Dash, S.N., Lehtonen, E., Wasik, A.A., Schepis, A., Paavola, J., Panula, P., Nelson, W.J., and Lehtonen, S. (2014) sept7b is essential for pronephric function and development of left-right asymmetry in zebrafish embryogenesis. Journal of Cell Science. 127(Pt 7):1476-1486.
The conserved septin family of filamentous small GTPases plays important roles in mitosis, cell migration and cell morphogenesis
by forming scaffolds and diffusion barriers. Recent studies in cultured cells in vitro indicate that a septin complex of septin 2, 7 and 9 is required for ciliogenesis and cilia function, but septin function
in ciliogenesis in vertebrate organs in vivo is not understood. We show that sept7b is expressed in ciliated cells in different tissues during early zebrafish development. Knockdown of sept7b by using morpholino antisense oligonucleotides caused misorientation of basal bodies and cilia, reduction of apical actin
and the shortening of motile cilia in Kupffer's vesicle and pronephric tubules. This resulted in pericardial and yolk sac
edema, body axis curvature and hydrocephaly. Notably, in sept7b morphants we detected strong left–right asymmetry defects in the heart and lateral plate mesoderm (situs inversus), reduced fluid flow in the kidney, the formation of kidney cysts and loss of glomerular filtration barrier function. Thus,
sept7b is essential during zebrafish development for pronephric function and ciliogenesis, and loss of expression of sept7b results in defects that resemble human ciliopathies.