dictyNews Electronic Edition Volume 27, number 7 September 1, 2006 Please submit abstracts of your papers as soon as they have been accepted for publication by sending them to dicty@northwestern.edu or by using the form at http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit. Back issues of dictyNews, the Dicty Reference database and other useful information is available at dictyBase - http://dictybase.org. ============= Abstracts ============= Anti-leukemic activities of Dictyostelium secondary metabolites: A novel aromatic metabolite, 4-methyl-5-n-propylbenzene-1,3-diol, isolated from Dictyostelium mucoroides suppresses cell growth in human leukemia K562 and HL-60 cells. Haruhisa Kikuchi, Yoshiteru Oshima, Aya Ichimura, Naomi Gokan, Aiko Hasegawa, Kohei Hosaka, & Yuzuru Kubohara Life Sciences, in press It has previously been shown that DIF-1, a differentiation-inducing factor of the cellular slime mold Dictyostelium discoideum, possesses antitumor activities in mammalian tumor cells and that neuronal differentiation of PC12 cells can be induced with furanodictines (FDs), aminosugar analogs found in D. discoideum, or dictyoglucosamines (DGs), N-acetyl glucosamine derivatives (DG-A from D. purpureum and DG-B from D. discoideum). Thus, cellular slime molds are attractive natural resources that may provide valuable lead compounds to be utilized in the field of pharmacology and medicine. In this study, we have isolated a novel aromatic compound, 4-methyl-5-n-propylbenzene-1,3-diol (MPBD), from fruiting bodies of the cellular slime mold D. mucoroides and assessed the in vitro antiproliferative activities of MPBD, FDs, and DGs in human leukemia K562 and HL-60 cells. MPBD at 20-80 micro M dose-dependently suppressed cell growth in both K562 and HL-60 cells. While FDs at 10-80 micro M did not affect cell growth, DGs at 10-40 micro M dose-dependently suppressed cell growth in the cells. Although we failed to find the roles of FDs and DGs in the original organisms, MPBD at 5-20 micro M was found to promote stalk cell formation in D. discoideum. The present results indicate that MPBD, DGs or their derivatives may have therapeutic potential in the treatment of cancer and confirm our expectations regarding cellular slime molds as drug resources. Submitted by: Yuzuru Kubohara [kubohara@showa.gunma-u.ac.jp] ----------------------------------------------------------------------------- Mechanically-induced actin-mediated rocketing of phagosomes Margaret Clarke1, Annette MŸller-Taubenberger2, 5, Kurt I. Anderson3, Ulrike Engel4, and GŸnther Gerisch2 1Program in Molecular, Cell, and Developmental Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73121 2Max-Planck-Institut fŸr Biochemie, 82152 Martinsried, Germany 3Max-Planck-Institut of Molecular Cell Biology and Genetics, 01037 Dresden, Germany 4University of Heidelberg, Nikon Imaging Center, 69120 Heidelberg, Germany 5Present address: Ludwig Maximilians University Munich, Institute for Cell Biology (ABI), 80336 MŸnchen, Germany 1Corresponding author. E-mail: clarkem@omrf.ouhsc.edu Molecular Biology of the Cell, in press. Actin polymerization can be induced in Dictyostelium by compressing the cells to bring phagosomes filled with large particles into contact with the plasma membrane. Asymmetric actin assembly results in rocketing movement of the phagosomes. We show that the compression-induced assembly of actin at the cytoplasmic face of the plasma membrane involves the Arp2/3 complex. We also identify two other proteins associated with the mechanically-induced actin assembly. The class I myosin MyoB accumulates at the plasma membrane-phagosome interface early during the initiation of the response, and coronin is recruited as the actin filaments are disassembling. The forces generated by rocketing phagosomes are sufficient to push the entire microtubule apparatus forward and to dislocate the nucleus. Submitted by: Margaret Clarke [Margaret-Clarke@omrf.ouhsc.edu] ============================================================================== [End dictyNews, volume 27, number 7]