Amino Acids in Autophagy: Regulation and Function.

Autophagy is a dynamic process in which the eukaryotic cells break down intracellular components by lysosomal degradation. Under the normal condition, the basal level of autophagy removes damaged organelles, misfolded proteins, or protein aggregates to keep cells in a homeostatic condition. Deprivation of nutrients (e.g., removal of amino acids) stimulates autophagy activity, promoting lysosomal degradation and the recycling of cellular components for cell survival. Importantly, insulin and amino acids are two main inhibitors of autophagy. They both activate the mTOR complex 1 (mTORC1) signaling pathway to inhibit the autophagy upstream of the uncoordinated-51 like kinase 1/2 (ULK1/2) complex that triggers autophagosome formation. In particular, insulin activates mTORC1 via the PI3K class I-AKT pathway; while amino acids activate mTORC1 either through the PI3K class III (hVps34) pathway or through a variety of amino acid sensors located in the cytosol or lysosomal membrane. These amino acid sensors control the translocation of mTORC1 from the cytosol to the lysosomal surface where mTORC1 is activated by Rheb GTPase, therefore regulating autophagy and the lysosomal protein degradation.

Therapeutic Potential of Phytochemicals in Combination with Drugs for Cardiovascular Disorders.

The incidence of cardiovascular disorders is increasing worldwide. Heart disease is the leading cause of death for both men and women. High blood pressure, high low-density lipoprotein cholesterol level, and smoking are key risk factors for heart disease. Other medical conditions such as diabetes, overweight, obesity and lifestyle can put people at a higher risk for coronary heart disease. The preventive measures based on the common drugs may help reduce the risk of cardiovascular diseases. The present review highlights the contributions of therapeutic potential of phytochemicals in management of cardiovascular diseases. However, the delivery efficiency of therapeutic agents can be enhanced in order to improve the efficacy of phytochemicals as a therapeutic agent. The oral administration of phytochemicals as therapeutic agents is a common approach. The review highlights the recent development of natural products for the complementary treatment of cardiovascular diseases. These findings indicate that the combination of therapeutic drugs and natural products may improve the treatment efficacy of therapeutic agents.