Cell-specific posttranslational events affect functional expression at the plasma membrane but not tetrodotoxin sensitivity of the rat brain IIA sodium channel α-subunit expressed in mammalian cells

The rat brain IIA Na⁺ channel alpha-subunit was expressed and studied in mammalian cells. Cells were infected with a recombinant vaccinia virus (VV) carrying the bacteriophage T7 RNA polymerase gene and were transfected with cDNA encoding the IIA Na⁺ channel α-subunit under control of a T7 promoter. Whole-cell patch-clamp recording showed that functional IIA channels were expressed efficiently (~10 channels/ µm² in approximately 60% of cells) in Chinese hamster ovary (CHO) cells and in neonatal rat ventricular myocytes but were expressed poorly in undifferentiated BC₃H1 cells and failed to express in Ltk⁻ cells. However, voltage-dependent Drosophila Shaker H4 K⁺ channels and Escherichia coli β-galactosidase were expressed efficiently in all four cell types with VV vectors. Because RNA synthesis probably occurs without major differences in the cytoplasm of all infected cell types under the control of the T7 promoter and T7 polymerase, we conclude that cell type-specific expression of the Na⁺ channel probably reflects differences at posttranslational steps. The gating properties of the IIA Na⁺ currents expressed in cardiac myocytes differed from those expressed in CHO cells; most noticeably, the IIA Na⁺ currents displayed more rapid macroscopic inactivation when expressed in cardiac myocytes. These differences also suggest cell- specific posttranslational modifications. IIA channels were blocked by ~90% by 90 nM TTX when expressed either in CHO cells or in cardiac myocytes; the latter also continued to display endogenous TTX- resistant Na⁺ currents. Therefore, the TTX binding site of the channel is not affected by cell-specific modifications and is encoded by the primary amino acid sequence

Norbinaltorphimine, a highly selective kappa-opioid antagonist in analgesic and receptor binding assays.

ABSTRAC

Gene expression profiles during in vivo human rhinovirus infection: insights into the host response. Am J Respir Crit Care Med

Rationale: Human rhinovirus infections cause colds and trigger exacerbations of lower airway diseases. Objectives: To define changes in gene expression profiles during in vivo rhinovirus infections. Methods: Nasal epithelial scrapings were obtained before and during experimental rhinovirus infection, and gene expression was evaluated by microarray. Naturally acquired rhinovirus infections, cultured human epithelial cells, and short interfering RNA knockdown were used to further evaluate the role of viperin in rhinovirus infections. Measurements and Main Results: Symptom scores and viral titers were measured in subjects inoculated with rhinovirus or sham control, and changes in gene expression were assessed 8 and 48 hours after inoculation. Real-time reverse transcription-polymerase chain reaction for viperin and rhinoviruses was used in naturally acquired infections, and viperin mRNA levels and viral titers were measure