The Beclin 1 protein is a central regulator of autophagy in mammalian cells.
Autophagy is an essential process used to maintain cellular homeostasis by degrading and recycling cellular components such as damaged or worn out organelles and macromolecules.
Autophagy is also activated in response to cellular stresses such as nutrient starvation or intracellular pathogens and can protect the cell from programmed cell death.
Beclin 1 acts during the initiation*** stage of autophagy by forming the isolation membrane, a double-membrane structure that engulfs cytoplasmic material to form the autophagosome.
Under normal conditions the anti-apoptotic protein Bcl-2 inhibits autophagy by interacting with Beclin 1 through its BH-3 only domain.
Beclin 1 is also an important tumor suppressor whose expression is reduced in many cancer types including breast**, ovarian**, and prostate**.
The reduced levels of Beclin 1 are thought to inhibit autophagy and prevent the turnover of damaged mitochondria which leads to production of reactive oxygen species** and genotoxic stress**.