VICKZ proteins mediate cell migration via their RNA binding activity

Abstract

The highly conserved, RNA binding VICKZ proteins help regulate RNA localization, stability, and translation in many eukaryotes. These proteins are also required for cell migration in embryos and cultured cells. In adults, many tumors overexpress VICKZ homologs, and it has been hypothesized that the proteins can mediate cell motility and invasion. How these proteins facilitate cell movement and, in particular, whether their ability to bind RNA plays a role in their function remain unclear. Using HPLC and mass spectrometry to identify a region of Xenopus Vg1 RBP (xVICKZ3) that binds the vegetal localization element of Vg1 RNA, we generated a deletion construct that functions in a dominant-negative manner. The construct associates with full-length xVICKZ3 and severely reduces binding to target RNAs. This dominant-negative construct phenocopies the effect of down-regulating xVICKZ3 in Xenopus embryos. A corresponding deletion in the human homolog hVICKZ1 similarly functions in a dominant-negative fashion to reduce the ability of full-length hVICKZ protein to bind RNA. Expression of the dominant-negative construct in human carcinoma cells inhibits cell movement by several criteria. We conclude that the ability of VICKZ proteins to mediate cell migration, in vitro and in vivo, requires their RNA binding activity.

Localization of cofilin mRNA to the leading edge of migrating cells promotes directed cell migration

“…S1B-D). These studies confirm and extend our previous findings (Oberman et al, 2007;Vainer et al, 2008) that hVICKZ1 helps mediate cell migration by influencing membrane dynamics. Furthermore, these results demonstrate that this assay can be used to quantitatively compare the effects of different constructs on membrane dynamics.…”

“…To more causally implicate VICKZ in cofilin mRNA localization, we then made use of a previously described hVICKZ1 deletion construct (termed hVICKZ1ΔKH4 or hVICKZ1-DN). This construct (lacking most of the KH4 RNA-binding domain) functions in a dominantnegative fashion to inhibit RNA binding of all the endogenous VICKZ paralogs (Oberman et al, 2007). When GFP-hVICKZ1-DN was introduced into H1299 cells by lentivirus infection, cofilin mRNA showed a localized pattern predominantly in those cells that did not express the exogenous GFP-labeled construct (Fig.…”

“…A number of studies have demonstrated the importance of VICKZ proteins in helping to regulate cell migration (Farina et al, 2003;Oberman et al, 2007;Vainer et al, 2008;Katz et al, 2012;Stöhr et al, 2012). Among the validated VICKZ target mRNAs are many that encode proteins involved in regulating β-actin polymerization at the leading edge of migrating cells (Gu et al, 2009;Gu et al, 2012).…”

“…The GFP viral plasmid had a PLKO backbone and was purchased from Sigma (SHCO14). For expression in cultured cells, sequences encoding GFP-hVICKZ1 and GFP-hVICKZ1-DN (Oberman et al, 2007) were cloned into a lentiviral backbone plasmid, a kind gift of Prof. Yinon Ben-Neriah (Hebrew University of Jerusalem). The MS2 coat protein plasmid with a pCDNA3.1+ backbone (Invitrogen) was a gift of the Shav-Tal laboratory.…”

Blocking β-catenin binding to the ZBP1 promoter represses ZBP1 expression, leading to increased proliferation and migration of metastatic breast-cancer cells

“…1B), suggesting that the ZBP1 gene in the metastatic cell lines could be transcriptionally repressed. Activation of ZBP1 expression has also been observed in breast tumors (Ioannidis et al, 2003a;Oberman et al, 2007;Yisraeli, 2005). To determine whether downregulation of ZBP1 expression occurred specifically in human breast metastatic tumors, we used a Cancer Profiling cDNA Array (BD Bioscience, catalog no.…”