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Ero1L, a thiol oxidase, is required for Notch signaling through cysteine bridge formation of the Lin12-Notch repeats in Drosophila melanogaster.

Tien AC, Rajan A, Schulze KL, Ryoo HD, Acar M, Steller H, Bellen HJ - J. Cell Biol. (2008)

Bottom Line: Biochemical assays demonstrate that Ero1L is required for formation of disulfide bonds of three Lin12-Notch repeats (LNRs) present in the extracellular domain of Notch.These LNRs are unique to the Notch family of proteins.Therefore, we have uncovered an unexpected requirement for Ero1L in the maturation of the Notch receptor.

View Article: PubMed Central - PubMed

Affiliation: Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA.

ABSTRACT
Notch-mediated cell-cell communication regulates numerous developmental processes and cell fate decisions. Through a mosaic genetic screen in Drosophila melanogaster, we identified a role in Notch signaling for a conserved thiol oxidase, endoplasmic reticulum (ER) oxidoreductin 1-like (Ero1L). Although Ero1L is reported to play a widespread role in protein folding in yeast, in flies Ero1L mutant clones show specific defects in lateral inhibition and inductive signaling, two characteristic processes regulated by Notch signaling. Ero1L mutant cells accumulate high levels of Notch protein in the ER and induce the unfolded protein response, suggesting that Notch is misfolded and fails to be exported from the ER. Biochemical assays demonstrate that Ero1L is required for formation of disulfide bonds of three Lin12-Notch repeats (LNRs) present in the extracellular domain of Notch. These LNRs are unique to the Notch family of proteins. Therefore, we have uncovered an unexpected requirement for Ero1L in the maturation of the Notch receptor.

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Alleles of kiga cause bristle tufting and wing defects. (A) The bristle and socket cells are external structures of a mechanosensory organ (arrowhead). They are present on the head epidermis of a wild-type (WT) fly at stereotypic positions. (B) Homozygous kiga mutant clones show a bristle-tufting phenotype indicating a defect in lateral inhibition. Compared with the regularly spaced bristle patterning on the wild-type head epidermis (A), clear expansion of bristles are observed in kiga clones induced by ey-FLP on the head epidermis (arrowheads). (C) Bristle patterning on the thorax is also affected in homozygous kiga mutant clones. Homozygous mutant kiga clones induced by Ubx-FLP are identified by the trichome marker multiple wing hairs and marked by dashed lines. A higher magnification of a mutant clone in C is shown in C'. (D and E) Wing formation is affected in homozygous kiga mutant clones. Compared with wild-type wing (D), loss of wing tissue around the wing margin (arrow) and wing vein-thickening phenotypes (arrowhead) are associated with homozygous kiga mutant clones (E).
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fig1: Alleles of kiga cause bristle tufting and wing defects. (A) The bristle and socket cells are external structures of a mechanosensory organ (arrowhead). They are present on the head epidermis of a wild-type (WT) fly at stereotypic positions. (B) Homozygous kiga mutant clones show a bristle-tufting phenotype indicating a defect in lateral inhibition. Compared with the regularly spaced bristle patterning on the wild-type head epidermis (A), clear expansion of bristles are observed in kiga clones induced by ey-FLP on the head epidermis (arrowheads). (C) Bristle patterning on the thorax is also affected in homozygous kiga mutant clones. Homozygous mutant kiga clones induced by Ubx-FLP are identified by the trichome marker multiple wing hairs and marked by dashed lines. A higher magnification of a mutant clone in C is shown in C'. (D and E) Wing formation is affected in homozygous kiga mutant clones. Compared with wild-type wing (D), loss of wing tissue around the wing margin (arrow) and wing vein-thickening phenotypes (arrowhead) are associated with homozygous kiga mutant clones (E).

Mentions: To identify novel genes required for ESO development, we performed a mosaic genetic screen on chromosome 3L using the eyeless-flipase (ey-FLP) system (Stowers and Schwarz, 1999; Newsome et al., 2000). We generated ethyl methanesulfonate–induced mutant clones during larval development and screened for bristle defects in adult heads (Fig. 1, A and B). Mutations in a single complementation group (two alleles, 23T and 335QRS) cause a bristle-tufting phenotype in homozygous mutant clones on the head epidermis (Fig. 1 B) and thorax (Fig. 1, C and C'). In addition, mutations in this complementation group cause notching of the wing margin and thickening of the wing veins (Fig. 1, D and E). As these phenotypes are reminiscent of the loss of Notch function, we named this group kiga, which is phonetic for “notched” in Taiwanese.


Ero1L, a thiol oxidase, is required for Notch signaling through cysteine bridge formation of the Lin12-Notch repeats in Drosophila melanogaster.

Tien AC, Rajan A, Schulze KL, Ryoo HD, Acar M, Steller H, Bellen HJ - J. Cell Biol. (2008)

Alleles of kiga cause bristle tufting and wing defects. (A) The bristle and socket cells are external structures of a mechanosensory organ (arrowhead). They are present on the head epidermis of a wild-type (WT) fly at stereotypic positions. (B) Homozygous kiga mutant clones show a bristle-tufting phenotype indicating a defect in lateral inhibition. Compared with the regularly spaced bristle patterning on the wild-type head epidermis (A), clear expansion of bristles are observed in kiga clones induced by ey-FLP on the head epidermis (arrowheads). (C) Bristle patterning on the thorax is also affected in homozygous kiga mutant clones. Homozygous mutant kiga clones induced by Ubx-FLP are identified by the trichome marker multiple wing hairs and marked by dashed lines. A higher magnification of a mutant clone in C is shown in C'. (D and E) Wing formation is affected in homozygous kiga mutant clones. Compared with wild-type wing (D), loss of wing tissue around the wing margin (arrow) and wing vein-thickening phenotypes (arrowhead) are associated with homozygous kiga mutant clones (E).
© Copyright Policy
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2542473&req=5

fig1: Alleles of kiga cause bristle tufting and wing defects. (A) The bristle and socket cells are external structures of a mechanosensory organ (arrowhead). They are present on the head epidermis of a wild-type (WT) fly at stereotypic positions. (B) Homozygous kiga mutant clones show a bristle-tufting phenotype indicating a defect in lateral inhibition. Compared with the regularly spaced bristle patterning on the wild-type head epidermis (A), clear expansion of bristles are observed in kiga clones induced by ey-FLP on the head epidermis (arrowheads). (C) Bristle patterning on the thorax is also affected in homozygous kiga mutant clones. Homozygous mutant kiga clones induced by Ubx-FLP are identified by the trichome marker multiple wing hairs and marked by dashed lines. A higher magnification of a mutant clone in C is shown in C'. (D and E) Wing formation is affected in homozygous kiga mutant clones. Compared with wild-type wing (D), loss of wing tissue around the wing margin (arrow) and wing vein-thickening phenotypes (arrowhead) are associated with homozygous kiga mutant clones (E).
Mentions: To identify novel genes required for ESO development, we performed a mosaic genetic screen on chromosome 3L using the eyeless-flipase (ey-FLP) system (Stowers and Schwarz, 1999; Newsome et al., 2000). We generated ethyl methanesulfonate–induced mutant clones during larval development and screened for bristle defects in adult heads (Fig. 1, A and B). Mutations in a single complementation group (two alleles, 23T and 335QRS) cause a bristle-tufting phenotype in homozygous mutant clones on the head epidermis (Fig. 1 B) and thorax (Fig. 1, C and C'). In addition, mutations in this complementation group cause notching of the wing margin and thickening of the wing veins (Fig. 1, D and E). As these phenotypes are reminiscent of the loss of Notch function, we named this group kiga, which is phonetic for “notched” in Taiwanese.

Bottom Line: Biochemical assays demonstrate that Ero1L is required for formation of disulfide bonds of three Lin12-Notch repeats (LNRs) present in the extracellular domain of Notch.These LNRs are unique to the Notch family of proteins.Therefore, we have uncovered an unexpected requirement for Ero1L in the maturation of the Notch receptor.

View Article: PubMed Central - PubMed

Affiliation: Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA.

ABSTRACT
Notch-mediated cell-cell communication regulates numerous developmental processes and cell fate decisions. Through a mosaic genetic screen in Drosophila melanogaster, we identified a role in Notch signaling for a conserved thiol oxidase, endoplasmic reticulum (ER) oxidoreductin 1-like (Ero1L). Although Ero1L is reported to play a widespread role in protein folding in yeast, in flies Ero1L mutant clones show specific defects in lateral inhibition and inductive signaling, two characteristic processes regulated by Notch signaling. Ero1L mutant cells accumulate high levels of Notch protein in the ER and induce the unfolded protein response, suggesting that Notch is misfolded and fails to be exported from the ER. Biochemical assays demonstrate that Ero1L is required for formation of disulfide bonds of three Lin12-Notch repeats (LNRs) present in the extracellular domain of Notch. These LNRs are unique to the Notch family of proteins. Therefore, we have uncovered an unexpected requirement for Ero1L in the maturation of the Notch receptor.

Show MeSH