Dermatology Basic Science Flashcards
Desmosomes anchor to what.
Keratins
Desmosomes are consist of what. Which are cytoplasmic and which are transmembrane
Transmembrane: desmocollin1/2/3, desmoglein 1/3
Cytoplasmic: desmoplakin, plakoglobin, plakophilin
What mineral is desmocollin, desmoglein and other cadherins dependent on?
Calcium
What are the 4 types of ways keratinocytes connect to each other?
Desmosomes, adherens, tight junctions, gap junction
Adherins junctions attach to what?
Actin filaments
What do adherens junctions consist of? Which is transmembrane and which is cytoplasmic?
Transmembrane: Classic cadherins (E and P)
Cytoplasmic: alpha catenin, beta catenin
What are tight junctions composed of? And where are they?
Granular Layer. Composed of claudins and occludins. Form tight seal against water loss
What are gap junctions composed of?
connexons. for intercellular ocmmunication.
What keratins are at the basal layer
Keratin 5/14
Increased keratinocyte proliferation is associated with what enzyme? What other factors?
UV, trauma, increased expression of ornithine decarboxylase
Ornithine decarboxylase is inhibited by what 3 things?
corticosteroid, retinoids and vitamin D3
How many days from basal layer to desquamation?
28 days
What keratins are in the stratum spinosum?
Keratin 1 and 10
What causes terminal keratinocyte differentiation in the stratum spinosum
increased intracellular calcium
Cornified cell envelope: Most important lipid? Protein?
Most important lipid is ceramide. Most important protein is loricrin (makes up 80% mass of CE).
Components of keratohyaline granules?
Loricrin, Profillagrin (converted to fillaggrin at the junction of stratum granulosum and stratum corneum), keratin intermediate filaments, involucrin
What enzyme cross links loricrin?
Transglutaminase 1, which is mutated in lamellar ichthyosis. *transglutaminase 3 is targeted in dermatitis herpetiformis
What protein is in both desmosomes and adherens?
Plakoglobin (which is part of the armadillo family)
Desmoglein 1 is affected in what disease states?
Striate PPK, PF, + (PNP, PV, IgA pemphigus) Bullous impetigo, SSSS. (in parenthesis also see in desmoglein 3 mutation)
Desmoglein 4 is affected in what disease states?
Monilethrix (AR), autosomal recessive hypotrichosis
Desmocollin 1 is mutated in what disease states?
IgA pemphigus (SPD type)
Plakoglobin is mutated in what disease states?
Naxos Syndrome
Desmoplakin is mutated what disease states?
Carvajal Syndrome
Beta catenin mutated in?
pilomatricomas seen in myotonic distrophy and Rubenstein-Taybi
Erythrokeratoderma varriabilis mutations in what protein?
Connexin 30.3 and 31
Hidrotic ectodermal dysplasia mutations in what protein?
Connexin 30
Connexin 26 mutations in what diseases?
KID, Bart-Pumphrey, PPK w deafness, Vohwinkel
Keratins
intermediate filaments
Type 1 keratins are low molecular weight keratins. Acidity? Keratin numbers? Chromosome #?
Low-MW Acidic, K9-28, K31-40. Chromosome 17
Type 2 keratins are high molecular weight keratins. Acidity? Keratin numbers? Chromosome #?
High MW. Basic K1-8, K81-86. Chromosome 12
What is the functional unit of a keratin?
Functional unit consist of heterodimers of type 1 and type II filaments that form tetramers and ultimately filaments
Melanocytes are derived from from what cells?
Neural crest cells
Each melanocyte interfaces with how many keratinocytes?
36 (epidermal melanin unit)
Tyrosinase is dependent on what mineral?
Copper
Describe pheomelanin and eumelanin. Melanosome size and colors they make.
Pheomelanin makes yellow/red. Made by round melanosomes. Eumelanin makes black/brown via elliptical melanosomes.
What causes the red hair/fair skin phenotype?
MC1-R loss of function mutation causing increased pheomelanin:eumelanin ratio.
How does skin immediately tan?
Through oxidation of existing melanin
Defects of tyrosinase, packaging of melanosome-specific proteins, lysosome/melanosome trafficking to dendrites cause which diseases?
OCA (oca1 tyrosinase, oca2 p gene, oca3 trp-1). Hermansky-Pudlak (Defects in packaging of melanosome specific proteins). Griscelli + Chediak Higashi are defects in lysosome and melanosome trafficking to dendrites.
Langerhan cell immunostains
CD 207 (langerin, which is the most sensitive and specific), CD1a, S100, CD34 (originate from CD34+ progenitor cells in bone marrow like other monocytes/macrophages), vimentin and actin
Merkel cells are ___. Found in ____.
Merkel cells are slow-adapting mechanoreceptos found in fingertips, lips, oral cavity, hair follicle ORS. Found in stratum basale.
Merkel cell stains for
CK 20+ perinuclear dot, neurofilament, S100, synaptophysin, chromogranin A, VIP, neuron specific enolase and calcitonin gene-related peptide
Lamina Lucida consists of what 3 proteins?
BPAG 2 (collagen 17, BP180), a6b4 integrin, laminin 332 (aka laminin 5, epiligrin)