Figure 2. Epithelial Cells Follow Col-I Fiber Orientation in a Rac1 Dependent Manner in Culture.
(A) Method for axially orienting fibers within three-dimensional Col-I matrices.
(B–C) Confocal reflection micrographs of control (B) and oriented (C) Col-I matrices with the axis of orientation indicated (green arrows).
(D) Fiber alignment significantly increases upon compression. Values are represented as mean ± SEM; n = 10 matrices.
(E and F) Brightfield images of branching mammary explants in random (E) and oriented (F) Col-I matrices.
(G) Quantification of branch orientation between explants in control versus oriented Col-I matrices. Values are represented as mean ± SEM; n = 5 or 6 wells.
(H and I) Representative branching aggregates expressing vector alone (H) or a constitutively active form of Rac1 (I).
(J) Branch orientation was significantly disrupted in Rac1-CA-expressing aggregates in comparison to vector alone. Values are represented as mean ± SEM, n = 5 or 6 wells.
(K and L) Representative branching aggregates expressing vector alone (K) or fascin-1 (L).
(M) Branch orientation analysis showed a reproducible, although not significant, enhancement in branch orientation. Values are represented as mean ± SEM, n = 5 or 6 wells. The scale bars in (B), (C), (E), (F), (H), (I), (K), and (L) represent 50 μm.
See also Figure S2 and Movie S1.