RESUMO
RESUMEN: El trauma maxilofacial por proyectil balístico corresponde a un escenario desafiante para los servicios de alta complejidad debido a su alta mortalidad y morbilidad, asociando gran costo en insumos, hospitalización y recursos, en contraste con la funcionalidad hacia una inserción laboral eficiente. En este sentido la cirugía de reconstrucción se relaciona con el daño presentado en los tejidos blandos y duros, siendo clasificada en etapa inmediata (reducción abierta y fijación con osteosintesis) y/o mediata en donde el uso de tutores externos continúa siendo una propuesta válida. Reporte de un paciente masculino de 38 años, que ingresa por trauma balístico maxilofacial con daño extenso en tejido blando y conminución en cuerpo de mandíbula, siendo tratado de manera mediata por estabilización de tutores externos y posterior reconstrucción con injerto autólogo no vascularizado; presentándose complicación intraoperatoria de comunicación de acceso extraoral con intraoral; cerrado con injerto loco regional de cuerpo adiposo de mejilla. Paciente presenta evolución favorable. Se realizó una revisión de literatura en relación al uso de cuerpo adiposo de mejilla en cirugía maxilofacial reconstructiva. El uso de tutores externos se presenta como una alternativa válida y favorable para traumatismos con daño extenso en tejido blando y duro. El uso de cuerpo adiposo de mejilla se reporta en variados usos en cirugía oral y maxilofacial, sin embargo, su uso como injerto locoregional para cierre de procesos que requieren ser injertados es escaso; planteándose como una propuesta en este reporte.
ABSTRACT: Ballistic projectile maxillofacial trauma corresponds to a challenging scenario for highly complex services due to high mortality and morbidity, associating high cost in supplies, hospitalization and resources, in contrast to the functionality towards efficient labor insertion. In this sense, reconstruction surgery is related to the damage presented in the soft and hard tissues, being classified in the immediate stage (open reduction and fixation with osteosynthesis) and / or mediate where the use of external tutors continues to be a valid proposal. Report of a 38-year-old male patient admitted for maxillofacial ballistic trauma with extensive soft tissue damage and comminution in the mandible body, being treated mediate by stabilization of external tutors and subsequent reconstruction with a non- autologous graft. vascularized; presenting intraoperative complication of communication between extraoral and intraoral access; closed with a locoregional flap of the adipose body of the cheek. The patient presents a favorable evolution. A literature review was carried out in relation to the use of the adipose body of the cheek in reconstructive maxillofacial surgery. The use of external tutors is presented as a valid and favorable alternative for trauma with extensive damage to soft and hard tissue. The use of the adipose body of the cheek is reported in various uses in oral and maxillofacial surgery, however, its use as a locoregional graft for closing processes that require grafting is scarce; it is presented as a proposal in this report.
RESUMO
Lung cancer is localized in the upper lobes in more than half of the cases. The risk of tumor infiltration of centrally located structures, such as bronchi and vessels are enhanced due to the anatomic topography. Pneumonectomy competes with sleeve resection for the surgical resection of centrally located tumors. The present review deals with the question if pneumonectomy should be considered as an alternative to sleeve resection for the treatment of lung cancer. Primary pneumonectomy does not provide any advantage even in advanced nodal disease. Extended lymph node dissection is not a contraindication for sleeve resections. Local recurrence rate is lower after sleeve resections despite the same radicality for both surgical treatment options. Mortality and morbidity rates are significantly lower for sleeve resections. Sleeve resections are associated with prolonged survival and better quality of life even in elderly patients.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/cirurgia , Neoplasias Pulmonares/cirurgia , Tratamentos com Preservação do Órgão/métodos , Pneumonectomia/métodos , Fatores Etários , Idoso , Brônquios/patologia , Brônquios/cirurgia , Carcinoma Pulmonar de Células não Pequenas/mortalidade , Carcinoma Pulmonar de Células não Pequenas/patologia , Humanos , Pulmão/patologia , Neoplasias Pulmonares/mortalidade , Neoplasias Pulmonares/patologia , Excisão de Linfonodo , Metástase Linfática/patologia , Invasividade Neoplásica , Estadiamento de Neoplasias , Tratamentos com Preservação do Órgão/mortalidade , Pneumonectomia/mortalidade , Artéria Pulmonar/patologia , Artéria Pulmonar/cirurgia , Veias Pulmonares/patologia , Veias Pulmonares/cirurgia , Qualidade de Vida , Análise de SobrevidaRESUMO
Non-traumatic intradiploic arachnoid cyst is a rare condition. We describe a young man with typical trigeminal neuralgia and intradiploic arachnoid cyst at the greater wing of the sphenoid. The patient was successfully treated with medical therapy. To our knowledge, this is the first case report of a possible correlation between trigeminal neuralgia and intraosseous arachnoid cyst. We describe the clinical case, the possible pathogenetic mechanism and briefly review the literature.
RESUMO
Regulation of the RET gene is highly specific during embryo development and is strictly tissue-specific. Control of transcription depends on mechanisms influenced by epigenetic processes, in particular, histone acetylation at regions flanking the 5' end of the gene. Since the RET gene is mapped in the pericentromeric region of the human chromosome 10, the implication of epigenetic processes is even more striking and worth to be investigated in an extended chromosomal tract. One experimental approach to study the chromatin status in relationship with gene transcription is to assess the replication timing, which we did by using fluorescent in situ hybridization in cells expressing or not expressing the RET gene. By using probes spanning a 700-kb genomic region from the RET locus toward the centromere, we found a relationship between RET expression and early replication. Different patterns were observed between cells naturally expressing RET and cells induced to expression of RET by treatment with sodium butyrate, an inhibitor of histone deacetylases. Three-dimensional analysis of the nuclear localization of fluorescent signals by confocal microscopy showed difference of localization between the RET probe and a probe for a housekeeping gene, G3PDH, located at 12p13.3, in cells that do not express RET, in accordance with previous data for other genes and chromosomal regions. However, RET-expressing cells showed a localization of signals which was not consistent with that expected for expressed genes.
Assuntos
Núcleo Celular/genética , Centrômero/genética , Cromossomos Humanos Par 10/genética , Replicação do DNA/genética , Regulação da Expressão Gênica/genética , Proteínas Proto-Oncogênicas/genética , Receptores Proteína Tirosina Quinases/genética , Butiratos/farmacologia , Linhagem Celular Tumoral , Núcleo Celular/metabolismo , Centrômero/metabolismo , DNA Complementar/genética , Inibidores Enzimáticos/farmacologia , Epigênese Genética/genética , Genes Reguladores/genética , Inibidores de Histona Desacetilases , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Humanos , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-ret , Receptores Proteína Tirosina Quinases/metabolismoRESUMO
Among unusual abnormalities of the lumbar spine reported since the introduction of Computed Tomography (CT), the presence of gas lucency in the spinal canal, known as vacuum phenomenon, is often demonstrated. On the contrary, epidural gas pseudocyst compressing a nerve root in patients with a lateral disc herniation has rarely been reported. We report a case of a 44-year-old man who experienced violent low back pain and monolateral sciatica, exacerbated by orthostatic position, one week before admission. A lumbosacral spine CT showed the presence of vacuum phenomenon associated with a degenerated disc material and a capsulated epidural gas collection with evidence of root compression. A microsurgical interlaminar approach was carried out and, before the posterior longitudinal ligament was entered, a spherical "bubble" compressing the nerve roots was observed. The capsulated pseudocyst was dissected out, peeled off and excised en bloc. A large part of the posterior longitudinal ligament and the lateral disc herniation were removed. Postoperatively the patient was completely free of symptoms. The mechanism of exacerbation of pain was probably due to the increased radicular compression in the upright posture and, besides the presence of a lateral disc herniation, could be related to a pneumatic squeezing of gas from the intervertebral space into the well capsulated sac by the solicitated L4-L5 motion segment. Histological study of the wall of the pseudocyst showed the presence of fibrous tissue identical to the ligament. We conclude that, in case of a lumbar disc herniation, it is recommended to perform a complete microdiscectomy and an accurate removal of the involved portion of posterior longitudinal ligament in order to prevent pseudocystic formations.
Assuntos
Cistos/complicações , Gases , Ligamentos Longitudinais/patologia , Síndromes de Compressão Nervosa/etiologia , Adulto , Dor nas Costas/etiologia , Espaço Epidural , Humanos , Deslocamento do Disco Intervertebral/diagnóstico por imagem , Deslocamento do Disco Intervertebral/cirurgia , Vértebras Lombares , Masculino , Síndromes de Compressão Nervosa/diagnóstico por imagem , Tomografia Computadorizada por Raios XRESUMO
Many different unique functions have been attributed to lactoferrin (Lf), including DNA and RNA binding, and transport into the nucleus, where Lf binds to specific sequences and activates transcription. A pentapeptide, Gly-Arg-Arg-Arg-Arg, corresponding to a region of the N-terminal portion of human Lf rich in basic amino acids, was synthesized and its intracellular localization was investigated. Peptide internalization was assayed using the rhodaminated form of the same molecule. This N-terminal peptide sequence is able to be internalized within less than 10 min at concentration as low as 1 microM, and its intracellular localization is nuclear, mainly nucleolar. Similar behaviour was observed using peptides composed of either all l or d amino acids, the last one being a retro-inverse peptide. The internalization process does not involve an endocytotic pathway, since no inhibition of the uptake was observed at 4 degrees C. The kinetics of peptide internalization was also evaluated. The internalization properties of such a short Lf pentapeptide have been assayed for its ability to transport peptide nucleic acids (PNAs) inside cells in order to improve their efficacy. The abundant transmembrane transport and nuclear localization of the proposed peptide, deriving from hLf and, for the first time, identified as a nuclear localization signal, could be used as an alternative strategy to tackle the unsolved problem of intracellular accumulation of antisense and antigene drugs and for the development of new pharmacological tools.
Assuntos
Núcleo Celular/metabolismo , Lactoferrina/metabolismo , Sinais de Localização Nuclear/metabolismo , Ácidos Nucleicos Peptídicos/metabolismo , Motivos de Aminoácidos , Nucléolo Celular/metabolismo , Endocitose , Corantes Fluorescentes/química , Humanos , Lactoferrina/química , Mimetismo Molecular , Ácidos Nucleicos Peptídicos/química , Rodaminas/química , Temperatura , Células Tumorais CultivadasRESUMO
The release of amphoterin by murine erythroleukaemia cells exposed to the chemical inducer hexamethylenebisacetamide represents an essential step for the process of their terminal differentiation. Once exported in the culture medium, amphoterin undergoes limited proteolysis, catalysed by a serine proteinase also secreted by stimulated cells. The isolated proteinase is responsible for degradation of amphoterin, with the production of a 10-amino-acid-residue fragment, specifically retaining the cell-differentiation-stimulating activity of the native protein molecule. This peptide does not express other properties of amphoterin, such as protein kinase C-stimulating activity or systemic toxicity. These findings define a selective mechanism accounting for extracellular amphoterin functional maturation.
Assuntos
Proteínas de Transporte/metabolismo , Diferenciação Celular/efeitos dos fármacos , Proteínas de Grupo de Alta Mobilidade/metabolismo , Fragmentos de Peptídeos/metabolismo , Fragmentos de Peptídeos/farmacologia , Animais , Biomarcadores Tumorais/metabolismo , Cátions Bivalentes/farmacologia , Proteína HMGB1 , Cinética , Leucemia Eritroblástica Aguda , Metais/farmacologia , Camundongos , Inibidores de Proteases/farmacologia , Proteína Quinase C/metabolismo , Proteínas Recombinantes/metabolismo , Células Tumorais CultivadasRESUMO
We have previously reported that, in neuroblastoma LAN-5 cells, calpastatin is in an aggregated state, close to the cell nucleus [de Tullio, Passalacqua, Averna, Salamino, Melloni and Pontremoli (1999) Biochem. J. 343, 467-472]. In the present paper, we demonstrate that aggregated calpastatin is predominantly in a phosphorylated state. An increase in intracellular free [Ca2+] induces both dephosphorylation of calpastatin, through the action of a phosphoprotein phosphatase, and its redistribution as a soluble inhibitor species. cAMP, but not PMA-induced phosphorylation, reverses calpastatin distribution favouring its aggregation. This intracellular reversible mechanism, regulating the level of cytosolic calpastatin, could be considered a strategy through which calpain can escape calpastatin inhibition, especially during earlier steps of its activation process.
Assuntos
Proteínas de Ligação ao Cálcio/metabolismo , Cromatografia por Troca Iônica , AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Humanos , Fosforilação , Proteína Quinase C/metabolismo , Células Tumorais CultivadasRESUMO
Neuroblastoma LAN-5 cells exposed to retinoic acid cease to multiply and extend neurite outgrowths acquiring a neuronal phenotype. We now report that protein kinase C-theta; (PKC-theta;) isozyme is involved in this differentiation process due to the following findings: (i) PKC-theta; is expressed by LAN-5 cells as a nuclear and perinuclear protein; (ii) cell stimulation with retinoic acid promotes in a large increase in the expression level of the kinase and its intracellular redistribution; and (iii) a PKC-theta; antisense oligonucleotide reduces at the same time the expression level of the kinase and the cell response to retinoic acid. Altogether these data are consistent with a specific role played by PKC-theta; in the differentiation program of neuronal cells.
Assuntos
Diferenciação Celular/fisiologia , Isoenzimas/genética , Isoenzimas/metabolismo , Oligodesoxirribonucleotídeos Antissenso/farmacologia , Proteína Quinase C/genética , Proteína Quinase C/metabolismo , Diferenciação Celular/efeitos dos fármacos , Núcleo Celular/enzimologia , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Humanos , Neuroblastoma , Reação em Cadeia da Polimerase , Proteína Quinase C-theta , RNA Mensageiro/genética , Transcrição Gênica/efeitos dos fármacos , Tretinoína/farmacologia , Células Tumorais CultivadasRESUMO
In this study we demonstrate that the rat pheochromocytoma PC12 cell line expresses the novel protein kinase C isozyme designated PKC-θ. The isozyme is almost completely localized in the nuclear compartment of proliferating cells. Following stimulation with the nerve growth factor, PKC-θ is redistributed into the cytoplasm and the outgrowing neurite processes, mostly as a cytoskeletal associated kinase. This event is accompanied by an eightfold increase in the expression level and by the appearance of specific modifications of PKC-θ molecule. Conversely, the kinase is down-regulated once cells reach the terminally differentiated state displaying a neuron-like phenotype. These data suggest a functional role for the kinase in the regulation of cytoskeletal modeling along the multistage differentiation process of PC12 cells.
Assuntos
Diferenciação Celular , Isoenzimas/metabolismo , Neurônios/citologia , Neurônios/enzimologia , Proteína Quinase C/metabolismo , Animais , Transporte Biológico/efeitos dos fármacos , Western Blotting , Diferenciação Celular/efeitos dos fármacos , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/enzimologia , Núcleo Celular/metabolismo , Citocalasina B/farmacologia , Citoesqueleto/efeitos dos fármacos , Citoesqueleto/enzimologia , Citoesqueleto/metabolismo , Regulação para Baixo/efeitos dos fármacos , Imunofluorescência , Fator de Crescimento Neural/farmacologia , Neuritos/efeitos dos fármacos , Neuritos/enzimologia , Neurônios/efeitos dos fármacos , Células PC12 , Proteína Quinase C-theta , RatosRESUMO
Localization of the two main components of the Ca(2+)-dependent proteolytic system has been investigated in human neuroblastoma LAN-5 cells. Using a monoclonal antibody which recognizes the N-terminal calpastatin domain, it has been shown that this inhibitory protein is almost completely confined in two granule-like structures not surrounded by membranes. Similar calpastatin distribution has been found in other human and in murine cell types, indicating that aggregation of calpastatin is a general property and not an exclusive characteristic of neuronal-like cells. The existence of such calpastatin aggregates is confirmed by the kinetics of calpastatin-activity release during rat liver homogenization, which does not correspond to the rate of appearance of cytosolic proteins or to the disruption of membrane-surrounded organelles. Calpastatin distribution is affected by the intracellular increase in free Ca(2+), which results in calpastatin progressively becoming a soluble protein. However, calpain is distributed in the soluble cell fraction and, in activating conditions, partially accumulates on the plasma membrane. Similar behaviour has been observed in calpastatin localization in LAN-5 cells induced with retinoic acid, suggesting that the proteolytic system is activated during the differentiation process of these cells. The involvement of calpastatin in controlling calpain activity, rather than its activation process, and the utilization of changes in calpastatin localization as a marker of activation of the system is discussed.
Assuntos
Proteínas de Ligação ao Cálcio/metabolismo , Calpaína/metabolismo , Neurônios/enzimologia , Neurônios/metabolismo , Animais , Calcimicina/farmacologia , Cálcio/metabolismo , Diferenciação Celular/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Membrana Celular/enzimologia , Membrana Celular/metabolismo , Permeabilidade da Membrana Celular , Citosol/efeitos dos fármacos , Citosol/enzimologia , Citosol/metabolismo , Difusão , Endopeptidases/metabolismo , Ativação Enzimática/efeitos dos fármacos , Humanos , Fígado/enzimologia , Fígado/metabolismo , Camundongos , Neurônios/citologia , Neurônios/efeitos dos fármacos , Ratos , Solubilidade , Tretinoína/farmacologia , Células Tumorais CultivadasRESUMO
Protein kinase C-theta is a member of the n-protein kinase C subfamily that in mitotic cells translocates to centrosomes and kinetochores. Although this kinase is expressed in comparable amounts in murine erythroleukaemia cells during the interphase or metaphase, when localized in the mitotic structures, it selectively phosphorylates a 66 kDa protein, also associated to chromosomes. Moreover, protein kinase C-theta immunoprecipitated from cells at the metaphase results four times more active in the absence of lipid cofactors as compared with the kinase obtained from cells in the interphase. This activation is accomplished by interaction of protein kinase C-theta with a protein factor which also promotes an increased autophosphorylation of the kinase. These findings indicate that in the mitotic phase of the cell cycle, protein kinase C-theta recognizes a protein factor which operates as a positive modulator of the kinase activity in the absence lipids.
Assuntos
Isoenzimas/metabolismo , Leucemia Eritroblástica Aguda/enzimologia , Mitose/fisiologia , Proteína Quinase C/metabolismo , Animais , Cromossomos/enzimologia , Camundongos , Proteínas Nucleares/isolamento & purificação , Fosforilação , Proteína Quinase C-theta , Fuso Acromático/enzimologia , Células Tumorais CultivadasRESUMO
This is the first case of multiple (triple) pituitary micro-adenomas documented by magnetic resonance imaging (MRI) in a living patient and treated by a transsphenoidal microsurgical approach. The patient, a 37-year-old woman, complained of a long history of bifrontal headache, weight gain and oligomenorrhea. Physical examination revealed moderate hirsutism and a slight fat pad overlying the vertebrae. Routine laboratory studies and endocrinological biochemical investigations were normal. A gadolinium-enhanced MRI of the pituitary region revealed three intrapituitary micro-adenomas. A transsphenoidal microsurgical approach to the pituitary gland was carried out and micro-adenomas were completely removed one at a time. One year follow-up showed complete resolution of clinical symptoms and signs and normal biochemical parameters of pituitary function.
Assuntos
Adenoma/cirurgia , Microcirurgia/métodos , Neoplasias Hipofisárias/cirurgia , Adulto , Feminino , HumanosAssuntos
Vértebras Cervicais/cirurgia , Compressão da Medula Espinal/cirurgia , Neoplasias da Coluna Vertebral/cirurgia , Timoma/secundário , Neoplasias do Timo/cirurgia , Adulto , Vértebras Cervicais/patologia , Feminino , Humanos , Miastenia Gravis/patologia , Miastenia Gravis/cirurgia , Compressão da Medula Espinal/patologia , Neoplasias da Coluna Vertebral/patologia , Timoma/patologia , Timoma/cirurgia , Neoplasias do Timo/patologiaRESUMO
CD38, a transmembrane glycoprotein widely expressed in vertebrate cells, is a bifunctional ectoenzyme catalyzing the synthesis and hydrolysis of cyclic ADP-ribose (cADPR). cADPR is a universal second messenger that releases calcium from intracellular stores. Since cADPR is generated by CD38 at the outer surface of many cells, where it acts intracellularly, increasing attention is paid to addressing this topological paradox. Recently, we demonstrated that CD38 is a catalytically active, unidirectional transmembrane transporter of cADPR, which then reaches its receptor-operated intracellular calcium stores. Moreover, CD38 was reported to undergo a selective and extensive internalization through non clathrin-coated endocytotic vesicles upon incubating CD38(+) cells with either NAD+ or thiol compounds: these endocytotic vesicles can convert cytosolic NAD into cADPR despite an asymmetric unfavorable orientation that makes the active site of CD38 intravesicular. Here we demonstrate that the cADPR-generating activity of the endocytotic vesicles results in remarkable and sustained increases of intracellular free calcium concentration in different cells exposed to either NAD+, or GSH, or N-acetylcysteine. This effect of CD38-internalizing ligands on intracellular calcium levels was found to involve a two-step mechanism: 1) influx of cytosolic NAD+ into the endocytotic vesicles, mediated by a hitherto unrecognized dinucleotide transport system that is saturable, bidirectional, inhibitable by 8-N3-NAD+, and characterized by poor dinucleotide specificity, low affinity, and high efficiency; 2) intravesicular CD38-catalyzed conversion of NAD+ to cADPR, followed by outpumping of the cyclic nucleotide into the cytosol and subsequent release of calcium from thapsigargin-sensitive stores. This unknown intracellular trafficking of NAD+ and cADPR based on two distinctive and specific transmembrane carriers for either nucleotide can affect the intracellular calcium homeostasis in CD38(+) cells.
Assuntos
Antígenos CD , Antígenos de Diferenciação/metabolismo , Cálcio/metabolismo , NAD+ Nucleosidase/metabolismo , NAD/metabolismo , Transdução de Sinais , Células 3T3 , ADP-Ribosil Ciclase , ADP-Ribosil Ciclase 1 , Adenosina Difosfato Ribose/metabolismo , Animais , Transporte Biológico , Células HeLa , Humanos , Células Jurkat , Ligantes , Glicoproteínas de Membrana , Camundongos , Sistemas do Segundo MensageiroRESUMO
In this study we provide evidence that the protein kinase C (PKC)-straight theta isoenzyme is recruited on to the mitotic spindle in dividing murine erythroleukaemia (MEL) cells and associates specifically with centrosome and kinetochore structures. None of the other PKC isoenzymes (-alpha, -delta, -epsilon, -mu and -zeta) expressed by MEL cells shows this localization on the mitotic spindle. An identical subcellular distribution of PKC-straight theta is also observed in dividing murine P3 myeloma cells and human LAN-5 neuroblastoma cells, indicating that this PKC isoenzyme interacts with the mitotic apparatus in mammalian cells. In phorbol-ester-treated non-growing MEL cells, a rapid change in the intracellular distribution of PKC-straight theta occurs. Under these conditions, PKC-straight theta is translocated from the nuclear to the cytosolic cell compartment, an event that is accompanied by phosphorylation of the PKC-straight theta molecule and is followed by its down-regulation. The recovery of cell growth capacity results in the concomitant reappearance of PKC-straight theta. Furthermore, when MEL cells acquire the differentiated non-growing phenotype, the level of PKC-straight theta is reduced to less than 5%, suggesting that this PKC isoenzyme is no longer required. We propose that, unlike other members of the PKC family, PKC-straight theta may play a role in cell proliferation.
Assuntos
Centrossomo/enzimologia , Isoenzimas/metabolismo , Cinetocoros/enzimologia , Proteína Quinase C/metabolismo , Animais , Proteínas de Ciclo Celular/metabolismo , Divisão Celular , Regulação para Baixo , Camundongos , Fosforilação , Proteína Quinase C-theta , Acetato de Tetradecanoilforbol/farmacologia , Células Tumorais CultivadasRESUMO
Stimulated astrocytes specifically release large amounts of high-mobility group 1 protein into the extracellular medium. The identity of the released protein has been established on the basis of its biological activity on murine erythroleukaemia cells and by its immunoreactivity against a specific monoclonal antibody. High-mobility group 1 protein also plays an essential role in differentiation of LAN-5 neuroblastoma cells which, following stimulation with retinoic acid, express high-mobility group 1 protein on to the external surface of the plasma membrane. In retinoic acid-induced LAN-5 cells, high-mobility group 1 protein is not secreted but is accumulated in a membrane-bound form, particularly at the level of neurite outgrowths. These cells can also be induced to differentiate by high-mobility group 1 protein coated on the surface of the cell culture vessels. The specific function of the protein in this process is indicated by inhibition of cell differentiation by an anti-high-mobility group 1 protein antibody. The data are consistent with a role of high-mobility group 1 protein in promoting cell-cell interactions and in the development of nerve tissues.
Assuntos
Astrócitos/metabolismo , Neoplasias Encefálicas/patologia , Proteínas de Grupo de Alta Mobilidade/metabolismo , Neuroblastoma/patologia , Animais , Animais Recém-Nascidos , Astrócitos/efeitos dos fármacos , Bucladesina/farmacologia , Adesão Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Cromatografia de Afinidade , Eletroforese em Gel de Poliacrilamida , Humanos , Microscopia de Fluorescência , Ratos , Ratos Sprague-Dawley , Estimulação Química , Células Tumorais CultivadasRESUMO
We show here that murine erythroleukemia (MEL) cells, following induction with hexamethylene bisacetamide, accumulate high mobility group (HMG)1 protein onto the external surface of the cell in a membrane-associated form detectable by immunostaining with a specific anti-HMG1 protein antibody. This association is maximal at a time corresponding to cell commitment. At longer times, immunostainable cells are progressively reduced and become almost completely undetectable along with the appearance of hemoglobin molecules. Binding to MEL cells does not affect the native molecular structure of HMG1 protein. The type of functional correlation between HMG1 protein and MEL cell differentiation is suggested by the observation that if an anti-HMG1 protein antibody is added at the same time of the inducer almost complete inhibition of cell differentiation is observed, whereas if the antibody is added within the time period in which cells undergo through irreversible commitment, inhibition progressively disappears. A correlation between MEL cell commitment and the biological effect of HMG1 protein can thus be consistently suggested.
Assuntos
Diferenciação Celular , Membrana Celular/metabolismo , Eritrócitos/citologia , Proteínas de Grupo de Alta Mobilidade/metabolismo , Acetamidas/farmacologia , Animais , Anticorpos Monoclonais , Retículo Endoplasmático/metabolismo , Eritrócitos/metabolismo , Complexo de Golgi/metabolismo , Proteínas de Grupo de Alta Mobilidade/imunologia , Leucemia Eritroblástica Aguda , Camundongos , Células Tumorais CultivadasRESUMO
A high-mobility group 1 (HMG1) protein type isolated from murine erythroleukaemia (MEL) cells promotes acceleration of the differentiation process when added to a MEL cell culture together with the inducer hexamethylene bisacetamide. We now provide direct evidence that the presence of HMG1 protein in the extracellular medium is essential for terminal erythroid differentiation. An extracellular function for HMG1 protein in MEL cell is further supported by a demonstration that this protein is released from MEL cells exposed to the chemical inducer and that the addition of an anti-(HMG1 protein) monoclonal antibody to the cell culture inhibits the differentiation process almost completely. The release of HMG1 protein from MEL cells is modulated by compounds affecting cell calcium homoeostasis, such as a calcium ionophore or verapamil. In fact, in the presence of the ionophore an increased rate of differentiation is accompanied by an enhanced extracellular release of HMG1 protein, whereas in the presence of verapamil both phenomena are significantly decreased.
Assuntos
Diferenciação Celular/fisiologia , Proteínas de Grupo de Alta Mobilidade/fisiologia , Leucemia Eritroblástica Aguda/patologia , Acetamidas/farmacologia , Animais , Antineoplásicos/farmacologia , Calcimicina/farmacologia , Diferenciação Celular/efeitos dos fármacos , Camundongos , Células Tumorais CultivadasRESUMO
Murine erythroleukemia (MEL) cells, in addition to an mRNA coding for a 30 kDa high mobility group (HMG)-1 protein, contain an mRNA coding for a 6 kDa HMG1 protein having the following structural properties: (1) its primary structure has 90% homology with the N-terminal sequence of the 30 kDa HMG1 protein; (2) it contains a consensus region of the HMG1 protein family; (3) it is deprived of the cluster of acidic amino acids that characterizes the C-terminal region of the 30 kDa HMG1 protein. This novel small Mr HMG1 protein has been expressed in prokaryotic cells and tested to establish similarities and differences in activity compared to the homologous higher Mr HMG1 protein. It has been found that the low Mr HMG1 form is not released from MEL cells following induction to erythroid differentiation, but is still effective, although with much less efficiency, when added to the external medium, in promoting acceleration in the rate of MEL cell differentiation as well as in activation of alpha-protein kinase C. Altogether these results provide evidence for the presence in MEL cells of a multigene family that encodes at least two different HMG1-type sequences most presumably involved, at distinct cellular sites, in different functions although commonly related to the promotion of cell differentiation. Additional information can be considered concerning the relationship between the characteristic N-terminal sequence of HMG1 protein and the extracellular activity on MEL cell differentiation.