Fig. 6

Intermediate Proteins Nok and Pard6 Stabilize the PAAs

(A) Transverse imaging: In 26-ss nok^m520 single and nok^m520/pard6γb^fh266 double mutants, ZO-1 and N-Cad^wt-GFP aggregated in clusters (arrows) at the midline region, compared with the regular distribution of the PAAs in 26-ss wild-type. In 26-ss pard6γb^fh266 mutants, the PAAs contoured small luminal sacs.

(B) Sagittal imaging: As summarized by the drawings on the right, in 26-ss wild-type embryos, ZO-1 and N-Cad^wt-GFP enriched at the PAAs as circumferential belts; by contrast, in 26-ss nok^m520 mutants, ZO-1 and N-Cad^wt-GFP clustered at the corners of the cells, indicating the loss of PAA integrity.

(C) ZO-1 and N-Cad^wt-GFP distributions (top panels, transverse imaging; bottom panels, sagittal imaging) in DMSO-treated and DNA-synthesis-inhibitor-treated wild-type and nok^m520 mutants (6 wild-type and 12 mutant embryos for each condition). Note that inhibitor treatment of nok^m520 mutants restored intact PAAs and miniature lumens (inset, arrow miniature lumens) and prevented cellular bridges (arrows cellular bridges).

(D) TEM: Unlike in wild-type, where the PAAs sealed the paracellular clefts near the lumen (arrows), cell-cell junctional complexes clustered at membrane protrusions in nok^m520 and indiscriminately adhered cells from both sides together at 26-ss (double arrowheads). Arrow BB, basal body.

(E) A scheme depicts that Nok is required to maintain the PAAs during cell proliferation. Inhbt., DNA synthesis inhibitors. Also see Figure S6.