BIOM20001 Lecture Notes - Lecture 41: Mitogen-Activated Protein Kinase, Adherens Junction, Cyclin-Dependent Kinase 4
Document Summary
Basal stem cells --> transit amplifying cells -->differentiating keratinocytes (produce keratin - desomosomes) --> lose nuclei (apoptosis) --> squames -->sloughed off. Apico-basal polarity integrins (fa, desmosomes), tight junctions, adherens junctions. Cell cycle control, dna damage (p53), normal death signals. Highly metastatic (melanocytes arise from neural crest cells in embryo. Regulates p53 activity and g1/s cdk/cyclin complexes (i. e. cdk4). Crypt stem cells provide new cells for a rapid turnover epithelium. Apc loh causes failure of cell migration, loss of cell fate, abnormal proliferation. Polyposis most commonly caused by mutation in apc (tumour suppressor) Progression of mutations: one mutation doesn"t do anything (maybe) --> two mutations cause increased prolif or decreased death --> third mutation and cell divides, doesn"t die, migrates. Cervical cells no longer look like cervical cells but more like stem cells. Substitution mutations of ras cause it to be hyperactive. K-ras one of the most commonly mutated genes in smoking related cancers.
