Characterization of the zebrafish family of Trak proteins

Mitochondria serve as the site of oxidative phosphorylation and can move to areas that possess high energetic needs within a cell.  This movement is necessary to maintain basic metabolic functions, and disruption of this motility often results in cell death.

Zebrafish-Mitochondria

Kelsey Oonk (L) and Courtney Reddig 

Faculty Sponsor:
Dr. Susan Walsh

In fruit flies and mammals, Miro, an outer mitochondrial membrane protein, and Trak, a kinesin adaptor protein, comprise one protein complex that regulates mitochondrial trafficking along microtubules.  Our research aims to determine the role of the zebrafish Trak family of proteins.  Through sequence homology, we have identified three zebrafish Trak proteins:  zTrak1, zTrak2, and zTrak1-like. When expressed in COS7 cells, both human Trak1 and Trak2 are mitochondrial. However, in COS7 cells, zTrak1 does not localize to the mitochondria, yet zTrak2 does. A chimeric protein containing the N-terminus of zTrak1 and the C-terminus of human Trak1 relocated to the mitochondria, indicating that the C-terminus of hTrak1 is sufficient to direct mitochondrial localization, and the C-terminus of zTrak1 is likely responsible for its cytosolic localization. Given the low amino acid conservation among these paralogs, these zebrafish proteins might have different cellular functions, and we are currently exploring the role of these proteins in vivo using antisense morpholino oligonucleotides and RNA in situ hybridization in developing zebrafish embryos. Taken altogether, this research will lay the foundation for studies in the role of mitochondrial motility during vertebrate development.