Regulation of expression and signalling modulator function of mammalian tribbles is cell-type specific.

The constant need to respond to changes in the environment is a common feature for all life forms. During evolution, a number of intracellular signal processing systems have evolved to fulfill this requirement. One of the most ancient such systems is the mitogen activated protein kinase (MAPK) signalling network, shared by all eukaryotes. Activation of MAPKs is key to regulation of mitosis and in cellular responses to stress or hormones, for instance. In addition, activity of this signalling system is essential during embryonic development. However, many aspects of MAPK mediated responses are strongly cell-type specific. A family of proteins, called tribbles have recently been described as novel regulators of MAPK function. Our group has previously shown that alterations in tribbles levels lead to profound changes in the activation of the various MAPKs. However, little is known about the cell-type specific aspects of regulation of tribbles expression. Here, we report that expression of all three members of the human tribbles family is dynamically controlled in response to inflammatory stimulation. This regulation, however, is strongly cell-type dependent. Our observations suggest regulation of tribbles expression may play an important role in the cell-type specific cellular responses, mediated by the MAPK network.