The Role of the Pleckstrin Homology Domain in Membrane Targeting and Activation of Phospholipase Cβ1

Current studies involve an investigation of the role of the pleckstrin homology (PH) domain in membrane targeting and activation of phospholipase Cbeta(1) (PLCbeta(1)). Here we report studies on the membrane localization of the isolated PH domain from the amino terminus of PLCbeta(1) (PLCbeta(1)-PH) using fluorescence microscopy of a green fluorescent protein fusion protein. Whereas PLCbeta(1)-PH does not localize to the plasma membrane in serum-starved cells, it undergoes a rapid but transient migration to the plasma membrane upon stimulation of cells with serum or lysophosphatidic acid (LPA). Regulation of the plasma membrane localization of PLCbeta(1)-PH by phosphoinositides was also investigated. PLCbeta(1)-PH was found to bind phosphatidylinositol 3-phosphate most strongly, whereas other phosphoinositides were bound with lower affinity. The plasma membrane localization of PLCbeta(1)-PH induced by serum and LPA was blocked by wortmannin pretreatment and by LY294002. In parallel, activation of PLCbeta by LPA was inhibited by wortmannin, by LY294002, or by the overexpression of PLCbeta(1)-PH. Microinjection of betagamma subunits of G proteins in serum-starved cells induced the translocation of PLCbeta(1)-PH to the plasma membrane. These results demonstrate that a cooperative mechanism involving phosphatidylinositol 3-phosphate and the Gbetagamma subunit regulates the plasma membrane localization and activation of PLCbeta(1)-PH

Differentiation-dependent lysine 4 acetylation enhances MEF2C binding to DNA in skeletal muscle cells

Myocyte enhancer factor 2 (MEF2) proteins play a key role in promoting the expression of muscle-specific genes in differentiated muscle cells. MEF2 activity is regulated by the association with several transcriptional co-factors and by post-translational modifications. In the present report, we provide evidence for a novel regulatory mechanism of MEF2C activity, which occurs at the onset of skeletal muscle differentiation and is based on Lys4 acetylation. This covalent modification results in the enhancement of MEF2C binding to DNA and chromatin. In particular, we report that the kinetic parameters of MEF2/DNA association change substantially upon induction of differentiation to give a more stable complex and that this effect is mediated by Lys4 acetylation. We also show that Lys4 acetylation plays a prominent role in the p300-dependent activation of MEF2C

Low-density lipoprotein (LDL) receptor/transferrin fusion protein: in vivoproduction and functional evaluation as a potential therapeutic tool forlowering plasma LDL cholesterol.

A soluble form of human low-density lipoprotein receptor (LDL-R) fused in frame with rabbit transferrin (LDL-Rs(hu)/Tf(rab)) is assessed in vivo as a therapeutic tool for lowering plasma LDL cholesterol. The cDNA encoding LDL-Rs(hu)/Tf(rab) is expressed in mice, using a hydrodynamics-based gene transfer procedure. The transgene is transcribed in the liver of transduced animals and the corresponding protein is secreted into the bloodstream. Circulating LDL-Rs(hu)/Tf(rab) binds LDL specifically, thus indicating that it is correctly processed through the cellular compartments in vivo. More importantly, the expression of LDL-Rs(hu)/Tf(rab) allows the removal of injected human (125)I-labeled LDL ((123)I-LDL) from the bloodstream of transduced CD1 mice, which show faster LDL plasma clearance, anticipating by approximately 90 min the same clearance value observed in control animals. A similar effect is observed in transduced LDL-R(-/-) mice, in which the clearance of injected human LDL depends solely on the presence of circulating LDL-Rs(hu) /Tf(rab). In these animals the extent of plasma LDL clearance is directly related to the concentration of LDL-Rs(hu)/Tf(rab) in the blood. Finally, LDL-Rs(hu)/Tf(rab) does not alter the pattern of LDL organ distribution: in transduced animals, as well as in control animals, liver and bladder are the predominantly labeled organs after (123)I-LDL injection. However, LDL-Rs(hu)/Tf(rab) has a quantitative effect on LDL tissue deposition: in treated animals LDL-Rs(hu)/Tf(rab) determines an increase in radioactivity in the liver at early times after (123)I-LDL injection and a progressive labeling of the bladder, starting 20 min after injection

Changes in Cancer Patients' and Caregivers' Disease Perceptions While Receiving Early Palliative Care: A Qualitative and Quantitative Analysis

BACKGROUND: Little is known about the underlying mechanisms through which early palliative care (EPC) improves multiple outcomes in patients with cancer and their caregivers. The aim of this study was to qualitatively and quantitatively analyze patients’ and caregivers’ thoughts and emotional and cognitive perceptions about the disease prior to and during the EPC intervention, and in the end of life, following the exposure to EPC. MATERIALS AND METHODS: Seventy‐seven patients with advanced cancer and 48 caregivers from two cancer centers participated in semistructured interviews. Their reports were qualitatively and quantitatively analyzed by the means of the grounded theory and a text‐analysis program. RESULTS: Participants reported their past as overwhelmed by unmanaged symptoms, with detrimental physical and psychosocial consequences. The EPC intervention allowed a prompt resolution of symptoms and of their consequences and empowerment, an appreciation of its multidimensional approach, its focus on the person and its environment, and the need for EPC for oncologic populations. Patients reported that conversations with the EPC team increased their acceptance of end of life and their expectation of a painless future. Quantitative analysis revealed higher use of Negative Affects (p < .001) and Biological Processes words (p < .001) when discussing the past; Agency words when discussing the present (p < .001); Positive Affects (p < .001), Optimism (p = .002), and Insight Thinking words (p < .001) when discussing the present and the future; and Anxiety (p = .002) and Sadness words (p = .003) when discussing the future. CONCLUSION: Overall, participants perceived EPC to be beneficial. Our findings suggest that emotional and cognitive processes centered on communication underlie the benefits experienced by participants on EPC. IMPLICATIONS FOR PRACTICE: By qualitative and quantitative analyses of the emotional and cognitive perceptions of cancer patients and their caregivers about their experiences before and during EPC interventions, this study may help physicians/nurses to focus on the disease perception by patients/caregivers and the benefits of EPC, as a standard practice. The analysis of words used by patients/caregivers provides a proxy for their psychological condition and support in tailoring an EPC intervention, based on individual needs. This study highlights that the relationship of the triad EPC team/patients/caregivers may rise as a therapeutic tool, allowing increasing awareness and progressive acceptance of the idea of death