Mutation in the PCSK9 gene in Omani Arab subjects with autosomal dominant hypercholesterolemia and its effect on PCSK9 protein structure

Proprotein convertase subtilisin/kexin type [PCSK9] is a crucial protein in LDL cholesterol [LDL-C] metabolism by virtue of its pivotal role in the degradation of the LDL receptor. Mutations in the PCSK9 gene have previously been found to segregate with autosomal dominant familial hypercholesterolemia [ADFH]. In this study, DNA sequencing of the 12 exons of the PCSK9 gene has been performed for two patients with a clinical diagnosis of familial hypercholesterolemia where mutation in the LDL-receptor gene hasn't been excluded. One missense mutation was detected in the exon 9 PCSK9 gene in the two ADFH patients. The patients were found to be heterozygote for Ile474Val [SNP rs562556] Using an array of in silico tools, we have investigated the effect of the above mutation on different structural levels of the PCSK9 protein Although, the mutation has already been reported in the literature for other populations, to the best of our knowledge this is the first report of a mutation in the PCSK9 gene from the Arab population, including the Omani population

Pro-protein convertase-2/carboxypeptidase-E mediated neuropeptide processing of RGC-5 cell after in vitro ischemia / 神经科学通报·英文版

<p><b>OBJECTIVE</b>To observe the change of the neuropeptide pro-protein processing system in the ischemic retina ganglion cell-5 (RGC-5) cells, pro-protein convertase-2 (PC2), carboxypeptidase-E (CPE) and preproneuropeptide Y (preproNPY) protein levels in the ischemic RGC-5 cells and conditioned medium were analyzed.</p><p><b>METHODS</b>The RGC-5 cell was differentiated in 0.1 mumol/L staurosporine for 24 h and then stressed by different doses of oxygen and glucose deprivation (OGD). The acute or chronic OGD-induced cell death rates were obtained by using PI or TUNEL staining. The protein expression levels were determined by using the Western blot method and PC2 activity analysis.</p><p><b>RESULTS</b>The ischemia caused substantial cell death in an OGD dose-dependent manner. In the cells, proPC2 and preproNPY protein levels gradually increased whereas proCPE gradually decreased. After OGD, PC2 activity was decreased. In the conditioned medium, proPC2 and PC2 proteins gradually decreased whereas proCPE, CPE, and preproNPY proteins gradually increased.</p><p><b>CONCLUSION</b>These results demonstrated that OGD inhibited the neuropeptide pro-protein processing system by reducing PC2 activity and the maturation of proPC2. The aggregation of the pro-proteins and the increase of the active CPE excision adversely exacerbated the cell injury. The pro-protein processing system might play a critical role in the ischemic stress of RGC-5 cells.</p>