The cytoskeleton is a network of scaffolding that gives cells their shape. The cytoskeleton is made up of intermediate filaments, microtubules, actin, and myosin. Microtubules are cylinders of tubulin that can dynamically assemble and disassemble to change length. Microtubules are very important for multiple types of cellular movement (Mitosis, Axonal Trafficking, Cilia/Flagella…). Motor proteins Dynein and Kinesin travel along microtubules like trains on a track causing these movements. Microtubule functioning is inhibited by drugs like Colchicine (gout), Vincristine (cancer), Paclitaxel (cancer) and Mebendazole (parasites).
Kartagener’s Syndrome (Primary Ciliary Dyskinesia) is a genetic defect in Dynein motor proteins that prevents proper functioning of the Cilia. Cilia normally beat in a rhythmic wave forcing foreign material out of the body. Immotile cilia in the sinuses, ear, and respiratory tract result in Recurrent Infections (sinusitis, otitis media, pneumonia & bronchitis). Abnormal cilia also lead to Infertility in men (immotile sperm) and women (vaginal mucus builds up and is too thick).
Chediak Higashi is a genetic defect in phagocyte microtubules which fuse the phagosome and lysosome. The defect prevents phagocytes from destroying what they engulf and Giant Granules of undigested material builds up. This causes Recurrent Infection (impaired phagocyte function), Albinism (impaired melanin trafficking) & peripheral neuropathy (impaired axonal transport).
I-Cell Disease (Inclusion-Cell Disease) is a genetic defect which limits the ability to phosphorylate mannose in the golgi and leads to abnormal cellular trafficking. Mannose-6-Phosphate usually signals newly made enzymes to be delivered to the lysosome. Without this signal these enzymes meant for the lysosome follow the “default” trafficking pathway and are secreted outside of the cell (into the extracellular matrix) damaging other cells. Patients present with lysosomal enzyme deficiencies and the presence of Lysosomal Enzymes Where They Shouldn’t Be (Blood, Urine…). This leads to a wide variety of symptoms such as Abnormal Facial Features, joint problems, and short stature. Additionally, lysosomes cannot function properly in degrading cellular debris which causes accumulation of cellular debris in the lysosome and the formations of inclusions bodies.
Now that you are done with this video you should check out the next video in the Biochem section which covers Marfan Syndrome, Osteogensis Imperfecta & Ehlers Danlos.
Pictures Used (In order of Appearance)
- This work is a derivative of “Microtubules and Alkaloids” by Simon Caulton available at http://commons.wikimedia.org/wiki/File:Microtubules_and_alkaloids.png under Attribution-Share Alike Creative Commons 3.0
- This work is a derivative of “Spindle Aparatus” by Lordjuppiter available at http://en.wikipedia.org/wiki/File:Spindle_apparatus.svg under Attribution-Share Alike Creative Commons 3.0
- This work is a derivative of “Kartagner” by Filip Em available at http://en.wikipedia.org/wiki/File:Kartagener.svg under Attribution-Share Alike Creative Commons 2.5
- This work is a derivative of “Alpha-Mannosidosis Electron Micrograph” by Dag Malm and Øivind Nilssen available at http://en.wikipedia.org/wiki/File:Alpha-mannosidosis_electron_micrograph.JPEG under Attribution Creative Commons Generic 2.0