The actin-based cytoskeleton is essential for the generation and maintenance of cell polarity, cellular motility, and the formation of neural cell processes. MRP2 is an actin-binding protein of the kelch-related protein family. While MRP2 has been shown to be expressed specifically in brain, its function is still unknown. Here, we report that in neuronal growth factor (NGF)-induced PC12 cells, MRP2 was expressed along the neurite processes and colocalized with Talin at the growth cones. MRP2 mRNA and protein levels were up-regulated in PC12 cells following NGF stimulation. Moreover, treatment of PC12 cells with interfering RNAs for MRP2 and glycogen synthase kinase 3␤ (GSK3␤) resulted in the inhibition of neurite outgrowth. A significant decrease in MRP2 expression levels was observed following GSK3␤ inhibition, which was correlated with the inhibited neurite outgrowth, while GSK3␤ overexpression was found to increase MRP2 expression levels. MRP2 interacted with GSK3␤ through its NH 2 terminus containing the BTB domain, and these molecules colocalized along neurite processes and growth cones in differentiated PC12 cells and rat primary hippocampal neurons. Additionally, increased associations of MRP2 with GSK3␤ and MRP2 with actin were observed in the NGF-treated PC12 cells. Thus, this study provides, for the first time, insights into the involvement of MRP2 in neurite outgrowth, which occurs in a GSK3␤-dependent manner.Proliferation, differentiation, and morphogenesis are orchestrated by a variety of intracellular signals that are mediated by signal transduction cascades. In addition, nervous system function depends on the complex architecture of neuronal networks. The sprouting of neuronal outgrowth is an important characteristic in early neuronal differentiation. Neurogenesis begins immediately after neuronal commitment, with the activation of membrane receptors by extracellular cues subsequently activating intercellular cascades that trigger changes in the actin-based cytoskeleton. The actin-based cytoskeleton, together with microtubules and intermediate filaments, forms an internal framework which regulates the structure and function of cells and is responsible for the generation and maintenance of cell polarity and cellular motility (29).The actin-based cytoskeleton plays an important role in the formation of neural cell processes in developing neural tissues (38), is involved in controlling secretion from neurons (45), and also regulates gated channels (46). In response to extracellular signals, dynamic changes occur in the architecture of cells leading to alterations in cell morphology and gene expression (5, 40).Rearrangement of the actin-based cytoskeleton is regulated by a large number of actin-binding proteins (3, 41). A unique family of actin-binding proteins with sequences and structural domains homologous with the Drosophila kelch proteins has been identified (1, 3). The kelch-related proteins are believed to be important for the maintenance of the ordered cytoskeleton (12, 39); have diverse funct...

IntroductionPrevious studies suggest that multiple sclerosis (MS) patients have a greater stroke risk than the general population but there is limited evidence of stroke risk in patients receiving disease-modifying treatment. We assessed stroke risk in MS patients treated with subcutaneous interferon-β1a (sc IFN-β1a) using pooled data from clinical trials and post-marketing surveillance.MethodsSeventeen phase II–IV Merck KGaA-sponsored trials of sc IFN-β1a were assessed to estimate the stroke incidence rate (IR) and IR ratio (IRR) per 100 patient-years (PY), and associated 95% confidence intervals (CI). The association of treatment duration with stroke was assessed through a Cox model. IR, IRR, and hazard ratio (HR) were adjusted by age, sex, presence of any comorbidity, and MS duration. Individual case safety reports were retrieved from the Global Patient Safety Database. The reporting rates of stroke were calculated and classified as medically confirmed or non-medically confirmed according to the source of each report.ResultsIn 17 clinical trials, 4412 patients were treated with sc IFN-β1a for a total of 10,622 PY and 1055 patients with placebo for 2005 PY. The IR/100 PY (95% CI) of stroke was 0.025 (0.004, 0.150) in sc IFN-β1a patients and 0.051 (0.008, 0.349) in placebo patients. The IRR for sc IFN-β1a vs placebo was 0.486 (0.238, 0.995) and the HR was 0.496 (0.235, 1.043) for time to stroke-related event for sc IFN-β1a treatment at any dose compared with placebo. Among sc IFN-β1a patients, the IRR in those treated for < 2 years was 0.602 (0.159, 2.277) and for ≥ 2 years 0.469 (0.196, 1.124). Analysis of the safety database showed that the overall reporting rate for stroke was 13.286/10,000 PY.ConclusionSafety data from both clinical trial and post-marketing settings indicate that treatment with sc IFN-β1a does not increase stroke risk in patients with MS.FundingMerck KGaA, Darmstadt, Germany.