T cell receptor signaling pathway is overexpressed in CD4 + T cells from HAM/TSP individuals

ABSTRACT Human T-lymphotropic virus type 1 (HTLV-1) is a human retrovirus related to the chronic neuroinflammatory disease HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). CD4+ T cells activation appears to play a key role on HTLV-1 infection. Here we investigated the expression of genes associated to T cell activation CD3e molecule, epsilon (CD3?), lymphocyte-specific protein tyrosine kinase (LCK), vav 1 guanine nucleotide exchange factor (VAV1), and zeta-chain (TCR) associated protein kinase 70 kDa (ZAP70) on T lymphocytes of HTLV-1-infected individuals and compared to healthy uninfected individuals (CT). We observed that CD3?, LCK, ZAP70, and VAV1 gene expression were increased in CD4+ T cells from HAM/TSP group compared to HTLV-1 asymptomatic patients (HAC). Moreover, ZAP70 and VAV1 were also upregulated in HAM/TSP compared to CT group. We detected a positive correlation among all these genes. We also observed that CD3?, LCK, and VAV1 genes had a positive correlation with the proviral load (PVL) and Tax expression. These results suggest that PVL and Tax protein could drive CD3?, LCK, and VAV1 gene expression in CD4+ T cells, and these genes function on a synchronized way on the CD4+ T cell activation. The elucidation of the mechanisms underlying T cell receptor signaling pathway is of considerable interest and might lead to new insights into the mechanism of HAM/TSP.

T cell receptor signaling pathway is overexpressed in CD4(+) T cells from HAM/TSP individuals.

Human T-lymphotropic virus type 1 (HTLV-1) is a human retrovirus related to the chronic neuroinflammatory disease HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). CD4(+) T cells activation appears to play a key role on HTLV-1 infection. Here we investigated the expression of genes associated to T cell activation CD3e molecule, epsilon (CD3ɛ), lymphocyte-specific protein tyrosine kinase (LCK), vav 1 guanine nucleotide exchange factor (VAV1), and zeta-chain (TCR) associated protein kinase 70kDa (ZAP70) on T lymphocytes of HTLV-1-infected individuals and compared to healthy uninfected individuals (CT). We observed that CD3ɛ, LCK, ZAP70, and VAV1 gene expression were increased in CD4(+) T cells from HAM/TSP group compared to HTLV-1 asymptomatic patients (HAC). Moreover, ZAP70 and VAV1 were also upregulated in HAM/TSP compared to CT group. We detected a positive correlation among all these genes. We also observed that CD3ɛ, LCK, and VAV1 genes had a positive correlation with the proviral load (PVL) and Tax expression. These results suggest that PVL and Tax protein could drive CD3ɛ, LCK, and VAV1 gene expression in CD4(+) T cells, and these genes function on a synchronized way on the CD4(+) T cell activation. The elucidation of the mechanisms underlying T cell receptor signaling pathway is of considerable interest and might lead to new insights into the mechanism of HAM/TSP.

Efecto de la proteína E2 del virus de hepatitis C sobre la activación de células NK / Effect of E2 protein of hepatitis C virus on the activation of NK cells

En estudios previos, se ha descrito un disminución de la activación y actividad citotóxica de las células NK en los pacientes infectados con hepatitis C; sin embargo, se desconoce el mecanismo por el cual éste fenómeno ocurre. En el presente reporte se estudió el efecto de la proteína E2 de la envoltura del virus o de la estimulación de su receptor con el anticuerpo anti-CD81 sobre la fosforilación de tirosinas, serinas, las enzimas: proteína quinasa C y fosfoinositol 3 quinasa, el factor de transcrición Nfkb y el intercambiador de nueclotidos VAV de células NK de controles normales estimulados con anti-CD16. Ambos, la proteína E2 y anti-CD81, combinado o por separado inducen una disminución de la fosforilación de tirosinas y serinas, así como una marcada disminución de la fosforilación de PKC, NFkB, PI3K y en menor grado VAV. Se concluye que la proteína E2 sola y en conjunto con anti-CD81 inducen señales inhibitorias responsables de la disminución en la activación de las células NK de pacientes infectados por el VHC y que éste fenómeno puede ser responsable de la cronicidad que se reporta en dicha enfermedad

The decrease in NK cell activation and cytotoxic activity in patients infected with hepatitis C virus has been described; however, the mechanism by whcih this phenomenon occurs is not known. In the present report, the effect of the E2 protein of the virus envelope or the stimulation of its receptor CD81 with the antibody anti-CD81 on the phosphorylation of tyrosines, serine, the enzymes protein kinase C, phosphoinositol kinase 3 (PI3K), the transcription factor NfkB and the nucleotide exchange protein VAV was assessed in NK cells from normal controls stimulated with anti-CD16. Both the protein E2 and anti-CD81 by themselves or combined, generated a decrease in tyrosine, serine, and a marked decrease in the phosphorylation of PKC, NfkB, PI3k and in less extent in VAV. It is concluded that the E2 protein alone and combined with anti-CD81 induce inhibitory signals responseible for the decrease in the activation of NK cells of infected HCV patients and it could be responsible for the chronicity observed in this disease

Regulation of Cbl molecular interactions by the co-receptor molecule CD43 in human T cells.

CD43, one of the most abundant glycoproteins on the T cell surface, has been implicated in selection and maturation of thymocytes and migration, adhesion, and activation of mature T cells. The adapter molecule Cbl has been shown to be a negative regulator of Ras. Furthermore, it may also regulate intracellular signaling through the formation of several multi-molecular complexes. Here we investigated the role of Cbl in the CD43-mediated signaling pathway in human T cells. Unlike T cell receptor signaling, the interaction of the adapter protein Cbl with Vav and phosphatidylinositol 3-kinase, resulting from CD43-specific signals, is independent of Cbl tyrosine phosphorylation, suggesting an alternative mechanism of interaction. CD43 signals induced a Cbl serine phosphorylation-dependent interaction with the tau-isoform of 14-3-3. protein. Protein kinase C-mediated Cbl serine phosphorylation was required for this interaction, because the PKC inhibitor RO-31-8220 prevented it, as well as 14-3-3 dimerization. Moreover, mutation of Cbl serine residues 619, 623, 639, and 642 abolished the interaction between Cbl and 14-3-3. Overexpression of Cbl in Jurkat cells inhibited the CD43-dependent activation of the mitogen-activated protein kinase (MAPK) pathway and AP-1 transcriptional activity, confirming nevertheless a negative role for Cbl in T cell signaling. However, under normal conditions, PKC activation resulting from CD43 engagement was required to activate the MAPK pathway, suggesting that phosphorylation of Cbl on serine residues by PKC and its association with 14-3-3 molecules may play a role in preventing the Cbl inhibitory effect on the Ras-MAPK pathway. These data suggest that by inducing its phosphorylation on serine residues, CD43-mediated signals may regulate the molecular associations and functions of the Cbl adapter protein.