Reproduction de : Thèse d'exercice : Médecine : Nancy 1 : 2003. / Titre provenant de l'écran-titre.

Thesis (Ph. D.)--University of Chicago, Department of Biochemistry and Molecular Biology, 2001. / Includes bibliographical references. Also available on the Internet.

Prion diseases are fatal and incurable neurodegenerative diseases that share many pathological similarities to other neurodegenerative diseases such as Alzheimer’s or Parkinson’s disease. One of the earliest pathological signs commonly detected in all of these diseases is the dysfunction followed by loss of neuronal synapses, spines and eventually dendrites that collectively contribute to disruption of normal brain function. These pathologies tend to progressively accumulate within the brain tissue such that extensive damage typically precedes clinical symptom manifestation and ultimate death of neurons. Clearly, understanding the molecular processes responsible for these pathologies could uncover critical pathway(s) that are responsible for propagating this brain damage and could therefore be exploited for therapy development. However, molecular mechanisms implicated in this early pathology remain unidentified. To address this gap in knowledge, this thesis describes a transcriptional approach coupled with specific isolation of neuronal-enriched tissue which was used to help delineate cellular pathways involved in prion-induced neurodegeneration. Profiling cell bodies of CA1 hippocampal neurons known to be affected during early prion disease revealed temporal alteration in both gene and microRNA (gene regulators) expression throughout disease. On a gene expression level, changes in transcript expression during preclinical disease were reminiscent of an activity-dependent neuroprotective gene signature previously described in the literature. These neuroprotective genes were induced during preclinical disease, diminished as disease progressed and were abolished at clinical disease. In support of this process, upregulation of the phosphorylated form of the neuroprotective transcription factor CREB was detected during preclinical disease in these neurons. Furthermore, several genes known to be induced by CREB were also upregulated at preclinical disease in prion-infected mice. Interestingly, expression of numerous deregulated microRNAs paralleled the neuroprotective gene signature of which several are known to remodel neuronal spines and dendrites. To determine whether other preclinically induced microRNAs were also capable of remodeling neuronal structures, gain-of-function studies were performed in primary mouse hippocampal neurons for the uncharacterized miR-26a-5p. Neurons over-expressing miR-26a-5p had enhanced spine density and dendrite arborization, similar to other preclinically-induced microRNAs. Together, these data suggests that CA1 hippocampal neurons induce a neuroprotective transcriptional signature that is evident early in the course of disease within CA1 hippocampal neurons and is abolished by clinical disease. Reestablishment of key molecules that can induce this neuroprotective signature at a time when these genes begin to dissipate could prolong prion disease onset and delay clinical symptom manifestation. / October 2015

Yeast prions e.g. [PSI+], [PIN+] and [URE3] are similar to mammalian amyloids that cause neurodegenerative diseases. [PSI+] is the aggregated self-perpetuating (prion) isoform of Sup35, a translation termination factor. The molecular chaperone Hsp104 plays a crucial role in the maintenance and propagation of [PSI+]. Deletion of the GET2 gene has been shown to cause a [PSI+] curing defect by excess Hsp104 and [PSI+] instability on synthetic medium (S. Muller, J. Patterson and Y. Chernoff, unpublished data; and J. Patterson Honors Thesis). Get2 is a membrane protein working in a complex with Get1 and Get3 proteins. This complex, called GET (Golgi-to-ER Traffic), is known to retrieve resident ER proteins from Golgi. In this particular study we provide further evidence for the connection between the GET pathway and yeast prions. The get2 deletion also leads to a detectable loss of [PIN+] prion on synthetic medium. The role of the other two members of the Get complex in prion propagation is also explored. The levels and the activity of Hsp104 in the get2 mutants is analyzed. The size of [PSI+] aggregates in the get2Δ strain is compared to that found in wild type. Finally, other possible mechanisms for the effect of get2 on prion maintenance and propagation are addressed.

Prions are self-perpetuating and, in most cases, aggregation-prone protein isoforms that transmit neurodegenerative diseases in mammals and control heritable traits in yeast. Prion conversion requires a very high level of identity of the interacting protein sequences. Decreased transmission of the prion state between divergent proteins is termed "species barrier" and was thought to occur due to the inability of divergent prion proteins to co-aggregate. Species barrier can be overcome in cross-species infections, for example from "mad cows" to humans. We studied the counterparts of yeast prion protein Sup35, originated from three different species of the Saccharomyces sensu stricto group and exhibiting the range of prion domain divergence that overlaps with the range of divergence observed among distant mammalian species. Heterologous Sup35 proteins co-aggregated in S. cerevisiae cells. However, in vivo cross-species prion conversion was decreased and in vitro polymerization was cross-inhibited in at least some heterologous combinations, thus demonstrating the existence of prion species barrier. Our data suggests that species-specificity of prion transmission is controlled at the level of conformational transition rather than co-aggregation. We have shown the Sup35 prion domain is sufficient for the species barrier among the S. sensu stricto species, and constructed SUP35 chimeric prion domains, combining the subregions of various origins Our data demonstrated in different cross-species combinations, different modules of prion domain play a crucial role in the controlling of species-specificity of prion transmission. One essential amino acid position has been identified in S. cerevisiae and S. paradoxus system. Our data support a model suggesting that identity of the short amyloidogenic sequences is crucial for the species barrier. Sup35 originated from three different species of the S. sensu stricto group were capable of forming a prion in S. cerevisiae. However, it was not known whether they are capable of generating and maintaining the prion state in the homologous cell environment. We have constructed the S. paradoxus and S. bayanus strains with appropriate markers, and we were able to demonstrate de novo [PSI+] formation in S. paradoxus but not in S. bayanus. Our data show that [PSI+] formation is not a unique property of S. cerevisiae.

Las enfermedades priónicas, también conocidas como EETs (Encefalopatías Espongiformes Transmisibles), son un grupo de enfermedades neurodegenerativas fatales que, debido a su transmisibilidad potencial han tenido un gran impacto social, político y económico en las últimas décadas. Las EETs afectan a los humanos y a algunos grupos de animales, presentan largos períodos de incubación y producen la muerte pocos meses después de la aparición de la sintomatología clínica. Su origen se atribuye a la presencia, multiplicación y deposición de una proteína anormal llamada prión. El prión (o PrPSc) es una forma mal conformada de la proteína priónica celular (PrPc), presente en condiciones fisiológicas en las membranas de las células. El prión es parcialmente resistente a las proteasas, resistente a desinfectantes físico-químicos convencionales, y capaz de convertir de forma auto-catalítica a la PrPc dando lugar a la propagación en cadena de la forma patogénica. El prión es transmisible, no sólo entre individuos de una misma especie sino también entre individuos de especies diferentes. Las EETs animales más importantes son el scrapie, que afecta a las ovejas y las cabras, y la encefalopatía espongiforme bovina (EEB), que afecta a las vacas (vulgarmente conocida como "mal de las vacas locas").En el caso de las EETs humanas, las más relevantes son la enfermedad de Creutzfeldt-Jakob (ECJ), el síndrome de Gerstmann-Sträussler-Scheinker (GSS), el insomnio familiar fatal (FFI) y el Kuru. La ECJ tiene una incidencia de 1 o 2 casos por millón de habitantes y año en todo el mundo, afecta por igual a hombres y mujeres, y cursa con demencia, mioclonías y ataxia cerebelar. Neuropatológicamente, provoca pérdida neuronal, astrocitosis, microgliosis y cambio espongiforme. La presencia de la proteína 14-3-3 en el LCR y de un EEG típico, son factores diagnóstico, aunque el diagnóstico definitivo se hace a nivel post-mortem con la detección de la PrPSc por inmunohistoquímica y/o western blot.El impacto social y sobre la salud pública y animal que han tenido las enfermedades priónicas en las últimas décadas fue originado, en gran medida, por la epidemia de EEB que afectó en los años 90 al Reino Unido, principalmente. Esta epidemia se atribuyó a la alimentación de las vacas con piensos enriquecidos con proteínas procedentes de ovejas infectadas con scrapie. Debido a la transmisibilidad ínter-específica de los priones, éstos infectaron a las vacas y éstas, al pasar a la cadena alimenticia, a los humanos, dando lugar a la nueva variante de la ECJ. La ECJ tiene un origen esporádico en un 85% de los casos, es decir, el inicio de la enfermedad se produce de manera espontánea, a pesar de que éste se asocia a la presencia de priones residuales en el SNC, a la generación de mutaciones puntuales en el gen de la PrP (PRNP) o bien a la conversión espontánea de la PrP debido a alteraciones físico-químicas de la proteína. En el 10% de los casos, la ECJ es genética y hereditaria, es decir, se atribuye a mutaciones en el PRNP que pasan a las células germinales y a la nueva generación. En este escenario, se habla de ECJ familiar. El 5% de los casos de ECJ restantes se asocian a una transmisión iatrogénica, es decir, por contaminación durante transplantes, tratamientos hormonales, manipulación quirúrgica, etc., aunque este tipo de transmisión está prácticamente erradicada. El propósito general de esta tesis es el estudio de las EETs dirigido a incrementar el conocimiento acerca de los mecanismos celulares y moleculares implicados en la neuropatología de estas enfermedades. Si bien la multiplicación y deposición del prión se consideran los detonantes de la neuropatología y sintomatología clínica asociadas a las EETs, es asumible que los mecanismos involucrados en estas alteraciones sean complejos y tengan un origen multifactorial. En este escenario, las alteraciones en la neurotransmisión y la disfunción de algunos grupos de proteínas relacionados con la supervivencia celular se consideran cruciales en el desarrollo de las enfermedades priónicas y de sus fenómenos neuropatológicos asociados. Atendiendo a las observaciones anteriores, esta tesis se ha enfocado a estudiar el papel que juegan ciertos grupos de proteínas en la neurotransmisión, la espongiosis y la muerte neuronal. Para abordar experimentalmente cada una de estas líneas de interés, nuestros estudios van ecaminados a: conocer el estado de la vía de señalización vinculada a la transmisión glutamatérgica y de adenosina; conocer el papel de los canales de agua o aquaporinas cerebrales en relación a la vacuolización y al cambio espongiforme característico de las EETs y, por último, estudiar la vía de señalización de las MAPKs en relación a la degeneración neuronal. Estos estudios se realizan sobre corteza frontal de material humano post-mortem de casos con ECJ y sobre la corteza cerebral de un modelo murino de la EEB, esto es, de ratones transgénicos para la PrP bovina infectados con EEB en diferentes estadíos de desarrollo de la enfermedad. Los resultados obtenidos muestran, en primer lugar, un deterioro de las vías de señalización de los receptores metabotrópicos de glutamato de grupo I en la corteza frontal de ECJ así como en la corteza cerebral de un modelo murino de la EEB asociado al progreso de la enfermedad, lo cual sugiere que las fosfolipasas y los elementos constituyentes de la transducción de señales de dicha vía son particularmente sensibles a las EETs. En segundo lugar, se ha encontrado un incremento de la expresión y la actividad de los receptores A1 de adenosina en la corteza frontal de casos con ECJ así como un aumento de la expresión de estos receptores en corteza cerebral de un modelo murino de la EEB asociado al progreso de la enfermedad. El incremento en los niveles de A1Rs puede ser una respuesta al daño neuronal, teniendo en cuenta su papel neuroprotector en el SNC. En tercer lugar, se ha detectado un incremento de la expresión de AQP1 y AQP4 en la corteza frontal de casos con ECJ así como en la corteza cerebral de un modelo murino de la EEB asociado al progreso de la enfermedad. El incremento de la expresión de AQPs se puede asociar a una alteración de la homeostasis celular y a la formación de vacuolas que pueden contribuir al cambio espongiforme característico de las enfermedades priónicas. Por último, se ha encontrado un descenso de los niveles proteicos de los factores de transcripción c-fos y CREB en la corteza frontal de casos con ECJ, en contraste con el mantenimiento de los niveles de las MAPKs. El agotamiento de c-fos y CREB puede inducir neurodegeneración en estadios terminales de ECJ, considerando su papel mediador en los fenómenos de muerte y supervivencia celular.Si bien, los resultados que se desprenden de esta tesis mejoran la comprensión de los fenómenos celulares y moleculares que acompañan a la patología de las EETs, serán necesarios estudios ulteriores con modelos celulares y animales para conocer con mayor exactitud de qué modo y en qué medida contribuye el prión a estas alteraciones. / Prion diseases, also known as Transmissible Spongiform Encephalopathies (TSEs), are a group of fatal neurodegenerative diseases that have had an important social, political and economical impact in the last decades, according to their potential transmissibility. TSEs affect human and animals, and their incubation period is long. They caused death after a few months from the first clinical symptoms. TSEs origin is associated to the presence, multiplication and deposition of an abnormal protein called prion. Prion, also called PrPSc, is an abnormal form of the cellular prion protein (PrPC), which is a cell-anchored glycoprotein expressed in a wide range of animal tissues but it is enriched into the central nervous system (CNS). Prions are partially resistant to protease digestion and also resistant to conventional physical-chemical treatments. Prions are able to recruit PrPC leading to the propagation of the pathogenic conformation. Prions are transmissible, not only between individuals from the same specie, but also between individuals from different species.The most important animal TSEs are scrapie, affecting sheep and goats, and Bovine Spongiform Encephalopathy (BSE) affecting cows (also called mad cow disease). In humans, TSEs include Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker syndrome (GSS), Fatal Familial Insomnia (FFI) and Kuru. CJD has an incidence of 1 or 2 cases per million of population within a year around the world, affects both men and women and causes dementia, myoclonia and cerebellar ataxia. Neuropathologically, CJD is characterized by neuron loss, astrocytosis, mycroglyosis and spongiform change. The presence of 14-3-3 protein in CSF and a typical EEG are diagnosis factors but final diagnosis is done by PrPSc detection by immunohistochemistry of Western blotting. The impact of TSEs on public and animal health in the last decades was originated, mainly, by the BSE epidemic which affected United Kingdom in the nineties. This epidemic was attributed to the enrichment of cows food with proteins derived from scrapie-infected sheep. Due to the inter-specific transmissibility of prions, cows became infected from consumption of cow-derived food. CJD has a sporadic origin in 85% of cases. This origin is associated to the presence of residual prions into the brain or to punctual mutations in the prion protein gene (PRNP) or to a spontaneous PrP conversion due to physical or chemical environmental changes. The rest of CJD cases have an inherited or an iatrogenic transmission.The general purpose of this thesis is the study of TSEs directed to increase knowledge about cellular and molecular mechanisms involved in the neuropathology of prion diseases. It can be assumed that the multiplication and accumulation of prions into the CNS are likely the causes of TSEs, but also that mechanisms associated to neuropathologycal alterations linked to prion pathology have probably a multifactor origin. In this scenario, the alterations in neurotransmission and the dysfunction of many groups of proteins related to cell survival are considered crucial in the development of prion diseases and their neuropathological features. Giving some consideration to these observations, this thesis has been focused in the study of the role of some groups of proteins in neurotransmission, spongiform change and neuron loss. More specifically, we have studied signalling pathways linked to glutamate and adenosine transmission, water channel brain aquaporins in relation with vacuolization and spongiform change, and MAPKs signaling in relation with neurodegeneration. All these studies have been done on human cerebral cortex from neurological post-mortem material of CJD cases and on the cerebral cortex of BSE-infected PrP-bovine transgenic mice at different stages of disease progression. The results obtained show, first of all, impaired group I metabotropic glutamate transmission and also increased adenosine A1 receptor signaling in the cerebral cortex of CJD cases and, on the other hand, in the cerebral cortex of a BSE murine model with disease progression. Increased adenosine A1 receptor levels could be a response to neuronal damage due to the neuroprotective role of these receptors into the brain. In addition, we have found an increased AQP1 and AQP4 expression in the cerebral cortex of CJD cases and in the cortex of a BSE murine model with disease progression. Increased AQPs expression in brain could be associated with abnormal cell homeostasis and with the formation of vacuoles which can lead to spongiform change. Finally, we have also found decreased c-fos and CREB levels, in both inactivated and activated forms, in frontal cortex of CJD cases and also in the cerebral cortex of a BSE murine model with disease progression. Decreased c-fos and CREB transcription factors are associated with cell death and cell death, so could lead to neurodegeneration in terminal stages of CJD. Although the results presented here can improve the understanding of cellular and molecular events involved in TSEs pathology, further studies using animals and cell models would be necessary to know more exactly whether prions can lead to these alterations.

INTRODUCCIÓN: Las encefalopatías espongiformes transmisibles (EET) o enfermedades por priones son un grupo de enfermedades neurodegenerativas letales que afectan al ser humano y a otros mamíferos. El agente causal de estas enfermedades es el prión, que es una isoforma anómala de una proteína celular normal codificada en el gen PRNP. La Organización Mundial de la Salud, en 1998, estableció, para el diagnóstico de las enfermedades priónicas humanas, las categorías de definitivo, probable y posible. El diagnóstico se confirma en el estudio neuropatológico, o, en el caso de las formas genéticas, en el análisis genético si este demuestra la presencia de una mutación patogénica en el gen de PRNP. El diagnóstico de ECJ in vivo, con categoría de probable, se realiza cuando a una serie de criterios clínicos se añade la presencia de complejos periódicos en el EEG o la prueba de proteína 14-3-3 positiva en el caso de las formas esporádicas. Con el nombre de proteína 14-3-3 se denomina a una familia de proteínas especialmente abundante en sistema nervioso central y su detección a través de un método de inmunoblot, se demostró que se asociaba al diagnóstico de ECJ esporádica.OBJETIVOS: O1: Estudiar la evolución de la demanda y la validez de la prueba de proteína 14-3-3 durante el periodo 1997-2000 en España. O2: Mejorar la sensibilidad y especificidad de la prueba de la proteína 14-3-3 para el diagnóstico de enfermedad de Creutzfeldt-Jakob (ECJ) y analizar los patrones atípicos en el resultado de la prueba. O3: Analizar el polimorfismo del exon 1 del gen Tau en enfermedades por priones y determinar si este modifica la predisposición a padecer enfermedades priónicas o la expresión clínica de estas. O4: Caracterizar clínica y genéticamente las enfermedades por priones humanas en Cataluña en el periodo 1993-2001 TRABAJOS que conforman esta tesis doctoral: T1: Utilización y validez de la prueba de la proteína de 14-3-3 en el diagnóstico de enfermedades priónicas: estudio prospectivo de 4 años. Medicina Clínica 2003 (en prensa). T2: Isoformas de la proteína 14-3-3 y patrones atípicos en la prueba de la 14-3-3 en el diagnóstico de la enfermedad de Creutzfeldt-Jakob. Neuroscience Letters 2002; 320: 69-72. T3: Análisis del polimorfismo del exon 1 del gen Tau en las encefalopatías espongiformes transmisibles. Journal of Neurology 2002; 249: 938-939. T4: Características clínicas y genéticas de las enfermedades priónicas humanas en Cataluña (1993-2001). CONCLUSIONES: C1. El número de pruebas de proteína 14-3-3 en LCR solicitadas a nuestro laboratorio se ha incrementado a lo largo del periodo 1997-2000. Paralelamente, han aumentado el número de falsos positivos y disminuido el valor predictivo positivo de la prueba . Las causas más frecuentes de FP pueden y deben ser excluidas por la evaluación clínica y las pruebas complementarias apropiadas. Un resultado negativo es altamente predictivo de ausencia de la enfermedad en nuestro medio. C2. Los anticuerpos frente a las diferentes isoformas de proteína 14-3-3 no aumentan la sensibilidad ni la especificidad obtenida con el anticuerpo estándar para el diagnóstico de ECJ. La banda inferior característica de patrones de positividad atípicos de la prueba de 14-3-3, se origina por una reacción cruzada del anticuerpo anti-proteína 14-3-3 con las cadenas ligeras de immunoglobulinas libres presentes en el LCR. C3. No existe evidencia, en nuestra población, de asociación entre el polimorfismo del exón 1 del gen Tau y la predisposición a padecer enfermedades priónicas, o el perfil de expresión clínico de la enfermedad. C4. La distribución de los subtipos etiológicos y de las características genéticas y clínicas de los pacientes catalanes con enfermedades priónicas es similar a lo descrito en otras poblaciones europeas. Hasta un tercio de las formas genéticas diagnosticadas carecían de antecedentes familiares conocidos. Las formas valina-valina de ECJ esporádica y las formas genéticas presentan con más frecuencias manifestaciones clínicamente atípicas. No se ha detectado ningún caso de variante de ECJ en Cataluña en el periodo estudiado.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 196-228).

Ratos que não expressam a proteína prion celular (PrPc) são mais sensíveis a crises epilépticas induzidas por diferentes protocolos. O hipocampo desses animais apresenta um brotamento supragranular de fibras musgosas semelhante ao observado em pacientes com epilepsia de lobo temporal relacionada a esclerose hipocampal (ELT-EH). Esses achados sugerem que a PrPc pode estar envolvida na epileptogênese da ELT-EH. Nós estudamos nessa tese a localização imunoistoquímica da PrPc no hipocampo de animais submetidos ao modelo de epilepsia de lobo temporal por pilocarpina (MELTP)em diferentes tempos de status epilepticus em ratos. Nesse trabalho induzimos estado de mal epileptico (EE) com o uso de pilocarpina em três diferentes grupos de ratos Wistar adultos. Os animais foram sacrificados 18 horas, 5 dias e 2 meses após a indução do EE. Os resultados foram comparados com cérebros controles de ratos que receberam injeções de solução salina. As lâminas foram processadas para coloração por hematoxilinaeosina, imunohistoquímica e neo-Timm. Observamos um aumento da expressão de PrPc nas regiões CA1 e CA3 do hipocampo 18 horas depois da injeção de pilocarpina. Essa expressão aumentada persistiu na região CA1 no quinto dia após a injeção. Não observamos diferenças significativas na expressão de PrPc durante a fase aguda do MELTP nas regiões CA2 e granular do hipocampo. No grupo crônico (2 meses) a PrPc foi observada na mesma localização em que se observou brotamento de fibras musgosas. Concluímos com esse trabalho que a expressão da PrPc é diferente nas diversas fases do modelo de epilepsia induzido por pilocarpina. A expressão transitória da proteína prion durante a fase aguda do modelo pode refletir mudanças de expressão visando tornar as células mais resistentes ao dano induzido pelas crises convulsivas. Alternativamente, essa expressão aumentada pode estar relacionadas à apotose ou então às fases iniciais da neuroplasticidade. A expressão de PrPc na mesma região dos brotamentos de fibras musgosas na fase crônica pode estar relacionada à neuroplasticidade, epileptogênese, neurotransmissão ou, ainda, estar implicada na proteção celular contra crises convulsivas recorrentes. Devido aos diversos achados relacionados a PrPc, sugerimos que o modelo de epilepsia do lobo temporal induzido pela pilocarpina possa ser um interessante modelo para o estudo do papel fisiológico da PrPc. / Mice lacking cellular prion protein (PrPc) are more sensitive to seizures induced by four different pharmacological protocols. The hippocampal formation of these animals exhibits supragranular mossy fiber sprouting which resembles that observed in patients with mesial temporal lobe epilepsy related to hippocampal sclerosis (MTLEHS). These findings suggest that the PrPc may be involved in epileptogenesis in MTLE-HS. Here we investigated the immunohistochemical localization of the PrPc in the hippocampus of animals submitted to the pilocarpine model of temporal lobe epilepsy (PMTLE). Status epilepticus (SE) was induced with pilocarpine in three different groups of adult Wistar rats. The animals were sacrificed 18 hours, 5 days, and 2 months after SE induction and the results were compared to the respective saline-injected control animals. Slices were processed for hematoxylin-eosin, PrPc immunohistochemistry and neo-Timm .PrPc was increased in the CA1 and in CA3 regions of the hippocampus 18 hours after pilocarpine injection. PrPc continued to be increased in the CA1 region of the hippocampus five days after pilocarpine injection. In the CA2 and granular regions of the hippocampus we did not observe significant differences in PrPc expression during the acute phase of PMTLE. In the chronic group, PrPc was expressed co-localized with mossy fiber sprouting. Cellular prion protein is differentially expressed at different phases of the pilocarpine model of epilepsy. Transient expression of PrPc during the acute phase of the pilocarpine model may reflect changes which may render cells more resistant to seizure-induced damage and may be related to apoptosis or may to the initial phases of neuroplasticity. During the chronic period, PrPc is co-expressed in the same regions of mossy fiber sprouting. In chronic animals, PrPc might be related to neuroplasticity, epileptogenic processes, neurotransmission, or alternatively may be implicated in cellular protection against recurrent seizures.

Prion diseases are fatal transmisible neurodegenerative and infectious disorders (TSEs) of humans and animals, characterized by structural transition of the host-encoded cellular prion protein (PrPC) into the aberrantly folded pathologic isoform PrPSc. The main aim of this work is to summarize present information about prion diseases and their possibilities of determination pointed to electrochemical techniques. For this purpose cyclic voltammetry (CV), differential pulse voltammetry, differential pulse voltammetry Brdicka reaction and chronopotentiometric stripping analysis (CPSA) were used. The estimated detection limits were 32 ug/ml by CV, 16 ug/ml by DPV, 16 ug/ml by DPV -- Brdicka reaction and 8 ug/ml by CPSA. Subsequently, the influence of heat denaturation was observed. It clearly follows from the obtained results that signals of prion decreased linearly depending on the duration of the heat treatment at 99°C for various time intervals 0, 15, 30, 45, and 60 min. Moreover, we aimed our attention on studying of prion protein interaction with CdTe quantum dots (QDs) using electrochemistry. Primarily, we characterized electrochemical properties of QDs and the detection limit at 100 fg/ml was estimated. Further, electrochemical study of prion and QD interactions was carried out to find the most suitable conditions for sensitive detection of prion proteins. Detection limit (3 S/N) was estimated as 1 fg in 5 ul. This makes labeling of proteins with QDs of great importance due to easy applicability and possibility to use in miniaturized devices, which can be used in situ. This should open new possibilities how to determine the presence of these proteins on surgical equipment and other types of materials, which could be contagious.