Overexpression of ERp29 in the thyrocytes of FRTL-5 cells.
It was previously reported that the up-regulation of ERp29 mRNA depends on the levels of thyroid stimulating hormone (TSH) in the thyrocytes of FRTL-5 cells. In order to investigate the putative new function of ERp29 as an endoplasmic molecular (ER) chaperone, an ERp29-overexpressing FRTL-5 cell line was established. This cell line had approximately three times the levels of ERp29 protein and an enhanced level of thyroglobulin (Tg) secretion. The results showed both enhanced ERp29 expression and an interaction with the other ER chaperones such as GRP94, BiP, ERp72 and calnexin. In addition, ERp29 enhanced the expression of PKR-like ER kinase (PERK), which is a transmembrane protein located in the ER membrane. These findings suggest that ERp29 assists in protein folding as well as in the secretion of the secretory/plasma membrane proteins under close co-operation with other ER chaperones and the ER stress signaler, PERK.
Park
Soojung
S
Department of Anatomy, Chungnam National University, Taejon 301-747, Korea.
You
Kwan-Hee
KH
Shong
Minho
M
Goo
Tae Won
TW
Yun
Eun Young
EY
Kang
Seok Woo
SW
Kwon
O-Yu
OY
D000818:Animals; D037281:Calnexin / Q000378:metabolism; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding; D021381:Protein Transport; D051381:Rats; D013954:Thyroglobulin / Q000378:metabolism*; D013961:Thyroid Gland / Q000166:cytology / Q000378:metabolism*; D015533:Transcriptional Activation; D019892:eIF-2 Kinase / Q000378:metabolism
D037281:Calnexin; D000091342:Endoplasmic Reticulum Chaperone BiP; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D013954:Thyroglobulin; D019892:eIF-2 Kinase; C110909:Erp29 protein, rat; C062477:endoplasmic reticulum glycoprotein p72; C018551:glucose-regulated proteins