Joining the interface: a site for Nmd3 association on 60S ribosome subunits

Association between NMD3 and symptoms of Parkinson's disease in Chinese patients

Background

Parkinson’s disease (PD) is a progressive neurodegenerative movement disorder that is characterized by motor symptoms such as tremor, rigidity, slowness of movement and problems with gait. Large-scale meta-analyses of genome-wide association studies (GWAS) have identified few susceptibility loci in patients with sporadic PD. The aim of this study was to investigate the association between NMD3 single nucleotide polymorphism (SNP) and symptoms in PD patients in South China.

Methods

A total of 217 PD patients were recruited in this study and genotyped by using the SNaPshot technique and the polymerase chain reaction. All subjects were evaluated by the Mini-Mental State Examination (MMSE), Beijing version Montreal Cognitive Assessment (MoCA), Sniffin’ Sticks 16 (SS-16), Hamilton Anxiety Rating Scale, Hamilton Depression Rating Scale, 39-item Parkinson’s Disease Questionnaire (PDQ-39) and MDS Unified PD Rating Scale (MDS-UPDRS).

Results

NMD3 rs34016896 (C > T) carriers have worse cognitive function than wild types (MMSE: p = 0.042, NMD3 wild type: 27.44 ± 2.89, NMD3 carriers: 26.31 ± 3.79; MoCA: p = 0.005, NMD3 wild type: 23.15 ± 4.20, NMD3 carriers: 20.75 ± 6.68).

Conclusions

The recessive and overdominant model of NMD3 rs34016896 was associated with cognitive impairment in PD patients.

Yeast ribosomal protein L40 assembles late into precursor 60 S ribosomes and is required for their cytoplasmic maturation

Most ribosomal proteins play important roles in ribosome biogenesis and function. Here, we have examined the contribution of the essential ribosomal protein L40 in these processes in the yeast Saccharomyces cerevisiae. Deletion of either the RPL40A or RPL40B gene and in vivo depletion of L40 impair 60 S ribosomal subunit biogenesis. Polysome profile analyses reveal the accumulation of half-mers and a moderate reduction in free 60 S ribosomal subunits. Pulse-chase, Northern blotting, and primer extension analyses in the L40-depleted strain clearly indicate that L40 is not strictly required for the precursor rRNA (pre-rRNA) processing reactions but contributes to optimal 27 SB pre-rRNA maturation. Moreover, depletion of L40 hinders the nucleo-cytoplasmic export of pre-60 S ribosomal particles. Importantly, all these defects most likely appear as the direct consequence of impaired Nmd3 and Rlp24 release from cytoplasmic pre-60 S ribosomal subunits and their inefficient recycling back into the nucle(ol)us. In agreement, we show that hemagglutinin epitope-tagged L40A assembles in the cytoplasm into almost mature pre-60 S ribosomal particles. Finally, we have identified that the hemagglutinin epitope-tagged L40A confers resistance to sordarin, a translation inhibitor that impairs the function of eukaryotic elongation factor 2, whereas the rpl40a and rpl40b null mutants are hypersensitive to this antibiotic. We conclude that L40 is assembled at a very late stage into pre-60 S ribosomal subunits and that its incorporation into 60 S ribosomal subunits is a prerequisite for subunit joining and may ensure proper functioning of the translocation process.