Paradoxical Mitophagy Regulation by PINK1 and TUFm.

Aberrant mitophagy has been implicated in a broad spectrum of disorders. PINK1, Parkin, and ubiquitin have pivotal roles in priming mitophagy. However, the entire regulatory landscape and the precise control mechanisms of mitophagy remain to be elucidated. Here, we uncover fundamental mitophagy regulation involving PINK1 and a non-canonical role of the mitochondrial Tu translation elongation factor (TUFm). The mitochondrion-cytosol dual-localized TUFm interacts with PINK1 biochemically and genetically, which is an evolutionarily conserved Parkin-independent route toward mitophagy. A PINK1-dependent TUFm phosphoswitch at Ser222 determines conversion from activating to suppressing mitophagy. PINK1 modulates differential translocation of TUFm because p-S222-TUFm is restricted predominantly to the cytosol, where it inhibits mitophagy by impeding Atg5-Atg12 formation. The self-antagonizing feature of PINK1/TUFm is critical for the robustness of mitophagy regulation, achieved by the unique kinetic parameters of p-S222-TUFm, p-S65-ubiquitin, and their common kinase PINK1. Our findings provide new mechanistic insights into mitophagy and mitophagy-associated disorders.

Pectic polysaccharides extracted from Rauvolfia verticillata (Lour.) Baill. var. hainanensis Tsiang ameliorate ulcerative colitis via regulating the MAPKs and NF-κB pathways in dendritic cells.

This study was to investigate the effects and mechanisms of pectic polysaccharides (PP) extracted from Rauvolfia verticillata (Lour.) Baill. var. hainanensis Tsiang on dextran sulphate sodium (DSS)-induced ulcerative colitis (UC). Eighty female BALB/c mice were randomly divided into four groups: Control, DSS, DSS + salicylazosulfapyridine (SASP), and DSS+ PP. The disease activity index (DAI), overall physical activity, and blood stool were monitored daily to evaluate severity of UC. Histological scores of the colon were observed. The expression of nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPKs) pathways in colon tissues and bone marrow-derived dendritic cells (DCs) was assessed by western blot, immunohistochemistry, electrophoretic mobility shift assay (EMSA) and real time polymerase chain reaction (RT-PCR). Cytokines were measured by enzyme-linked immunosorbent assay (ELISA). The overall physical activity, DAI and histological scores decreased in DSS+SASP and DSS+PP groups, compared with the DSS-alone group. Also, tumour necrosis factor α (TNF-α) and interleukin 6 (IL-6) reduced significantly while the expression of IκBα was up-regulated, extracellular signal-regulated kinase (ERK), Jun N-terminal kinase (JNK) and p38 were activated, in DSS+SASP and DSS+PP groups. PP inhibited activation of MAPKs and NF-κB pathways in the bone-marrow-derived DCs. In conclusion, PP significantly ameliorated murine DSS-induced UC model, via regulation of MAPKs and NF-κB pathways in DCs.

Phosphatidylinositol 3,4-bisphosphate regulates neurite initiation and dendrite morphogenesis via actin aggregation.

Neurite initiation is critical for neuronal morphogenesis and early neural circuit development. Recent studies showed that local actin aggregation underneath the cell membrane determined the site of neurite initiation. An immediately arising question is what signaling mechanism initiated actin aggregation. Here we demonstrate that local clustering of phosphatidylinositol 3,4-bisphosphate (PI(3,4)P2), a phospholipid with relatively few known signaling functions, is necessary and sufficient for aggregating actin and promoting neuritogenesis. In contrast, the related and more extensively studied phosphatidylinositol 4,5-bisphosphate or phosphatidylinositol (3,4,5)-trisphosphate (PIP3) molecules did not have such functions. Specifically, we showed that beads coated with PI(3,4)P2 promoted actin aggregation and neurite initiation, while pharmacological interference with PI(3,4)P2 synthesis inhibited both processes. PI(3,4)P2 clustering occurred even when actin aggregation was pharmacologically blocked, demonstrating that PI(3,4)P2 functioned as the upstream signaling molecule. Two enzymes critical for PI(3,4)P2 generation, namely, SH2 domain-containing inositol 5-phosphatase and class II phosphoinositide 3-kinase α, were complementarily and non-redundantly required for actin aggregation and neuritogenesis, as well as for subsequent dendritogenesis. Finally, we demonstrate that neural Wiskott-Aldrich syndrome protein and the Arp2/3 complex functioned downstream of PI(3,4)P2 to mediate neuritogenesis and dendritogenesis. Together, our results identify PI(3,4)P2 as an important signaling molecule during early development and demonstrate its critical role in regulating actin aggregation and neuritogenesis.

Experiment research of cisplatin implants inhibiting transplantation tumor growth and regulating the expression of KLK7 and E-cad of tumor-bearing mice with gastric cancer.

OBJECTIVE: To study the influence of cisplatin implants on transplantation tumor growth and the expression of tissue kallikrein-7 (KLK7) and E-cadherin (E-cad) in tumor-bearing mice with gastric cancer. METHODS: BALB/c nude mice were collected as experimental animal and were randomly divided into model control group (Group A), tail intravenous injection of cisplatin group (Group B), intratumor injection of cisplatin group (Group C) and cisplatin implants treatment group (Group D). After the drugs intervening, the weight and volume of transplantation tumors were measured on Day 20, Day 30 and Day 40 and serum and KLK7 and E-cad contents in transplanted tumor tissue were examined. RESULTS: On Day 20, Day 30 and Day 40 after treatment, the weight and volume of transplantation tumors of tumor-bearing mice in four groups were different (Group A > Group B > Group C > Group D). The contents of KLK-7 and E-cad in tumor tissue and serum of tumor-bearing mice in four groups were different (Group A > Group B > Group C > Group D in KLK-7) and (Group A < Group B < Group C < Group D in E-cad). The weight and volume, and KLK7 and E-cad contents of transplantation tumors in four groups were significant difference (P < 0.05). CONCLUSION: Cisplatin implants can inhibit the growth of transplanted tumor tissue and down-regulated KLK7 expression and up-regulated E-cad expression of tumor-bearing mice with gastric cancer.

Expression of serum Dickkopf-1 in gastric cancer patients.

OBJECTIVE: To explore the expression and clinical significance of DKK-1 protein in patients with gastric cancers. METHODS: Enzyme linked immuno sorbent assay was used to detect expressions of serum DKK-1 protein in 90 cases of gastric cancers, 50 cases of gastric benign disease and 40 healthy cases. The dynamic change in serum DKK-1 protein of gastric cancer patients who accepted radical operation for a month was also observed. RESULTS: The expression of serum DKK-1 protein in gastric cancer groups was significantly higher than that in gastric benign group's (P < 0.01) and in health control (P < 0.01). Serum DKK-1 level was increased gradually along with the progress of the disease. Serum DKK-1 levels were significantly higher in patients at TNM staging III and IV than patients at TNM staging I and II. Level of serum DKK-1 was related to microvascular invasion, differentiation degree and infiltration depth. Level of serum DKK-1 was significantly reduced in patients after radical surgery (P < 0.01). CONCLUSIONS: The expression of serum DKK-1 protein in gastric cancer patients is increased. Level of serum DKK-1 is related to TNM staging, microvascular invasion, differentiation degree and infiltration depth. DKK-1 detection can be used as a reference index in monitoring gastric cancer progress and biological behavior.

Suppressive effect of pectic polysaccharides extracted from Rauwolfia verticillata (Lour.) Baill.var.hainanensis Tsiang on inflammation by regulation of NF- κ B pathway and interleukin-17 in mice with dextran sulphatesodium-induced ulcerative colitis.

OBJECTIVE: To investigate the effects of pectic polysaccharides extracted from Rauwolfia verticillata (Lour.) Baill.var.hainanensis Tsiang on an experimental murine colitis model. METHODS: Experimental colitis was induced by dextran sulfate sodium (DSS), and mice were divided into 4 groups: control, DSS alone, DSS plus SASP, DSS plus pectic polysaccharides. The disease activity index (DAI) and histological score were observed. The tumor necrosis factor (TNF)- α and interleukin (IL)-17 levels were measured by enzyme-linked immunosorbent assay. I κ B and NF- κ B p65 expression were assessed by western blot analysis. Myeloperoxidase (MPO) activity was determined by using MPO assay kit. RESULTS: Administration of pectic polysaccharides significantly reduced the severity of DSS-induced colitis as assessed by DAI and histological score, and resulted in down regulation of MPO activity and NF- κ B p65 expression and subsequent degradation of I κ B protein, strikingly reduced the production of TNF- a and IL-17. CONCLUSIONS: Pectic polysaccharides extracted from Rauvolfia verticillata (Lour.)Baill.var. hainanensis Tsiang exerts beneficial effects in experimental colitis and may therefore provide a useful therapeutic approach for the treatment of UC.