Expression of mutant CHMP2B, an ESCRT-III component involved in frontotemporal dementia, causes eye deformities due to Notch misregulation in Drosophila.

Abstract

Endosomal sorting complexes required for transport (ESCRTs) mediate sorting of ubiquitinated membrane proteins into multivesicular bodies en route to lysosomes for degradation. A mutation in CHMP2B (CHMP2B(Intron5), an ESCRT-III component) that is associated with a hereditary form of frontotemporal dementia (FTD3) disrupts the endosomal-lysosomal pathway and causes accumulation of autophagosomes and multilamellar structures. We previously demonstrated that expression of CHMP2B(Intron5) in the Drosophila eye using GMR-Gal4 causes misregulation of the Toll receptor pathway. Here, we show that ectopic expression of CHMP2B(Intron5) using eyeless-Gal4 (ey>CHMP2B(Intron5)), a driver with different spatiotemporal expression attributes than GMR-Gal4 in the Drosophila eye, causes eye deformities when compared to expression of wild-type CHMP2B (CHMP2B(WT)) and the Drosophila homologue of CHMP2B (CG4618). In addition, ey>CHMP2B(Intron5) flies showed defects in photoreceptor cell patterning and phototactic behavior. Furthermore, ey>CHMP2B(Intron5) flies showed accumulation of Notch in enlarged endosomes and up-regulation of Notch activity. Partial loss of Notch activity in ey>CHMP2B(Intron5) flies significantly rescued eye deformities, photoreceptor patterning defect, and phototactic behavior defect, indicating that these defects are primarily due to Notch misregulation. These results demonstrate that CHMP2B(Intron5) preferentially affects different receptor signaling pathways in a cellular and developmental context-dependent manner.

• Authors: Abigael Cheruiyot, Jin-A Lee, Fen-Biao Gao, S Tariq Ahmad
• Journal: FASEB journal : official publication of the Federation of American Societies for Experimental Biology (FASEB J) Vol. 28 Issue 2 Pg. 667-75 (Feb 2014) ISSN: 1530-6860 [Electronic] United States
• PMID: 24158394 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• CHMP2B protein, Drosophila
• Drosophila Proteins
• Endosomal Sorting Complexes Required for Transport
• N protein, Drosophila
• Receptors, Notch
• Vesicular Transport Proteins

Topics

• Animals
• Blotting, Western
• Drosophila
• Drosophila Proteins (genetics, metabolism)
• Endosomal Sorting Complexes Required for Transport (genetics, metabolism)
• Eye (metabolism, pathology)
• Frontotemporal Dementia (genetics, metabolism)
• Polymerase Chain Reaction
• Receptors, Notch (genetics, metabolism)
• Vesicular Transport Proteins (genetics, metabolism)