Sending messages in moving cells: mRNA localization and the regulation of cell migration

Cell migration is a fundamental biological process involved in tissue formation
and homeostasis. The correct polarization of motile cells is critical to ensure
directed movement and is orchestrated by many intrinsic and extrinsic factors.
Of these, the subcellular distribution of mRNAs and the consequent spatial
control of translation are key modulators of cell polarity. mRNA transport is
dependent on cis-regulatory elements within transcripts, which are recognized
by trans-acting proteins that ensure the efficient delivery of certain messages to
leading cell edge of migrating cells. At their destination, translation of localized
mRNAs then participates in regional cellular responses underlying cell motility.
In this review, we summarize the key findings that established mRNA targeting
as a critical driver of cell migration and how the characterization of polarized
mRNAs in motile cells has been expanded from just a few species to hundreds
of transcripts. We also describe the molecular control of mRNA trafficking,
subsequent mechanisms of local protein synthesis and how these ultimately
regulate cell polarity during migration.