RESUMEN
Human alpha-synuclein was identified on the basis of proteolytic fragments derived from senile plaques of Alzheimer's disease, and it is the locus of mutations in some familial forms of Parkinson's disease. Its normal function and whether it may play a direct role in neural degeneration remain unknown. To explore cellular responses to neural degeneration in the dopamine neurons of the substantia nigra, we have developed a rodent model of apoptotic death induced by developmental injury to their target, the striatum. We find by mRNA differential display that synuclein is up-regulated in this model, and thus it provides an opportunity to examine directly whether synuclein plays a role in the death of these neurons or, alternatively, in compensatory responses. Up-regulation of mRNA is associated with an increase in the number of neuronal profiles immunostained for synuclein protein. At a cellular level, synuclein is almost exclusively expressed in normal neurons, rather than apoptotic profiles. Synuclein is up-regulated throughout normal postnatal development of substantia nigra neurons, but it is not further up-regulated during periods of natural cell death. We conclude that up-regulation of synuclein in the target injury model is unlikely to mediate apoptotic death and propose that it may be due to a compensatory response in neurons destined to survive.
Asunto(s)
Dopamina/metabolismo , Regulación del Desarrollo de la Expresión Génica , Degeneración Nerviosa/metabolismo , Proteínas del Tejido Nervioso/biosíntesis , Enfermedad de Parkinson/metabolismo , ARN Mensajero/biosíntesis , Sustancia Negra/metabolismo , Secuencia de Aminoácidos , Animales , Apoptosis/efectos de los fármacos , Secuencia de Bases , Northern Blotting , Western Blotting , Células Cultivadas , Perfilación de la Expresión Génica , Genes , Hibridación in Situ , Datos de Secuencia Molecular , Degeneración Nerviosa/inducido químicamente , Degeneración Nerviosa/genética , Proteínas del Tejido Nervioso/genética , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Neurotoxinas/toxicidad , Ácido Quinolínico/toxicidad , Empalme del ARN , ARN sin Sentido/farmacología , Ratas , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Sustancia Negra/efectos de los fármacos , Sustancia Negra/crecimiento & desarrollo , Sustancia Negra/patología , Técnica de Sustracción , Sinucleínas , alfa-SinucleínaRESUMEN
The goal of this study was to characterize salivary components of titanium pellicles and to determine how experimental pellicles affect adhesion of several strains of streptococci to titanium surfaces. Titanium experimental pellicles were formed by incubation of fresh human parotid or human submandibular-sublingual saliva on pure titanium beads. Pellicle was recovered from the beads using sodium dodecyl sulfate buffer and was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting to identify adsorbed salivary components. Streptococcus anginosus, S. oralis, and S. salivarius recovered from in vivo titanium plaque and five reference strains of streptococci were used in adhesion assays to titanium beads with and without experimental salivary pellicles. The experimental pellicle formed on titanium was found to be composed of selected proteins from human parotid and human submandibular-sublingual saliva. Salivary alpha-amylase and proline-rich proteins were found in all experimental pellicles, while sIgA, high-molecular weight mucin, and proline-rich glycoproteins were detected in one of the experimental pellicles examined. Adhesion of fresh isolates and reference stains of S. anginosus, S. oralis, and S. salivarius to saliva-coated titanium was reduced compared to that of titanium without saliva coating. However, adhesion of laboratory strains of S. gordonii and S. sanguis was found to be significantly greater to experimental pellicles of human submandibular-sublingual saliva than was the adhesion of the fresh isolates, suggesting that streptococci-colonizing implant surfaces may be inherently less adhesive than other bacterial strains. This study found that salivary pellicles are selectively formed on titanium and mediate in vitro adhesion of streptococci.