Development, Vol 125, Issue 14 2565-2576, Copyright © 1998 by Company of Biologists

JOURNAL ARTICLES

Identification and analysis of a gene that is essential for morphogenesis and prespore cell differentiation in Dictyostelium

H Yasukawa, S Mohanty and RA Firtel
Department of Biology, Center for Molecular Genetics, University of California, San Diego, La Jolla CA 92093-0634, USA.

We have identified a gene (PslA) that is expressed throughout Dictyostelium development and encodes a novel protein that is required for proper aggregation and subsequent cell-type differentiation and morphogenesis. pslA null (pslA-) cells produce large aggregation streams under conditions in which wild-type cells form discrete aggregates. Tips form along the stream, elongate to produce a finger, and eventually form a terminal structure that lacks a true sorus (spore head). More than half of the cells remain as a mass at the base of the developing fingers. The primary defect in the pslA- strain is the inability to induce prespore cell differentiation. Analyses of gene expression show a complete lack of prespore-specific gene expression and no mature spores are produced. In chimeras with wild-type cells, pslA- cells form the prestalk domain and normal, properly proportioned fruiting bodies can be produced. This indicates that pslA- cells are able to interact with wild-type cells and regulate patterning, even though pslA- cells are unable to express prespore cell-type-specific genes, do not participate in prespore cell differentiation and do not produce pslA- spores in the chimeras. While pslA- cells produce mature, vacuolated stalk cells during multicellular development, pslA- cells are unable to do so in vitro in response to exogenous DIF (a morphogen required for prestalk and stalk cell differentiation). These results indicate that pslA- cells exhibit a defect in the prestalk/stalk cell pathways under these experimental conditions. Our results suggest that PslA's primary function is to regulate prespore cell determination very early in the prespore pathway via a cell-autonomous mechanism, possibly at the time of the initial prestalk/prespore cell-fate decision. Indirect immunofluorescence of myc-tagged PslA localizes the protein to the nucleus, suggesting that PslA may function to control the prespore pathway at the level of transcription.
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				S Mohanty, K. Jermyn, A Early, T Kawata, L Aubry, A Ceccarelli, P Schaap, J. Williams, and R. Firtel Evidence that the Dictyostelium Dd-STATa protein is a repressor that regulates commitment to stalk cell differentiation and is also required for efficient chemotaxis Development, January 8, 1999; 126(15): 3391 - 3405. [Abstract] [PDF]