A quantitative analysis of extracellular matrix proteins in the developing murine heart
The extracellular matrix (ECM) of the embryonic heart has been implicated to play an essential role in key developmental processes. The ECM is a critical tissue component that provides structural support as well as important regulatory signaling cues to govern cellular growth, metabolism, and differentiation. To date however, the dynamic regulation of ECM proteins with cardiac development has not been described. Here we evaluate the composition of the ECM at key developmental time points corresponding to cardiomyocyte proliferation and differentiation. Samples were decellularized, digested, and purified before quantification via mass spectrometry. A tool to aid in analysis of mass spectroscopy raw data was developed to allow for accurate and rapid data processing. Using EmPAI values, relative concentrations of ECM components could be calculated. Results indicate an increase in elastin and matricellular proteins during this developmental window. In addition, several individual proteins, such as collagen IV and laminin, showed statistically significant changes over time. Thus, here we share a useful analysis regime for ECM proteomics and also set the stage to establish whether developmental changes impact on the composition of the ECM or whether instead changes in the ECM dictate developmental outcomes.