GRP75, defined as a major component of both mitochondrial quality control system and mitochondria-associated membrane, plays a key role in mitochondrial homeostasis. In this study, we assessed the roles of GRP75, other than as a component, in insulin action in both<i> in vitro</i> and <i>in vivo</i> models with insulin resistance. We found that GRP75 was downregulated in HFD-fed mice, and induction of <i>Grp75</i> in mice could prevent HFD induced obesity and insulin resistance. Mechanistically, GRP75 influenced insulin sensitivity by regulating mitochondrial function through its modulation of mitochondrial-supercomplex turnover rather than MAM communication: GRP75 was negatively associated with respiratory-chain complex activity and was essential for mitochondrial-supercomplex assembly and stabilization. Moreover, mitochondrial dysfunction in <i>Grp75</i>-knockdown cells might further increase mitochondrial fragmentation, thus trigger cytosolic mitochondrial DNA release and activate the cGAS/STING-dependent pro-inflammatory response.<b> </b>Therefore, GRP75 can serve as a potential therapeutic target of insulin resistant-related diabetes or other metabolic diseases.
Mutations in FASTKD2, a mitochondrial RNA binding protein, have been associated with mitochondrial encephalomyopathy with isolated complex IV deficiency. However, deficiencies related to other oxidative phosphorylation system (OXPHOS) complexes have not been reported. Here, we identified three novel FASTKD2 mutations, c.808_809insTTTCAGTTTTG, homoplasmic mutation c.868C>T, and heteroplasmic mutation c.1859delT/c.868C>T, in patients with mitochondrial encephalomyopathy. Cell-based complementation assay revealed that these three FASTKD2 mutations were pathogenic. Mitochondrial functional analysis revealed that mutations in FASTKD2 impaired the mitochondrial function in patient-derived lymphocytes due to the deficiency in multi-OXPHOS complexes, whereas mitochondrial complex II remained unaffected. Consistent results were also found in human primary muscle cell and zebrafish with knockdown of FASTKD2. Furthermore, we discovered that FASTKD2 mutation is not inherently associated with epileptic seizures, optic atrophy, and loss of visual function. Alternatively, a patient with FASTKD2 mutation can show sinus tachycardia and hypertrophic cardiomyopathy, which was partially confirmed in zebrafish with knockdown of FASTKD2. In conclusion, both in vivo and in vitro studies suggest that loss of function mutation in FASTKD2 is responsible for multi-OXPHOS complexes deficiency, and FASTKD2-associated mitochondrial disease has a high degree of clinical heterogenicity.
We used a baculovirus expression system to express fusion proteins of HCV core, RGD (Arg-Gly-Asp) peptide, and IFN-α2a fragments in Sf9 cells. Western blotting and electron microscopy demonstrate that HCV core, peptides RGD, and IFN-α2a fusion proteins assemble into 30 to 40 nm nano-particles (virus-like particles, VLPs). Xenograft assays show that VLPs greatly reduced tumor volume and weight with regard to a nontreated xenograft. Migration and invasion results show that VLPs can inhibit the migration and invasion of the breast cancer cells MDA-MB231. This study will provide theoretical and experimental basis for the establishment of safe and effective tumor-targeted drug delivery systems and clinical application of VLPs carrying cell interacting cargo.
Adenine nucleotide translocator 4 (Ant4), an ATP/ADP transporter expressed in the early phases of spermatogenesis, plays a crucial role in male fertility. While Ant4 loss causes early arrest of meiosis and increased apoptosis of spermatogenic cells in male mice, its other potential functions in male fertility remain unexplored. Here, we utilized Ant4 knockout mice to delineate the effects of Ant4-deficiency on male reproduction. Our observations demonstrated that Ant4-deficiency led to infertility and impaired testicular development, which was further investigated by evaluating testicular oxidative stress, autophagy, and inflammation. Specifically, the loss of Ant4 led to an imbalance of oxidation and antioxidants. Significant ultrastructural alterations were identified in the testicular tissues of Ant4-deficient mice, including swelling of mitochondria, loss of cristae, and accumulation of autophagosomes. Our results also showed that autophagic flux and AKT-AMPK-mTOR signaling pathway were affected in Ant4-deficient mice. Moreover, Ant4 loss increased the expression of pro-inflammatory factors. Overall, our findings underscored the importance of Ant4 in regulating oxidative stress, autophagy, and inflammation in testicular tissues. Taken together, these insights provided a nuanced understanding of the significance of Ant4 in testicular development.
Abstract HSP60 is a mitochondrial localized quality control protein responsible for maintaining mitochondrial function. Although HSP60 is considered both a tumor suppressor and promoter in different types of cancer, the role of HSP60 in human pancreatic ductal adenocarcinoma (PDAC) remains unknown. In this study, we demonstrated that HSP60 was aberrantly expressed in human pancreatic cancer tissues and cell lines. Analysis of the Cancer Genome Atlas database revealed that HSP60 expression is positively correlated with pancreatic cancer. Further, knockdown of HSP60 attenuated pancreatic ductal cancer cell proliferation and migration/invasion, whereas ectopic expression of HSP60 increased tumorigenesis. Using an in vivo tumorigenicity assay, we confirmed that HSP60 promoted the growth of pancreatic ductal cancer cells. Functional analyses demonstrated that HSP60 plays a key role in the regulation of mitochondrial function. Mechanistically, both HSP60 knockdown and oxidative phosphorylation (OXPHOS) inhibition by metformin decreased Erk1/2 phosphorylation and induced apoptosis and cell cycle arrest, whereas Erk1/2 reactivation with EGF promoted cell proliferation. Intriguingly, in vitro ATP supplementation partially restored Erk1/2 phosphorylation and promoted proliferation in PDAC cells with HSP60 knockdown and OXPHOS inhibition. These results suggest that mitochondrial ATP is an important sensor of Erk1/2 regulated apoptosis and the cell cycle in PDAC cells. Thus, our findings indicate for the first time that HSP60 may serve as a novel diagnostic target of human pancreatic cancer, and that inhibition of mitochondrial function using drugs such as metformin may be a beneficial therapeutic strategy targeting pancreatic cancer cells with aberrant function of the HSP60/OXPHOS/Erk1/2 phosphorylation axis.
Studies have shown that miR-221 and miR-222 are deregulated in many cancers, including prostate cancer. Nevertheless, the biological role and the underlying mechanisms of miR-221 and miR-222 in the pathogenesis of androgen-independent prostate cancer are still not clear. The proliferation, apoptosis, cell cycle distinction, and migration capacity of prostate cells were determined following transfection of miR-221 or miR-222 inhibitor. The biological impact and regulation of SIRT1 on prostate cancer cells were investigated. MiR-221 and miR-222 were highly expressed in PC-3 cells compared with in LNCap cells. After miR-221 or miR-222 expression was inhibited, the proliferation and migration rates of PC-3 cells decreased and the apoptosis rate increased. Moreover, SIRT1 protein was up-regulated in cells after they were transfected with miR-221 or miR-222 inhibitor. Cells transfected with siSIRT1 showed increased migration and a decreased apoptosis rate, but there was no significant effect on cell proliferation compared with the controls. There was a negative correlation between miR-221 or miR-222 and SIRT1, but no direct target relationship was identified. These data demonstrate that miR-221 and miR-222 are highly expressed in PC-3 cells. Their inhibition leads to reduced cell proliferation and migration and increased apoptosis in prostate cancer cells. These effects are potentially mediated by up-regulation of SIRT1.
Interleukin-4 (IL-4) plays an important role in the pathogenesis of cancer. The −590C/T polymorphism in the IL-4 gene has been implicated in susceptibility to cancer, but the results have been inconclusive. The aim of this study was to analyze the association between this polymorphism with the risk of cancer by meta-analysis. PubMed, Embase, CNKI, and Wanfang databases were searched for all publications concerning the association between this polymorphism and cancer risk. Statistical analyses were analyzed by using RevMan 4.2 and STATA10.0 softwares. A total of 8,715 cases and 9,532 controls in 23 case–control studies were included. The results suggested that there was no significant association between IL-4 −590C/T polymorphism and cancer risks (TT + TC vs. CC: OR = 0.97, 95 % CI = 0.90–1.04, P = 0.36). In the subgroup analysis by ethnicity, no significant association was detected in Asians and Caucasians. In the subgroup analysis by cancer types, no significant association was found in gastric cancer and colorectal cancer. The current meta-analysis suggested that the −590C/T polymorphism in the IL-4 gene might not be associated with increased/decreased risk of cancer. The −590C/T polymorphism might be not a risk factor for cancers.
Abstract The development of novel methods for highly efficient protein purification remains a research focus in the biotechnology field because conventional purification approaches, including affinity purification, gel filtration, and ion-exchange chromatography, require complex manipulation steps and are costly. Here, we describe a simple and rapid protein purification strategy in which the SUMO tag and Ulp1 protease are surface-displayed separately on Escherichia coli cells. After protein induction, the cells are harvested, resuspended in cleavage buffer, and incubated together for cleavage. In this approach, the surface-displayed Ulp1 cleaves the membrane-anchored SUMO fusion protein, resulting in the release of the target protein from the C-terminal of SUMO into the solution. The bacterial cells harboring SUMO and Ulp1 on their surfaces can be easily removed by centrifugation. To evaluate the purification method, we used red fluorescent protein (mCherry). Purified mCherry protein (7.72 ± 1.05 mg from 1 L of bacterial culture) was obtained after only 30 min of incubation. The protein purity was higher than 80%, and could be further improved (> 90%) by simple ultrafiltration. This study offers a promising and simple strategy for the purification of recombinant protein in its native form that requires only cleavage and centrifugation steps.
GRP75 (75-kDA glucose-regulated protein), defined as a major component of both the mitochondrial quality control system and mitochondria-associated membrane, plays a key role in mitochondrial homeostasis. In this study, we assessed the roles of GRP75, other than as a component, in insulin action in both in vitro and in vivo models with insulin resistance. We found that GRP75 was downregulated in mice fed a high-fat diet (HFD) and that induction of Grp75 in mice could prevent HFD-induced obesity and insulin resistance. Mechanistically, GRP75 influenced insulin sensitivity by regulating mitochondrial function through its modulation of mitochondrial-supercomplex turnover rather than mitochondria-associated membrane communication: GRP75 was negatively associated with respiratory chain complex activity and was essential for mitochondrial-supercomplex assembly and stabilization. Moreover, mitochondrial dysfunction in Grp75-knockdown cells might further increase mitochondrial fragmentation, thus triggering cytosolic mtDNA release and activating the cGAS/STING-dependent proinflammatory response. Therefore, GRP75 can serve as a potential therapeutic target of insulin resistant-related diabetes or other metabolic diseases.
To investigate the expression of Survivin in patients with extrahepatic cholangiocarcinoma (EHCC) and its relationship with clinicopathological features of EHCC, and the correlation between the expression of Survivin and lymph node micrometastasis, tumor markers, and the prognosis of EHCC.The expression of Survivin protein in paraffin-embedded specimens of 59 patients with EHCC and their 20 para-carcinoma tissues were evaluated by S-P method of immunohistochemical staining. The correlation between the expression of Survivin and the lymph node micrometastasis, clinicopathological features of EHCC and the prognosis of EHCC were analyzed.The positive expression rate of Survivin protein was 67.8% (40/59) in paraffin-embedded specimens of 59 patients with EHCC and was 20.0% (4/20) in para-carcinoma tissues, and difference between carcinoma tissues and para-carcinoma tissues was significant (P<0.01). Histological differentiation in EHCC had a negative correlation with the expression of Survivin protein, while the expression of Survivin protein in EHCC had a positive correlation with TNM of EHCC, lymphatic vessel infiltration, lymph node metastasis and perineural invasion (P<0.05). The serum CA19-9 levels in the positive group with expression of Survivin protein was (290,300+/-55 500) U/L and was obviously higher than that in the negative group [(113,300+/-31,400) U/L, P<0.05]. The mean survival time of the patients with negative expression of Survivin protein was higher than that of the patients with positive expression (43.5 vs. 21.1 months, P<0.01). Screened to significance univariate, the multivariate analysis through Cox proportional hazard model analysis showed that lymph node metastasis, residual tumor margins, and expression of Survivin protein were independent prognosis factors of the patients with EHCC (P<0.05, P<0.01, P<0.01).The expression of Survivin protein in EHCC has a negative correlation with histological differentiation, while has a positive correlation with lymphatic vessel infiltration and serum CA19-9 concentrations. The expression of Survivin protein maybe an independent prognosis factor of the patients with EHCC.
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