Comparative sequence analysis of imprinted genes between human and mouse to reveal imprinting signatures

We performed a comparative genomic sequence analysis between human and mouse for 24 imprinted genes on human chromosomes 1, 6, 7, 11, 13, 14, 15, 18, 19, and 20. The MEME program was used to search for motifs within conserved sequences among the imprinted genes and we then used the MAST program to analyze for the presence or absence of motifs in the imprinted genes and 128 nonimprinted genes. Our analysis identified 15 motifs that were significantly enriched in the imprinted genes. We generated a logistic regression model by combining multiple motifs as input variables and the 24 imprinted genes and the 128 nonimprinted genes as a training set. The accuracy, sensitivity, and specificity of our model were 98, 92, and 99%, respectively. The model was further validated by an open test on 12 additional imprinted genes. The motifs identified in this study are novel imprinting signatures, which should improve our understanding of genomic imprinting and the role of genomic imprinting in human diseases.     

Plasticity of human chromosome 3 during primate evolution

Comparative mapping of more than 100 region-specific clones from human chromosome 3 in Bornean and Sumatran orangutans, siamang gibbon, and Old and New World monkeys allowed us to reconstruct ancestral simian and hominoid chromosomes. A single paracentric inversion derives chromosome 1 of the Old World monkey Presbytis cristata from the simian ancestor. In the New World monkey Callithrix geoffroyi and siamang, the ancestor diverged on multiple chromosomes, through utilizing different breakpoints. One shared and two independent inversions derive Bornean orangutan 2 and human 3, implying that neither Bornean orangutans nor humans have conserved the ancestral chromosome form. The inversions, fissions, and translocations in the five species analyzed involve at least 14 different evolutionary breakpoints along the entire length of human 3; however, particular regions appear to be more susceptible to chromosome reshuffling. The ancestral pericentromeric region has promoted both large-scale and micro-rearrangements. Small segments homologous to human 3q11.2 and 3q21.2 were repositioned intrachromosomally independent of the surrounding markers in the orangutan lineage. Breakage and rearrangement of the human 3p12.3 region were associated with extensive intragenomic duplications at multiple orangutan and gibbon subtelomeric sites. We propose that new chromosomes and genomes arise through large-scale rearrangements of evolutionarily conserved genomic building blocks and additional duplication, amplification, and/or repositioning of inherently unstable smaller DNA segments contained within them.     

Genetically altered mice to evaluate glutathione homeostasis in health and disease

The tripeptide glutathione (GSH) is part of an integrated antioxidant system that protects cells and tissues from oxidative damage. Oxidative stress can result from exposure to excessive amounts of endogenous and exogenous electrophiles. Until recently, animal and cell model systems used to investigate the role of GSH in disease processes had employed chemical agents that deplete cellular GSH by inhibiting GSH synthesis or by reacting chemically with GSH. Such models have proven useful, but questions concerning nonspecific effects of such chemicals remain. Recently, our laboratories and others have developed mouse models with genetic deficiencies in enzymes of the GSH biosynthetic pathway. This review focuses on the regulation of GSH homeostasis and, specifically, the new GSH-deficient mouse models that have been developed. These models will improve our understanding of the role of GSH in animal and human diseases.     

Chemical composition of the essential oils of two Alpinia species from Hainan Island, China

The essential oils of two Alpinia species, ie. A. hainanensis and A. katsumadai, from Hainan Island, China were analyzed by using GC-MS. The major constituents in the leaf oil of A. hainanensis were ocimene (27.4%), beta-pinene (10.1%), 9-octadecenoic acid (6.5%), n-hexadecanoic acid (5.8%), 9,12-octadecadienoic acid (5.4%), and terpinen (4.3%). The oil constituents obtained from the flowers of A. hainanensis were ocimene (39.8%), beta-pinene (17.7%), terpinene (5.5%), p-menth-1-en-ol (4.9%), caryophyllene (4.9%), and phellandrene (4.4%). In A. katsumadai, the major constituents in the leaf oil were p-menth-1-en-ol (22.0%), terpinen (19.0%), 4-carene (9.1%), 1,8-cineole (8.3%), and camphor (5.6%). The major constituents in the flower oil were p-menth-1-en-ol (21.3%), 1,8-cineole (20.2%), terpinen (12.6%), phellandrene (7.0%), 4-carene (6.4%), and beta-pinene (5.2%).     

Arbuscular mycorrhizal fungi associated with common pteridophytes in Dujiangyan,southwest China

The colonization and diversity of arbuscular mycorrhizal (AM) fungi associated with common pteridophytes were investigated in Dujiangyan, southwest China. Of the 34 species of ferns from 16 families collected, 31 were colonized by AM fungi. The mean percentage root length colonized was 15%, ranging from 0 to 47%. Nineteen species formed Paris-type and 10 intermediate-type AM. In two ferns, only rare intercellular non-septate hyphae or vesicles were observed in the roots and AM type could not be determined. Of the 40 AM fungal taxa belonging to five genera isolated from rooting-zone soils, 32 belonged to Glomus, five to Acaulospora, one to Archaeospora, one to Entrophospora, and one to Gigaspora. Acaulospora and Glomus were the dominant genera and Glomus versiforme was the most common species. The average AM spore density was 213 per 100 g air-dried soil and the average species richness was 3.7 AM species per soil sample. There was no correlation between spore density and percentage root length colonized by AM fungi.     

A plethora of painful molecules

Pain is a fundamental experience with a complex and multi-layered neurobiological basis. In recent years a powerful battery of techniques has been brought to bear to unravel the mechanisms by which painful stimuli are transduced and processed. There have been several recent discoveries regarding the molecular transduction mechanisms in nociceptors and novel molecular and cellular mechanisms underlying the spinal processing of painful stimuli. The mechanisms by which sensory neurons initiate hyperalgesia and touch evoked pain (allodynia) have been addressed particularly successfully in recent studies. The rich variety of key molecular players that have emerged in physiological and pathophysiological pain states reflects the sophistication and uniqueness of this vitally important sense.     

Ligand modulates VDR-Ser/Thr protein phosphatase interaction and p70S6 kinase phosphorylation in a cell-context-dependent manner

We have recently shown that in colon cancer cells, Vitamin D receptor (VDR) interacts with the catalytic subunit of Ser/Thr protein phosphatases, PP1c and PP2Ac, and induces their enzymatic activity in a ligand-dependent manner. The VDR-PP1c and VDR-PP2Ac interactions were ligand independent in vivo, and 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3))-mediated increase in VDR-associated phosphatase activity resulted in dephosphorylation and inactivation of p70S6 kinase in colon cancer cells. Here, we demonstrate that in myeloid leukemia cells, 1,25(OH)(2)D(3) treatment increased the Thr389 phosphorylation of p70S6 kinase. Accordingly, 1,25(OH)(2)D(3) decreased VDR-associated Ser/Thr protein phosphatase activity by dissociating VDR-PP1c and VDR-PP2Ac interactions. Further, 1,25(OH)(2)D(3) increased the association between VDR and Thr389 phosphorylated p70S6 kinase. Finally, by using non-secosteroidal VDR ligands, we demonstrate a separation between transactivation and p70S6 kinase phosphorylation activities of VDR and show pharmacologically that p70S6 kinase phosphorylation correlates with HL-60 cell differentiation.     

Phosphorylation of p70s6 kinase is implicated in androgen-induced levator ani muscle anabolism in castrated rats

Androgens are known to increase muscle mass, strength and muscle protein synthesis. However, the molecular mechanisms by which androgens regulate skeletal muscle development remain poorly understood. The ribosomal protein kinase p70^s6k is a regulator of ribosome biogenesis and plays an important role in the regulation of growth-related protein synthesis. The phosphorylation of p70^s6k has been implicated in load-induced skeletal muscle hypertrophy. In the current study, we determined the effect of DHT on the phosphorylation of p70^s6k in the androgen-sensitive levator ani muscle of castrated rats. DHT induced a rapid increase in the phosphorylation of p70^s6k, which was detectable within 6 h after a single injection. Interestingly, DHT-induced phosphorylation of p70^s6k occurred only in androgen-sensitive muscles, but not prostate and seminal vesicle. Co-administration of flutamide, an AR antagonist, inhibited DHT-induced p70^s6k phosphorylation. While serum IGF-I levels were not changed by DHT treatment, IGF-I gene expression levels increased and the mRNA levels of IGFBP3 and IGFBP5 were suppressed in the LA muscle after DHT replacement in castrated rats. These results suggest that the phosphorylation of p70^s6k, likely via the IGF-I pathway, may play an important role in androgen-induced skeletal muscle hypertrophy.     

Dual functional roles of Tie-2/angiopoietin in TNF-alpha-mediated angiogenesis

Inflammation and angiogenesis are associated with pathological disorders. TNF-alpha is a major inflammatory cytokine that also regulates angiogenesis. TNF-alpha has been shown to regulate Tie-2 and angiopoietin (Ang) expression, but the functional significance is less clear. In this study, we showed that TNF-alpha induced a weak angiogenic response in a mouse cornea assay. Systemic overexpression of Ang-1 or Ang-2 dramatically increased corneal angiogenesis induced by TNF-alpha. In the absence of TNF-alpha, neither Ang-1 nor Ang-2 promoted corneal angiogenesis. Low doses (0-25 ng/ml) of TNF-alpha increased vascular branch formation of cultured endothelial cells. Overexpression of Ang-1 or Ang-2 enhanced the effects of TNF-alpha. These data suggest that Tie-2 signaling synergistically amplifies and participates in TNF-alpha-mediated angiogenesis. In addition, high doses (>/=50 ng/ml) of TNF-alpha induced apoptosis in endothelial cells, but addition of Ang-1 or Ang-2 significantly reduced cell death. Enhanced endothelial cell survival was correlated with Akt phosphorylation. Collectively, our data reveal dual functional roles of Tie-2: low doses enhance TNF-alpha-induced angiogenesis, and high doses attenuate TNF-alpha-induced cell death. The study provides evidence supporting a role for Tie-2 in inflammatory angiogenesis.