Format

Send to

Choose Destination
J Hepatol. 2011 Sep;55(3):626-635. doi: 10.1016/j.jhep.2010.12.022. Epub 2011 Jan 13.

Nucleoplasmic calcium regulates cell proliferation through legumain.

Author information

1
Department of Biochemistry and Immunology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
2
Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA; Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.
3
Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
4
Department of Genetics, Center for Cell Based Therapy, University of São Paulo, Ribeirão Preto, SP, Brazil.
5
Department of Pathology, Yale University School of Medicine, New Haven, CT, USA.
6
Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA; Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA. Electronic address: michael.nathanson@yale.edu.

Abstract

BACKGROUND & AIMS:

Nucleoplasmic Ca(2+) regulates cell growth in the liver, but the proteins through which this occurs are unknown.

METHODS:

We used Rapid Subtraction Hybridization (RaSH) to subtract genes in SKHep1 liver cells expressing the Ca(2+) buffer protein parvalbumin (PV) targeted to the nucleus, from genes in cells expressing a mutated form of nuclear-targeted PV which has one of two Ca(2+)-binding sites inactivated. The subtraction permitted the selection of genes whose expression was affected by a small alteration in nuclear Ca(2+) concentration.

RESULTS:

The asparaginyl endopeptidase legumain (LGMN) was identified in this screening. When Ca(2+) was buffered in the nucleus of SKHep1 cells, LGMN mRNA was decreased by 97%, in part by a transcriptional mechanism, and decreased expression at the protein level was observed by immunoblot and immunofluorescence. Treatment with hepatocyte growth factor increased LGMN expression. Knockdown of LGMN by siRNA decreased proliferation of SKHep1 cells by ∼50% as measured both by BrdU uptake and mitotic index, although an inhibitor of LGMN activity did not affect BrdU incorporation. A significant reduction in the fraction of cells in G2/M phase was seen as well. This was associated with increases in the expression of cyclins A and E. Furthermore, LGMN expression was increased in hepatocellular carcinoma cells relative to normal hepatocytes in the same specimens.

CONCLUSIONS:

These findings suggest a new role for LGMN and provide evidence that nuclear Ca(2+) signals regulate cell proliferation in part through the modulation of LGMN expression. Increased expression of LGMN may be involved in liver carcinogenesis.

PMID:
21237226
PMCID:
PMC3158841
DOI:
10.1016/j.jhep.2010.12.022
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center