The Translation Repressor Smaug forms Stress Granule-like Foci.

MARÍA V. BAEZ; GRACIELA L. BOCCACCIO.

Pinamar, Argentina

Congreso; XLI reunión SAIB; 2005

SAIB

Cytoplasmic events depending on RNA binding proteins contribute to the fine-tuning of gene expression. Sterile Alpha Motif (SAM)-containing RNA binding proteins constitute a novel family of post-transcriptional regulators that recognize a specific RNA sequence motif known as Smaug Recognition Element (SRE). The Drosophila member of this family, dSmaug, triggers the translational repression and deadenylation of maternal mRNAs by independent mechanisms, and the yeast homologue Vts1 stimulates degradation of SRE-containing messengers. Two homologous genes are present in the mammalian genome. We found that hSmaug 1 represses the translation of reporter transcripts carrying SRE motifs. When expressed in fibroblasts, hSmaug 1 forms cytoplasmic granules that contain polyadenylated mRNA and stress-granule markers. The murine protein mSmaug 1 is expressed in the central nervous system and is abundant in post-synaptic densities, a subcellular region where translation is tightly regulated by synaptic stimulation. Biochemical analysis indicated that mSmaug 1 is present in synaptoneurosomal 20S particles. These results suggest a role for mammalian Smaug 1 in RNA granule formation and translation regulation in neurons.