Caenorhabditis elegans expresses three functional profilins in a tissue-specific manner.
Profilins are actin binding proteins, which also interact with polyphosphoinositides and proline-rich ligands. On the basis of the genome sequence, three diverse profilin homologues (PFN) are predicted to exist in Caenorhabditis elegans. We show that all three isoforms PFN-1, PFN-2, and PFN-3 are expressed in vivo and biochemical studies indicate they bind actin and influence actin dynamics in a similar manner. In addition, they bind poly(L-proline) and phosphatidylinositol 4,5-bisphosphate micelles. PFN-1 is essential whereas PFN-2 and PFN-3 are nonessential. Immunostainings revealed different expression patterns for the profilin isoforms. In embryos, PFN-1 localizes in the cytoplasm and to the cell-cell contacts at the early stages, and in the nerve ring during later stages. During late embryogenesis, expression of PFN-3 was specifically detected in body wall muscle cells. In adult worms, PFN-1 is expressed in the neurons, the vulva, and the somatic gonad, PFN-2 in the intestinal wall, the spermatheca, and the pharynx, and PFN-3 localizes in a striking dot-like fashion in body wall muscle. Thus the model organism Caenorhabditis elegans expresses three profilin isoforms and is the first invertebrate animal with tissue-specific profilin expression.
Polet
D
D
Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
Lambrechts
A
A
Ono
K
K
Mah
A
A
Peelman
F
F
Vandekerckhove
J
J
Baillie
D L
DL
Ampe
C
C
Ono
S
S
D008841:Actin Cytoskeleton / Q000187:drug effects; D000199:Actins / Q000737:chemistry; D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology / Q000378:metabolism*; D002465:Cell Movement; D002470:Cell Survival; D004625:Embryo, Nonmammalian / Q000378:metabolism; D066298:In Vitro Techniques; D008954:Models, Biological; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010455:Peptides / Q000737:chemistry; D051304:Profilins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology; D011392:Proline / Q000737:chemistry; D011485:Protein Binding; D020033:Protein Isoforms / Q000378:metabolism; D011817:Rabbits
D000199:Actins; D010455:Peptides; D051304:Profilins; D020033:Protein Isoforms; D011392:Proline