The Downregulation of MiR-182 Is Associated with the Growth and Invasion of Osteosarcoma Cells through the Regulation of TIAM1 Expression

BackgroundOsteosarcoma is the most common primary bone malignancy in children and young adults. Increasing results suggest that discovery of microRNAs (miRNAs) might provide a novel therapeutical target for osteosarcoma.MethodsMiR-182 expression level in osteosarcoma cell lines and tissues were assayed by qRT-PCR. MiRNA mimics or inhibitor were transfected for up-regulation or down-regulation of miR-182 expression. Cell function was assayed by CCK8, migration assay and invasion assay. The target genes of miR-182 were predicated by bioinformatics algorithm (TargetScan Human).ResultsMiR-182 was down-regulated in osteosarcoma tissues and cell lines. Overexpression of miR-182 inhibited tumor growth, migration and invasion. Subsequent investigation revealed that TIAM1 was a direct and functional target of miR-182 in osteosarcoma cells. Overexpression of miR-182 impaired TIAM1-induced inhibition of proliferation and invasion in osteosarcoma cells.ConclusionsDown-expression of miR-182 in osteosarcoma promoted tumor growth, migration and invasion by targeting TIAM1. MiR-182 might act as a tumor suppressor gene whose down-regulation contributes to the progression and metastasis of osteosarcoma, providing a potential therapy target for osteosarcoma patients.     

α‐ketoglutarate delays age‐related fertility decline in mammals

The fecundity reduction with aging is referred as the reproductive aging which comes earlier than that of chronological aging. Since humans have postponed their childbearing age, to prolong the reproductive age becomes urgent agenda for reproductive biologists. In the current study, we examined the potential associations of α‐ketoglutarate (α‐KG) and reproductive aging in mammals including mice, swine, and humans. There is a clear tendency of reduced α‐KG level with aging in the follicle fluids of human. To explore the mechanisms, mice were selected as the convenient animal model. It is observed that a long term of α‐KG administration preserves the ovarian function, the quality and quantity of oocytes as well as the telomere maintaining system in mice. α‐KG suppresses ATP synthase and alterations of the energy metabolism trigger the nutritional sensors to down‐regulate mTOR pathway. These events not only benefit the general aging process but also maintain ovarian function and delay the reproductive decline. Considering the safety of the α‐KG as a naturally occurring molecule in energy metabolism, its utility in reproduction of large mammals including humans deserves further investigation.     

Matrix metalloproteinase-9 is up-regulated by CCL19/CCR7 interaction via PI3K/Akt pathway and is involved in CCL19-driven BMSCs migration

C–C chemokine receptor 7 (CCR7) and its ligands CCL19 contributes to the directional migration of certain cancer cell lines, but its role in the migration of BMSCs remains vague. The aim of this study was to determine the possible interaction between CCL19-induced conditions and matrix metalloproteinases-9 (MMP9) expression in BMSCs. Cell migration using Transwell assay indicated that activation of CCR7 by its specific ligand, exogenous chemokine ligand 19 (CCL19), was associated with a significant linear increase. Western blot and real-time PCR indicated that CCL19/CCR7 significantly upregulated expression of MMP9, which is related to metastasis-associated genes. The CCL19/CCR7 interaction significantly enhanced phosphorylation of Akt, as measured by Western blot. P-Akt and MMP9 protein expression exhibited a time-dependent pattern, and the peak was at 48 h. LY294002 significantly abolished the effects of exogenous CCL19. These results suggest that CCL19/CCR7 contributes to the migration of BMSCs by upregulating MMP9 potentially via the PI3K/Akt pathway.     

Correlation between Activation of PI3K/AKT/mTOR Pathway and Prognosis of Breast Cancer in Chinese Women

Background

Abnormal activation of PI3K/AKT/mTOR (PAM) pathway, caused by PIK3CA mutation, KRAS mutation, PTEN loss, or AKT1 mutation, is one of the most frequent signaling abnormalities in breast carcinoma. However, distribution and frequencies of mutations in PAM pathway are unclear in breast cancer patients from the mainland of China and the correlation between these mutations and breast cancer outcome remains to be identified.

Methods

A total of 288 patients with invasive ductal breast cancer were recruited in this study. Mutations in PIK3CA (exons 4, 9 and 20), KRAS (exon 2) and AKT1 (exon 3) were detected using Sanger sequencing. PTEN loss was measured by immunohistochemistry assay. Correlations between these genetic aberrations and clinicopathological features were analyzed.

Results

The frequencies of PIK3CA mutation, KRAS mutation, AKT1 mutation and PTEN loss were 15.6%, 1.8%, 4.4% and 35.3%, respectively. However, except for PTEN loss, which was tied to estrogen receptor (ER) status, these alterations were not associated with other clinicopathological features. Survival analysis demonstrated that PIK3CA mutation, PTEN loss and PAM pathway activation were not associated with disease-free survival (DFS). Subgroup analysis of patients with ER positive tumors revealed that PIK3CA mutation more strongly reduced DFS compared to wild-type PIK3CA (76.2% vs. 54.2%; P = 0.011). PIK3CA mutation was also an independent factor for bad prognosis in ER positive patients.

Conclusions

AKT1, KRAS and PIK3CA mutations and PTEN loss all exist in women with breast cancer in the mainland China. PIK3CA mutation may contribute to the poor outcome of ER positive breast carcinomas, providing evidence for the combination of PI3K/AKT/mTOR inhibitors and endocrine therapy.     

Rational design of cationic antimicrobial peptides by the tandem of leucine-rich repeat

Antimicrobial peptides represent ancient host defense effector molecules present in organisms across the evolutionary spectrum. Lots of antimicrobial peptides were synthesized based on well-known structural motif widely existed in a variety of lives. Leucine-rich repeats (LRRs) are sequence motifs present in over 60,000 proteins identified from viruses, bacteria, and eukaryotes. To elucidate if LRR motif possesses antimicrobial potency, two peptides containing one or two LRRs were designed. The biological activity and membrane–peptide interactions of the peptides were analyzed. The results showed that the tandem of two LRRs exhibited similar antibacterial activity and significantly weaker hemolytic activity against hRBCs than the well-known membrane active peptide melittin. The peptide with one LRR was defective at antimicrobial and hemolytic activity. The peptide containing two LRRs formed α-helical structure, respectively, in the presence of membrane-mimicking environment. LRR-2 retained strong resistance to cations, heat, and some proteolytic enzymes. The blue shifts of the peptides in two lipid systems correlated positively with their biological activities. Other membrane-peptide experiments further provide the evidence that the peptide with two LRRs kills bacteria via membrane-involving mechanism. The present study increases our new understanding of well-known LRR motif in antimicrobial potency and presents a potential strategy to develop novel antibacterial agents.     

Extensive pyrosequencing reveals frequent intra-genomic variations of internal transcribed spacer regions of nuclear ribosomal DNA

Background

Internal transcribed spacer of nuclear ribosomal DNA (nrDNA) is already one of the most popular phylogenetic and DNA barcoding markers. However, the existence of its multiple copies has complicated such usage and a detailed characterization of intra-genomic variations is critical to address such concerns.

Methodology/Principal Findings

In this study, we used sequence-tagged pyrosequencing and genome-wide analyses to characterize intra-genomic variations of internal transcribed spacer 2 (ITS2) regions from 178 plant species. We discovered that mutation of ITS2 is frequent, with a mean of 35 variants per species. And on average, three of the most abundant variants make up 91% of all ITS2 copies. Moreover, we found different congeneric species share identical variants in 13 genera. Interestingly, different species across different genera also share identical variants. In particular, one minor variant of ITS2 in Eleutherococcus giraldii was found identical to the ITS2 major variant of Panax ginseng, both from Araliaceae family. In addition, DNA barcoding gap analysis showed that the intra-genomic distances were markedly smaller than those of the intra-specific or inter-specific variants. When each of 5543 variants were examined for its species discrimination efficiency, a 97% success rate was obtained at the species level.

Conclusions

Identification of identical ITS2 variants across intra-generic or inter-generic species revealed complex species evolutionary history, possibly, horizontal gene transfer and ancestral hybridization. Although intra-genomic multiple variants are frequently found within each genome, the usage of the major variants alone is sufficient for phylogeny construction and species determination in most cases. Furthermore, the inclusion of minor variants further improves the resolution of species identification.     

Cardiac telocytes exist in the adult Xenopus tropicalis heart

Recent research has revealed that cardiac telocytes (CTs) play an important role in cardiac physiopathology and the regeneration of injured myocardium. Recently, we reported that the adult Xenopus tropicalis heart can regenerate perfectly in a nearly scar‐free manner after injury via apical resection. However, whether telocytes exist in the X tropicalis heart and are affected in the regeneration of injured X tropicalis myocardium is still unknown. The present ultrastructural and immunofluorescent double staining results clearly showed that CTs exist in the X tropicalis myocardium. CTs in the X tropicalis myocardium were mainly twined around the surface of cardiomyocyte trabeculae and linked via nanocontacts between the ends of the telopodes, forming a three‐dimensional network. CTs might play a role in the regeneration of injured myocardium.     

家蚕光泽小眼(varnished eye)突变基因的精细定位

家蚕(Bombyx mori)光泽小眼(varnished eye,ve)突变体是家蚕突变品种中少数关于家蚕复眼形态异常的自然隐性突变品种之一,表现为成虫复眼小,表面富有光泽,有瘤状突起;小眼数量少且不规则。经典遗传学连锁图谱将ve基因定位在第6连锁群32.2座位,但到目前为止,该突变性状的形成机理仍不清楚。文章以突变品种ve和对照品种Dz为亲本,杂交产生的F1代雄个体与轮回亲本ve雌个体回交产生的BC1代为材料进行ve基因的精细定位。通过对ve低密度连锁图谱分析发现,ve基因被定位在SNP3~SNP6之间,物理图谱距离大约为1.2 Mb。利用1563个BC1代个体构建ve高密度连锁图谱,最终将ve基因定位在SNP5~SNP61之间,物理图谱距离大约为221.8 kb。通过家蚕基因数据库对ve最终定位区域内进行预测基因检索,发现有6个预测基因。对6个预测基因进行生物信息学分析和测序,这些候选基因都有可能参与家蚕复眼形成,但在编码区没有发现ve特异的突变位点;对这些候选基因进行表达分析,发现编号为BGIBMGA013642的候选基因在ve复眼形成过程中的表达量明显比正常对照Dz低,推测该基因为最佳候选基因。