Your cells each contain thousands of distinct proteins, that each carry out a unique set of roles to maintain cellular function, as well as your overall health. Protein turnover -- the continued synthesis and processing of new proteins, as well as disposal of old proteins -- proves important to your overall health. The protein amyloid develops due to defects in normal protein turnover, and can harm your health.
APP and Amyloid
Amyloid protein is a diseased form of amyloid precursor protein, or APP. Healthy cells contain APP as part of their celular membranes, and the protein helps your nerve cells communicate and aids in the transport of iron across cell membranes to support cellular functioning. Amyloid accumulates with APP undergoes processing by enzymes called proteases, which cleave the protein to give rise to several variations of amyloid.
Amyloid and Toxicity
Once formed as a result of APP cleavage, amyloid has an effect on other cellular functions, and ultimately proves toxic to your cells. One way amyloid can harm your cells is by promoting the degradation of healthy proteins, such as proteins required for proper nerve functioning, explains a study in the "Journal of Neurochemistry" in 2000. This loss of important proteins within your cells ultimately causes cellular dysfunction and tissue damage, and the accumulation of amyloid protein can cause disease.
Implications in Alzheimer's Disease
Amyloid protein is closely linked to the development of Alzheimer's disease, or AD. Patients with AD experience cognitive decline, as well as mood and personality disturbances, as a result of cumulative nerve damage within the brain. One characteristic of AD is the development of plaques, made from aggregations of toxic amyloid-beta protein. These amyloid plaques cause nerve death within the brain, and can eventually lead to a complete loss of cognition and ultimately prove fatal.
Implications in Amyloidosis
Amyloid protein can also cause amyloidosis, a disease in which amyloid forms deposits in other organs throughout your body, such as your heart or kidneys. Amyloid plaques disrupt normal organ function by leading or organ stiffness, which can interfere with heart muscle contraction or the movement of blood through your kidneys. In addition, the protein is toxic to your liver, and amyloidosis can cause liver swelling. The symptoms of amyloidosis can vary based on the organs most affected by the amyloid deposition, but the disease can prove fatal.
References
- "Journal of Neurochemistry"; Prevention of Beta-Amyloid Neurotoxicity by Blockade of the Ubiquitin-Proteasome Proteolytic Pathway; Favlt et al.; 2000
- "Science"; The Amyloid Hypothesis of Alzheimer's Disease: Progress and Problems on the Road to Therapeutics; Hardy et al.; 2002
- MedlinePlus: Primary Amyloidosis
