The number of people living with Alzheimer's disease (AD) is increasing worldwide as populations age. A hallmark of AD is the accumulation of amyloid-β (Aβ) in the brain, and pathways regulating amylo Show more
The number of people living with Alzheimer's disease (AD) is increasing worldwide as populations age. A hallmark of AD is the accumulation of amyloid-β (Aβ) in the brain, and pathways regulating amyloid-β precursor protein (AβPP) processing are of major interest for disease-modifying and preventive strategies such as exercise. Regular exercise is associated with a reduced risk of AD, potentially through limiting Aβ accumulation, yet the underlying cellular mechanisms remain unclear. Acute bouts of exercise induce the release of circulating signalling molecules that may influence AβPP metabolism. To investigate the effects of exercise on AβPP processing, human induced pluripotent stem cell (iPSC)-derived neurons and astrocytes were treated with serum collected before and immediately after high-intensity exercise. Both healthy control and familial AD (PSEN1 A246E) neurons and astrocytes were independently exposed to 10 % pre- or post-exercise serum for 30 min, after which markers of AβPP processing were quantified. Post-exercise serum contained increased amounts of Lacate, BDNF, IL-6, sAβPPα, and Aβ₁-₄₂, and reduced neprilysin activity (p < 0.05). Treatment with post-exercise serum acutely elevated ADAM10 activity in neurons, which was replicated by spiking lactate in pre-exercise serum. sAβPPα was also increased in PSEN1 neurons following post exercise serum treatment with increased Aβ₁-₄₂ secretion in both PSEN1 neurons and astrocytes (p < 0.05). These findings demonstrate that human post-exercise serum can modulate AβPP processing in iPSC-derived neural cells. This supports the concept that circulating exercise-induced factors can influence neuronal pathways relevant to AD pathology. Show less
Dyggve Melchior Clausen syndrome (DMC) is a severe autosomal recessive skeletal dysplasia associated with mental retardation. Direct sequencing of genomic DNA has identified causative mutations in the Show more
Dyggve Melchior Clausen syndrome (DMC) is a severe autosomal recessive skeletal dysplasia associated with mental retardation. Direct sequencing of genomic DNA has identified causative mutations in the gene Dymeclin (chromosome 18q12-21), with the majority predicting the generation of a truncated protein product. To carry out molecular genetic studies in three DMC kindreds. Two novel nonsense mutations and two complex genomic duplication events resulting in exon repetition were identified. Exon dosage assessment or mRNA analysis, in addition to direct genomic DNA sequencing, should be employed in the investigation of DMC affected individuals. Genomic duplication may be the causative mutation mechanism in other autosomal recessive disorders. Show less
A novel gene encoding a 2.2 kilobase transcript has been isolated from the Xp21.1 region of the human X chromosome by exon amplification. The gene, called EXT1, spans 80 kilobases and contains 12 exon Show more
A novel gene encoding a 2.2 kilobase transcript has been isolated from the Xp21.1 region of the human X chromosome by exon amplification. The gene, called EXT1, spans 80 kilobases and contains 12 exons, at least two of which are alternatively spliced and have predicted products of 464 and 471 amino acids respectively. Conceptual translation of the open reading frames shows one product with a 30 amino acid signal peptide, which is absent from the alternative transcript, followed by three complement control protein domains, a hydrophobic region with a possible role in membrane anchorage and short 17 amino acid putative cytoplasmic carboxyl terminus. An alternative first exon contains a 39 amino acid open reading frame which is rich in serine and threonine residues and contains a potential chondroitin/dermatan sulphate attachment site. Northern analysis showed ETX1 expression within the retina and heart with lower levels in several other tissues. Since ETX1 lies within the region thought to contain the x-linked retinitis pigmentosa (xIRP) gene, RP3, it was screened for mutation within a set of 45 xIRP patients using single strand conformation analysis and/or chemical cleavage of mismatch using reverse transcription/polymerase chain reaction amplification of polyA+RNA from blood cells. Three low frequently variants (17-23Ldel, P225S, S413F) were found in both patients and controls; one of which (P225S) was found in four of 45 unrelated patient chromosomes and one of 178 control chromosomes (p <0.001). The allelic association between P225S and xIRP alleles suggests a common ancestral chromosome bearing the P225S variant and an RP3 mutation at a neighbouring locus. Show less