Cul3 regulates cytoskeleton protein homeostasis and cell migration during a critical window of brain development

De novo loss of function mutations in the ubiquitin ligase-encoding gene Cullin3 (CUL3) lead to autism spectrum disorder (ASD). Here, we used Cul3 mouse models to evaluate the consequences of Cul3 mutations in vivo. Our results show that Cul3 haploinsufficient mice exhibit deficits in motor coordination as well as ASD-relevant social and cognitive impairments. Cul3 mutant brain displays cortical lamination abnormalities due to defective neuronal migration and reduced numbers of excitatory and inhibitory neurons. In line with the observed abnormal columnar organization, Cul3 haploinsufficiency is associated with decreased spontaneous excitatory and inhibitory activity in the cortex. At the molecular level, employing a quantitative proteomic approach, we show that Cul3 regulates cytoskeletal and adhesion protein abundance in mouse embryos. Abnormal regulation of cytoskeletal proteins in Cul3 mutant neuronal cells results in atypical organization of the actin mesh at the cell leading edge, likely causing the observed migration deficits. In contrast to these important functions early in development, Cul3 deficiency appears less relevant at adult stages. In fact, induction of Cul3 haploinsufficiency in adult mice does not result in the behavioral defects observed in constitutive Cul3 haploinsufficient animals. Taken together, our data indicate that Cul3 has a critical role in the regulation of cytoskeletal proteins and neuronal migration and that ASD-associated defects and behavioral abnormalities are primarily due to Cul3 functions at early developmental stages

Cul3 regulates cytoskeleton protein homeostasis and cell migration during a critical window of brain development

De novo loss of function mutations in the ubiquitin ligase-encoding gene Cullin3 lead to autism spectrum disorder (ASD). In mouse, constitutive haploinsufficiency leads to motor coordination deficits as well as ASD-relevant social and cognitive impairments. However, induction of Cul3 haploinsufficiency later in life does not lead to ASD-relevant behaviors, pointing to an important role of Cul3 during a critical developmental window. Here we show that Cul3 is essential to regulate neuronal migration and, therefore, constitutive Cul3 heterozygous mutant mice display cortical lamination abnormalities. At the molecular level, we found that Cul3 controls neuronal migration by tightly regulating the amount of Plastin3 (Pls3), a previously unrecognized player of neural migration. Furthermore, we found that Pls3 cell-autonomously regulates cell migration by regulating actin cytoskeleton organization, and its levels are inversely proportional to neural migration speed. Finally, we provide evidence that cellular phenotypes associated with autism-linked gene haploinsufficiency can be rescued by transcriptional activation of the intact allele in vitro, offering a proof of concept for a potential therapeutic approach for ASDs

Population dynamics of sensory adaptation in cortical circuits

Our sensory systems are remarkably flexible, able to adjust and recalibrate as we move through environments composed of drastically different stimuli. This flexibility is achieved in part through sensory adaptation (SA), a process whereby brain circuits adjust neuronal activity based on the spatiotemporal context in which stimuli are encountered. Several functions have been proposed for SA, including the improvement of discrimination between stimuli, maximizing information transmission in the current sensory environment, and the reduction of metabolic costs. While SA has been extensively studied at the level of individual neurons on timescales of tens of milliseconds to a few seconds, little is known about SA over longer timescales or at the population level. Here, we investigate population-level SA in the barrel field of the mouse somatosensory cortex (S1BF), which processes whisker inputs, using in vivo 2-photon calcium imaging and Neuropixels recordings of excitatory neurons in awake mice. Amongst stimulus responsive (SR) neurons we found both adapting and facilitating neurons that decreased or increased their firing with repetitive whisker stimulation, respectively. We also discovered that population SA to one stimulus frequency does not necessarily generalize to a different frequency. Moreover, responses of individual neurons to repeated rounds of stimulation were strikingly heterogeneous and stochastic, such that their adapting or facilitating response profile to the same stimulus was not stable across tens of minutes. Such representational drift was particularly striking when recording longitudinally across several days, as SA response profiles of most SR neurons changed drastically from one day to the next. Remarkably, repeated exposure to a familiar stimulus paradoxically shifted the population away from strong adaptation and toward facilitation. Finally, we investigated SST interneurons as a candidate network mechanism underlying population SA, and our preliminary results suggest they may modulate the balance between adaptation and facilitation in S1BF. Together, our studies indicate that the SA profile of S1BF neurons is not a fixed property of neurons, but rather highly a dynamic feature that is shaped by sensory experience across days. These findings provide valuable insight into the complex dynamics of population SA in S1BF and will serve as an important reference for future mechanistic studies of population SA as well as interrogations of its potential alteration in neurological and psychiatric conditions

Treatment Burden Discussion in Clinical Encounters: Priorities of COPD Patients, Carers and Physicians

PURPOSE: Many people with chronic obstructive pulmonary disease (COPD) feel overburdened with the treatment and management of their illness. Although research has begun to shed light on how COPD patients experience treatment burden, most of what we know is limited to personal experiences of patients. The aim of this study is to identify and prioritise areas of treatment burden that should be discussed during the clinical encounter from the perspectives of COPD patients, carers, and respiratory physicians. PATIENTS AND METHODS: Data were collected from participants using the nominal group technique. Five nominal group sessions were conducted in total (n = 31); three sessions with patients (n = 18), one with carers (n = 7) and another with respiratory physicians (pulmonologists or chest physicians) (n = 6). Each session was recorded and analyzed using thematic analysis. RESULTS: Going beyond understanding patients’ and carers’ experiences of treatment burden, this study offers a practical viewpoint of what should be discussed in a clinical encounter. Each group of participants contextualized treatment burden issues for discussion from their own perspectives. There was strong agreement, however, across the groups that difficulties accessing healthcare, lack of education and information, and worry about COPD treatment and prognosis were the most important treatment burden priorities for discussion. CONCLUSION: Understanding and creating opportunities to discuss these issues in a clinical encounter is important in not only reducing treatment burden but also improving health outcomes and quality of life for COPD patients and their carers

Patient and physician perspectives on treatment burden in end-stage kidney disease: a nominal group technique study

Objectives The treatment workload associated with end-stage kidney disease (ESKD) is high. The treatment burdens experienced by patients with ESKD are not well understood. In this study, we aimed to elucidate the most important areas of treatment burden for discussion in a clinical encounter from the perspectives of patients with ESKD and nephrologists. We sought to explore possible solutions to these high priority treatment burden challenges.Design Nominal group technique (NGT) sessions.Setting and participants Three in-person NGT sessions were conducted with 19 patients with dialysis-dependent ESKD from one tertiary treatment centre (mean age 64 years; range 47–82). All patients were either retired or on a disability pension; 74% perceived moderate or severe treatment burden; and 90% spent more than 11 hours on treatment-related activities per week (range 11–30). One online NGT session was conducted with six nephrologists from two Australian states.Main outcome measures The primary outcome was a ranked list of treatment burden priorities. The secondary outcome was potential solutions to these treatment burden challenges.Results Every patient group ranked health system issues as the most important treatment burden priority. This encompassed lack of continuity and coordination of care, dissatisfaction with frequent healthcare encounters and challenges around healthcare access. Psychosocial burdens on patients and families were perceived to be the most important area of treatment burden by physicians, and were ranked the second highest priority by patients.Conclusions Discussing treatment burden in a clinical encounter may lead to a better understanding of patients’ capacity to cope with their treatment workload. This could facilitate tailored care, improve health outcomes, treatment sustainability and patients’ overall quality of life