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Kringle 5, derived from plasminogen, is highly capable of inhibiting angiogenesis. Here, we have designed and synthesized 10 tetrapeptides, based on the amino acid properties of the core tetrapeptide Lys-Leu-Tyr-Asp (KLYD) originating from anti-angiogenic kringle 5 of human plasminogen. Of these, Arg-Leu-Tyr-Glu (RLYE) effectively inhibited vascular endothelial growth factor (VEGF)-induced endothelial cell proliferation, migration and tube formation, with an IC 50 of 0.06–0.08 nM, which was about ten-fold lower than that of the control peptide KLYD (0.79 nM), as well as suppressed developmental angiogenesis in a zebrafish model. Furthermore, this peptide effectively inhibited the cellular events that precede angiogenesis, such as ERK and eNOS phosphorylation and nitric oxide production, in endothelial cells stimulated with VEGF. Collectively, these data demonstrate that RLYE is a potent anti-angiogenic peptide that targets the VEGF signaling pathway. [ABSTRACT FROM AUTHOR]

Abstract: Mg2+ is one of the most important cations in cells, affecting the structures and functions of the proteins and nucleic acids. It should be noted that Mg2+ is indispensable in DNA transcription, where G-quadruplex is believed to be actively involved. Therefore, it is important to investigate the influence of Mg2+ on G-quadruplex. Here we studied the effect of Mg2+ on G-quadruplex DNA with CD, FRET, EMSA, and PCR-stop assay. We found that various G-quadruplexes could be differentiated through simultaneous addition of both K+ and Mg2+, which could be used for selective identification of G-quadruplexes in promoter oncogene but not in telomere. Mg2+ at physiological relevant concentration not only greatly enhanced the thermostability of oncogene G-quadruplexes but also efficiently protected them from unfolding by their complementary strands, which revealed the great impact of Mg2+ on the equilibrium between promoter G-quadruplex and duplex DNA. The PCR-stop assay further confirmed that Mg2+ could affect gene transcription by stabilizing promoter G-quadruplex. The above studies were carried out for various G-quadruplexes of varying sequences in promoter oncogenes and telomeric region. Our results suggest that Mg2+ may be a key regulator for G-quadruplexes of oncogene promoter, which can subsequently affect the expression of related genes. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO), derived by the enzymatic reaction of heme oxygenase (HO), is a cellular regulator of energy metabolism and cytoprotection; however, its underlying mechanism has not been clearly elucidated. Astrocytes pre-exposed to the CO-releasing compound CORM-2 increased mitochondrial biogenesis, mitochondrial electron transport components (cytochrome c, Cyt c ; cytochrome c oxidase subunit 2, COX2), and ATP synthesis. The increased mitochondrial function was correlated with activation of AMP-activated protein kinase α and upregulation of HO-1, peroxisome proliferators-activated receptor γ-coactivator-1α (PGC-1α), and estrogen-related receptor α (ERRα). These events elicited by CORM-2 were suppressed by Ca 2+ chelators, a HO inhibitor, and an L-type Ca 2+ channel blocker, but not other Ca 2+ channel inhibitors. Among the HO byproducts, combined CORM-2 and bilirubin treatment effectively increased PGC-1α, Cyt c and COX2 expression, mitochondrial biogenesis, and ATP synthesis, and these increases were blocked by Ca 2+ chelators. Moreover, cerebral ischemia significantly increased HO-1, PGC-1α, and ERRα levels, subsequently increasing Cyt c and COX2 expression, in wild-type mice, compared with HO-1 +/− mice. These results suggest that HO-1-derived CO enhances mitochondrial biogenesis in astrocytes by activating L-type Ca 2+ channel-mediated PGC-1α/ERRα axis, leading to maintenance of astrocyte function and neuroprotection/recovery against damage of brain function. [ABSTRACT FROM AUTHOR]

Abstract: The tumor suppressor p53 is pivotal in cell growth arrest and apoptosis upon cellular stresses including DNA damage. Mounting evidence indicates that p63 proteins, which are homologs of p53, are also involved in apoptosis under certain circumstances. In this study, we found that treatment with DNA damage agents leads to down-regulation of ΔNp63α and induces apoptosis in FaDu and HaCat cells carrying mutant p53. Further study shows that DNA damage reduces steady-state mRNA level of ΔNp63α, but has little effect on its protein stability. In addition, knockdown of endogenous ΔNp63α directly induces apoptosis and sensitizes cells to DNA damage, while exogenous expression of ΔNp63α partially confers cellular resistance to DNA damage. Together, these data suggest that DNA damage down-regulates ΔNp63α, which may directly contribute to DNA damage-induced apoptosis. [Copyright &y& Elsevier]

Abstract: The C-5-methylation of cytosine in the CpG islands is an important pattern for epigenetic modification of gene, which plays a key role in regulating gene transcription. G-quadruplex is an unusual DNA secondary structure formed in G-rich regions and is identified as a transcription repressor in some oncogenes, such as c-myc and bcl-2. In the present study, the results from CD spectrum and FRET assay showed that the methylation of cytosine in the CpG islands could induce a conformational change of the G-quadruplex in the P1 promoter of bcl-2, and greatly increase the thermal-stability of this DNA oligomer. Moreover, the methylation of cytosine in the G-quadruplex could protect the structure from the disruption by the complementary strand, showing with the increasing ability to arrest the polymerase in PCR stop assay. This data indicated that the stabilization of the G-quadruplex structure in the CpG islands might be involved in the epigenetical transcriptional regulation for specific genes through the C-5-methylation modification pattern. [Copyright &y& Elsevier]