Nedd4-2 up-regulation is associated with ACE2 ubiquitination in hypertension

AIMS

Angiotensin-converting enzyme 2 (ACE2) is a critical component of the compensatory renin-angiotensin system that is down-regulated during the development of hypertension, possibly via ubiquitination. However, little is known about the mechanisms involved in ACE2 ubiquitination in neurogenic hypertension. This study aimed at identifying ACE2 ubiquitination partners, establishing causal relationships and clinical relevance, and testing a gene therapy strategy to mitigate ACE2 ubiquitination in neurogenic hypertension.

METHODS AND RESULTS

Bioinformatics and proteomics were combined to identify E3 ubiquitin ligases associated with ACE2 ubiquitination in chronically hypertensive mice. In vitro gain/loss of function experiments assessed ACE2 expression and activity to validate the interaction between ACE2 and the identified E3 ligase. Mutation experiments were further used to generate a ubiquitination-resistant ACE2 mutant (ACE2-5R). Optogenetics, blood pressure telemetry, pharmacological blockade of GABAA receptors in mice expressing ACE2-5R in the bed nucleus of the stria terminalis (BNST), and capillary western analysis were used to assess the role of ACE2 ubiquitination in neurogenic hypertension. Ubiquitination was first validated as leading to ACE2 down-regulation, and Neural precursor cell-expressed developmentally down-regulated protein 4-2 (Nedd4-2) was identified as a E3 ligase up-regulated in hypertension and promoting ACE2 ubiquitination. Mutation of lysine residues in the C-terminal of ACE2 was associated with increased activity and resistance to angiotensin (Ang)-II-mediated degradation. Mice transfected with ACE2-5R in the BNST exhibited enhanced GABAergic input to the paraventricular nucleus (PVN) and a reduction in hypertension. ACE2-5R expression was associated with reduced Nedd4-2 levels in the BNST.

CONCLUSION

Our data identify Nedd4-2 as the first E3 ubiquitin ligase involved in ACE2 ubiquitination in Ang-II-mediated hypertension. We demonstrate the pivotal role of ACE2 on GABAergic neurons in the maintenance of an inhibitory tone to the PVN and the regulation of pre-sympathetic activity. These findings provide a new working model where Nedd4-2 could contribute to ACE2 ubiquitination, leading to the development of neurogenic hypertension and highlighting potential novel therapeutic strategies.

The Influence of Lipid Microdomain Heterogeneity on Protein-Protein Interactions: Proteomic Analysis of Co-Immunoprecipitated Binding Partners of P450 1A2 and P450 3A in Rat Liver Microsomes

Liver cytochrome P450s (CYPs) of the endoplasmic reticulum (ER) are involved in the metabolism of exogenous and endogenous chemicals. The ER is not uniform, but possesses ordered lipid microdomains containing higher levels of saturated fatty acids, sphingomyelin, and cholesterol and disordered regions containing higher levels of polyunsaturated fatty acid chains. The various forms of drug-metabolizing P450s partition to either the ordered or disordered lipid microdomains with different degrees of specificity. P450s readily form complexes with ER-resident proteins, including other forms of P450. This study aims to ascertain whether lipid microdomain localization influences protein-P450 interactions in rat liver microsomes. Thus, liver microsomes were co-immunoprecipitated with CYP1A2-specific and CYP3A-specific antibodies, and the co-immunoprecipitating proteins were identified by liquid chromatography mass spectrometry proteomic analysis. These two P450s preferentially partition to ordered and disordered microdomains, respectively. More than 100 proteins were co-immunoprecipitated with each P450. Segregation of proteins into different microdomains did not preclude their interaction. However, CYP3A interacted broadly with proteins from ordered microdomains, whereas CYP1A2 reacted with a limited subset of these proteins. This is consistent with the concept of lipid raft heterogeneity and may indicate that CYP1A2 is targeted to a specific type of lipid raft. Although many of the interacting proteins for both P450s were other-drug metabolizing enzymes, other interactions were also evident. The consistent CYP3A binding partners were predominantly involved in phase I/II drug metabolism; however, CYP1A2 interacted not only with xenobiotic metabolizing enzymes, but also with enzymes involved in diverse cellular responses such as ER stress and protein folding. SIGNIFICANCE STATEMENT: This work describes the protein interactomes in rat liver microsomes of two important cytochromes P450s (CYP1A2 and CYP3A) in drug metabolism and describes the relationship of the interacting proteins to lipid microdomain distribution.

Circulating Plasma Exosomal Proteins of Either SHIV-Infected Rhesus Macaque or HIV-Infected Patient Indicates a Link to Neuropathogenesis

Despite the suppression of human immunodeficiency virus (HIV) replication by combined antiretroviral therapy (cART), 50-60% of HIV-infected patients suffer from HIV-associated neurocognitive disorders (HAND). Studies are uncovering the role of extracellular vesicles (EVs), especially exosomes, in the central nervous system (CNS) due to HIV infection. We investigated links among circulating plasma exosomal (crExo) proteins and neuropathogenesis in simian/human immunodeficiency virus (SHIV)-infected rhesus macaques (RM) and HIV-infected and cART treated patients (Patient-Exo). Isolated EVs from SHIV-infected (SHIV-Exo) and uninfected (CTL-Exo) RM were predominantly exosomes (particle size < 150 nm). Proteomic analysis quantified 5654 proteins, of which 236 proteins (~4%) were significantly, differentially expressed (DE) between SHIV-/CTL-Exo. Interestingly, different CNS cell specific markers were abundantly expressed in crExo. Proteins involved in latent viral reactivation, neuroinflammation, neuropathology-associated interactive as well as signaling molecules were expressed at significantly higher levels in SHIV-Exo than CTL-Exo. However, proteins involved in mitochondrial biogenesis, ATP production, autophagy, endocytosis, exocytosis, and cytoskeleton organization were significantly less expressed in SHIV-Exo than CTL-Exo. Interestingly, proteins involved in oxidative stress, mitochondrial biogenesis, ATP production, and autophagy were significantly downregulated in primary human brain microvascular endothelial cells exposed with HIV+/cART+ Patient-Exo. We showed that Patient-Exo significantly increased blood-brain barrier permeability, possibly due to loss of platelet endothelial cell adhesion molecule-1 protein and actin cytoskeleton structure. Our novel findings suggest that circulating exosomal proteins expressed CNS cell markers-possibly associated with viral reactivation and neuropathogenesis-that may elucidate the etiology of HAND.

Abstract WMP18: Protection Against Dementia In Mouse VCID By Repetitive Hypoxic Conditioning: Cortical Proteomics Defines Disease And Disease Resilient Phenotypes

Introduction: Vascular cognitive impairment and dementia (VCID) exerts huge morbidity costs, and efficacious therapies are lacking. In a well-established mouse model of VCID, we recently documented in vivo an epigenetically-induced resilience to reference memory deficits by 2 mo of repetitive hypoxic conditioning (RHC) treatment prior to bilateral carotid artery stenosis-induced chronic cerebral hypoperfusion (CCH). The present study was undertaken to define the phenotypic basis of this cognition-protective effect.

Methods: Samples of prefrontal cortex from untreated and RHC-treated mice were obtained after 4 mo of CCH, along with samples from age-matched sham-CCH controls, and analyzed by mass spectrometry using TMTpro labels for quantification. Differentially expressed proteins were bioinformatically analyzed using IPA (Qiagen), with rigid thresholds/filters for fold-change, z-scores, and statistical significance applied.

Results: 5071 proteins were identified - 3975 of which were quantified - in the 3 experimental groups. Relative to the cortical proteome of controls, the cortex of memory-impaired CCH mice exhibited a downregulation of proteins involved in Nrf2 signaling and synaptogenesis signaling pathways, and an increase of proteins and related proinflammatory mediators participating in leukocyte extravasation signaling. In addition, gamma secretase levels were increased. Treatment with RHC prior to CCH abrogated the aforementioned Nrf2, synaptogenesis, and leukocyte signaling changes, increased proteins driving oxidative phosphorylation, Rho-mediated CXCR4 signaling, DNA repair, and diverse cell survival networks, and reduced protein enrichments in both apoptosis and necrosis signaling, and reactive oxygen species generating, pathways. Levels of both amyloid precursor protein and amyloid-beta levels, as well as tau, were also lower in RHC-treated, dementia-resilient mice.

Conclusions: These novel findings reveal potential mechanistic insights into relatively early changes in phenotype that characterize VCID and, in turn, how this phenotype is modified by an efficacious epigenetic therapeutic. Causal studies designed to confirm these multifactorial mechanisms of cognitive protection are warranted.

Mask, the Drosophila ankyrin repeat and KH domain-containing protein, affects microtubule stability

Proper regulation of microtubule (MT) stability and dynamics is vital for essential cellular processes, including axonal transportation and synaptic growth and remodeling in neurons. In the present study, we demonstrate that the Drosophila ankyrin repeat and KH domain-containing protein Mask negatively affects MT stability in both larval muscles and motor neurons. In larval muscles, loss-of-function of mask increases MT polymer length, and in motor neurons, loss of mask function results in overexpansion of the presynaptic terminal at the larval neuromuscular junctions (NMJs). mask genetically interacts with stathmin (stai), a neuronal modulator of MT stability, in the regulation of axon transportation and synaptic terminal stability. Our structure–function analysis of Mask revealed that its ankyrin repeats domain-containing N-terminal portion is sufficient to mediate Mask's impact on MT stability. Furthermore, we discovered that Mask negatively regulates the abundance of the MT-associated protein Jupiter in motor neuron axons, and that neuronal knocking down of Jupiter partially suppresses mask loss-of-function phenotypes at the larval NMJs. Taken together, our studies demonstrate that Mask is a novel regulator for MT stability, and such a role of Mask requires normal function of Jupiter.

Summary: Mask is a novel regulator of MT stability in Drosophila. Mask shows prominent interplay with two important modulators of MT, Tau and Stathmin (Stai), whose mutations are related to human diseases.

Transcriptome analysis reveals sexual disparities in gene expression in rat brain microvessels

Sex is an important determinant of brain microvessels (MVs) function and susceptibility to cerebrovascular and neurological diseases, but underlying mechanisms are unclear. Using high throughput RNA sequencing analysis, we examined differentially expressed (DE) genes in brain MVs from young, male, and female rats. Bioinformatics analysis of the 23,786 identified genes indicates that 298 (1.2%) genes were DE using False Discovery Rate criteria (FDR; p < 0.05), of which 119 (40%) and 179 (60%) genes were abundantly expressed in male and female MVs, respectively. Nucleic acid binding, enzyme modulator, and transcription factor were the top three DE genes, which were more highly expressed in male than female MVs. Synthesis of glycosylphosphatidylinositol (GPI), biosynthesis of GPI-anchored proteins, steroid and cholesterol synthesis, were the top three significantly enriched canonical pathways in male MVs. In contrast, respiratory chain, ribosome, and 3 ́-UTR-mediated translational regulation were the top three enriched canonical pathways in female MVs. Different gene functions of MVs were validated by proteomic analysis and western blotting. Our novel findings reveal major sex disparities in gene expression and canonical pathways of MVs and these differences provide a foundation to study the underlying mechanisms and consequences of sex-dependent differences in cerebrovascular and other neurological diseases.

Chronic binge alcohol and ovariectomy dysregulate omental adipose tissue metaboproteome in simian immunodeficiency virus-infected female macaques

Effective antiretroviral therapy (ART) has significantly reduced mortality of people living with HIV (PLWH), and the prevalence of at-risk alcohol use is higher among PLWH. Increased survival and aging of PLWH is associated with increased prevalence of metabolic comorbidities especially among menopausal women, and adipose tissue metabolic dysregulation may be a significant contributing factor. We examined the differential effects of chronic binge alcohol (CBA) administration and ovariectomy (OVX) on the omental adipose tissue (OmAT) proteome in a subset of simian immunodeficiency virus (SIV)-infected macaques of a longitudinal parent study. Quantitative discovery-based proteomics identified 1,429 differentially expressed proteins. Ingenuity Pathway Analysis (IPA) was used to calculate z-scores, or activation predictions, for functional pathways and diseases. Results revealed that protein changes associated with functional pathways centered around the "OmAT metaboproteome profile." Based on z-scores, CBA did not affect functional pathways of metabolic disease but dysregulated proteins involved in adenosine monophosphate-activated protein kinase (AMPK) signaling and lipid metabolism. OVX-mediated proteome changes were predicted to promote pathways involved in glucose- and lipid-associated metabolic disease. Proteins involved in apoptosis, necrosis, and reactive oxygen species (ROS) pathways were also predicted to be activated by OVX and these were predicted to be inhibited by CBA. These results provide evidence for the role of ovarian hormone loss in mediating OmAT metaboproteome dysregulation in SIV and suggest that CBA modifies OVX-associated changes. In the context of OVX, CBA administration produced larger metabolic and cellular effects, which we speculate may reflect a protective role of estrogen against CBA-mediated adipose tissue injury in female SIV-infected macaques.

Sexual differences in mitochondrial and related proteins in rat cerebral microvessels: A proteomic approach

Sex differences in mitochondrial numbers and function are present in large cerebral arteries, but it is unclear whether these differences extend to the microcirculation. We performed an assessment of mitochondria-related proteins in cerebral microvessels (MVs) isolated from young, male and female, Sprague-Dawley rats. MVs composed of arterioles, capillaries, and venules were isolated from the cerebrum and used to perform a 3 versus 3 quantitative, multiplexed proteomics experiment utilizing tandem mass tags (TMT), coupled with liquid chromatography/mass spectrometry (LC/MS). MS data and bioinformatic analyses were performed using Proteome Discoverer version 2.2 and Ingenuity Pathway Analysis. We identified a total of 1969 proteins, of which 1871 were quantified by TMT labels. Sixty-four proteins were expressed significantly (p < 0.05) higher in female samples compared with male samples. Females expressed more mitochondrial proteins involved in energy production, mitochondrial membrane structure, anti-oxidant enzyme proteins, and those involved in fatty acid oxidation. Conversely, males had higher expression levels of mitochondria-destructive proteins. Our findings reveal, for the first time, the full extent of sexual dimorphism in the mitochondrial metabolic protein profiles of MVs, which may contribute to sex-dependent cerebrovascular and neurological pathologies.

Oxidation of Cytochrome 605 Is the Rate-Limiting Step when Ferrimicrobium acidiphilum Respires Aerobically on Soluble Iron

Proteins that oxidize extracellular substrates in Gram-positive bacteria are poorly understood. Ferrimicrobium acidiphilum is an actinobacterium that respires aerobically on extracellular ferrous ions at pH 1.5. In situ absorbance measurements were conducted on turbid suspensions of intact Fm. acidiphilum using an integrating cavity absorption meter designed for that purpose. Initial velocity kinetic studies monitored the appearance of product ferric ions in the presence of catalytic quantities of cells. Cell-catalyzed iron oxidation obeyed the Michaelis-Menten equation with Km and Vmax values of 71 μM and 0.29 fmol/min/cell, respectively. Limited-turnover kinetic studies were conducted with higher concentrations of cells to detect and monitor changes in the absorbance properties of cellular redox proteins when the cells were exposed to limited quantities of soluble reduced iron. A single a-type cytochrome with reduced absorbance peaks at 448 and 605 nm was the only redox-active chromophore that was visible as the cells respired aerobically on iron. The reduced cytochrome 605 exhibited mathematical and correlational properties that were consistent with the hypothesis that oxidation of the cytochrome constituted the rate-limiting step in the aerobic respiratory process, with a turnover number of 35 ± 2 s-1 Genomic and proteomic analyses showed that Fm. acidiphilum could and did express only two a-type heme copper terminal oxidases. Cytochrome 605 was associated with the terminal oxidase gene that is located between nucleotides 31,090 and 33,039, inclusive, in the annotated circular genome of this bacterium.IMPORTANCE The identities and functions of proteins involved in aerobic respiration on extracellular ferrous ions at acidic pH are poorly understood in the four phyla of Gram-positive eukaryotes and archaea where such activities occur. In situ absorbance measurements were conducted on Fm. acidiphilum as it respired on extracellular iron using an integrating cavity absorption meter that permitted accurate optical measurements in turbid suspensions of the intact bacterium under physiological conditions. The significance of these measurements is that they permitted a direct spectrophotometric examination of the extents and rates of biological electron transfer events in situ under noninvasive physiological conditions without disrupting the complexity of the live cellular environment. One thing is certain: one way to understand how a protein functions in an intact organism is to actually observe that protein as it functions in the intact organism. This paper provides an example of just such an observation.

Intermittent Hypoxia Promotes Functional Neuroprotection from Retinal Ischemia in Untreated First-Generation Offspring: Proteomic Mechanistic Insights

Purpose

Stress can lead to short- or long-term changes in phenotype. Accumulating evidence also supports the transmission of maladaptive phenotypes, induced by adverse stressors, through the germline to manifest in subsequent generations, providing a novel mechanistic basis for the heritability of disease. In the present study in mice, we tested the hypothesis that repeated presentations of a nonharmful conditioning stress, demonstrated previously to protect against retinal ischemia, will also provide ischemic protection in the retinae of their untreated, first-generation (F1) adult offspring.

Methods

Swiss-Webster ND4 outbred mice were mated following a 16-week period of brief, every-other-day conditioning exposures to mild systemic hypoxia (repetitive hypoxic conditioning, RHC). Retinae of their 5-month-old F1 progeny were subjected to unilateral ischemia. Scotopic electroretinography quantified postischemic outcomes. The injury-resilient retinal proteome was revealed by quantitative mass spectrometry, and bioinformatic analyses identified the biochemical pathways and networks in which these differentially expressed proteins operate.

Results

Significant resilience to injury in both sexes was documented in F1 mice derived from RHC-treated parents, relative to matched F1 adult progeny derived from normoxic control parents. Ischemia-induced increases and decreases in the expression of many visual transduction proteins that are integral to photoreceptor function were abrogated by parental RHC, providing a molecular basis for the observed functional protection.

Conclusions

Our proteomic analyses provided mechanistic insights into the molecular manifestation of the inherited, injury-resilient phenotype. To our knowledge, this is the first study in a mammalian model documenting the reprogramming of heritability to promote disease resilience in the next generation.

Treatment with dimethyl fumarate reduces the formation and rupture of intracranial aneurysms: Role of Nrf2 activation

Oxidative stress and chronic inflammation in arterial walls have been implicated in intracranial aneurysm (IA) formation and rupture. Dimethyl fumarate (DMF) exhibits immunomodulatory properties, partly via activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway which reduces oxidative stress by inducing the antioxidant response element (ARE). This study evaluated the effects of DMF both in vitro, using tumor necrosis factor (TNF)-α-treated vascular smooth muscle cells (VSMC), and in vivo, using a murine elastase model to induce aneurysm formation. The mice were treated with either DMF at 100 mg/kg/day P.O. or vehicle for two weeks. DMF treatment protected VSMCs from TNF-α-induced inflammation as demonstrated by its downregulation of cytokines and upregulation of Nrf2 and smooth muscle cell markers. At higher doses, DMF also inhibited the pro-proliferative action of TNF-α by increasing apoptosis which protected the cells from aponecrosis. In mice, DMF treatment significantly decreased the incidence of aneurysm formation and rupture, at the same time increasing Nrf2 levels. DMF demonstrated a neuroprotective effect in mice with a resultant inhibition of oxidative stress, inflammation, and fibrosis in the cerebrovasculature. This suggests a potential role for DMF as a rescue therapy for patients at risk for formation and rupture of IAs.

A comprehensive analysis of sialolith proteins and the clinical implications

BACKGROUND

Sialolithiasis or salivary gland stones are associated with high clinical morbidity. The advances in the treatment of sialolithiasis has been limited, however, by our understanding of their composition. More specifically, there is little information regarding the formation and composition of the protein matrix, the role of mineralogical deposition, or the contributions of cell epithelium and secretions from the salivary glands. A better understanding of these stone characteristics could pave the way for future non-invasive treatment strategies.

METHODS

Twenty-nine high-quality ductal stone samples were analyzed. The preparation included successive washings to avoid contamination from saliva and blood. The sialoliths were macerated in liquid nitrogen and the maceration was subjected to a sequential, four-step, protein extraction. The four fractions were pooled together, and a standardized aliquot was subjected to tandem liquid chromatography mass spectrometry (LCMS). The data output was subjected to a basic descriptive statistical analysis for parametric confirmation and a subsequent G.O.-KEGG data base functional analysis and classification for biological interpretation.

RESULTS

The LC-MS output detected 6934 proteins, 824 of which were unique for individual stones. An example of our sialolith protein data is available via ProteomeXchange with the identifier PXD012422. More important, the sialoliths averaged 53% homology with bone-forming proteins that served as a standard comparison, which favorably compared with 62% homology identified among all sialolith sample proteins. The non-homologous protein fraction had a highly variable protein identity. The G.O.-KEGG functional analysis indicated that extracellular exosomes are a primary cellular component in sialolithiasis. Light and electron microscopy also confirmed the presence of exosomal-like features and the presence of intracellular microcrystals.

CONCLUSION

Sialolith formation presents similarities with the hyperoxaluria that forms kidney stones, which suggests the possibility of a common origin. Further verification of a common origin could fundamentally change the way in which lithiasis is studied and treated.

Differential Protein Expression Profiles of Bronchoalveolar Lavage Fluid Following Lipopolysaccharide-Induced Direct and Indirect Lung Injury in Mice

The pathogenic mechanisms of acute lung injury due to direct and indirect pulmonary insults are incompletely understood. Using an unbiased, discovery and quantitative proteomic approach, we examined bronchoalveolar lavage fluid (BALF) proteome following lipopolysaccharide (LPS)-induced direct and indirect lung injury in mice. A total of 1017 proteins were both identified and quantitated in BALF from control, intratracheal (I.T., direct) and intraperitoneal (I.P., indirect) LPS-treated mice. The two LPS groups shared 13 up-regulated and 22 down-regulated proteins compared to the control group. Ingenuity pathway analysis revealed that acute-phase response signaling was activated by both I.T. and I.P. LPS; however, the magnitude of activation was much greater in the I.T. LPS group. Intriguingly, two canonical signaling pathways, liver X receptor/retinoid X receptor activation, and the production of nitric oxide and reactive oxygen species in macrophages, were activated by I.T. but suppressed by I.P. LPS. Cxcl15 (also known as lungkine) was also up-regulated by I.T. but down-regulated by I.P. LPS. In conclusion, our quantitative discovery-based proteomic approach identified commonalities, as well as significant differences in BALF protein expression profiles between LPS-induced direct and indirect lung injury, and importantly, LPS-induced indirect lung injury resulted in suppression of select components of lung innate immunity.

5'-Iodotubercidin represses insulinoma-associated-1 expression, decreases cAMP levels, and suppresses human neuroblastoma cell growth

Insulinoma-associated-1 (INSM1) is a key protein functioning as a transcriptional repressor in neuroendocrine differentiation and is activated by N-Myc in human neuroblastoma (NB). INSM1 modulates the phosphoinositide 3-kinase (PI3K)-AKT Ser/Thr kinase (AKT)-glycogen synthase kinase 3β (GSK3β) signaling pathway through a positive-feedback loop, resulting in N-Myc stabilization. Accordingly, INSM1 has emerged as a critical player closely associated with N-Myc in facilitating NB cell growth. Here, an INSM1 promoter-driven luciferase-based screen revealed that the compound 5'-iodotubercidin suppresses adenosine kinase (ADK), an energy pathway enzyme, and also INSM1 expression and NB tumor growth. Next, we sought to dissect how the ADK pathway contributes to NB tumor cell growth in the context of INSM1 expression. We also found that 5'-iodotubercidin inhibits INSM1 expression and induces an intra- and extracellular adenosine imbalance. The adenosine imbalance, which triggers adenosine receptor-3 signaling that decreases cAMP levels and AKT phosphorylation and enhances GSK3β activity. We further observed that GSK3β then phosphorylates β-catenin and promotes the cytoplasmic proteasomal degradation pathway. 5'-Iodotubercidin treatment and INSM1 inhibition suppressed extracellular signal-regulated kinase 1/2 (ERK1/2) activity and the AKT signaling pathways required for NB cell proliferation. The 5'-iodotubercidin treatment also suppressed β-catenin, lymphoid enhancer-binding factor 1 (LEF-1), cyclin D1, N-Myc, and INSM1 levels, ultimately leading to apoptosis via caspase-3 and p53 activation. The identification of the signaling pathways that control the proliferation of aggressive NB reported here suggests new options for combination treatments of NB patients.

Comprehensive characterization of the adult ND4 Swiss Webster mouse retina: Using discovery-based mass spectrometry to decipher the total proteome and phosphoproteome

Purpose

Diverse groups of proteins play integral roles in both the physiology and pathophysiology of the retina. However, thorough proteomic analyses of retinas of experimental species are currently unavailable. The purpose of the present paper is providing the field with a comprehensive proteomic characterization of the retina of a commonly used laboratory mouse using a discovery-based mass spectrometry (MS) approach.

Methods

Retinas from eight male and eight female 30-week-old outbred ND4 Swiss Webster mice were harvested and immediately processed for MS analysis on a Thermo Fisher (TF) Fusion Orbitrap MS. The retinal proteome and phosphoproteome were identified and subsequently analyzed using Proteome Discoverer 2.2 and Panther-GeneGo. SEQUEST-HT scoring was used for analysis, and the reference protein FASTA database was from Mus musculus. Specifically, three technical repeats were performed for each biological sample. For characterization, only high-scoring peptides were considered, with a false discovery rate (FDR) of <1%. Downstream bioinformatic analysis used Ingenuity Pathway Analysis (IPA; Qiagen).

Results

Using Proteome Discoverer 2.2, 4,767 different proteins were identified and segregated into 26 major protein classes, 9 functional molecular classes, and 12 categories of biological processes. The five largest protein classes included the following: nucleic acid binding (17%), hydrolases (13%), enzyme modulators (10%), transferases (9%), and oxidoreductases (6%). "Binding" and "catalytic" proteins contributed to 81% of the molecular function class at 37% and 42%, respectively. "Cellular processing" and "metabolic processes" contributed the most to biologic activity, at 31% and 26%, respectively. Phosphopeptide enrichment yielded the identification of 610 additional unique proteins that were not originally identified. The two datasets combined produced an adult mouse retinal proteome consisting of 5,377 unique proteins. Overall, 41% of the retinal proteome was phosphorylated. The overwhelming diversity of retinal protein functionality was reflected through further analyses revealing 2,086 unique pathway hits across 241 different pathways (TF). A core analysis summary report was performed in IPA (Qiagen) to analyze the top signaling networks, protein-protein interaction (PPI) enrichments, and canonical pathways.

Conclusions

Using this high-throughput technique, we have further deciphered and updated the diverse proteome of the mouse retina, including the phosphoproteome, thereby providing the most comprehensive proteomic profile for this tissue known to date. These findings, and the bioinformatic analyses we also provided, establish a platform for future studies, facilitating the elucidation of the relevance of these proteins to the molecular and cellular pathologies that underlie retinal function and disease.

Molecular determinants of the human α2C-adrenergic receptor temperature-sensitive intracellular traffic

The human α2C-adrenergic receptor (α2C-AR) is localized intracellularly at physiologic temperature. Decreasing the environmental temperature strongly stimulates the receptor transport to the cell surface. In contrast, rat and mouse α2C-AR plasma membrane levels are less sensitive to decrease in temperature, whereas the opossum α2C-AR cell surface levels are not changed in these conditions. Structural analysis demonstrated that human α2C-AR has a high number of arginine residues in the third intracellular loop and in the C-terminus, organized as putative RXR motifs. Although these motifs do not affect the receptor subcellular localization at 37°C, deletion of the arginine clusters significantly enhanced receptor plasma membrane levels at reduced temperature. We found that this exaggerated transport of the human receptor is mediated by two functional arginine clusters, one in the third intracellular loop and one in the C-terminus. This effect is mediated by interactions with COPI vesicles, but not by 14-3-3 proteins. In rat α2C-AR, the arginine cluster from the third intracellular loop is shifted to the left due to three missing residues. Reinsertion of these residues in the rat α2C-AR restored the same temperature sensitivity as in the human receptor. Proteomic and coimmunoprecipitation experiments identified pontin as a molecule having stronger interactions with human α2C-AR compared with rat α2C-AR. Inhibition of pontin activity enhanced human receptor plasma membrane levels and signaling at 37°C. Our results demonstrate that human α2C-AR has a unique temperature-sensitive traffic pattern within the G protein-coupled receptor class due to interactions with different molecular chaperones, mediated in part by strict spatial localization of specific arginine residues.

Regulation of ROCKII by localization to membrane compartments and binding to DynaminI

ROCKII kinase activity is known to be regulated by Rho GTPase binding; however, the context-specific regulation of ROCKII is not clearly understood. We pursued the C-terminal PH domain as a candidate domain for regulating ROCKII function. A proteomics-based screen identified potential ROCKII signaling partners, a large number of which were associated with membrane dynamics. We used subcellular fractionation to demonstrate that ROCKII is localized to both the plasma membrane and internal endosomal membrane fractions, and then used microscopy to show that the C-terminal PH domain can localize to internal or peripheral membrane compartments, depending on the cellular context. Co-immunoprecipitation demonstrated that Dynamin1 is a novel ROCKII binding partner. Furthermore, blocking Dynamin function with a dominant negative mutant mimicked the effect of inhibiting ROCK activity on the actin cytoskeleton. Our data suggest that ROCKII is regulated by localization to specific membrane compartments and its novel binding partner, Dynamin1.

Reversible denaturation of oligomeric human chaperonin 10: denatured state depends on chemical denaturant

Chaperonins cpn60/cpn10 (GroEL/GroES in Escherichia coli) assist folding of nonnative polypeptides. Folding of the chaperonins themselves is distinct in that it entails assembly of a sevenfold symmetrical structure. We have characterized denaturation and renaturation of the recombinant human chaperonin 10 (cpn10), which forms a heptamer. Denaturation induced by chemical denaturants urea and guanidine hydrochloride (GuHCl) as well as by heat was monitored by tyrosine fluorescence, far-ultraviolet circular dichroism, and cross-linking; all denaturation reactions were reversible. GuHCl-induced denaturation was found to be cpn10 concentration dependent, in accord with a native heptamer to denatured monomer transition. In contrast, urea-induced denaturation was not cpn10 concentration dependent, suggesting that under these conditions cpn10 heptamers denature without dissociation. There were no indications of equilibrium intermediates, such as folded monomers, in either denaturant. The different cpn10 denatured states observed in high [GuHCl] and high [urea] were supported by cross-linking experiments. Thermal denaturation revealed that monomer and heptamer reactions display the same enthalpy change (per monomer), whereas the entropy-increase is significantly larger for the heptamer. A thermodynamic cycle for oligomeric cpn10, combining chemical denaturation with the dissociation constant in absence of denaturant, shows that dissociated monomers are only marginally stable (3 kJ/mol). The thermodynamics for co-chaperonin stability appears conserved; therefore, instability of the monomer could be necessary to specify the native heptameric structure.

Assessing cultural sensitivity in printed cancer materials

OBJECTIVES

Printed cancer education materials (PCEMs) (pamphlets and fact sheets) are used to educate individuals about cancer prevention and awareness. Culture is an important variable affecting the retention and use of information in printed materials to African Americans that has not been fully addressed in the literature.

MATERIALS AND METHODS

The major goal of the Cancer Prevention Materials for African Americans project, funded by the Texas Cancer Council, was to assess cultural sensitivity of currently disseminated PCEMs targeting African Americans. The project consisted of conducting focus groups, forming an advisory committee, and developing and using the Printed Cancer Education Materials for African Americans Cultural Sensitivity Assessment Tool.

RESULTS

Cultural sensitivity of PCEMs was assessed in terms of format, visual message, and written message. The majority of the PCEMs (56.2%) were culturally insensitive, with the visual message being the weakest component of all the materials.

CONCLUSION

Future PCEMs targeting African Americans should include culturally sensitive visual messages to be more effective in delivering the cancer prevention message. The use of the assessment tool can assist cancer control specialists in developing culturally sensitive materials.

Cost considerations as potential barriers to cancer treatment

PURPOSE

An analytical cross-sectional survey was conducted to determine the prevalence of barriers to cancer treatment in Texas as perceived by diagnosed cancer patients. Results reported here address the role of insurance coverage, indirect costs (transportation, lodging, and work days lost), and direct costs of care as barriers to treatment for white, black, and Hispanic cancer patients. Specific objectives of the analyses undertaken here are to examine 1) racial/ethnic differences in insurance coverage; 2) barriers relating to insurance coverage experienced by cancer patients; and 3) role of treatment-related costs as barriers to cancer treatment.

DESCRIPTION OF STUDY

A mail questionnaire was developed to assess the perceived barriers to cancer treatment in Texas for adult cancer patients, 17 years and older, who had been diagnosed with breast, colon, cervical, prostate, or lymphoma during the period of 1989 to 1993. The sampling frame for this study was obtained from a network of cancer treatment facilities throughout the state of Texas within the University of Texas M.D. Anderson Cancer Center Texas Community Oncology Network. A total of 593 cancer patients returned their surveys, yielding a 65.2% response rate. Weighting adjustments were then made to correct for differential sampling and response rates by racial groupings and type of cancer. All of the analyses used adjusted weights.

RESULTS

The findings document the financial considerations (insurance, direct and indirect costs) as they relate to barriers to cancer treatment. Specific insurance premium-related barriers with regard to maintaining and affording coverage were more prevalent for blacks. Hispanics were less likely to have insurance coverage; however, more blacks reported being denied insurance coverage when they changed jobs compared with whites and Hispanics. Minorities, particularly Hispanics, were more likely to have experienced cost-related barriers associated with medications, diagnostic tests, and hospitalizations. In addition, Hispanics experienced significant out-of-pocket costs in paying for cancer treatment.

CLINICAL IMPLICATIONS

This research shows the need for staff at cancer treatment facilities to be aware that there are nonclinical, financial factors that are important considerations in the treatment of cancer patients. Assessment of cancer patients during the diagnostic and treatment stages, possibly through case management, will provide information on potential barriers to treatment for individual patients. Hospital programs that reimburse out-of-pocket costs, transportation costs to obtain services, and lodging accommodations may be available. Additional services may be offered through cancer advocacy groups, such as the American Cancer Society and the National Coalition for Cancer Survivors, to assist patients with managing costs and overcoming barriers to care.

Cultural sensitivity and readability of breast and prostate printed cancer education materials targeting African Americans

Cancer prevention materials such as pamphlets, booklets, and fact sheets play a significant role in reducing cancer disparities. Little is documented in the literature about the cultural sensitivity of materials targeting African Americans. The Cancer Prevention Materials and African Americans project was conducted to assess the cultural sensitivity and readability of printed cancer education materials targeting African Americans. Results showed current breast and cancer materials are not written at appropriate reading levels, and only 54% of the breast and 40% of the prostate cancer materials were found to be culturally sensitive. Even though the materials are being developed and disseminated in health fairs, physician offices, barber shops, and other locations, the materials are still not reflective of the African-American populations and do not consider literacy, visual, written messages, and format as factors in their utilization. Future studies should assess the appropriateness of materials for African Americans to promote and prevent cancer in African Americans.

Information sources and barriers to cancer treatment by racial/ethnic minority status of patients

BACKGROUND

This study examined the sources used by cancer patients to obtain helpful information regarding their treatment options and side effects and the major predictors that facilitated usage of information.

METHODS

The survey was administered to a representative sample of cancer patients in Texas. The cancer treatment facilities from which the patients were sampled were part of the University of Texas M. D. Anderson Cancer Center's Texas Community Oncology Network. A total of 593 patients (65%) out of 910 contacted responded to the survey.

RESULTS

The patients reported that providers such as physicians and nurses were the most helpful sources of information. White patients tended to use books and reference materials more heavily to gather additional information regarding their treatment, while black patients relied on pamphlets and television. Educational level appeared to have a major influence on the black patient's use of printed materials.

CONCLUSIONS

The results document the important role that providers play in influencing patients' treatment decisions. Effective ways to communicate with cancer patients are different for patients with different racial backgrounds. Implications for the future development of patient education materials and cancer prevention initiatives targeting ethnic minorities are addressed.

Role of receptor binding in toxicity, immunogenicity, and adjuvanticity of Escherichia coli heat-labile enterotoxin

The role of receptor binding in the toxicity, immunogenicity, and adjuvanticity of the heat-labile enterotoxin of Escherichia coli (LT) was examined by comparing native LT and LT(G33D), a B-subunit receptor binding mutant, with respect to the ability to bind to galactose and to GM1, toxicity on mouse Y-1 adrenal tumor cells, the ability to stimulate adenylate cyclase in Caco-2 cells, enterotoxicity in the patent mouse model, and oral immunogenicity and adjuvanticity. In contrast to native LT, LT(G33D) was unable to bind to the galactosyl moiety of Sepharose 4B or GM1 but did retain the lectin-like ability to bind to immobilized galactose on 6% agarose beads. LT(G33D) had no enterotoxicity in the patent mouse model but exhibited residual toxicity on mouse Y-1 adrenal tumor cells and had an ability equivalent to that of native LT to stimulate adenylate cyclase in Caco-2 cells (5,000 versus 6,900 pmol per mg of protein). In addition, LT(G33D) was unable to serve as an effective oral adjuvant for induction of immunoglobulin G or A directed against a coadministered antigen. Furthermore, LT(G33D) elicited negligible serum and mucosal antibody responses against itself. These data indicate that the toxicity, immunogenicity, and oral adjuvanticity of LT are dependent upon binding of the B subunit to ganglioside GM1.

Transportation as a barrier to cancer treatment

PURPOSE

Patients with cancer must overcome many psychological, social, and economic barriers to obtain needed treatment. Because of the need for repeated visits for cancer treatment on either an outpatient or an inpatient basis, one of the major issues that patients with cancer must confront is that of arranging for transportation to care.

METHODS

This study compares the distance and mode of transportation to radiotherapy and chemotherapy and perceptions of transportation as a barrier to care among white, black, and Hispanic cancer patients receiving treatment from a consortium of cancer treatment facilities in Texas. A mail questionnaire was developed to assess the perceived barriers to cancer treatment for patients who had been diagnosed clinically with breast, colon, cervical, or prostate cancer, or lymphoma between 1989 and 1993. A total of 910 surveys were mailed to prospective participants. Of the surveys mailed, 593 were returned, yielding a 65.2% response rate. By race, the respondents included whites (42%), blacks (40%), Hispanics (15%), and Asian-Pacific Islanders (3%). Two respondents were 17 years of age; the remaining respondents were 18 years or older.

RESULTS

This study shows that some patients may forgo needed treatment because of problems with transportation. This was perceived as an issue more for minority patients than for white patients. Black and Hispanic patients consistently reported that barriers such as distance, access to an automobile, and availability of someone to drive them to the treatment center were potential major problems. The distance to the facilities was farther for whites than for blacks and Hispanics. Patients generally had to travel farther for chemotherapy than for radiotherapy.

CLINICAL IMPLICATIONS

Patients, particularly minorities, may opt to forgo needed care in the absence of available and affordable means of transportation to treatment facilities. These findings demonstrate the need for healthcare providers to be aware of the transportation problems that patients with cancer experience in obtaining treatment. Healthcare providers must work with patients, their families, and volunteer agencies in the community to facilitate transportation to cancer treatment services.

The role of informal and formal social support networks for patients with cancer

PURPOSE

In this study, the authors examined the role of informal and formal social support networks in mitigating barriers to cancer treatment among whites, blacks, and Hispanics, based on a representative sample of cancer patients in Texas.

DESCRIPTION OF STUDY

The sample frame for this study was obtained from the University of Texas M. D. Anderson Cancer Center's Texas Community Oncology Network, a consortium of cancer treatment facilities in Texas. Of the 910 patients who were contacted, 593 (65%) responded to the survey.

RESULTS

The results show the value of social support networks in assisting cancer patients with continuing treatment. An important finding indicated that health professionals do not provide information regarding social support groups to patients with cancer at the time of diagnosis. Fewer than half of the respondents were asked whether they would be interested in joining a formal social support group. Individuals of all racial/ethnic groups reported that the formal support groups provided emotional assistance. Minorities were more apt to report that the formal support groups helped with continuing treatment. In addition, informal social support networks, such as extended families and civic clubs, were seen as more helpful for blacks and Hispanics as compared with whites.

CLINICAL IMPLICATIONS

The need for formal and informal networks is indicated by the results of this study, which show that networks, such as relationships with family, friends, and relatives, play an important role in assisting patients in coping with their cancer. These networks are part of the patient's total treatment experience and must be acknowledged by healthcare professionals. A large number of patients are not asked to join social support groups, suggesting a need for training healthcare professionals to provide information regarding the potential benefits of support groups for cancer patients.

The readability levels of cancer-prevention materials targeting African Americans

BACKGROUND

Several studies have examined the readability levels of cancer-prevention materials, but the readability levels of materials targeting African Americans have not been documented. The Cancer Prevention Materials and African-Americans project, funded in 1994 by the Texas Cancer Council, was developed to assess the readability levels and cultural sensitivity of cancer-prevention materials targeting African Americans.

METHODS

This study assessed the readability of 100 cancer-prevention materials using McLaughlin's SMOG grading. Illustrations and point sizes were also examined by research staff members.

RESULTS

Seventy-two percent of the material contained illustrations and 88% were printed using a 12-point font. An overall mean SMOG grade of 9.32 was found, which suggests that ninth graders can read and comprehend the text.

CONCLUSIONS

Although this grade level is lower than those indicated by previous studies, many of the printed materials may not be appropriate for African Americans at high risk for cancer: those with low incomes and little education. Health professionals should focus on decreasing the reading levels of print materials, pretesting audiences to determine their actual reading levels, and examining other factors that influence readability and comprehension.

Barriers to cancer treatment: a review of published research

PURPOSE/OBJECTIVES

To review published research on barriers to cancer treatment to provide a foundation for subsequent research and program and policy development directed at diminishing these barriers.

DATA SOURCES

Relevant literature from medical and behavioral science data bases published between 1964 and 1994. Researchers reviewed 752 abstracts; they identified 160 articles that related directly to research on barriers to cancer treatment. Of these 160 articles, researchers chose 61 for a subsequent review using criteria to evaluate the strength of the study design and sampling procedures.

DATA SYNTHESIS

The major barriers consistently documented to influence whether or not patients with cancer sought or continued treatment included communication problems between patients and providers, lack of information on side effects, cost of treatment, difficulties in obtaining and maintaining insurance coverage, and absence of social support networks. Access barriers generally were greater for older women, members of minority groups, and patients of lower socioeconomic status. The vast majority of the studies were conceptual or descriptive in nature and were based on nonprobability clinic-based samples.

CONCLUSIONS

The limitations of existing research point to the need for studies on barriers to cancer treatment based on analytic population-based study designs that examine the relative importance of factors derived from multivariate explanatory models. This information may be used to develop programs and policies to ameliorate treatment barriers for patients with cancer.

IMPLICATIONS FOR NURSING PRACTICE

The research priorities set forth by the Oncology Nursing Society also indicate a need for this type of research because quality of life, cost containment, and outcomes assessment all are directly or indirectly affected by the timely diagnosis of cancer. Treatment barriers have the potential to significantly affect an individual's ability to seek care and ultimately to increase the cost of care associated with adverse outcomes that may result from delays in seeking treatment.

Health expenditures in Texas during 1989 and 1990

To monitor the growth of the health-care sector in Texas, we made annual estimates of aggregate health spending in 1989 and 1990 and compared them with estimates from prior years and with national trends. Expenditures are grouped by total spending, spending by the state government, and distribution of payment. To achieve data that could be compared with national figures, we followed the methods used by the federal government to estimate national health spending. Results indicate a return to the rapid rates of growth experienced in the early 1980s. Possible explanations for some major trends in spending and in sources of payment are provided. Basic features of recent efforts to contain costs are addressed and related to the trends.

Health expenditures in Texas, 1988

Expenditures for health care in Texas during 1988 totaled $32.4 billion. Health spending by category of service and sources of payment was estimated and compared with estimates for prior years and with national trends. Texas differed from the nation as a whole in average annual increases in total spending, the percentage of spending for prepayment and administration, and the percentage of spending paid by consumers, the federal government, and private insurance. Proposed expansions in insurance coverage for the large proportion of uninsured Texans will probably require strong efforts to contain costs.