Mlig-SKP1 Gene Is Required for Spermatogenesis in the Flatworm Macrostomum lignano

In a free-living flatworm, Macrostomum lignano, an S-phase kinase-associated protein 1 (SKP1) homologous gene was identified as enriched in proliferating cells, suggesting that it can function in the regulation of stem cells or germline cells since these are the only two types of proliferating cells in flatworms. SKP1 is a conserved protein that plays a role in ubiquitination processes as a part of the Skp1-Cullin 1-F-box (SCF) ubiquitin ligase complex. However, the exact role of Mlig-SKP1 in M. lignano was not established. Here, we demonstrate that Mlig-SKP1 is neither involved in stem cell regulation during homeostasis, nor in regeneration, but is required for spermatogenesis. Mlig-SKP1(RNAi) animals have increased testes size and decreased fertility as a result of the aberrant maturation of sperm cells. Our findings reinforce the role of ubiquitination pathways in germ cell regulation and demonstrate the conserved role of SKP1 in spermatogenesis.     

Stearoyl CoA Desaturase-1 Silencing in Glioblastoma Cells: Phospholipid Remodeling and Cytotoxicity Enhanced upon Autophagy Inhibition

Modulation of lipid metabolism is a well-established cancer hallmark, and SCD1 has been recognized as a key enzyme in promoting cancer cell growth, including in glioblastoma (GBM), the deadliest brain tumor and a paradigm of cancer resistance. The central goal of this work was to identify, by MS, the phospholipidome alterations resulting from the silencing of SCD1 in human GBM cells, in order to implement an innovative therapy to fight GBM cell resistance. With this purpose, RNAi technology was employed, and low serum-containing medium was used to mimic nutrient deficiency conditions, at which SCD1 is overexpressed. Besides the expected increase in the saturated to unsaturated fatty acid ratio in SCD1 silenced-GBM cells, a striking increase in polyunsaturated chains, particularly in phosphatidylethanolamine and cardiolipin species, was noticed and tentatively correlated with an increase in autophagy (evidenced by the increase in LC3BII/I ratio). The contribution of autophagy to mitigate the impact of SCD1 silencing on GBM cell viability and growth, whose modest inhibition could be correlated with the maintenance of energetically associated mitochondria, was evidenced by using autophagy inhibitors. In conclusion, SCD1 silencing could constitute an important tool to halt GBM resistance to the available treatments, especially when coupled with a mitochondria disrupter chemotherapeutic.     

CircTCF4 Suppresses Proliferation and Differentiation of Goat Skeletal Muscle Satellite Cells Independent from AGO2 Binding

The proliferation and differentiation of mammalian skeletal muscle satellite cells (MuSCs) are highly complicated. Apart from the regulatory signaling cascade driven by the protein-coding genes, non-coding RNAs such as microRNAs (miRNA) and circular RNAs (circRNAs) play essential roles in this biological process. However, circRNA functions in MuSCs proliferation and differentiation remain largely to be elucidated. Here, we screened for an exonic circTCF4 based on our previous RNA-Seq data, specifically expressed during the development of the longest dorsal muscle in goats. Subsequently, the circular structure and whole sequence of circTCF4 were verified using Sanger sequencing. Besides, circTCF4 was spatiotemporally expressed in multiple tissues from goats but strikingly enriched in muscles. Furthermore, circTCF4 suppressed MuSCs proliferation and differentiation, independent of AGO2 binding. Finally, we conducted Poly(A) RNA-Seq using cells treated with small interfering RNA targeting circTCF4 and found that circTCF4 would affect multiple signaling pathways, including the insulin signaling pathway and AMPK signaling pathway related to muscle differentiation. Our results provide additional solid evidence for circRNA regulating skeletal muscle formation.     

MicroRNA-381 Regulates Proliferation and Differentiation of Caprine Skeletal Muscle Satellite Cells by Targeting PTEN and JAG2

In our previous study, microRNA (miR)-381 was found to be the most down-regulated miRNA in skeletal muscle of Liaoning cashmere goats with higher skeletal muscle mass, but the molecular mechanism involved remains unclear. In this study, primary caprine skeletal muscle satellite cells (SMSCs) were isolated and identified. We investigated the effect of miR-381 on the viability, proliferation and differentiation of caprine SMSCs, and the target relationships of miR-381 with jagged canonical Notch ligand 2 (JAG2) and phosphatase and tensin homolog (PTEN). Cells isolated were positive for SMSC-specific marker protein Pax7. This suggests that purified SMSCs were obtained. The expression level of miR-381 achieved a peak value on day 4 after SMSC differentiation, and miR-381 also significantly increased the expression levels of myogenic differentiation marker genes: myosin heavy chain (MyHC), myogenin (MyoG) and myocyte enhancer factor 2C (MEF2C) in differentiated SMSCs, the area of MyHC-positive myotubes and the myogenic index. These findings suggest that miR-381 promoted myogenic differentiation of caprine SMSCs. The CCK8 assay and EDU staining analysis showed that miR-381 mimic both inhibited the viability of SMSCs and decreased the percentage of EDU-labeled positive SMSCs. In contrast, miR-381 inhibitor had the opposite effect with miR-381 mimic. A dual luciferase reporter assay verified that miR-381 can target JAG2 and PTEN by binding to the 3′-untranslated regions (3′-UTR) of the genes. The transfection of miR-381 mimic into caprine SMSCs resulted in decreases in expression levels of JAG2 and PTEN, while miR-381 inhibitor increased the two target genes in expression. This is the first study to reveal the biological mechanisms by which miR-381 regulates caprine SMSC activities.     

新型碳材料质子交换膜燃料电池Pt催化剂载体的研究进展

质子交换膜燃料电池(PEMFC)具有能量转换效率高、功率密度大、室温启动快、噪音低和零污染等特点,有望减少二氧化碳排放量,缓解能源危机,在轨道交通、航空航天等领域具有广阔的应用前景。催化剂是PEMFC的关键材料, Pt催化氧还原反应活性和稳定性好,是广泛使用且很难被取代的电催化剂。然而Pt储量低、价格昂贵,导致PEMFC成本较高,使用Pt载体可减少PEMFC的Pt负载量,提高Pt利用率。碳材料具有成本低廉、比表面积大、孔结构丰富、电导率和表面性质可调等特性,是广泛应用的Pt载体。商用的炭黑载体对Pt的利用效率低,抗电化学腐蚀性较差。为了进一步提高PEMFC的性能和持续性,需要研发能够均匀负载Pt、高效利用Pt、抗电化学腐蚀性强且导电性好的碳载体,进而实现PEMFC的大规模应用。炭气凝胶、碳纳米管和石墨烯等新型碳载体具有独特的结构和性质,可以提高PEMFC性能和寿命,引起了研究者的广泛关注。本文对近年来PEMFC新型碳材料Pt载体的研究进展进行了较为详细的综述,并对其发展趋势作出了适当评论。     

Aminopeptidase N Inhibitors as Pointers for Overcoming Antitumor Treatment Resistance

Aminopeptidase N (APN), also known as CD13 antigen or membrane alanyl aminopeptidase, belongs to the M1 family of the MA clan of zinc metallopeptidases. In cancer cells, the inhibition of aminopeptidases including APN causes the phenomenon termed the amino acid deprivation response (AADR), a stress response characterized by the upregulation of amino acid transporters and synthetic enzymes and activation of stress-related pathways such as nuclear factor kB (NFkB) and other pro-apoptotic regulators, which leads to cancer cell death by apoptosis. Recently, APN inhibition has been shown to augment DR4-induced tumor cell death and thus overcome resistance to cancer treatment with DR4-ligand TRAIL, which is available as a recombinant soluble form dulanermin. This implies that APN inhibitors could serve as potential weapons for overcoming cancer treatment resistance. In this study, a series of basically substituted acetamidophenones and the semicarbazones and thiosemicarbazones derived from them were prepared, for which APN inhibitory activity was determined. In addition, a selective anti-proliferative activity against cancer cells expressing APN was demonstrated. Our semicarbazones and thiosemicarbazones are the first compounds of these structural types of Schiff bases that were reported to inhibit not only a zinc-dependent aminopeptidase of the M1 family but also a metalloenzyme.     

影响SOFC-GT系统热电比的参数模拟分析

随着燃料电池的发展,燃料电池应用领域将越来越广。固体氧化物燃料电池(SOFC)作为高温燃料电池,可以在提供电能的同时对外提供热能。本文以SOFC/GT系统的热电比(对外提供的热能和电能的比)为主要研究对象,通过建立平板型固体氧化物燃料电池系统、燃气轮机等部件的计算模型,计算出不同参数对燃料电池热电比的影响。计算结果表明通过改变电流密度、入口温度和压力等参数,能对系统热电比进行调整。     

Digitoxin Affects Metabolism,ROS Production and Proliferation in Pancreatic Cancer Cells Differently Depending on the Cell Phenotype

Digitoxin has repeatedly shown to have negative effects on cancer cell viability; however, the actual mechanism is still unknown. In this study, we investigated the effects of digitoxin (1–100 nM) in four pancreatic cancer cell lines, BxPC-3, CFPAC-1, Panc-1, and AsPC-1. The cell lines differ in their KRAS/BRAF mutational status and primary tumor or metastasis origin. We could detect differences in the basal rates of cell proliferation, glycolysis, and ROS production, giving the cell lines different phenotypes. Digitoxin treatment induced apoptosis in all four cell lines, but to different degrees. Cells derived from primary tumors (Panc-1 and BxPC-3) were highly proliferating with a high proportion of cells in the S/G2 phase, and were more sensitive to digitoxin treatment than the cell lines derived from metastases (CFPAC-1 and AsPC-1), with a high proportion of cells in G0/G1. In addition, the effects of digitoxin on the rate of glycolysis, ROS production, and proliferation were dependent on the basal metabolism and origin of the cells. The KRAS downstream signaling pathways were not altered by digitoxin treatment, thus the effects exerted by digitoxin were probably disconnected from these signaling pathways. We conclude that digitoxin is a promising treatment in highly proliferating pancreatic tumors.