Functional investigations of DUF1220 protein domains.

摘要

Copy number expansion of genetic content is a powerful way in which species adapt to environments, and a powerful mechanism by which novel genes are generated. DUF1220 domains were previously identified as showing the largest human lineage-specific increase in copy number of any protein coding sequence with the human genome. While the function of DUF1220 domains remains obscure, the Sikela lab has identified a strong correlation between increasing DUF1220 copy number and increases in both brain size and cortical neuron number within great apes. In addition, a significant association has been reported between reduction and gain of DUF1220 copy number and brain size in microcephaly and macrocephaly, respectively . This thesis investigates the function of DUF1220 domains by further investigating the correlation between DUF1220 copy number and several physical brain measurements within anthropoid primates (monkey, ape and human). The spatiotemporal expression pattern in human fetal brain tissue was then evaluated, and suggested a role in neural progenitor expansion. In vitro cell culture experiments were then used to demonstrate the ability of DUF1220 to promote proliferation of human neural stem cells. Transcriptomics and proteomics studies both suggested a role in down regulating mitochondrial function, and this result was confirmed by live cell imaging using a mitochondrial dye. Finally, a functional evaluation of mitochondrial output in DUF1220 over expressing cells was performed, and found to slightly reduce metabolic output. I offer potential explanations linking the ability of DUF1220 to promote proliferation with the apparent reduction in mitochondrial output.