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Synapse associated protein-97/Human Disk Large (SAP97/hDLG) is a conserved, alternatively spliced, modular, scaffolding protein critical in regulating the molecular organization of cell-cell junctions in vertebrates. We confirm that the molecular determinants of first order phase transition of SAP97/hDLG is controlled by morpho-functional changes in its nanoscale organization. Furthermore, the nanoscale molecular signatures of these signalling islands and phase transitions are altered in response to changes in cytosolic Ca 2+ . Additionally, exchange kinetics of alternatively spliced isoforms of the intrinsically disordered region in SAP97/hDLG C-terminus shows differential sensitivities to Ca 2+ bound Calmodulin, affirming that the molecular signatures of local phase transitions of SAP97/hDLG depends on their nanoscale heterogeneity and compositionality of isoforms. SAP97/hDLG is a ubiquitous, alternatively spliced, and conserved modular scaffolding protein involved in the organization cell junctions and excitatory synapses. Here, authors confirm that SAP97/hDLG condenses in to nanosized molecular domains in both heterologous cells and hippocampal pyramidal neurons. Authors demonstrate that in vivo and in vitro condensation, molecular signatures of nanoscale condensates and exchange kinetics of SAP97/hDLG is modulated by the local availability of alternatively spliced isoforms. Additionally, SAP97/hDLG isoforms exhibits a differential sensitivity to Ca 2+ bound Calmodulin, resulting in altered properties of nanocondensates and their real-time regulation

Maintaining a normal cholesterol balance is crucial for the functioning of a healthy brain. Dysregulation in cholesterol metabolism and homeostasis in the brain have been correlated to various neurological disorders. The majority of previous studies in primary cultures focus on the role of cholesterol balance in neuronal development after polarity has been established. Here we have investigated how transient alteration of membrane lipids, specifically cholesterol, affects neuronal development and polarity in developing hippocampal neurons prior to polarity establishment, soon after initiation of neurite outgrowth. We observed that temporary cholesterol perturbation affects axonal and dendritic development differentially in an opposing manner. Transient membrane cholesterol deficiency increased neuronal population with a single neurite, simultaneously generating a second population of neurons with supernumerary axons. Brief replenishment of cholesterol immediately after cholesterol sequestering rescued neuronal development defects and restored polarity. The results showed a small window of cholesterol concentration to be complementing neurite outgrowth, polarity reestablishment, and in determining the normal neuronal morphology, emphasizing the critical role of precise membrane lipid balance in defining the neuronal architecture. Membrane cholesterol enhancement modified neurite outgrowth but did not significantly alter polarity. Cholesterol sequestering at later stages of development has shown to enhance neurite outgrowth, whereas distinct effects for neurite development and polarity were observed at early developmental stages, signifying the relevance of precise membrane cholesterol balance in altering neuronal physiology. Our results confirm cholesterol to be a key determinant for axo-dendritic specification and neuronal architecture and emphasize the possibility to reverse neuronal developmental defects caused by cholesterol deficiency by modulating membrane cholesterol during the early developmental stages.

Alterations in the canonical processing of Amyloid Precursor Protein generate proteoforms that contribute to the onset of Alzheimer’s Disease. Modified composition of γ-secretase or mutations in its subunits has been directly linked to altered generation of Amyloid beta. Despite biochemical evidence about the role of γ-secretase in the generation of APP, the molecular origin of how spatial heterogeneity in the generation of proteoforms arises is not well understood. Here, we evaluated the localization of Nicastrin, a γ-secretase subunit, at nanometer sized functional zones of the synapse. With the help of super resolution microscopy, we confirm that Nicastrin is organized into nanodomains of high molecular density within an excitatory synapse. A similar nanoorganization was also observed for APP and the catalytic subunit of γ-secretase, Presenilin 1, that were discretely associated with Nicastrin nanodomains. Though Nicastrin is a functional subunit of γ-secretase, the Nicastrin and Presenilin1 nanodomains were either colocalized or localized independent of each other. The Nicastrin and Presenilin domains highlight a potential independent regulation of these molecules different from their canonical secretase function. The collisions between secretases and substrate molecules decide the probability and rate of product formation for transmembrane proteolysis. Our observations of secretase nanodomains indicate a spatial difference in the confinement of substrate and secretases, affecting the local probability of product formation by increasing their molecular availability, resulting in differential generation of proteoforms even within single synapses.

Aims The intermediate‐term effects of dietary protein on cardiometabolic risk factors in overweight and obese patients with heart failure and diabetes mellitus are unknown. We compared the effect of two calorie‐restricted diets on cardiometabolic risk factors in this population. Methods and results In this randomized controlled study, 76 overweight and obese (mean weight, 107.8 ± 20.8 kg) patients aged 57.7 ± 9.7 years, 72.4% male, were randomized to a high‐protein (30% protein, 40% carbohydrates, and 30% fat) or standard‐protein diet (15% protein, 55% carbohydrates, and 30% fat) for 3 months. Reductions in weight and cardiometabolic risks were evaluated at 3 months. Both diets were equally effective in reducing weight (3.6 vs. 2.9 kg) and waist circumference (1.9 vs. 1.3 cm), but the high‐protein diet decreased to a greater extent glycosylated haemoglobin levels (0.7% vs. 0.1%, P = 0.002), cholesterol (16.8 vs. 0.9 mg/dL, P = 0.031), and triglyceride (25.7 vs. 5.7 mg/dL, P = 0.032), when compared with the standard‐protein diet. The high‐protein diet also significantly improved both systolic and diastolic blood pressure than the standard‐protein diet (P < 0.001 and P = 0.040, respectively). Conclusions Both energy‐restricted diets reduced weight and visceral fat. However, the high‐protein diet resulted in greater reductions in cardiometabolic risks relative to a standard‐protein diet. These results suggest that a high‐protein diet may be more effective in reducing cardiometabolic risk in this population, but further trials of longer duration are needed.

Sixty-four percent of adults in America drink coffee daily, and caffeine is the main reason people tend to drink coffee habitually. Few studies have examined the association between caffeine and all-cause and cause-specific mortality. The objective of this study was to examine the association between caffeine and all-cause and cause-specific mortality using the National Health and Nutrition Examination Survey (NHANES) 1999–2014 database. The multivariate Cox proportional hazards regression model was used to examine 23,878 individuals 20 years and older. Daily caffeine intake was measured once at baseline. A total of 2206 deaths occurred, including 394 cardiovascular (CVD) deaths and 525 cancer deaths. Compared to those with a caffeine intake of <100 mg/day, the hazard ratios (HRs) for CVD mortality were significantly lower in the participants with a caffeine intake of 100–200 mg/day (HR, 0.63; 95% confidence interval [CI], 0.45–0.88), and those with a caffeine intake of >200 mg/day (HR, 0.67; 95% CI, 0.50–0.88) after adjusting for potential confounders. The HRs for all-cause mortality were significantly lower in the participants with a caffeine intake of 100–200 mg/day (HR, 0.78; 95% CI, 0.67–0.91), and those with a caffeine intake of >200 mg/day (HR, 0.68; 95% CI, 0.60–0.78). Subgroup analyses showed that caffeine may have different effects on all-cause mortality among different age and body mass index (BMI) groups. In conclusion, higher caffeine intake was associated with lower all-cause and CVD mortality.

Background The emergence of the less virulent COVID-19 strains such as Omicron and its subvariants shifted the paradigm of COVID-19 treatment from inpatient treatment to regular outpatient care. The individual health determinants affecting COVID-19 disease severity among vulnerable adults treated in outpatient settings are an under-researched area. Methods This study conducted in an outpatient COVID-19 antibody infusion center employed a cross-sectional survey design to explore the impact of comorbidities, general health status, and self-care self-efficacy on COVID-19 symptom severity. We recruited 120 COVID-19-positive participants over 40 years of age, of which 117 completed the study with 87 providing complete data. After the screening and consenting process, the participants completed the following surveys in a secure REDCap survey software (Vanderbilt University, Nashville, USA) on an iPad (Apple Inc., Cupertino, USA): 1) sociodemographic questionnaire, 2) Charlson Comorbidity Index (CCI) to capture comorbidities, 3) Medical Outcomes Study Short-Form (SF-12) to assess general health including physical (PCS) and mental (MCS) health subscales, 4) Self-Care Self-Efficacy Scale (SCSES) to measure self-care self-efficacy, and 5) the COVID-19 Symptom rating scale (COVID-19 SRS). Statistical analysis used were Chi-square and Pearson correlations.  Results As evidenced by CCI, the top five comorbidities were hypertension (42%), diabetes mellitus (31%), pulmonary disease (19%), depression (14%), and solid tumors (11%). Age was statistically significantly correlated to comorbidity burden (p<0.0001). Severe COVID-19 symptoms reported were fatigue, myalgia, cough, runny nose, and sore throat. The general health status measure (SF-12) subscales showed that the patient's mental component summary (MCS) was more statistically significant to COVID-19 symptom severity than the physical component summary (PCS). The MCS demonstrated a statistically significant correlation with fatigue and myalgia (p<0.0001), headache and breathing difficulties (p<0.001), nausea/vomiting (p<0.01), and abdominal pain/diarrhea (p<0.05). The PCS showed a lesser statistically significant correlation with fatigue, myalgia, headaches (p<0.01), fever/chills, cough, congestion/runny nose, night sweats, breathing difficulties, nausea/vomiting, and abdominal pain/diarrhea (p<0.05). Interestingly, the 'loss of smell' which is the hallmark symptom of COVID-19 was the only symptom that showed a statically significant correlation with the Charlson Comorbidity Index (p<0.05), and it did not show any association with either mental (SF-12 MCS) or physical (SF-12 PCS) health status. The SF-12 MCS also showed a statistically significant correlation with a diagnosis of depression (p< 0.01), validating it as a true measure of mental health among vulnerable adults. The SCSES was not correlated with any of the COVID-19 symptoms. Conclusions The patient's general health status, especially mental health was more statistically significant to COVID-19 symptoms. The COVID-19 hallmark symptom of 'loss of smell' was the only symptom that showed statistical significance with comorbidities. Within the limitations of a cross-sectional survey design and convenient sampling methods, this study calls to tailor general health status, especially mental health, and cumulative comorbidity burden to risk assessment/risk stratification of COVID-19 care.

In this work, fluorescence lifetime imaging microscopy in the time domain was used to study the fluorescence dynamics of ECFP and of the ratiometric chloride sensor Clomeleon along neuronal development. The multiexponential analysis of fluorophores combined with the study of the contributions of the individual lifetimes (decay-associated spectra) was used to discriminate the presence of energy transfer from other excited state reactions. A characteristic change of sign of the pre-exponential factors of lifetimes from positive to negative near the acceptor emission maxima was observed in presence of energy transfer. By fluorescence lifetime imaging microscopy, we could show that the individual conformations of CFP display differential quenching properties depending on their microenvironment. Suitability of Clomeleon as an optical indicator to obtain a direct readout of the intracellular chloride concentrations in living cells was verified by steady-state and time-resolved spectroscopy. The simultaneous study of the photophysical properties of Clomeleon, the calcium indicator Cameleon, and ECFP with neuronal development provided a kinetic model for the mechanism when competitive quenching effects as well as energy transfer occur in the same molecule. Simultaneous analysis of donor and acceptor kinetics was necessary to discriminate Försters resonance energy transfer along neuronal development due to the different cellular effects involved.

Neuromorphic cameras are a new class of dynamic-vision-inspired sensors that encode the rate of change of intensity as events. They can asynchronously record intensity changes as spikes, independent of the other pixels in the receptive field, resulting in sparse measurements. This recording of such sparse events makes them ideal for imaging dynamic processes, such as the stochastic emission of isolated single molecules. Here we show the application of neuromorphic detection to localize nanoscale fluorescent objects below the diffraction limit, with a precision below 20 nm. We demonstrate a combination of neuromorphic detection with segmentation and deep learning approaches to localize and track fluorescent particles below 50 nm with millisecond temporal resolution. Furthermore, we show that combining information from events resulting from the rate of change of intensities improves the classical limit of centroid estimation of single fluorescent objects by nearly a factor of two. Additionally, we validate that using post-processed data from the neuromorphic detector at defined windows of temporal integration allows a better evaluation of the fractalized diffusion of single particle trajectories. Our observations and analysis is useful for event sensing by nonlinear neuromorphic devices to ameliorate real-time particle localization approaches at the nanoscale. A neuromorphic camera can localize single fluorescent particles to below 20 nm resolution and evaluate the diffusion trajectory with millisecond temporal precision.

Recently, the localization of amyloid precursor protein (APP) into reversible nanoscale supramolecular assembly or “nanodomains” has been highlighted as crucial towards understanding the onset of the molecular pathology of Alzheimer’s disease (AD). Surface expression of APP is regulated by proteins interacting with it, controlling its retention and lateral trafficking on the synaptic membrane. Here, we evaluated the involvement of a key risk factor for AD, PICALM, as a critical regulator of nanoscale dynamics of APP. Although it was enriched in the postsynaptic density, PICALM was also localized to the presynaptic active zone and the endocytic zone. PICALM colocalized with APP and formed nanodomains with distinct morphological properties in different subsynaptic regions. Next, we evaluated if this localization to subsynaptic compartments was regulated by the C-terminal sequences of APP, namely, the “Y682ENPTY687” domain. Towards this, we found that deletion of C-terminal regions of APP with partial or complete deletion of Y682ENPTY687, namely, APP–Δ9 and APP–Δ14, affected the lateral diffusion and nanoscale segregation of APP. Lateral diffusion of APP mutant APP–Δ14 sequence mimicked that of a detrimental Swedish mutant of APP, namely, APP–SWE, while APP–Δ9 diffused similar to wild-type APP. Interestingly, elevated expression of PICALM differentially altered the lateral diffusion of the APP C-terminal deletion mutants. These observations confirm that the C-terminal sequence of APP regulates its lateral diffusion and the formation of reversible nanoscale domains. Thus, when combined with autosomal dominant mutations, it generates distinct molecular patterns leading to onset of Alzheimer’s disease (AD).