SUMO regulates the assembly and function of a cytoplasmic intermediate filament protein in C. elegans.
Sumoylation is a reversible posttranslational modification that plays roles in many processes, including transcriptional regulation, cell division, chromosome integrity, and DNA damage response. Using a proteomics approach, we identified approximately 250 candidate targets of sumoylation in C. elegans. One such target is the cytoplasmic intermediate filament (cIF) protein named IFB-1, which is expressed in hemidesmosome-like structures in the worm epidermis and is essential for embryonic elongation and maintenance of muscle attachment to the cuticle. In the absence of SUMO, IFB-1 formed ectopic filaments and protein aggregates in the lateral epidermis. Moreover, depletion of SUMO or mutation of the SUMO acceptor site on IFB-1 resulted in a reduction of its cytoplasmic soluble pool, leading to a decrease in its exchange rate within epidermal attachment structures. These observations indicate that SUMO regulates cIF assembly by maintaining a cytoplasmic pool of nonpolymerized IFB-1, and that this is necessary for normal IFB-1 function.
Kaminsky
Rachel
R
Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
Denison
Carilee
C
Bening-Abu-Shach
Ulrike
U
Chisholm
Andrew D
AD
Gygi
Steven P
SP
Broday
Limor
L
D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D007381:Intermediate Filament Proteins / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding; D040901:Proteomics; D025841:Small Ubiquitin-Related Modifier Proteins / Q000235:genetics / Q000378:metabolism*
D029742:Caenorhabditis elegans Proteins; C545435:IFB-1 protein, C elegans; D007381:Intermediate Filament Proteins; D025841:Small Ubiquitin-Related Modifier Proteins