Distinct domains in the matricellular protein Lonely heart are crucial for cardiac extracellular matrix formation and heart function in Drosophila

• Published in: The Journal of biological chemistry 2018-05, Vol.293 (20), p.7864-7879
• Main Authors: Rotstein, Barbara, Post, Yanina, Reinhardt, Marcel, Lammers, Kay, Buhr, Annika, Heinisch, Jürgen J., Meyer, Heiko, Paululat, Achim
• Format: Article
• Language: English
• Subjects: ADAM Proteins - genetics; ADAM Proteins - metabolism; ADAMTS; ADAMTSL; Animals; Baculoviridae - genetics; Baculoviridae - metabolism; cardiac development; cardiac matrix; cardiogenesis; Cell Biology; Cloning, Molecular; Collagen Type IV - genetics; Collagen Type IV - metabolism; Drosophila; Drosophila genetics; Drosophila melanogaster; Drosophila melanogaster - genetics; Drosophila melanogaster - growth & development; Drosophila melanogaster - metabolism; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; Escherichia coli - genetics; Escherichia coli - metabolism; extracellular matrix; Extracellular Matrix - chemistry; Extracellular Matrix - metabolism; extracellular matrix protein; GAG; Gene Expression; Gene Expression Regulation, Developmental; Genetic Vectors - chemistry; Genetic Vectors - metabolism; Heart - growth & development; Heart - physiology; Organogenesis - genetics; Protein Domains; Protein Transport; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Repetitive Sequences, Amino Acid; Sf9 Cells; Signal Transduction; Spodoptera - cytology; Spodoptera - metabolism; thrombospondin; Thrombospondins - genetics; Thrombospondins - metabolism; TSR repeats
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M117.817940

The biomechanical properties of extracellular matrices (ECMs) are critical to many biological processes, including cell–cell communication and cell migration and function. The correct balance between stiffness and elasticity is essential to the function of numerous tissues, including blood vessels and the lymphatic system, and depends on ECM constituents (the “matrisome”) and on their level of interconnection. However, despite its physiological relevance, the matrisome composition and organization remain poorly understood. Previously, we reported that the ADAMTS-like protein Lonely heart (Loh) is critical for recruiting the type IV collagen–like protein Pericardin to the cardiac ECM. Here, we utilized Drosophila as a simple and genetically amenable invertebrate model for studying Loh-mediated recruitment of tissue-specific ECM components such as Pericardin to the ECM. We focused on the functional relevance of distinct Loh domains to protein localization and Pericardin recruitment. Analysis of Loh deletion constructs revealed that one thrombospondin type 1 repeat (TSR1-1), which has an embedded WXXW motif, is critical for anchoring Loh to the ECM. Two other thrombospondin repeats, TSR1-2 and TSR1-4, the latter containing a CXXTCXXG motif, appeared to be dispensable for tethering Loh to the ECM but were crucial for proper interaction with and recruitment of Pericardin. Moreover, our results also suggested that Pericardin in the cardiac ECM primarily ensures the structural integrity of the heart, rather than increasing tissue flexibility. In conclusion, our work provides new insights into the roles of thrombospondin type 1 repeats and advances our understanding of cardiac ECM assembly and function.