Secreted CREG inhibits cell proliferation mediated by mannose 6-phosphate/insulin-like growth factor II receptor in NIH3T3 fibroblasts.
Cellular repressor of E1A-stimulated genes (CREG) is a recently described glycoprotein that plays a critical role in keeping cells or tissues in mature, homeostatic states. To understand the relationship between CREG and its membrane receptor, mannose 6-phosphate/insulin-like growth factor II receptor (M6P/IGF2R), we first generated stable NIH3T3 fibroblasts by transfection of pDS_shCREGs vectors, which produced an approximately 80% decrease in CREG levels both in the lysate and in the media. We used fluorescence activated cell sorting and a bromide deoxyuridine incorporation assay to identify whether CREG knockdown promoted the cell proliferation associated with the increase of IGF-II in NIH3T3 fibroblasts. Proliferation was markedly inhibited in a concentration-dependent manner by re-addition of recombinant CREG protein into the media, and this was mediated by the membrane receptor M6P/IGF2R. We subsequently confirmed the direct interaction of CREG and M6P/IGF2R by both immunoprecipitation-Western blotting and immunofluorescence staining. We found that expression of CREG correlated with localization of the receptor in NIH3T3 fibroblasts but did not affect its expression. Our findings indicated that CREG might act as a functional regulator of M6P/IGF2R to facilitate binding and trafficking of IGF-II endocytosis, leading to growth inhibition.
Han
Ya-Ling
YL
Department of Cardiology, Cardiovascular Research Institute, Shenyang Northern Hospital, Shenyang, China. hanyaling@263.net
Guo
Peng
P
Sun
Ming-Yu
MY
Guo
Liang
L
Luan
Bo
B
Kang
Jian
J
Yan
Cheng-Hui
CH
Li
Shao-Hua
SH
D000818:Animals; D049109:Cell Proliferation; D003470:Culture Media / Q000737:chemistry; D005347:Fibroblasts / Q000378:metabolism; D005822:Genetic Vectors; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008360:Mannosephosphates; D051379:Mice; D041681:NIH 3T3 Cells; D017527:Receptor, IGF Type 2 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
C485248:Creg protein, mouse; D003470:Culture Media; D006023:Glycoproteins; D008360:Mannosephosphates; D017527:Receptor, IGF Type 2; D011994:Recombinant Proteins; D012097:Repressor Proteins; C027693:mannose-6-phosphate