Ubiquitination and degradation of the zebrafish paired-like homeobox protein VSX-1.
Vsx-1 is a paired-like : CVC homeobox protein dynamically expressed during zebrafish development. Previous results indicate that Vsx-1 influences bipolar cell differentiation and maintenance of these cells in the adult retina. To understand the developmental regulation of this transcription factor, we investigated ubiquitination as a possible posttranslational mechanism. In vitro, Vsx-1 was conjugated with multiple ubiquitin moieties. Proteasome inhibitors and added ubiquitin increased the accumulation of Vsx-1-ubiquitin(n) complexes and stabilized unmodified Vsx-1. Also, in transiently transfected COS-7 cells, Vsx-1 is ubiquitinated, and pulse-chase experiments show that Vsx-1 proteolysis occurs. Vsx-1 proteins with C-terminal deletions retained the capacity for initial modification by ubiquitin but lost the capacity for efficient chain elongation. These results show that Vsx-1 is a substrate of the ubiquitin/proteasome pathway and suggest that C-terminal sequences of Vsx-1 are critical for ubiquitin chain elongation. In addition, our findings suggest that ubiquitin-dependent proteolysis regulates Vsx-1 during zebrafish retinal development.
Kurtzman
A L
AL
Department of Biochemistry, Health Sciences Center, Institute for Developmental Biology, State University of New York, Stony Brook, New York, USA.
Gregori
L
L
Haas
A L
AL
Schechter
N
N
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D019556:COS Cells; D003546:Cysteine Endopeptidases / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D011499:Protein Processing, Post-Translational; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D012160:Retina / Q000254:growth & development; D014162:Transfection; D014452:Ubiquitins / Q000378:metabolism*; D015027:Zebrafish; D029961:Zebrafish Proteins
D005136:Eye Proteins; D018398:Homeodomain Proteins; D009097:Multienzyme Complexes; D014452:Ubiquitins; D029961:Zebrafish Proteins; C108838:vsx1 protein, zebrafish; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases