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Targeted Disruption of the Lama3 Gene in Adult Mice Is Sufficient to Induce Skin Inflammation and Fibrosis Monika Pesch, Sabrina König, Monique Aumailley Journal of Investigative Dermatology Volume 137, Issue 2, Pages (February 2017) DOI: /j.jid Copyright © 2016 The Authors Terms and Conditions
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Figure 1 Nail defects in Lama3flox/flox/K14-CreERT mice after tamoxifen-containing diet (11 weeks). Paws of a homozygous Lama3flox/flox/K14-CreERT (eKO) mouse with blisters, erosions, and nail defects (one nail is lost on the front paw and several nails on front and back paws are partially uprooted). Paws of a tamoxifen-treated heterozygous Lama3wt/flox/K14-CreERT control (Ctr) mouse are normal. Ctr, control; eKO, Lama3flox/flox/K14-CreERT. Journal of Investigative Dermatology , DOI: ( /j.jid ) Copyright © 2016 The Authors Terms and Conditions
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Figure 2 LMa3 chain is absent along the IFE of tamoxifen-treated Lama3flox/flox/K14-CreERT mice. Immunofluorescence staining of the LMα3 chain (red) and collagen IV (green) were performed on skin cryosections of homozygous Lama3flox/flox/K14-CreERT (eKO) and heterozygous Lama3wt/flox/K14-CreERT (Ctr) mice after 11 weeks of tamoxifen-containing diet. Cell nuclei were stained with DAPI (blue). Stained LMα3 chain is shown alone (left pictures) or superimposed with collagen IV and DAPI staining (right pictures). In eKO, the dotted lines delineate blisters and arrow heads indicate remnants of LMα3 chain-containing laminins. Scale bar = 50 μm. Col, collagen; Ctr, control; d, dermis; e, epidermis; eKO, Lama3flox/flox/K14-CreERT; hf, hair follicle. Journal of Investigative Dermatology , DOI: ( /j.jid ) Copyright © 2016 The Authors Terms and Conditions
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Figure 3 Gradual loss of LM-332 in the skin of tamoxifen-treated Lama3flox/flox/K14-CreERT mice. After 8, 11, and 15 weeks of tamoxifen treatment, proteins were extracted from the skin of homozygous Lama3flox/flox/K14-CreERT (eKO) and heterozygous Lama3wt/flox/K14-CreERT (Ctr) mice, fractionated in duplicate by SDS-PAGE under reducing conditions, and immunoblotted with antibodies against the LMγ1 and LMγ2 chains as indicated. The amounts of deposited LM-332 (indicated by the amounts of the processed 105 kDa LMγ2 chain) decrease progressively in eKO skin, whereas the amounts of the LMγ1 chain remain unchanged. Band intensity measurements indicate that the processed LMγ2 chain (105 kDa) is reduced to 35%, 28%, and 4% in eKO compared with controls after 8, 11, and 15 weeks, respectively, of tamoxifen. Ctr, control; eKO, Lama3flox/flox/K14-CreERT; IB, immunoblotting. Journal of Investigative Dermatology , DOI: ( /j.jid ) Copyright © 2016 The Authors Terms and Conditions
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Figure 4 The localization of LM-332 ligands indicates subepidermal blistering in tamoxifen-treated Lama3flox/flox/K14-CreERT mice. Homozygous Lama3flox/flox/K14-CreERT (eKO) and heterozygous Lama3wt/flox/K14-CreERT control mice (Ctr) were treated with tamoxifen (11 weeks). Back skin cryosections were immunostained for collagen VII (green) and integrin α6 subunit (red). Both proteins show a linear staining along the interfollicular and follicular epidermal-dermal junction of Ctr skin. In homozygous eKO mice, abundant collagen VII deposits (green color) are scattered in the repair tissue partially or totally filling the blistered areas. In addition, some collagen VII co-localizes (yellow color) with α6 integrin at the ventral surface of basal keratinocytes, even in blistered areas (arrow). Cell nuclei are stained with DAPI (blue). Left scale bar = 100 μm; right scale bar = 50 μm. Col, collagen; Ctr, control; d, dermis; e, epidermis; eKO, Lama3flox/flox/K14-CreERT; hf, hair follicle; Itg, integrin. Journal of Investigative Dermatology , DOI: ( /j.jid ) Copyright © 2016 The Authors Terms and Conditions
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Figure 5 Skin thickening and accumulation of collagen in the dermis of tamoxifen-treated Lama3flox/flox/K14-CreERT mice. (a) Hematoxylin and eosin staining of back skin showing detachment of the interfollicular epidermis in an eKO mouse, whereas the dermal-epidermal junction is intact in a heterozygous Ctr mouse. Dermal thickness is enlarged in eKO with Ctr, and repair tissue is partially filling blister cavities. The orientation of hair follicles is perpendicular to the skin surface in homozygous eKO mouse and oblique for the Ctr mouse. Scale bar = 100 μm. (b) Back skin cryosections from Lama3flox/flox/K14-CreERT (eKO) and Lama3wt/flox/K14-CreERT (Ctr) mice treated with tamoxifen (11 weeks) were stained with picrosirius red and observed with (left) transmitted and (right) polarized light microscopy. Collagen (yellow brackets) accumulates in the thick dermis of eKO mice. Scale bar = 100 μm. (c) Skin extracts from eKO and Ctr mice were fractionated in duplicate by SDS-PAGE under reducing conditions and immunoblotted with antibodies against (left) collagen VI or (right) nidogen as indicated. Actin was immunoblotted to verify loading. Representative blots are shown. (d) Graph shows quantification of the collagen VI chains, which are increased in eKO compared with Ctr skin (set as 1). Each column represents the average value calculated from three mice. Standard deviation is shown. Ctr, control; eKO, Lama3flox/flox/K14-CreERT. Journal of Investigative Dermatology , DOI: ( /j.jid ) Copyright © 2016 The Authors Terms and Conditions
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Figure 6 Abundance of myofibroblasts, macrophages, and granulocytes in the skin of tamoxifen-treated Lama3flox/flox/K14-CreERT mice. At the end of 11 weeks of tamoxifen-containing diet, back skin cryosections from homozygous Lama3flox/flox/K14-CreERT (eKO) and heterozygous Lama3wt/flox/K14-CreERT control mice (Ctr) were stained with antibodies against α-smooth cell actin (α-SMA, red), granulocytes (Gr-1, green) and macrophages (F4-80, green). Cell nuclei are stained with DAPI (blue). All three types of cells accumulate in the dermis of eKO mice. Upper panel scale bars = 100 μm; middle and bottom panel scale bars = 40 μm. Ctr, control; eKO, Lama3flox/flox/K14-CreERT. Journal of Investigative Dermatology , DOI: ( /j.jid ) Copyright © 2016 The Authors Terms and Conditions
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