Formation and Maturation of Phase-Separated Liquid Droplets by RNA-Binding Proteins

Yuan Lin; David S W Protter; Michael K Rosen; Roy Parker

doi:10.1016/j.molcel.2015.08.018

Formation and Maturation of Phase-Separated Liquid Droplets by RNA-Binding Proteins

Mol Cell. 2015 Oct 15;60(2):208-19. doi: 10.1016/j.molcel.2015.08.018. Epub 2015 Sep 24.

Authors

Yuan Lin¹, David S W Protter², Michael K Rosen³, Roy Parker⁴

Affiliations

¹ The HHMI Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA; Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
² The HHMI Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA; Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
³ The HHMI Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA; Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA. Electronic address: michael.rosen@utsouthwestern.edu.
⁴ The HHMI Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543, USA; Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA. Electronic address: roy.parker@colorado.edu.

Abstract

Eukaryotic cells possess numerous dynamic membrane-less organelles, RNP granules, enriched in RNA and RNA-binding proteins containing disordered regions. We demonstrate that the disordered regions of key RNP granule components and the full-length granule protein hnRNPA1 can phase separate in vitro, producing dynamic liquid droplets. Phase separation is promoted by low salt concentrations or RNA. Over time, the droplets mature to more stable states, as assessed by slowed fluorescence recovery after photobleaching and resistance to salt. Maturation often coincides with formation of fibrous structures. Different disordered domains can co-assemble into phase-separated droplets. These biophysical properties demonstrate a plausible mechanism by which interactions between disordered regions, coupled with RNA binding, could contribute to RNP granule assembly in vivo through promoting phase separation. Progression from dynamic liquids to stable fibers may be regulated to produce cellular structures with diverse physiochemical properties and functions. Misregulation could contribute to diseases involving aberrant RNA granules.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Amyloid / chemistry*
Amyloid / genetics
Amyloid / metabolism
Cytoplasmic Granules / chemistry
Cytoplasmic Granules / metabolism
Escherichia coli / genetics
Escherichia coli / metabolism
Fluorescence Recovery After Photobleaching
Gene Expression
Heterogeneous Nuclear Ribonucleoprotein A1
Heterogeneous-Nuclear Ribonucleoprotein Group A-B / chemistry*
Heterogeneous-Nuclear Ribonucleoprotein Group A-B / genetics
Heterogeneous-Nuclear Ribonucleoprotein Group A-B / metabolism
Humans
Intrinsically Disordered Proteins / chemistry*
Intrinsically Disordered Proteins / genetics
Intrinsically Disordered Proteins / metabolism
Molecular Mimicry
Organelles / chemistry*
Organelles / metabolism
Polyethylene Glycols / chemistry
Protein Aggregation, Pathological / genetics
Protein Aggregation, Pathological / metabolism
Protein Aggregation, Pathological / pathology
Protein Binding
Protein Structure, Tertiary
RNA / chemistry*
RNA / metabolism
Recombinant Proteins / chemistry
Recombinant Proteins / genetics
Recombinant Proteins / metabolism
Sodium Chloride / chemistry
Solutions

Substances

Amyloid
Heterogeneous Nuclear Ribonucleoprotein A1
Heterogeneous-Nuclear Ribonucleoprotein Group A-B
Intrinsically Disordered Proteins
Recombinant Proteins
Solutions
hnRNPA1 protein, human
Polyethylene Glycols
Sodium Chloride
RNA

Abstract

Publication types

MeSH terms

Substances

Grants and funding