Preparation of PrP-specific Polyclonal Antibody Immunization of -knockout Mice with Recombinant Human PrP Protein / 生物医学与环境科学（英文）

Objective@#The definite diagnosis of human and animal prion diseases depends on the examination of special pathological changes and/or detection of PrP in the brain tissues of suspected cases. Thus, developing methods to obtain PrP antibody with good specificity and sensitivity is fundamental for prion identification.@*Methods@#We prepared a PrP-specific polyclonal antibody (pAb P54) in a -knockout mouse model immunization with recombinant full-length human PrP protein residues 23-231. Thereafter, we verified that pAb in Western blot, immunohistochemistry (IHC), and immunofluorescent (IFA) assays.@*Results@#Western blot illustrated that the newly prepared pAb P54 could react with recombinant PrP protein, normal brain PrP from healthy rodents and humans, and pathological PrP in the brains of experimental rodents infected with scrapie and humans infected with different types of prion diseases. The electrophoretic patterns of brain PrP and PrP observed after their reaction with pAb P54 were nearly identical to those produced by commercial PrP monoclonal antibodies. Three glycosylated PrP molecules in the brain homogenates were clearly demonstrated in the reactions of these molecules with pAb P54. IHC assay revealed apparent PrP deposits in the GdnCl-treated brain slices of 139A-infected mice and 263K-infected hamsters. IFA tests with pAb P54 also showed clear green signals surrounding blue-stained cell nuclei.@*Conclusion@#The newly prepared pAb P54 demonstrated reliable specificity and sensitivity and, thus, may have potential applications not only in studies of prion biology but also in the diagnosis of human and experimental rodent prion diseases.

Interações proteína príon e seus ligantes STI1 e laminina: possíveis implicações na doença de Alzheimer / Interactions of the prion protein and its ligands STI1 and laminin: possible implications for Alzheimer’s disease

A Doença de Alzheimer (DA) é uma demência progressiva que tem como principais características a disfunção sináptica e a neurodegeneração em áreas específicas do cérebro, que levam a um quadro grave de perda de memória e outras habilidades cognitivas. Uma das principais características neuropatológicas é a deposiçãode placas amiloides extracelulares, que contêm principalmente o peptídeo beta-amiloide (Aβ), que é formado por um processamento alterado da proteína precursora amiloide (APP). Os oligômeros formados por Aβ (AβO) são considerados os elementos tóxicos mais importantes deste processo, esses se ligam às sinapses e estão estreitamente relacionados com a patogênese da DA. Recentemente, foi descrito que a proteína príon celular (PrPC) é um receptor para AβO, porém, os mecanismos envolvidos nesta interação e de que forma esta pode estar relacionada à DA ainda não foram elucidados. PrPC é uma glicoproteína ancorada à membrana plasmática que interage com diversos ligantes, como a proteína de matriz extracelular laminina e a co-chaperona STI1 (Stress Inducible Protein 1). Estas interações induzem neuroproteção, neuritogênese e modulam a formação de memória. Deste modo, torna-se interessante verificar um possível efeito neuroprotetor dos ligantes de PrPC contra a toxicidade produzida pelos AβO. Utilizando culturas neuronais, observamos que os tratamentos com AβO levam uma diminuição nos níveis da proteína sináptica sinaptofisina (Syp), devido a um aumento da degradação..

Alzheimer's disease (AD) is a progressive dementia mainly characterized by synaptic dysfunction and neurodegeneration in specific areas of the brain, leading to severe memory loss, and others cognitive inabilities. One of the main neuropathological characteristics is the formation of extracellular amyloid plaques, which mainly contain beta-amyloid peptide (Aβ). This peptide is formed by an alteration in the processing of the amyloid precursor protein (APP). The Aβ oligomers (AβO) are considered the major toxic components within this process where they bind to synapses and are closely related to the pathogenesis of the AD. Recently, it was reported that PrPC is a receptor for AβO, however, the mechanisms involved in this interaction and how this may be related to AD have not yet been elucidated. The cellular prion protein (PrPC) is a glycoprotein anchored to the plasma membrane that interacts with several ligands such as the co-chaperone STI1 (Stress inducible protein 1) and the extracellular matrix protein laminin. These interactions induce neuroprotection, neuritogenesis, and modulate memory formation. Therefore, it becomes interesting to verify a possible neuroprotective effect of PrPC ligands against the toxicity induced by AβO. We observed that the treatment of neuronal cultures with AβO lead to a decrease in the levels of synaptic protein synaptophysin (Syp) due to an increase of Syp degradation by the proteasome...

O papel da proteína prion celular na regulação da resposta à insulina / The role of cellular prion protein in the regulation of insulin signaling

A proteína Príon Celular ou PrPc, é uma molécula de superfície celular responsável por desencadear várias cascatas de transdução de sinal e mediar muitos processos fisiológicos como proteção contra apoptose, indução da proliferação, adesão celular entre outros. Devido à sua grande gama de efeitos, hoje se acredita que PrPc seja um organizador de plataformas lipídicas, ou lipid rafts, na membrana celular. O receptor de insulina é uma proteína transmembrana também presente em plataformas lipídicas e, interessantemente, a ausência de componentes destas plataformas, como caveolinas, por exemplo, leva a uma deficiência na resposta a insulina. Desta maneira, acreditávamos que a ausência de PrPc poderia levar a uma desregulação das plataformas lipídicas e a uma sinalização ineficiente do receptor de insulina. De fato, pudemos observar a influência de PrPc no controle da glicemia sérica, através de experimentos com camundongos que fizeram ingestão de rações com conteúdo controlado de gordura. Foi possível verificar que camundongos deficientes para PrPc não possuem controle adequado da glicemia, de peso e dos níveis de insulina. Estes resultados foram confirmados em duas cepas diferentes de camundongos deficientes para PrPc. Por outro lado, camundongos que superexpressam PrPc apresentam controle adequado de glicemia por mais tempo que camundongos do tipo-selvagem quando alimentados com dietas de alta porcentagem de gordura, sugerindo que a superexpressão de PrPc promoveria uma resistência ao diabetes tipo II, com maior sensibilidade a insulina. As análises histológicas também mostraram que os animais deficientes para PrPc apresentam esteatose hepática mais acentuada do que os animais do tipo selvagem, assim como hipertrofia dos adipócitos, o que é característico de obesidade. Porém ao longo dos nossos estudos com fibroblastos derivados de camundongos deficientes para PrPc, do tipo selvagem e que superexpressam PrPc, pudemos verificar...

The cellular prion protein or PrPc is a cell surface molecule responsible for triggering various signal transduction cascades and mediate many physiological processes such as protection against apoptosis, inducing proliferation, cell adhesion, among others. Due to its wide range of effects, it is believed that PrPc is a lipid raft organizer in the cell membrane. The insulin receptor is a transmembrane protein also present in lipid rafts. Interestingly, the absence of lipid rafts’s components as caveolins, for example, leads to a deficiency in insulin response. Thus, we believed that the absence of PrPc could lead to a dysregulation of lipid rafts and inefficient insulin receptor signaling. In fact, we observed the influence of PrPc in the control of serum glucose, through experiments with mice that ingested diets with controlled fat content. We found that mice deficient for PrPc do not have adequate control of blood glucose, weight gain and insulin levels. These results were confirmed in two different strains of PrPc knockout mice. On the other hand, mice overexpressing PrPc exhibit adequate control of blood glucose longer than wild-type mice when fed with high fat chow, suggesting that overexpression of PrPc promote resistance to Type II diabetes, with greater insulin sensitivity. The histological analysis also showed that PrPc deficient mice exhibit more pronounced hepatic steatosis than wild-type animals, as well as adipocyte hypertrophy, which is characteristic of obesity. However, throughout our studies with fibroblasts derived from mice deficient for PrPc, wild-type and overexpressing PrPc, we could not prove our initial hypothesis of change in insulin receptor activity. However, we observed that mice deficient for PrPc have lesser amounts of PPAR-y, a transcription factor involved in adipocyte differentiation that has influence on glucose regulation. Additionally, by flow cytometry, we found that the translocation of the glucose transporter Glut4...

O papel da proteína prion celular na regulação da resposta à insulina / The role of cellular prion protein in the regulation of insulin signaling

A proteína Príon Celular ou PrPc, é uma molécula de superfície celular responsável por desencadear várias cascatas de transdução de sinal emediar muitos processos fisiológicos como proteção contra apoptose,indução da proliferação, adesão celular entre outros. Devido à sua grandegama de efeitos, hoje se acredita que PrPc seja um organizador de plataformas lipídicas, ou lipid rafts, na membrana celular. O receptor deinsulina é uma proteína transmembrana também presente em plataformaslipídicas e, interessantemente, a ausência de componentes destasplataformas, como caveolinas, por exemplo, leva a uma deficiência naresposta a insulina. Desta maneira, acreditávamos que a ausência de PrPcpoderia levar a uma desregulação das plataformas lipídicas e a umasinalização ineficiente do receptor de insulina. De fato, pudemos observar ainfluência de PrPc no controle da glicemia sérica, através de experimentos com camundongos que fizeram ingestão de rações com conteúdo controlado de gordura. Foi possível verificar que camundongos deficientes para PrPc não possuem controle adequado da glicemia, de peso e dos níveis de insulina. Estes resultados foram confirmados em duas cepas diferentes de camundongos deficientes para PrPc. Por outro lado, camundongos que superexpressam PrPc apresentam controle adequado de glicemia por mais tempo que camundongos do tipo-selvagem quando alimentados com dietas de alta porcentagem de gordura, sugerindo que a superexpressão de PrPc promoveria uma resistência ao diabetes tipo II, com maior sensibilidade a insulina. As análises histológicas também mostraram que os animaisdeficientes para PrPc apresentam esteatose hepática mais acentuada doque os animais do tipo selvagem, assim como hipertrofia dos adipócitos...

The cellular prion protein or PrPc is a cell surface molecule responsible fortriggering various signal transduction cascades and mediate manyphysiological processes such as protection against apoptosis, inducingproliferation, cell adhesion, among others. Due to its wide range of effects, itis believed that PrPc is a lipid raft organizer in the cell membrane. The insulinreceptor is a transmembrane protein also present in lipid rafts. Interestingly,the absence of lipid rafts’s components as caveolins, for example, leads to adeficiency in insulin response. Thus, we believed that the absence of PrPccould lead to a dysregulation of lipid rafts and inefficient insulin receptorsignaling. In fact, we observed the influence of PrPc in the control of serumglucose, through experiments with mice that ingested diets with controlled fatcontent. We found that mice deficient for PrPc do not have adequate controlof blood glucose, weight gain and insulin levels. These results wereconfirmed in two different strains of PrPc knockout mice. On the other hand,mice overexpressing PrPc exhibit adequate control of blood glucose longerthan wild-type mice when fed with high fat chow, suggesting thatoverexpression of PrPc promote resistance to Type II diabetes, with greaterinsulin sensitivity. The histological analysis also showed that PrPc deficientmice exhibit more pronounced hepatic steatosis than wild-type animals, aswell as adipocyte hypertrophy, which is characteristic of obesity. However,throughout our studies with fibroblasts derived from mice deficient for PrPc,wild-type and overexpressing PrPc, we could not prove our initial hypothesisof change in insulin receptor activity. However, we observed that micedeficient for PrPc have lesser amounts of PPAR-y, a transcription factorinvolved in adipocyte differentiation that has influence on glucose regulation

Study on the correlation between membrane protein Flotillin-1 and PrPc endocytosis / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To explore whether the membrane-associated protein Flotillin-1 has relationship with endocytosis of PrPc.</p><p><b>METHODS</b>The expression of Flotillin-1 in different cell lines was detected with the method of Western Blot; the interaction between Flotillin-1 and PrPc in Cells which were treated with copper ions was observed using immunoprecipitation method.</p><p><b>RESULTS</b>(1) Flotillin-1 was widely expressed in many cell lines without significant difference in the amounts of expression level; (2) Only in the appearance of copper ions, the protein complexes of PrPc and Flotillin-1 can be detected with the method of IP, which were related to copper ions concentration and processing time.</p><p><b>CONCLUSION</b>The membrane-associated protein Flotillin-1 has the relationship with the endocytosis of PrPc.</p>

Avaliação da expressão de PrPc na interação neurônio-glia, em astrócitos e os mecanismos de secreção de STI1 / Avaliation of PrPc expression in neuron-glia crosstalk, in astrocytes and the mechanisms of STI1 secretion

As funções fisiológicas da proteína prion (PrPc) estão sob ampla investigação e caracterização, especialmente as funções associadas ao desenvolvimento cerebral. Destaca-se que a associação de PrPc com Stress Inducible Protein 1 (STI1), induz neuritogênese e neuroproteção via proteína cinase extracelular reguladora (ERK) e proteína cinase dependente de AMPc (PKA) respectivamente. O presente estudo avaliou como a expressão de PrP cem astrócitos pode modular a interação neurônioglia e o papel de STI1 como um fator autócrino em astrócitos. PrPc modula a interação neurônio-glia, a produção de fatores tróficos solúveis e a organização da laminina secretada na matriz extracelular pelos astrócitos. Desta forma, a expressão de PrP ctanto em astrócitos quanto em neurônios é essencial para a neuritogênese e sobrevivência neuronal. O papel autócrino de STI1 em astrócitos também foi demonstrado. A interação PrPc-STI1 previne a morte celular por ativação da via de PKA, e ativa a diferenciação astrocitária, de uma forma protoplasmática para uma fibrosa pela indução de ERK1/2. De acordo com estes resultados, um menor grau de diferenciação é encontrado em camundongos deficientes para PrPc...

The physiological functions of PrPc are under intense investigation and characterization, particularly those associated with brain development. In neurons, the association of PrPc with its ligand, STI1, induces neuritogenesis and neuroprotection via ERK and PKA signaling pathways, respectively. The present study evaluated whether PrPc expression in astrocytes modulates neuron-glia crosstalk and the autocrine role of STI1 in astrocytes. PrPc modulates neuron-glia interaction, the production and secretion of soluble factors, and the organization of the laminin in the extracellular matrix. PrPc expression in neurons and astrocytes is essential to neuritogenesis and neuronal survival. The autocrine role of STI1 in astrocytes was also demonstrated. The PrPc-STI1 interaction prevents cell death in a PKA-dependent manner, and induces astrocyte differentiation, from a flat to a process-bearing morphology in an ERK1/2 dependent manner. We showed that PrPccnull astrocytes presented a slower rate of astrocyte maturation than wild-type ones, with reduced expression of GFAP and increased vimentin and nestin expression...

Stable inhibition of human prion protein through a retrovirus-based RNAi system / 生物工程学报

Prion leads to fatal transmissible spongiform encephalopathies. Cellular prion protein (PrPc) is necessary in prion disease. At present, it is demonstrated that PrPc plays a protective role in several carcinomas, such as gastric and breast cancer. We designed four 19-nt siRNAs according to cDNA sequence of human PrPc and constructed retrovirus-based RNAi vectors. We evaluated the inhibitive effect of these sequences on HuPrPc (human PrPc) and selected out three sequences with stable and efficient inhibition. And the efficiency of si626 reached more than 85%, which effect was significant. Next, we performed cell invasion assays of PC3M-si292 and PC3M-si626 in which PrPc was inhibited. And it showed that the cell invasive ability decreased in PrPc knock-down cell lines. This will make preparations for the further research on gene therapy of prion diseases and PrPc related carcinoma treatment and PrPc could be considered as a potential therapeutic target molecule in prostate cancer treatment.

Establishment of PrP(Sc) conversion based on serial PMCA in vitro / 病毒学报

In order to establish an amplification system in vitro with which the PrP(Sc) is able to convert PrP(C) into proteinase K-resistant isoform infinitely and whether this system is more efficient than conventional protein misfolding cyclic amplification (PMCA), scrapie strain 263K-infected hamster's brain homogenate and homologous normal brain homogenate were prepared, respectively. A new methodology, namely serial PMCA, was utilized to reveal the continuous propagation ability of PrP(Sc). Totally 8 rounds of serial PMCA were proceeded and each round contained 48 cycles of alternative sonication and incubation. Simultaneously 144 cycles of conventional PMCA was used as a control. The results showed the PrP(Sc) from hamsters' brain tissues of scrapie agent 263K could replicate efficiently and infinitely with serial PMCA compared with finite propagation of PrP(Sc) with conventional PMCA system. The study of PrP(Sc) continuous propagation in brain homogenate with serial PMCA may further provide insight into the unsettled mechanism of prions misfolding and replication and apply to detect trace amount of PrP(Sc).

Establishment of a prion disease PrP(Sc) panel from the brain tissues of experimental hamsters infected with scrapie agent 263K / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To establish a prion disease PrP(Sc) panel from the brain tissues of experimental hamsters and to address the stability of the panel conserved under the specific condition, for evaluating the diagnostic techniques of human and animal's prion diseases.</p><p><b>METHODS</b>30 brain tissues of hamsters infected with scrapie strain 263K intracerebrally and 30 ones of normal hamsters were enrolled in this panel. Each brain sample was prepared to 10%, 1% and 0.5% homogenates and aliquoted into stocks. The presences of PrP(Sc) in each brain sample were evaluated with PrP-specific Western Blots and partially with immunohistochemistry, and the stability of PrP(Sc) signals in each sample were repeatedly assessed half a year later and 3 years later.</p><p><b>RESULTS</b>PrP(Sc) signals were detected in all stocks of 10% brain homogenates from infected hamsters, 26 out of 30 stocks of 1% homogenates and 19 out of 30 stocks of 0.5% homogenates. The assessments of PrP(Sc) signals in all samples half-year and three years later demonstrated almost unchanged. All homogenates of brain tissues of normal hamsters were PrP(Sc) negative.</p><p><b>CONCLUSION</b>A prion disease PrP(Sc) panel of the brain tissues, which includes 90 PrP(Sc) positive stocks and PrP(Sc) negative ones, was successfully established, with a reliable stability of PrP(Sc) signals.</p>

Forma familiar de la enfermedad de Creutzfeldt-Jakob: marcadores genéticos en 4 familias chilenas / Genetic markers in four Chilean families with familial Creutzfeldt-Jakob disease

Background: Creutzfeldt-Jakob disease (CJD) is a form of transmissible spongiform encephalopathy, in which a prion protein (PrP Sc) accumulates in the brain of affected individuals. Chile has a prevalence of CJD that is more than twice than in the rest of the world and has the highest rate of familial forms. These later forms are associated with the heterozygocity of codon 200 of PrP protein gene. Aim: To search susceptibility genetic markers of CJD in members of families affected by CJD. Material and methods: A blood sample was obtained from 50 individuals pertaining to four families affected by CJD. DNA from peripheral mononuclear cells was amplified by polymerase chain reaction and sequenced for the gene that codifies PrP protein. Results: In family A, 21 of 23 members were homozygotes for codon 129 (Met/Met) and eight were simultaneously heterozygotes for codon 200 (Glu/Lys). In family B, six of nine members were homozygotes for codon 129, five were heterozygotes for codon 200 and four had both mutations. In family C, the four analyzed subjects were homozygotes for codon 129 and two were simultaneously heterozygotes for codon 200. In family D, nine of 14 members were homozygotes for codon 129 and two were simultaneously homozygotes for codon 200. No family had polymorphisms for codon 219. Conclusions: Thirty two percent of analyzed subjects were homozygotes for codon 129 and heterozygotes for codon 200, condition that defines the genetic susceptibility to acquire CJD. The dominant tendency of these genotypes could explain the higher incidence of CJF in Chile.

The functional links between prion protein and copper

Prion diseases are fatal neurodegenerative disorders associated with the conversion of the cellular prion protein (PrPC) into a pathologic isoform. Although the physiological function of PrPC remains unknown, evidence relates PrPC to copper metabolism and oxidative stress as suggested by its copper-binding properties in the N-terminal octapeptide repeat region. This region also reduces copper ions in vitro, and this reduction ability is associated with the neuroprotection exerted by the octarepeat region against copper in vivo. In addition, the promoter region of the PrPC gene contains putative metal response elements suggesting it may be regulated by heavy metals. Here we address some of the evidence that support a physiological link between PrPC and copper. Also, in vivo experiments suggesting the physiological relevance of PrPC interaction with heparan sulfate proteoglycans are discussed.

Preparation of monoclonal antibodies against prion proteins with full-length hamster PrP / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To prepare the PrP specific monoclonal antibodies (mAbs) that can be used for the detection of mammalian prions and study of pathogenesis of prion diseases.</p><p><b>METHODS</b>Several BALB/c mice were immunized with recombinant hamster prion protein (HaPrP). Three hybridoma cell lines designated as B7, B9, and B10, secreting monoclonal antibodies against HaPrP, were established by hybridoma technique. The mAbs reactivities were evaluated with ELISA, Western blot, and immunohistochemistry.</p><p><b>RESULTS</b>The mAbs produced by these cell lines reacted well with different recombinant hamster PrP proteins. Western blot analyses showed that mAbs B7 and B9 reacted with PrPSc from the scrapie-infected animals after proteinase K digestion with three glycosylated forms. The mAbs exhibited cross-reactivity with various PrPC from several other mammalian species, including humans and cattles. Immunohistochemistry assays confirmed that mAbs B7 and B9 could recognize not only extracellular but also intracellular PrPsSc.</p><p><b>CONCLUSION</b>The mAbs of prion protein are successfully generated by hybridoma technique and can be applied for the diagnosis of prion associated diseases.</p>

Doença de Creutzfeldt-Jakob forma Heidenhain: relato de caso com achados de ressonância magnética e DWI / Creutzfeldt-Jakob disease, Heidenhain variant: case report with MRI (DWI) findings

A doença de Creutzfeldt-Jakob (CJD) é uma forma de demência pré-senil de rápida evolução, geralmente fatal em um ano. Casos autóctones no Brasil têm sido raramente descritos assim como achados de ressonância magnética. Mulher, natural de Ponta Grossa PR, branca , 54 anos , foi admitida no serviço em outubro de 2001 com quadro de amaurose bilateral cortical progressiva desde há 1 mês do internamento. Nunca viajou ao exterior e foi somente submetida a uma cirurgia de redução do estômago, para obesidade. História familial sem relato de casos semelhantes. Logo após o internamento a paciente desenvolveu quadro de disfasia mista, hemiparesia flácida direita, com movimentos coreoatetóticos e crises parciais motoras. Paciente evoluiu com quadro demencial progressivo; atualmente, acamada, torporosa, dependente de alimentação enteral, recebendo mepacrina, fenitoína e clorpromazina , estabilizando o quadro até final de maio de 2002. Exames laboratoriais negativos ou normais. Pesquisa de proteína 14-3-3 no líquor foi positiva; enolase-neurônio-específica no líquor foi normal. Estudo genético do gen PRNP não revelou mutação descrita anteriormente. EEG (23/10/2001) revelou intensa atividade irritativa hemisfério cerebral esquerdo. Estudo de ressonância magnética revelou áreas de hipersinal em T2 e FLAIR em regiões temporal esquerda e bioccipital; gânglios da base normal. Imagens de DWI mostraram hipersinal nas mesmas áreas.Outro EEG (15/03/2002) revelou padrão periódico de ondas trifásicas sugestivos de CJD. A paciente fez uso de mepacrina associado a clorpromazina com aparente estabilização do quadro, até seu óbito por complicações infecciosas pulmonares em abril de 2003.

Dynamic analyses of PrP and PrP(Sc) in brain tissues of golden hamsters infected with scrapie strain 263K revealed various PrP forms / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To expatiate dynamic changes in hamsters infected with scrapie strain 263K, to observe the presence and aggravation of various forms of PrP and PrP(Sc) during incubation period, and to probe primarily the relationship between the onset of clinic manifestations and the presence of different PrP(Sc) forms.</p><p><b>METHODS</b>Hamster-adapted scrapie strain 263K was intracerebrally inoculated into hamsters. Different forms of PrP and PrP(Sc) were monitored dynamically by Western blot and immuno-histochemical assays. The presence of scrapie-associated fibril (SAF) was assayed by electron microscopy analysis (EM) and immuno-golden EM.</p><p><b>RESULTS</b>PrP(Sc) was initially detected in the brain tissues of the animals in 20 days post-inoculation by immunohistochemistry and 40 days with Western blot. Quantitative evaluations revealed that the amounts of PrP and PrP(Sc) in brain tissues increased along with the incubation. Several high and low molecular masses of PrP were seen in the brains of the long-life span infected animals. Deglycosylation assays identified that the truncated PrP in the infected brains showed similar glycosylation patterns as the full-length PrP. The presence of short fragments was seemed to relate with the onset of clinical conditions.</p><p><b>CONCLUSION</b>These results indicate that infectious agents exist and accumulate in central nerve system prior to the onset of the illness. Various molecular patterns of PrP(Sc) may indwell in brain tissues during the infection.</p>

Interaçäo da proteína prion celular com laminina e STI-1 e suas possíveis implicações biológicas / Cellular prion protein interaction with laminin and STI-1 and its possible biological implications

A conversäo da proteína príon celular (PrPc) em sua isoforma anormal PrPsc está associada a uma série de doenças neurodegenerativas, genericamente designadas por doenças priônicas. Embora a literatura tenha enfatizado o estudo do PrPsc e o mecanismo de propagaçäo das doenças de príon, pouco tem sido feito para o entendimento do papel fisiológico do PrPc. Em 1997 nosso grupo descreveu um receptor/ligante para o PrPc utilizando o princípio da hidropaticidade complementar. Neste trabalho isolamos e identificamos este ligante de PrPc como sendo a STI-1 (Stress Inducible Protein-1). In vitro, a STI-1 interage com o PrPc de maneira específica, saturável e com alta afinidade (Kd=8x10-8M)...

Caracterização das vias de sinalização desencadeadas pelas interações PrPc-p66 e PrPc-Laminina e sua relevância nos processos de morte celular programada e consolidação da memória / Characterization of the signalling pathways triggered by interactions, PrPc-p66 and PrPc-laminin and their relevance in programmed cell death process and memory consolidation

PrPc é uma glicoproteína de 35 KDa, bastante conservada entre as espécies e essencial no processo de transmissão e patogênese de várias doenças neurodegenerativas como a encefalopatia espongiforme bovina e a doença de Creutzfedt-Jacob (PRUSINER, 1991). Embora sua função fisiológica ainda seja desconhecida, sabe-se que a patogênese das doenças priônicas requer a sua expressão e é freqüentemente acompanhada do acúmulo no cérebro de uma isoforma anormal de PrPc, designada PrPsc (GABIZON e cols, 1997). Interessado nos possíveis papéis fisiológicos da proteína PrPc, nosso grupo tem se dedicado a estudar as interações que PrPc realiza com outras moléculas...

Biologia da proteína prion celular / Cellular prion protein biology

O prion celular (PrPc) é uma glicoproteína ligada à membrana plasmática por uma âncora de GPI (glycosylphosphatidylinositol). A sua isoforma anormal (PrPsc) é uma molécula infecciosa que causa várias doenças neurodegenerativas em mamíferos. A etiologia dessas doenças está associada a uma mudança conformacional pós-traducional de PrPc que ocorre após sua internalização (Prusiner), 1998. Na tentativa de desvendar as funções fisiológicas de PrPc, nosso grupo tem identificado e caracterizado as interações celulares que PrPc participa. A primeira delas é a interação entre PrPc e STI1 (Stress Inducible Protein 1). Essa interação transduz sinalização por cAMP e PKA levando a neuroproteção contra morte celular programada(Chiarini e cols.2002; Zanata e cols, 2002)

Insights into the physiological function of cellular prion protein

Prions have been extensively studied since they represent a new class of infectious agents in which a protein, PrPsc (prion scrapie), appears to be the sole component of the infectious particle. They are responsible for transmissible spongiform encephalopathies, which affect both humans and animals. The mechanism of disease propagation is well understood and involves the interaction of PrPsc with its cellular isoform (PrPc) and subsequently abnormal structural conversion of the latter. PrPc is a glycoprotein anchored on the cell surface by a glycosylphosphatidylinositol moiety and expressed in most cell types but mainly in neurons. Prion diseases have been associated with the accumulation of the abnormally folded protein and its neurotoxic effects; however, it is not known if PrPc loss of function is an important component. New efforts are addressing this question and trying to characterize the physiological function of PrPc. At least four different mouse strains in which the PrP gene was ablated were generated and the results regarding their phenotype are controversial. Localization of PrPc on the cell membrane makes it a potential candidate for a ligand uptake, cell adhesion and recognition molecule or a membrane signaling molecule. Recent data have shown a potential role for PrPc in the metabolism of copper and moreover that this metal stimulates PrPc endocytosis. Our group has recently demonstrated that PrPc is a high affinity laminin ligand and that this interaction mediates neuronal cell adhesion and neurite extension and maintenance. Moreover, PrPc-caveolin-1 dependent coupling seems to trigger the tyrosine kinase Fyn activation. These data provide the first evidence for PrPc involvement in signal transduction

Estudo da regulação da expressão do gene da proteína prion celular / PrPc protein gene expression regulation study

A conversão da proteína prion celular normal(PrPc), cuja função ainda está sob investigação, para a forma infecciosa (PrPsc) é a causa de algumas doenças neurodegenerativas em humanos e animais. Vários estudos têm sido realizados e mostram que PrPc pode participar de processos normais como memória, estresse oxidativo, neuritogênese e outros. Portanto, a elucidação dos processos de regulação de sua expressão é importante tanto para definir um estratégia para controlar a infeccção quanto para entender melhor a função fisiológica de PrPc. Este trabalho tem objetivo avaliar a expressão de gene de PrPc, a partir da regulação da atividade de seu promotor frente a drogas que foram eleitas de acordo com a composição dos elementos...