The nociceptive activity of peripheral sensory neurons is modulated by the neuronal membrane proteasome.

Proteasomes are critical for peripheral nervous system (PNS) function. Here, we investigate mammalian PNS proteasomes and reveal the presence of the neuronal membrane proteasome (NMP). We show that specific inhibition of the NMP on distal nerve fibers innervating the mouse hind paw leads to reduction in mechanical and pain sensitivity. Through investigating PNS NMPs, we demonstrate their presence on the somata and proximal and distal axons of a subset of dorsal root ganglion (DRG) neurons. Single-cell RNA sequencing experiments reveal that the NMP-expressing DRGs are primarily MrgprA3+ and Cysltr2+. NMP inhibition in DRG cultures leads to cell-autonomous and non-cell-autonomous changes in Ca2+ signaling induced by KCl depolarization, αß-meATP, or the pruritogen histamine. Taken together, these data support a model whereby NMPs are expressed on a subset of somatosensory DRGs to modulate signaling between neurons of distinct sensory modalities and indicate the NMP as a potential target for controlling pain.

Neuronal membrane proteasome-derived peptides modulate NMDAR-dependent neuronal signaling to promote changes in gene expression.

The neuronal membrane proteasome (NMP) degrades intracellular proteins into peptides that are released directly into the extracellular space, whereby they stimulate neurons to promote signaling mechanisms that remain unknown. Here, we demonstrate that neuronal stimulation promotes NMP activity and, subsequently, enhanced production of NMP peptides. We show that these neuronal activity-dependent NMP peptides can rapidly promote N-methyl-D-aspartate receptor (NMDAR)-dependent calcium influx in neurons. This leads to sustained phosphorylation of the well-defined stimulus-induced transcription factor, cyclic AMP response element (CRE)-binding protein (CREB). Downstream of these events, we identified changes to neuronal target genes which included increased expression of immediate early genes (e.g., Fos, Npas4, Egr4) and other genes known to have critical neuroregulatory roles. Further observations led to the discovery that NMP peptide-induced changes in gene expression is dependent on NMDARs and independent of AMPA receptors or voltage-gated sodium channels. These data demonstrate that NMP peptides are endogenous and selective activators of NMDA receptors and act as sufficient and novel stimuli within the context of neuronal activity-dependent signaling. This novel pathway is parallel to classic neuronal activity-dependent programs and points to NMP and its resulting peptides as potential modulators of neuronal function.

Orthogonal approaches required to measure proteasome composition and activity in mammalian brain tissue.

Proteasomes are large macromolecular complexes with multiple distinct catalytic activities that are each vital to human brain health and disease. Despite their importance, standardized approaches to investigate proteasomes have not been universally adapted. Here, we describe pitfalls and define straightforward orthogonal biochemical approaches essential to measure and understand changes in proteasome composition and activity in the mammalian central nervous system. Through our experimentation in the mammalian brain, we determined an abundance of catalytically active proteasomes exist with and without a 19S cap(s), the regulatory particle essential for ubiquitin-dependent degradation. Moreover, we learned that in-cell measurements using activity-based probes (ABPs) are more sensitive in determining the available activity of the 20S proteasome without the 19S cap and in measuring individual catalytic subunit activities of each ß subunit within all neuronal proteasomes. Subsequently, applying these tools to human brain samples, we were surprised to find that post-mortem tissue retained little to no 19S-capped proteasome, regardless of age, sex, or disease state. In comparing brain tissues (parahippocampal gyrus) from patients with Alzheimer's disease (AD) and unaffected individuals, the available 20S proteasome activity was significantly elevated in severe cases of AD, an observation not previously noted. Taken together, our study establishes standardized approaches for the comprehensive investigation of proteasomes in mammalian brain tissue, and we reveal new insight into brain proteasome biology.

Proteasome cap particle regulates synapses.

Deubiquitylation by free 19S proteasome cap particle modulates synaptic transmission.

The proteasome and its role in the nervous system.

Proteasomes are multisubunit complexes that catalyze the majority of protein degradation in mammalian cells to maintain protein homeostasis and influence the regulation of most cellular processes. The proteasome, a multicatalytic protease complex, is a ring-like structure with a narrow pore that exhibits regulated gating, enabling the selective degradation of target proteins into peptide fragments. This process of removing proteins is essential for eliminating proteins that are no longer wanted, such as unfolded or aggregated proteins. This is important for preserving cellular function relevant to brain health and disease. Recently, in the nervous system, specialized proteasomes have been shown to generate peptides with important cellular functions. These discoveries challenge the prevailing notion that proteasomes primarily operate to eliminate proteins and identify signaling-competent proteasomes. This review focuses on the structure, function, and regulation of proteasomes and sheds light on emerging areas of investigation regarding the role of proteasomes in the nervous system.

Effect of bariatric surgery on flow-mediated dilation and carotid intima-media thickness in patients with morbid obesity: 1-year follow-up study.

OBJECTIVE: Obesity is associated with increased cardiovascular (CV) mortality and morbidity. Bariatric surgery (BS) is currently an established therapeutic approach for severely obese patients. Carotid intima-media thickness (CIMT) and brachial artery flow-mediated dilation (FMD) provide important prognostic information beyond traditional CV risk factors. This study aimed to examine the effect of bariatric surgery-induced weight loss on CIMT and brachial artery FMD in morbidly obese patients. METHODS: A total of 23 morbidly obese patients (40.4±5.6 years, 13 females) were examined before and after BS for 1 year with 3-month periods. CIMT, FMD, body composition, and metabolic parameters were determined. RESULTS: All the patients exhibited significant weight loss following BS (p<0.001). Carotid intima-media thickness reduction was not significant from baseline to 6 months (p=0.069), but at 9 months (p=0.004), it became significant. Similarly, the difference between the preoperative and 6-month FMD assessments was not significant (p=0.057), but at 9 months (p<0.001), it became significant. CONCLUSION: Our study reveals that weight loss following BS causes improvements in CV risk factors, which is evident after 9 months of surgery.

Wernicke's Encephalopathy due to Non-Alcoholic Gastrointestinal Tract Disease.

INTRODUCTION: Wernicke's encephalopathy (WE) is an underdiagnosed neuropsychiatric disorder especially in non-alcoholic groups that causes morbidity-mortality if diagnosis is delayed. Korsakoff syndrome is a chronic consequence of this condition characterized by persistent memory impairment. In this study we present a series of non-alcoholic patients with WE. The purpose of this study was to analyze the predisposing factors in non-alcoholic patients with WE and emphasize the importance of early diagnosis and treatment with thiamine supplementation. METHODS: The clinical records of 6 cases with WE followed by gastrointestinal tract disease and/or surgery who were admitted to our Medical Faculty between 2012 and 2014 were retrospectively reviewed. RESULTS: The study included 3 men and 3 women in the age range of 24 to 55. All patients had gastrointestinal tract diseases and/or had undergone gastrointestinal surgeries, and were non-alcoholic. Vomiting, weight loss, and parenteral nutrition were the frequent precipitating factors. The classic triad of mental impairment, oculomotor alterations and gait ataxia was present in 4 of the 6 patients. Magnetic Resonance Imaging showed typical signal alterations in the medial thalami, mammillary bodies and the periaqueductal region of patients in various degrees. Clinical improvement was seen in each patient after thiamine supplementation. DISCUSSION: Physicians should be aware of the predisposing factors and symptoms to prevent or optimize the management of this potentially devastating disease. Thiamine supplementation should be considered in patients with gastrointestinal tract diseases or those who have undergone surgery.

Targeted DNA methylation in human cells using engineered dCas9-methyltransferases.

Mammalian genomes exhibit complex patterns of gene expression regulated, in part, by DNA methylation. The advent of engineered DNA methyltransferases (MTases) to target DNA methylation to specific sites in the genome will accelerate many areas of biological research. However, targeted MTases require clear design rules to direct site-specific DNA methylation and minimize the unintended effects of off-target DNA methylation. Here we report a targeted MTase composed of an artificially split CpG MTase (sMTase) with one fragment fused to a catalytically-inactive Cas9 (dCas9) that directs the functional assembly of sMTase fragments at the targeted CpG site. We precisely map RNA-programmed DNA methylation to targeted CpG sites as a function of distance and orientation from the protospacer adjacent motif (PAM). Expression of the dCas9-sMTase in mammalian cells led to predictable and efficient (up to ~70%) DNA methylation at targeted sites. Multiplexing sgRNAs enabled targeting methylation to multiple sites in a single promoter and to multiple sites in multiple promoters. This programmable de novo MTase tool might be used for studying mechanisms of initiation, spreading and inheritance of DNA methylation, and for therapeutic gene silencing.

Twelve-year trends in the prevalence and risk factors of diabetes and prediabetes in Turkish adults.

There is concern about an emerging diabetes epidemic in Turkey. We aimed to determine the prevalence of diagnosed and undiagnosed diabetes, prediabetes and their 12-year trends and to identify risk factors for diabetes in the adult Turkish population. A cross-sectional, population-based survey, 'TURDEP-II' included 26,499 randomly sampled adults aged ≥ 20 years (response rate: 87 %). Fasting glucose and biochemical parameters were measured in all; then a OGTT was performed to identify diabetes and prediabetes in eligible participants. The prevalence of diabetes was 16.5 % (new 7.5 %), translating to 6.5 million adults with diabetes in Turkey. It was higher in women than men (p = 0.008). The age-standardized prevalence to the TURDEP-I population (performed in 1997-98) was 13.7 % (if same diagnostic definition was applied diabetes prevalence is calculated 11.4 %). The prevalence of isolated-IFG and impaired glucose tolerance (IGT), and combined prediabetes was 14.7, 7.9, and 8.2 %, respectively; and that of obesity 36 % and hypertension 31.4 %. Compared to TURDEP-I; the rate of increase for diabetes: 90 %, IGT: 106 %, obesity: 40 % and central obesity: 35 %, but hypertension decreased by 11 % during the last 12 years. In women age, waist, body mass index (BMI), hypertension, low education, and living environment; in men age, BMI, and hypertension were independently associated with an increased prevalence of diabetes. In women current smoking, and in men being single were associated with a reduced risk. These results from one of the largest nationally representative surveys carried out so far show that diabetes has rapidly become a major public health challenge in Turkey. The figures are alarming and underscore the urgent need for national programs to prevent diabetes, to manage the illness and thus prevent complications.