Xenopus flotillin1, a novel gene highly expressed in the dorsal nervous system

Abstract

The two paralogues of the Xenopus flotillin1 gene (flotillin1A and flotillin1B), which encodes a putative membraneassociated protein, were cloned from egg, cleavage, and tadpole cDNA libraries. Both mRNAs are present during oogenesis and cleavage stages. After the onset of zygotic transcription, flotillin1 transcripts are first expressed throughout the embryonic ectoderm and become enhanced in the presumptive neural ectoderm as the neural plate forms. As the neural tube forms and differentiates, flotillin1 transcripts become enriched in the dorsal half, with particularly high expression in dorsal primary neurons. At early tail bud stages, there is additional expression in the paraxial mesoderm. At late tail bud stages, flotillin1A is expressed in branchial arch mesenchyme, the overlying branchial ectoderm and in dorsal somitic mesoderm, whereas flotillin1B expression is more restricted in the dorsal neural tube and head sensory structures. This report is the first comprehensive developmental description in any animal of the expression pattern of this gene, whose protein product in several systems plays important roles in signal transduction events. Developmental Dynamics 231:881-887, 2004.

Ancient origin of reggie (flotillin), reggie-like, and other lipid-raft proteins: convergent evolution of the SPFH domain

“…The phylogenetic tree of representative metazoan reggies/flotillins in figure 4A recovers the expected reggie-1 and -2 ancient monophyletic groups with internal branching patterns that correspond well with the known taxonomy [1,37], as well as with the duplication of reggies/flotillins in bony fish [1] and in the amphibian Xenopus laevis [38]. Phylogenetic analysis of each separate domain recovers the same tree (not shown).…”

Scaffolding microdomains and beyond: the function of reggie/flotillin proteins

“…This emphasizes the important role of reggies during early development [E. Riviera-Milla, E. Malaga-Trillo and C. A. O. Stuermer, unpublished observations]. An expression pattern similar to the one observed in zebrafish was reported for reggie-2 in the developing Xenopus [34]. Due to the partial duplication of the Xenopus laevis genome, there are also two copies of the reggie-2 gene in frogs.…”

“…Flotillin-1a (reggie-2a) is expressed in several neural crest derivates, including the olfactory pit and cranial ganglia, and in the dorsal regions of the neural tube, including the primary neurons in the dorsal spinal cord. Flotillin-1b (reggie-2b) expression is restricted to small domains of the dorsal neural tube, and a low level of expression is found in the branchial arches [34]. Unfortunately, the expression pattern of reggie-1 was not investigated in this study.…”

“…Although it was repeatedly claimed that reggies reside within caveolae [5,32], we and others have convincingly shown that reggie clusters are distinct from caveolae. First of all, reggies are expressed and reggie clusters are detected in cell types which do not express any caveolins -most importantly neurons and lymphocytes [4,29]; caveolins and reggies show distinct expression patterns both in adult tissues [33] and in developing organisms [34]. Even in cells that do express both caveolin and reggies, reggie microdomains are clearly distinct and located outside of caveolae [4,29,35].…”

EphrinB2 affects apical constriction in Xenopus embryos and is regulated by ADAM10 and flotillin-1

“…We recently identified the lipid raft protein flotillin-2 as an ephrinB1 interactor by mass spectrometric analysis of immune complexes from Xenopus embryos over-expressing ephrinB1. Based on these results, we tested whether ephrinB2 was able to interact with flotillin-1 and flotillin-2 since the intracellular domains of ephrinB1 and ephrinB2 are 82% identical and flotillin-1 and flotillin-2, like the ephrinBs, are known to be expressed in the neural tissue in vivo 15–17 . Flag-tagged ephrinB2 and HA-tagged flotillin-1a or -1b were overexpressed in Xenopus oocytes, and co-immunoprecipitation analysis was performed.…”