Figure 1.
Expression of keratin genes in the stratified epithelium of the epidermis.
As keratinocytes become post-mitotic and migrate through the epidermis from the basal into the spinous layer, KRT1 and KRT10 expression is up-regulated, replacing the expression of KRT5 and KRT14 [28], [29]. These expression changes are controlled at the transcriptional level [30], [31]. During terminal differentiation the keratinocytes migrate into the granular layer, and KRT1 and KRT10 are replaced by K2e [29]. During re-epithelialization in the wounded epidermis, cells preparing to migrate down-regulate KRT1 and KRT10 in favour of KRT6, KRT16, and KRT17 [2], [3]. The repression of KRT1 is thought to be necessary for normal terminal differentiation and migration [28], [29]. The figure is adapted from Porter and Lane [29].
Figure 2.
Characterization of KRT1 protein expression in HEK cells.
a. Western blot analysis using anti-KRT1 antibody, with the left and right lanes containing proteins isolated from cells homozygous for the KRT1 haplotype patterns H1 (sample 8 in Table 3) and H2 (sample 9 in Table 3) respectively. Replicate gels stained with Coomassie blue demonstrate equal levels of proteins loaded for the HEK samples. All six HEK samples examined contained similar levels of KRT1 protein. b. Immunohistochemistry showing distribution of KRT1 protein in two of the three confluent HEK samples examined. A subset of the anti-KRT1 cells displays strong membrane staining, while the remaining cells display low to moderate level membrane staining. Staining of the nucleus is present at the same level in the anti-KRT1 and negative control cells. All three HEK samples examined display similar KRT1 expression patterns.
Figure 3.
a. HEK cells were stained with BrdU five hours after wounding. The number of BrdU-positive cells observed at the wound area was roughly equal to the number observed within the monolayer (98±6), indicating that the two areas had approximately the same amount of cell proliferation. b. Migration of HEK cells in response to wounding. Digital photographs taken at the same positions at the time-points indicated show the migration of HEK cells into the cell-free areas of the artificial wound sites. Examples from cell-lines homozygous for KRT1 haplotype patterns H1 and H2 are shown. The cell-free areas are given as a fraction of the 638 µm×956 µm area shown (the visible grid-lines are 175 µm apart). The cell-free areas from eight replicates are used to calculate the migration rate of each sample (see Methods).
Table 1.
KRT1 haplotype patterns in HEK cells.
Table 2.
Linear regression analysis of SNPs in the KRT1 interval on HEK cell migration rate.
Table 3.
KRT1-interval SNP1 genotypes, haplotype patterns and cell migration rates of the 41 HEK samples.