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Epithelial Cell Junctions

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Topic updated on 09/14/17 6:43pm

Overview
 

 
Snapshot
  • A 40-year-old woman presents with a pruritic rash of 2 weeks duration. She reports a persistent rash over her extremities with very itchy blisters that do not break easily. On physical exam, she has multiple 1-5 cm tense bullae on her abdomen and arms. Skin biopsy with direct immunofluorescence shows linear pattern of IgG and C3 deposits along the epidermal-dermal junction. (Bullous pemphigoid)
Tight Junction
  • Tight junction
    • also known as zonula occludens
    • location
      • between adjacent epithelial cells
    • composition
      • claudins
      • occludins
    • function
      • diffusion barrier between adjacent cells
      • prevents paracellular movement of solutes
      • maintains physiochemical separation of tissue compartments
Adherens Junction
  • Adherens junction
    • also known as belt desmosome, zonula adherens, and intermediate junctions
    • location
      • between adjacent epithelial cells
    • composition
      • e-cadherin
    • function
      • forms a belt that connects actin cytoskeletons to plasma membrane
      • actin filaments connect with E-cadherin
        • cadherins are Ca2+-dependent adhesion proteins
      • loss of E-cadherins promote metastasis
Desmosome
  • Desmosome
    • also known as spot desmosome and macula adherens
    • location
      • between adjacent epithelial cells
    • composition
      • desmoplakin
      • desmoglein
        • connects keratinocytes in stratum spinosum
      • desmocollin
    • function
      • structural support
      • couples intermediate filament to plasma membrane in adjacent cells
    • diseases
      • pemphigus vulgaris
        • autoantibodies target desmoglein component of desmosomes
Gap Junction
  • Gap junction
    • location
      • between adjacent epithelial cells
    • composition
      • connexons with central channel
    • function
      • forms channel for electrical and chemical communication between adjacent cells
      • permits exchange of ions, regulatory molecules, and small metabolites through pores
Hemidesmosome
  • Hemidesmosome
    • location
      • between epithelial cell and basement membrane
    • composition
      • integrin
    • function
      • connects epithelial cells to underlying basement membrane
      • integrins bind to laminin-5 and type IV collagen, attaching epithelial cell to extracellular matrix
    • diseases
      • bullous pemphigoid
        • autoantibodies target hemidesmosome


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Qbank (1 Questions)

TAG
(M1.MK.70) A scientist is studying the anatomy and function of bone growth. He is able to create a cell line of osteocytes with a mutation that prevents the osteocytes from exchanging nutrients and waste products within neighboring lamellae. This mutation most likely affected which of the following cell structures? Topic Review Topic

1. Gap junctions
2. Plasma membrane
3. Kinesin
4. Dynein
5. Endoplasmic reticulum

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