Differential contribution of possible pattern‐recognition receptors to advanced glycation end product–induced cellular responses in macrophage‐like RAW264.7 cells

• Published in: Biotechnology and applied biochemistry 2020-03, Vol.67 (2), p.265-272
• Main Authors: Watanabe, Masahiro, Toyomura, Takao, Wake, Hidenori, Liu, Keyue, Teshigawara, Kiyoshi, Takahashi, Hideo, Nishibori, Masahiro, Mori, Shuji
• Format: Article
• Language: English
• Subjects: advanced glycation end products; Advanced glycosylation end products; Age; Animals; Cloning; CRISPR; CRISPR-Associated Protein 9 - genetics; CRISPR-Associated Protein 9 - metabolism; CRISPR-Cas Systems - genetics; Extracellular signal-regulated kinase; Gene Editing; Genome editing; Genomes; Glycation End Products, Advanced - genetics; Glycation End Products, Advanced - metabolism; Glycosylation; Inflammatory diseases; Kinases; knockout; Macrophages; Macrophages - metabolism; Mice; Pathogenesis; Pattern recognition; Phosphorylation; RAW 264.7 Cells; receptor for advanced glycation end products; Receptor for Advanced Glycation End Products - genetics; Receptor for Advanced Glycation End Products - metabolism; Receptors; TLR2 protein; TLR4 protein; Toll-like receptors; Toll-Like Receptors - genetics; Toll-Like Receptors - metabolism; toll‐like receptor; Transcription; Tumor necrosis factor-TNF; Tumor necrosis factor-α
• ISSN: 0885-4513; 1470-8744
• DOI: 10.1002/bab.1843

Advanced glycation end products (AGEs) are considered to be related to the pathogenesis of some inflammatory diseases. AGEs were reported to stimulate the receptor for AGEs (RAGE), which causes inflammatory reactions. However, recently, toll‐like receptors (TLRs), in addition to RAGE, have been reported to be related to AGE‐mediated cellular responses, and it remains unclear which receptor is responsible for AGE recognition. To reveal the role of pattern‐recognition receptors, including TLRs and/or RAGE, in AGE‐mediated cellular responses, we generated macrophage‐like RAW264.7 knockout (KO) cells lacking these receptors by genome editing using the CRISPR/Cas9 system and assessed AGE‐stimulated changes in these cells. Comparison of the established clones suggested that RAGE partially affects the expression of TLRs. In the KO clone lacking TLR4 and TLR2, AGE‐stimulated tumor necrosis factor alpha (TNF‐α) expression and phosphorylation of IκBα, p38, and extracellular signal‐regulated kinase (ERK) were significantly attenuated, suggesting that AGE‐mediated responses are largely dependent on TLRs. On the other hand, on comparison of the AGE‐stimulated responses between the KO clone lacking TLR4 and TLR2, and the clone lacking TLR4, TLR2, and RAGE, RAGE played little role in AGE‐stimulated TNF‐α transcription and ERK phosphorylation. Taken together, this study suggested that AGE‐stimulated inflammatory responses occur mainly through TLRs rather than RAGE. To reveal the role of possible AGE cell‐surface receptors, we generated macrophage‐like RAW264.7 KO clones lacking TLR4, TLR2, and/or RAGE. AGE‐stimulated TNF‐α expression and phosphorylation of IκBα, p38, and ERK mainly depend on TLRs. The degree of contribution of RAGE to AGE‐stimulation was slight, and only affected TNF‐α expression and ERK phosphorylation.