Mutant huntingtin stalls ribosomes and represses protein synthesis independent of fragile X mental retardation protein

ABSTRACT: Ribosomes translocate one codon at a time in mRNA during protein synthesis, but the regulators of ribosome translocation and their impact on neurodegenerative disease remain poorly understood. Here, we show that huntingtin (Htt) and its poly-Q expanded form, mHtt, a cause of Huntington disease (HD), promotes ribosome stalling and suppresses protein synthesis in vivo and in vitro. We found that fragile mental retardation protein (FMRP), a known promoter of ribosome stalling, is upregulated in HD cells and patients’ tissue. Unexpectedly, FMRP depletion fails to reverse mHtt-mediated ribosome stalling in HD cells. mHtt binds directly to ribosomes in a RNase-sensitive manner and interacts with ribosomal proteins. Combining high-resolution ribosome footprint profiling (Ribo-Seq) and RNA-Seq, we provide a global snapshot of stalling on mRNA transcripts, with a shift in ribosome occupancy toward the 5’ and 3’ end and single-codon unique pauses in HD cells. We also found ribosomes that appear to have stalled in mHtt mRNA before CAG repeat expansion. Thus, Htt regulates protein synthesis via ribosome stalling mechanisms and in turn may affect mRNA elongation, which may be exploited for HD therapeutics.

INSTRUMENT(S): Orbitrap Fusion

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Fibroblast Cell Line, Fibroblast

DISEASE(S): Huntington Disease

SUBMITTER: gogce crynen  

LAB HEAD: Srinivasa Subramaniam

PROVIDER: PXD017115 | Pride | 2021-04-06

REPOSITORIES: Pride