Figure 2.

Integrin α11 cytoplasmic tail is not involved in cell adhesion but mediates focal adhesion formation, collagen reorganization, cell migration and cell proliferation. (A) Role of α11-tail in cell adhesion. _Huα11-WT, _Huα11-1171 and mock transfected cells (Mock) were allowed to attach on collagen I or fibronectin or BSA in serum-free conditions for 50 mins. Attached cells were fixed, stained with 0.1% crystal violet and absorbance was read at 595 nm. (B) Role of α11-tail in cell proliferation. _Huα11-WT, _Huα11-1171 and Mock cells were allowed to attach on collagen I or fibronectin in reduced serum condition for 24 hours. Attached cells were fixed, stained with 0.1% crystal violet and absorbance was read at 595 nm. (C) Role of α11 tail in focal adhesion formation. Cells were allowed to attach collagen I for 120 mins. Cells were fixed with 4% PFA and focal adhesions were imaged using TIRF microscopy and quantified. Scale bar: 10 µm. (D) Role of α11-tail in collagen reorganization. _Huα11-WT, _Huα11-1171 and Mock cells were mixed with collagen I solution and allowed to contract for 16 hours. Gel diameters were measured, and percentage of initial gel area was calculated. (E) Role of α11-tail in spheroid migration. Homospheroids of _Huα11-WT, _Huα11-1171 and Mock cells were embedded in collagen I gel and spheroid migration was quantified after 24 hours. Radial profile plot depicts the radial cell intensity from the center of the spheroid and the intensity of cells that have migrated beyond 400 µm was calculated. Scale bar: 200 µm. Data shown are pooled from triplicates of at least three independent experiments for cell attachment, cell proliferation and collagen gel contraction. Results were expressed as mean ± standard deviation of at least three replicates from one representative experiment of at least three independent experiments. Statistical significance was assessed by two tailed, unpaired t-tests and P-values are expressed as ***P < 0.001; **P < 0.01 and *P < 0.05.