Assuntos
Inflamação , NF-kappa B/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Animais , Ativação Enzimática , Células HeLa , Humanos , Quinase I-kappa B , Proteínas I-kappa B/metabolismo , Inflamação/enzimologia , Inflamação/metabolismo , Camundongos , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt , Transdução de Sinais , Fator de Necrose Tumoral alfa/fisiologiaRESUMO
Phosphorylation of IkappaB by the IkappaB kinase (IKK) complex is a critical step leading to IkappaB degradation and activation of transcription factor NF-kappaB. The IKK complex contains two catalytic subunits, IKKalpha and IKKbeta, the latter being indispensable for NF-kappaB activation by pro-inflammatory cytokines. Although IKK is activated by phosphorylation of the IKKbeta activation loop, the physiological IKK kinases that mediate responses to extracellular stimuli remain obscure. Here we describe an IKK-related kinase, named NAK (NF-kappaB-activating kinase), that can activate IKK through direct phosphorylation. NAK induces IkappaB degradation and NF-kappaB activity through IKKbeta. Endogenous NAK is activated by phorbol ester tumour promoters and growth factors, whereas catalytically inactive NAK specifically inhibits activation of NF-kappaB by protein kinase C-epsilon (PKCepsilon). Thus, NAK is an IKK kinase that may mediate IKK and NF-kappaB activation in response to growth factors that stimulate PKCepsilon activity.
Assuntos
Proteínas Serina-Treonina Quinases/metabolismo , Sequência de Aminoácidos , Animais , Células COS , Linhagem Celular , Clonagem Molecular , Ativação Enzimática , Células HeLa , Humanos , Quinase I-kappa B , Luciferases/genética , Camundongos , Dados de Sequência Molecular , NF-kappa B/metabolismo , Fosforilação , Serina/metabolismo , Transcrição Gênica , Ubiquitinas/metabolismoRESUMO
NF-kappa B is a heterodimeric transcription factor that plays a key role in inflammatory and immune responses. In nonstimulated cells, NF-kappa B dimers are maintained in the cytoplasm through interaction with inhibitory proteins, the I kappa Bs. In response to cell stimulation, mainly by proinflammatory cytokines, a multisubunit protein kinase, the I kappa B kinase (IKK), is rapidly activated and phosphorylates two critical serines in the N-terminal regulatory domain of the I kappa Bs. Phosphorylated I kappa Bs are recognized by a specific E3 ubiquitin ligase complex and undergo polyubiquitination which targets them for rapid degradation by the 26S proteasome. NF-kappa B dimers, which are spared from degradation, translocate to the nucleus to activate gene transcription. There is strong biochemical and genetic evidence that the IKK complex, which consists of two catalytic subunits, IKK alpha and IKK beta, and a regulatory subunit, IKK gamma, is the master regulator of NF-kappa B-mediated innate immune and inflammatory responses. In the absence of IKK gamma, which normally connects IKK to upstream activators, no IKK or NF-kappa B activation can occur. Surprisingly, however, of the two catalytic subunits, only IKK beta is essential for NF-kappa B activation in response to proinflammatory stimuli. The second catalytic subunit, IKK alpha, plays a critical role in developmental processes, in particular formation and differentiation of the epidermis.
Assuntos
Citocinas/imunologia , Inflamação/imunologia , NF-kappa B/fisiologia , Proteínas Serina-Treonina Quinases/fisiologia , Transdução de Sinais/fisiologia , Animais , Humanos , Quinase I-kappa BRESUMO
The IkappaB kinase (IKK) complex is composed of three subunits, IKKalpha, IKKbeta, and IKKgamma (NEMO). While IKKalpha and IKKbeta are highly similar catalytic subunits, both capable of IkappaB phosphorylation in vitro, IKKgamma is a regulatory subunit. Previous biochemical and genetic analyses have indicated that despite their similar structures and in vitro kinase activities, IKKalpha and IKKbeta have distinct functions. Surprisingly, disruption of the Ikkalpha locus did not abolish activation of IKK by proinflammatory stimuli and resulted in only a small decrease in nuclear factor (NF)-kappaB activation. Now we describe the pathophysiological consequence of disruption of the Ikkbeta locus. IKKbeta-deficient mice die at mid-gestation from uncontrolled liver apoptosis, a phenotype that is remarkably similar to that of mice deficient in both the RelA (p65) and NF-kappaB1 (p50/p105) subunits of NF-kappaB. Accordingly, IKKbeta-deficient cells are defective in activation of IKK and NF-kappaB in response to either tumor necrosis factor alpha or interleukin 1. Thus IKKbeta, but not IKKalpha, plays the major role in IKK activation and induction of NF-kappaB activity. In the absence of IKKbeta, IKKalpha is unresponsive to IKK activators.
Assuntos
Apoptose/fisiologia , NF-kappa B/metabolismo , Proteínas Serina-Treonina Quinases/fisiologia , Animais , Sequência de Bases , Primers do DNA/genética , Feminino , Quinase I-kappa B , Interleucina-1/farmacologia , Fígado/anormalidades , Fígado/patologia , Camundongos , Camundongos Knockout , Fenótipo , Gravidez , Conformação Proteica , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/genética , Transdução de Sinais , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
IkappaB [inhibitor of nuclear factor kappaB (NF-kappaB)] kinase (IKK) phosphorylates IkappaB inhibitory proteins, causing their degradation and activation of transcription factor NF-kappaB, a master activator of inflammatory responses. IKK is composed of three subunits-IKKalpha and IKKbeta, which are highly similar protein kinases, and IKKgamma, a regulatory subunit. In mammalian cells, phosphorylation of two sites at the activation loop of IKKbeta was essential for activation of IKK by tumor necrosis factor and interleukin-1. Elimination of equivalent sites in IKKalpha, however, did not interfere with IKK activation. Thus, IKKbeta, not IKKalpha, is the target for proinflammatory stimuli. Once activated, IKKbeta autophosphorylated at a carboxyl-terminal serine cluster. Such phosphorylation decreased IKK activity and may prevent prolonged activation of the inflammatory response.
Assuntos
MAP Quinase Quinase Quinase 1 , Proteínas Serina-Treonina Quinases/metabolismo , Sequência de Aminoácidos , Substituição de Aminoácidos , Linhagem Celular , Proteínas de Ligação a DNA/metabolismo , Ativação Enzimática , Células HeLa , Sequências Hélice-Alça-Hélice , Humanos , Quinase I-kappa B , Proteínas I-kappa B , Interleucina-1/farmacologia , Zíper de Leucina , Dados de Sequência Molecular , Mutação , Fosforilação , Fosfosserina/metabolismo , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/genética , Transfecção , Fator de Necrose Tumoral alfa/farmacologia , Quinase Induzida por NF-kappaBRESUMO
The oligomeric IkappaB kinase (IKK) is composed of three polypeptides: IKKalpha and IKKbeta, the catalytic subunits, and IKKgamma, a regulatory subunit. IKKalpha and IKKbeta are similar in structure and thought to have similar function-phosphorylation of the IkappaB inhibitors in response to proinflammatory stimuli. Such phosphorylation leads to degradation of IkappaB and activation of nuclear factor kappaB transcription factors. The physiological function of these protein kinases was explored by analysis of IKKalpha-deficient mice. IKKalpha was not required for activation of IKK and degradation of IkappaB by proinflammatory stimuli. Instead, loss of IKKalpha interfered with multiple morphogenetic events, including limb and skeletal patterning and proliferation and differentiation of epidermal keratinocytes.
Assuntos
Desenvolvimento Embrionário e Fetal , Morfogênese , Proteínas Serina-Treonina Quinases/metabolismo , Anormalidades Múltiplas/enzimologia , Anormalidades Múltiplas/genética , Animais , Apoptose , Padronização Corporal , Osso e Ossos/anormalidades , Osso e Ossos/embriologia , Diferenciação Celular , Núcleo Celular/metabolismo , Células Cultivadas , Proteínas de Ligação a DNA/metabolismo , Dimerização , Ativação Enzimática , Células Epidérmicas , Epiderme/embriologia , Feminino , Marcação de Genes , Quinase I-kappa B , Proteínas I-kappa B , Queratinócitos , Deformidades Congênitas dos Membros/enzimologia , Masculino , Camundongos , Mutação , Fosforilação , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/genética , Pele/embriologia , Anormalidades da Pele/enzimologiaAssuntos
Proteínas I-kappa B , Imunidade , NF-kappa B/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Sequência de Aminoácidos , Animais , Evolução Biológica , Diferenciação Celular , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Ativação Enzimática , Células Epidérmicas , Humanos , Quinase I-kappa B , Modelos Biológicos , Dados de Sequência Molecular , Inibidor de NF-kappaB alfa , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/genética , Homologia de Sequência de AminoácidosRESUMO
In human obesity as well as in rat obesity models a decrease in spontaneous and stimulated GH secretion has been a constant finding. The presence of a decreased pituitary GH synthesis in diet-induced obese male rats was investigated and its possible relationship with obesity-related changes in peripheral hormones was analyzed. Cafeteria-diet-overfed obese male Wistar rats with body fat percentage above 30% had a significantly decreased pituitary GH mRNA transcript level assessed by both Northern blot and in situ hybridization, and a lower pituitary GH protein level as demonstrated by immunocytochemistry. The GH transcript level correlated negatively with the serum leptin and positively with the IGF-I concentration. No differences in circulating tri-iodothyronine, non-fasting insulin and corticosterone levels were found between overfed and control rats. GH release by cultured pituitary cells from overfed rats was comparable to that by cells prepared from control rats. In contrast, incubation of normal pituitary cells with serum from overfed rats for 3 days gave a significantly lower GH release than after incubation with serum from non-obese rats. In conclusion, cafeteria-diet-induced obese male Wistar rats have a decreased pituitary GH gene expression and a modifiable GH release in in vitro experiments. A possible role for peripheral circulating factors, like leptin and IGF-I, in decreasing the pituitary GH synthesis and release in obese rats is discussed.
Assuntos
Hormônio do Crescimento/metabolismo , Obesidade/fisiopatologia , Adeno-Hipófise/metabolismo , Animais , Northern Blotting , Composição Corporal , Células Cultivadas , Dieta , Expressão Gênica , Hormônio do Crescimento/análise , Hormônio do Crescimento/genética , Imuno-Histoquímica , Hibridização In Situ , Masculino , Obesidade/etiologia , Adeno-Hipófise/química , Radioimunoensaio , Ratos , Ratos Wistar , Taxa SecretóriaAssuntos
Proteínas Quinases JNK Ativadas por Mitógeno , MAP Quinase Quinase Quinase 1 , Quinases de Proteína Quinase Ativadas por Mitógeno , NF-kappa B/metabolismo , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Fator de Transcrição AP-1/metabolismo , Linhagem Celular , Ativação Enzimática , Células HeLa , Humanos , Quinase I-kappa B , MAP Quinase Quinase 4 , FosforilaçãoRESUMO
Here we report the characterization of 12 kb genomic DNA upstream of the human PIT1/GHF1 promoter. Different regions involved in the modulation of human PIT1/GHF1 gene expression were defined by transient transfection studies. Two regions, one proximal (-7.1/-2. 3) and one distal (-11.8/-10.9), presented an enhancer activity in pituitary cells when placed upstream of the SV40 promoter. The 0.9 kb distal region was analysed further and found to decrease the basal transcriptional activity of the human PIT1/GHF1 minimal promoter, indicating that this region behaves as a silencer for its own promoter. Three Pit-1/GHF-1-binding sites and two ubiquitous nuclear factor 1 (NF-1)-binding sites were identified by DNase I footprinting in the distal regulatory region. Deletion analysis indicated that NF-1 or NF-1-related protein(s) participate in the down-regulation of human PIT1/GHF1 gene expression by interacting with an NF-1-binding site within the distal regulatory region.
Assuntos
Proteínas Estimuladoras de Ligação a CCAAT , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica , Fatores de Transcrição/genética , Animais , Sequência de Bases , Sítios de Ligação , Pegada de DNA , Proteínas de Ligação a DNA/metabolismo , Desoxirribonuclease I/genética , Regulação para Baixo , Células HeLa , Humanos , Dados de Sequência Molecular , Fatores de Transcrição NFI , Proteínas Nucleares , Neoplasias Hipofisárias/patologia , Ratos , Sequências Reguladoras de Ácido Nucleico , Fator de Transcrição Pit-1 , Fatores de Transcrição/metabolismo , Transcrição Gênica , Células Tumorais Cultivadas , Proteína 1 de Ligação a Y-BoxRESUMO
Recently we purified a 900 kDa cytokine-responsive IkappaB kinase complex (IKK) and molecularly cloned one of its subunits, IKKalpha, a serine kinase. We now describe the molecular cloning and characterization of IKKbeta, a second subunit of the IKK complex. IKKbeta is 50% identical to IKKalpha and like it contains a kinase domain, a leucine zipper, and a helix-loop-helix. Although IKKalpha and IKKbeta can undergo homotypic interaction, they also interact with each other and the functional IKK complex contains both subunits. The catalytic activities of both IKKalpha and IKKbeta make essential contributions to IkappaB phosphorylation and NF-kappaB activation. While the interactions between IKKalpha and IKKbeta may be mediated through their leucine zipper motifs, their helix-loop-helix motifs may be involved in interactions with essential regulatory subunits.
Assuntos
Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/metabolismo , Sequência de Aminoácidos , Núcleo Celular/metabolismo , Clonagem Molecular , Ativação Enzimática , Células HeLa , Sequências Hélice-Volta-Hélice , Humanos , Quinase I-kappa B , Zíper de Leucina , Dados de Sequência Molecular , NF-kappa B/metabolismo , Fosforilação , Proteínas Serina-Treonina Quinases/genética , Fator de Transcrição RelARESUMO
Since GH stimulates the development and function of granulocytes, we investigated the expression of GH in granulocyte subsets. By immunocytochemistry, 25 +/- 7% of the human neutrophils were shown to express immunoreactive GH, whereas eosinophils were negative. Reversed transcription (RT)-PCR analysis demonstrated GH mRNA in neutrophils. Restriction analysis revealed that neutrophils express the GH-N gene but not the GH-V gene. Furthermore, we demonstrated by western blot analysis that neutrophils express an alternatively spliced variant of the pituitary transcription factor Pit-1, designated Pit-1b.
Assuntos
Proteínas de Ligação a DNA/biossíntese , Proteínas de Ligação a DNA/genética , Hormônio do Crescimento/biossíntese , Hormônio do Crescimento/genética , Neutrófilos/metabolismo , Hipófise/química , Fatores de Transcrição/biossíntese , Fatores de Transcrição/genética , Transcrição Gênica , Adenoma/química , Adenoma/patologia , Adulto , Western Blotting , Proteínas de Ligação a DNA/fisiologia , Regulação da Expressão Gênica , Variação Genética , Granulócitos/química , Granulócitos/citologia , Granulócitos/metabolismo , Hormônio do Crescimento/fisiologia , Humanos , Imuno-Histoquímica , Pessoa de Meia-Idade , Neutrófilos/química , Neutrófilos/citologia , Hipófise/citologia , Neoplasias Hipofisárias/química , Neoplasias Hipofisárias/patologia , Reação em Cadeia da Polimerase , RNA Mensageiro/análise , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Fator de Transcrição Pit-1 , Fatores de Transcrição/fisiologiaRESUMO
In human obesity, spontaneous and GRF stimulated growth hormone secretion have been shown to be blunted. We used cafeteria diet fed obese rats as a model to study the central mechanisms involved in growth hormone secretion changes which are observed in obesity. We analysed somatostatin messenger RNA and protein levels in the hypothalamic periventricular nucleus of the rats by non radioactive in situ hybridization and immunocytochemistry respectively. The optical density of somatostatin mRNA, measured by a computerized image system, was significantly higher in cafeteria diet fed rats (1014 +/- 87 vs 444 +/- 45; p < 0.05). The integrated optical density of somatostatin protein was also significantly higher in cafeteria rats compared to the control rats (222 +/- 36 vs 114 +/- 24; p < 0.05). In conclusion, cafeteria diet induced obese rats have a higher somatostatin biosynthesis in the periventricular nucleus. Further studies are needed to establish the possible link of this increased somatostatin gene expression with the decreased GH production.
Assuntos
Dieta/efeitos adversos , Regulação da Expressão Gênica no Desenvolvimento/genética , Hipotálamo/química , Obesidade/metabolismo , Somatostatina/análise , Animais , Modelos Animais de Doenças , Hipotálamo/metabolismo , Imuno-Histoquímica , Hibridização In Situ , Masculino , Obesidade/etiologia , RNA Mensageiro/análise , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Ratos , Ratos Wistar , Somatostatina/biossíntese , Somatostatina/genéticaRESUMO
The pituitary-specific transcription factor Pit-1/GHF-1 is a member of the POU domain family of regulatory proteins. It is involved in the commitment and expansion of the somatotropic cell lineage and activates the transcription of a set of anterior pituitary genes. We have cloned the human PIT1/GHF1 gene and characterized the regulatory mechanisms controlling its promoter activation and regulation. A minimal promoter region (-102 to +15) contains the cis-acting elements that confer to the human PIT1/GHF1 gene a high basal transcriptional activity, the tissue-specific expression, and the autoregulation by Pit-1/GHF-1 protein. The upstream promoter region contains a multiplicity of Pit-1/GHF-1 binding sites that do not show any synergistic interaction with the minimal promoter. The transcriptional activity is negatively regulated by Oct-1 and mediated by an octamer-binding site (OTF). In addition, we have also identified a 12-O-tetradecanoylphorbol-13-acetate-responsive element, which overlaps with a Pit-1/GHF-1 binding site. A mutually exclusive binding of the activator protein-1 (AP-1) and Pit-1/GHF-1 has been observed on this composite site, and AP-1 was shown to down-regulate PIT1/GHF1 transcription.
Assuntos
Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/farmacologia , Regulação para Baixo/efeitos dos fármacos , Proteínas de Homeodomínio/genética , Fator de Transcrição AP-1/farmacologia , Fatores de Transcrição , Fatores de Transcrição/genética , Fatores de Transcrição/farmacologia , Sequência de Bases , Proteínas de Ligação a DNA/metabolismo , Células HeLa , Proteínas de Homeodomínio/metabolismo , Homeostase , Fator C1 de Célula Hospedeira , Humanos , Dados de Sequência Molecular , Fator 1 de Transcrição de Octâmero , Regiões Promotoras Genéticas , Fator de Transcrição Pit-1 , Fatores de Transcrição/metabolismoRESUMO
The expression of the pituitary adenylate cyclase-activating polypeptide/vasoactive intestinal polypeptide (PACAP/VIP) receptor subtypes was evaluated in the normal rat pituitary gland and in different rat spontaneous transplantable SMtTW tumours (SMtTW2 which expresses prolactin (PRL), SMtTW10 which expresses GH and SMtTW3 which expresses both PRL and GH) by measurement of PACAP/VIP-stimulated adenylate cyclase activity and detection of the presence of mRNA coding for the different receptor forms. In normal glands, the order of potency of the peptides suggested that adenylate cyclase activity was mediated through interaction with PACAP selective receptors (PACAP I receptors); mRNAs coding for the PACAP I receptor, but also for the PACAP II VIP2 receptor, were detected. In SMtTW2 tumours, the functional response was close to that observed in the presence of PACAP II VIP2 receptors; mRNAs coding for PACAP I and PACAP II VIP1 and PACAP II VIP2 receptors were detected. In the SMtTW10 tumours, the functional response was complex but compatible with the involvement of PACAP I and PACAP II receptors; mRNAs coding for the PACAP I and PACAP II VIP1 receptors were detected. In the SMtTW3 tumour, the profile was similar to that of the normal pituitary gland and the mRNA coding for the PACAP I receptor only was detected. Thus, while the control of normal pituitary gland adenylate cyclase activity by PACAP and VIP was mediated by PACAP-selective receptors, in spontaneous transplantable tumours a variable profile was observed and PACAP, as well as VIP1 and VIP2 receptors, may contribute to the responses.
Assuntos
Hipófise/metabolismo , Neoplasias Hipofisárias/metabolismo , Receptores do Hormônio Hipofisário/biossíntese , Receptores de Peptídeo Intestinal Vasoativo/biossíntese , Transcrição Gênica , Adenilil Ciclases/metabolismo , Animais , Linhagem Celular , Membrana Celular/metabolismo , Colforsina/farmacologia , Primers do DNA , Guanosina Trifosfato/farmacologia , Guanilil Imidodifosfato/farmacologia , Cinética , Transplante de Neoplasias , Neuropeptídeos/farmacologia , Polipeptídeo Hipofisário Ativador de Adenilato Ciclase , Reação em Cadeia da Polimerase , RNA Mensageiro/análise , RNA Mensageiro/biossíntese , Ratos , Receptores de Polipeptídeo Hipofisário Ativador de Adenilato Ciclase , Receptores do Hormônio Hipofisário/classificação , Receptores de Peptídeo Intestinal Vasoativo/classificação , Receptores Tipo II de Peptídeo Intestinal Vasoativo , Valores de Referência , Fluoreto de Sódio/farmacologiaRESUMO
We have combined different techniques to analyse passages of five different rat spontaneous pituitary tumours (SMtTW) that were transplanted under the kidney capsule. These tumours were secreting prolactin (PRL), GH or both hormones. RIA, immunocytochemistry (ICC) and Western blot analysis were applied to characterize the hormone(s) stored (ICC and Western blot) and secreted (RIA). mRNA content was analysed by PCR, Northern blot analysis and in situ hybridization. The data point not only to the reliability of the techniques used at both protein and RNA levels for each tumour studied but also to the complementarity of some techniques. For example, whereas Northern blot analysis demonstrates the presence and size of hormone mRNA, in situ hybridization indicates the percentage of cells expressing a given hormone mRNA and allows the presence of one population (or more) of cells in a given tumour to be identified. Moreover, the tumours were compared with normal rat pituitary. Although the PRL and GH mRNAs were identical in size, the amount of mRNA was lower in the tumours. At the protein level, the PRL and GH variants exhibited a different pattern of expression in tumours compared with the normal rat pituitary. The biological significance of these differences is discussed.
Assuntos
Hormônio do Crescimento/metabolismo , Proteínas de Neoplasias/metabolismo , Neoplasias Hipofisárias/metabolismo , Prolactina/metabolismo , Animais , Sequência de Bases , Northern Blotting , Western Blotting , Feminino , Regulação Neoplásica da Expressão Gênica , Hormônio do Crescimento/genética , Hibridização In Situ , Dados de Sequência Molecular , Peso Molecular , Transplante de Neoplasias , Adeno-Hipófise/metabolismo , Neoplasias Hipofisárias/genética , Reação em Cadeia da Polimerase , Prolactina/genética , RNA Mensageiro/análise , RNA Neoplásico/análise , Radioimunoensaio , Ratos , Ratos Endogâmicos WF , Ensaio de Cápsula Sub-RenalRESUMO
An alternative splice acceptor site in intron 1 of the human GHF-1/PIT-1 gene was sequenced. The use of this splice site is responsible for a 78-bp in-frame insertion upstream from exon 2 and leads to the hGHF-2/PIT-2 cDNA detected in normal human pituitary.
Assuntos
Processamento Alternativo/genética , Proteínas de Ligação a DNA/genética , Fatores de Transcrição/genética , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , DNA Complementar , Humanos , Íntrons/genética , Dados de Sequência Molecular , Hipófise/metabolismo , Fator de Transcrição Pit-1RESUMO
Adenomas can develop from each cell type of the anterior pituitary. In the normal pituitary, three of these cells types, the GH-, prolactin- and TSH-secreting cells, express the transcription factor Pit-1/GHF-1 which is responsible for prolactin and GH (and probably TSH) cell commitment, differentiation, probably proliferation and gene expression. We have analysed the expression of Pit-1/GHF-1 in a panel of human pituitary adenomas. All GH-, prolactin- and TSH-expressing adenomas studied expressed the Pit-1/GHF-1 factor, as demonstrated by in-situ hybridization and immunocytochemistry. The expression was higher in adenomas than in normal human pituitary. In contrast, ACTH- and LH-FSH-secreting and non-secreting adenomas were negative. Seven transplants of the spontaneous rat prolactinoma SMtTW were also investigated and all were found to be positive. This further stresses the analogy between these tumours and human prolactinomas. Taken together, the data confirm that Pit-1/GHF-1 expression is restricted to GH-, prolactin- and TSH-expressing cells, and the increased expression in adenomas is compatible with a role of Pit-1/GHF-1 in cell proliferation.
Assuntos
Adenoma/genética , Proteínas de Ligação a DNA/genética , Regulação Neoplásica da Expressão Gênica , Proteínas de Neoplasias/genética , Neoplasias Hipofisárias/genética , Fatores de Transcrição/genética , Adenoma/metabolismo , Animais , Proteínas de Ligação a DNA/biossíntese , Feminino , Humanos , Técnicas Imunoenzimáticas , Hibridização In Situ , Proteínas de Neoplasias/biossíntese , Hormônios Adeno-Hipofisários/biossíntese , Hormônios Adeno-Hipofisários/genética , Neoplasias Hipofisárias/metabolismo , Ratos , Ratos Endogâmicos WF , Transdução de Sinais , Especificidade da Espécie , Fator de Transcrição Pit-1 , Fatores de Transcrição/biossínteseRESUMO
The pituitary secretory proteins growth hormone (GH) and prolactin (PRL) do not, as yet, have major roles in haematology or immunology. Recent evidence indicates that these hormones are haemopoietic growth factors and exert immunomodulatory functions at physiological concentrations. Here Robert Hooghe and colleagues discuss the significance of these hormones on different aspects of the immune system.