TGF beta 1

Protein coding gene in the species Homo sapiens

Transforming growth factor beta 1 or TGF β1 is a polypeptide member of the transforming growth factor beta superfamily of cytokines. It is a secreted protein that performs many cellular functions, including the control of cell growth, cell proliferation, cell differentiation, and apoptosis. In humans, TGF β1 is encoded by the gene.

TGF β is a multifunctional set of peptides that controls proliferation, differentiation, and other functions in many cell types. TGF β acts synergistically with transforming growth factor alpha (TGF α) in inducing transformation. It also acts as a negative autocrine growth factor. Dysregulation of TGF β activation and signaling may result in apoptosis. Many cells synthesize TGF β and almost all of them have specific receptors for this peptide. TGF β1, TGF β2, and TGF β3 all function through the same receptor signaling systems. TGF β1 was first identified in human platelets as a protein with a molecular mass of 25 kilodaltons with a potential role in wound healing. It was later characterized as a large protein precursor (containing 390 amino acids) that was proteolytically processed to produce a mature peptide of 112 amino acids. TGF β1 plays an important role in controlling the immune system, and shows different activities on different types of cell, or cells at different developmental stages. Most immune cells (or leukocytes) secrete TGF β1.

Some T cells (e. g. regulatory T cells) release TGF β1 to inhibit the actions of other T cells. Specifically, TGF β1 prevents the interleukin(IL) 1 & interleukin 2 dependent proliferation in activated T cells, as well as the activation of quiescent helper T cells and cytotoxic T cells. Similarly, TGF β1 can inhibit the secretion and activity of many other cytokines including interferon γ, tumor necrosis factor alpha (TNF α), and various interleukins. It can also decrease the expression levels of cytokine receptors, such as the IL 2 receptor to down regulate the activity of immune cells. However, TGF β1 can also increase the expression of certain cytokines in T cells and promote their proliferation, particularly if the cells are immature. and controls the expression of antibody, transferrin and MHC class II proteins on immature and mature B cells.