Figure 4.

Induced Deletion of PKN2 In Vivo Decreases Mesodermal Proliferation and NCC Migration

(A–E) Tamoxifen was given on day 8 of pregnancy before embryo harvest at E10. Embryos were sectioned and stained for p-Histone H3 (pHistH3) to measure mitotic index and cleaved caspase 3 (cCasp3) to measure apoptotic index. (A) Aligned sections were counted to reveal a significant decrease in mitotic index in the pharyngeal mesoderm (pm) but not the branchial arches (ba), neural tube (nt), or heart (h) following PKN2 deletion in PKN2^fl/fl but not PKN2^fl/+ embryos (n = 3; ^∗p < 0.05). (B) Apoptosis was variably increased across all tissues but did not reach significance. (C and D) Examples of pHistH3 and cCasp3 section stains are displayed. (E) PKN2 loss results in collapse of the cephalic mesoderm (cm) as evidenced by hemorrhage (haem) and loss of cellularity.

(F) Whole-mount in situ staining reveals a deficit of migrating NCCs in PKN2 KO embryos. A single-WT and two KO embryos are presented; −/− # 1 has a partially closed neural tube, whereas −/− # 2 exhibits craniorachischisis. Vibratome sections reveal a deficit of NCCs and reduced ventral migration. Scale bars represent 100 μm.