Overview of Alterations in Cell Signaling

Cellular homeostasis involves the orchestration of complex biochemical events that ensure survival and preservation of differentiated functions. Toxic injury often alters cellular programming in ways that disrupt cellular signaling pathways and culminate in altered states that may or may not be consistent with cellular functions. For simplicity, this article has been organized to provide an overview of the major components of signal transduction: the specific signals, the sensors, and their corresponding signaling pathways. How toxic chemicals impinge on each of these components will be discussed in general terms with some references to the specifics covered in other articles provided when appropriate. The goal is to describe the signaling pathways that are often affected by carcinogenic compounds, specifically tumor promoters. The basic framework of the signal transduction cascade will be investigated. In subsequent articles, specific examples of xenobiotic alterations in signal transduction will be portrayed, as will the ultimate toxic responses of altered cell cycle control and apoptosis.