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Lecture 20

BIOL 355 Lecture 20: Lecture 20

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BIOL 355
Dr.Cheryl Duxbury

Lecture 20 What are they, what is their role in aging? Consist of strongly crosslinked molecules (lipids, proteins, DNA) Cannot be broken down by lysosomes cellular garbage Very insoluble Stored lysosomes or shunted out to cytoplasm where accumulates Can make up to 30 of cytoplasm volume in old cells Most common in postmitotic cells Neurons Muscles (cardiac) Brain Older cell with 30 lipofuscin in cytoplasm and when cell division occurs both daughter cells will have 15 of lipofuscin Interfere with normal functioning by displacement? Loss of cytoplasm mass Loss of mitochondria (other organelles) Loss of RER (protein synthesis) Lipofuscin is a brownyellow material that accumulates progressively over time in lysosomes of post mitotic cells such as neurons and cardiac myocytes Some proposals about lipofuscin: It is incompletely degraded cellular waste Probably caused by increased cross linkage of cellular molecules Cause of aging? Displaces cellular organelles, stops their normal functioning Effect of aging? Lysosome age, decrease function, cant handle waste How do these molecules get Xlinked? AGE products Free radicals Fluorescence images of transverse frozen sections of quadriceps muscle. Images for lipofuscin analysis for 27month old vs 3month old mice Cross Linkage Theory
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