We previously showed that excess centrosomes interfere with repolarization along the forward–rearward axis in sprouting EC [
17], and thus we hypothesized that supernumerary centrosomes disrupt multiple EC polarity axes. We examined the polarity between EC sharing junctions using an inducible system to overexpress polo-like kinase 4 (Plk4) in human umbilical vein endothelial cells (HUVEC) (Fig.
1a). Plk4 regulates centriole duplication, and its overexpression downstream of a TRE (tet-responsive element) upon addition of doxycycline (DOX) results in supernumerary centrosomes [
13,
17,
24,
25]. TRE-Plk4 HUVEC were seeded onto large H-shaped micropatterns that allow for polarity assessment between two EC that form a cell–cell junction. Polarity was defined based on centrosome position relative to the nucleus and cell–cell junction, with a “proximal” position being near the cell–cell junction, a “central” position in the nuclear region, and a “distal” position between the nucleus and the cell periphery (Fig.
1b). Two EC with a normal centrosome number (1–2) typically had a distal centrosome polarity (Fig.
1c-d). In contrast, two EC with excess centrosomes (> 2) showed a significant increase in central/proximal polarity, indicating that centrosome number affects EC polarization relative to cell–cell junctions (Fig.
1c, d). Interestingly, when a normal EC and an EC with excess centrosomes were linked on the same pattern (N:O), normal EC had a higher frequency of aberrant centrosome localization than N:N counterparts, while EC with excess centrosomes had a higher frequency of normal centrosome localization relative to O:O counterparts, suggesting that EC polarity influences polarity in neighboring cells (Fig.
1d). Furthermore, when two EC with normal centrosome number (N:N) formed a junction, both cells usually had centrosomes in the distal position, which we termed “distal” polarity (Fig.
1e). All other polarity combinations were deemed “other”. When both EC forming a junction had excess centrosomes (O:O), polarity was randomized between distal and other (Fig.
1e). Additionally, N:N EC combinations were more likely to have cells with matching polarity, while EC with an O:O combination were less likely to have the same polarity as their neighbor (Fig.
1f). Taken together, these data indicate that excess centrosomes prevent proper EC polarization relative to cell–cell junctions.