Regulation of aberrant translation initiation at atypical start codons.

Canonical eukaryotic translation initiation utilizes the universal AUG start codon. However, it’s been known for decades that codons that differ by a single nucleotide (e.g., CUG, GUG, AUU) can be weakly used to initiate translation (termed non-AUG translation). Multiple human neurological disorders and cancers are now known to be directly linked to increased non-AUG translation due to the resulting production of neurotoxic homopolymeric proteins and specific oncoproteins, respectively. We aim to use biochemical and molecular biology approaches to better understand how non-AUG translation is regulated, including by alternative initiation factors. Additionally, we identified a set of small molecules that selectively modulate non-AUG translation in human cells, allowing for a novel tool to elucidate unique regulatory pathways that potentially can be targeted for therapeutic development.

Translational control by RNA-binding proteins & ribosome-associated proteins.

Translation is controlled at all four major steps: initiation, elongation, termination, and subunit recycling. Such regulation can be stimulated by multiple internal and external ques (e.g., cell stress), as well as by cellular factors that bind to the ribosome (e.g., initiation and elongation factors) and mRNAs. Not surprisingly, multiple human disease are linked to many of these translational control steps. For example, the loss of the ribosome-binding elongation inhibitor FMRP causes Fragile X Syndrome, the leading single gene cause of autism and intellectual disability. We are currently employing a new strategy (that does not require genome editing that current strategies rely on) to identify novel ribosome-associated proteins in multiple tissue- and cells-types. We are interested in how such proteins regulate translation and ribosome dynamics, how they physically associate with or bind to ribosomes, and if any enzymatic capabilities they may possess are required to control translation.

Human diseases linked to the translation machinery.

Protein synthesis is essential in all cells. As such, nearly all of the components of the translation machinery are ubiquitously expressed. However, it is quite clear that mutations in many initiation factors and ribosomal proteins produce drastic tissue- and cell type-specific phenotypes and diseases. For example, mutations in all five subunits of the initiation factor eIF2B are linked to Vanishing White Matter disease, which most notably results in the detrimental loss of the myelin-sheath of neurons. eIF2B is the ubiquitously expressed guanine nucleotide exchange factor required to replenish active translation initiation complexes in all cells. However, it remains enigmatic how eIF2B mutations produce such a dramatic tissue-specific disease. A long term focus of the lab is to use a multi-pronged approach, including ribosome profiling and genome editing, to determine how mutations in the translation machinery affect the translation of cell type-specific mRNAs.

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