ELMOD3-Rab1A-Flotillin2 cascade regulates lumen formation via vesicle trafficking in Ciona notochord

Abstract

Lumen development is a crucial phase in tubulogenesis, although its molecular mechanisms are largely unknown. In this study, we discovered an ELMO domain-containing 3 (ELMOD3), which belongs to ADP-ribosylation factor GTPase-activating protein family, was necessary to form the notochord lumen in Ciona larvae . We demonstrated that ELMOD3 interacted with lipid raft protein Flotillin2 and regulated its subcellular localization. The loss-of-function of Flotillin2 prevented notochord lumen formation. Furthermore, we found that ELMOD3 also interacted with Rab1A, which is the regulatory GTPase for vesicle trafficking and located at the notochord cell surface. Rab1A mutations arrested the lumen formation, phenocopying the loss-of-function of ELMOD3 and Flotillin2. Our findings further suggested that Rab1A interactions influenced Flotillin2 localization. We thus identified a unique pathway in which ELMOD3 interacted with Rab1A, which controlled the Flotillin2-mediated vesicle trafficking from cytoplasm to apical membrane, required for Ciona notochord lumen formation.

Dynamics of Chromatin Opening across Larval Development in the Urochordate Ascidian Ciona savignyi

“…They might be involved in epidermal cell extension and notochordal lumen formation and expansion. The RNA-seq results identified DEGs enriched in membrane transport and ion transportrelated pathways, consistent with the formation of the notochordal lumen through the establishment of polarity, cytoskeletal rearrangement, and expansion of the notochordal lumen with ion flow (SLC26A), proteoglycan secretion, vesicle trafficking (ELMOD3), and replenishment of the apical membrane (14-3-3εa and caveolin) [17,[59][60][61][62].…”

“…Its early embryonic processes are relatively simple, its transgenic technology has been developed [ 9 ], and its genome has been sequenced [ 10 , 11 ] and deposited in the EDomics database [ 12 ]. Distinct morphological changes occur in various tissues of the ascidian from the early to the late tailbud stages, including tail bending [ 13 ] and epidermal and muscle cell extension, and notochord cells also undergo a series of complex morphological events, including elongation [ 14 ], migration, lumen formation [ 15 , 16 , 17 , 18 ], and lumen fusion [ 14 , 19 , 20 ]. The cytological process of ascidian tailbud development has been extensively studied, but the molecular mechanism of its regulation is poorly understood.…”

Gene regulation analysis of patient-derived iPSCs and its CRISPR-corrected control provides a new tool for studying perturbations of ELMOD3 c.512A>G mutation during the development of inherited hearing loss

“…Deletion of Elmod1 in vitro results in the decreased ability of cells to form primary cilia, and the loss of a subset of proteins from cilia [ 8 ]. ELMOD3 interacts with Rab1A and Flotillin2 to regulate lumen formation via vesicle trafficking [ 30 ]. The current work found a series of DEGs related to sensory epithelial development and cytoskeleton organization through functional enrichment and PPI network analysis, including ATOH1 , VIM , PRPH and NEFL, which may be involved in the pathogenesis of ELMOD3 causing deafness.…”