Overexpression of Mmp2 in the CBs disrupts ECM, cell migration and lumen formation.

<p>UAS-<i>mmp2</i> transgene was expressed in the CBs under the control of <i>mef2</i>-GAL4. (A-A’) Filopodial, lamellopodial activities and outgrowth formation are not affected (arrows). However, alignment of the bilateral row of nuclei is disrupted (arrowheads). (B-B’) Multiple ectopic lumens form at the heart proper region when MMP2 is overexpressed (arrowheads). (C-D”) Embryos expressing <i>vkg</i>-GFP and <i>mef2</i>><i>moesin</i>-mCherry demonstrate the reduction of Vkg-GFP levels at the CB ECM in <i>mef2>mmp2</i> embryos relative to control (arrows). In control embryos, ECM localises at the pre-luminal (C,C’ arrowhead), luminal (C”, arrowhead) and basal domains (C-C”, diamonds). After Mmp2 overexpression, ECM is reduced at the pre-luminal (D,D’ arrowhead), luminal (D”, arrowhead) and basal domains (D-D”, diamonds) (C-D’, arrow indicates the dorsal midline). (E-F’) Embryos labelled with α-βPS and α-Mef2 reveal the disorganization of CBs at the heart proper in Mmp2 overexpressing hearts relative to control (arrows). In control embryos, Integrin localises to the pre-luminal (E’ arrowheads) and luminal domains (E,E”, arrowheads). In <i>mef2>mmp2</i> embryos, Integrin localises to the pre-luminal domain (F’, arrowheads) and ectopic lumens (F,F”, arrowhead). (G) Mean Vkg-GFP fluorescence intensity in control and Mmp2 overexpressing embryos for junctional, luminal and basal domains. Junctional, luminal and basal fluorescence intensity, respectively, differ significantly in Mmp2 overexpressing embryo compared to both controls as determined by one-tailed T test. ***—p<0.001. Scale– 10 μm.