Abstract
RNA-binding proteins with intrinsically disordered regions (IDRs) such as Rbm14 can phase separate in vitro. To what extent the phase separation contributes to their physiological functions is however unclear. Here we show that zebrafish Rbm14 regulates embryonic dorsoventral patterning through phase separation. Zebrafish rbm14 morphants displayed dorsalized phenotypes associated with attenuated BMP signaling. Consistently, depletion of mammalian Rbm14 downregulated BMP regulators and effectors Nanog, Smad4/5, and Id1/2, whereas overexpression of the BMP-related proteins in the morphants significantly restored the developmental defects. Importantly, the IDR of zebrafish Rbm14 demixed into liquid droplets in vitro despite poor sequence conservation with its mammalian counterpart. While its phase separation mutants or IDR failed to rescue the morphants, its chimeric proteins containing an IDR from divergent phase separation proteins were effective. Rbm14 complexed with proteins involved in RNA metabolism and phase separated into cellular ribonucleoprotein compartments. Consistently, RNA deep sequencing analysis on the morphant embryos revealed increased alternative splicing events as well as large-scale transcriptomic downregulations. Our results suggest that Rbm14 functions in ribonucleoprotein compartments through phase separation to modulate multiple aspects of RNA metabolism. Furthermore, IDRs conserve in phase separation ability but not primary sequence and can be functionally interchangeable.
Highlights
Proteins containing intrinsically disordered regions (IDRs) including the prion-like domains (PLDs)[1] and the more general low complexity regions have been shown to demix or phase separate from their aqueous solutions into supramolecular condensates such as liquid droplets and hydrogels in vitro mainly in an aromatic amino acids-dependent manner[2,3,4,5,6,7]
Our results indicate that the IDR of zebrafish Rbm[14] can be functionally replaced in vivo by IDRs from other proteins known to undergo phase separation
Quantitative real-time PCR analyses showed that their mRNA levels were high in fertilized eggs but became concomitantly downregulated by >5-fold at the bud stage at 10 h post fertilization (Fig. 1a)[37]
Summary
Proteins containing intrinsically disordered regions (IDRs) including the prion-like domains (PLDs)[1] and the more general low complexity regions have been shown to demix or phase separate (or coacervate) from their aqueous solutions into supramolecular condensates such as liquid droplets and hydrogels in vitro mainly in an aromatic amino acids (especially Y residues)-dependent manner[2,3,4,5,6,7]. IDR-containing proteins display divergent phase separation properties, demixing at dramatically different critical concentrations and forming liquid droplets of varying dynamics and rigidity[7,8,9]. Systematic studies mainly on FUS further suggest that the intermolecular interactions between aromatic and basic amino acid residues (especially between Y and R) largely decide the critical concentration, whereas G, Q, and S residues contribute to physical properties[10]. These in vitro studies imply that coacervates formed by different IDRs exhibit
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
