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A miR-130a-YAP positive feedback loop promotes organ size and tumorigenesis.

Shen S, Guo X, Yan H, Lu Y, Ji X, Li L, Liang T, Zhou D, Feng XH, Zhao JC, Yu J, Gong XG, Zhang L, Zhao B - Cell Res. (2015)

Bottom Line: Organ size determination is one of the most intriguing unsolved mysteries in biology.Here we report that the YAP signaling is sustained through a novel microRNA-dependent positive feedback loop. miR-130a, which is directly induced by YAP, could effectively repress VGLL4, an inhibitor of YAP activity, thereby amplifying the YAP signals.Furthermore, the Drosophila Hippo pathway target bantam functionally mimics miR-130a by repressing the VGLL4 homolog SdBP/Tgi.

View Article: PubMed Central - PubMed

Affiliation: Life Sciences Institute and Innovation Center for Cell Signaling Network Hangzhou, Zhejiang 310058, China.

ABSTRACT
Organ size determination is one of the most intriguing unsolved mysteries in biology. Aberrant activation of the major effector and transcription co-activator YAP in the Hippo pathway causes drastic organ enlargement in development and underlies tumorigenesis in many human cancers. However, how robust YAP activation is achieved during organ size control remains elusive. Here we report that the YAP signaling is sustained through a novel microRNA-dependent positive feedback loop. miR-130a, which is directly induced by YAP, could effectively repress VGLL4, an inhibitor of YAP activity, thereby amplifying the YAP signals. Inhibition of miR-130a reversed liver size enlargement induced by Hippo pathway inactivation and blocked YAP-induced tumorigenesis. Furthermore, the Drosophila Hippo pathway target bantam functionally mimics miR-130a by repressing the VGLL4 homolog SdBP/Tgi. These findings reveal an evolutionarily conserved positive feedback mechanism underlying robustness of the Hippo pathway in size control and tumorigenesis.

No MeSH data available.


Related in: MedlinePlus

bantam represses SdBP/Tgi protein level in Drosophila. (A) Alignment indicates that bantam-seed-matching sequence in SdBP/tgi 3′UTR is conserved in different species of Drosophila. Matching nucleotides were labeled in red. (B)SdBP/tgi 3′UTR sensor is repressed by bantam. Indicated sensors were transfected into Drosophila S2 cells with or without bantam for luciferase assay. Experiments were performed in duplicates. (C)bantam mimic and inhibitor effect on SdBP/Tgi protein level. S2 cells were transfected and analyzed by immunoblotting. (D) Inhibition of bantam increases SdBP/Tgi protein level in vivo. Wing discs expressing UAS-bantam.sp in the P-compartment (indicated by arrowheads) under the control of hhGal4 were subjected to immunostaining for SdBP/Tgi (red). The box in panel (I) is enlarged in panel (III). BS GFP (green) is the bantam sensor. (E) SdBP/Tgi protein level increases in bantam mutant clones in Drosophila wing discs. bantam mutant (BanΔ1) clones were indicated by negative GFP (arrowheads). SdBP/Tgi protein levels were shown by immunostaining (red). Boxes in panels (I-III) were enlarged in (I′-III′). Fly genotype: hsflp;FRT80BubiGFP/FRT80BBanΔ1. (F) microRNA-mediated positive feedback loop of the Hippo pathway. Corresponding components in mammals and Drosophila were shown in the same color.
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fig7: bantam represses SdBP/Tgi protein level in Drosophila. (A) Alignment indicates that bantam-seed-matching sequence in SdBP/tgi 3′UTR is conserved in different species of Drosophila. Matching nucleotides were labeled in red. (B)SdBP/tgi 3′UTR sensor is repressed by bantam. Indicated sensors were transfected into Drosophila S2 cells with or without bantam for luciferase assay. Experiments were performed in duplicates. (C)bantam mimic and inhibitor effect on SdBP/Tgi protein level. S2 cells were transfected and analyzed by immunoblotting. (D) Inhibition of bantam increases SdBP/Tgi protein level in vivo. Wing discs expressing UAS-bantam.sp in the P-compartment (indicated by arrowheads) under the control of hhGal4 were subjected to immunostaining for SdBP/Tgi (red). The box in panel (I) is enlarged in panel (III). BS GFP (green) is the bantam sensor. (E) SdBP/Tgi protein level increases in bantam mutant clones in Drosophila wing discs. bantam mutant (BanΔ1) clones were indicated by negative GFP (arrowheads). SdBP/Tgi protein levels were shown by immunostaining (red). Boxes in panels (I-III) were enlarged in (I′-III′). Fly genotype: hsflp;FRT80BubiGFP/FRT80BBanΔ1. (F) microRNA-mediated positive feedback loop of the Hippo pathway. Corresponding components in mammals and Drosophila were shown in the same color.

Mentions: The Drosophila VGLL4 homolog SdBP/Tgi also competes with Yki for Sd binding, thus regulates organ size34,44. However, miR-130a is not conserved in Drosophila. To explore whether SdBP/Tgi might also be regulated by microRNAs, we used the PicTar microRNA target prediction algorithm. Unexpectedly, bantam is the best-predicted microRNA to target SdBP/Tgi in all six different Drosophila species analyzed, and a conserved bantam-binding site is present in the SdBP/tgi 3′UTR (Figure 7A). To test the functionality of this site, we made an SdBP/tgi 3′UTR sensor, which was inhibited by bantam to an extent similar to that of hid 3′UTR, a known bantam target45 (Figure 7B). However, deletion of the bantam-binding site largely abrogated the repression (Figure 7B). This result strongly suggests that SdBP/Tgi is a target of bantam. Consistently, bantam mimic and bantam inhibitor diminished and elevated the protein levels of endogenous SdBP/Tgi in S2 cells, respectively (Figure 7C). To determine whether endogenous bantam regulates SdBP/Tgi protein level in vivo, we expressed the bantam sponge (UAS-bantam.sp) in Drosophila wing discs under the control of the hh-Gal4 driver, which drives gene expression in the posterior compartments. As shown in Figure 7D, the bantam.sp-expressing compartment exhibited not only elevated bantam sensor GFP signal (panel II) but also increased SdBP/Tgi protein level (panel I, III). Furthermore, in bantam mutant (BanΔ1) clones generated by MARCM in wing discs, the protein level of SdBP/Tgi was increased (Figure 7E). Taken together, bantam, the Drosophila Yki target microRNA, has a function similar to mammalian miR-130a in repressing SdBP/Tgi protein level.


A miR-130a-YAP positive feedback loop promotes organ size and tumorigenesis.

Shen S, Guo X, Yan H, Lu Y, Ji X, Li L, Liang T, Zhou D, Feng XH, Zhao JC, Yu J, Gong XG, Zhang L, Zhao B - Cell Res. (2015)

bantam represses SdBP/Tgi protein level in Drosophila. (A) Alignment indicates that bantam-seed-matching sequence in SdBP/tgi 3′UTR is conserved in different species of Drosophila. Matching nucleotides were labeled in red. (B)SdBP/tgi 3′UTR sensor is repressed by bantam. Indicated sensors were transfected into Drosophila S2 cells with or without bantam for luciferase assay. Experiments were performed in duplicates. (C)bantam mimic and inhibitor effect on SdBP/Tgi protein level. S2 cells were transfected and analyzed by immunoblotting. (D) Inhibition of bantam increases SdBP/Tgi protein level in vivo. Wing discs expressing UAS-bantam.sp in the P-compartment (indicated by arrowheads) under the control of hhGal4 were subjected to immunostaining for SdBP/Tgi (red). The box in panel (I) is enlarged in panel (III). BS GFP (green) is the bantam sensor. (E) SdBP/Tgi protein level increases in bantam mutant clones in Drosophila wing discs. bantam mutant (BanΔ1) clones were indicated by negative GFP (arrowheads). SdBP/Tgi protein levels were shown by immunostaining (red). Boxes in panels (I-III) were enlarged in (I′-III′). Fly genotype: hsflp;FRT80BubiGFP/FRT80BBanΔ1. (F) microRNA-mediated positive feedback loop of the Hippo pathway. Corresponding components in mammals and Drosophila were shown in the same color.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4559818&req=5

fig7: bantam represses SdBP/Tgi protein level in Drosophila. (A) Alignment indicates that bantam-seed-matching sequence in SdBP/tgi 3′UTR is conserved in different species of Drosophila. Matching nucleotides were labeled in red. (B)SdBP/tgi 3′UTR sensor is repressed by bantam. Indicated sensors were transfected into Drosophila S2 cells with or without bantam for luciferase assay. Experiments were performed in duplicates. (C)bantam mimic and inhibitor effect on SdBP/Tgi protein level. S2 cells were transfected and analyzed by immunoblotting. (D) Inhibition of bantam increases SdBP/Tgi protein level in vivo. Wing discs expressing UAS-bantam.sp in the P-compartment (indicated by arrowheads) under the control of hhGal4 were subjected to immunostaining for SdBP/Tgi (red). The box in panel (I) is enlarged in panel (III). BS GFP (green) is the bantam sensor. (E) SdBP/Tgi protein level increases in bantam mutant clones in Drosophila wing discs. bantam mutant (BanΔ1) clones were indicated by negative GFP (arrowheads). SdBP/Tgi protein levels were shown by immunostaining (red). Boxes in panels (I-III) were enlarged in (I′-III′). Fly genotype: hsflp;FRT80BubiGFP/FRT80BBanΔ1. (F) microRNA-mediated positive feedback loop of the Hippo pathway. Corresponding components in mammals and Drosophila were shown in the same color.
Mentions: The Drosophila VGLL4 homolog SdBP/Tgi also competes with Yki for Sd binding, thus regulates organ size34,44. However, miR-130a is not conserved in Drosophila. To explore whether SdBP/Tgi might also be regulated by microRNAs, we used the PicTar microRNA target prediction algorithm. Unexpectedly, bantam is the best-predicted microRNA to target SdBP/Tgi in all six different Drosophila species analyzed, and a conserved bantam-binding site is present in the SdBP/tgi 3′UTR (Figure 7A). To test the functionality of this site, we made an SdBP/tgi 3′UTR sensor, which was inhibited by bantam to an extent similar to that of hid 3′UTR, a known bantam target45 (Figure 7B). However, deletion of the bantam-binding site largely abrogated the repression (Figure 7B). This result strongly suggests that SdBP/Tgi is a target of bantam. Consistently, bantam mimic and bantam inhibitor diminished and elevated the protein levels of endogenous SdBP/Tgi in S2 cells, respectively (Figure 7C). To determine whether endogenous bantam regulates SdBP/Tgi protein level in vivo, we expressed the bantam sponge (UAS-bantam.sp) in Drosophila wing discs under the control of the hh-Gal4 driver, which drives gene expression in the posterior compartments. As shown in Figure 7D, the bantam.sp-expressing compartment exhibited not only elevated bantam sensor GFP signal (panel II) but also increased SdBP/Tgi protein level (panel I, III). Furthermore, in bantam mutant (BanΔ1) clones generated by MARCM in wing discs, the protein level of SdBP/Tgi was increased (Figure 7E). Taken together, bantam, the Drosophila Yki target microRNA, has a function similar to mammalian miR-130a in repressing SdBP/Tgi protein level.

Bottom Line: Organ size determination is one of the most intriguing unsolved mysteries in biology.Here we report that the YAP signaling is sustained through a novel microRNA-dependent positive feedback loop. miR-130a, which is directly induced by YAP, could effectively repress VGLL4, an inhibitor of YAP activity, thereby amplifying the YAP signals.Furthermore, the Drosophila Hippo pathway target bantam functionally mimics miR-130a by repressing the VGLL4 homolog SdBP/Tgi.

View Article: PubMed Central - PubMed

Affiliation: Life Sciences Institute and Innovation Center for Cell Signaling Network Hangzhou, Zhejiang 310058, China.

ABSTRACT
Organ size determination is one of the most intriguing unsolved mysteries in biology. Aberrant activation of the major effector and transcription co-activator YAP in the Hippo pathway causes drastic organ enlargement in development and underlies tumorigenesis in many human cancers. However, how robust YAP activation is achieved during organ size control remains elusive. Here we report that the YAP signaling is sustained through a novel microRNA-dependent positive feedback loop. miR-130a, which is directly induced by YAP, could effectively repress VGLL4, an inhibitor of YAP activity, thereby amplifying the YAP signals. Inhibition of miR-130a reversed liver size enlargement induced by Hippo pathway inactivation and blocked YAP-induced tumorigenesis. Furthermore, the Drosophila Hippo pathway target bantam functionally mimics miR-130a by repressing the VGLL4 homolog SdBP/Tgi. These findings reveal an evolutionarily conserved positive feedback mechanism underlying robustness of the Hippo pathway in size control and tumorigenesis.

No MeSH data available.


Related in: MedlinePlus