PROJECT SUMMARY One of the most surprising discoveries from the Human Genome Project is that only about 1.5% of the genome codes for proteins, whereas around 46% comprises transposable elements (TEs). Functional assessment of how these ubiquitous TEs affect human development and health has posed a major challenge. While most TEs are considered non-functional, or “junk” DNA, here I argue that TE-induced gene regulation is strongly underestimated due to the historical tendency to explore TE functionality by studying individual TEs independently of each other. I propose to provide a novel framework to study how interactions between the hitherto “junk” TE sequences can regulate pre-mRNA splicing to affect gene function, and investigate whether such a mechanism could substantially affect both human development and evolution, and help explain the genetic etiology of human diseases. This proposal is inspired from my recent discovery that the interaction between a pair of Alu retrotransposons may explain the long-sought genetic basis for the evolution of tail loss in human and apes. Based on this work and my preliminary data, I will first use the Alu pair interaction in TBXT gene as a model to demonstrate that the interaction between intronic TEs can profoundly impact human development and health, and explain the etiology of a common genetic disease (Aim 1). Aim 2 proposes to test the hypothesis that the isoform of TBXT induced by interaction of the Alu pair pleiotropically contributes to strengthening of hindlimbs, thus directly testing the long-standing hypothesis that the tail-loss evolution in hominoids is associated with bipedal locomotion evolution (Aim 2). Beyond the specific interaction of the Alu pair in the TBXT gene, Aim 3 will develop an algorithm called TEILO (Transposable Element Interaction & Local Organization) to systematically identify the functional TE interactions that affect gene function and human health by modulating alternative splicing. This work promises to provide a new paradigm to studying the interaction between TEs and its implication to human health and diseases.

PROJECT NARRATIVE Functional assessment of how the ubiquitous transposable elements (TEs) affect human development and health has posed a major challenge. This proposal aims to provide a novel framework to study how interactions between the hitherto “junk” TE sequences can regulate pre-mRNA splicing to affect gene function, and argues that such a mechanism can substantially affect both human development and evolution, and help explain the genetic etiology of human diseases.