Objective Investigation of biological characteristics of Cdc 20AAA/+APCmin/+ mouse embryonic fibroblast(MEFs) indicate the effect of Cdc20AAA/+on growth of mouse embryonic fibroblast and the possible mechanism . Methods MEFs of Cdc20AAA/+APCmin/+, Cdc20AAA/+, APCmin/+ and WT genotype were harvested from embryos for analysis.The growth characteristics of Cdc20AAA/+APCmin/+, Cdc20AAA/+,APCmin/+and WT mouse embryonic fibroblast were analyzed through growth curve analysis and foci formation assay .Separation of sister chromatid and the presence of aneuploid were detected by karyotype analysis .Results Cell proliferation assays showed that Cdc 20AAA/+APCmin/+cells grew at an accelerated rate compared with APC min/+MEFs(P<0.01).Foci formation assay showed that the clone forming ability was significantly increased .Cdc20AAA/+APCmin/+MEFs showed a significant increase in the frequency of aneuploid compared with WT MEFs , which had a karyotype of 38 and contained prematurely separated sister chromatids .Conclusion Cdc20 carrying a null allele (Cdc20AAA/+) may accelerate the growth and proliferation of APC min/+MEFs and present the growth characteristics of the tumor cells .The possible mechanism may be associated with chromosome instability .

Background::Parkinson’s disease (PD) is the second most common neurodegenerative disease after Alzheimer’s dementia. Mitochondrial dysfunction is involved in the pathology of PD. Coiled-coil-helix-coiled-coil-helix domain-containing 2 (CHCHD2) was identified as associated with autosomal dominant PD. However, the mechanism of CHCHD2 in PD remains unclear.Methods::Short hairpin RNA (ShRNA)-mediated CHCHD2 knockdown or lentivirus-mediated CHCHD2 overexpression was performed to investigate the impact of CHCHD2 on mitochondrial morphology and function in neuronal tumor cell lines represented with human neuroblastoma (SHSY5Y) and HeLa cells. Blue-native polyacrylamide gel electrophoresis (PAGE) and two-dimensional sodium dodecyl sulfate-PAGE analysis were used to illustrate the role of CHCHD2 in mitochondrial contact site and cristae organizing system (MICOS). Co-immunoprecipitation and immunoblotting were used to address the interaction between CHCHD2 and Mic10. Serotype injection of adeno-associated vector-mediated CHCHD2 and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration were used to examine the influence of CHCHD2 in vivo.Results::We found that the overexpression of CHCHD2 can protect against methyl-4-phenylpyridinium (MPP+)-induced mitochondrial dysfunction and inhibit the loss of dopaminergic neurons in the MPTP-induced mouse model. Furthermore, we identified that CHCHD2 interacted with Mic10, and overexpression of CHCHD2 can protect against MPP +-induced MICOS impairment, while knockdown of CHCHD2 impaired the stability of MICOS. Conclusion::This study indicated that CHCHD2 could interact with Mic10 and maintain the stability of the MICOS complex, which contributes to protecting mitochondrial function in PD.

Previous studies suggest that the reduction of SMAD3 (mothers against decapentaplegic homolog 3) has a great impact on tumor development, but its exact pathological function remains unclear. In this study, we found that the protein level of SMAD3 was greatly reduced in human-grade IV glioblastoma tissues, in which LAMP2A (lysosome-associated membrane protein type 2A) was significantly up-regulated. LAMP2A is a key rate-limiting protein of chaperone-mediated autophagy (CMA), a lysosome pathway of protein degradation that is activated in glioma. We carefully analyzed the amino-acid sequence of SMAD3 and found that it contained a pentapeptide motif biochemically related to KFERQ, which has been proposed to be a targeting sequence for CMA. In vitro, we confirmed that SMAD3 was degraded in either serum-free or KFERQ motif deleted condition, which was regulated by LAMP2A and interacted with HSC70 (heat shock cognate 71 kDa protein). Using isolated lysosomes, amino-acid residues 75 and 128 of SMAD3 were found to be of importance for this process, which affected the CMA pathway in which SMAD3 was involved. Similarly, down-regulating SMAD3 or up-regulating LAMP2A in cultured glioma cells enhanced their proliferation and invasion. Taken together, these results suggest that excessive activation of CMA regulates glioma cell growth by promoting the degradation of SMAD3. Therefore, targeting the SMAD3-LAMP2A-mediated CMA-lysosome pathway may be a promising approach in anti-cancer therapy.