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The role of p62/ SQSTM 1 in IL ‐1 β ‐mediated cytokine production in retinal pigment epithelial cells
Author(s) -
Kauppinen A.,
Korhonen E.,
Piippo N.,
Hytti M.,
Kaarniranta K.
Publication year - 2017
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2017.01372
Subject(s) - autophagy , inflammasome , cytokine , microbiology and biotechnology , transfection , downregulation and upregulation , western blot , small interfering rna , retinal pigment epithelium , intracellular , chemistry , interleukin 18 , retinal , biology , cell culture , inflammation , immunology , biochemistry , apoptosis , genetics , gene
Purpose p62/ SQSTM 1 is a selective autophagy substrate being added to ubiquitinated proteins directed to lysosomal degradation. Its levels increase inside the retinal pigment epithelial ( RPE ) cells when proteasomal activity and autophagic clearance decline during aging. p62/ SQSTM 1 can also contribute to the activation of pro‐inflammatory nuclear factor kappa B ( NF ‐ κ B) or mitogen‐activated protein kinase ( MAPK ) pathways. According to our previous studies, reduced intracellular clearance promotes the NLRP 3 inflammasome‐mediated release of IL ‐1 β , which subsequently stimulates RPE cells to produce other pro‐inflammatory mediators, such as IL ‐8. In the present study, we have investigated, whether increased levels of p62/ SQSTM 1 play a role in the IL ‐1 β ‐induced response. Methods Upregulation of p62/ SQSTM 1 was induced by bafilomycin A1 or the over‐expression vector, or prevented by p62/ SQSTM 1‐specific small interfering RNA (si RNA ) transfection. Thereafter, the cells were exposed to IL ‐1 β . The release of IL ‐6 and IL ‐8 were detected using the enzyme‐linked immunosorbent assay ( ELISA ) method. In addition, the autophagy markers p62/ SQSTM 1 and LC 3 were determined using the western blot technique. Results IL ‐1 β resulted in low IL ‐6 and high IL ‐8 production in human RPE cells. p62/ SQSTM 1 and its absence were verified but they did not affect the cytokine profiles. Conclusions Our data suggest that p62/ SQSTM 1 does not play a role in the IL ‐1 β ‐induced production of pro‐inflammatory cytokines in human RPE cells.