Acta Academiae Medicinae Sinica

Acta Academiae Medicinae Sinica

Acta Academiae Medicinae Sinica ›› 2009, Vol. 31 ›› Issue (6): 735-739.doi: 10.3881/j.issn.1000-503X.2009.06.017

• Original Articles • Previous Articles     Next Articles

Nuclear Localization of Insulin-like Growth Factor Binding Protein-6

HAN Jian-jun; HUANG Bing-ren;WANG Xin;MA Xiao-li; CHEN Hong   

  1. National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences,CAMS and PUMC,Beijing 100005, China
  • Received:2009-09-08 Revised:1900-01-01 Online:2009-12-30 Published:2009-12-30
  • Contact: CHEN Hong

Abstract: ABSTRACT:Objective To study the nuclear localization of insulin-like growth factor binding protein-6(IGFBP-6) in PC-3M cells. Methods The two fragments of the nuclear localization sequence (NLS)-deleted IGFBP-6 and the NLS-mutated IGFBP-6 were obtained by overlapping PCR, and then the fragment was inserted into a pEGFP-C1 vector. PC-3M cells were transfected with the expression constructs containing wild-type IGFBP-6 or the two mutants (pEGFP-C1-BP6ΔNLS and pEGFP-C1-BP6-Mut), and the different distribution of the three EGFP-fusion proteins was observed by confocal laser microscope. The statistical analysis of the ratio of the nuclear fluorescence to the cytoplasmic fluorescence (Fn/c) was performed. Results Confocal microscopic images of transfected cells showed that the green fluorescence of EGFP-IGFBP-6 was concentrated mostly in the nuclei, whereas the control cells expressing EGFP showed green fluorescence distributed uniformly. The results of Fn/c from EGFP and EGFP-IGFBP-6 were significant different (P<0.05). The NLS-deleted IGFBP-6 completely eliminated nuclear accumulation of the green fluorescent signal; in contrast, nuclear accumulation was only slightly reduced for the NLS-mutated IGFBP-6; compared with wild-type IGFBP-6, both mutants were significantly different (P<0.05). Conclusions IGFBP-6 can be translocated to the nucleus in PC-3M cell that is mediated by a putative NLS sequence. Our study provides new evidence for further studies on the insulin-like growth factor-independent activity of IGFBP-6.

Key words: insulin-like crowtd factor bindinc protein-6, nuclear localization, nuclear localization sequence, insulin-like crowtd factor-independent activity