is recognized by ribosomal protein S6 kinase II. Mitogenic stimulation of serum-deprived, Go-arrested Chinese hamster cells with serum, thrombin, or fibroblast growth factor also stimulated phosphorylation of HSP27 Ser78 and Ser82, and mitogenic stimulation and heat shock activated protein kinase activities that phosphorylated HSP27 and protein S6 in vitro. These results suggest that HSP27 may exert phosphorylation-activated functions linked with growth signaling pathways in unstressed cells. A homeostatic function at this level could protect cells from adverse effects of signal transduction systems which may be activated inappropriately during stress.
Subject(s)
Arsenites , Heat-Shock Proteins/metabolism , Protein Kinases/metabolism , Serine/metabolism , Sodium Compounds , Amino Acid Sequence , Animals , Arsenic/pharmacology , Blotting, Western , Chromatography, High Pressure Liquid , Cricetinae , Cricetulus , Electrophoresis, Polyacrylamide Gel , Enzyme Activation , Fibroblast Growth Factors/metabolism , HeLa Cells , Humans , Mitogens , Molecular Sequence Data , Phosphorylation/drug effects , Protein Processing, Post-Translational , Ribosomal Protein S6 Kinases , Tetradecanoylphorbol Acetate/pharmacology , Thrombin/metabolism , Trypsin/chemistry , Tumor Necrosis Factor-alpha/pharmacologyABSTRACT
Expression of an estrogen-regulated protein known as the 27,000-d heat-shock or stress-response protein (srp-27) was evaluated in human breast carcinomas and established breast cancer cell lines. Results obtained by Northern and Western blot analyses and immunohistochemical methods were concordant. Immunohistochemical assessment of srp-27 expression in 300 breast carcinomas (with median patient follow-up of 8 years) was performed. Twenty-six percent of lymph node-negative and 45% of lymph node-positive tumors were overexpressors. Univariate analysis demonstrated significant correlations between srp-27 overexpression and estrogen receptor (ER) content, pS2 protein expression, nodal metastases, advanced T stage, lymphatic/vascular invasion, and a shorter disease-free survival period (but not a shorter overall survival) for the study population as a whole. Regression tree analysis showed that srp-27 expression was an independent prognostic indicator for disease-free survival only in patients with one to three positive lymph nodes. The Cox proportional hazards model confirmed the independent prognostic significance of nodal involvement, T stage, and ER content but failed to recognize srp-27 overexpression as a significant independent parameter predictive of patient outcome in the patient population as a whole. The observed associations between srp-27 overexpression and more aggressive tumors suggest a biologic role for srp-27 in human breast carcinomas.
Subject(s)
Breast Neoplasms/chemistry , Heat-Shock Proteins/analysis , Neoplasm Proteins/analysis , Blotting, Western , Breast Neoplasms/mortality , Breast Neoplasms/pathology , Female , Gene Expression Regulation, Neoplastic , Humans , Immunohistochemistry , Prognosis , Proportional Hazards Models , RNA, Messenger/analysis , RNA, Neoplasm/analysis , Regression Analysis , Survival Rate , Tumor Cells, CulturedABSTRACT
A major component of the regulation of histone protein synthesis during the cell cycle is the modulation of the half-life of histone mRNA. We have uncoupled transcriptional and posttranscriptional regulation by using a Drosophila hsp70-human H3 histone fusion gene that produces a marked human H3 histone mRNA upon heat induction. Transcription of this gene can be switched on and off by raising and lowering cell culture temperatures, respectively. HeLa cell lines containing stably integrated copies of the fusion gene were synchronized by double thymidine block. Distinct populations of H3 histone mRNA were produced by heat induction in early S-phase, late S-phase, or G2-phase cells, and the stability of the induced H3 histone mRNA was measured. The H3 histone mRNA induced during early S phase decayed with a half-life of 110 min, whereas the same transcript induced during late S phase had a half-life of 10 to 15 min. The H3 histone mRNA induced in non-S-phase cells is more stable than that induced in late S phase, with a half-life of 40 min. Thus, the stability of histone mRNA is actively regulated throughout the cell cycle. Our results are consistent with an autoregulatory model in which the stability of histone mRNA is determined by the level of free histone protein in the cytoplasm.