Lysosomal degradation of RhoH protein upon antigen receptor activation in T but not B cells

RhoH is a member of the Rho (ras homologous) GTPase family, yet it lacks GTPase activity and thus remains in its active conformation. Unlike other Rho GTPases, the RhoH gene transcript is restricted to hematopoietic cells and RhoH was shown to be required for adequate T-cell activation through the TCR. Here, we demonstrate that both blood T and B cells, but not neutrophils or monocytes, express RhoH protein under physiological conditions. Upon TCR complex activation, RhoH was degraded in lysosomes of primary and Jurkat T cells. Pharmacologic activation of T cells distal to the TCR complex had no effect on RhoH protein levels suggesting that early events during T-cell activation are required for RhoH protein degradation. In contrast to T cells, activation of the BCR in blood B cells was not associated with changes in RhoH levels. These data suggest that RhoH function might be regulated by lysosomal degradation of RhoH protein following TCR complex but not BCR activation. This newly discovered regulatory pathway of RhoH expression might limit TCR signaling and subsequent T-cell activation upon Ag contact.

Monitoring and Assessment of Desertification and Land Degradation: Knowledge Management, Institutions and Economics: White Paper of the DSD Working Group 3

The White Paper is a review of leading scientific knowledge on the role of knowledge management, institutions and economics in monitoring and assessment of land degradation and desertification. It provides key recommendations for more effective policies and actions for combating desertification both withn the UNCCD and beyond. This White Paper is the result of an international collaboration and consultation led jointly by the Association of DesertNet International and the United Nations University - Institute for Water, Environment and Health (UNU-INWEH), of the Dryland Science for Development Consortium (DSD). The findings were presented at the First UNCCD Scientific Conference held during the COP-9 in Buenos Aires, 2009.