| First Author | Rothé B | Year | 2015 |
| Journal | Mol Cell Biol | Volume | 35 |
| Issue | 19 | Pages | 3339-53 |
| PubMed ID | 26217012 | Mgi Jnum | J:228224 |
| Mgi Id | MGI:5705686 | Doi | 10.1128/MCB.00341-15 |
| Citation | Rothe B, et al. (2015) Bicc1 Polymerization Regulates the Localization and Silencing of Bound mRNA. Mol Cell Biol 35(19):3339-53 |
| abstractText | Loss of the RNA-binding protein Bicaudal-C (Bicc1) provokes renal and pancreatic cysts as well as ectopic Wnt/beta-catenin signaling during visceral left-right patterning. Renal cysts are linked to defective silencing of Bicc1 target mRNAs, including adenylate cyclase 6 (AC6). RNA binding of Bicc1 is mediated by N-terminal KH domains, whereas a C-terminal sterile alpha motif (SAM) self-polymerizes in vitro and localizes Bicc1 in cytoplasmic foci in vivo. To assess a role for multimerization in silencing, we conducted structure modeling and then mutated the SAM domain residues which in this model were predicted to polymerize Bicc1 in a left-handed helix. We show that a SAM-SAM interface concentrates Bicc1 in cytoplasmic clusters to specifically localize and silence bound mRNA. In addition, defective polymerization decreases Bicc1 stability and thus indirectly attenuates inhibition of Dishevelled 2 in the Wnt/beta-catenin pathway. Importantly, aberrant C-terminal extension of the SAM domain in bpk mutant Bicc1 phenocopied these defects. We conclude that polymerization is a novel disease-relevant mechanism both to stabilize Bicc1 and to present associated mRNAs in specific silencing platforms. |
