Asymmetric enrichment of PIE-1 in the Caenorhabditis elegans zygote mediated by binary counterdiffusion.
To generate cellular diversity in developing organisms while simultaneously maintaining the developmental potential of the germline, germ cells must be able to preferentially endow germline daughter cells with a cytoplasmic portion containing specialized cell fate determinants not inherited by somatic cells. In Caenorhabditis elegans, germline inheritance of the protein PIE-1 is accomplished by first asymmetrically localizing the protein to the germplasm before cleavage and subsequently degrading residual levels of the protein in the somatic cytoplasm after cleavage. Despite its critical involvement in cell fate determination, the enrichment of germline determinants remains poorly understood. Here, combining live-cell fluorescence methods and kinetic modeling, we demonstrate that the enrichment process does not involve protein immobilization, intracellular compartmentalization, or localized protein degradation. Instead, our results support a heterogeneous reaction/diffusion model for PIE-1 enrichment in which the diffusion coefficient of PIE-1 is reversibly reduced in the posterior, resulting in a stable protein gradient across the zygote at steady state.
Daniels
Brian R
BR
Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA.
Perkins
Edward M
EM
Dobrowsky
Terrence M
TM
Sun
Sean X
SX
Wirtz
Denis
D
D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D005854:Germ Cells / Q000737:chemistry / Q000166:cytology; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009687:Nuclear Proteins / Q000378:metabolism*; D015053:Zygote / Q000737:chemistry / Q000166:cytology / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D009687:Nuclear Proteins; C100950:pie-1 protein, C elegans