A conserved domain for glycogen binding in protein phosphatase-1 targeting subunits

AbstractThe skeletal muscle glycogen-binding subunit (GM) of protein phosphatase-1 (PP1) is the founding member of a family of proteins that tether the PP1 catalytic subunit (PP1C) to glycogen and promote the dephosphorylation of glycogen synthase. A hydrophobic sequence (called here the VFV motif) is conserved among GM, the liver subunit GL, and the widely expressed subunits, PTG, R5 and U5. This study analyzed the role of this VFV motif in binding to glycogen and PP1C. Glutathione S-transferase (GST) fusions with the N-terminal domain of GM (GST-GM(1–240)) and with the full length R5 protein (GST-R5) both bound to glycogen in a co-sedimentation assay. In contrast, GST itself did not bind to glycogen. A single residue substitution in GST-GM(1–240), F155A, reduced glycogen binding by 40%. Double residue substitutions V150A/F155A and F155A/V159A resulted in greater reductions (60–70%) in glycogen binding, showing these hydrophobic residues influenced the protein-glycogen interaction. The wild type and V150A/F155A fusion proteins were digested by trypsin into the same sized fragments at the same rate. Furthermore, the wild type and mutated GST-GM proteins as well as GST-R5 bound equivalent amounts of PP1C, in either pull-down or far-Western assays. These results demonstrated retention of overall tertiary structure by the mutated fusion proteins, and indicated that glycogen and PP1C binding are independent of one another. A 68 residue segment of R5 encompassing the VFV motif was sufficient to produce glycogen binding when fused to GST. This motif, that is in bacterial and fungal starch metabolizing enzymes, probably has been conserved during evolution as a functional domain for binding glycogen and starch

Binding to Na(+) /H(+) exchanger regulatory factor 2 (NHERF2) affects trafficking and function of the enteropathogenic Escherichia coli type III secretion system effectors Map, EspI and NleH.

Enteropathogenic Escherichia coli (EPEC) strains are diarrhoeal pathogens that use a type III secretion system to translocate effector proteins into host cells in order to colonize and multiply in the human gut. Map, EspI and NleH1 are conserved EPEC effectors that possess a C-terminal class I PSD-95/Disc Large/ZO-1 (PDZ)-binding motif. Using a PDZ array screen we identified Na(+)/H(+) exchanger regulatory factor 2 (NHERF2), a scaffold protein involved in tethering and recycling ion channels in polarized epithelia that contains two PDZ domains, as a common target of Map, EspI and NleH1. Using recombinant proteins and co-immunoprecipitation we confirmed that NHERF2 binds each of the effectors. We generated a HeLa cell line stably expressing HA-tagged NHERF2 and found that Map, EspI and NleH1 colocalize and interact with intracellular NHERF2 via their C-terminal PDZ-binding motif. Overexpression of NHERF2 enhanced the formation and persistence of Map-induced filopodia, accelerated the trafficking of EspI to the Golgi and diminished the anti-apoptotic activity of NleH1. The binding of multiple T3SS effectors to a single scaffold protein is unique. Our data suggest that NHERF2 may act as a plasma membrane sorting site, providing a novel regulatory mechanism to control the intracellular spatial and temporal effector protein activity

Relationship between Medication Use and Cardiovascular Disease Health Outcomes in the Jackson Heart Study

Even though some medications have the potential to slow the progress of atherosclerosis and development of CVD, there are many at-risk individuals who continue to resist the benefits that are available by not following the advice of medical professionals. Non-adherence to prescribed drug regimens is a pervasive medical problem that negatively affects treatment outcomes. Information from standardized interviews of 5301 African Americans participating in the Jackson Heart Study was examined to determine the association between demographic parameters, behavior including adherence to prescribed medical regimens, and health outcomes. Data were also collected at Annual Follow-Up and Surveillance visits. During the two weeks prior to the examination visit, almost 52% of the participants reported taking blood pressure medication, 14% took cholesterol medication, 16% took medication for diabetes, and 19% took blood thinning medication. Of those who did not take the prescribed medications, the reasons given were the following: 47% were in a hurry, too busy, or forgot to take medications; 23% were trying to do without medications; 18% had no money to purchase medications; 19% indicated that the medications made them feel bad; 17% felt that they could not carry out daily functions when taking medications. The African American population can benefit from heightened awareness of the risk factors that are associated with CVD and the benefits of following a prescribed treatment regimen. Unacceptable secondary effects of prescribed medication comprised an important cause of non-compliance. Encouragement of this population to communicate with their healthcare providers to ensure that medication regimens are better tolerated could increase compliance and improve health outcomes

Cost-effectiveness of initiating extrafine- or standard size-particle inhaled corticosteroid for asthma in two health-care systems: a retrospective matched cohort study

Data acquisition and analyses were funded by Teva Pharmaceuticals