Dataset Information

ARAP1 regulates the ring size of circular dorsal ruffles through Arf1 and Arf5.

ABSTRACT: Small guanosine triphosphatase (GTPase) ADP-ribosylation factors (Arfs) regulate membrane traffic and actin reorganization under the strict control of GTPase-activating proteins (GAPs). ARAP1 (Arf GAP with Rho GAP domain, ankyrin repeat, and PH domain 1) is an Arf GAP molecule with multiple PH domains that recognize phosphatidylinositol 3,4,5-trisphosphate. We found that growth factor stimulation induced localization of ARAP1 to an area of the plasma membrane inside the ring structure of circular dorsal ruffles (CDRs). Moreover, expression of ARAP1 increased the size of the CDR filamentous-actin ring in an Arf GAP activity-dependent manner, whereas smaller CDRs were formed by ARAP1 knockdown. In addition, expression of a dominant-negative mutant of Arf1 and Arf5, the substrates of ARAP1, expanded the size of CDRs, suggesting that the two Arf isoforms regulate ring structure downstream of ARAP1. Therefore our results reveal a novel molecular mechanism of CDR ring size control through the ARAP1-Arf1/5 pathway.

SUBMITTER: Hasegawa J

PROVIDER: S-EPMC3386212 | biostudies-literature | 2012 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

ARAP1 regulates the ring size of circular dorsal ruffles through Arf1 and Arf5.

Hasegawa Junya J Tsujita Kazuya K Takenawa Tadaomi T Itoh Toshiki T

Molecular biology of the cell 20120509 13

Small guanosine triphosphatase (GTPase) ADP-ribosylation factors (Arfs) regulate membrane traffic and actin reorganization under the strict control of GTPase-activating proteins (GAPs). ARAP1 (Arf GAP with Rho GAP domain, ankyrin repeat, and PH domain 1) is an Arf GAP molecule with multiple PH domains that recognize phosphatidylinositol 3,4,5-trisphosphate. We found that growth factor stimulation induced localization of ARAP1 to an area of the plasma membrane inside the ring structure of circula ...[more]

PMID: 22573888

Similar Datasets

Project description:BackgroundCircular dorsal ruffles (CDRs) are rounded membrane ruffles induced on the dorsal surfaces of cells stimulated by growth factors (GF). They can serve as signal platforms to activate AKT protein kinase. After GF stimulation, phosphatidylinositol 3-kinase (PI3K) generates phosphatidylinositol (3,4,5)-triphosphate (PIP3) in the plasma membrane. PIP3 accumulates inside CDRs, recruits AKT into the structures, and phosphorylates them (pAKT). Given the importance of the PI3K-AKT pathway in GF signaling, CDRs are likely involved in cell growth. Interestingly, some cancer cell lines express CDRs. We hypothesized that CDRs contribute to carcinogenesis by modulating the AKT pathway. In the present study, we identified CDR-expressing cancer cell lines and investigated their cellular functions.MethodsCDR formation was examined in six cancer cell lines in response to epidermal growth factor (EGF) and insulin. The morphology of the CDRs was characterized, and the related signaling molecules were observed using confocal and scanning electron microscopy. The role of CDRs in the AKT pathway was studied using biochemical analysis. The actin inhibitor cytochalasin D (Cyto D) and the PI3K inhibitor TGX221 were used to block CDRs.ResultsGF treatment induced CDRs in the hepatocellular carcinoma (HCC) Hep3B cell line, but not in others, including HCC cell lines HepG2 and Huh7, and the LO2 hepatocyte cell line. Confocal microscopy and western blot analysis showed that the PI3K-PIP3-AKT pathway was activated at the CDRs and that receptor proteins were recruited to the structures. Cyto D and TGX221 completely blocked CDRs and partially attenuated GF-induced pAKT. These results indicate that CDRs regulate the receptor-mediated PI3K-AKT pathway in Hep3B cells and the existence of CDR-independent pAKT mechanisms.ConclusionsOur results showed that CDRs modulate the AKT pathway in Hep3B cells. Since CDRs were not observed in other HCC and hepatocyte cell lines, we propose that CDRs in Hep3B would determine the carcinoma characteristic of the cell by aberrantly triggering the AKT pathway. Signaling molecules involved in CDR formation are promising therapeutic targets for some types of HCC. Video abstract.

Dataset Information

ARAP1 regulates the ring size of circular dorsal ruffles through Arf1 and Arf5.

Publications

ARAP1 regulates the ring size of circular dorsal ruffles through Arf1 and Arf5.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets