Random Molecule Generator

Nevertheless, the most attractive hypothesis is probably that the clearance of A deposits depends on the isoform of APOE, because APOE binds to A peptides more strongly than does APOE. APOE and APOE, but not APOE, form dimers that might contribute to the regulation of A degradation, and APOE levels in the plasma and brain of humans carrying the APOE allele are lower than in APOE carriers. In support of this finding, more amyloid is deposited in the brains of mice expressing human APOE compared with those expressing APOE or APOE. LRP seems to participate in the uptake and clearance of A, because these processes are decreased when LRP is eliminated in mouse forebrain neurons. The expression of the ABC transporter ABC has also been linked to AD, and to the regulation of {|reasch {Endurobol|Amiodarone cholesterol and APOE homeostasis in the brain. In addition, the level of APOE in the brain was lower in these mice than in wildtype control mice.When ABCA knockout mice were crossed with mouse models of AD, the lack of ABCA did not affect A production.However, the poorly lipidated APOE particles that were generated in the ABCA knockout mice seemed to be responsible for increasing the amyloid load. Consistent with these findings, overexpression of ABCA in AD mice reduced amyloid deposition. Overall, the available data indicate that profound alterations in cholesterol metabolism occur in AD, but whether these changes are the cause of the neurodegeneration remains uncertain.Cholesterol and HD HD is a progressive, autosomal dominant neurodegenerative disease that is characterized by cognitive and motor deficits.This disorder is caused by a polyglutamate expansion. The neurons in the brain that die when exposed to the toxic mutant huntingtin protein are primarily the striatal and cortical neurons. The cholesterol biosynthetic pathway is markedly altered in the brains of humans and mice with HD. For example, expression of mutant huntingtin in brainderived cells reduced the processing of the sterol responseelement binding protein. In addition, the expression of SREBP target genes was downregulated, and cholesterol biosynthesis and cellular cholesterol levels were reduced. Consistent with these observations, the level of cholesterol in the striatum and cortex of a mouse model of HD is lower than in nonHD mice. Furthermore, the addition of cholesterol to striatal neurons expressing mutant huntingtin increased their survival, suggesting that the deficit in cholesterol contributes directly to the neurological phenotype of HD. Nevertheless, no clear molecular mechanism has yet emerged that would directly relate alterations in cholesterol biosynthesis in the brain to the neuronal dysfunction that characterizes HD.The mechanisms responsible for these alterations are not yet entirely clear but are being actively investigated.The administration of LDOPA, which is converted into dopamine, temporarily reduces the motor symptoms and is commonly used to treat the disease.A role for cholesterol in the neurodegenerative pathology of PD remains controversial.Intriguingly, however, the synuclein protein contains two cholesterolbinding domains, and cholesterol seems to modulate synuclein aggregation.Some studies indicate that a higher level of plasma cholesterol correlates with a lower incidence of PD, whereas other studies have reported that individuals with a high plasma cholesterol level have an increased risk of developing PD.

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