Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 22
Filter
1.
J Med Internet Res ; 2024 Jul 15.
Article in English | MEDLINE | ID: mdl-39009038

ABSTRACT

BACKGROUND: The leaders of healthcare institutions are grappling with rising expenses and surging demands for medical services. In response, they are increasingly embracing artificial intelligence (AI) technologies to improve patient care processes, alleviate operational burdens, and efficiently improve healthcare quality. OBJECTIVE: In this paper we will review the existing literature and synthesize insights on the role of leadership in driving AI transformation within the healthcare sector. METHODS: We conducted a comprehensive search across several databases, including MEDLINE (via Ovid), PsycINFO (via Ovid), CINAHL (via EBSCO), Business Source Premier (via EBSCO), and Canadian Business & Current Affairs (via ProQuest), spanning articles published from 2015 to June 2023 discussing AI transformation within the healthcare sector. Specifically, we focused on empirical studies with a particular emphasis on leadership. We used an inductive, thematic analysis approach to qualitatively map the evidence. The findings were reported in accordance with the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analysis extension for Scoping Reviews). RESULTS: A review of unique 2,813 abstracts led to the retrieval of 97 full-text articles for assessment, of which we included 22 articles for review. Our mapping of the literature reveals that leading AI transformation within the healthcare sector involves navigating a constantly changing landscape influenced by complex the various regulatory, technology and organization contexts. Technological, strategic, operational, and organizational leadership is required to drive AI transformation. Leadership across technical, adaptive, and interpersonal capacities is essential to navigate this transformation successfully. CONCLUSIONS: In conclusion, this review provides insights into the functional domains of leadership, the necessary leadership capacities, and the contextual factors that shape leadership behaviors related to AI transformation. Future research on AI in health care should investigate leadership as a crucial factor and examine the interconnectedness of functional domains, leadership capacities and context through rigorous research methodologies to enhance the existing evidence base.

2.
J Healthc Manag ; 67(5): 380-402, 2022.
Article in English | MEDLINE | ID: mdl-36074701

ABSTRACT

GOAL: Moral distress literature is firmly rooted in the nursing and clinician experience, with a paucity of literature that considers the extent to which moral distress affects clinical and administrative healthcare leaders. Moreover, the little evidence that has been collected on this phenomenon has not been systematically mapped to identify key areas for both theoretical and practical elaboration. We conducted a scoping review to frame our understanding of this largely unexplored dynamic of moral distress and better situate our existing knowledge of moral distress and leadership. METHODS: Using moral distress theory as our conceptual framework, we evaluated recent literature on moral distress and leadership to understand how prior studies have conceptualized the effects of moral distress. Our search yielded 1,640 total abstracts. Further screening with the PRISMA process resulted in 72 included articles. PRINCIPAL FINDINGS: Our scoping review found that leaders-not just their employees- personally experience moral distress. In addition, we identified an important role for leaders and organizations in addressing the theoretical conceptualization and practical effects of moral distress. PRACTICAL APPLICATIONS: Although moral distress is unlikely to ever be eliminated, the literature in this review points to a singular need for organizational responses that are intended to intervene at the level of the organization itself, not just at the individual level. Best practices require creating stronger organizational cultures that are designed to mitigate moral distress. This can be achieved through transparency and alignment of personal, professional, and organizational values.


Subject(s)
Organizational Culture , Stress, Psychological , Delivery of Health Care , Humans , Leadership , Morals
3.
Healthc Manage Forum ; 35(2): 80-85, 2022 Mar.
Article in English | MEDLINE | ID: mdl-35156410

ABSTRACT

The healthcare supply chain crisis surrounding Personal Protective Equipment (PPE) during the onset of the COVID-19 pandemic presented unique and complex challenges in achieving the primary aim of supply chain management, that is, delivering the right amount of the right supplies to the right people at the right time. This article describes the key findings from a case study on PPE supply chain responses to the COVID-19 pandemic in British Columbia (BC). It highlights a set of constructive response mechanisms to potential crises along healthcare supply chain. Effective and trusted leadership, a unity of purpose, integrated and robust digital infrastructure and capabilities, consistent learning, resilience building, and environmental sensing for reliable intelligence were found to be essential for preparing, for containing, and mitigating the crisis as it evolved across various phases of crisis management.


Subject(s)
COVID-19 , Pandemics , British Columbia/epidemiology , Delivery of Health Care , Humans , Pandemics/prevention & control , SARS-CoV-2
4.
Med Care Res Rev ; 79(4): 475-486, 2022 08.
Article in English | MEDLINE | ID: mdl-34474606

ABSTRACT

The global scale and unpredictable nature of the current COVID-19 pandemic have put a significant burden on health care and public health leaders, for whom preparedness plans and evidence-based guidelines have proven insufficient to guide actions. This article presents a review of empirical articles on the topics of "crisis leadership" and "pandemic" across medical and business databases between 2003 (since SARS) and-December 2020 and has identified 35 articles for detailed analyses. We use the articles' evidence on leadership behaviors and skills that have been key to pandemic responses to characterize the types of leadership competencies commonly exhibited in a pandemic context. Task-oriented competencies, including preparing and planning, establishing collaborations, and conducting crisis communication, received the most attention. However, people-oriented and adaptive-oriented competencies were as fundamental in overcoming the structural, political, and cultural contexts unique to pandemics.


Subject(s)
COVID-19 , Pandemics , Humans , Leadership , Public Health , SARS-CoV-2
5.
Int J Qual Health Care ; 33(1)2021 Mar 03.
Article in English | MEDLINE | ID: mdl-33128564

ABSTRACT

The COVID-19 pandemic has caused clinicians at the frontlines to confront difficult decisions regarding resource allocation, treatment options and ultimately the life-saving measures that must be taken at the point of care. This article addresses the importance of enacting crisis standards of care (CSC) as a policy mechanism to facilitate the shift to population-based medicine. In times of emergencies and crises such as this pandemic, the enactment of CSC enables concrete decisions to be made by governments relating to supply chains, resource allocation and provision of care to maximize societal benefit. This shift from an individual to a population-based societal focus has profound consequences on how clinical decisions are made at the point of care. Failing to enact CSC may have psychological impacts for healthcare providers particularly related to moral distress, through an inability to fully enact individual beliefs (individually focused clinical decisions) which form their moral compass.


Subject(s)
COVID-19/epidemiology , Emergencies , Health Care Rationing/organization & administration , Health Personnel/psychology , Quality of Health Care/organization & administration , Clinical Protocols/standards , Health Care Rationing/ethics , Health Care Rationing/standards , Health Personnel/ethics , Health Personnel/standards , Humans , Pandemics , Policy , Quality of Health Care/standards , SARS-CoV-2 , Stress, Psychological/epidemiology
6.
Int J Mol Sci ; 21(17)2020 Sep 01.
Article in English | MEDLINE | ID: mdl-32882943

ABSTRACT

Calmodulin binding is a nearly universal property of gap junction proteins, imparting a calcium-dependent uncoupling behavior that can serve in an emergency to decouple a stressed cell from its neighbors. However, gap junctions that function as electrical synapses within networks of neurons routinely encounter large fluctuations in local cytoplasmic calcium concentration; frequent uncoupling would be impractical and counterproductive. We have studied the properties and functional consequences of calmodulin binding to the electrical synapse protein Connexin 35 (Cx35 or gjd2b), homologous to mammalian Connexin 36 (Cx36 or gjd2). We find that specializations in Cx35 calmodulin binding sites make it relatively impervious to moderately high levels of cytoplasmic calcium. Calmodulin binding to a site in the C-terminus causes uncoupling when calcium reaches low micromolar concentrations, a behavior prevented by mutations that eliminate calmodulin binding. However, milder stimuli promote calcium/calmodulin-dependent protein kinase II activity that potentiates coupling without interference from calmodulin binding. A second calmodulin binding site in the end of the Cx35 cytoplasmic loop, homologous to a calmodulin binding site present in many connexins, binds calmodulin with very low affinity and stoichiometry. Together, the calmodulin binding sites cause Cx35 to uncouple only at extreme levels of intracellular calcium.


Subject(s)
Calmodulin/metabolism , Connexins/metabolism , Electrical Synapses/physiology , Gap Junctions/physiology , Calcium Signaling , Calcium-Calmodulin-Dependent Protein Kinase Type 2/metabolism , Calmodulin/genetics , Connexins/genetics , HeLa Cells , Humans , Mutation , Phosphorylation , Protein Binding , Protein Transport , Gap Junction delta-2 Protein
7.
eNeuro ; 7(2)2020.
Article in English | MEDLINE | ID: mdl-32179580

ABSTRACT

A variety of electrical synapses are capable of activity-dependent plasticity, including both activity-dependent potentiation and activity-dependent depression. In several types of neurons, activity-dependent electrical synapse plasticity depends on changes in the local Ca2+ environment. To enable study of local Ca2+ signaling that regulates plasticity, we developed a GCaMP Ca2+ biosensor fused to the electrical synapse protein Connexin 36 (Cx36). Cx36-GCaMP transfected into mammalian cell cultures formed gap junctions at cell-cell boundaries and supported Neurobiotin tracer coupling that was regulated by protein kinase A signaling in the same way as Cx36. Cx36-GCaMP gap junctions robustly reported local Ca2+ increases in response to addition of a Ca2+ ionophore with increases in fluorescence that recovered during washout. Recovery was strongly dependent on Na+-Ca2+ exchange activity. In cells transfected with NMDA receptor subunits, Cx36-GCaMP revealed transient and concentration-dependent increases in local Ca2+ on brief application of glutamate. In HeLa cells, glutamate application increased Cx36-GCaMP tracer coupling through a mechanism that depended in part on Ca2+, calmodulin-dependent protein kinase II (CaMKII) activity. This potentiation of coupling did not require exogenous expression of glutamate receptors, but could be accomplished by endogenously expressed glutamate receptors with pharmacological characteristics reminiscent of NMDA and kainate receptors. Analysis of RNA Sequencing data from HeLa cells confirmed expression of NMDA receptor subunits NR1, NR2C, and NR3B. In summary, Cx36-GCaMP is an effective tool to measure changes in the Ca2+ microenvironment around Cx36 gap junctions. Furthermore, HeLa cells can serve as a model system to study glutamate receptor-driven potentiation of electrical synapses.


Subject(s)
Calcium Signaling , Gap Junctions , Animals , Connexins/genetics , Connexins/metabolism , Gap Junctions/metabolism , HeLa Cells , Humans , Gap Junction delta-2 Protein
8.
Semin Perinatol ; 42(6): 361-368, 2018 10.
Article in English | MEDLINE | ID: mdl-30166054

ABSTRACT

Conjoined twins are a rare occurrence that offer unique challenges and circumstances to therapists. The overall goal of physical and occupational therapy treatment is to provide care that promotes developmental progression to two conjoined individuals with distinct personalities and potentially different physical and medical needs. The unique presentation of conjoined twins must be considered in determining therapeutic goals, interventions and plans of care. Providing therapeutic interventions throughout the NICU stay is a dynamic, evolving process, which challenges the therapy team to work together to find solutions. This paper aims to highlight the considerations, challenges, and strategies used to address barriers in the therapeutic care of conjoined twins.


Subject(s)
Aging/physiology , Occupational Therapy , Patient Care Planning , Physical Therapy Modalities , Twins, Conjoined , Weight-Bearing/physiology , Aging/psychology , Humans , Infant, Newborn , Patient Positioning/psychology , Personality , Quality of Life/psychology , Social Change , Twins, Conjoined/physiopathology , Twins, Conjoined/psychology
9.
Biosci Bioeng ; 4(4): 78-84, 2018 Dec.
Article in English | MEDLINE | ID: mdl-33005746

ABSTRACT

Calcium signals act as a ubiquitous secondary messenger in regulating many body functions. The detection of calcium microdomain signals is greatly facilitated by the existence of biomarker-targeted fluorescent probes. In this study, SRRF (super-resolution radial fluctuations) algorithm were used to compare the loci and the intensity of fluorescent probes before and after SRRF analysis. The implementation of SRRF algorithm was aimed for automatically resolving delicate and small calcium signals (to avoid the overlapped loci) on original images. For assessing the spatial accuracy of image intensity, immunofluorescence staining of retina cryostat slice for connexin 36 (Cx36) was microscopically imaged with or without the successive SRRF reconstruction. For characterizing the temporal association between SRRF and non-SRRF images, the changes of Cx36-GCaMP calcium indicator were recorded from transfected HeLa cells in response to the transient puffing of ionomycin. Image processing and analyses were conducted with Image J and Matlab. Through this study, SRRF reconstruction was found to confer an accurate measure for the identification of subcellular molecules, such as gap junctions. Compared with the conventional imaging, SRRF reconstruction generated better image resolution for the precise registration of individual signals. Temporally, the ratios of change in fluorescence intensity between SRRF and non-SRRF images were significantly correlated in the presence or absence of the subtraction of high background intensity. Quantitatively, the ratios of change in fluorescence intensity between SRRF and non-SRRF images with or without background subtraction were also significantly correlated. The merit of SRRF application on calcium live imaging was validated with the reporter gene system we worked on.

10.
Dev Neurobiol ; 77(5): 548-561, 2017 05.
Article in English | MEDLINE | ID: mdl-27402207

ABSTRACT

In the mammalian central nervous system, a remarkably small number of connexins is used in electrical synapses, with the majority formed from Cx36. A larger number has been detected in teleosts, with some seeming to serve restricted roles. Here, we report the discovery of a new connexin expressed in the zebrafish lens and a limited set of neurons. Zebrafish cx79.8 (gja8a), previously annotated incorrectly as cx50.5 based on a partial cDNA sequence, is a homologue of mammalian Cx50 (Gja8). We examined its expression through transgenic promoter-reporter constructs, in situ hybridization, and immunolabeling, and examined regulation of coupling in transfected HeLa cells. cx79.8 was expressed most strongly in the lens, but expression was also found in several groups of neurons in the cerebellum and related areas at the midbrain-hindbrain boundary, in cone photoreceptors, and in neurons in the retinal inner nuclear and ganglion cell layers. Labeling in the retina with antibodies against two C-terminal epitopes revealed numerous small punctate spots in the inner plexiform layer and along the somata of cones. Abundant gap junctions were labeled in the outer 1/3 of the lens, but were absent from the center, suggesting that the epitopes or the entire protein was absent from the center. Cx79.8 tracer coupling was strongly regulated by phosphorylation, and was extremely low in control conditions in HeLa cells due to protein phosphatase 2A activity. These properties allow coupling to be strongly restricted in situ, a frequently observed property for electrical synapses. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 548-561, 2017.


Subject(s)
Connexins/metabolism , Electrical Synapses/metabolism , Lens, Crystalline/metabolism , Neurons/metabolism , Zebrafish Proteins/metabolism , Zebrafish/metabolism , Animals , Female , HeLa Cells , Humans , Male
11.
J Cell Sci ; 128(21): 3888-97, 2015 Nov 01.
Article in English | MEDLINE | ID: mdl-26359298

ABSTRACT

Gap junctions formed of connexin 36 (Cx36, also known as Gjd2) show tremendous functional plasticity on several time scales. Changes in connexin phosphorylation modify coupling in minutes through an order of magnitude, but recent studies also imply involvement of connexin turnover in regulating cell-cell communication. We utilized Cx36 with an internal HaloTag to study Cx36 turnover and trafficking in cultured cells. Irreversible, covalent pulse-chase labeling with fluorescent HaloTag ligands allowed clear discrimination of newly formed and pre-existing Cx36. Cx36 in junctional plaques turned over with a half-life of 3.1 h, and the turnover rate was unchanged by manipulations of protein kinase A (PKA) activity. In contrast, changes in PKA activity altered coupling within 20 min. New Cx36 in cargo vesicles was added directly to existing gap junctions and newly made Cx36 was not confined to points of addition, but diffused throughout existing gap junctions. Existing connexins also diffused into photobleached areas with a half-time of less than 2 s. In conclusion, studies of Cx36-HaloTag revealed novel features of connexin trafficking and demonstrated that phosphorylation-based changes in coupling occur on a different time scale than turnover.


Subject(s)
Connexins/metabolism , Gap Junctions/metabolism , Animals , Brefeldin A/pharmacology , Cattle , Cell Communication/drug effects , Cell Communication/physiology , Cell Line , Fluorescence Recovery After Photobleaching , Gap Junctions/drug effects , HeLa Cells , Humans , Phosphorylation/drug effects , Phosphorylation/physiology , Gap Junction delta-2 Protein
12.
EJIFCC ; 26(1): 47-62, 2015 Jan.
Article in English | MEDLINE | ID: mdl-27683481

ABSTRACT

The ultimate goal of diagnostic testing is to guide disease management in order to improve patient outcomes and patient well-being. Patient populations are rarely homogenous and accurate diagnostic tests can dissect the patient population and identify those patients with similar symptoms but very different underlying pathophysiology that will respond differently to different treatments. This stratification of patients can direct patients to appropriate treatment and is likely to result in clinical benefits for patients and economic benefits for the healthcare system. In this article we look at the clinical and economic benefits afforded by clinical laboratory diagnostics in three disease areas that represent substantial clinical and healthcare burdens to society; heart failure, Alzheimer's disease and asthma.

15.
J Agric Food Chem ; 59(20): 10927-33, 2011 Oct 26.
Article in English | MEDLINE | ID: mdl-21913675

ABSTRACT

The physiological effects of the hydrolysates of white rice protein (WRP), brown rice protein (BRP), and soy protein (SP) hydrolyzed by the food grade enzyme, alcalase2.4 L, were compared to the original protein source. Male Syrian Golden hamsters were fed high-fat diets containing either 20% casein (control) or 20% extracted proteins or their hydrolysates as the protein source for 3 weeks. The brown rice protein hydrolysate (BRPH) diet group reduced weight gain 76% compared with the control. Animals fed the BRPH supplemented diet also had lower final body weight, liver weight, very low density lipoprotein cholesterol (VLDL-C), and liver cholesterol, and higher fecal fat and bile acid excretion than the control. Expression levels of hepatic genes for lipid oxidation, PPARα, ACOX1, and CPT1, were highest for hamsters fed the BRPH supplemented diet. Expression of CYP7A1, the gene regulating bile acid synthesis, was higher in all test groups. Expression of CYP51, a gene coding for an enzyme involved in cholesterol synthesis, was highest in the BRPH diet group. The results suggest that BRPH includes unique peptides that reduce weight gain and hepatic cholesterol synthesis.


Subject(s)
Dietary Fats/administration & dosage , Liver/chemistry , Plant Proteins/administration & dosage , Protein Hydrolysates/administration & dosage , Weight Gain/drug effects , Animals , Cholesterol/analysis , Cholesterol/biosynthesis , Cholesterol/blood , Cricetinae , Dietary Supplements , Feces/chemistry , Gene Expression , Lipid Peroxidation/genetics , Lipids/analysis , Lipids/blood , Liver/anatomy & histology , Liver/metabolism , Male , Mesocricetus , Organ Size/drug effects , Oryza/chemistry , Seeds/chemistry , Soybean Proteins/administration & dosage
16.
Blood Press Monit ; 13(3): 133-7, 2008 Jun.
Article in English | MEDLINE | ID: mdl-18496286

ABSTRACT

INTRODUCTION: Little is known about how and why patients use home blood pressure monitoring (HBPM). We investigated from where patients obtain their monitor, their reasons for using HBPM, and their frequency of performing blood pressure (BP) measurements. We also examined whether those using HBPM provide written reports of measurements to their doctor and whether they have ever had their monitor checked. METHODS: We conducted a cross-sectional mail survey of adult patients with hypertension enrolled in a practice-based research network of 24 primary care practices throughout the state of North Carolina. We analyzed results using descriptive statistics. RESULTS: We received 530 returned questionnaires (76% response rate). Of the 43% (n=226) who reported performing HBPM, 68% purchased their monitor from a pharmacy or department store; the remaining purchased their monitor elsewhere or received it as a gift. Approximately 19% [95% confidence interval (CI): 13.6-23.9] check their BP every day or almost every day; 26% (95% CI: 20.5-32.2) check their BP a few times per week; and 29% (95% CI: 3.0-35.0) check their BP a few times per month. For nearly one-third, their primary reason for using HBPM was because their doctor recommended it. Over one-half said they used HBPM because they were 'just interested in knowing' their BP. The majority (70%; 95% CI: 64.4-76.4) indicated that they did not provide a written report of BP readings to their doctor. Less than one-third (29%, 95% CI: 22.9-34.9) has had their monitor checked by a doctor or nurse. CONCLUSION: Most patients with hypertension using HBPM do so because of a doctor's recommendation or a simple desire to know their BP. The majority of those performing home measurements do so at least a few times per month. Most do not provide their doctor with a written report of measurements, and most have not had their monitor checked.


Subject(s)
Blood Pressure Determination/psychology , Health Knowledge, Attitudes, Practice , Self Care/psychology , Adult , Aged , Cross-Sectional Studies , Female , Health Surveys , Humans , Hypertension/diagnosis , Male , Middle Aged
17.
Jt Comm J Qual Patient Saf ; 34(12): 743-7, 2008 Dec.
Article in English | MEDLINE | ID: mdl-19119728

ABSTRACT

Outcomes, including reductions in codes per 1,000 discharges, failure-to-rescue rates, and medical-surgical mortalities and improvement in staff satisfaction, were all indicative of the efficacy of the APN-model RRT. Future studies might compare these outcomes with those of other team models.


Subject(s)
Emergency Service, Hospital/organization & administration , Heart Arrest/therapy , Hospitals, Teaching/organization & administration , Models, Nursing , Clinical Protocols , Humans , Staff Development/organization & administration
18.
Cell Commun Adhes ; 13(1-2): 41-54, 2006.
Article in English | MEDLINE | ID: mdl-16613779

ABSTRACT

Gap-junctional coupling among neurons is subject to regulation by a number of neurotransmitters including nitric oxide. We studied the mechanisms by which NO regulates coupling in cells expressing Cx35, a connexin expressed in neurons throughout the central nervous system. NO donors caused potent uncoupling of HeLa cells stably transfected with Cx35. This effect was mimicked by Bay 21-4272, an activator of guanylyl cyclase. A pharmacological analysis indicated that NO-induced uncoupling involved both PKG-dependent and PKG-independent pathways. PKA was involved in both pathways, suggesting that PKG-dependent uncoupling may be indirect. In vitro, PKG phosphorylated Cx35 at three sites: Ser110, Ser276, and Ser289. A mutational analysis indicated that phosphorylation on Ser110 and Ser276, sites previously shown also to be phosphorylated by PKA, had a significant influence on regulation. Ser289 phosphorylation had very limited effects. We conclude that NO can regulate coupling through Cx35 and that regulation is indirect in HeLa cells.


Subject(s)
Connexins/metabolism , Cyclic GMP-Dependent Protein Kinases/metabolism , Cyclic GMP/metabolism , Eye Proteins/metabolism , Gap Junctions/metabolism , Nitric Oxide/metabolism , Cell Communication , Cyclic AMP-Dependent Protein Kinases/metabolism , Cyclic GMP/pharmacology , Gap Junctions/drug effects , Guanylate Cyclase/metabolism , HeLa Cells , Humans , Models, Biological , Neurons/metabolism , Nitric Oxide/pharmacology , Patch-Clamp Techniques , Phosphorylation , Serine/metabolism
19.
Biochem Biophys Res Commun ; 335(4): 1191-8, 2005 Oct 07.
Article in English | MEDLINE | ID: mdl-16112650

ABSTRACT

We examined the interactions of calmodulin with neuronal gap junction proteins connexin35 (Cx35) from perch, its mouse homologue Cx36, and the related perch Cx34.7 using surface plasmon resonance. Calmodulin bound to the C-terminal domains of all three connexins with rapid kinetics in a concentration- and Ca2+-dependent manner. Dissociation was also very rapid. K(d)'s for calmodulin binding at a high-affinity site ranged from 11 to 72 nM, and K(1/2)'s for Ca2+ were between 3 and 5 microM. No binding to the intracellular loops was observed. Binding competition experiments with synthetic peptides mapped the calmodulin binding site to a 10-30 amino acid segment at the beginning of the C-terminal domain of Cx36. The micromolar K(1/2)'s and rapid on and off rates suggest that this interaction may change dynamically in neurons, and may occur transiently when Ca2+ is elevated to a level that would occur in the near vicinity of an activated synapse.


Subject(s)
Calcium/chemistry , Calmodulin/chemistry , Connexins/chemistry , Eye Proteins/chemistry , Fish Proteins/chemistry , Neurons/chemistry , Animals , Binding Sites , Mice , Perches , Protein Binding , Gap Junction delta-2 Protein
20.
Brain Res Mol Brain Res ; 135(1-2): 1-11, 2005 Apr 27.
Article in English | MEDLINE | ID: mdl-15857663

ABSTRACT

Connexin 35 (Cx35) is a major component of electrical synapses in the central nervous system. Many gap junctions containing Cx35 are regulated by dopamine receptor pathways that involve protein kinase A (PKA). To study the mechanism of PKA regulation, we analyzed direct phosphorylation of Cx35 by PKA in vitro and studied the regulation of neurobiotin tracer coupling in HeLa cells expressing Cx35 or Cx35 mutants that lack phosphorylation sites. In Cx35-transfected cells, application of the PKA activator Sp-8-cpt-cAMPS caused a significant decline in coupling, while a PKA inhibitor, Rp-8-cpt-cAMPS, significantly increased tracer coupling. In vitro phosphorylation and mutagenic analysis showed that PKA phosphorylates Cx35 directly at two major sites, Ser110 in the intracellular loop and Ser276 in the carboxyl terminus. In addition, a minor phosphorylation site in the C-terminus was identified by truncation of the last 7 amino acids at Ser298. The mutations Ser110Ala or Ser276Ala significantly reduced regulation of coupling by the PKA activator while a combination of the two eliminated regulation. Truncation at Ser298 reversed the regulation such that the PKA activator significantly increased and the PKA inhibitor significantly decreased coupling. The activation was eliminated in the S110A, S276A, S298ter triple mutant. We conclude that PKA regulates Cx35 coupling in a complex manner that requires both major phosphorylation sites. Furthermore, the tip of the C-terminus acts as a "switch" that determines whether phosphorylation will inhibit or enhance coupling. Reliance on the combined states of three sites provides fine control over the degree of coupling through Cx35 gap junctions.


Subject(s)
Connexins/metabolism , Cyclic AMP-Dependent Protein Kinases/metabolism , Cyclic AMP/analogs & derivatives , Gap Junctions/metabolism , Alanine/genetics , Amino Acid Sequence , Animals , Connexins/chemistry , Connexins/genetics , Cyclic AMP/pharmacology , Cyclic AMP-Dependent Protein Kinases/chemistry , Cyclic AMP-Dependent Protein Kinases/genetics , Enzyme Inhibitors/pharmacology , Gene Expression Regulation/drug effects , HeLa Cells , Humans , Immunohistochemistry/methods , Mice , Models, Biological , Mutagenesis/physiology , Mutation , Perches , Phosphorylation/drug effects , RNA, Messenger/biosynthesis , Recombinant Fusion Proteins/biosynthesis , Recombinant Fusion Proteins/metabolism , Reverse Transcriptase Polymerase Chain Reaction/methods , Sequence Alignment , Serine/genetics , Serine/metabolism , Skates, Fish , Transfection/methods
SELECTION OF CITATIONS
SEARCH DETAIL
...