Anti-DNMBP (aa 575-625) polyclonal antibody

Active Cdc42 GTPase, a key regulator of cell polarity, displays oscillatory dynamics that are anticorrelated at the two cell tips in fission yeast. Anticorrelation suggests competition for active Cdc42 or for its effectors. Here we show how 14-3-3 protein Rad24 associates with Cdc42 guanine exchange factor (GEF) Gef1, limiting Gef1 availability to promote Cdc42 activation. Phosphorylation of Gef1 by conserved NDR kinase Orb6 promotes Gef1 binding to Rad24. Loss of Rad24-Gef1 interaction increases Gef1 protein localization and Cdc42 activation at the cell tips and reduces the anticorrelation of active Cdc42 oscillations. Increased Cdc42 activation promotes precocious bipolar growth activation, bypassing the normal requirement for an intact microtubule cytoskeleton and for microtubule-dependent polarity landmark Tea4-PP1. Further, increased Cdc42 activation by Gef1 widens cell diameter and alters tip curvature, countering the effects of Cdc42 GTPase-activating protein Rga4. The respective levels of Gef1 and Rga4 proteins at the membrane define dynamically the growing area at each cell tip. Our findings show how the 14-3-3 protein Rad24 modulates the availability of Cdc42 GEF Gef1, a homologue of mammalian Cdc42 GEF DNMBP/TUBA, to spatially control Cdc42 GTPase activity and promote cell polarization and cell shape emergence.

Recent genome-wide screens have identified genes associated with the metastatic potential of hepatocellular carcinoma (HCC); however, there is little overlap between the identified genes, and interpretations of the results remain controversial. These inconsistencies may be related to differences in the sample populations, use of distinct microarray platforms and algorithms, and the complicated modes of HCC recurrence. We investigated the gene expression profiles of extrahepatic recurrence (EHR) and early intrahepatic recurrence (IHR), which are two representative modes of recurrence of HCC attributable to metastasis. We used DNA microarray analysis and identified 46 signature genes for EHR in 35 HCCs in a supervised learning manner. The obtained gene expression profile was compared with that for early IHR that was determined previously in the same manner. The 46 signature genes for EHR included many cell adhesion-related genes (ITGA6, SPP1, DNMBP, CD44 and POSTN), which all showed higher expression in HCC with EHR than in HCC without EHR. The 46 signature genes for early IHR included 10 immune response-related genes, which all showed lower expression in HCC with early IHR than in HCC without early IHR. The signature genes for EHR included only two immune response-related genes (P=0.013). These results suggest that alteration of the cell adhesion system plays a central role in EHR and that reduction of the immune response is a specific step in early IHR. These results indicate that the metastatic processes in EHR and early IHR involve different molecular pathways.