Volume 401, Issue 3

Succinate dehydrogenase (SDH), complex II or succinate:quinone oxidoreductase (SQR) is a crucial enzyme involved in both the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS), the two primary metabolic pathways for generating ATP. Impaired function of SDH results in deleterious disorders from cancer to neurodegeneration. SDH function is tailored to meet the energy demands in different cell types. Thus, understanding how SDH function is regulated and how it operates in distinct cell types can support the development of therapeutic approaches against the diseases. In this article we discuss the molecular pathways which regulate SDH function and describe extra roles played by SDH in specific cell types.

Tuberculosis caused by Mycobacterium tuberculosis remains a serious threat to public health. The M. tuberculosis cell envelope is closely related to its virulence and drug resistance. Mycobacterial membrane large proteins (MmpL) are lipid-transporting proteins of the efflux pump resistance nodulation cell division (RND) superfamily with lipid substrate specificity and non-transport lipid function. Mycobacterial membrane small proteins (MmpS) are small regulatory proteins, and they are also responsible for some virulence-related effects as accessory proteins of MmpL. The MmpL transporters are the candidate targets for the development of anti-tuberculosis drugs. This article summarizes the structure, function, phylogenetics of M. tuberculosis MmpL/S proteins and their roles in host immune response, inhibitors and regulatory system.

Angiogenesis is believed to protect against hypoxia/reoxygenation (H/R)-induced cell injury. MALAT1 and microRNA-320a (miR-320a) are involved in cancer angiogenesis. To investigate the function of the MALAT1/miR-320a axis in H/R-induced cell injury, human umbilical vein endothelial cell (HUVEC) angiogenesis was detected using the Cell Counting Kit-8 (CCK-8), Transwell migration, cell adhesion and tube formation assays. The expression of MALAT1 and miR-320a was revealed by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The direct binding relationship between miR-320a and MALAT1 was detected by RNA immunoprecipitation (RIP) and dual luciferase reporter assays. The data indicated that H/R induces angiogenesis injury and that the expression of MALAT1 was augmented in H/R-stimulated HUVECs. Overexpression of MALAT1 alleviated H/R-stimulated HUVEC dysfunction, whereas silencing of MALAT1 exerted the opposite effects. MALAT1 also reduced miR-320a levels in HUVECs. Overexpression of miR-320a repressed the function of MALAT1 on H/R-stimulated HUVECs, whereas inhibition of miR-320a exerted the opposite effect. Additionally, miR-320a inhibition alleviated H/R-stimulated HUVEC injury via RAC1. Taken together, this investigation concluded that MALAT1 represses H/R-stimulated HUVEC injury by targeting the miR-320a/RAC1 axis.

CYP20A1 is a well-conserved member of the human cytochrome P450 enzyme family for which no endogenous or xenobiotic substrate is known. We have recently shown that this enzyme has moderate activity towards two proluciferin probe substrates. In order to facilitate the search for physiological substrates we have tested nine additional proluciferins in this study and identified three such probe substrates that give much higher product yields. Using one of these probes, we demonstrate inhibition of CYP20A1 activity by 1-benzylimidazole, ketoconazole and letrozole. Finally, we show that the combination of two common single nucleotide polymorphisms (SNPs) of CYP20A1 leads to an enzyme (CYP20A1 Leu97Phe346 ) with reduced activity.

The objective of this study was to reveal a novel mechanism underlying the progression of atherosclerosis (AS) associated with endothelial cells (ECs) and neutrophils. Transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA) were used to observe the morphology and particle size of isolated exosomes. Western blotting was applied to examine exosomal markers, while the expression of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) was measured by quantitative real-time polymerase chain reaction (qRT-PCR). The production of inflammatory cytokines and reactive oxygen species (ROS) was determined by an enzyme-linked immunosorbent assay (ELISA) and a dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay. Circulating neutrophil extracellular traps (NETs) were represented by myeloperoxidase (MPO)-DNA complexes. NETs formation was assessed using immunofluorescence microscopy. Atherosclerotic lesion development was measured by Oil Red O (ORO) staining. In the results, MALAT1 expression was increased in exosomes extracted from oxidized low-density lipoprotein (ox-LDL)-treated human umbilical vein endothelial cells (HUVECs). When co-cultured with human neutrophils, exosomes derived from ox-LDL-treated HUVECs were revealed to promote NETs formation, which was mediated by exosomal MALAT1. Furthermore, ox-LDL-treated HUVECs-derived exosomes were demonstrated to trigger hyperlipidemia, inflammatory response and NETs release in a mouse model of AS. In conclusion, exosomal MALAT1 derived from ox-LDL-treated ECs initiated NETs formation, which in turn deteriorated AS.

Breast cancer is one of the most common malignant tumors in women. Derlin-1 has been found to be overexpressed in several human cancers in addition to playing an important role in tumor processes; however, the expression patterns and functions of Derlin-1 in human breast cancer are not fully understood. In this study, we found that Derlin-1 overexpression was higher in breast cancer compared to normal samples through TCGA and GTEx database analyses. Kaplan-Meier plotter analysis showed that Derlin-1 was a predicting factor for patient prognosis. Derlin-1 expression was significantly up-regulated in breast cancer tissues (18/30, 60.00%) compared to corresponding paracancerous tissue (9/30, 30.00%, p  < 0.05) as detected by immunohistochemistry, and the expression of Derlin-1 was correlated to pathological grading. siRNA interference of Derlin-1 inhibited cell proliferation, which is associated with the promotion of apoptosis and migration. Derlin-1 knockdown suppressed the protein levels of p-AKT and Cyclin D1 while up-regulating Caspase3 and Bax. GEPIA database analysis showed that MTDH and ATAD2 were downstream target genes, and the expression of MTDH and was suppressed in Derlin-1 knockdown cells. Taken together, our results demonstrated ATAD2 that Derlin-1 is overexpressed in breast cancer and promoted a malignant phenotype through the AKT signaling pathway.

Various pathophysiological situations of negative energy balance involve the intense depletion of the body’s energy reserves. White adipose tissue is a central place to store energy and a major endocrine organ. As a model of choice to better understand how the white adipose tissue dynamically responds to changes in substrate availability, we used the prolonged fasting paradigm, which is characterized by successive periods of stimulated (phase 2) and then reduced (phase 3) lipid mobilization/utilization. Using omics analyses, we report a regulatory transcriptional program in rat epididymal (EPI) adipose tissue favoring lipolysis during phase 2 and repressing it during phase 3. Changes in gene expression levels of lipases, lipid droplet-associated factors, and the proteins involved in cAMP-dependent and cAMP-independent regulation of lipolysis are highlighted. The mRNA and circulating levels of adipose-secreted factors were consistent with the repression of insulin signaling during prolonged fasting. Other molecular responses are discussed, including the regulation of leptin and adiponectin levels, the specific changes reflecting an increased fibrinolysis and a possible protein catabolism-related energy saving mechanism in late fasting. Finally, some differences between internal and subcutaneous (SC) adipose tissues are also reported. These data provide a comprehensive molecular basis of adipose tissue responses when facing a major energetic challenge.

Long noncoding RNA 01296 (Lnc01296) is dysregulated in malignant tumors. However, the detailed effect of Linc01296 on hepatocellular carcinoma (HCC) remains largely unknown. In this study, we identified the biological role of Linc01296 in HCC. The levels of Linc01296 in HCC tissues and a panel of cell lines were assessed by quantitative real-time polymerase chain reaction (qRT-PCR). The effects of Linc01296 on HCC progression were explored using a Cell Counting Kit-8 (CCK-8), flow cytometry, migration and Transwell invasion assays. The interactions among Linc01296, miR-26a and PTEN were determined using luciferase, RNA immunoprecipitation (RIP) and Western blot assays. Tumor xenograft models were utilized to confirm the in vivo functional roles of Linc01296 in HCC development. Linc01296 expression was increased in both HCC tissue samples and cell lines. Knockdown of Linc01296 suppressed HCC cell processes, such as proliferation, migration and invasion, and enhanced apoptosis in vitro ; these effects were reversed by a miR-26a mimic or PTEN overexpression. Furthermore, knockdown of Linc01296 suppressed HCC growth in vivo. These findings indicated that Linc01296 is involved in HCC progression via regulating miR-26a/PTEN.

Circulating CD44 + cells have been identified as a prognostic marker for patients with non-small cell lung cancer (NSCLC). Serum tumor necrosis factor-related apoptosis-inducing ligand (sTRAIL) is involved in the pathophysiology of many cancers. However, no previous studies have shown the roles of sTRAIL in circulating CD44 + cells in the blood of NSCLC patients. We detected circulating CD44 + cells and sTRAIL levels in blood samples from NSCLC patients using flow cytometry and an enzyme-linked immunosorbent assay (ELISA). Anti-tumor roles of TRAIL in CD44 + cells were confirmed using a CCK-8 assay and mouse models. A higher number of circulating CD44 + cells were identified in NSCLC patients compared with healthy control individuals. In addition, we confirmed the anti-tumor roles and mechanisms of TRAIL in CD44 + cells both in vitro and in vivo . Our results indicate that (1) there is a negative correlation between sTRAIL and circulating CD44 + cells in NSCLC patients and (2) CD44 + cells have cancer stem cell properties and are more sensitive than CD44 − cells to TRAIL.