The P387 thrombospondin-4 variant promotes accumulation of macrophages in atherosclerotic lesions

Thrombospondins: Conserved mediators and modulators of metazoan extracellular matrix

This review provides a personal overview of significant scientific developments in the thrombospondin field during the course of my career. Thrombospondins are multidomain, multimeric, calcium-binding extracellular glycoproteins with context-specific roles in tissue organisation. They act at cell surfaces and within ECM to regulate cell phenotype and signalling, differentiation and assembly of collagenous ECM, along with tissue-specific roles in cartilage, angiogenesis and synaptic function. More recently, intracellular, homeostatic roles have also been identified. Resolution of structures for the major domains of mammalian thrombospondins has facilitated major advances in understanding thrombospondin biology from molecule to tissue; for example, in illuminating molecular consequences of disease-causing coding mutations in human pseudoachrondroplasia. Although principally studied in vertebrates, thrombospondins are amongst the most ancient of animal ECM proteins, with many invertebrates encoding a single thrombospondin and the thrombospondin gene family of vertebrates originating through gene duplications. Moreover, thrombospondins form one branch of a thrombospondin superfamily that debuted at the origin of metazoans. The super-family includes additional sub-groups, present only in invertebrates, that differ in N-terminal domain organisation, share the distinctive TSP C-terminal region domain architecture and, to the limited extent studied to date, apparently contribute to tissue development and organisation. Finally, major lines of translational research are discussed, related to fibrosis; TSP1, TSP2 and inhibition of angiogenesis; and the alleviation of chronic cartilage tissue pathologies in pseudoachrondroplasia.

In the balance: how do thrombospondins contribute to the cellular pathophysiology of cardiovascular disease?

Thrombospondins (TSPs) are multidomain, secreted proteins that associate with cell surfaces and extracellular matrix. In mammals, there is a large body of data on functional roles of various TSP family members in cardiovascular disease (CVD), including stroke, cardiac remodeling and fibrosis, atherosclerosis, and aortic aneurysms. Coding single nucleotide polymorphisms (SNPs) of TSP1 or TSP4 are also associated with increased risk of several forms of CVD. Whereas interactions and functional effects of TSPs on a variety of cell types have been studied extensively, the molecular and cellular basis for the differential effects of the SNPs remains under investigation. Here, we provide an integrative review on TSPs, their roles in CVD and cardiovascular cell physiology, and known properties and mechanisms of TSP SNPs relevant to CVD. In considering recent expansions to knowledge of the fundamental cellular roles and mechanisms of TSPs, as well as the effects of wild-type and variant TSPs on cells of the cardiovascular system, we aim to highlight knowledge gaps and areas for future research or of translational potential.