In neuronal development, dendritic outgrowth and arborization are important for the establishment of neural circuit formation. A previous study reported that PSD-95-interacting regulator of spine morphogenesis (Preso) formed a complex with PAK-interacting exchange factor-beta (βPix) via PSD-95/Dlg/ZO-1 (PDZ) interaction. Here, we report that Preso and its binding protein, βPix, are localized in dendritic growth cones. Knockdown and dominant-negative inhibition of Preso in cultured neurons markedly reduced the dendritic outgrowth but not branching, and led to a decrease in the intensity of βPix and F-actin in neuronal dendritic tips. Moreover, phosphatidylinositol 4,5-bisphosphate (PIP(2) ) induced a conformational change in Preso toward the open PDZ domain and enhanced the interaction with βPix. In addition, the Preso band 4.1 protein, ezrin, radixin and moesin (FERM) domain mutant is unable to interact with PIP(2) and it did not rescue the Preso-knockdown effect. These results indicate that PIP(2) is a key signalling molecule that regulates dendritic outgrowth through activation of small GTPase signalling via interaction between Preso and βPix.

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Poster abstractsthe current PP13 ELISA test and their existence can explain low levels of serum PP13 in women who subsequently develop preeclampsia. In this study we investigated the presence of circulating PP13 mRNA in pregnancies with physiological course of gestation. Methods: For the testing, we developed three various real-time RT-PCR systems (exon 1-2, exon 4, exon 4-UTR) for the detection of normal PP13 mRNA and for its shorter isoforms. The presence of PP13 mRNA was analysed in plasma samples of 16 women during the first and the third trimesters of gestation. Results: The systems were optimised to detect reliably 500, 50 and even 5 copies of placental-derived PP13 in a mixture with redundant PP13 negative RNA plasma sample derived from non-pregnant healthy individuals. However, the detection rate of PP13 mRNA in maternal plasma samples was substantially inconsistent (at the most one or two positive replicates out of 6 tested ones). Conclusions:The early detection of PP13 mRNA in maternal plasma does not represent a suitable method to predict later development of preeclampsia.

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