Chris Mullins

Ggas: A Family of Adp Ribosylation Factor-Binding Proteins Related to Adaptors and Associated with the Golgi Complex

Formation of intracellular transport intermediates and selection of cargo molecules are mediated by protein coats associated with the cytosolic face of membranes. Here, we describe a novel family of ubiquitous coat proteins termed GGAs, which includes three members in humans and two in yeast. GGAs have a modular structure consisting of a VHS domain, a region of homology termed GAT, a linker segment, and a region with homology to the ear domain of γ-adaptins. Immunofluorescence microscopy showed colocalization of GGAs with Golgi markers, whereas immunoelectron microscopy of GGA3 revealed its presence on coated vesicles and buds in the area of the TGN. Treatment with brefeldin A or overexpression of dominant-negative ADP ribosylation factor 1 (ARF1) caused dissociation of GGAs from membranes. The GAT region of GGA3 was found to: target a reporter protein to the Golgi complex; induce dissociation from membranes of ARF-regulated coats such as AP-1, AP-3, AP-4, and COPI upon overexpression; and interact with activated ARF1. Disruption of both GGA genes in yeast resulted in impaired trafficking of carboxypeptidase Y to the vacuole. These observations suggest that GGAs are components of ARF-regulated coats that mediate protein trafficking at the TGN.

AP-4, a Novel Protein Complex Related to Clathrin Adaptors

Here we report the identification and characterization of AP-4, a novel protein complex related to the heterotetrameric AP-1, AP-2, and AP-3 adaptors that mediate protein sorting in the endocytic and late secretory pathways. The key to the identification of this complex was the cloning and sequencing of two widely expressed, mammalian cDNAs encoding new homologs of the adaptor β and ς subunits named β4 and ς4, respectively. An antibody to β4 recognized in human cells an ∼83-kDa polypeptide that exists in both soluble and membrane-associated forms. Gel filtration, sedimentation velocity, and immunoprecipitation experiments revealed that β4 is a component of a multisubunit complex (AP-4) that also contains the ς4 polypeptide and two additional adaptor subunit homologs named μ4 (μ-ARP2) and ε. Immunofluorescence analyses showed that AP-4 is associated with the trans-Golgi network or an adjacent structure and that this association is sensitive to the drug brefeldin A. We propose that, like the related AP-1, AP-2, and AP-3 complexes, AP-4 plays a role in signal-mediated trafficking of integral membrane proteins in mammalian cells.

The MAPP research network: a novel study of urologic chronic pelvic pain syndromes

Urologic chronic pelvic pain syndrome (UCPPS) may be defined to include interstitial cystitis/bladder pain syndrome (IC/BPS) and chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). The hallmark symptom of UCPPS is chronic pain in the pelvis, urogenital floor, or external genitalia often accompanied by lower urinary tract symptoms. Despite numerous past basic and clinical research studies there is no broadly identifiable organ-specific pathology or understanding of etiology or risk factors for UCPPS, and diagnosis relies primarily on patient reported symptoms. In addition, there are no generally effective therapies. Recent findings have, however, revealed associations between UCPPS and “centralized” chronic pain disorders, suggesting UCPPS may represent a local manifestation of more widespread pathology in some patients. Here, we describe a new and novel effort initiated by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) of the U.S. National Institutes of Health (NIH) to address the many long standing questions regarding UCPPS, the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network. The MAPP Network approaches UCPPS in a systemic manner, in which the interplay between the genitourinary system and other physiological systems is emphasized. The network’s study design expands beyond previous research, which has primarily focused on urologic organs and tissues, to utilize integrated approaches to define patient phenotypes, identify clinically-relevant subgroups, and better understand treated natural history and pathophysiology. Thus, the MAPP Network provides an unprecedented, multi-layered characterization of UCPPS. Knowledge gained is expected to provide important insights into underlying pathophysiology, a foundation for better segmenting patients for future clinical trials, and ultimately translation into improved clinical management. In addition, the MAPP Network’s integrated multi-disciplinary research approach may serve as a model for studies of urologic and non-urologic disorders that have proven refractory to past basic and clinical study.Trial registrationClinicalTrials.gov identifier: NCT01098279 “Chronic Pelvic Pain Study of Individuals with Diagnoses or Symptoms of Interstitial Cystitis and/or Chronic Prostatitis (MAPP-EP)”.

The MAPP research network: design, patient characterization and operations

BackgroundThe “Multidisciplinary Approach to the Study of Chronic Pelvic Pain” (MAPP) Research Network was established by the NIDDK to better understand the pathophysiology of urologic chronic pelvic pain syndromes (UCPPS), to inform future clinical trials and improve clinical care. The evolution, organization, and scientific scope of the MAPP Research Network, and the unique approach of the network’s central study and common data elements are described.MethodsThe primary scientific protocol for the Trans-MAPP Epidemiology/Phenotyping (EP) Study comprises a multi-site, longitudinal observational study, including bi-weekly internet-based symptom assessments, following a comprehensive in-clinic deep-phenotyping array of urological symptoms, non-urological symptoms and psychosocial factors to evaluate men and women with UCPPS. Healthy controls, matched on sex and age, as well as “positive” controls meeting the non-urologic associated syndromes (NUAS) criteria for one or more of the target conditions of Fibromyalgia (FM), Chronic Fatigue Syndrome (CFS) or Irritable Bowel Syndrome (IBS), were also evaluated. Additional, complementary studies addressing diverse hypotheses are integrated into the Trans-MAPP EP Study to provide a systemic characterization of study participants, including biomarker discovery studies of infectious agents, quantitative sensory testing, and structural and resting state neuroimaging and functional neurobiology studies. A highly novel effort to develop and assess clinically relevant animal models of UCPPS was also undertaken to allow improved translation between clinical and mechanistic studies. Recruitment into the central study occurred at six Discovery Sites in the United States, resulting in a total of 1,039 enrolled participants, exceeding the original targets. The biospecimen collection rate at baseline visits reached nearly 100%, and 279 participants underwent common neuroimaging through a standardized protocol. An extended follow-up study for 161 of the UCPPS participants is ongoing.DiscussionThe MAPP Research Network represents a novel, comprehensive approach to the study of UCPPS, as well as other concomitant NUAS. Findings are expected to provide significant advances in understanding UCPPS pathophysiology that will ultimately inform future clinical trials and lead to improvements in patient care. Furthermore, the structure and methodologies developed by the MAPP Network provide the foundation upon which future studies of other urologic or non-urologic disorders can be based.Trial registrationClinicalTrials.gov identifier: NCT01098279 “Chronic Pelvic Pain Study of Individuals with Diagnoses or Symptoms of Interstitial Cystitis and/or Chronic Prostatitis (MAPP-EP)”. http://clinicaltrials.gov/show/NCT01098279

Defective expression of the μ3 subunit of the AP-3 adaptor complex in the Drosophila pigmentation mutant carmine

Abstract The adaptor protein (AP) complexes AP-1, AP-2, and AP-3 mediate coated vesicle formation and sorting of integral membrane proteins in the endocytic and late exocytic pathways in mammalian cells. A search of the Drosophila melanogaster expressed sequence tag (EST) database identified orthologs of family members mammalian medium (μ) chain families μ1, μ2, and μ3, of the corresponding AP complexes, and δ-COP, the analogous component of the coatomer (COPI) complex. The Drosophila orthologs exhibit a high degree of sequence identity to mammalian medium chain and δ-COP proteins. Northern analysis demonstrated that medium chain and δ-COP mRNAs are expressed uniformly throughout fly development. Medium chain and δ-COP genes were cytologically mapped and the μ3 gene was found to localize to a region containing the pigmentation locus carmine (cm). Analysis of genomic DNA of the cm1 mutant allele indicated the presence of a large insertion in the coding region of the μ3 gene and Northern analysis revealed no detectable μ3 mRNA. Light microscopy of the cm1 mutant showed a reduction in primary, secondary, and tertiary pigment granules in the adult eye. These findings provide evidence of a role for μ3 in the sorting processes required for pigment granule biogenesis in Drosophila.

Structural Requirements for Function of Yeast GGAs in Vacuolar Protein Sorting, α-Factor Maturation, and Interactions with Clathrin

ABSTRACT The GGAs (Golgi-localized, gamma-ear-containing, ARF-binding proteins) are a family of multidomain adaptor proteins involved in protein sorting at the trans-Golgi network of eukaryotic cells. Here we present results from a functional characterization of the two Saccharomyces cerevisiae GGAs, Gga1p and Gga2p. We show that deletion of both GGA genes causes defects in sorting of carboxypeptidase Y (CPY) and proteinase A to the vacuole, vacuolar morphology, and maturation of α-factor. A structure-function analysis reveals a requirement of the VHS, GAT, and hinge for function, while the GAE domain is less important. We identify putative clathrin-binding motifs in the hinge domain of both yeast GGAs. These motifs are shown to mediate clathrin binding in vitro. While mutation of these motifs alone does not block function of the GGAs in vivo, combining these mutations with truncations of the hinge and GAE domains diminishes function, suggesting functional cooperation between different clathrin-binding elements. Thus, these observations demonstrate that the yeast GGAs play important roles in the CPY pathway, vacuole biogenesis, and α-factor maturation and identify structural determinants that are critical for these functions.

Distinct requirements for the AP-3 adaptor complex in pigment granule and synaptic vesicle biogenesis in Drosophila melanogaster

Abstract The AP-3 adaptor protein complex has been implicated in the biogenesis of lysosome-related organelles, such as pigment granules/melanosomes, and synaptic vesicles. Here we compare the relative importance of AP-3 in the biogenesis of these organelles in Drosophila melanogaster. We report that the Drosophila pigmentation mutants orange and ruby carry genetic lesions in the σ3 and β3-adaptin subunits of the AP-3 complex, respectively. Electron microscopy reveals dramatic reductions in the numbers of electron-dense pigment granules in the eyes of these AP-3 mutants. Mutant flies also display greatly reduced levels of pigments housed in these granules. In contrast, electron microscopy of retinula cells reveals numerous synaptic vesicles in both AP-3 mutant and wild-type flies, while behavioral assays show apparently normal locomotor ability of AP-3 mutant larvae. Together, these results demonstrate that Drosophila AP-3 is critical for the biogenesis of pigment granules, but is apparently not essential for formation of a major population of synaptic vesicles in vivo.

Development of an evidence-based cognitive behavioral treatment program for men with chronic prostatitis/chronic pelvic pain syndrome

ObjectivesPsychosocial factors reported by patients with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) promote greater pain, disability, and ultimately poorer quality of life (QOL). We targeted those parameters in the development of a cognitive-behavioral (CB) program designed specifically for CP/CPPS.Methods and materialsFive NIH sponsored biopsychosocial studies examined predictors of pain, disability, and QOL in CP/CPPS men. Pain, urinary symptoms, QOL, depressive symptoms, catastrophic thinking about pain, perceived control over pain, pain-contingent resting as a pain coping measure, social support and interaction, sexual functioning, and relationship issues were assessed. These data showed that CB intervention for pain catastrophizing, pain contingent rest, social support and depressive symptoms is warranted for men with CP/CPPSResultsAn evidence based 8-week CB program was developed. The content of the CB sessions are defined in an instructional patient workbook for each of the weekly 1-h sessions. The CB program guides patients in examining the relationship between their symptom-based distress, their thinking at such times and the emotions linked with those thoughts, and their behavioral responses to their particular thinking style (e.g., illness vs. wellness focused). Patients complete such analyses by using a Reaction Record format, which also delineates new thinking/behavioral responses.ConclusionsThe CB program developed for CP/CPPS is the first comprehensive attempt to target specific evidence supported biopsychosocial variables for both symptom and QOL improvement in CP/CPPS and is expected to provide a useful tool for the clinical management of this chronic condition.

Prevalence, symptom impact and predictors of chronic prostatitis-like symptoms in Canadian males aged 16-19 years.

To estimate the prevalence and examine the extent that pain, urinary symptoms, depression and pain catastrophizing predict the quality of life (QoL) in Canadian male adolescents, as the prevalence and impact of chronic prostatitis (CP)‐like symptoms in adolescents is unknown.

Altered resting state neuromotor connectivity in men with chronic prostatitis/chronic pelvic pain syndrome: A MAPP: Research Network Neuroimaging Study.

Brain network activity associated with altered motor control in individuals with chronic pain is not well understood. Chronic Prostatitis/Chronic Pelvic Pain Syndrome (CP/CPPS) is a debilitating condition in which previous studies have revealed altered resting pelvic floor muscle activity in men with CP/CPPS compared to healthy controls. We hypothesized that the brain networks controlling pelvic floor muscles would also show altered resting state function in men with CP/CPPS. Here we describe the results of the first test of this hypothesis focusing on the motor cortical regions, termed pelvic-motor, that can directly activate pelvic floor muscles. A group of men with CP/CPPS (N = 28), as well as group of age-matched healthy male controls (N = 27), had resting state functional magnetic resonance imaging scans as part of the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network study. Brain maps of the functional connectivity of pelvic-motor were compared between groups. A significant group difference was observed in the functional connectivity between pelvic-motor and the right posterior insula. The effect size of this group difference was among the largest effect sizes in functional connectivity between all pairs of 165 anatomically-defined subregions of the brain. Interestingly, many of the atlas region pairs with large effect sizes also involved other subregions of the insular cortices. We conclude that functional connectivity between motor cortex and the posterior insula may be among the most important markers of altered brain function in men with CP/CPPS, and may represent changes in the integration of viscerosensory and motor processing.