CD4 ligation excludes the Carma1-Bcl10-MALT1 complex from GM1-positive membrane rafts in CD3/CD28 activated T cells.

The antibody 13B8.2, which is directed against the CDR3-like loop on the D1 domain of CD4, induces CD4/ZAP-70 reorganization and ceramide release in membrane rafts. Here, we investigated whether CD4/ZAP-70 compartmentalization could be mediated by an effect of 13B8.

The lipid-modulating effects of a CD4-specific recombinant antibody correlate with ZAP-70 segregation outside membrane rafts.

We previously reported that the anti-tumoral effects of the recombinant IgG(1) antibody 13B8.2, which is directed against the CDR3-like loop on the D1 domain of CD4, are linked to accumulation/retention of CD4 inside membrane rafts, recruitment of signaling molecules of the TCR/CD3 pathway and raft exclusion of the ZAP-70 kinase and its downstream targets Vav-1, PLCγ1 and SLP-76. We thus wanted to assess whether this compartmentalization could be related to a possible effect of 13B8.

PKC zeta mTOR pathway: a new target for rituximab therapy in follicular lymphoma.

Previous studies have documented that, in malignant B cells, rituximab elicits a complex and not yet totally understood signaling network contributing to its antitumor effect. In this context, we investigated the role of protein kinase C zeta (PKCzeta), an atypical PKC isoform, in the cellular response to rituximab. We found that follicular lymphoma cells displayed an increase in PKCzeta expression and activity levels, compared with nonmalignant B cells, and that this enzyme was a critical regulator of the classical MAPK module by stimulating Raf-1 kinase activity.

Re-arrangements of podosome structures are observed when Hck is activated in myeloid cells.

Podosomes are adhesion structures with an extracellular matrix-degrading capacity mostly found in monocyte-derived cells. We have previously shown that the protein tyrosine kinase Hck, a member of the Src family, triggers the de novo formation of podosome rosettes in a lysosome-dependent manner when expressed in its constitutively active form. Hck is specifically expressed in myeloid cells.