PLD1 as a mediator of neuronal precusor cells differentiation pathway

Abstract

PLD is expressed in diverse brain areas, including olfactory bulb, medial septum-diagonal band complex, cerebral cortex, brainstem, cerebellar Purkinje cells, and spinal cord. It appears to play roles in a wide variety of cellular signaling pathways, membrane vesicle trafficking, and exocytosis. And it is also involved in membrane dynamics through actin-based membrane ruffles. Employing neuronal precusor cells from the brain cortex of E14 rat embryos, we studied the possible role of phospholipase D in neurite formation. Expression level of PLD1 increased during neuronal differentiation. Bcl-2 and hippocalcin ,which were defined to have a critical role in neurite outgrowing in H19-7 cells from our previous data, also rised in expression level during neural differentiation. To investigate whether PLD1 is involved in neuronal differentiation of rat neuronal precusor cells, the cells were infected with EGFP-rPLD1 or EGFP-DNPLD1: PLD1 overexpression results in a positive effect on neurite formation and increased the expression level of Bcl-2. Contrastly, PLD1 knockdown by DN-PLD1 transfection showed inhibited neurite outgrowth and downregulation of bcl2 expression. we found PLCγ, JNK, and CREB acted on the downstream of PLD, although the relation among them remains to solve. Besides, effects of Bcl-2 or hippocalcin on neurogenesis were tested through investigating PCR products of neurotrophic factors (NF) or/and NF receptors. Especially, hippocalcin showed a synergistic effect on NT4/5 expression with PLD. In summary, even though there are questions to be defined, the findings provide novel insights into the molecular mechanism of PLD on neuronal differentiation.