No abstract

Adiponectin, a hormone predominantly originated from adipose tissue, has exhibited potent anti-inflammatory properties. Accumulating evidence suggests that autophagy induction plays a crucial role in anti-inflammatory responses by adiponectin. However, underlying molecular mechanisms are still largely unknown. Association of Bcl-2 with Beclin-1, an autophagy activating protein, prevents autophagy induction. We have previously shown that adiponectin-induced autophagy activation is mediated through inhibition of interaction between Bcl-2 and Beclin-1. In the present study, we examined the molecular mechanisms by which adiponectin modulates association of Bcl-2 and Beclin-1 in macrophages. Herein, we demonstrated that globular adiponectin (gAcrp) induced increase in the expression of AUF1 and ZFP36L1, which act as mRNA destabilizing proteins, both in RAW 264.7 macrophages and primary peritoneal macrophages. In addition, gene silencing of AUF1 and ZFP36L1 caused restoration of decrease in Bcl-2 expression and Bcl-2 mRNA half-life by gAcrp, indicating crucial roles of AUF1 and ZFP36L1 induction in Bcl-2 mRNA destabilization by gAcrp. Moreover, knock-down of AUF1 and ZFP36L1 enhanced interaction of Bcl-2 with Beclin-1, and subsequently prevented gAcrp-induced autophagy activation, suggesting that AUF1 and ZFP36L1 induction mediates gAcrp-induced autophagy activation via Bcl-2 mRNA destabilization. Furthermore, suppressive effects of gAcrp on LPS-stimulated inflammatory mediators expression were prevented by gene silencing of AUF1 and ZFP36L1 in macrophages. Taken together, these results suggest that AUF1 and ZFP36L1 induction critically contributes to autophagy induction by gAcrp and are promising targets for anti-inflammatory responses by gAcrp.

Oxidative stress due to overproduction of reactive oxygen species (ROS) plays a major role in inflammation, cancer, and neurodegenerative disorders. In this study, 60 chalcone derivatives with fluorine (F), trifluoromethyl (CF3), trifluoromethoxy (OCF3), chlorine (Cl), and bromine (Br) in ring A and with or without hydroxy (OH) in ring B were designed, synthesized, and screened for inhibitory activity against lipopolysaccharide (LPS)‐stimulated ROS production in RAW 264.7 macrophages. Structure–activity relationship study revealed the importance of a hydroxyl moiety in ring B for enhancing inhibitory activity of ROS production. Furthermore, a hydroxyl group at the ortho‐position is more essential for inhibition of ROS production followed by meta‐ and para‐positions. Among all, compound 27 that contains para‐chlorine moiety in ring A and ortho‐hydroxy in ring B displayed the strongest inhibitory activity (IC50 = 3.42 μM) against LPS‐stimulated ROS production in RAW264.7 macrophages.

Adiponectin exhibits potent antitumor activities. Herein, we examined the molecular mechanisms underlying suppression of tumor growth by globular adiponectin ( gA crp). We demonstrated that gA crp suppressed B‐cell lymphoma 2 (Bcl‐2) expression, an anti‐apoptotic gene, by inducing its mRNA destabilization, which was accompanied with a decrease in cell viability and increased caspase‐3 activity in hepatic cancer cells. In addition, gA crp increased expression of tristetraprolin ( TTP ) and AU‐rich element RNA‐binding protein 1 ( AUF 1), which are mRNA stability regulatory proteins. Moreover, gA crp‐induced suppression of Bcl‐2 expression was abrogated by knockdown of TTP or AUF 1. These data indicate that gA crp induces apoptosis of hepatic cancer cells by TTP ‐ and AUF 1‐mediated Bcl‐2 mRNA destabilization, and further suggest that TTP and AUF 1 are novel targets mediating the antitumor activity of adiponectin.

A new series of thirty‐two fluorinated and/or hydroxylated 2‐arylidene‐1‐indanone derivatives were systematically designed, synthesized, and evaluated for their inhibitory activity against LPS‐stimulated ROS production in RAW 264.7 macrophages. 5/6‐Fluoro‐1‐indanone or 4‐, 5‐, 6‐, or 7‐hydroxyindanone moiety along with ortho‐, meta‐, or para‐hydroxyphenyl, furanyl or thiophenyl moiety was prepared and evaluated. Among the synthesized compounds, compound 11 possessing 6‐hydroxy‐1‐indanone moiety along with 5‐chlorothiophenyl moiety was found to have the most potent inhibitory effect on the production of ROS in LPS‐stimulated RAW 264.7 macrophages with an IC50 value of 3.29 μM.