PT  - JOURNAL ARTICLE
AU  - Bonaccorsi, Silvia
AU  - Mottier, Violaine
AU  - Giansanti, Maria Grazia
AU  - Bolkan, Bonnie J.
AU  - Williams, Byron
AU  - Goldberg, Michael L.
AU  - Gatti, Maurizio
TI  - The <em>Drosophila</em> Lkb1 kinase is required for spindle formation and
asymmetric neuroblast division
AID  - 10.1242/dev.02848
DP  - 2007 Jun 01
TA  - Development
PG  - 2183--2193
VI  - 134
IP  - 11
4099  - http://dev.biologists.org/content/134/11/2183.short
4100  - http://dev.biologists.org/content/134/11/2183.full
SO  - Development2007 Jun 01; 134
AB  - We have isolated lethal mutations in the Drosophila lkb1 gene (dlkb1), the homolog of C. elegans par-4 and human LKB1 (STK11), which is mutated in Peutz-Jeghers syndrome. We show that these mutations disrupt spindle formation, resulting in frequent polyploid cells in larval brains. In addition, dlkb1 mutations affect asymmetric division of larval neuroblasts (NBs); they suppress unequal cytokinesis, abrogate proper localization of Bazooka, Par-6, DaPKC and Miranda, but affect neither Pins/Gαi localization nor spindle rotation. Most aspects of the dlkb1 phenotype are exacerbated in dlkb1 pins double mutants, which exhibit more severe defects than those observed in either single mutant. This suggests that Dlkb1 and Pins act in partially redundant pathways to control the asymmetry of NB divisions. Our results also indicate that Dlkb1 and Pins function in parallel pathways controlling the stability of spindle microtubules. The finding that Dlkb1 mediates both the geometry of stem cell division and chromosome segregation provides novel insight into the mechanisms underlying tumor formation in Peutz-Jeghers patients.