Poloz Yekaterina, Catalano Andrew, O'Day Danton H
Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada.
Eukaryot Cell. 2012 Apr;11(4):545-57. doi: 10.1128/EC.05311-11. Epub 2012 Feb 17.
Bestatin methyl ester (BME) is an inhibitor of Zn(2+)-binding aminopeptidases that inhibits cell proliferation and induces apoptosis in normal and cancer cells. We have used Dictyostelium as a model organism to study the effects of BME. Only two Zn(2+)-binding aminopeptidases have been identified in Dictyostelium to date, puromycin-sensitive aminopeptidase A and B (PsaA and PsaB). PSA from other organisms is known to regulate cell division and differentiation. Here we show that PsaA is differentially expressed throughout growth and development of Dictyostelium, and its expression is regulated by developmental morphogens. We present evidence that BME specifically interacts with PsaA and inhibits its aminopeptidase activity. Treatment of cells with BME inhibited the rate of cell growth and the frequency of cell division in growing cells and inhibited spore cell differentiation during late development. Overexpression of PsaA-GFP (where GFP is green fluorescent protein) also inhibited spore cell differentiation but did not affect growth. Using chimeras, we have identified that nuclear versus cytoplasmic localization of PsaA affects the choice between stalk or spore cell differentiation pathway. Cells that overexpressed PsaA-GFP (primarily nuclear) differentiated into stalk cells, while cells that overexpressed PsaAΔNLS2-GFP (cytoplasmic) differentiated into spores. In conclusion, we have identified that BME inhibits cell growth, division, and differentiation in Dictyostelium likely through inhibition of PsaA.
贝司他汀甲酯（BME）是一种锌离子结合氨肽酶抑制剂，可抑制正常细胞和癌细胞的增殖并诱导其凋亡。我们以盘基网柄菌作为模式生物来研究BME的作用。迄今为止，在盘基网柄菌中仅鉴定出两种锌离子结合氨肽酶，即嘌呤霉素敏感氨肽酶A和B（PsaA和PsaB）。已知其他生物中的PSA可调节细胞分裂和分化。在此我们表明，PsaA在盘基网柄菌的整个生长和发育过程中差异表达，其表达受发育形态发生素调控。我们提供的证据表明，BME与PsaA特异性相互作用并抑制其氨肽酶活性。用BME处理细胞可抑制生长细胞的细胞生长速率和细胞分裂频率，并抑制发育后期的孢子细胞分化。PsaA-GFP（其中GFP是绿色荧光蛋白）的过表达也抑制了孢子细胞分化，但不影响生长。通过构建嵌合体，我们确定PsaA的核定位与细胞质定位会影响茎细胞或孢子细胞分化途径的选择。过表达PsaA-GFP（主要定位于细胞核）的细胞分化为茎细胞，而过表达PsaAΔNLS2-GFP（定位于细胞质）的细胞分化为孢子。总之，我们确定BME可能通过抑制PsaA来抑制盘基网柄菌的细胞生长、分裂和分化。
