CD157, also known as bone marrow stromal cell antigen 1 (BST1), is a glycosylphosphatidylinositol (GPI)-anchored glycoprotein with a dual function as a receptor and a β-NAD+-metabolizing ectoenzyme of the ADP-ribosyl cyclases gene family¹.

CD157 and its paralog CD38, catalyze the formation of cyclic ADP-ribose (cADPR) from NAD, a second messenger involved in intracellular calcium mobilization through ryanodine receptors, among other functions ^1,2.

As a receptor, CD157 interacts with β1 and β2 integrins (CD29 and CD18 respectively) to form a multimolecular complex that mediates intracellular signaling through the FAK/Src pathway ^1-3. Known ligands for CD157 include extracellular matrix components like fibronectin, fibrinogen, laminin-1 and type 1 collagen ^2,3.

As it name suggests, CD157 was first identified in bone marrow-derived cells, but it is also expressed in other immune system cells like neutrophils, T-cells, pre B-cells and macrophages. CD157 has been demonstrated to be involved in both the innate and adaptive immune response with roles in B- and T-cell growth and the control of myeloid cells migration during inflammation ¹.

CD157 is considered a marker and therapeutic target for several hematological malignancies like acute myeloid leukemia (AML) as well as several solid tumors like ovarian and malignant mesothelioma ^3,4,5.

Outside the immune system, CD157 is expressed in vascular endothelium, intestine and brain among others. Interestingly, CD157, has been identified as a risk factor for neurodegenerative diseases, particularly Parkinson's disease ^2,6. The exact role of CD157 in the nervous system is not clear, but it appears to have a role in neurogenesis and neural stem cells proliferation, as well as a role in neuroinflammation probably through its association with CD18 and CD11b ^2,7.

Finally, studies with CD157 knockout mice, reveal its involvement in depression-like behaviors, social avoidance and anxiety disorders ^2,8.