E. Nicolas et al., IN-VIVO REGULATION OF THE I-KAPPA-B HOMOLOG CACTUS DURING THE IMMUNE-RESPONSE OF DROSOPHILA, The Journal of biological chemistry, 273(17), 1998, pp. 10463-10469
The dorsoventral regulatory gene pathway (spatzlel Toll/cactus) contro
ls the expression of several antimicrobial genes during the immune res
ponse of Drosophila. This regulatory cascade shows striking similariti
es with the cytokine-induced activation cascade of NF-kappa B during t
he inflammatory response in mammals. Here, we have studied the regulat
ion of the I kappa B homologue Cactus in the fat body during the immun
e response. We observe that the cactus gene is up-regulated in respons
e to immune challenge. Interestingly, the expression of the cactus gen
e is controlled by the spatzle/Toll/cactus gene pathway, indicating th
at the cactus gene is auto-regulated. We also show that two Cactus iso
forms are expressed in the cytoplasm of fat body cells and that they a
re rapidly degraded and resynthesized after immune challenge. This deg
radation is also dependent on the Toll signaling pathway. Altogether,
our results underline the striking similarities between the regulation
of I kappa B and cactus during the immune response.