Alternative chaperone machinery may compensate for calreticulin/calnexin deficiency in Caenorhabditis elegans.
Proper folding and maintenance of the native structure are central to protein function and are assisted by a family of proteins called chaperones. Calreticulin and calnexin are ER resident chaperones well conserved from worm to human. Calreticulin/calnexin knock-out mice exhibit a severe phenotype, whereas in Caenorhabditis elegans, calreticulin [crt-1(jh101)]- and calnexin [cnx-1(nr2009)]-null mutant worms exhibit only a mild phenotype, suggesting the possible existence of alternative chaperone machinery that can compensate for the deficiency of calreticulin and/or calnexin. In order to rapidly identify the compensatory chaperone components involved in this process, we analyzed the proteome of crt-1(jh101) mutants and [crt-1(jh101);cnx-1(nr2009)] double mutants. When grown at 20 degrees C, we found that five proteins were up-regulated and two proteins were down-regulated in crt-1(jh101) mutants; nine proteins were up-regulated and five proteins were down-regulated in [crt-1(jh101);cnx-1(nr2009)] double mutants. In addition, elevation of the cultivation temperature to 25 degrees C, which is still permissive to growth but causes specific defects in mutants, led to the identification of several additional proteins. Interestingly, the consistent increment of heat shock protein-70 family members (hsp70) together with protein disulfide isomerase (PDI) at all the examined conditions suggests the possible compensatory function imparted by hsp70 and PDI family members in the absence of calreticulin and/or calnexin.
Lee
Wonhae
W
Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Korea.
Kim
Ki Ra
KR
Singaravelu
Gunasekaran
G
Park
Byung-Jae
BJ
Kim
Do Han
DH
Ahnn
Joohong
J
Yoo
Yung Joon
YJ
D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D037281:Calnexin / Q000172:deficiency*; D037282:Calreticulin / Q000172:deficiency*; D015180:Electrophoresis, Gel, Two-Dimensional; D004721:Endoplasmic Reticulum / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010449:Peptide Mapping; D019704:Protein Disulfide-Isomerases / Q000378:metabolism*; D040901:Proteomics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D037282:Calreticulin; D018840:HSP70 Heat-Shock Proteins; D037281:Calnexin; D019704:Protein Disulfide-Isomerases