Hedgehog and Decapentaplegic
instruct polarized growth of cell extensions in the Drosophila
trachea
Kato K, Chihara T and Hayashi S
Development 131(21):5253-61 (2004)
SUMMARY
The migration of cellular extensions is guided by signals from tissues
with which they contact. Many axon guidance molecules regulate growth
cone migration by directly regulating actin cytoskeletal dynamics. Secreted
morphogens control global patterns of cell fate decisions during organogenesis
through transcriptional regulation, and constitute another class of guidance
molecules. We have investigated the guidance roles of the morphogens Hedgehog
and Decapentaplegic during directed outgrowth of cytoplasmic extensions
in the Drosophila trachea. A subset of tracheal terminal cells adheres
to the internal surface of the epidermis and elongates cytoplasmic processes
called terminal branches. Hedgehog promotes terminal branch spreading
and its extension over the posterior compartment of the epidermis. Decapentaplegic,
which is expressed at the onset of terminal branching, restricts dorsal
extension of the terminal branch and ensures its monopolar growth. Orthogonal
expression of Hedgehog and Decapentaplegic in the epidermis instructs
monopolar extension of the terminal branch along the posterior compartment,
thereby matching the pattern of airway growth with that of the epidermis.
LINK
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