Talk abstracts
Talk on Friday 04:00-04:15pm submitted by Misbah Khan
PUMILIO post-transcriptional regulation of nuclear encoded mitochondrial genes in human cells.
Misbah Khan (The Ohio State University), Ronghao Chen (The Ohio State University), Swetha Rajasakaran (The Ohio State University), Jalal Siddiqui (The Ohio State University), Ganesh Koshre,Rebecca Lisi (The Ohio State University), Wayne Miles (The Ohio State University)
Abstract:
Mitochondria are important energy generating organelles within the cell. Although Mitochondria do contain a small genome, the vast majority of (>95%) proteins that function within the Mitochondria are nuclear encoded (Nuclear Encoded Mitochondrial Genes, NEMG). Mitochondria are specialized environments that enable metabolic enzymatic reactions to occur for efficient energy and macromolecule production. To facilitate this, the pH of the mitochondria is different from the cytoplasm, requiring many of the proteins that fuel mitochondrial activity to be synthesized into protein, either on the surface or inside the mitochondrial to be functional. This requires: 1) the RNA to be transported to the mitochondria AND 2) not to be translated into protein until it completes its journey across the cytoplasm. Errors in this process, diminish mitochondria output and organismal fitness. The PUMILIO family of RNA binding proteins is evolutionarily conserved and bind to defined RNA sequences within the 3’UTR of their substrates. In human cells, PUM1 and PUM2 bind to UGUAHAUA motifs. While profiling PUM1-/-, PUM2-/- and PUM1/2-/- human cells, we found widespread alterations in metabolic and mitochondrial function. Using eCLIP, Ribosome profiling and RNA-sequencing, we identified around 25% of all NEMGs are PUM substrates in human cells and loss of PUM regulation resulted in increased Ribosome occupancy. These RNAs were still mostly localized to the mitochondria correctly. To determine how NEMG that are PUM substrates are transported, we computational mapped motifs and identified a recurrent structures in NEMG vs. non-NEMG PUM substrates. Using this structure as bait, we found LRRPRC binds and in cooperation with PUM, facilitates NEMG RNA transport.
Keywords: PUMILIO, Nuclear Encoded Mitochondrial Genes