Growth Factors

VEGF proteins are crucial signaling molecules involved in vasculogenesis (the formation of the embryonic circulatory system) and angiogenesis (the growth of blood vessels from pre-existing vasculature) . They are expressed in various tissues, particularly in vascularized tissues . VEGF is also involved in the formation of new blood vessels during embryonic development, after injury, and in muscles following exercise . The expression of VEGF is regulated by factors such as oxygen tension, cytokines, and differentiation .

The primary function of VEGF is to promote the growth of new blood vessels. It plays a critical role in embryonic development, wound healing, and the formation of collateral circulation to bypass blocked vessels . VEGF is also involved in immune responses by being chemotactic for granulocytes and macrophages . It contributes to pathological conditions such as tumor growth and metastasis, as well as vascular diseases in the retina .

VEGF exerts its effects by binding to tyrosine kinase receptors (VEGFRs) on the cell surface, leading to receptor dimerization and activation through transphosphorylation . The primary receptors for VEGF are VEGFR-1 (Flt-1) and VEGFR-2 (KDR/Flk-1) . These receptors activate downstream signaling cascades that promote endothelial cell proliferation, migration, and survival . VEGF also interacts with co-receptors such as neuropilins, which modulate its activity .

The expression and activity of VEGF are tightly regulated at multiple levels. Transcriptional regulation is influenced by oxygen levels, with hypoxia being a major inducer of VEGF gene transcription . Other regulatory factors include growth factors, hormones, and oncogenes . Post-translational modifications, such as phosphorylation, also play a role in modulating VEGF activity . Additionally, VEGF signaling is regulated by the availability of its receptors and the presence of co-receptors .

VEGF has significant applications in biomedical research, diagnostics, and therapeutics. In research, recombinant VEGF proteins are used to study angiogenesis and related signaling pathways . Clinically, VEGF inhibitors such as bevacizumab (Avastin) are used to treat cancers by inhibiting tumor angiogenesis . VEGF is also targeted in therapies for age-related macular degeneration and diabetic retinopathy . Diagnostic tools measuring VEGF levels can help in assessing disease progression and treatment efficacy .

VEGF plays a vital role throughout the life cycle, from development to aging and disease. During embryogenesis, VEGF is essential for the formation of the vascular system . In adults, it is involved in physiological processes such as wound healing, menstrual cycles, and pregnancy . VEGF also contributes to pathological conditions, including cancer, retinopathy, and inflammatory diseases . Its role in promoting angiogenesis makes it a critical factor in both normal physiology and disease states .