Lin-28 homologue A (LIN28A) promotes cell cycle progression via regulation of cyclin-dependent kinase 2 (CDK2), cyclin D1 (CCND1), and cell division cycle 25 homolog A (CDC25A) expression in cancer

The RNA-binding protein LIN28A regulates the translation and stability of a large number of mRNAs as well as the biogenesis of certain miRNAs in embryonic stem cells and developing tissues. Increasing evidence indicates that LIN28A functions as an oncogene promoting cancer cell growth. However, little is known about its molecular mechanism of cell cycle regulation in cancer. Using tissue microarrays, we found that strong LIN28A expression was reactivated in about 10% (7.1-17.1%) of epithelial tumors (six tumor types, n = 369). Both in vitro and in vivo experiments demonstrate that LIN28A promotes cell cycle progression in cancer cells. Genome-wide RNA-IP-chip experiments indicate that LIN28A binds to thousands of mRNAs, including a large group of cell cycle regulatory mRNAs in cancer and embryonic stem cells. Furthermore, the ability of LIN28A to stimulate translation of LIN28A-binding mRNAs, such as CDK2, was validated in vitro and in vivo. Finally, using a combined gene expression microarray and bioinformatics approach, we found that LIN28A also regulates CCND1 and CDC25A expression and that this is mediated by inhibiting the biogenesis of let-7 miRNA. Taken together, these results demonstrate that LIN28A is reactivated in about 10% of epithelial tumors and promotes cell cycle progression by regulation of both mRNA translation (let-7-independent) and miRNA biogenesis (let-7-dependent).     

Conformational organizations of G-quadruplexes composed of d(G4Tn)3G4

Structural polymorphism is one of the important issues with regard to G-quadruplexes because the structural diversity may significantly affect their biological functions in vivo and their physical property in nano-material. A series of oligonucleotides with four repeat guanines sequence [d(G₄T_n)₃G₄ (n = 1–6)] were designed. In this study, the effects of loop length on the formation of structures of G-quadruplex were investigated through the result of CD (circular dichroism) and 20% non-denatured polyacrylamide gel electrophoresis. Our studies demonstrate that the length of loop in 100 mM KCl solution could predict the conformation of G-quadruplex.     

Synthesis and biological evaluation of nitric oxide releasing derivatives of 6-amino-3-n-butylphthalide as potential antiplatelet agents

A series of novel nitric oxide releasing derivatives of 6-amino-3-n-butylphthalide were designed, synthesized and evaluated as potential antiplatelet agents. Compound 10b significantly inhibited the adenosine diphosphate (ADP)-induced platelet aggregation in vitro, superior to 6-amino-3-n-butylphthalide, 3-n-butylphthalide (NBP) and ticlopidine. Meanwhile 10b released moderate levels of NO, which could be beneficial for improving cardiovascular and cerebral circulation. Furthermore, 10b had an enhanced aqueous solubility relative to NBP. These findings may provide new insights into the development of novel antiplatelet agents for the treatment of thrombosis-related ischemic stroke.     

Novel hybrids of natural isochroman-4-one bearing N-substituted isopropanolamine as potential antihypertensive candidates

A series of novel hybrids of natural isochroman-4-one bearing isopropanolamine moiety were designed, synthesized and evaluated for their antihypertensive activity. It was found that compound IIId, prepared by hybridizing N-isopropyl substituted isopropanolamine functionality to a phenolic oxygen of isochroman-4-one, exhibited potent β₁-adrenoceptor blocking effect comparable to the well-known antihypertensive drug propranolol. Additionally, IIId significantly reduced the systolic and diastolic blood pressure in SHRs by over 40%, which was obviously stronger than the lead compounds 7,8-dihydroxy-3-methyl-isochroman-4-one (XJP) and its analogue XJP-B. Overall, IIId may be a promising antihypertensive candidate for further investigation.     

N-WASp is required for Schwann cell cytoskeletal dynamics, normal myelin gene expression and peripheral nerve myelination

Schwann cells elaborate myelin sheaths around axons by spirally wrapping and compacting their plasma membranes. Although actin remodeling plays a crucial role in this process, the effectors that modulate the Schwann cell cytoskeleton are poorly defined. Here, we show that the actin cytoskeletal regulator, neural Wiskott-Aldrich syndrome protein (N-WASp), is upregulated in myelinating Schwann cells coincident with myelin elaboration. When N-WASp is conditionally deleted in Schwann cells at the onset of myelination, the cells continue to ensheath axons but fail to extend processes circumferentially to elaborate myelin. Myelin-related gene expression is also severely reduced in the N-WASp-deficient cells and in vitro process and lamellipodia formation are disrupted. Although affected mice demonstrate obvious motor deficits these do not appear to progress, the mutant animals achieving normal body weights and living to advanced age. Our observations demonstrate that N-WASp plays an essential role in Schwann cell maturation and myelin formation.