Highly Efficient Conversion of Motor Neuron-Like NSC-34 Cells into Functional Motor Neurons by Prostaglandin E2

Motor neuron diseases are a group of progressive neurological disorders that degenerate motor neurons. The neuroblastoma × spinal cord hybrid cell line NSC-34 is widely used as an experimental model in studies of motor neuron diseases. However, the differentiation efficiency of NSC-34 cells to neurons is not always sufficient. We have found that prostaglandin E2 (PGE2) induces morphological differentiation in NSC-34 cells. The present study investigated the functional properties of PGE2-differentiated NSC-34 cells. Retinoic acid (RA), a widely-used agent inducing cell differentiation, facilitated neuritogenesis, which peaked on day 7, whereas PGE2-induced neuritogenesis took only 2 days to reach the same level. Whole-cell patch-clamp recordings showed that the current threshold of PGE2-treated cell action potentials was lower than that of RA-treated cells. PGE2 and RA increased the protein expression levels of neuronal differentiation markers, microtubule-associated protein 2c and synaptophysin, and to the same extent, motor neuron-specific markers HB9 and Islet-1. On the other hand, protein levels of choline acetyltransferase and basal release of acetylcholine in PGE2-treated cells were higher than in RA-treated cells. These results suggest that PGE2 is a rapid and efficient differentiation-inducing factor for the preparation of functionally mature motor neurons from NSC-34 cells

<i>In Situ</i> Tuning of Magnetization and Magnetoresistance in Fe₃O₄ Thin Film Achieved with All-Solid-State Redox Device

An all-solid-state redox device composed of Fe₃O₄ thin film and Li⁺ ion conducting solid electrolyte was fabricated for use in tuning magnetization and magnetoresistance (MR), which are key factors in the creation of high-density magnetic storage devices. Electrical conductivity, magnetization, and MR were reversibly tuned by Li⁺ insertion and removal. Tuning of the various Fe₃O₄ thin film properties was achieved by donation of an electron to the Fe³⁺ ions. This technique should lead to the development of spintronics devices based on the reversible switching of magnetization and spin polarization (<i>P</i>). It should also improve the performance of conventional magnetic random access memory (MRAM) devices in which the ON/OFF ratio has been limited to a small value due to a decrease in <i>P</i> near the tunnel barrier