Elf5 is an epithelium-specific, fibroblast growth factor–sensitive transcription factor in the embryonic lung

Abstract Adult progenitor cells activation is a key event in the formation of adult organs. In Drosophila, formation of abdominal adult trachea depends on the specific activation of tracheal adult progenitors (tracheoblasts) at the Tr4 and Tr5 spiracular branches. Proliferation of these tracheoblasts generates a pool of tracheal cells that migrate toward the posterior part of the trachea by the activation of the branchless/fibroblast growth factor (Bnl/FGF) signaling to form the abdominal adult trachea. Here, we show that, in addition to migration, Bnl/FGF signaling, mediated by the transcription factor Pointed, is also required for tracheoblast proliferation. This tracheoblast activation relies on the expression of the FGF ligand bnl in their nearby branches. Finally, we show that, in the absence of the transcription factor Cut (Ct), Bnl/FGF signaling induces endoreplication of tracheoblasts partially by promoting fizzy-related expression. Altogether, our results suggest a dual role of Bnl/FGF signaling in tracheoblasts, inducing both proliferation and endoreplication, depending on the presence or absence of the transcription factor Ct, respectively.

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Signaling and transcriptional regulation in early mammalian eye development: a link between FGF and MITF

Development ◽

10.1242/dev.127.16.3581 ◽

2000 ◽

Vol 127 (16) ◽

pp. 3581-3591 ◽

Cited By ~ 15

Author(s):

M. Nguyen ◽

H. Arnheiter

Keyword(s):

Gene Expression ◽

Transcription Factor ◽

Transcription Factors ◽

Growth Factor ◽

Fibroblast Growth Factor ◽

Pigment Epithelium ◽

Fibroblast Growth ◽

Optic Vesicle ◽

Surface Ectoderm ◽

Pigmented Epithelium

During vertebrate eye development, the optic vesicle is partitioned into a domain at its distal tip that will give rise to the neuroretina, and another at its proximal base that will give rise to the pigmented epithelium. Both domains are initially bipotential, each capable of giving rise to either neuroretina or pigmented epithelium. The partitioning depends on extrinsic signals, notably fibroblast growth factors, which emanate from the overlying surface ectoderm and induce the adjacent neuroepithelium to assume the neuroretinal fate. Using explant cultures of mouse optic vesicles, we demonstrate that bipotentiality of the optic neuroepithelium is associated with the initial coexpression of the basic-helix-loop-helix-zipper transcription factor MITF, which is later needed solely in the pigmented epithelium, and a set of distinct transcription factors that become restricted to the neuroretina. Implantation of fibroblast growth factor-coated beads close to the base of the optic vesicle leads to a rapid downregulation of MITF and the development of an epithelium that, by morphology, gene expression, and lack of pigmentation, resembles the future neuroretina. Conversely, the removal of the surface ectoderm results in the maintenance of MITF in the distal optic epithelium, lack of expression of the neuroretinal-specific CHX10 transcription factor, and conversion of this epithelium into a pigmented monolayer. This phenomenon can be prevented by the application of fibroblast growth factor alone. In Mitf mutant embryos, parts of the future pigment epithelium become thickened, lose expression of a number of pigment epithelium transcription factors, gain expression of neuroretinal transcription factors, and eventually transdifferentiate into a laminated second retina. The results support the view that the bipotential optic neuroepithelium is characterized by overlapping gene expression patterns and that selective gene repression, brought about by local extrinsic signals, leads to the separation into discrete expression domains and, hence, to domain specification.

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A novel fibroblast growth factor gene expressed in the developing nervous system is a downstream target of the chimeric homeodomain oncoprotein E2A-Pbx1

Development ◽

10.1242/dev.124.17.3221 ◽

1997 ◽

Vol 124 (17) ◽

pp. 3221-3232 ◽

Cited By ~ 10

Author(s):

J.R. McWhirter ◽

M. Goulding ◽

J.A. Weiner ◽

J. Chun ◽

C. Murre

Keyword(s):

Nervous System ◽

Transcription Factor ◽

Growth Factor ◽

Fibroblast Growth Factor ◽

Target Genes ◽

Representational Difference Analysis ◽

Bhlh Transcription Factor ◽

Fibroblast Growth ◽

Downstream Target ◽

Developing Nervous System

Pbx1 is a homeodomain transcription factor that has the ability to form heterodimers with homeodomain proteins encoded by the homeotic selector (Hox) gene complexes and increase their DNA-binding affinity and specificity. A current hypothesis proposes that interactions with Pbx1 are necessary for Hox proteins to regulate downstream target genes that in turn control growth, differentiation and morphogenesis during development. In pre B cell leukemias containing the t(1;19) chromosome translocation, Pbx1 is converted into a strong transactivator by fusion to the activation domain of the bHLH transcription factor E2A. The E2A-Pbx1 fusion protein should therefore activate transcription of genes normally regulated by Pbx1. We have used the subtractive process of representational difference analysis to identify targets of E2A-Pbx1. We show that E2A-Pbx1 can directly activate transcription of a novel member of the fibroblast growth factor family of intercellular signalling molecules, FGF-15. The FGF-15 gene is expressed in a regionally restricted pattern in the developing nervous system, suggesting that FGF-15 may play an important role in regulating cell division and patterning within specific regions of the embryonic brain, spinal cord and sensory organs.

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