J Cell Biol. 2009 May 11; Shen S, Zhang P, Lovchik MA, Li Y, Tang L, Chen Z, Zeng R, Ma D, Yuan J, Yu QPromoting the degradation of Hsp90 client proteins by inhibiting Hsp90, an important protein chaperone, has been shown to be a promising new anticancer strategy. In this study, we show that an oxazoline analogue of apratoxin A (oz-apraA), a cyclodepsipeptide isolated from a marine cyanobacterium, promotes the degradation of Hsp90 clients through chaperone-mediated autophagy (CMA). We identify a KFERQ-like motif as a conserved pentapeptide sequence in the kinase domain of epidermal growth factor receptor (EGFR) necessary for recognition as a CMA substrate. Mutation of this motif prevents EGFR degradation by CMA and promotes the degradation of EGFR through the proteasomal pathway in oz-apraA-treated cells. Oz-apraA binds to Hsc70/Hsp70. We propose that apratoxin A inhibits Hsp90 function by stabilizing the interaction of Hsp90 client proteins with Hsc70/Hsp70 and thus prevents their interactions with Hsp90. Our study provides the first examples for the ability of CMA to mediate degradation of membrane receptors and cross talks of CMA and proteasomal degradation mechanisms.

Toxicol Lett. 2009 Apr 25; 186(2): 111-4Li Y, Qi XM, Xue X, Wu XF, Wu YF, Chen M, Xing GZ, Luan Y, Ren JOBJECTIVE: Many nonsteroidal anti-inflammatory drugs (NSAIDs) with diphenylamine structure induce severe hepatotoxicities. We evaluated the role of diphenylamine structure in liver injuries induced by these NSAIDs. METHODS: Effects of diphenylamine, diclofenac and tolfenamic acid on mitochondrial permeability transition (MPT) and efflux of calcium in isolated liver mitochondria as well as on cellular ATP content and mitochondrial membrane depolarization in rat primary hepatocyte cultures were examined. RESULTS: Diclofenac and tolfenamic acid induced cyclosporine A (CsA)-sensitive mitochondrial swelling and membrane depolarization in isolated liver mitochondria. Only diclofenac caused the release of calcium in isolated liver mitochondria. Diphenylamine had no effects on isolated liver mitochondria. All three compounds decreased ATP content and induced mitochondrial membrane depolarization. CsA attenuated these effects, suggesting MPT might be involved in the hepatotoxicities caused by diphenylamine, diclofenac and tolfenamic acid. SKF-525A, a general inhibitor of CYP450, markedly inhibited the injury induced by diphenylamine, but not diclofenac or tolfenamic acid. CONCLUSION: The hepatotoxicities caused by diclofenac and tolfenamic acid may be attributed to the mitochondrial dysfunction induced by these drugs instead of the diphenylamine structure per se.

Acta Pharmacol Sin. 2009 May; 30(5): 522-9Fang F, Liu GTAIM: The aim of the present study was to assess the effects of N-[2-(4-hydroxyphenyl)ethyl]-2-(2,5-dimethoxyphenyl)-3-(3-methoxy-4-hydroxyphenyl) acrylamide (compound FLZ), a novel synthetic analogue of squamosamide, on the dysfunction of rat brain mitochondria induced by Abeta(25-35) in vitro. METHODS: Isolated rat brain mitochondria were incubated with aged Abeta(25-35) for 30 min in the presence and absence of FLZ (1-100 micromol/L). The activities of key mitochondrial enzymes, the production of hydrogen peroxide (H(2)O(2)) and superoxide anion (O2*-), and the levels of glutathione (GSH) in mitochondria were examined. Mitochondrial swelling and the release of cytochrome c from mitochondria were assessed by biochemical and Western blot methods, respectively. RESULTS: Incubation of mitochondria with aged Abeta(25-35) inhibited the activities of alpha-ketoglutarate dehydrogenase (alpha-KGDH), pyruvate dehydrogenase (PDH) and respiratory chain complex IV. It also resulted in increased H(2)O(2) and (O2*-) production, and decreased the GSH level in mitochondria. Furthermore, it induced mitochondrial swelling and cytochrome c release from the mitochondria. The addition of FLZ (100 micromol/L) prior to treatment with Abeta(25-35) significantly prevented these toxic effects of Abeta(25-35) on the mitochondria. CONCLUSION: FLZ has a protective effect against Abeta(25-35)-induced mitochondrial dysfunction in vitro.

Planta Med. 2009 May 8; Jiang B, Wu W, Li M, Xu L, Sun K, Yang M, Guan S, Liu X, Guo DAAcute myocardial infarction (AMI) remains the leading cause of mortality in the world. Early intervention using salvianolic acids (SA) can substantially improve clinical outcomes. However, in spite of the great achievements that have been made in elucidating the protective effects of SA on AMI, the effects of SA on the contractile performance of the left ventricle (LV) and the underlying mechanism are still not so clear. In the present study, AMI was introduced by ligation of the left anterior descending coronary artery near the main pulmonary artery. Administration of SA significantly decreased infarct size, improved LV function and appearance of the myocardium and decreased myocardial malondialdehyde levels compared with the AMI group. Furthermore, treatment with SA significantly downregulated the mRNA expression level and activity of matrix metalloproteinase-9 (MMP-9), but did not regulate the tissue inhibitor of metalloproteinase-1 (TIMP-1) expression level at the infarct area. Lisinopril (an angiotensin converting enzyme inhibitor), which holds potential effects on cardioprotection, was chosen as the positive control in this study. Lisinopril elevated LV function and appearance of the myocardium, decreased malondialdehyde levels without an influence on infarct size, and regulated the MMP-9 enzyme level but not the MMP-9 mRNA and TIMP-1 protein levels. These findings suggest that early SA treatment is effective to improve LV function; and SA may exert preventative effects against myocardial remodeling after infarction.