Harvard Catalyst Profiles

Tim Hla's laboratory has been investigating the role of lipid mediators, sphingosine 1-phosphate (S1P) and prostanoids in vascular biology and disease. In the 1990s, we cloned the inducible cyclooxygenase (COX-2) and the first S1P receptor. Our work defined how the COX-2 pathway regulates angiogenesis, cancer and inflammatory disease. Recently, we are examining molecular mechanisms by which prostanoids interact with other lipid signaling systems to protect the vascular system and maintain health. Secondly, since our discovery of the S1P receptor, we have been working on how this novel signaling pathway regulates vascular development, homeostasis and is dysregulated in vascular diseases. In addition, our work contributed to the development of S1P receptor inhibitors, which are being used for the treatment of a number of autoimmune diseases. Recently, we discovered that HDL-bound S1P activates vascular S1P receptors to inhibit vascular injury and disease. We also showed that proteins that bind to S1P, such as the HDL-bound apolipoprotein M (ApoM), direct specific biological functions of S1P by activating S1P receptors in unique ways. This mode of signaling, termed as, chaperone-dependent S1P signaling, may be a general mechanism for lipid mediators that are poorly soluble in water. We are also examining novel mechanisms of S1P metabolism, export into the extracellular environment, capture and signaling by novel chaperones, receptor-dependent signaling mechanisms and cross-talk with other cytokine, growth factor signaling pathways. Such mechanistic information is useful not only to achieve a deeper understanding of vascular health and disease but also to develop new therapeutic entities. In fact, our laboratory is developing novel small molecules as well as protein biotherapeutics to modulate heart disease, stroke, autoimmune diseases, eye disease and cancer.