Effect of TIMP‐2 in trunk neural crest pathfinding

Previous studies suggest tissue inhibitor of metalloproteinase‐2 (TIMP‐2) plays a role in neural crest (NC) pathway choice. TIMP‐2 expression by cranial NC correlates positively with taking the dorsolateral pathway. However in the trunk where TIMP‐2 is not expressed in NC cells, NC cells initially take the ventromedial pathway. Here, we tested whether missexpression of TIMP‐2 in trunk NC cells redirects NC cell migration into the dorsolateral pathway. A bicistronic vector driving both TIMP‐2 and green fluorescent protein (GFP) expression or one lacking the TIMP‐2 sequence was introduced by in ovo electroporation into NC precursors at the future wing bud axial level. Embryos were then reincubated for 24 hr and those exhibiting GFP expression were fixed, immunostained as whole mounts for GFP and NC cells (HNK‐1 antibody), embedded, and sectioned. Pathway choice of trunk NC cells was scored as either taking the ventromedial, dorsolateral, or both. Results suggest miss‐expressing TIMP‐2 in trunk NC precursors promotes a dorsolateral pathway route. Whether TIMP‐2 missexpression redirects migration of all NCs or selectively promotes the early emigration of melanogenic NC precursor cells (that normally take the dorsolateral pathway later in development) is unknown and awaits further study. Supported by NIH (P20‐RR016469) from the INBRE Program of the National Center for Research Resources. Grant Funding Source : NIH (P20 ‐ RR016469 )