Mild Parkinsonian Signs in a Community Ambulant Population.

BACKGROUND: Mild parkinsonian signs (MPS) are common in the older adult and associated with a wide range of adverse health outcomes. There is limited data on the prevalence of MPS and its significance. OBJECTIVE: To determine the prevalence of MPS in the community ambulant population and to evaluate the relationship of MPS with prodromal features of Parkinson's disease (PD) and cognition. METHODS: This cross-sectional community-based study involved participants aged ≥50 years. Parkinsonian signs were assessed using the modified Unified Parkinson's Disease Rating Scale (mUPDRS) and cognition using the Montreal Cognitive Assessment (MoCA). Premotor symptoms of PD were screened using a self-reported questionnaire. Linear regression was used to assess the association of MPS with premotor symptoms of PD and cognitive impairment. RESULTS: Of 392 eligible participants, MPS was present in 105 (26.8%). Mean age of participants with MPS was 68.8±6.9 years and without MPS was 66.1±5.9 years (p < 0.001). Multivariate analysis revealed that MoCA scores were significantly lower in the MPS group (ß= -0.152, 95% CI = -0.009, -0.138, p < 0.05). A significant correlation between the presence of REM sleep behavior disorder (RBD) and total MPS scores (ß= 0.107, 95% CI = 0.053, 1.490, p < 0.05) was also found. Neither vascular risk factors nor other premotor symptoms were significantly associated with MPS. CONCLUSION: MPS is common and closely related to cognitive impairment and increasing age. Presence of RBD is predictive of higher MPS scores. This study highlights the necessity of other investigations or sensitive risk markers to identify subjects at future risk of PD.

Structural connectome alterations in prodromal and de novo Parkinson's disease patients.

BACKGROUND: Although the clinical signs of prodromal Parkinson's disease (PD) have been identified, little is known about the neural features of the prodromal phase of PD (proPD). The aim of this study was to examine the structural network alterations from healthy aging to proPD and to early PD. METHODS: 181 non-demented and non-depressed participants comprising 55 healthy controls (HCs), 20 proPDs, and 106 de novo PD patients (dPDs) were included in the study and underwent clinical assessment and diffusion tensor imaging scanning. Graph-theoretical analysis and network-based statistics, with age and gender as nuisance covariates, were used. RESULTS: Compared with HCs and dPDs, proPD patients showed significantly elevated small-worldness and clustering coefficient (Ps < 0.01) and greater local connectivity between regions relating to motor, olfactory and sleep functions (Ps < 0.05). Although dPDs and HCs did not differ on all graph-theoretic metrics, dPD patients showed decreased connectivity within the prefrontal regions and between the left temporal and occipital lobes (P < 0.05). The connectivity strength between these regions significantly distinguished between diagnostic groups. Connectivity between bilateral SMAs was correlated with UPSIT in HCs and with UPDRS-III in dPDs. Connectivity between the right SMA and putamen was correlated RBDSQ in proPDs. CONCLUSIONS: Increased network efficiency and connectivity of proPDs and decreased local connectivity of dPDs might suggest the emergence and dissipation of neural compensation in the prodromal phase and in early PD, respectively. Nonetheless, longitudinal studies are needed to follow up the long-term structural network changes of proPD patients.

BORC Regulates the Axonal Transport of Synaptic Vesicle Precursors by Activating ARL-8.

Axonal transport of synaptic vesicle precursors (SVPs) is essential for synapse development and function. The conserved ARF-like small GTPase ARL-8 is localized to SVPs and directly activates UNC-104/KIF1A, the axonal-transport kinesin for SVPs in C. elegans. It is not clear how ARL-8 is activated in this process. Here we show that part of the BLOC-1-related complex (BORC), previously shown to regulate lysosomal transport, is required to recruit and activate ARL-8 on SVPs. We found mutations in six BORC subunits-blos-1/BLOS1, blos-2/BLOS2, snpn-1/Snapin, sam-4/Myrlysin, blos-7/Lyspersin, and blos-9/MEF2BNB-cause defects in axonal transport of SVPs, leading to ectopic accumulation of synaptic vesicles in the proximal axon. This phenotype is suppressed by constitutively active arl-8 or unc-104 mutants. Furthermore, SAM-4/Myrlysin, a subunit of BORC, promotes the GDP-to-GTP exchange of ARL-8 in vitro and recruits ARL-8 onto SVPs in vivo. Thus, BORC regulates the axonal transport of synaptic materials and synapse formation by controlling the nucleotide state of ARL-8. Interestingly, the other two subunits of BORC essential for lysosomal transport, kxd-1/KXD1 and blos-8/Diaskedin, are not required for the SVP transport, suggesting distinct subunit requirements for lysosomal and SVP trafficking.

The intraflagellar transport protein IFT27 promotes BBSome exit from cilia through the GTPase ARL6/BBS3.

The sorting of signaling receptors into and out of cilia relies on the BBSome, a complex of Bardet-Biedl syndrome (BBS) proteins, and on the intraflagellar transport (IFT) machinery. GTP loading onto the Arf-like GTPase ARL6/BBS3 drives assembly of a membrane-apposed BBSome coat that promotes cargo entry into cilia, yet how and where ARL6 is activated remains elusive. Here, we show that the Rab-like GTPase IFT27/RABL4, a known component of IFT complex B, promotes the exit of BBSome and associated cargoes from cilia. Unbiased proteomics and biochemical reconstitution assays show that, upon disengagement from the rest of IFT-B, IFT27 directly interacts with the nucleotide-free form of ARL6. Furthermore, IFT27 prevents aggregation of nucleotide-free ARL6 in solution. Thus, we propose that IFT27 separates from IFT-B inside cilia to promote ARL6 activation, BBSome coat assembly, and subsequent ciliary exit, mirroring the process by which BBSome mediates cargo entry into cilia.

The ecdysone receptor (ScEcR-A) binds DNA puffs at the start of DNA amplification in Sciara coprophila.

The steroid hormone ecdysone induces DNA amplification and subsequent DNA puff formation in late fourth larval instar salivary gland polytene chromosomes of the fungus fly, Sciara coprophila. Previous in vitro studies on DNA puff II/9A in Sciara demonstrated that the ecdysone receptor (ScEcR-A) efficiently binds an ecdysone response element adjacent to the origin recognition complex binding site within the II/9A amplification origin, implying a role for ScEcR-A in amplification. Here, we extrapolate the molecular details from locus II/9A to the rest of the genome using immunofluorescence with a ScEcR-A-specific antibody. ScEcR-A binds all DNA puff sites just as amplification begins and persists throughout the processes of amplification, transcription, and puffing. Ecdysone injections into pre-amplification stage larvae prematurely induce both DNA amplification and ScEcR-A binding to DNA puff sites. These data are consistent with a direct role for ScEcR-A in DNA amplification.

Isolation and characterization of the ecdysone receptor and its heterodimeric partner ultraspiracle through development in Sciara coprophila.

Regulation of DNA replication is critical, and loss of control can lead to DNA amplification. Naturally occurring, developmentally regulated DNA amplification occurs in the DNA puffs of the late larval salivary gland giant polytene chromosomes in the fungus fly, Sciara coprophila. The steroid hormone ecdysone induces DNA amplification in Sciara, and the amplification origin of DNA puff II/9A contains a putative binding site for the ecdysone receptor (EcR). We report here the isolation, cloning, and characterizing of two ecdysone receptor isoforms in Sciara (ScEcR-A and ScEcR-B) and the heterodimeric partner, ultraspiracle (ScUSP). ScEcR-A is the predominant isoform in larval tissues and ScEcR-B in adult tissues, contrary to the pattern in Drosophila. Moreover, ScEcR-A is produced at amplification but is absent just prior. We discuss these results in relation to the model of ecdysone regulation of DNA amplification.