Role of transient receptor potential vanilloid 2 in LPS-induced cytokine production in macrophages

• Published in: Biochemical and biophysical research communications 2010-07, Vol.398 (2), p.284-289
• Main Authors: Yamashiro, Kenji, Sasano, Tetsuo, Tojo, Katsuyoshi, Namekata, Iyuki, Kurokawa, Junko, Sawada, Naoki, Suganami, Takayoshi, Kamei, Yasutomi, Tanaka, Hikaru, Tajima, Naoko, Utsunomiya, Kazunori, Ogawa, Yoshihiro, Furukawa, Tetsushi
• Format: Article
• Language: English
• Subjects: Animals; Calcium; Calcium - metabolism; Calcium Channels - genetics; Calcium Channels - physiology; Cell Line; Cytokine; Cytokines - biosynthesis; Egtazic Acid - analogs & derivatives; Egtazic Acid - pharmacology; Gene Knockdown Techniques; I-kappa B Proteins - metabolism; Lipopolysaccharides - immunology; LPS; Macrophage; Macrophages - immunology; Mice; NF-KappaB Inhibitor alpha; Transient receptor potential vanilloid 2; TRPV Cation Channels - genetics; TRPV Cation Channels - physiology
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2010.06.082

► TRPV2 play a role in LPS-induced cytokine production in RAW macrophages. ► TRPV2 is the sole member of TRPV family expressed in RAW macrophages. ► LPS stimulate Ca2+ mobilization from intracellular store via TRPV2 and IP3 receptor. ► LPS stimulate Ca2+ entry via TRPV2 that require intracellular Ca2+ mobilization. There is considerable evidence indicating that intracellular Ca2+ participates as a second messenger in TLR4-dependent signaling. However, how intracellular free Ca2+ concentrations ([Ca2+]i) is increased in response to LPS and how they affect cytokine production are poorly understood. Here we examined the role of transient receptor potential (TRP), a major Ca2+ permeation pathway in non-excitable cells, in the LPS-induced cytokine production in macrophages. Pharmacologic experiments suggested that TRPV family members, but neither TRPC nor TRPM family members, are involved in the LPS-induced TNFα and IL-6 production in RAW264 macrophages. RT-PCR and immunoblot analyses showed that TRPV2 is the sole member of TRPV family expressed in macrophages. ShRNA against TRPV2 inhibited the LPS-induced TNFα and IL-6 production as well as IκBα degradation. Experiments using BAPTA/AM and EGTA, and Ca2+ imaging suggested that the LPS-induced increase in [Ca2+]i involves both the TRPV2-mediated intracellular and extracellular Ca2+ mobilizations. BAPTA/AM abolished LPS-induced TNFα and IL-6 production, while EGTA only partially suppressed LPS-induced IL-6 production, but not TNFα production. These data indicate that TRPV2 is involved in the LPS-induced Ca2+ mobilization from intracellular Ca2+ store and extracellular Ca2+. In addition to Ca2+ mobilization through the IP3-receptor, TRPV2-mediated intracellular Ca2+ mobilization is involved in NFκB-dependent TNFα and IL-6 expression, while extracellular Ca2+ entry is involved in NFκB-independent IL-6 production.