Altered COVID-19 immunity in children with asthma by atopic status.

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes a spectrum of clinical outcomes that may be complicated by severe asthma. Antiviral immunity is often compromised in patients with asthma; however, whether this is true for SARS-CoV-2 immunity and children is unknown. Objective: We aimed to evaluate SARS-CoV-2 immunity in children with asthma on the basis of infection or vaccination history and compared to respiratory syncytial viral or allergen (eg, cockroach, dust mite)-specific immunity. Methods: Fifty-three children from an urban asthma study were evaluated for medical history, lung function, and virus- or allergen-specific immunity using antibody or T-cell assays. Results: Polyclonal antibody responses to spike were observed in most children from infection and/or vaccination history. Children with atopic asthma or high allergen-specific IgE, particularly to dust mites, exhibited reduced seroconversion, antibody magnitude, and SARS-CoV-2 virus neutralization after SARS-CoV-2 infection or vaccination. TH1 responses to SARS-CoV-2 and respiratory syncytial virus correlated with antigen-respective IgG. Cockroach-specific T-cell activation as well as IL-17A and IL-21 cytokines negatively correlated with SARS-CoV-2 antibodies and effector functions, distinct from total and dust mite IgE. Allergen-specific IgE and lack of vaccination were associated with recent health care utilization. Reduced lung function (forced expiratory volume in 1 second ≤ 80%) was independently associated with (SARS-CoV-2) peptide-induced cytokines, including IL-31, whereas poor asthma control was associated with cockroach-specific cytokine responses. Conclusion: Mechanisms underpinning atopic and nonatopic asthma may complicate the development of memory to SARS-CoV-2 infection or vaccination and lead to a higher risk of repeated infection in these children.

Racism behind the screen: Examining the mediating and moderating relationships between anonymity, online disinhibition, and cyber-racism.

Cyber-racism has emerged as a societal issue that affects many youths and adults; however, no published work has elucidated the psychological processes germane to predicting cyber-racism perpetration. Theory-without data to support its postulates-argues that online disinhibition mediates the relationship between anonymity afforded the online user and cyber-racism. The purpose of the current research was to examine this prediction and add to the theory by testing additional mediators and moderators. Six empirical studies tested this theory with U.S. adults, and results reliably showed that online disinhibition mediated the relationship between anonymity and cyber-racism. Moreover, we also found evidence to suggest that (a) this mediated effect remained while controlling for real-world variables, (b) the mediated effect was moderated by racial prejudice, (c) the mediated effect was moderated by cyberbullying perpetration, and (d) that certain types of online disinhibition are stronger mediators than others. Finally, Study 7 synthesized these six studies and found evidence for the mediating influence of online disinhibition in the relationship between anonymity and cyber-racism. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Understanding Cyber-Racism Perpetration within the Broader Context of Cyberbullying Theory: A Theoretical Integration.

The purpose of the current theoretical review is to argue for the theoretical integration of cyber-racism perpetration into the broader cyberbullying context-making note of the similarities between both types of nefarious online behavior that make this integration appropriate and the differences that make the integration less clear. Cyber-racism and cyberbullying victimization have been shown to be prevalent in youth and is related to poor psychological outcomes. Understanding both types of antisocial online behaviors have implications for the understanding and subsequent reduction of cyber-racism. Our review focuses on a cyber-racism model that proposes the importance of anonymity perceptions afforded to the online user to cause cyber-racism via several routes that focus on (a) online disinhibition, (b) deindividuation and group polarization, and (c) stereotypes. We discuss the tenets of this theory and the overlap with the Barlett Gentile Cyberbullying Model-a learning-based model that focuses on how anonymity eventually predicts cyberbullying via the development of positive cyberbullying attitudes. We believe that theoretical integration is necessary; however, future work needs to test several theoretical underpinnings of these models first. We end with a discussion of theoretical and intervention implications before discussing limitations and future work. Overall, we hope this review sparks interesting future research to understand cyber-racism and broaden the existing research on cyberbullying.

Stroke-related risk factors during pregnancy in women who underwent metabolic and bariatric surgery compared with women who have not undergone metabolic and bariatric surgery.

BACKGROUND: Stroke during pregnancy is rare, occurring in 30 of 100,000 pregnancies and accounting for 7% of maternal deaths in the United States from 2016 to 2018. Metabolic and bariatric surgery (MBS) has been shown to reduce symptoms of chronic conditions that are risk factors for stroke, including hypertension, hypercholesterolemia, and diabetes in women. However, little is known about the impact of MBS on stroke risk during pregnancy. OBJECTIVES: To examine stroke and stroke risk factors including preeclampsia, eclampsia, gestational hypertension, and embolism/thrombosis in women of reproductive age who have had MBS. SETTING: We used the National Inpatient Sample, a publicly available data set from the Healthcare Cost and Utilization Project that samples 20% of hospital discharges in the United States. METHODS: This cross-sectional study included women between the ages of 20 and 44 years who had a maternal admission code. Weighted logistic regression was conducted to assess the odds of stroke and stroke risk factors in women with a history of MBS compared with other women of reproductive age. RESULTS: Women with a history of MBS have 12% lower adjusted odds of developing preeclampsia/eclampsia and 10% lower adjusted odds of gestational hypertension than women who did not undergo MBS. When stratified by race, the difference was significant in White women (preeclampsia/eclampsia: adjusted odds ratio [aOR] = .89; 95% confidence interval [CI], .81-.98; gestational hypertension: aOR = .91; 95% CI, .83-1.00). Latinas with MBS had significantly lower odds of preeclampsia/eclampsia (aOR = .75; 95% CI, .64-.90). CONCLUSIONS: MBS helps women lose weight and decrease the incidence of some pregnancy-related risk factors for stroke. However, there is a notable racial health disparity.

Lymphoma-associated acquired von Willebrand syndrome responsive to splenectomy: A case report.

A previously healthy 33-year-old female presented with a large hematoma over her right knee after kneeling. She was found to have pancytopenia and massive splenomegaly. Von Willebrand Factor (VWF) antigen level was 0.38 units/ml, ristocetin cofactor activity 0.13 units/ml, and VWF multimeric distribution was normal. Bone marrow examination revealed an indolent B-cell lymphoma. Diagnosis was consistent with acquired von Willebrand syndrome as an autoimmune epiphenomenon of a lymphoma. Diagnostic and therapeutic splenectomy under hemostatic coverage was performed. VWF antigen levels and activities immediately normalized postoperatively and remained within the normal range several months later. Splenic pathology confirmed hairy cell leukemia with a BRAF mutation.

Profiling the New Zealand Police Trainee Physical Competency Test.

Police officers require a certain amount of occupational fitness to successfully perform physically demanding tasks. As such, trainees are required to undergo training to develop their ability to perform such tasks. The physical competency test (PCT) is a 400 m obstacle course consisting of key police occupational physical tasks used to evaluate a trainee's ability to complete tasks that a police officer is expected to perform whilst on duty. The purpose of this study was to profile the PCT in a police recruit population to provide an indication of the current level of occupational fitness within a policing population to inform conditioning requirements. Retrospective data for 813 male (age = 27.41 ± 5.92 years, body mass = 83.98 ± 14.03 kg, height = 179.23 ± 10.50 cm, BMI = 25.85 ± 3.92 kg/m2) and 372 female (mean age = 27.01 ± 6.45 years, mean weight = 67.14 ± 8.60 kg, mean height = 168.14 ± 6.46 cm and mean BMI = 23.61 ± 2.52 kg/m2) police trainees from the New Zealand Police Constabulary Recruitment database were provided for analysis. Anthropometric data, including height, body mass, and BMI were provided, in addition to trainee PCT time. Data were split by sex and age. Significant differences were observed between sexes for all anthropometric measures and PCT time (p < 0.001). Generally, in both the male and female groups, younger recruits tended to perform better than the older recruits with results between the "under 20" and the 20-24-year-old-age groups performing significantly better than the 35-39-year-old-age group in both sexes, and the 25-29-year-old-age group performing significantly better than the 35-39-year-old-age group in female officers. The data provided in this study provides a profile for performance of male and female recruits of various ages on the PCT in preparation for entry, or re-entry following injury, into the NZ Police. However, given that the PCT is considered a measure of occupational task performance, consideration should be given to the use of sex and age neutral requirements as the occupational tasks performed by police officers exhibit the same traits regardless of sex or age. Older trainees may therefore need conditioning to improve PCT times and subsequently occupational performance.

Prognostic Value of Programmed Death Ligand-1 Expression in Solid Tumors Irrespective of Immunotherapy Exposure: A Systematic Review and Meta-Analysis.

BACKGROUND: The programmed cell death-1/programmed cell death ligand-1 (PD-L1) pathway, which plays a crucial role in cancer immune surveillance, is the target of several approved immunotherapeutic agents and is used as a predictive biomarker in some solid tumors. However, its use as a prognostic marker (i.e., regardless of therapy used) is not established clearly with available data demonstrating inconsistent prognostic impact of PD-L1 expression in solid tumors. METHODS: We conducted a systematic literature search of electronic databases and identified publications exploring the effect of PD-L1 expression on overall survival and/or disease-free survival. Hazard ratios were pooled in a meta-analysis using generic inverse-variance and random-effects modeling. We used the Deeks method to explore subgroup differences based on disease site, stage of disease, and method of PD-L1 quantification. RESULTS: One hundred and eighty-six studies met the inclusion criteria. Programmed cell death ligand-1 expression was associated with worse overall survival (hazard ratio 1.33, 95% confidence interval 1.26-1.39; p < 0.001). There was significant heterogeneity between disease sites (subgroup p = 0.002) with pancreatic, hepatocellular, and genitourinary cancers associated with the highest magnitude of adverse outcomes. Programmed cell death ligand-1 was also associated with worse overall disease-free survival (hazard ratio 1.19, 95% confidence interval 1.09-1.30; p < 0.001). Stage of disease did not significantly affect the results (subgroup p = 0.52), nor did the method of quantification via immunohistochemistry or messenger RNA (subgroup p = 0.70). CONCLUSIONS: High expression of PD-L1 is associated with worse survival in solid tumors albeit with significant heterogeneity among tumor types. The effect is consistent in early-stage and metastatic disease and is not sensitive to method of PD-L1 quantification. These data can provide additional information for the counseling of patients with cancer about prognosis.

The Use of Fitness Testing to Predict Occupational Performance in Tactical Personnel: A Critical Review.

Tactical personnel work in an occupation that involves tasks requiring a high level of cardiovascular fitness as well as muscular strength and endurance. The aim of this literature review was to identify and critique studies investigating the relationship between physical fitness, quantified by fitness assessment measures, and occupational task performance. Databases were searched for relevant articles which assessed a fitness measure and a measure of occupational performance. A total of 15 articles were included and were deemed to be of acceptable methodological quality (8.4/12 on the Critical Appraisal Skills Programme checklist). Included articles assessed a variety of fitness attributes and occupational tasks. Across tactical groups, there appear to be no standardized fitness tests that can determine occupational performance, with aerobic fitness, anaerobic fitness, strength, endurance, power, and agility all being associated with occupational task performance. A wide range of fitness assessments appears to be required to predict occupational performance within tactical personnel. Efforts should be made to base fitness assessments on occupational demands unique to both the environment and requirements of each individual tactical unit.

Dietary intake of adults with and without diabetes: results from NHANES 2013-2016.

INTRODUCTION: Diet is a critical aspect of the management of adults with diabetes. This paper aims to compare dietary intakes of key macronutrients and micronutrients of US adults with and without diabetes and across the spectrum of diabetes. RESEARCH DESIGN AND METHODS: We compared absolute and energy-adjusted dietary intake of major macronutrients and micronutrients among those with and without diabetes and across the spectrum of glycemic control using a 24-hour dietary recall from a cross-sectional, nationally representative sample of 9939 US adults, 20+ years old (National Health and Nutrition Examination Survey 2013-2016). Diabetes was defined as an glycohemoglobin A1c (HbA1c)≥6.5%, fasting glucose ≥126 mg/dL, serum glucose at 2 hours following a 75 g glucose load (oral glucose tolerance test) ≥200 mg/dL, any diagnosis of diabetes or use of diabetes medication (self-reported). RESULTS: Percent of calories from macronutrients was similar for those with and without diabetes (p>0.05, energy adjusted and adjusted for age, race, and sex). In both groups, sugar accounted for about 20% of calories. Those with diabetes consumed about 7% more calcium (p=0.033), about 5% more sodium (p=0.026), and had lower diet quality (Healthy Eating Index-2015, p=0.021) than those without diabetes. Among those with diabetes, those with an HbA1c>9.0% consumed about 4% less magnesium (p-analysis of variance=0.007) than those with an HbA1c<6.5%. Results were similar within strata of age, race, and sex. Macronutrient intake did not vary consistently by HbA1c level. CONCLUSIONS: In this nationally representative sample, there were no substantial or consistent differences in the dietary intake of macronutrients or micronutrients between US adults with and without diabetes. Improving the diets of those with diabetes will likely require enhanced targeted efforts to improve the dietary intake of persons with diabetes, as well as broad efforts to improve the dietary intake of the general population.

Disease-Modifying Therapies During the COVID-19 Outbreak: A Narrative Review of International and National Recommendations.

BACKGROUND: Managing multiple sclerosis (MS) during the novel coronavirus disease 2019 (COVID-19) pandemic is a challenge due to the lack of evidence from clinical studies. Disease-modifying therapies (DMTs) may affect the immune response and subsequently alter the risk of COVID-19 infections. METHODS: A literature search was conducted on the MEDLINE, Embase, and Cochrane databases. A focused Google search was also performed. Recommendations regarding the use of DMTs during the COVID-19 outbreak from national and international MS/neurology societies were identified and reviewed. RESULTS: The review included 16 recommendations from international and national MS organizations. All recommendations are based on expert opinions. The recommendations regarding DMT initiation and management during this outbreak are summarized. Moreover, the experts' views about the risk of COVID-19 infection with each DMT are discussed. CONCLUSIONS: There is significant agreement among most experts' recommendations from a variety of sources based on collective clinical experience. However, the recommendations will likely evolve because sufficient clinical data are limited. Several ongoing registries will help provide information for future recommendations.

Molecular Analysis of Membrane Targeting by the C2 Domain of the E3 Ubiquitin Ligase Smurf1.

SMAD ubiquitination regulatory factor 1 (Smurf1) is a Nedd4 family E3 ubiquitin ligase that regulates cell motility, polarity and TGFß signaling. Smurf1 contains an N-terminal protein kinase C conserved 2 (C2) domain that targets cell membranes and is required for interactions with membrane-localized substrates such as RhoA. Here, we investigated the lipid-binding mechanism of Smurf1 C2, revealing a general affinity for anionic membranes in addition to a selective affinity for phosphoinositides (PIPs). We found that Smurf1 C2 localizes not only to the plasma membrane but also to negatively charged intracellular sites, acting as an anionic charge sensor and selective PIP-binding domain. Site-directed mutagenesis combined with docking/molecular dynamics simulations revealed that the Smurf1 C2 domain loop region primarily interacts with PIPs and cell membranes, as opposed to the ß-surface cationic patch employed by other C2 domains. By depleting PIPs from the inner leaflet of the plasma membrane, we found that PIP binding is necessary for plasma membrane localization. Finally, we used a Smurf1 cellular ubiquitination assay to show that the amount of ubiquitin at the plasma membrane interface depends on the lipid-binding properties of Smurf1. This study shows the mechanism by which Smurf1 C2 targets membrane-based substrates and reveals a novel interaction for non-calcium-dependent C2 domains and membrane lipids.

A systematic review of parent-infant interaction in infants at risk of autism.

Social communicative precursors to autism spectrum disorder may influence how infants who are later diagnosed with autism spectrum disorder interact with their social partners and the responses they receive, thus bidirectionally influencing early social experience. This systematic review aimed to identify a developmental timeline for parent-infant interaction in the first 2 years of life in at-risk infants and in emergent autism spectrum disorder, and to examine any parent-infant interaction associations with later social-communicative outcomes. In total, 15 studies were identified investigating parent-infant interaction in infants at familial autism risk (i.e. with an older sibling with autism spectrum disorder). Starting from the latter part of the first year, infants at risk of autism spectrum disorder (and particularly infants with eventual autism spectrum disorder) showed parent-infant interaction differences from those with no eventual autism spectrum disorder, most notably in infant gesture use and dyadic qualities. While parental interactions did not differ by subsequent child autism spectrum disorder outcome, at-risk infants may receive different 'compensatory' socio-communicative inputs, and further work is needed to clarify their effects. Preliminary evidence links aspects of parent-infant interaction with later language outcomes. We discuss the potential role of parent-infant interaction in early parent-mediated intervention.

Quercetin inhibits glucose transport by binding to an exofacial site on GLUT1.

Quercetin, a common dietary flavone, is a competitive inhibitor of glucose uptake and is also thought to be transported into cells by GLUT1. In this study, we confirm that quercetin is a competitive inhibitor of GLUT1 and also demonstrate that newly synthesized compounds, WZB-117 and BAY-876 are robust inhibitors of GLUT1 in L929 cells. To measure quercetin interaction with L929 cells, we develop a new fluorescent assay using flow cytometry. The binding of quercetin and its inhibitory effects on 2-deoxyglucose (2DG) uptake showed nearly identical dose dependent effects, with both having maximum effects between 50 and 100 µM and similar half maximum effects at 8.9 and 8.5 µM respectively. The interaction of quercetin was rapid with t1/2 of 54 s and the onset and loss of its inhibitory effects on 2DG uptake were equally fast. This suggests that either quercetin is simply binding to surface GLUT1 or its transport in and out of the cell reaches equilibrium very quickly. If quercetin is transported, the co-incubation of quercetin with other glucose inhibitors should block quercetin uptake. However, we observed that WZB-117, an exofacial binding inhibitor of GLUT1 reduced quercetin interaction, while cytochalasin B, an endofacial binding inhibitor, enhanced quercetin interaction, and BAY-876 had no effect on quercetin interaction. Taken together, these data are more consistent with quercetin simply binding to GLUT1, but not actually being transported into L929 cells via the glucose channel in GLUT1.

Specificity Protein 7 Is Required for Proliferation and Differentiation of Ameloblasts and Odontoblasts.

The Sp7/Osterix transcription factor is essential for bone development. Mutations of the Sp7 gene in humans are associated with craniofacial anomalies and osteogenesis imperfecta. However, the role of Sp7 in embryonic tooth development remains unknown. Here we identified the functional requirement of Sp7 for dentin synthesis and tooth development. Sp7-null mice exhibit craniofacial dysmorphogenesis and are completely void of alveolar bone. Surprisingly, initial tooth morphogenesis progressed normally in Sp7-null mice. Thus the formation of alveolar bone is not a prerequisite for tooth morphogenesis. Sp7 is required for mineralization of palatal tissue but is not essential for palatal fusion. The reduced proliferative capacity of Sp7-deficient ectomesenchyme results in small and misshapen teeth with randomly arranged cuboidal preodontoblasts and preameloblasts. Sp7 promotes functional maturation and polarization of odontoblasts. Markers of mature odontoblast (Col1a, Oc, Dspp, Dmp1) and ameloblast (Enam, Amelx, Mmp20, Amtn, Klk4) are barely expressed in incisors and molar tissues of Sp7-null mice. Consequently, dentin and enamel matrix are absent in the Sp7-null littermates. Interestingly, the Sp7 expression is restricted to cells of the dental mesenchyme indicating the effect on oral epithelium-derived ameloblasts is cell-nonautonomous. Abundant expression of Fgf3 and Fgf8 ligand was noted in the developing tooth of wild-type mice. Both ligands were remarkably absent in the Sp7-null incisor and molar, suggesting cross-signaling between mesenchyme and epithelium is disrupted. Finally, promoter-reporter assays revealed that Sp7 directly controls the expression of Fgf-ligands. Together, our data demonstrate that Sp7 is obligatory for the differentiation of both ameloblasts and odontoblasts but not for the initial tooth morphogenesis. © 2018 American Society for Bone and Mineral Research.

Multi-Scale Contingencies During Individual and Joint Action.

The present paper describes a joint action paradigm in which individuals or pairs utilized two computer keys to keep a dot stimulus moving inside a larger rectangle. Members of a pair could neither see nor hear each other. This paradigm allowed us to combine the discrete-trial type dependent variables (e.g., reaction time) commonly utilized by representational theorists, with the continuous, temporal dependence variables (e.g., RQA) utilized by dynamical theorists. Analysis revealed that individuals kept the dot in the rectangle longer than dyads and did so by moving it back and forth within the rectangle. Dyads, however, pressed their individual buttons as quickly as possible in order to keep the dot near the middle of the rectangle. These findings indicate that joint action constitutes a multi-scale phenomena that is best investigated via multiple, complementary methodologies versus single-measure, competing theories.

Notes and tips for improving quality of lipid-protein overlay assays.

To reduce costs of lipid-binding assays, allow for multiple lipids to be screened for protein binding simultaneously, and to make lipid binding more user friendly, lipids have been dotted onto membranes to investigate lipid-protein interactions. These assays are similar to a western blot where the membrane is blocked, incubated with a protein of interest and detected using antibodies. Although the assay is inexpensive and straightforward, problems with promiscuous or poor binding, as well as insufficient blocking occur frequently. In this technical note, we share several specific improvements to ensure lipid-protein overlay assays are of high quality and contain proper controls.

The Ebola Virus matrix protein, VP40, requires phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) for extensive oligomerization at the plasma membrane and viral egress.

VP40 is one of eight proteins encoded by the Ebola Virus (EBOV) and serves as the primary matrix protein, forming virus like particles (VLPs) from mammalian cells without the need for other EBOV proteins. While VP40 is required for viral assembly and budding from host cells during infection, the mechanisms that target VP40 to the plasma membrane are not well understood. Phosphatidylserine is required for VP40 plasma membrane binding, VP40 hexamer formation, and VLP egress, However, PS also becomes exposed on the outer membrane leaflet at sites of VP40 budding, raising the question of how VP40 maintains an interaction with the plasma membrane inner leaflet when PS is flipped to the opposite side. To address this question, cellular and in vitro assays were employed to determine if phosphoinositides are important for efficient VP40 localization to the plasma membrane. Cellular studies demonstrated that PI(4,5)P2 was an important component of VP40 assembly at the plasma membrane and subsequent virus like particle formation. Additionally, PI(4,5)P2 was required for formation of extensive oligomers of VP40, suggesting PS and PI(4,5)P2 have different roles in VP40 assembly where PS regulates formation of hexamers from VP40 dimers and PI(4,5)P2 stabilizes and/or induces extensive VP40 oligomerization at the plasma membrane.

Host Cell Plasma Membrane Phosphatidylserine Regulates the Assembly and Budding of Ebola Virus.

UNLABELLED: Lipid-enveloped viruses replicate and bud from the host cell where they acquire their lipid coat. Ebola virus, which buds from the plasma membrane of the host cell, causes viral hemorrhagic fever and has a high fatality rate. To date, little has been known about how budding and egress of Ebola virus are mediated at the plasma membrane. We have found that the lipid phosphatidylserine (PS) regulates the assembly of Ebola virus matrix protein VP40. VP40 binds PS-containing membranes with nanomolar affinity, and binding of PS regulates VP40 localization and oligomerization on the plasma membrane inner leaflet. Further, alteration of PS levels in mammalian cells inhibits assembly and egress of VP40. Notably, interactions of VP40 with the plasma membrane induced exposure of PS on the outer leaflet of the plasma membrane at sites of egress, whereas PS is typically found only on the inner leaflet. Taking the data together, we present a model accounting for the role of plasma membrane PS in assembly of Ebola virus-like particles. IMPORTANCE: The lipid-enveloped Ebola virus causes severe infection with a high mortality rate and currently lacks FDA-approved therapeutics or vaccines. Ebola virus harbors just seven genes in its genome, and there is a critical requirement for acquisition of its lipid envelope from the plasma membrane of the human cell that it infects during the replication process. There is, however, a dearth of information available on the required contents of this envelope for egress and subsequent attachment and entry. Here we demonstrate that plasma membrane phosphatidylserine is critical for Ebola virus budding from the host cell plasma membrane. This report, to our knowledge, is the first to highlight the role of lipids in human cell membranes in the Ebola virus replication cycle and draws a clear link between selective binding and transport of a lipid across the membrane of the human cell and use of that lipid for subsequent viral entry.

Cellular and molecular interactions of phosphoinositides and peripheral proteins.

Anionic lipids act as signals for the recruitment of proteins containing cationic clusters to biological membranes. A family of anionic lipids known as the phosphoinositides (PIPs) are low in abundance, yet play a critical role in recruitment of peripheral proteins to the membrane interface. PIPs are mono-, bis-, or trisphosphorylated derivatives of phosphatidylinositol (PI) yielding seven species with different structure and anionic charge. The differential spatial distribution and temporal appearance of PIPs is key to their role in communicating information to target proteins. Selective recognition of PIPs came into play with the discovery that the substrate of protein kinase C termed pleckstrin possessed the first PIP binding region termed the pleckstrin homology (PH) domain. Since the discovery of the PH domain, more than ten PIP binding domains have been identified including PH, ENTH, FYVE, PX, and C2 domains. Representative examples of each of these domains have been thoroughly characterized to understand how they coordinate PIP headgroups in membranes, translocate to specific membrane docking sites in the cell, and function to regulate the activity of their full-length proteins. In addition, a number of novel mechanisms of PIP-mediated membrane association have emerged, such as coincidence detection-specificity for two distinct lipid headgroups. Other PIP-binding domains may also harbor selectivity for a membrane physical property such as charge or membrane curvature. This review summarizes the current understanding of the cellular distribution of PIPs and their molecular interaction with peripheral proteins.

Emerging methodologies to investigate lipid-protein interactions.

Cellular membranes are composed of hundreds of different lipids, ion channels, receptors and scaffolding complexes that act as signalling and trafficking platforms for processes fundamental to life. Cellular signalling and membrane trafficking are often regulated by peripheral proteins, which reversibly interact with lipid molecules in highly regulated spatial and temporal fashions. In most cases, one or more modular lipid-binding domain(s) mediate recruitment of peripheral proteins to specific cellular membranes. These domains, of which more than 10 have been identified since 1989, harbour structurally selective lipid-binding sites. Traditional in vitro and in vivo studies have elucidated how these domains coordinate their cognate lipids and thus how the parent proteins associate with membranes. Cellular activities of peripheral proteins and subsequent physiological processes depend upon lipid binding affinities and selectivity. Thus, the development of novel sensitive and quantitative tools is essential in furthering our understanding of the function and regulation of these proteins. As this field expands into new areas such as computational biology, cellular lipid mapping, single molecule imaging, and lipidomics, there is an urgent need to integrate technologies to detail the molecular architecture and mechanisms of lipid signalling. This review surveys emerging cellular and in vitro approaches for studying protein-lipid interactions and provides perspective on how integration of methodologies directs the future development of the field.