Valproic acid stimulates proliferation of glial precursors during cortical gliogenesis in developing rat

Valproic acid (VPA) is a neurotherapeutic drug prescribed for seizures, bipolar disorder, and migraine, including women of reproductive age. VPA is a well‐known teratogen that produces congenital malformations in many organs including the nervous system, as well as later neurodevelopmental disorders, including mental retardation and autism. In developing brain, few studies have examined VPA effects on glial cells, particularly astrocytes. To investigate effects on primary glial precursors, we developed new cell culture and in vivo models using frontal cerebral cortex of postnatal day (P2) rat. In vitro, VPA exposure elicited dose‐dependent, biphasic effects on DNA synthesis and proliferation. In vivo VPA (300 mg/kg) exposure from P2 to P4 increased both DNA synthesis and cell proliferation, affecting primarily astrocyte precursors, as >75% of mitotic cells expressed brain lipid‐binding protein. Significantly, the consequence of early VPA exposure was increased astrocytes, as both S100‐β+ cells and glial fibrillary acidic protein were increased in adolescent brain. Molecularly, VPA served as an HDAC inhibitor in vitro and in vivo as enhanced proliferation was accompanied by increased histone acetylation, whereas it elicited changes in culture in cell‐cycle regulators, including cyclin D1 and E, and cyclin‐dependent kinase (CDK) inhibitors, p21 and p27. Collectively, these data suggest clinically relevant VPA exposures stimulate glial precursor proliferation, though at higher doses can elicit inhibition through differential regulation of CDK inhibitors. Because changes in glial cell functions are proposed as mechanisms contributing to neuropsychiatric disorders, these observations suggest that VPA teratogenic actions may be mediated through changes in astrocyte generation during development. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 780–798, 2016     

New antiproliferative 7-(4-(N-substituted carbamoylmethyl)piperazin-1-yl) derivatives of ciprofloxacin induce cell cycle arrest at G2/M phase

New N-4-piperazinyl derivatives of ciprofloxacin 2a–g were prepared and tested for their cytotoxic activity. The primary in vitro one dose anticancer assay experienced promising cytotoxic activity against different cancer cell lines especially non-small cell lung cancer. Independently, compounds 2b, 2d, 2f and 2g showed anticancer activity against human non-small cell lung cancer A549 cells (IC₅₀ = 14.8, 24.8, 23.6 and 20.7 μM, respectively) compared to the parent ciprofloxacin (IC₅₀ >100 μM) and doxorubicin as a positive control (IC₅₀ = 1 μM). The flow cytometric analysis for 2b showed dose dependent G₂/M arrest in A549 cells. Also, 2b increased the expression of p53 and p21 and decreased the expression of cyclin B1 and Cdc2 proteins in A549 cells without any effect on the same proteins expression in WI-38 cells. Specific inhibition of p53 by pifithrin-α reversed the G₂/M phase arrest induced by the 2b compound, suggesting contribution of p53 to increase. Taken together, 2b induced G₂/M phase arrest via p53/p21 dependent pathway. The results indicate that 2b can be used as a lead compound for further development of new derivatives against non-small cell lung cancer.     

microRNA-222 Attenuates Mitochondrial Dysfunction During Transmissible Gastroenteritis Virus Infection

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Highlights

• •microRNA-222 attenuates TGEV-induced mitochondrial dysfunction.
• •microRNA-222 downregulates THBS1 and CD47.
• •THBS1 is the target of microRNA-222 during TGEV infection.
• •THBS1 and CD47 increase mitochondrial Ca²⁺ level and reduced mitochondrial membrane potential (MMP).

     

Haemophilus parasuis infection in 3D4/21 cells induces autophagy through the AMPK pathway

Haemophilus parasuis (H. parasuis) is a common commensal in the upper respiratory tract of pigs, but causes Glässer's disease in stress conditions. To date, many studies focused on the immune evasion and virulence of H. parasuis; very few have focused on the role autophagy played in H. parasuis infection, particularly in porcine alveolar macrophages (PAMs). In this study, a PAM cell line, 3D4/21 cells were used to study the role of autophagy in H. parasuis infection. 3D4/21 cells tandemly expressing GFP, mCherry, and LC3 were infected with H. parasuis serovar 5 (Hps5). Western blot analysis and confocal and transmission electron microscopy showed that H. parasuis infection effectively induces autophagy. Using Hps strains of varying virulence (Hps4, Hps5, and Hps7) and UV‐inactivated Hps5, we demonstrated that autophagy is associated with the internalisation of living virulent strains into cells. In 3D4/21 cells pretreated with rapamycin and 3‐MA then infected by Hps4, Hps5, and Hps7, we demonstrated that autophagy affects invasion of H. parasuis in cells. AMPK signal results showed that Hps5 infection can upregulate the phosphorylation level of AMPK, which is consistent with the autophagy development. 3D4/21 cells pretreated with AICAR or Compound C then infected by Hps5 revealed that the autophagy induced by Hps5 infection is associated with the AMPK pathway. Our study contributes to the theoretical basis for the study of H. parasuis pathogenesis and development of novel drugs target for prevention Glässer's disease.     

Role of phosphorylation on the structural dynamics and function of types III and IV intermediate filaments

Phosphorylation of types III and IV intermediate filaments (IFs) is known to regulate their organization and function. Phosphorylation of the amino-terminal head domain sites on types III and IV IF proteins plays a key role in the assembly/disassembly of IF subunits into 10 nm filaments, and influences the phosphorylation of sites on the carboxyl-terminal tail domain. These phosphorylation events are largely under the control of second messenger-dependent protein kinases and provide the cells a mechanism to reorganize the IFs in response to the changes in second messenger levels. In mitotic cells, Cdk1, Rho kinase, PAK1 and Aurora-B kinase are believed to regulate vimentin and glial fibrillary acidic protein phosphorylation in a spatio-temporal manner. In neurons, the carboxyl-terminal tail domains of the NF-M and NF-H subunits of heteropolymeric neurofilaments (NFs) are highly phosphorylated by proline-directed protein kinases. The phosphorylation of carboxyl-terminal tail domains of NFs has been suspected to play roles in forming cross-bridges between NFs and microtubules, slowing axonal transport and promoting their integration into cytoskeleton lattice and, in doing so, to control axonal caliber and stabilize the axon. The role of IF phosphorylation in disease pathobiology is discussed.     

Intrinsic Amyloidogenic Behavior of Terminally Protected Alzheimer’s Aβ<Superscript>17–21</Superscript> Peptide: Self-Aggregation and Amyloid-Like Fibril Formation

The terminally protected peptide Boc-Leu-Val-Phe-Phe-Ala-OMe bearing sequence similarity with the central hydrophobic cluster (CHC) of Alzheimer’s Aβ^17–21 peptide self-assembles to produce amyloid-like straight unbranched fibrils from organic solvents. The fibrils readily bind with a physiological dye Congo red (CR) and exhibits green gold birefringence under polarized light, a characteristic feature of amyloid plaque obtained from many neurodegenerative diseases. FTIR spectroscopy and in silico energy minimization study shed some light on the antiparallel supramolecular β-sheet aggregation of the peptide.