MICROBIOLOGY: Signaling Disease

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Science  10 Aug 2001:
Vol. 293, Issue 5532, pp. 1015a
DOI: 10.1126/science.293.5532.1015a

Theileria spp. are intracellular protozoan parasites that cause an economically damaging disease in African cattle, East Coast fever. They reversibly transform leukocytes by interfering with several host cell signaling pathways in the absence of antigen or exogenous growth factors.

Theileria are known to induce activation of the transcription factor NF-κB. This enables the protozoan to block initiation of apoptosis (programmed cell death) that would otherwise be provoked by inappropriate cell proliferation. The activation of NF-κB was thought to be routed via the second messenger phosphoinositide 3-kinase (PI3-K) and the serine-threonine kinase Akt/PKB, but Heussler et al. show that although Akt/PKB is indeed activated, it does not appear to be linked to the NF-κB pathway. It seems that PI3-K is activated indirectly via an adhesion molecule on the transformed cells, resulting in the stimulation of Akt/PKB; instead of protecting against apoptosis, Akt/PKB appears to have a more directly aggressive role in stimulating the proliferation of Theileria-transformed T cells. — CA

Cell. Microbiol. 3, 537 (2001).

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