Endoplasmic reticulum stress and angiogenesis

The endoplasmic reticulum is a dynamic intracellular organelle with exquisite sensitivity to alterations in homeostasis, and provides stringent quality control systems to ensure that the only correctly folded proteins transit to the Golgi and unfolded or misfolded proteins are retained and ultimately degraded. The endoplasmic reticulum stress represents the unfolded protein response to cope with the accumulation of unfolded or misfolded proteins and is required to maintain the functional integrity of the endoplasmic reticulum. The endoplasmic reticulum stress is a fundamental phenomenon which provides a secure protection of the cells from different factors. This stress provides a wide spectrum of physiological roles in diverse developmental and metabolic processes, especially for professional secretory cells with high-level secretory protein synthesis, such as pancreatic beta cells, hepatocytes and osteoblasts and is required throughout the entire life. The endoplasmic reticulum stress and hypoxia are the obligate components of malignant tumor growth, are interconnected and activate angiogenesis via growth and metabolism control. The endoplasmic reticulum stress is mediated by three by three sensor and signaling pathways (PERK, ATF6 and ERN1), besides that blockade one (ERN1) leads to a decrease of tumor growth through suppression of angiogenesis and proliferation. The data concerning the interaction of signaling enzyme ERN1 and pro- and anti-angiogenic gene expressions is analyzed.