Skin

Skin

1. Role of skin

   • Protection
   • Sensation
   • Thermoregulation
   • Metabolic

2. Epidermal layers

   • Cornified layer
     • Cornified envelope
       • Filaggrin
         • In disease
           • FLG gene mutation
             • Ichyosis vulgaris
         • Gene structure
           • N terminal regulated enucleation
           • Repeat segment = keratin bundling
           • C terminal required for processing
         • Processing
           • Stage 5: Fillagrin degraded by caspase 14
             • N product amino acids as moisturisers
           • Stage 1: Profiligrin in keratohyalin
           • Stage 2: Rising Ca2+ starts processing
             • Fillagrin releases
           • Stage 3: Matriptase & prostasin
             • Fillagrin processed
           • Stage 4: Mature fillagrin bundles keratin
       • Assembly
         • Initial scaffold
           • Periplakin
           • Envoplakin
             • Triple KO
               • Affects cornified envelope
               • Poor lipid
               • Reduction in proteases
           • Involucrin
           • Transglutaminase 1
         • 2ndary
           • Loricrin
           • SPRR
           • Transglutaminase 3
     • Lipid envelope
       • Importance
         • ABCA12 mutation
           • Harlequin Ichtyosis
           • Lipid transporter
     • Intercellular lamellae
       • Secreted by lamellar bodies
   • Granular layer
     • Keratinocyte differentiation
       • Lose nucleus and organelles
       • secrete phospholipids
         • ceramide lipids
     • Tight junctions
       • Claudin1 deficiency
         • loss of water & TJ
   • Spinous layer
   • Basal layer