Fig. 4.

Distinct effects of SP600125 and GK2 on TJ formation in HaCaT cells. a upper, Accumulation of a TJ component ZO-1 (red) in cells with SP600125 and GK2 on day 1 (left) and day3 (right). The nuclei were counterstained with DAPI. Bars, 25 μm. Lower, quantification of relative number of TJs on day 1 and 3. Average numbers of TJs from three line scan assays (n = 3 for each category, as shown in Figs. 1 and 3) were calculated and relative numbers to those of day1 are shown. TJs induced by SP600125 appeared to be stable, whereas those by GK2 were almost disrupted on day 3. Bars, 50 μm. b Comparative diagram of TJ-formed cell populations in HaCaT keratinocytes treated with SP600125 and GK2. Cells treated with GK2 construct double cell layers and only upper cells formed TJs (see Figs. 1 and 3). c Schema of the effect of GK2 on HaCaT cells that produce an inflammatory mediator HMGB1. GK2 abrogates the inflammatory action of HMGB1, leading to restoration of the differentiation potential and of the TJ formation program