DSG1

DSG1 (desmoglein 1) is a desmosomal cadherin that mediates calcium-dependent intercellular adhesion in stratified epithelia, organized in an increasing basal-to-granular gradient across epidermal layers (PMID:35711465). Its cytoplasmic domain engages plakoglobin through a 19-amino acid sequence homologous to the catenin-binding domain of classical cadherins, providing a shared molecular basis for plakoglobin recruitment to desmosomes and adherens junctions (PMID:8188687). Beyond structural adhesion, an extradesmosomal pool of DSG1 co-localizes with plakoglobin throughout the epidermis, and this association is lost in pemphigus patient skin, implicating DSG1 in desmosome assembly (PMID:35711465). DSG1 is the target of pemphigus foliaceus autoantibodies, which drive EGFR-independent Ca2+ influx and loss of keratinocyte cohesion, distinct from the Src/EGFR-dependent mechanism of anti-DSG3 pemphigus vulgaris antibodies (PMID:31178865). Domain-resolved patient analyses establish a structure-function map: loss-of-function variants in the extracellular or transmembrane domains abolish surface DSG1 and intercellular adhesion, whereas intracellular-domain variants partially preserve adhesive function (PMID:41781296), and intronic variants can cause loss of function via aberrant splicing and nonsense-mediated decay (PMID:33818390).

1. 1994 Medium

   Established how DSG1 connects to the cytoskeletal/junctional plaque by mapping the cytoplasmic determinant for plakoglobin binding, unifying desmosomal and adherens-junction adhesion mechanisms.

   Evidence Blot overlay binding assay with a deletion series of the DSG1 cytoplasmic domain as fusion proteins

   PMID:8188687

   Open questions at the time

   • In vitro binding only; affinity and stoichiometry in intact desmosomes not defined
   • Does not address how this binding is regulated in vivo
2. 1994 Medium

   Defined the genomic architecture of DSG1 and showed conservation of ectodomain exon boundaries with classical cadherins, localizing a polymorphic region to a topological position equivalent to an adhesion-disrupting cadherin epitope.

   Evidence Genomic cloning, restriction mapping, and comparative exon-structure analysis of the bovine DSG1 gene

   PMID:8294446

   Open questions at the time

   • Functional consequence of the identified polymorphism not tested
   • Bovine gene; human exon structure inferred by homology
3. 2019 Medium

   Distinguished DSG1-directed from DSG3-directed pemphigus signaling by showing PF-IgG drives EGFR-independent Ca2+ influx, separating the two autoantibody mechanisms.

   Evidence CRISPR/Cas9 Dsg3/Dsg2 knockout HaCaT keratinocytes with Ca2+ chelation, EGFR inhibition, and adhesion readouts

   PMID:31178865

   Open questions at the time

   • Identity of the Ca2+ channel and downstream effectors not resolved
   • Single keratinocyte line; not validated in patient tissue
4. 2022 Medium

   Revealed that DSG1 has an extradesmosomal, plakoglobin-associated pool and a layer-specific distribution gradient that is disrupted in pemphigus, supporting a role in desmosome assembly beyond adhesion.

   Evidence Super-resolution STORM/STED co-localization of DSG1, DSG3, desmoplakin, and plakoglobin in healthy and pemphigus skin

   PMID:35711465

   Open questions at the time

   • Functional role of the extradesmosomal pool in assembly not directly tested
   • Co-localization does not establish direct binding in situ
5. 2021 Medium

   Demonstrated that non-coding DSG1 variants can cause loss of function, expanding the mutational mechanisms beyond coding changes.

   Evidence Mini-gene exon-trap splicing assay with NGS and cDNA analysis of a deep-intronic variant

   PMID:33818390

   Open questions at the time

   • Quantitative impact on residual protein not measured
   • Single variant; generality across introns unknown
6. 2026 Medium

   Provided a domain-resolved structure-function map linking variant location to adhesive outcome: ectodomain/transmembrane loss abolishes surface DSG1 while intracellular variants retain partial function.

   Evidence Immunofluorescence of DSG1 in skin of SAM syndrome patients with characterized variants

   PMID:41781296

   Open questions at the time

   • Mechanism of residual function for intracellular variants not dissected
   • Adhesion quantified indirectly via staining, not biophysical assay
7. 2025 Low

   Implicated SOCE/Ca2+ signaling in DSG1 regulation by linking STIM1/2 loss to altered DSG1 and elevated kallikrein protease activity with barrier defects.

   Evidence Epithelial Stim1/2 conditional knockout mice, RNA-seq, protease activity and barrier assays (preprint)

   Open questions at the time

   • Correlative; direct Klk-mediated DSG1 proteolysis not demonstrated
   • Preprint, single lab
   • DSG1 not the direct subject of mechanistic dissection
8. 2024 Low

   Identified EFNA3 as an upstream inducer of DSG1 expression supporting epithelial barrier integrity in vaginal epithelium.

   Evidence Topical recombinant EFNA3 in DMPA-treated mice with DSG1 expression and barrier/HSV-2 infection readouts (preprint)

   Open questions at the time

   • Regulatory link inferred from expression changes, not direct mechanism
   • Preprint, single lab
   • Pathway connecting EFNA3 to DSG1 unknown
9. 2025 Low

   Showed that anti-DSG1/3 antibody binding alone does not trigger downstream transcriptomic/proteomic changes; physical adhesion disruption is required to drive inflammatory signaling.

   Evidence Human skin organ culture pemphigus model with anti-DSG1/3 scFv (PX43), transcriptome/proteome profiling (preprint)

   Open questions at the time

   • Negative result; does not exclude rapid pre-detachment signaling
   • Preprint, single lab
   • Does not isolate DSG1-specific from DSG3-specific effects

• The molecular events linking DSG1 ectodomain engagement to Ca2+ influx and to desmosome assembly versus disassembly remain undefined.
• No identified Ca2+ channel mediating PF-IgG response
• No structural model of the DSG1-plakoglobin interface in situ
• Mechanism coupling extradesmosomal DSG1 to assembly unresolved