ASAP3 Is a Focal Adhesion-associated Arf GAP That Functions in Cell Migration and Invasion

Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Journal of Biological Chemistry (Impact Factor: 4.57). 06/2008; 283(22):14915-26. DOI: 10.1074/jbc.M709717200
Source: PubMed


ASAP3, an Arf GTPase-activating protein previously called DDEFL1 and ACAP4, has been implicated in the pathogenesis of hepatocellular
carcinoma. We have examined in vitro and in vivo functions of ASAP3 and compared it to the related Arf GAP ASAP1 that has also been implicated in oncogenesis. ASAP3 was biochemically
similar to ASAP1: the pleckstrin homology domain affected function of the catalytic domain by more than 100-fold; catalysis
was stimulated by phosphatidylinositol 4,5-bisphosphate; and Arf1, Arf5, and Arf6 were used as substrates in vitro. Like ASAP1, ASAP3 associated with focal adhesions and circular dorsal ruffles. Different than ASAP1, ASAP3 did not localize
to invadopodia or podosomes. Cells, derived from a mammary carcinoma and from a glioblastoma, with reduced ASAP3 expression
had fewer actin stress fiber, reduced levels of phosphomyosin, and migrated more slowly than control cells. Reducing ASAP3
expression also slowed invasion of mammary carcinoma cells. In contrast, reduction of ASAP1 expression had no effect on migration
or invasion. We propose that ASAP3 functions nonredundantly with ASAP1 to control cell movement and may have a role in cancer
cell invasion. In comparing ASAP1 and ASAP3, we also found that invadopodia are dispensable for the invasive behavior of cells
derived from a mammary carcinoma.

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Available from: Armand de Gramont, Jan 04, 2016
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    • "These kinases were chosen because (1) their endogenous activity can be both induced and inhibited pharmacologically and (2) the phosphorylation of their substrates can be readily detected using commercially available antibodies. For instance, in the first round of validation experiments, we observed that DDEFL1/ASAP3, a GTPase activating protein involved in cell differentiation and migration (Ha et al, 2008), underwent a PKC-dependent increase in its protein levels (Figure 2B, top panel). "
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    • "ASAP3, which is closely related to ASAP1, is associated with focal adhesions and circular dorsal ruffles, but is not localized to podosomes [55]. The reduction of ASAP3 expression results in fewer actin stress fibers, reduced levels of phosphorylated myosin, and slower cell migration and invasion. "
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    • "Thus, we wanted to investigate if calcium can have an additive effect in such a scenario. GTPase activity measurements of membrane-bound ASAP3 and Arf have been done with liposomes containing phosphatidylserine (PS), phosphatidylinositol (PI), and PI(4,5)P 2 (Ha et al., 2008). Unfortunately, PI and PS bind divalent cations such as calcium, sequestering them from solution and aggregating the liposomes (Fraley et al., 1980; Janmey et al., 1987). "

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