Migration in vitro is enhanced in keratinocytes obtained from TRs deficient mice.

<p>(<b>A</b>) Representative images of scratch wound assays in primary cultures of newborn keratinocytes from Wt and TR KO mice. Confluent cultures were treated with mitomycin C (MMC) for 2 h before wounds were made. The right panel illustrates the rate of wound closure obtained in untreated and MMC treated cultures in both genotypes. (<b>B</b>) Representative images of dorsal skin explants from newborn Wt and TR KO mice treated with MMC and then incubated during 6 days in the presence and absence (Cont.) of EGF. In the right panel the number and size of keratinocyte foci migrating out of the explants in the presence and absence of MMC and EGF were quantitated. Data are shown as mean values ± SD, and asterisks denote statistically significant differences of Wt vs KO cultures. *, P<0.05; **, P<0.01; ***, P<0.001.</p

TR-deficient mice develop alopecia after serial depilation.

<p>(<b>A</b>) Wt and TR KO mice were depilated once a week and pictures were taken after 21 weeks. Quantification of anagen follicles (<b>B</b>) and follicular BrdU incorporation (<b>C</b>) in both groups at the end of the experiment. Data are shown as mean ± SE. *, <i>P</i><0.05.</p

Wound healing is retarded in mice lacking TRs.

<p>(<b>A</b>) Representative examples of wound closure in control and TR KO mice. Images were taken at the indicated times after wounding. (<b>B</b>) H&E staining 2 days after wounding. The black arrows indicate the end of the keratinocyte tongues. The main length of the tongues and the % of wound re-epithelialization are shown in the right panels. (<b>C</b>) 10 days after wounding BrdU positive cells were quantitated from histological sections at the wound edges in Wt and KO mice. Data are means ± SE. **, <i>P</i><0.01. (<b>D</b>) H&E staining of wounds at 10 days. The lower panels show a detail of H&E and picrosirius staining of the indicated areas. (<b>E</b>) Collagen fibers detected under polarized light of picrosirius staining in the unwounded tissue (left panels) and the wound centers (right panels).</p

Both TRα and TRβ are expressed in the mouse skin.

<p>Double immunofluorescence images of expression of keratin 14 (K14, green) with TRα or TRβ (red). Images were obtained from the interfollicular epidermis (IFE) and the hair follicles (HF) of wild-type mice. The slides were counterstained with DAPI (blue) and the merged images are shown. Bars: 50 µM.</p

Influence of TRs on hair growth.

<p>(<b>A</b>) Skin phenotype of wild-type (Wt) and TRα1^−/−/TRβ^−/− KO mice. (<b>B</b>) Immunohistochemical images of follicular BrdU incorporation in the dorsal skin of untreated Wt and TR KO mice and in mice depilated five days before. Larger magnifications of the hair follicles are also shown. (<b>C</b>) Proliferation rate of the follicular keratinocytes was quantified and is represented as the % of positive BrdU cells vs. total hair follicle cells. Percentage of hair follicles in anagen is shown in the lower panel. Data are shown as mean values ± SE, and asterisks denote statistically significant differences relative to Wt mice (*, P<0.05; **, P<0.05***, P<0.001). (<b>D</b>) Representative immunohistochemistry showing follicular expression of Cyclin D1 in depilated animals of both genotypes.</p

Hypothyroid mice and TR-deficient mice present similarly reduced proliferation in response to 9-cis-RA.

<p>Epidermal thickness (left panel) and BrdU incorporation (right panel) were determined in TR KO mice, mice treated with MMI and perchlorate for 4 months (hT) and in a group of animals receiving the anti-thyroidal drugs plus thyroxine (hT+T4).</p

TR deletion alters expression of loricrin.

<p>A) Localization by immunofluorescence of the terminal differentiation marker loricrin in the most external epidermal layer of skins from wild-type and TR KO mice treated with 9-cis-RA and TPA. Loricrin expression (red) demonstrates that 9-cis-RA (but not TPA) promotes altered differentiation and that this is more marked in mice lacking TRs. Panel B) shows that loricrin is totally absent in large areas of the skin of some TR KO animals after 9-cis-RA treatment.</p

Altered expression of proliferation-related proteins in the skin of TR-deficient mice after 9-cis-RA treatment.

<p>Total and nuclear skin cell lysates from Wt and KO mice treated topically with 9-cis-RA were used for Western blotting with the indicated antibodies. Actin and lamin B were used as a loading control for total and nuclear extracts, respectively.</p

Immune cell infiltration is enhanced in skins of TR deficient mice treated with 9-cis-RA.

<p>Double immunofluorescence images of keratin 5 (K5) with mac-1 (left panel), cd45 (middle panel) and cd3ε (right panel) in skins from wild-type and TR KO mice treated with 9-cis-RA or vehicle alone. Nuclei were stained with dapi.</p

Deletion of both TRα1 and TRβ is required to impair follicular proliferation and the anagen response to depilation.

<p>(<b>A</b>) Percentage of follicles in anagen growing phase and (<b>B</b>) Follicular BrdU incorporation, 5 days after exhaustive depilation. Experiments were assed in Wt animals, animals lacking both TRα1 and TRβ (KO), and in the individual KOs for TRα1 and TRβ (KOα1 and KOβ, respectively). Data are shown as mean values ± SE and the asterisk denotes a statistically significant difference (P<0.05) of KO vs Wt mice. Defective follicular proliferation and anagen response to depilation in hypothyroid mice. The percentage of hair follicles in anagen and BrdU incorporation in the follicular keratinocytes was quantified 5 days after depilation in Wt control mice (Ct), in mice made hypothyroid by treatment with antithyroidal drugs for 4 months (hT) and in a group of animals receiving the anti-thyroidal drugs plus thyroxine (hT+T4). A group of age-matched double KO mice were also used. Data are represented as the % of positive BrdU cells vs. total hair follicle cells. Data are shown as mean values ± SE, and asterisks denote statistically significant differences vs Ct mice. *, P<0.05; **, P<0.01.</p