CD109

CD109 is a glycosylphosphatidylinositol (GPI)-anchored glycoprotein that is a member of the α2-macroglobulin/C3, C4, C5 family of thioester-containing proteins. It is expressed on the surface of various cell types, including platelets, activated T-cells, and certain cancer cells. CD109 is involved in the regulation of transforming growth factor beta (TGF-β) signaling, which plays a crucial role in cell proliferation, differentiation, and immune responses.

Structure and Function

CD109 is a large glycoprotein with a molecular weight of approximately 170 kDa. It is anchored to the cell membrane via a GPI anchor, which allows it to be released from the cell surface by phospholipase enzymes. The protein contains several domains, including a thioester bond that is characteristic of the α2-macroglobulin family.

CD109 modulates TGF-β signaling by binding to TGF-β receptors and inhibiting their activity. This interaction can lead to the downregulation of TGF-β-mediated cellular responses, which is important in controlling cell growth and immune function. Dysregulation of CD109 expression or function has been implicated in various pathological conditions, including cancer and fibrosis.

Expression and Clinical Significance

CD109 is expressed in a variety of tissues, with high levels found in the skin, lung, and liver. It is also present on the surface of platelets and activated T-cells. In the context of cancer, CD109 expression has been observed in squamous cell carcinoma, melanoma, and other tumor types. Its role in cancer is complex, as it can both promote and inhibit tumor progression depending on the context.

In addition to its role in cancer, CD109 has been studied in the context of autoimmune diseases and fibrotic disorders. Its ability to modulate TGF-β signaling makes it a potential therapeutic target for conditions characterized by excessive fibrosis or immune dysregulation.

Research and Therapeutic Potential

Research on CD109 is ongoing, with studies focusing on its role in cancer biology, immune regulation, and tissue repair. The development of CD109-targeted therapies is an area of interest, particularly for diseases where TGF-β signaling is dysregulated. Potential therapeutic strategies include the use of antibodies or small molecules to modulate CD109 activity or expression.

Also see

• Transforming growth factor beta
• Glycosylphosphatidylinositol
• Thioester-containing proteins
• Cancer biology
• Immune regulation

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