Intracellular scaffoldings & Cell talking Dr. Sadaf Mumtaz 12/12/11

Cytoskeleton Complex protein network portion of the cytosol

Microtubules

Microfilaments

Microvilli

Intermediate Filaments

Tissue typeIntermediate filament Epithelial cellskeratin Muscle cellsVimentin, desmin Neuron & Glial cellsPeripherin, neurofilaments DiseaseDefect Epidermolysis bulosa simplexAbnormal Keratin Amyotrophic lateral sclerosisAbnormal accumilation and disorganization of neurofilaments

MicrotubulesMicrofilamentsIntermediate filaments LargestSmallestIntermediate Unbranched, hollow tubes Twisted strandsThread like Composed of tubulinActin and myosinVarious protein composition Maintain asymmetric cell shapes Mechanical stiffnersMaintain structural integrity Co-ordinates numerous complex cell movements Play a role in ContractionResist mechanical stress

Microtrabecular Lattice

Cell – cell adhesions ECMDesmosomesTight junctionsGap Junctions Meshwork of fibrous proteins embedded in complex carbohydrates Anchor together two closely adjacent but non- touching cells Junctional proteins on the outer surface of the two interacting plasma membrane Adjacent cells are linked by connexons Secreted by local cells; fibroblast Consist of plaque & cadherin Impermeable juctional proteins Connexon consist of six protein subunits Composition varies: three major protein fibers (collagen, elastin, fibronectin) Found in uterus, heart, skin Found in sheets of epithelial tissues Found in cardiac muscle, smooth muscle, endothelial cells Not just a passive scaffold but helps regulate behaviour and functions of cell Attached to intermediate cytoskeletal filaments providing tensile strength Prevent undesirable leaks within the epithelial sheets Transmits electrical activity, signalling molecules, glucose, amino acids etc

ECM CollagenElastinFibronectin Forms cable like fibers/sheets Rubberlike protein fiber Protein dimers Tensile strengthStretching and recoil Promotes cell adhesion ScurvyInterstitial lung disease Cancerous cells (Reduced)

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