Akap350 Recruits Eb1 to The Spindle Poles, Ensuring Proper Spindle Orientation and Lumen Formation in 3d Epithelial Cell Cultures

ALMADA, EVANGELINA; TONUCCI, FACUNDO M.; HIDALGO, FLORENCIA; FERRETTI, ANABELA; IBARRA, SOLANGE; PARIANI, ALEJANDRO; VENA, RODRIGO; FAVRE, CRISTIÁN; GIRARDINI, JAVIER; KIERBEL, ARLINET; LAROCCA, M. CECILIA

Scientific Reports

Nature Publishing Group

Año: 2017 vol. 7

The organization of epithelial cells to form hollow organs with a single lumen requires the accuratethree-dimensional arrangement of cell divisions. Mitotic spindle orientation is defned by signalingpathways that provide molecular links between specifc spots at the cell cortex and astral microtubules,which have not been fully elucidated. AKAP350 is a centrosomal/Golgi scafold protein, implicatedin the regulation of microtubule dynamics. Using 3D epithelial cell cultures, we found that cellswith decreased AKAP350 expression (AKAP350KD) formed polarized cysts with abnormal lumenmorphology. Analysis of mitotic cells in AKAP350KD cysts indicated defective spindle alignment. Weestablished that AKAP350 interacts with EB1, a microtubule associated protein that regulates spindleorientation, at the spindle poles. Decrease of AKAP350 expression lead to a signifcant reduction ofEB1 levels at spindle poles and astral microtubules. Conversely, overexpression of EB1 rescued thedefective spindle orientation induced by defcient AKAP350 expression. The specifc delocalization ofthe AKAP350/EB1complex from the centrosome decreased EB1 levels at astral microtubules and leadto the formation of 3D-organotypic structures which resembled AKAP350KD cysts. We conclude thatAKAP350 recruits EB1 to the spindle poles, ensuring EB1 presence at astral microtubules and properspindle orientation during epithelial morphogenesis.