Elucidation of the function of type 1 human methionine aminopeptidase during cell cycle progression

Abstract

Processing of the N-terminal initiator methionine is an essential cellular process conserved from prokaryotes to eukaryotes. The enzymes that remove N-terminal methionine are known as methionine aminopeptidases (MetAPs). Human MetAP2 has been shown to be required for the proliferation of endothelial cells and angiogenesis. The physiological function of MetAP1, however, has remained elusive. In this report we demonstrate that a family of inhibitors with a core structure of pyridine-2-carboxylic acid previously developed for the bacterial and yeast MetAP1 is also specific for human MetAP1 (HsMetAP1), as confirmed by both enzymatic assay and high-resolution x-ray crystallography. Treatment of tumor cell lines with the MetAP1-specific inhibitors led to an accumulation of cells in the G2͞M phase, suggesting that HsMetAP1 may play an important role in G2͞M phase transition. Overexpression of HsMetAP1, but not HsMetAP2, conferred resistance of cells to the inhibitors, and the inhibitors caused retention of N-terminal methionine of a known MetAP substrate, suggesting that HsMetAP1 is the cellular target for the inhibitors. In addition, when HsMetAP1 was knocked down by gene-specific siRNA, cells exhibited slower progression during G2͞M phase, a phenotype similar to cells treated with MetAP1 inhibitors. Importantly, MetAP1 inhibitors were able to induce apoptosis of leukemia cell lines, presumably as a consequence of their interference with the G2͞M phase checkpoint. Together, these results suggest that MetAP1 plays an important role in G2͞M phase of the cell cycle and that it may serve as a promising target for the discovery and development of new anticancer agents.aminopeptidase inhibitors ͉ angiogenesis ͉ apoptosis

Molecular cloning and characterization of a gene encoding methionine aminopeptidase 2 of Schistosoma japonicum

“…MAP2 has become an attractive target for the development of drugs against bacteria and other pathological organisms owing to its critical roles in cell viability and growth (Hu et al 2006). On the basis of our previous studies on the differential expression of genes at the different stages of development of Schistosoma japonicum, a gene encoding methionine aminopeptidase 2 (SjMAP2), which is highly expressed in the schistosomulum of S. japonicum at 7 days, was cloned and characterized in this study.…”

Redox Regulation of Methionine Aminopeptidase 2 Activity

“…1A), whereas MetAP1 is devoid of disulfide bonds (8). The MetAP2 Cys 228 -Cys 448 disulfide bond is at the rim of the active site, and the Cys 228 residue of the bond is only three residues distant from the catalytic His 231 (Fig.…”

“…In yeast, the deletion of either map gene results in reduced growth rate, but the loss of both genes is lethal (7). In mammalian cells, inhibition of MetAP1 activity results in cell cycle arrest at G 2 /M, whereas loss of MetAP2 leads to proliferation arrest at G 1 (8,9). Inhibition of either enzyme can also result in apoptotic cell death (10).…”

METAP2 (methionyl aminopeptidase 2)

“…The intracellular enzyme MetAP2 became such a candidate target enzyme due to its inactivation by the widely investigated anticancer agent TNP470 (Abe et al, 1994;Adams et al, 2004;Griffith et al, 1997;Hu et et al, 2006;Hu et al, 2007;Sin et al, 1997). Previously, inhibition of MetAP2 by TNP470 has been shown to activate p53 for cell-cycle arrest.…”