HIV Replication Enhances Production of Free Fatty Acids, Low Density Lipoproteins and Many Key Proteins Involved in Lipid Metabolism: A Proteomics Study

BACKGROUND: HIV-infected patients develop multiple metabolic abnormalities including insulin resistance, lipodystrophy and dyslipidemia. Although progression of these disorders has been associated with the use of various protease inhibitors and other antiretroviral drugs, HIV-infected individuals who have not received these treatments also develop lipid abnormalities albeit to a lesser extent. How HIV alters lipid metabolism in an infected cell and what molecular changes are affected through protein interaction pathways are not well-understood. RESULTS: Since many genetic, epigenetic, dietary and other factors influence lipid metabolism in vivo, we have chosen to study genome-wide changes in the proteomes of a human T-cell line before and after HIV infection in order to circumvent computational problems associated with multiple variables. Four separate experiments were conducted including one that compared 14 different time points over a period of >3 months. By subtractive analyses of protein profiles overtime, several hundred differentially expressed proteins were identified in HIV-infected cells by mass spectrometry and each protein was scrutinized for its biological functions by using various bioinformatics programs. Herein, we report 18 HIV-modulated proteins and their interaction pathways that enhance fatty acid synthesis, increase low density lipoproteins (triglycerides), dysregulate lipid transport, oxidize lipids, and alter cellular lipid metabolism. CONCLUSIONS: We conclude that HIV replication alone (i.e. without any influence of antiviral drugs, or other human genetic factors), can induce novel cellular enzymes and proteins that are significantly associated with biologically relevant processes involved in lipid synthesis, transport and metabolism (p = <0.0002-0.01). Translational and clinical studies on the newly discovered proteins may now shed light on how some of these proteins may be useful for early diagnosis of individuals who might be at high risk for developing lipid-related disorders. The target proteins could then be used for future studies in the development of inhibitors for preventing lipid-metabolic anomalies. This is the first direct evidence that HIV-modulates production of proteins that are significantly involved in disrupting the normal lipid-metabolic pathways

Protein kinase C and cardiac dysfunction: a review

Heart failure (HF) is a physiological state in which cardiac output is insufficient to meet the needs of the body. It is a clinical syndrome characterized by impaired ability of the left ventricle to either fill or eject blood efficiently. HF is a disease of multiple aetiologies leading to progressive cardiac dysfunction and it is the leading cause of deaths in both developed and developing countries. HF is responsible for about 73,000 deaths in the UK each year. In the USA, HF affects 5.8 million people and 550,000 new cases are diagnosed annually. Cardiac remodelling (CD), which plays an important role in pathogenesis of HF, is viewed as stress response to an index event such as myocardial ischaemia or imposition of mechanical load leading to a series of structural and functional changes in the viable myocardium. Protein kinase C (PKC) isozymes are a family of serine/threonine kinases. PKC is a central enzyme in the regulation of growth, hypertrophy, and mediators of signal transduction pathways. In response to circulating hormones, activation of PKC triggers a multitude of intracellular events influencing multiple physiological processes in the heart, including heart rate, contraction, and relaxation. Recent research implicates PKC activation in the pathophysiology of a number of cardiovascular disease states. Few reports are available that examine PKC in normal and diseased human hearts. This review describes the structure, functions, and distribution of PKCs in the healthy and diseased heart with emphasis on the human heart and, also importantly, their regulation in heart failure

Expression Analysis of Recombinant Lysyl Oxidase (LOX) in Myofibroblastlike Cells

International audienceLysyl oxidase (LOX), originally known as the enzyme required for initiation of covalent cross-linking in collagens and elastin, is now known to be a member of a family of genetically related proteins. LOX, or a related protein, has also been localized intracellularly, both in association with the cytoskeleton and in the cell nucleus. To determine the structural requirements for secretion, maturation, and nuclear location of LOX in a cellular context, we have devised an homologous cell model for expression of the recombinant protein. Murine recombinant LOX was expressed in 3T6-5 myofibroblast-like cells as a 51-kD precursor, which was observed in the cytoplasm but not in the nucleus. To investigate whether potential alternative translation initiation sites were involved in specifying a nuclear form of LOX, constructs mutated or deleted for ATG(+1) were used, but alternative initiation at CTG(-315) or ATG(+418) did not lead to the expression of intranuclear forms. Residues 23 to 157 of the proregion were essential for export of the precursor, while mutation of the putative site for maturation by procollagen C-proteinase abolished processing to the mature form of the enzyme. Cross-linking of collagen, as measured by pyridinoline analysis, increased twofold with the recombinant cells, compared to non-transfected controls. This shows the specific contribution of LOX, as opposed to other genetic forms of the enzyme, to cross-linking in a cellular context.Lysyl oxidase (LOX), originally known as the enzyme required for initiation of covalent cross-linking in collagens and elastin, is now known to be a member of a family of genetically related proteins. LOX, or a related protein, has also been localized intracellularly, both in association with the cytoskeleton and in the cell nucleus. To determine the structural requirements for secretion, maturation, and nuclear location of LOX in a cellular context, we have devised an homologous cell model for expression of the recombinant protein. Murine recombinant LOX was expressed in 3T6-5 myofibroblast-like cells as a 51-kD precursor, which was observed in the cytoplasm but not in the nucleus. To investigate whether potential alternative translation initiation sites were involved in specifying a nuclear form of LOX, constructs mutated or deleted for ATG(+1) were used, but alternative initiation at CTG(-315) or ATG(+418) did not lead to the expression of intranuclear forms. Residues 23 to 157 of the proregion were essential for export of the precursor, while mutation of the putative site for maturation by procollagen C-proteinase abolished processing to the mature form of the enzyme. Cross-linking of collagen, as measured by pyridinoline analysis, increased twofold with the recombinant cells, compared to non-transfected controls. This shows the specific contribution of LOX, as opposed to other genetic forms of the enzyme, to cross-linking in a cellular context