Impact of Metabolic Regulators on the Expression of the Obesity Associated Genes FTO and NAMPT in Human Preadipocytes and Adipocytes

FTO and NAMPT/PBEF/visfatin are thought to play a role in obesity but their transcriptional regulation in adipocytes is not fully understood. In this study, we evaluated the transcriptional regulation of FTO and NAMPT in preadipocytes and adipocytes by metabolic regulators.We assessed FTO mRNA expression during human adipocyte differentiation of Simpson-Golabi-Behmel syndrome (SGBS) cells and primary subcutaneous preadipocytes in vitro and evaluated the effect of the metabolic regulators glucose, insulin, dexamethasone, IGF-1 and isoproterenol on FTO and NAMPT mRNA expression in SGBS preadipocytes and adipocytes. FTO mRNA levels were not significantly modulated during adipocyte differentiation. Also, metabolic regulators had no impact on FTO expression in preadipocytes or adipocytes. In SGBS preadipocytes NAMPT expression was more than 3fold induced by dexamethasone and isoproterenol and 1.6fold by dexamethasone in adipocytes. Complete glucose restriction caused an increase in NAMPT mRNA expression by more than 5fold and 1.4fold in SGBS preadipocytes and adipocytes, respectively.FTO mRNA expression is not significantly affected by differentiation or metabolic regulators in human adipocytes. The stimulation of NAMPT expression by dexamethasone, isoproterenol and complete glucose restriction may indicate a regulation of NAMPT by metabolic stress, which was more pronounced in preadipocytes compared to mature adipocytes

Using death to one's advantage: HIV modulation of apoptosis

Infection by human immunodeficiency virus (HIV) is associated with an early immune dysfunction and progressive destruction of CD4+ T lymphocytes. This progressive disappearance of T cells leads to a lack of immune control of HIV replication and to the development of immune deficiency resulting in the increased occurrence of opportunistic infections associated with acquired immune deficiency syndrome (AIDS). The HIV-induced, premature destruction of lymphocytes is associated with the continuous production of HIV viral proteins that modulate apoptotic pathways. The viral proteins, such as Tat, Env, and Nef, are associated with chronic immune activation and the continuous induction of apoptotic factors. Viral protein expression predisposes lymphocytes, particularly CD4+ T cells, CD8+ T cells, and antigen-presenting cells, to evolve into effectors of apoptosis and as a result, to lead to the destruction of healthy, non-infected T cells. Tat and Nef, along with Vpu, can also protect HIV-infected cells from apoptosis by increasing anti-apoptotic proteins and down- regulating cell surface receptors recognized by immune system cells. This review will discuss the validity of the apoptosis hypothesis in HIV disease and the potential mechanism(s) that HIV proteins perform in the progressive T cell depletion observed in AIDS pathogenesis. Originally published Leukemia, Vol. 15, No. 3, Mar 200

Methylation of the SLC6a2 Gene Promoter in Major Depression and Panic Disorder

Reduced function of the noradrenaline transporter (NET) has been demonstrated in patients with major depressive disorder (MDD) and panic disorder. Attempts to explain NET dysfunction in MDD and panic disorder by genetic variation in the NET gene SLC6a2 have been inconclusive. Transcriptional silencing of the SLC6a2 gene may be an alternative mechanism which can lead to NET dysfunction independent of DNA sequence. The objective of this study was to characterise the DNA methylation state of the SLC6a2 gene promoter in patients with MDD and panic disorder. SLC6a2 promoter methylation was also analysed before and after antidepressant treatment. This study was performed with DNA from blood, using bisulphite sequencing and EpiTYPER methylation analyses. Patients with MDD or panic disorder were not found to differ significantly from healthy controls in the pattern of methylation of the SLC6a2 gene promotor. While significant correlations between methylation levels at some CpG sites and physiological measures were identified, overall the variation in DNA methylation between patients was small, and the significance of this variation remains equivocal. No significant changes in SLC6a2 promoter methylation were observed in response to antidepressant treatment. Further in-depth analysis of alternative mechanisms of transcriptional regulation of the SLC6a2 gene in human health and disease would be of value

Human Herpesvirus 7 Infection Induces Profound Cell Cycle Perturbations Coupled to Disregulation of cdc2 and Cyclin B and Polyploidization of CD4+ T Cells

Human herpesvirus 7 (HHV-7) infection of both primary CD4(+) T lymphocytes and SupT1 lymphoblastoid T-cell line induced a progressive accumulation of cells exibiting a gap 2/mitosis (G2/M) and polyploid content coupled to an increased cell size. The expression of both cyclin-dependent kinase cdc2 and cyclin B was increased in HHV-7-infected cells with respect to the uninfected ones. Moreover, the simultaneous flow cytometric analysis of cyclin B and DNA content showed that cyclin B expression was not only increased but also unscheduled with respect to its usual cell cycle pattern. However, the levels of kinase activity associated to cdc2 were decreased in HHV-7-infected cells with respect to uninfected cultures. To elucidate the origin of the enlarged HHV-7-infected cells, extensive electron and confocal microscopy analyses were performed. Membrane fusion events associated to cytoplasmic bridges, which characterize the formation of syncytia, were never observed. On the other hand, analysis of serial sections of the same cells strongly suggested that enlarged HHV-7-infected cells contained a single polylobated nucleus. This was confirmed by flow cytometry analysis performed on nuclei isolated from HHV-7-infected cells, which showed multiple peaks with a DNA content >4n. Taken together, these data indicate that giant cells, which represent the hallmark of in vitro HHV-7 infection, arise from single CD4(+) T cells undergoing a process of polyploidization