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Jun N-terminal kinase signaling makes a face

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ABSTRACT

decapentaplegic (dpp), the Drosophila ortholog of BMP 2/4, directs ventral adult head morphogenesis through expression in the peripodial epithelium of the eye-antennal disc. This dpp expressing domain exerts effects both on the peripodial epithelium, and the underlying disc proper epithelium. We have uncovered a role for the Jun N-terminal kinase (JNK) pathway in dpp-mediated ventral head development. JNK activity is required for dpp's action on the disc proper, but in the absence of dpp expression, excessive JNK activity is produced, leading to specific loss of maxillary palps. In this review we outline our hypotheses on how dpp acts by both short range and longer range mechanisms to direct head morphogenesis and speculate on the dual role of JNK signaling in this process. Finally, we describe the regulatory control of dpp expression in the eye-antennal disc, and pose the problem of how the various expression domains of a secreted protein can be targeted to their specific functions.

No MeSH data available.


The Drosophila JNK pathway. The core signaling module is comprised of a JNKK: Hemipterous, JNK: Basket, Jun: Jun related antigen, and Fos: Kayak (Kay). Upstream JNKKKs and further upstream inputs diversify, and lend specificity to the signaling pathway. Other pathway members include: Wengen (Wgn), Grindelwald (Grnd), PDGF- and VEGF-related factor (PVF), PDGF- and VEGF-receptor related (PVR), Wingless (Wg), Frizzled (Fz), TNF-receptor-associated factor 4 (Traf4), TNF-receptor-associated factor 6 (Traf6), Misshapen (Msn), Dishevelled (Dsh), TGF-β activated kinase 1 (Tak1), and Apoptotic signal-regulating kinase 1 (Ask1).
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f0002: The Drosophila JNK pathway. The core signaling module is comprised of a JNKK: Hemipterous, JNK: Basket, Jun: Jun related antigen, and Fos: Kayak (Kay). Upstream JNKKKs and further upstream inputs diversify, and lend specificity to the signaling pathway. Other pathway members include: Wengen (Wgn), Grindelwald (Grnd), PDGF- and VEGF-related factor (PVF), PDGF- and VEGF-receptor related (PVR), Wingless (Wg), Frizzled (Fz), TNF-receptor-associated factor 4 (Traf4), TNF-receptor-associated factor 6 (Traf6), Misshapen (Msn), Dishevelled (Dsh), TGF-β activated kinase 1 (Tak1), and Apoptotic signal-regulating kinase 1 (Ask1).

Mentions: To tease apart these functions, we must determine what parts of the JNK pathway are used in common between them. The basic JNK signaling module, consisting of Hep, Bsk, Kay, and Jra, can be activated by many upstream modifiers (Fig. 2). These inputs from different modifiers impart specificity to the basic signaling module. In addition, JNK signal transduction can target multiple downstream effectors. All this explains the wide variety of cellular activities controlled by JNK signaling. Our observation that targeted peripodial gene expression can produce flies with only ventral cuticle and vibrissae defects, versus flies that are missing only maxillary palps, suggests that we may be able to discriminate among these varied JNK functions with a genetic screen of available RNAi and protein reagents.Figure 2.


Jun N-terminal kinase signaling makes a face
The Drosophila JNK pathway. The core signaling module is comprised of a JNKK: Hemipterous, JNK: Basket, Jun: Jun related antigen, and Fos: Kayak (Kay). Upstream JNKKKs and further upstream inputs diversify, and lend specificity to the signaling pathway. Other pathway members include: Wengen (Wgn), Grindelwald (Grnd), PDGF- and VEGF-related factor (PVF), PDGF- and VEGF-receptor related (PVR), Wingless (Wg), Frizzled (Fz), TNF-receptor-associated factor 4 (Traf4), TNF-receptor-associated factor 6 (Traf6), Misshapen (Msn), Dishevelled (Dsh), TGF-β activated kinase 1 (Tak1), and Apoptotic signal-regulating kinase 1 (Ask1).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036929&req=5

f0002: The Drosophila JNK pathway. The core signaling module is comprised of a JNKK: Hemipterous, JNK: Basket, Jun: Jun related antigen, and Fos: Kayak (Kay). Upstream JNKKKs and further upstream inputs diversify, and lend specificity to the signaling pathway. Other pathway members include: Wengen (Wgn), Grindelwald (Grnd), PDGF- and VEGF-related factor (PVF), PDGF- and VEGF-receptor related (PVR), Wingless (Wg), Frizzled (Fz), TNF-receptor-associated factor 4 (Traf4), TNF-receptor-associated factor 6 (Traf6), Misshapen (Msn), Dishevelled (Dsh), TGF-β activated kinase 1 (Tak1), and Apoptotic signal-regulating kinase 1 (Ask1).
Mentions: To tease apart these functions, we must determine what parts of the JNK pathway are used in common between them. The basic JNK signaling module, consisting of Hep, Bsk, Kay, and Jra, can be activated by many upstream modifiers (Fig. 2). These inputs from different modifiers impart specificity to the basic signaling module. In addition, JNK signal transduction can target multiple downstream effectors. All this explains the wide variety of cellular activities controlled by JNK signaling. Our observation that targeted peripodial gene expression can produce flies with only ventral cuticle and vibrissae defects, versus flies that are missing only maxillary palps, suggests that we may be able to discriminate among these varied JNK functions with a genetic screen of available RNAi and protein reagents.Figure 2.

View Article: PubMed Central - PubMed

ABSTRACT

decapentaplegic (dpp), the Drosophila ortholog of BMP 2/4, directs ventral adult head morphogenesis through expression in the peripodial epithelium of the eye-antennal disc. This dpp expressing domain exerts effects both on the peripodial epithelium, and the underlying disc proper epithelium. We have uncovered a role for the Jun N-terminal kinase (JNK) pathway in dpp-mediated ventral head development. JNK activity is required for dpp's action on the disc proper, but in the absence of dpp expression, excessive JNK activity is produced, leading to specific loss of maxillary palps. In this review we outline our hypotheses on how dpp acts by both short range and longer range mechanisms to direct head morphogenesis and speculate on the dual role of JNK signaling in this process. Finally, we describe the regulatory control of dpp expression in the eye-antennal disc, and pose the problem of how the various expression domains of a secreted protein can be targeted to their specific functions.

No MeSH data available.