Up-regulation of casein kinase 1ε is involved in tau pathogenesis in Alzheimer's disease.

Hyperphosphorylation of tau and imbalanced expression of 3R-tau and 4R-tau as a result of dysregulation of tau exon 10 splicing are believed to be pivotal to the pathogenesis of tau pathology, but the molecular mechanism leading to the pathologic tau formation in Alzheimer's disease (AD) brain is not fully understood. In the present study, we found that casein kinase 1ε (CK1ε) was increased significantly in AD brains. Overexpression of CK1ε in cultured cells led to increased tau phosphorylation at many sites. Moreover, we found that CK1ε suppressed tau exon 10 inclusion. Levels of CK1ε were positively correlated to tau phosphorylation, 3R-tau expression and tau pathology, and negatively correlated to 4R-tau in AD brains. Overexpression of CK1ε in the mouse hippocampus increased tau phosphorylation and impaired spontaneous alternation behavior. These data suggest that CK1ε is involved in the regulation of tau phosphorylation, the alternative splicing of tau exon 10, and cognitive performance. Up-regulation of CK1ε might contribute to tau pathology by hyperphosphorylating tau and by dysregulating the alternative splicing of tau exon 10 in AD.

Ancestral resurrection of anthropoid estrogen receptor ß demonstrates functional consequences of positive selection.

Anthropoid primates arose during the Eocene approximately 55 million years ago (mya), and extant anthropoids share a most recent common ancestor ∼40mya. Paleontology has been very successful at describing the morphological phenotypes of extinct anthropoids. Less well understood is the molecular biology of these extinct species as well as the phenotypic consequences of evolutionary variation in their genomes. Here we resurrect the most recent common ancestral anthropoid estrogen receptor ß gene (ESR2) and demonstrate that the function of this ancestral estrogen receptor has been maintained during human descent but was altered during early New World monkey (NWM) evolution by becoming a more potent transcriptional activator. We tested hypotheses of adaptive evolution in the protein coding sequences of ESR2, and determined that ESR2 evolved via episodic positive selection on the NWM stem lineage. We separately co-transfected ESR2 constructs for human, NWM, and the anthropoid ancestor along with reporter gene vectors and performed hormone binding dose response experiments that measure transactivation activity. We found the transactivation potentials of the ancestral and human sequences to be significantly lower (p<0.0001 in each comparison) than that of the NWM when treated with estradiol, the most prevalent estrogen. We conclude the difference in fold activation is due to positive selection in the NWM ERß ligand binding domain. Our study validates inferential methods for detecting adaptive evolution that predict functional consequences of nucleotide substitutions and points a way toward examining the functional consequences of positive Darwinian selection.

Involvement of human chorionic gonadotropin in regulating vasculogenic mimicry and hypoxia-inducible factor-1α expression in ovarian cancer cells.

BACKGROUND: Human chorionic gonadotropin (hCG) can play a crucial role in angiogenesis. In the present study, we focused on hCG to gain insight into its potential effects on vasculogenic mimicry (VM) in ovarian cancer cells. METHODS: Ovarian cancer OVCAR-3 cells were incubated with different concentrations of recombinant hCG in 3-dimensional cultures. VM was identified by morphological observations and vascular endothelial cell marker detection in OVCAR-3 cells. Expression of hCG, hypoxia-inducible factor-1α (HIF-1α), and the endothelial cell markers CD31, VEGF, and factor VIII were detected by reverse transcription polymerase chain reaction and western blotting. The effect of hCG on endothelial cell-marker expression in ovarian cancer cells was further explored using small interfering RNA (siRNA) and plasmid-based approaches. RESULTS: Incubation of OVCAR-3 cells with recombinant hCG induced vessel-like network formation, which was accompanied by significant elevation of vascular marker expression. Attenuation of hCG expression by siRNA in OVCAR-3 cells suppressed the expression of endothelial cell markers and HIF-1α by tumour cells. Overexpression of hCG in OVCAR-3 cells resulted in increased expression of endothelial cell markers and HIF-1α. CONCLUSIONS: HCG was crucial for changing the phenotype of OVCAR-3 cells to endothelial-like cells. The effect of hCG induction on VM in ovarian cancer cells is potentially associated with HIF-1α.

Cyclic AMP-dependent protein kinase enhances SC35-promoted Tau exon 10 inclusion.

Alternative splicing of tau exon 10 generates tau with three or four microtubule-binding repeats (3R-tau or 4R-tau). The ratio of 3R-tau to 4R-tau is approximately 1:1 in the adult normal human brain. Disturbances in the ratio result in neurodegenerative tauopathies. Splicing factor SC35 acts on a SC35-like element located at the 5' end of tau exon 10 and promotes tau exon 10 inclusion. Here, we report that protein kinase (PKA) was able to interact and phosphorylate SC35. Activation or overexpression of PKA catalytic subunits promoted SC35-mediated tau exon 10 inclusion. Four PKA catalytic subunits, α1, α2, ß1, and ß2, all enhanced SC35-promoted tau exon 10 inclusion. SC35 has four putative PKA phosphorylation sites, Ser121, Ser128, Ser130, and Ser171. Pseudophosphorylation (SC354E) and blockage (SC354A) of phosphorylation of SC35 at these four sites increased and decreased, respectively, SC35's ability to promote tau exon 10 inclusion. Moreover, PKA catalytic subunits no longer further enhanced tau exon 10 inclusion when these four were mutated to either alanine or glutamate. These results suggest that PKA interacts with and phosphorylates SC35 and enhances SC35-promoted tau exon 10 inclusion. In Alzheimer's brain, down-regulation of the PKA pathway could lead to dysregulation of tau exon 10, contributing to tau pathogenesis.

Phylogenetics and evolution of Trx SET genes in fully sequenced land plants.

Plant Trx SET proteins are involved in H3K4 methylation and play a key role in plant floral development. Genes encoding Trx SET proteins constitute a multigene family in which the copy number varies among plant species and functional divergence appears to have occurred repeatedly. To investigate the evolutionary history of the Trx SET gene family, we made a comprehensive evolutionary analysis on this gene family from 13 major representatives of green plants. A novel clustering (here named as cpTrx clade), which included the III-1, III-2, and III-4 orthologous groups, previously resolved was identified. Our analysis showed that plant Trx proteins possessed a variety of domain organizations and gene structures among paralogs. Additional domains such as PHD, PWWP, and FYR were early integrated into primordial SET-PostSET domain organization of cpTrx clade. We suggested that the PostSET domain was lost in some members of III-4 orthologous group during the evolution of land plants. At least four classes of gene structures had been formed at the early evolutionary stage of land plants. Three intronless orphan Trx SET genes from the Physcomitrella patens (moss) were identified, and supposedly, their parental genes have been eliminated from the genome. The structural differences among evolutionary groups of plant Trx SET genes with different functions were described, contributing to the design of further experimental studies.

Role of hCG in vasculogenic mimicry in OVCAR-3 ovarian cancer cell line.

OBJECTIVES: Vasculogenic mimicry (VM) is induced by hypoxia in 3-dimensional culture of ovarian cancer cells. By using this 3D model system, we explored the expression of human chorionic gonadotropin (hCG) and its effects on VM formation in ovarian cancer cell line OVCAR-3 both under normoxic and hypoxic conditions. METHODS: Vasculogenic mimicry was identified by morphological observation and detection of vascular cell marker expressed by OVCAR-3. Potential formation of tumor channels was observed by light microscopy and scanning electron microscopy. Expression of vascular cell marker CD31, vascular endothelial growth factor, and Factor VIII were detected by flow cytometry, immunochemistry, and Western blot. Expression of hCG was investigated by enzyme-linked immunosorbent assay, chemiluminescence immunoassay, real-time polymerase chain reaction (PCR), and Western blot. Expression of hypoxia-inducible factor-1α (HIF-1α) was detected by real-time PCR, Western blot, and blocked by small interference RNA. Incubation of OVCAR-3 with recombinant hCG was used to evaluate its effect on VM formation. The specificity of the effect of hCG was assessed by inhibition with the neutralizing anti-hCG antibody. RESULTS: OVCAR-3 cells formed vessel-like network structures and expressed vascular marker significantly under hypoxia in 3D. The expression level of hCG under hypoxia was significantly higher than that under normoxia. Attenuating hypoxia-inducible factor (HIF)-1α expression via small interference RNA resulted in a significantly decreased hCG expression in OVCAR-3, which indicated that the effect of hypoxia on hCG expression was mediated through HIF-1α. Treatment of OVCAR-3 with 5000 mU/mL hCG resulted in the presence of tumor cell-lined vasculature and significant elevation in vascular marker expression, even under normoxia. Expression level of vascular marker and HIF-1α in OVCAR-3 increased in response to hCG treatment in a dose-dependent manner. The effect of hCG was inhibited by the neutralizing anti-hCG antibody. CONCLUSIONS: Human chorionic gonadotropin has the potential to induce VM in OVCAR-3. Human chorionic gonadotropin might have synergistic hypoxia-induced effect on vascular marker and HIF-1α expression.

[Improvement of the bilingual teaching of genetics using classic papers].

More and more colleges have recognized the importance of bilingual teaching in improvement students' capability to integrate the specialized knowledge with the foreign language. Bilingual teaching courses have been designed to enhance the innovation of high education and improve the culture quality of students. Genetics is one of the most important courses for undergraduate students majored in the region of life sciences. However, in the case of genetics, the advisable model to carry out bilingual teaching and the matter of great concern are ambiguous and need evidence accumulated by more teaching experiments. The classic papers in genetics are valuable resources to the bilingual teaching of genetics. This paper analyzed the role of classic papers in the bilingual teaching of genetics and discussed the methods for improving the bilingual teaching of genetics.

Transcriptional regulation of the novel Toll-like receptor Tlr13.

Little has been known about Tlr13 (Toll-like receptor 13), a novel member of the Toll-like receptor family. To elucidate the molecular basis of murine Tlr13 gene expression, the activity of the Tlr13 gene promoter was characterized. Reporter gene analysis and electrophoretic mobility shift assays demonstrated that Tlr13 gene transcription was regulated through three cis-acting elements that interacted with the Ets2, Sp1, and PU.1 transcription factors. Furthermore, our work suggests that these transcription factors may cooperate, culminating in maximal transcription of the Tlr13 gene. In contrast, NF-kappaB appeared to act as an inhibitor of Tlr13 transcription. Overexpression of Ets2 caused a strong increase in the transcriptional activity of the Tlr13 promoter; however, overexpression of NF-kappaB p65 dramatically inhibited it. Additionally, interferon-beta is capable of acting Tlr13 transcription, but the activated signaling of lipopolysaccharide/TLR4 and peptidoglycan/TLR2 strongly inhibited the Tlr13 gene promoter. Thus, these findings reveal the mechanism of Tlr13 gene regulation, thereby providing insight into the function of Tlr13 in the immune response to pathogen.

[A preliminary exploration into medical genetics teaching to international students].

Medical education to international students has become an important part of higher education in China. Medical genetics is an essential and required course for international medical students. However, the internationalization of higher education in China has challenged the traditional teaching style of medical genetics. In this article, we discussed current situation and challenges in medical genetics teaching to international students, summarized special features and problems we encountered in teaching Indian students, and proposed some practical strategies to address these challenges and to improve the teaching.

The human progesterone receptor shows evidence of adaptive evolution associated with its ability to act as a transcription factor.

The gene encoding the progesterone receptor (PGR) acts as a transcription factor, and participates in the regulation of reproductive processes including menstruation, implantation, pregnancy maintenance, parturition, mammary development, and lactation. Unlike other mammals, primates do not exhibit progesterone withdrawal at the time of parturition. Because progesterone-mediated reproductive features vary among mammals, PGR is an attractive candidate gene for studies of adaptive evolution. Thus, we sequenced the progesterone receptor coding regions in a diverse range of species including apes, Old World monkeys, New World monkeys, prosimian primates, and other mammals. Adaptive evolution occurred on the human and chimpanzee lineages as evidenced by statistically significant increases in nonsynonymous substitution rates compared to synonymous substitution rates. Positive selection was rarely observed in other lineages. In humans, amino acid replacements occurred mostly in a region of the gene that has been shown to have an inhibitory function (IF) on the ability of the progesterone receptor to act as a transcription factor. Moreover, many of the nonsynonymous substitutions in primates occurred in the N-terminus. This suggests that cofactor interaction surfaces might have been altered, resulting in altered progesterone-regulated gene transcriptional effects. Further evidence that the changes conferred an adaptive advantage comes from SNP analysis indicating only one of the IF changes is polymorphic in humans. In chimpanzees, amino acid changes occurred in both the inhibitory and transactivation domains. Positive selection provides the basis for the hypothesis that changes in structure and function of the progesterone receptor during evolution contribute to the diversity of primate reproductive biology, especially in parturition.

Evolution of the mammalian placenta revealed by phylogenetic analysis.

The placenta is essential for the success of therian mammalian reproduction. Intense selective pressure has shaped changes in placental anatomy and function during mammalian cladogenesis. Here we challenge the view that the hemochorial placenta is a derived feature in haplorhine primates. Using phylogenetic and statistical analyses of molecular and morphological data, we demonstrate that the ancestral eutherian mammalian placenta had the distinctive features of (i) hemochorial placental interface, (ii) a discoid shape, and (iii) a labyrinthine maternofetal interdigitation. These results reveal that the first eutherians had a deeply invasive placenta and imply that the major role of the placenta in sustaining pregnancy and promoting gestational development existed throughout the eutherian lineage that descended to humans from the last common ancestor of placental mammals. The ancestral state reconstructions demonstrate both clade-specific patterns of placentation and specific cases of convergent evolution within individual eutherian clades. Determining the mammalian pattern of change in placental morphology is important for understanding the evolutionary pressures faced by these lineages. The effects of selection pressures on the efficiency of placentation may stem from changes in nutritional demand, gestational length, number of embryos per pregnancy, uterine shape, and maternal body constitution. The influence of these factors on placental development needs further investigation.