RESUMO
Human pregnancy-specific glycoproteins (PSG) are major placental polypeptides encoded by eleven highly conserved genes expressed by the syncytiotrophoblast. The minimal promoter region of all PSG genes contains a putative Retinoic Acid Responsive Element (RARE) though the ability of retinoids to regulate PSG gene expression has not been established. Retinoid signaling pathway plays a key role for overall placenta biology and is essential for trophoblast differentiation. In this work, we investigated the participation of the RARE motif in the regulation of PSG5 gene transcription by retinoic acid and its receptors. The minimal promoter region of PSG5 gene was activated by RXRalpha but not by RARalpha, in a ligand-dependent manner. The RARE sequence of PSG5 gene promoter was recognized by endogenous RXRalpha present in placental nuclear extracts as well as by RXRalpha either over expressed in cultured non-placental cells or in vitro translated. Mutations at specific nucleotides within the RARE motif abrogated both RXRalpha DNA binding and transcriptional activation of PSG5 promoter mediated by RXRalpha. Moreover, endogenous PSG expression was significantly induced in trophoblast-derived Jeg-3 cells upon 9-cis retinoic acid treatment. Interestingly, the induction level was higher following methotrexate-induced differentiation of Jeg-3 cells to syncytiotrophoblast-like structures. Altogether, these data provide the first evidences demonstrating that transcriptional activity of PSG5 gene is responsive to an external signal involving the retinoids-RXRalpha axis through a conserved RARE motif shared by all PSG gene family members.
Assuntos
Linhagem Celular Tumoral , Tretinoína , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Glicoproteínas/metabolismo , Humanos , Gravidez , Regiões Promotoras Genéticas , Fatores de Transcrição/metabolismo , Transcrição Gênica , Ativação TranscricionalRESUMO
The human core promoter binding protein (hCPBP) has been identified as a DNA-binding protein involved in the regulation of TATA box-less genes like those encoding the pregnancy-specific glycoproteins. Structurally, hCPBP contains three zinc fingers in the C-terminal domain, which is highly conserved in a number of proteins that constitute the Krüppel-like family of transcription factors. In the present work, we report the molecular cloning of the mouse CPBP (mCPBP) and its expression pattern during development as well as in adult tissues. The mouse cDNA encodes a protein of 283 amino acids that share 94.4% of identity with the hCPBP. The highest level of mCPBP transcript was detected in placenta, and its expression was lower in total embryos and in adult tissues. We also show by in situ hybridization that during embryonic development the mCPBP gene is mainly expressed in extra-embryonic structures throughout gestation; essentially no specific expression was detected in embryonic tissues. Our data demonstrate that CPBP transcript is enriched in the trophoblastic tissue and strongly suggest that its encoded polypeptide regulates target genes involved in placental development and pregnancy maintenance.
Assuntos
Desenvolvimento Embrionário e Fetal , Expressão Gênica , Placenta/metabolismo , Proteínas Proto-Oncogênicas , Transativadores/genética , Sequência de Aminoácidos , Animais , Clonagem Molecular , Sequência Conservada , Feminino , Humanos , Hibridização In Situ , Fator 6 Semelhante a Kruppel , Fatores de Transcrição Kruppel-Like , Camundongos , Dados de Sequência Molecular , Placenta/química , Gravidez , RNA Mensageiro/análise , Transativadores/química , Dedos de ZincoRESUMO
A comprehensive biochemical, immunological and histological study was undertaken during different stages of experimental allergic encephalomyelitis (EAE). Wistar rats with EAE induced by sensitization with bovine myelin showed a maximum decrease of body weight 14-16 days post-inoculation (dpi), coincident with the appearance of the paralysis symptom (acute period). Quantitation of some brain components indicated a temporal dissociation among the alterations observed. The higher diminution of myelin basic protein (MBP) occurred at 6 dpi and then increased to reach 21 dpi, a normal value. Also, the activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase was reduced by 40% with respect to control animals only at 6 dpi. The total lipid content was normal; however, among the individual lipids, sulfatides were principally degraded during the acute stage but the amount of cerebrosides was decreased during the recovery period (29-40 dpi). Free cholesterol was similar in both groups of animals, whereas cholesterol esters were detected in EAE animals from 14 to 40 dpi. Central nervous system meningeal and parenchymal infiltration with mononuclear cells was recognized principally at 14 dpi, but some of cells were still present at 40 dpi. Deposits of immunoglobulins in the infiltrated regions as well as in spinal cord motor neurons were observed among 14-29 dpi. Total circulating antibodies to MBP began to increase at 14 dpi, reaching a plateau at 21 dpi and then maintaining this value until 40 dpi. However, the population of anti-MBP antibodies that also recognizes the neuronal protein synapsin was only present at 14 dpi. The present results suggest that the neurological symptoms can be related to some early changes in the myelin membrane followed by alterations involving neuronal structures. The existence of immunological factors against some epitopes in MBP that also recognize a synaptosomal protein might account, at least in part, for the axonal damage and disruption of the normal interneuronal activity in EAE and lead together with the alterations in some specific myelin constituents and the concomitant CNS inflammatory process to the observed hindlimb paralysis.