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SNX17 regulates Notch pathway and pancreas development through the retromer-dependent recycling of Jag1.

Yin W, Liu D, Liu N, Xu L, Li S, Lin S, Shu X, Pei D - Cell Regen (Lond) (2012)

Bottom Line: SNX17 is a sorting nexin family protein implicated in vesicular trafficking and we find it is specifically required in the ligand-expressing cells for Notch signaling.Mechanistically, SNX17 regulates the protein level of Jag1a on plasma membrane by binding to Jag1a and facilitating the retromer-dependent recycling of the ligand.In zebrafish, inhibition of this SNX17-mediated Notch signaling pathway results in defects in neurogenesis as well as pancreas development.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530 China.

ABSTRACT

Background: Notch is one of the most important signaling pathways involved in cell fate determination. Activation of the Notch pathway requires the binding of a membrane-bound ligand to the Notch receptor in the adjacent cell which induces proteolytic cleavages and the activation of the receptor. A unique feature of the Notch signaling is that processes such as modification, endocytosis or recycling of the ligand have been reported to play critical roles during Notch signaling, however, the underlying molecular mechanism appears context-dependent and often controversial.

Results: Here we identified SNX17 as a novel regulator of the Notch pathway. SNX17 is a sorting nexin family protein implicated in vesicular trafficking and we find it is specifically required in the ligand-expressing cells for Notch signaling. Mechanistically, SNX17 regulates the protein level of Jag1a on plasma membrane by binding to Jag1a and facilitating the retromer-dependent recycling of the ligand. In zebrafish, inhibition of this SNX17-mediated Notch signaling pathway results in defects in neurogenesis as well as pancreas development.

Conclusions: Our results reveal that SNX17, by acting as a cargo-specific adaptor, promotes the retromer dependent recycling of Jag1a and Notch signaling and this pathway is involved in cell fate determination during zebrafish neurogenesis and pancreas development.

No MeSH data available.


SNX17 co-immunoprecipitates with Jag1a. (A) The Flag-tagged SNX17 pulled down the HA-tagged Jag1a when co-expressed in 293 T cells. SNX11 is a PX-only SNX family member and was used as the negative control. (B) HA-Jag1a co-immunoprecipitated with full-length or the FERM-like domain of SNX17. The PX domain failed to be pulled-down in the same assay. (C) SNX17 co-localized with Jag1a in 293 T cells.
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Fig3: SNX17 co-immunoprecipitates with Jag1a. (A) The Flag-tagged SNX17 pulled down the HA-tagged Jag1a when co-expressed in 293 T cells. SNX11 is a PX-only SNX family member and was used as the negative control. (B) HA-Jag1a co-immunoprecipitated with full-length or the FERM-like domain of SNX17. The PX domain failed to be pulled-down in the same assay. (C) SNX17 co-localized with Jag1a in 293 T cells.

Mentions: SNX family proteins can function as cargo-specific adaptors for vesicular trafficking. Our finding that SNX17 regulated Notch signaling in the ligand-expressing cells raised the possibility that it functioned as an adaptor for the trafficking of the ligand. We determined whether SNX17can interact with Jag1, a ligand most effective in stimulating Notch activity in 293 T cells (Figure 2B). We found that Flag-tagged SNX17 pulled down HA-tagged Jag1a and vice versa (Figure 3A, B). As a control, SNX11, which is a PX-only SNX family member, did not pull-down Jag1a under the same condition. This observation suggested that the interaction between SNX17 and Jag1a is specific. Structurally, SNX17 contains a FERM-like domain which is not present in SNX11 or most of the other SNX family proteins [31]. We investigated whether this FERM-like domain was essential for interaction with Jag1a. As shown in Figure 3B, Jag1a co-immunoprecipitated with the FERM-like, but not the PX domain of SNX17. Thus, the FERM-like domain of NX17 mediated the interaction between SNX17 and Jag1a. We then investigated the subcellular distribution of SNX17 and Jag1a in the same cell line and found that SNX17 accumulated at Jag1a-positive vesicles (Figure 3C). These data further suggest that SNX17 might regulate the intracellular trafficking of Jag1a.Figure 3


SNX17 regulates Notch pathway and pancreas development through the retromer-dependent recycling of Jag1.

Yin W, Liu D, Liu N, Xu L, Li S, Lin S, Shu X, Pei D - Cell Regen (Lond) (2012)

SNX17 co-immunoprecipitates with Jag1a. (A) The Flag-tagged SNX17 pulled down the HA-tagged Jag1a when co-expressed in 293 T cells. SNX11 is a PX-only SNX family member and was used as the negative control. (B) HA-Jag1a co-immunoprecipitated with full-length or the FERM-like domain of SNX17. The PX domain failed to be pulled-down in the same assay. (C) SNX17 co-localized with Jag1a in 293 T cells.
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Related In: Results  -  Collection

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Fig3: SNX17 co-immunoprecipitates with Jag1a. (A) The Flag-tagged SNX17 pulled down the HA-tagged Jag1a when co-expressed in 293 T cells. SNX11 is a PX-only SNX family member and was used as the negative control. (B) HA-Jag1a co-immunoprecipitated with full-length or the FERM-like domain of SNX17. The PX domain failed to be pulled-down in the same assay. (C) SNX17 co-localized with Jag1a in 293 T cells.
Mentions: SNX family proteins can function as cargo-specific adaptors for vesicular trafficking. Our finding that SNX17 regulated Notch signaling in the ligand-expressing cells raised the possibility that it functioned as an adaptor for the trafficking of the ligand. We determined whether SNX17can interact with Jag1, a ligand most effective in stimulating Notch activity in 293 T cells (Figure 2B). We found that Flag-tagged SNX17 pulled down HA-tagged Jag1a and vice versa (Figure 3A, B). As a control, SNX11, which is a PX-only SNX family member, did not pull-down Jag1a under the same condition. This observation suggested that the interaction between SNX17 and Jag1a is specific. Structurally, SNX17 contains a FERM-like domain which is not present in SNX11 or most of the other SNX family proteins [31]. We investigated whether this FERM-like domain was essential for interaction with Jag1a. As shown in Figure 3B, Jag1a co-immunoprecipitated with the FERM-like, but not the PX domain of SNX17. Thus, the FERM-like domain of NX17 mediated the interaction between SNX17 and Jag1a. We then investigated the subcellular distribution of SNX17 and Jag1a in the same cell line and found that SNX17 accumulated at Jag1a-positive vesicles (Figure 3C). These data further suggest that SNX17 might regulate the intracellular trafficking of Jag1a.Figure 3

Bottom Line: SNX17 is a sorting nexin family protein implicated in vesicular trafficking and we find it is specifically required in the ligand-expressing cells for Notch signaling.Mechanistically, SNX17 regulates the protein level of Jag1a on plasma membrane by binding to Jag1a and facilitating the retromer-dependent recycling of the ligand.In zebrafish, inhibition of this SNX17-mediated Notch signaling pathway results in defects in neurogenesis as well as pancreas development.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530 China.

ABSTRACT

Background: Notch is one of the most important signaling pathways involved in cell fate determination. Activation of the Notch pathway requires the binding of a membrane-bound ligand to the Notch receptor in the adjacent cell which induces proteolytic cleavages and the activation of the receptor. A unique feature of the Notch signaling is that processes such as modification, endocytosis or recycling of the ligand have been reported to play critical roles during Notch signaling, however, the underlying molecular mechanism appears context-dependent and often controversial.

Results: Here we identified SNX17 as a novel regulator of the Notch pathway. SNX17 is a sorting nexin family protein implicated in vesicular trafficking and we find it is specifically required in the ligand-expressing cells for Notch signaling. Mechanistically, SNX17 regulates the protein level of Jag1a on plasma membrane by binding to Jag1a and facilitating the retromer-dependent recycling of the ligand. In zebrafish, inhibition of this SNX17-mediated Notch signaling pathway results in defects in neurogenesis as well as pancreas development.

Conclusions: Our results reveal that SNX17, by acting as a cargo-specific adaptor, promotes the retromer dependent recycling of Jag1a and Notch signaling and this pathway is involved in cell fate determination during zebrafish neurogenesis and pancreas development.

No MeSH data available.