Aragona, P.

Brandi, M.L.

Carbonell Sala, S.

Carossino, A.

Falchetti, A.

Galli, G.

Luzi, E.

Marini, F.

Martineti, V.

Tognarini, I.

Scientific Open-access Literature Archive and Repository

STUDY OF MENIN FUNCTION BY siRNAS INHIBITION OF MEN1-mRNA IN CULTURED CELLSE. Luzi, A. Falchetti, F. Marini, S. Carbonell Sala, I. Tognarini, G. Galli, P. Aragona, V. Martineti, A. Carossino, M.L. BrandiDepartment of Internal Medicine, University of Florence, Florence, ItalyMultiple endocrine neoplasia type 1 (MEN1) is characterized by the occurrence of tumors of the parathy-roids, neuroendocrine cells of the gastro-entero-pancreatic tract, and the anterior pituitary, including morethan 20 other endocrine and nonendocrine tumor combinations. MEN1 gene, a tumor suppressor gene,encodes a protein, menin. Loss of heterozygosity (LOH) at 11q13 has been found in MEN1 tumors, butalso in sporadic pituitary tumors and in 30-70% of sporadic parathyroids and endocrine pancreas tumors,a subset of those with LOH at 11q13 exhibiting mutations in the MEN1 gene. MEN1 mRNA and proteinare expressed in all normal studied tissues, unexplaining the endocrine predominance of neoplasms. Mu-tations in the MEN1 gene frequently predict protein truncation possibly leading to inactivated function con-sistent with the idea of a tumor suppressor gene. Menin interacts with AP-1 transcription factor JunD,Smad3 and inhibits NFkB-mediated transactivation. Moreover, menin also interacts with pem, nm23,GFAP, the 32-kDa subunit of REPA, and nonmuscle myosin II-A heavy chain. Menin uncouples Elk-1,JunD, and c-Jun phosphorylation from MAPK activation. The effects of MEN1 in human neuroendocrinecells and its role in gene regulation remain still elusive. We studied the role of MEN1 mRNA and meninprotein in the global gene expression network in skin fibroblasts from three MEN1 patients with heterozy-gote truncating mutation of gene and from healthy individuals: two sisters with a frame-shift, 738del4 (ex-on 3), introducing a premature stop codon, and a MEN1 individual with a nonsense mutation, R460X (ex-on 10). Densitometric analysis revealed a reduction of MEN1 mRNA expression in fibroblasts from pa-tients vs healthy donor as also confirmed by Real Time RT-PCR. Contrarily, menin protein seems to besimilarly expressed in the three MEN1 patients as also in the healthy control. These preliminary datashow a discrepancy between menin-mRNA and menin protein expression: reduced menin-mRNA expres-sion does not fit with the observed equal expression of menin protein. A mechanism of compensation atmRNA and/or protein levels may explain our results. The down-regulation of the wild-type allele by siRNAand ribozymes in heterozygous MEN1 mutants should give more informations about this hypotheticalmechanism. 216 Clinical Cases in Mineral and Bone Metabolism 2005; 2(3): 185-252BSTR CT (V Congresso CCMBM)  18/11/2005  15.59  Pagina 216FOR REVIEWONLY© CIC EDIZIONI INTERNAZIONALI

Study of menin function by siRNAS inhibition of MEN1-mRNA in cultured cells

http://eprints.bice.rm.cnr.it/8981/1/article.pdf

Study of menin function by siRNAS inhibition of MEN1-mRNA in cultured cells

Abstract

Similar works

Full text

Available Versions

Scientific Open-access Literature Archive and Repository