Overexpression of Parkinson's disease-associated alpha-synucleinA53T by recombinant adeno-associated virus in mice does not increase the vulnerability of dopaminergic neurons to MPTP

Mutations in the alpha-synuclein gene are linked to a rare dominant form of familial Parkinson's disease, and alpha-synuclein is aggregated in Lewy bodies of both sporadic and dominant Parkinson's disease. It has been proposed that mutated alpha-synuclein causes dopaminergic neuron loss by enhancing the vulnerability of these neurons to a variety of insults, including oxidative stress, apoptotic stimuli, and selective dopaminergic neurotoxins, such as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). To test this hypothesis in vivo, we overexpressed human alpha-synuclein(A53T) in the substantia nigra of normal and MPTP-treated mice by rAAV-mediated gene transfer. Determination of dopaminergic neuron survival, striatal tyrosine hydroxylase fiber density, and striatal content of dopamine and its metabolites in rAAV-injected and uninjected hemispheres demonstrated that alpha-synuclein(A53T) does not increase the susceptibility of dopaminergic neurons to MPTP. Our findings argue against a direct detrimental role for (mutant) alpha-synuclein in oxidative stress and/or apoptotic pathways triggered by MPTP, but do not rule out the possibility that alpha-synuclein aggregation in neurons exposed to oxidative stress for long periods of time may be neurotoxic.     

Heterostereocomplexes prepared from d-poly(lactide) and leuprolide. I. Characterization

Heterostereocomplexes between d-PLA and l-peptides, obtained by spontaneous precipitation from acetonitrile solution, were characterized by thermal analysis and microscopic techniques. Differential scanning calorimetry showed two transition endotherms, one for the alpha form that melts at 178 degrees C and one for the beta form of PLA that melts at 169 degrees C. A linear correlation was found between the enthalpy of both melt temperatures and the peptide concentration. The complexation was monitored by a change in morphology, which was imaged by AFM-tapping mode. The initial fibrous network of d-PLA changed to uniform disks of 100 nm in diameter and 2.5 nm in height of the heterostereocomplex. Rhodamine B labeled leuprolide was complexed selectively to d-PLA, which was chemically bound onto mica plates. Addition of l-PLA to the complex enabled displacement of the peptide, which was observed by fluorescent spectrometry and confocal microscopy. These results provide a method, which enables one to obtain an expression for the relative interaction strength between various stereoselective polymers and polypeptides with opposite enantiomeric configuration.     

Gene sharing, lens crystallins and speculations on an eye/ear evolutionary relationship

The crystallins comprise 80–90% of the water-soluble proteinsof the transparent, cellular, refractive eye lens and are responsiblefor its optical properties. Comparative studies have establishedthat the crystallins are surprisingly diverse and often differamong species in a taxon-specific fashion. In general, the crystallinsare derived from or identical to metabolic enzymes or stress(small heat shock) proteins that are expressed to a lesser extentin other tissues where they have non-refractive roles. We callthe phenomenon of having the small heat shock protein or enzymeand lens crystallin encoded in the identical gene "gene sharing";examples include small heat shock protein/     

Structurally Normal Corneas in Aldehyde Dehydrogenase 3a1-Deficient Mice

We have constructed an ALDH3a1 null mouse to investigate the role of this enzyme that comprises nearly one-half of the total water-soluble protein in the mouse corneal epithelium. ALDH3a1-deficient mice are viable and fertile, have a corneal epithelium with a water-soluble protein content approximately half that of wild-type mice, and contain no ALDH3a1 as determined by zymograms and immunoblots. Despite the loss of protein content and ALDH3a1 activity, the ALDH3a1(-/-) mouse corneas appear indistinguishable from wild-type corneas when examined by histological analysis and electron microscopy and are transparent as determined by light and slit lamp microscopy. There is no evidence for a compensating protein or enzyme. Even though the function of ALDH3a1 in the mouse cornea remains unknown, our data indicate that its enzymatic activity is unnecessary for corneal clarity and maintenance, at least under laboratory conditions.     

Expression of the murine alpha B-crystallin gene in lens and skeletal muscle: identification of a muscle-preferred enhancer.

The alpha B-crystallin gene is expressed at high levels in lens and at lower levels in some other tissues, notably skeletal and cardiac muscle, kidney, lung, and brain. A promoter fragment of the murine alpha B-crystallin gene extending from positions -661 to +44 and linked to the bacterial chloramphenicol acetyltransferase (CAT) gene showed preferential expression in lens and skeletal muscle in transgenic mice. Transfection experiments revealed that a region between positions -426 and -257 is absolutely required for expression in C2C12 and G8 myotubes, while sequences downstream from position -115 appear to be determinants for lens expression. In association with a heterologous promoter, a -427 to -259 fragment functions as a strong enhancer in C2C12 myotubes and less efficiently in myoblasts and lens. Gel shift and methylation interference studies demonstrated that nuclear proteins from C2C12 myoblasts and myotubes specifically bind to the enhancer.