Downregulation of polo-like kinase 4 in hepatocellular carcinoma associates with poor prognosis

Polo-like kinase 4 (PLK4), belonging to serine/threonine kinase family, is critical for centriole replication and cell cycle progression. PLK4 has been proposed as a tumor suppressor in hepatocellular carcinoma (HCC). However, its expression and significance in HCC have not been well studied. In the present study, we found that PLK4 was markedly downregulated in both HCC cell lines and fresh cancer tissues, using quantitative real-time-PCR and western blot. Immunohistochemistry data also revealed that decreased expression of PLK4 was present in 72.4% (178/246) of HCC tissues, compared with the corresponding adjacent nontumorous tissues. Furthermore, PLK4 expression significantly correlated with clinicopathological parameters, including clinical stage (P=0.034), serum α-fetoprotein (AFP) (P=0.019) and tumor size (P=0.032). Moreover, HCC patients with low PLK4 expression survived shorter than those with high PLK4 expression, as indicated by overall survival (P=0.002) and disease-free survival (P=0.012) assessed by the Kaplan-Meier method. In addition, multivariate analysis suggested PLK4 as an independent predictor of overall survival (HR, 0.556; 95%CI, 0.376-0.822; P=0.003) and disease-free survival (HR, 0.547; 95%CI, 0.382-0.783; P=0.001). Collectively, our study demonstrated that PLK4 was remarkably downregulated in HCC and could be served as a potential prognostic marker for patients with this deadly disease.     

Comparative Analysis of FLC Homologues in Brassicaceae Provides Insight into Their Role in the Evolution of Oilseed Rape

We identified nine FLOWERING LOCUS C homologues (BnFLC) in Brassica napus and found that the coding sequences of all BnFLCs were relatively conserved but the intronic and promoter regions were more divergent. The BnFLC homologues were mapped to six of 19 chromosomes. All of the BnFLC homologues were located in the collinear region of FLC in the Arabidopsis genome except BnFLC.A3b and BnFLC.C3b, which were mapped to noncollinear regions of chromosome A3 and C3, respectively. Four of the homologues were associated significantly with quantitative trait loci for flowering time in two mapping populations. The BnFLC homologues showed distinct expression patterns in vegetative and reproductive organs, and at different developmental stages. BnFLC.A3b was differentially expressed between the winter-type and semi-winter-type cultivars. Microsynteny analysis indicated that BnFLC.A3b might have been translocated to the present segment in a cluster with other flowering-time regulators, such as a homologue of FRIGIDA in Arabidopsis. This cluster of flowering-time genes might have conferred a selective advantage to Brassica species in terms of increased adaptability to diverse environments during their evolution and domestication process.     

Energetic and biomechanical constraints on animal migration distance

Animal migration is one of the great wonders of nature, but the factors that determine how far migrants travel remain poorly understood. We present a new quantitative model of animal migration and use it to describe the maximum migration distance of walking, swimming and flying migrants. The model combines biomechanics and metabolic scaling to show how maximum migration distance is constrained by body size for each mode of travel. The model also indicates that the number of body lengths travelled by walking and swimming migrants should be approximately invariant of body size. Data from over 200 species of migratory birds, mammals, fish, and invertebrates support the central conclusion of the model - that body size drives variation in maximum migration distance among species through its effects on metabolism and the cost of locomotion. The model provides a new tool to enhance general understanding of the ecology and evolution of migration.     

Cdc42-interacting protein-4 promotes TGF-Β1-induced epithelial-mesenchymal transition and extracellular matrix deposition in renal proximal tubular epithelial cells

Cdc42-interacting protein-4 (CIP4) is an F-BAR (Fer/CIP4 and Bin, amphiphysin, Rvs) family member that regulates membrane deformation and endocytosis, playing a key role in extracellular matrix (ECM) deposition and invasion of cancer cells. These processes are analogous to those observed during the initial epithelial-mesenchymal transition (EMT) of renal tubular epithelial cells. The role of CIP4 in renal tubular EMT and renal tubulointerstitial fibrosis was investigated over the course of the current study, demonstrating that the expression of CIP4 increased in the tubular epithelia of 5/6-nephrectomized rats and TGF-β1 treated HK-2 cells. Endogenous CIP4 evidenced punctate localization throughout the cytosol, with elevated levels observed in the perinuclear region of HK-2 cells. Subsequent to TGF-β1 treatment, CIP4 expression increased, forming clusters at the cell periphery that gradually redistributed into the cytoplasm. Simultaneously, EMT induction in cells was confirmed by the prevalence of morphological changes, loss of E-cadherin, increase in α-SMA expression, and secretion of fibronectin. Overexpression of CIP4 promoted characteristics similar to those commonly observed in EMT, and small interfering RNA (siRNA) molecules capable of CIP4 knockdown were used to demonstrate reversed EMT. Cumulatively, results of the current study suggest that CIP4 promotes TGF-β1-induced EMT in tubular epithelial cells. Through this mechanism, CIP4 is capable of inducing ECM deposition and exacerbating progressive fibrosis in chronic renal failure.     

OLFML3 expression is decreased during prenatal muscle development and regulated by microRNA-155 in pigs

The Olfactomedin-like 3 (OLFML3) gene has matrix-related function involved in embryonic development. MicroRNA-155 (miR-155), 21- to 23-nucleotides (nt) noncoding RNA, regulated myogenesis by target mRNA. Our LongSAGE analysis suggested that OLFML3 gene was differently expressed during muscle development in pig. In this study, we cloned the porcine OLFML3 gene and detected its tissues distribution in adult Tongcheng pigs and dynamical expression in developmental skeletal muscle (12 prenatal and 10 postnatal stages) from Landrace (lean-type) and Tongcheng (obese-type) pigs. Subsequently, we analyzed the interaction between OLFML3 and miR-155. The OLFML3 was abundantly expressed in liver and pancreas, moderately in lung, small intestine and placenta, and weakly in other tissues and postnatal muscle. There were different dynamical expression patterns between Landrace and Tongcheng pigs during prenatal skeletal muscle development. The OLFML3 was down-regulated (33-50 days post coitus, dpc), subsequently up-regulated (50-70 dpc), and then down-regulated (70-100 dpc) in Landrace pigs, while in Tongcheng pigs, it was down-regulated (33-50 dpc), subsequently up-regulated (50-55 dpc) and then down-regulated (55-100 dpc). There was higher expression in Tongcheng than Landrace in prenatal muscle from 33 to 60 dpc, and opposite situation from 65 to 100 dpc. Dual luciferase assay and real time PCR documented that OLFML3 expression was regulated by miR-155 at mRNA level. Our research indicated that OLFML3 gene may affect prenatal skeletal muscle development and was regulated by miR-155. These finding will help understanding biological function and expression regulation of OLFML3 gene in mammal animals.     

Anti-cancer activities of tea epigallocatechin-3-gallate in breast cancer patients under radiotherapy

The purpose of this study was to test the hypothesis that administration of epigallocatechin-3-gallate (EGCG), a polyphenol present in abundance in widely consumed tea, inhibits cell proliferation, invasion, and angiogenesis in breast cancer patients. EGCG in 400 mg capsules was orally administered three times daily to breast cancer patients undergoing treatment with radiotherapy. Parameters related to cell proliferation, invasion, and angiogenesis were analyzed while blood samples were collected at different time points to determine efficacy of the EGCG treatment. Compared to patients who received radiotherapy alone, those given radiotherapy plus EGCG for an extended time period (two to eight weeks) showed significantly lower serum levels of vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), and reduced activation of metalloproteinase-9 and metalloproteinase-2 (MMP9/MMP2). Addition of sera obtained from patients treated with combination of radiotherapy and EGCG feeding for 2-8 weeks to in vitro cultures of highly-metastatic human MDA-MB-231 breast cancer cells resulted in the following significant changes: (1) suppression of cell proliferation and invasion; (2) arrest of cell cycles at the G0/G1 phase; (3) reduction of activation of MMP9/MMP2, expressions of Bcl-2/Bax, c-Met receptor, NF-κB, and the phosphorylation of Akt. MDA-MB-231 cells exposed to 5-10 μM EGCG also showed significant augmentation of the apoptosis inducing effects of γ-radiation, concomitant with reduced NF-κB protein level and AKT phosphorylation. These results provide hitherto unreported evidence that EGCG potentiated efficacy of radiotherapy in breast cancer patients, and raise the possibility that this tea polyphenol has potential to be a therapeutic adjuvant against human metastatic breast cancer.     

Developmental changes and regional localization of Dspp, Mepe, Mimecan and Versican in postnatal developing mouse teeth

It has been implicated noncollagenous proteins act as important regulators during odontogenesis. To test the hypothesis that the roles of Dspp, Mepe, Versican and Mimecan in the regulation of odontogenesis may be complementary, comparative investigations on the localization of four proteins were performed by immunohistochemical staining using mouse first molar at different developmental stages as a model. In postnatal 1- day-old mice, all the proteins, excluding Mepe, showed co-expression in young odontoblasts. At postnatal 3, strong immunoreactions for all proteins were detected in odontoblasts. Interestingly, Mepe was present within both cytoplasm and nucleus in odontoblasts. In mice older than 5 days, the expression of Dspp, Mimecan and Versican accumulated in subodontoblastic layer of the coronal pulp at high levels while the co-expression of Mepe and Mimecan significantly existed in predentin. The temporal-spatial specific pattern and unique co-localization of Dspp, Mepe, Mimecan and Versican suggest they play complementary roles during odontogenesis.     

Involvement of Ser94 in RNase HIII from Chlamydophila pneumoniae in the recognition of a single ribonucleotide misincorporated into double-stranded DNA

We recently provided the first report that RNase HIII can cleave a DNA-rN₁-DNA/DNA substrate (rN₁, one ribonucleotide) in vitro. In the present study, mutagenesis analyses and molecular dynamics (MD) simulations were performed on RNase HIII from Chlamydophila pneumoniae AR39 (CpRNase HIII). Our results elucidate the mechanism of ribonucleotide recognition employed by CpRNase HIII, indicating that the G95/K96/G97 motif of CpRNase HIII represents the main surface interacting with single ribonucleotides, in a manner similar to that of the GR(K)G motif of RNase HIIs. However, CpRNase HIII lacks the specific tyrosine required for RNase HII to recognize single ribonucleotides in double-stranded DNA (dsDNA). Interestingly, MD shows that Ser94 of CpRNase HIII forms a stable hydrogen bond with the deoxyribonucleotide at the (5')RNA–DNA(3') junction, moving this nucleotide away from the chimeric ribonucleotide. This movement appears to deform the nucleic acid backbone at the RNA–DNA junction and allows the ribonucleotide to interact with the GKG motif. Based on the inferences drawn from MD simulations, biochemical results indicated that Ser94 was necessary for catalytic activity on the DNA-rN₁-DNA/DNA substrate; mutant S94V could bind this substrate but exhibited no cleavage. Mismatches opposite the single ribonucleotide misincorporated in dsDNA inhibited cleavage by CpRNase HIII to varying degrees but did not interfere with CpRNase/substrate binding. Further MD results implied that mismatches impair the interaction between Ser94 and the deoxyribonucleotide at the RNA–DNA junction. Consequently, recognition of the misincorporated ribonucleotide was disturbed. Our results may help elucidate the distinct substrate-recognition properties of different RNase Hs.     

Therapeutic potential of in utero mesenchymal stem cell (MSCs) transplantation in rat foetuses with spina bifida aperta

Neural tube defects (NTDs) are complex congenital malformations resulting from incomplete neurulation in embryo. Despite surgical repair of the defect, most of the patients who survive with NTDs have a multiple system handicap due to neuron deficiency of the defective spinal cord. In this study, we successfully devised a prenatal surgical approach and transplanted mesenchymal stem cells (MSCs) to foetal rat spinal column to treat retinoic acid induced NTDs in rat. Transplanted MSCs survived, grew and expressed markers of neurons, glia and myoblasts in the defective spinal cord. MSCs expressed and perhaps induced the surrounding spinal tissue to express neurotrophic factors. In addition, MSC reduced spinal tissue apoptosis in NTD. Our results suggested that prenatal MSC transplantation could treat spinal neuron deficiency in NTDs by the regeneration of neurons and reduced spinal neuron death in the defective spinal cord.