Beta-actin mRNA localization is regulated by signal transduction mechanisms.

Abstract

A b s t r a c t . B-actin mRNA is localized in the leading lamellae of chicken embryo fibroblasts (CEFs) (Lawrence, J., and R. Singer. 1986. Cell. 45:407-415), close to where actin polymerization in the lamellipodia drives cellular motility. During serum starvation B-actin mRNA becomes diffuse and nonlocalized. Addition of FCS induces a rapid (within 2-5 min) redistribution of B-actin mRNA into the leading lamellae. A similar redistribution was seen with PDGF, a fibroblast chemotactic factor. PDGFinduced B-actin mRNA redistribution was inhibited by the tyrosine kinase inhibitor herbimycin, indicating that this process requires intact tyrosine kinase activity, similar to actin filament polymerization and chemotaxis. Lysophosphatidic acid, which has been shown to rapidly induce actin stress fiber formation (Ridley, A., and A. Hall. 1992. Cell. 790:389-399), also increases peripheral B-actin mRNA localization within minutes. This suggests that actin polymerization and mRNA localization may be regulated by similar signaling pathways. Additionally, activators or inhibitors of kinase A or C can also delocalize steady-state B-actin mRNA in cells grown in serum, and can inhibit the serum induction of peripherally localized B-actin mRNA in serum-starved CEFs. These data show that physiologically relevant extracellular factors operating through a signal transduction pathway can regulate spatial sites of actin protein synthesis, which may in turn affect cellular polarity and motility.

Polarized distribution of actin isoforms in gastric parietal cells.

“…The authors further showed that serum-induced 13-actin mRNA distribution is mediated through the GTPase signalling pathway. A similar conclusion was drawn by Singer's group in observing that PDGF-induced 1-actin mRNA was dependent on tyrosine kinase activity for redistribution in chicken embryo fibroblast and that the relocation of steady-state ,B-actin mRNA in serumcontaining media was inhibited by modulators of protein kinase A and C (Latham et al, 1994). These lines of evidence suggest that the signal transduction events modulate the dynamics of f-actin mRNA localization.…”

Myosin‐Va mediates RNA distribution in primary fibroblasts from multiple organs

“…While this does not demonstrate a direct interaction, it is consistent with the in situ hybridization data. Our data are particularly interesting in the context of the demonstration that myosin-IIB has been shown in fibroblasts to be required for the proper localization of β-actin mRNA in response to growth factors [Latham et al, 1994;Kislauskis et al, 1997;Latham et al, 2001]. From our pulse/chase experiments, myosin-Va appears to be responsible for mRNA transport from the nucleus to the periphery, where myosin-IIB could capture mRNAs.…”

Interactions of Elongation Factor 1α with F-Actin and β-Actin mRNA: Implications for Anchoring mRNA in Cell Protrusions

“…It is interesting to note that EF1␣ localizes with actin filaments in protrusions but not with stress fibers. In chicken fibroblasts, serum stimulation leads to rapid localization of ␤-actin mRNA at the cell front similar to EFI␣ (Latham et al, 1994). Electron microscopy studies have shown that EF1␣ molecules colocalize with mRNA on actin filaments (Bassell et al, 1994).…”

“…Furthermore, this inhibitory effect caused by expression of GFP-domain III is significant because localization of the ␤-actin mRNA in these cells was suppressed to almost background level represented by the localizations of ␣-tubulin mRNA in normally cultured CEFs and ␤-actin mRNA in CEFs in serum-depleted culture ( Figure 11A, lanes 5 and 6). Localization of ␤-actin mRNA has been known to depend on the presence of serum in cell culture (Latham et al 1994), whereas ␣-tubulin mRNA was shown not to localize in cells (Shestakova et al, 1999). …”