X-Message-Number: 11969
Date: Wed, 16 Jun 1999 21:39:11 -0400
From: Jan Coetzee <>
Subject: Directing development

                Directing development
                Cells communicate with each other by releasing proteins
or other chemical
                signals that diffuse to their targets. In the case of
neurons, they send out a long,
                thin process called an axon. Tissues in embryonic fruit
flies seem to use
                filaments to carry signals that tell other tissues how
and when to develop. In
                fruit fly larvae, which are segmented, the filaments
grow from cells at the
                border between the front and rear portion of each
segment. The filaments,
                called cytonemes, are also present in embryonic mice,
which shows that they
                are present in vertebrates and invertebrates.

Cell, Vol. 97, 599-607, May 28, 1999, Copyright   1999 by Cell

Cytonemes: Cellular Processes
that Project to the Principal
Signaling Center in Drosophila Imaginal Discs

Felipe-Andr s Ram rez-Weber1, Thomas B. Kornberg1
1 Department of Biochemistry and Biophysics, University of California,
San Francisco, California 94143

Corresponding author: Thomas B. Kornberg, 415 476 8821 (phone), 415 476
3892 (fax),

Wing imaginal disc cells in Drosophila develop by using information
received from a signaling
center associated with the anterior/posterior compartment border. We
show here that disc cells
have thin, actin-based extensions (cytonemes) that project to this
signaling center. Cytonemes
can be induced when cells from the lateral flanks of a wing disc are
cultured next to cells from
the A/P border or next to a source of fibroblast growth factor. Mouse
limb bud cells also grow
projections during a brief culture period, indicating that cytonemes are
an attribute of both
vertebrate and invertebrate cells. We suggest that cytonemes may be
responsible for some forms
of long-range cell-cell communication.

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