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Loss of Cell Adhesion in Dsg3bal–Pas Mice with Homozygous Deletion Mutation (2079del14) in the Desmoglein 3 Gene Leena Pulkkinen, Yoo Won Choi, Anisha Simpson, Jouni Uitto, Mỹ G. Mahoney, Phd. Journal of Investigative Dermatology Volume 119, Issue 6, Pages (December 2002) DOI: /j x Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions
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Figure 1 Development of hair and skin phenotype in Dsg3bal–Pasmice. Note visible patchy hair loss from head to rear (A) and erosion of the conjunctiva (B). Journal of Investigative Dermatology , DOI: ( /j x) Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions
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Figure 2 Expression of desmosomal cadherins in neonatal Dsg3bal–Pasmice. Immunofluorescence of oral mucosa of homozygous Dsg3bal–Pas (B,D) mouse compared with +/Dsg3bal–Pas control littermate (A,C) for Dsg3 (A,B) and Dsg1 and Dsg2 (C,D). Note the absent of Dsg3 expression in the homozygous Dsg3bal–Pas epithelium (B). Journal of Investigative Dermatology , DOI: ( /j x) Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions
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Figure 3 Analysis of the Dsg3 mutation in Dsg3bal–Pasmice. Heteroduplex analysis of the PCR-amplified fragment spanning exon 13 and flanking intronic sequences (A). The control DNA gave a single homoduplex band (lane 3), the Dsg3bal–Pas gave a single more rapidly migrating band (lane 1), whereas the mixture gave a duplex of both bands (lane 2). Sequence analysis of the PCR product shows a deletion of 14 nucleotides at position 2079 of Dsg3 (B, left panel) in the homozygous Dsg3bal–Pas mouse compared with the normal sequence (B, right panel). The heterozygous PCR product revealed both sequences (B, middle panel). Journal of Investigative Dermatology , DOI: ( /j x) Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions
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Figure 4 Schematic comparison of the different Dsg3 molecular domains of normal, Dsg3bal–Pas, and Dsg3bal–2Jmice. The specific domains and their corresponding number of amino acids are indicated. The BalPas Dsg3 contains 693 amino acids and two missense amino acids. whereas the Dsg3bal–2J Dsg3 contains 758 amino acids and 26 missense amino acids. The individual domains are as follows: SP, signal peptide; E1–E4, extracellular repeating units; EA, extracellular anchoring domain; TM, transmembrane domain; IA, intracellular anchoring domain; ICS, intracellular cadherin-typical segment; LD, intracellular linker domain; RUD, intracellular repeated unit domain (two repeated units); TD, terminal domain. Arrows identify points of deletion (Dsg3bal–Pas) or insertion (Dsg3bal–2J) within the mutated Dsg3. Hatched box marks missense amino acids. Journal of Investigative Dermatology , DOI: ( /j x) Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions
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Figure 5 Presence of Dsg3 mRNA in the Dsg3bal–Pasmouse skin. Schematic presentation of the exons and introns of mouse Dsg3 gene corresponding to exons 9–15, drawn to scale with introns as solid lines and exons boxed (A). Asterisk marks the site of the deletion mutation in Dsg3bal–Pas mouse. Total RNA was extracted from the skin of adult control and homozygous Dsg3bal–Pas mice (B). Amplification by PCR of a region spanning nucleotides 1881–2518 resulted in a predominant product (band a, 638 bp) in the control mouse and two products (bands b and c, slightly lower in size) in the homozygous Dsg3bal–Pas mouse. The schematic diagram of the reverse transcription–PCR result shows wild-type splicing of introns 12 and 13 presented as solid lines above the gene and alternative aberrant splicing of the mutated pre-mRNA is indicated as dashed lines below the gene (C). Schematic presentation of the gene products (a–c) is also shown. Journal of Investigative Dermatology , DOI: ( /j x) Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions
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Figure 6 Expression of full-length and truncated Dsg3 in HaCaT cells. HaCaT cells were transiently transfected overnight with the Dsg3T.myc, fixed in methanol, and immunostained for the myc tag (A–F,I–P). Cells expressing Dsg3T.myc showed cell border (A,E, arrowheads) as well as cytoplasmic, mostly perinuclear, staining (A,C,E). Overexpression of Dsg3T.myc in some cells showed distinct aggregates in the cytoplasm (C, asterisk) and extensive network of filopodia (C,E, arrows). Staining for the myc tag are shown in red. Cells were counterstained with DAPI nuclear dye shown in blue (B,D,F). Immunofluorescence staining for the Flag tag in HaCaT cells expressing the full-length Dsg3.Flag (G). The same cells were counterstained with anti-plakoglobin antibodies (H). Dsg3.Flag did not affect expression and localization of plakoglobin. Jagged cell border staining was observed with the Dsg3T.myc, whereas sharp cell–cell border staining was observed with the Dsg3.Flag. HaCaT cells transfected with Dsg3T.myc and co-labeled with anti-myc (I,K,M) and anti-plakophilin 2 (J), anti-Dsg1 and anti-Dsg2 (L), anti-desmoplakin (N), or anti-plakoglobin (O). Double arrows in (J,L,N) demonstrate staining of plakophilin 2, Dsg1 and 2, and desmoplakin in control cells not expressing Dsg3T.myc. Journal of Investigative Dermatology , DOI: ( /j x) Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions
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Figure 7 Effect of truncated Dsg3 on partitioning of desmosomal proteins into the Triton-soluble and Triton-insoluble pools. HaCaT cells were transiently transfected overnight with the Dsg3T.myc and extracted with lysis buffer containing 1% Triton X-100 and fractionated into Triton-soluble and Triton-insoluble pools. Proteins were subjected to Western blotting analysis with antibodies against myc and the desmosomal proteins, Dsg1/Dsg2, Dsg3, desmocollin 3 (Dsc3), desmoplakin 1/2 (DPI/II), plakoglobin (plakoglobin), plakophilin 1 (PPI), and plakophilin 2 (PPII). The endogenous Dsg3 partitioned mainly in the Triton-insoluble pool, whereas the truncated Dsg3T.myc remained largely in the Triton-soluble pool. The transient expression of Dsg3T.myc slightly decreased the Triton-insoluble fraction, while increasing the Triton- soluble fraction of DPI/DPII and plakoglobin. Journal of Investigative Dermatology , DOI: ( /j x) Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions
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