Planning your every move: the role of β-actin and its post-transcriptional regulation in cell motility.

Cell motility is a tightly regulated process that involves the polymerization of actin subunits. The formation of actin filaments is controlled through a variety of protein factors that accelerate or perturb the polymerization process. As is the case for most biological events, cell movement is also controlled at the level of gene expression.

Turnover of AU-rich-containing mRNAs during stress: a matter of survival.

Cells undergo various adaptive measures in response to stress. Among these are specific changes in the posttranscriptional regulation of various genes. In particular, the turnover of mRNA is modified to either increase or decrease the abundance of certain target messages.

Transportin 2 regulates apoptosis through the RNA-binding protein HuR.

In response to severe stress, apoptotic cell death is engaged. Apoptosis is a well orchestrated process that involves the activation and implication of many factors. In this study, we identified a role for the nuclear trafficking factor TRN2 (transportin 2) in cell death.

HuR and myogenesis: being in the right place at the right time.

The process of muscle cell differentiation into myotubes, termed myogenesis, depends on a complex coordination of myogenic factors, many of which are regulated post-transcriptionally. HuR, an mRNA-binding protein, is responsible for regulating the expression of several such myogenic factors by stabilizing their mRNAs. The critical role for HuR in myogenesis also involves the nucleocytoplasmic shuttling ability of this protein.

Protein kinase RNA/FADD/caspase-8 pathway mediates the proapoptotic activity of the RNA-binding protein human antigen R (HuR).

The RNA-binding protein human antigen R (HuR) has been implicated in apoptosis in multiple ways. Several studies have shown that in response to a variety of stresses HuR promotes the expression of proapoptotic mRNAs, whereas others reported its regulatory effect on antiapoptotic messages. We recently showed that in response to severe stress, HuR is cleaved to generate two cleavage products (CPs), HuR-CP1 (24 kDa) and HuR-CP2 (8 kDa), by which it promotes apoptotic cell death.

Decoding ARE-mediated decay: is microRNA part of the equation?

Messenger ribonucleic acids (mRNAs) containing adenine/uridine-rich elements (AREs) in their 3' untranslated region are particularly labile, allowing for the regulation of expression for growth factors, oncoproteins, and cytokines. The regulators, effectors, and location of ARE-mediated decay (AMD) have been investigated by many groups in recent years, and several links have been found between AMD and microRNA-mediated decay. We highlight these similarities, along with recent advances in the field of AMD, and also mention how there is still much left unknown surrounding this specialized mode of mRNA decay.

Caspase-mediated cleavage of HuR in the cytoplasm contributes to pp32/PHAP-I regulation of apoptosis.

The RNA-binding protein HuR affects cell fate by regulating the stability and/or the translation of messenger RNAs that encode cell stress response proteins. In this study, we delineate a novel regulatory mechanism by which HuR contributes to stress-induced cell death. Upon lethal stress, HuR translocates into the cytoplasm by a mechanism involving its association with the apoptosome activator pp32/PHAP-I.

The RNA-binding protein HuR promotes cell migration and cell invasion by stabilizing the beta-actin mRNA in a U-rich-element-dependent manner.

A high expression level of the beta-actin protein is required for important biological mechanisms, such as maintaining cell shape, growth, and motility. Although the elevated cellular level of the beta-actin protein is directly linked to the long half-life of its mRNA, the molecular mechanisms responsible for this effect are unknown. Here we show that the RNA-binding protein HuR stabilizes the beta-actin mRNA by associating with a uridine-rich element within its 3' untranslated region.