Is the mitochondrion a promising drug target in trypanosomatids?

The trypanosomatids Trypanosoma brucei, Trypanosoma cruzi and Leishmania spp. are etiological agents of important neglected tropical diseases, affecting millions of people worldwide, and the drugs available for these diseases present several limitations. Novel efficient and nontoxic drugs are necessary as an alternative to the current chemotherapy. The unique mitochondrion of trypanosomatids and its peculiar features turn this organelle a potential drug target. Several phenotypic studies describe the damage in the parasite mitochondrial ultrastructure, but the molecular target is unknown. Few reports demonstrated the electron transport system (ETS) as a target due to the high similarities to mammalian orthologues, hence ETS is not a good candidate for drug intervention. On the other hand, antioxidant enzymes, such as trypanothione reductase, and an alternative oxidase (AOX) seem to be interesting targets; however no high active inhibitors were developed up to now. Finally, due to the remarkable differences to mammalian machinery, together with the high biological importance for the parasite survival, the mitochondrial import system stands out as a very promising target in trypanosomatids. Archaic translocase of the outer membrane (ATOM) and translocase of the inner membrane (TIM) complexes, which mediate both protein and tRNA import, composed by specific subunits of these parasites, could be excellent candidates, deserving studies focused on the development of specific drugs.

Role of OMA1 in lipopolysaccharide-induced acute kidney injury / 中华肾脏病杂志

Objective To investigate the role of OMA1 in acute kidney injury (AKI) induced by lipopolysaccharide (LPS).Methods OMA1 wild-type and knocked out mice (8 week old) were injected with 10 mg/kg body weight of LPS.The model was confirmed by testing mouse serum creatinine and blood urea nitrogen.The apoptosis in mouse kidney cortex was examined by TUNEL staining and cleaved caspase 3.In vitro,in humam kidney proximal tubular cells (HK2) were knocked down OMA1 by transfecting OMA1 shRNA,with the scramble shRNA being used as negative control of transfection.HK2 cells were cultured with 5 μg/ml of LPS for 24 hours to induce apoptosis.DAPI staining of cells and caspase-3 activity were applied to test apoptosis.The images of mitochondria in cells were obtained by transfection of mito-green plasmid and OMA1 shRNA.Western blotting was used to exam the OMA1 and Cytochrome C expressions.Resudts Compared with OMA1 KO mice,LPS induced more severe AKI of WT mice with higher Scr [(97.2±26.5) μmol/L vs (53.0±17.7) μmol/L,P ＜ 0.05] and BUN [(43.3± 13.7) mmol/L vs (29.7±7.7) mmol/L,P ＜ 0.05].Moreover,there were more apoptosis cells in kidney cortex in WT mice than in OMA1 KO mice [(75.4± 26.1)/ram2 vs (38.3± 14.4)/mm2,P＜ 0.05].About 46％ of OMA1 expressions in HK2 cells were inhibited by OMA1 shRNA transfection (P ＜ 0.05).Further,OMA1 shRNA cells with LPS stimulation had decreased mitochondria fragmentation [(29.8±10.9)％ vs (43.2±6.8)％,P ＜ 0.05],Cytochrome C release [(37.0±12.3)％ vs (76.0±26.2)％,P ＜ 0.05],and cell apoptosis [(13.2±3.9)％ vs (25.0±7.1)％,P ＜ 0.05] as compared with control cells.Conclusion Knockdown of OMA1 alleviated septic AKI through inhibition of cell apoptosis,mitochondria fragmentation,and Cytochrome C release.

Effect of Ovariectomy and Genistein on Hepatic Mitochondrial Function

Women with menopause or rats with ovariectomy is associated with increased body weight, body fat and insulin resistance, which are components of metabolic syndrome. Increased prevalence of metabolic syndrome after menopause might be associated with mitochondrial dysfunction, since mitochondrial oxidative and phosphorylation activity is strongly correlated with insulin sensitivity. Although estradiol replacement prevents the metabolic syndrome, harmful effect of estradiol hampers the casual usage to prevent the metabolic syndrome. It has been reported that genistein has a mild estrogenic activity, decreases fat mass in mice and has an antidiabetic role in diabetic rats. Although insulin resistance is closely related to mitochondrial functions, there has not been yet any study in regard to the effect of dietary genistein on mitochondrial function in the insulin resistant female subjects induced by ovariectomy or similar situation. The present study investigated whether the supplementation of genistein in the high fat diet affected the mitochondrial function of high fat fed ovariectomized rats. Female Sprague Dawley rats (8 weeks old) were assigned to the following groups: sham-operated + high fat diet (S, n = 6); sham-operated + high fat diet with 0.1% genistein (S + G, n = 7); ovariectomized + high fat diet (OVX, n = 8); ovariectomized + high fat diet with 0.1% genistein (OVX + G, n = 8). Ovariectomy significantly increased body weight compared with S group. Genistein consumption in ovariectomized (OVX + G) rats decreased body weight gain compared with OVX rats. Liver weights were increased by ovariectomy. The hepatic mitochondrial protein density expressed as mg per g liver was lower in the OVX group than in the S group. However, OVX + G group showed the increased mitochondrial protein density similar to the level of S group. When mRNA levels of genes related to mitochondria such as peroxisome proliferator-activated receptor gamma coactivator 1 (PGC-1) and cytochrome c oxidase subunit III (COX III) were measured, there were decreases in the mRNA levels of PGC-1 and COX III in S + G, OVX and OVX + G group. The activity of cytochrome c oxidase was not different between groups. We could observe the decrease in succinate dehydrogenase (SDH) activity per g liver in OVX rats. Genistein supplement increased SDH activity. In conclusion, genistein supplementation to the OVX rats enhanced mitochondrial function by increasing mitochondrial protein density and SDH activity. The improvement in mitochondrial function by genistein can contribute to the improvement in metabolic syndrome.

Inhibitory effects of tumor associated mitochondrial protein 12 on HepG2 cell apoptosis / 中国病理生理杂志

AIM:To explore the inhibitory effects of tumor associated mitochondrial protein 12 (TAMP12) on tumor cell apoptosis. METHODS: (1) A retrovirus expression vector was recombinated and transfected into the packaging cell line PA317. The virus particles were obtained to infect the target cell line HepG2 low expressing of TAMP12. The expression of TAMP12 mRNA was detected by RT-PCR. The subcellular localization and quantification of TAMP12 protein labeled with double fluorescein were observed under confocal laser scanning microscope (CLSM). (2) Hoechst33258 staining and flow cytometry (FACS) were used to analysis the apoptosis of HepG2 cells treated with 5-fluorouracil (5-FU). RESULTS: (1) The CLSM observation showed that TAMP12 protein was mainly expressed in mitochondria of HepG2 cells. The expressions of TAMP12 gene and protein were stable and high in transfected HepG2 cells. (2) Upon treatment with 5-FU, the transfected HepG2 cells showed a fairly integrated nucelus while the control HepG2 cells exhibited chromatin condensation, marginalization and karyorhexix. Moreover, the apoptosis rate of transfeced HepG2 cells was significantly lower than that in control HepG2 cells (P