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Elevated amyloid β production in senescent retinal pigment epithelium, a possible mechanism of subretinal deposition of amyloid β in age-related macular degeneration
- Source :
- Biochemical and Biophysical Research Communications. 423:73-78
- Publication Year :
- 2012
- Publisher :
- Elsevier BV, 2012.
-
Abstract
- Age-related macular degeneration (AMD) is the most common cause of legal blindness in the elderly individuals in developed countries. Subretinally-deposited amyloid β (Aβ) is a main contributor of developing AMD. However, the mechanism causing Aβ deposition in AMD eyes is unknown. Aging is the most significant risk of AMD, thus, we examined the effect of aging on subretinal Aβ deposition. mRNAs and cell lysates were isolated from retinal pigment epithelial (RPE) cells derived from 24-month-old (24M RPE) and 2-month-old (2M RPE) C57BL/6 mice. Aβ concentration in culture supernatants was measured by ELISA. Activity and expression of proteins that regulate Aβ level were examined by activity assay and real time PCR. Effect of β-secretase (BACE) on Aβ production was examined by siRNA silencing. Aβ amounts in supernatants of 24M RPE were significantly higher than 2M RPE. Activity and mRNA levels of neprilysin, an Aβ degrading enzyme, were significantly decreased in 24M RPE compared to 2M RPE. PCR analysis found that BACE2 was significantly more abundantly expressed than BACE1 in RPE cells, however, inactivation of BACE2 gene did not affect Aβ production. BACE1 protein amounts did not differ between 24M and 2M RPE, however, BACE1 activity was significantly higher in 24M RPE compared to 2M RPE. There were no significant changes in the activities of α- or γ-secretase between 2M and 24M RPE. In conclusion, RPE cells produce more amounts of Aβ when they are senescent, and this is probably caused by a decrease in Aβ degradation due to a reduction in the expression and activity of neprilysin and an increase in Aβ synthesis due to increased activity of BACE1.
- Subjects :
- Proteolysis
Biophysics
Cell Separation
Retinal Pigment Epithelium
Biochemistry
Macular Degeneration
Mice
chemistry.chemical_compound
medicine
Amyloid precursor protein
Animals
Aspartic Acid Endopeptidases
RNA, Messenger
RNA, Small Interfering
Molecular Biology
Neprilysin
Cellular Senescence
chemistry.chemical_classification
Amyloid beta-Peptides
Retinal pigment epithelium
medicine.diagnostic_test
biology
Retinal
Cell Biology
Anatomy
Macular degeneration
medicine.disease
Molecular biology
eye diseases
Real-time polymerase chain reaction
Enzyme
medicine.anatomical_structure
chemistry
biology.protein
sense organs
Amyloid Precursor Protein Secretases
Subjects
Details
- ISSN :
- 0006291X
- Volume :
- 423
- Database :
- OpenAIRE
- Journal :
- Biochemical and Biophysical Research Communications
- Accession number :
- edsair.doi.dedup.....f37899063a8f00accd71c0e70d1433c6