dictyNews Electronic Edition Volume 29, number 1 July 6, 2007 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 ========= The localization of INCENP at the cleavage furrow is dependent on Kif12 and involves interactions of the N-terminus of INCENP with the actin cytoskeleton. Qian Chen1, Gandikota S. Lakshmikanth2, James A. Spudich2, and Arturo De Lozanne1 1Section of Molecular Cell & Developmental Biology and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712. 2Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305 Molecular Biology of the Cell, in press The Inner Centromeric Protein (INCENP) and other chromosomal passenger proteins are known to localize on the cleavage furrow and to play a role in cytokinesis. However, it is not known how INCENP localizes on the furrow or whether this localization is separable from that at the midbody. Here we show that the association of DdINCENP with the cortex of the cleavage furrow involves interactions with the actin cytoskeleton and depends on the presence of the kinesin-6-related protein Kif12. We found that Kif12 is found on the central spindle and the cleavage furrow during cytokinesis. Kif12 is not required for the redistribution of DdINCENP from centromeres to the central spindle. However, in the absence of Kif12, DdINCENP fails to localize on the cleavage furrow. Domain analysis indicates that the Nterminus of DdINCENP is necessary and sufficient for furrow localization and binds directly to the actin cytoskeleton. Our data suggest that INCENP moves from the central spindle to the furrow of a dividing cell by a Kif12 dependent pathway. Once INCENP reaches theequatorial cortex it associates with the actin cytoskeleton where it then concentrates toward the end of cytokinesis. Submitted by: Arturo De Lozanne [a.delozanne@mail.utexas.edu] -------------------------------------------------------------------------------- Prolyl 4-hydroxylase-1 mediates O2-signaling during development of Dictyostelium Christopher M. West, Hanke van der Wel and Zhuo A. Wang Department of Biochemistry & Molecular Biology and the Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104 USA Development, in press Development in multicellular organisms is subject to both environmental and internal signals. In Dictyostelium, starvation induces amoebae to form migratory slugs that translocate from subterranean to exposed sites where they culminate to form sessile fruiting bodies. Culmination, thought to be regulated by anterior tip cells, is selectively suppressed by mild hypoxia by a mechanism that can be partially overridden by another environmental signal, overhead light, or genetic activation of protein kinase A. Dictyostelium expresses, in all cells, an O2-dependent prolyl 4-hydroxylase (P4H1) required for O-glycosylation of Skp1, a subunit of E3SCF-Ub-ligases. P4H1-null cells differentiate the basic prestalk and prespore cell types, but exhibit a selectively increased O2-requirement for culmination from ~12% to near or above ambient (21%) levels. Overexpression of P4H1 reduces the O2 requirement to <5%. The requirement for P4H1 can be met by forced expression of the active enzyme in either prestalk (anterior) or prespore (posterior) cells, or replaced by protein kinase A activation or addition of small numbers of wild-type cells. P4H1-expressing cells accumulate at the anterior end, suggesting that P4H1 enables transcellular signaling by the tip. The evidence provides novel genetic support for the animal-derived O2-sensor model of prolyl 4-hydroxylase function, in an organism that lacks the canonical HIF? transcriptional factor subunit substrate target that is a feature of animal hypoxic signaling. Submitted by: Chris West [Cwest2@ouhsc.edu] ============================================================== [End dictyNews, volume 29, number 1]