Neuromuscular Regulation of Bone in the Zebrafish Skeleton
Large-scale biological approaches such as forward screens and systems biology-based investigations are recognized to be vital for the advancement of biomedical research. Zebrafish (a small tropical freshwater fish that has gained prominence for its use in developmental biology) are ideal for such approaches due to their unique attributes such as optical transparency, ease of genetic manipulation, small size, and low cost. We are currently developing new bone phenotyping technologies and models of neuromuscular-mediated bone pathologies in zebrafish to enable systems-based investigations of nerve, muscle, and bone interactions. An example can be seen in the above schematic, which demonstrates the generation of a musculoskeletal “barcode” containing 576 different descriptors of axial muscle and bone morphology for a single zebrafish. The barcode was computed using a rapid MicroCT-based phenotyping platform which we developed. Such barcodes can be used to identify emergent or coordinated behaviors between many different muscles and bones in normal and pathological conditions.
Bone Systems Biology in the Regenerating Zebrafish Fin
Of the bony structures in zebrafish, the regenerating fin provides a compelling system for enabling systems-based investigations of bone growth. Following fin amputation, osteoblasts at the stump de-differentiate to form a proliferative mass of cells called the blastema, and then re-differentiate to undergo bone formation. The rate of bone growth during this process is remarkable, as new bone segments are readily observed within 3–5 days following amputation (with the majority of lost bone, joints, nerves, skin and blood vessels restored within a few weeks). Interestingly, a growing body of evidence indicates that the major phases of mammalian osteoblastic differentiation are recapitulated during bone regeneration in the fin. We are currently integrating novel bone phenotyping technologies and exploiting the amenability of zebrafish to genetic manipulation and high-throughput approaches to pursue large-scale, systems-based investigations of bone formation and mineralization in the regenerating fin.
In recent years, mechanical signals have become widely recognized as being critical to the proper functioning of numerous biological processes. This has led to the emergence of a new discipline, cellular mechanobiology, which bridges cell biology with various disciplines of mechanics and which seeks to uncover the principles by which the sensation or generation of mechanical force regulates cell function. A second component of our research focuses on investigating mechanobiological processes using systems biology-based approaches. An example of this can be seen in the above image, which depicts results from a genome-wide gene expression screen for genes that are differentially regulated by continuous and intermittent mechanical stimulation. We are currently developing novel mechanotransdution assays that will enable large-scale (1000s of samples per day) assessments of mechanosensory function. By integrating these assays with available technologies for high-throughput screening, we seek to enable, for the first time, large-scale chemical and genetic screens for the discovery of novel mediators of cellular mechanotransduction. In addition, using a combination of genome-wide expression analyses and bioinformatics, we are developing novel approaches for de novo discovery of signaling mechanisms mediating cellular mechanotransduction.