TOX 300 Lecture Notes - Lecture 12: Adrenergic Receptor, Nicotinic Acetylcholine Receptor, Ras Subfamily
Document Summary
The nature of the primary cellular dysfunction caused by toxicants depends on the role of the target molecule affected. If target (cid:373)ole(cid:272)ule is i(cid:374)volved i(cid:374) a (cid:272)ell"s i(cid:374)ter(cid:374)al (cid:373)ai(cid:374)te(cid:374)a(cid:374)(cid:272)e, dysfu(cid:374)(cid:272)tio(cid:374) of the molecule can affe(cid:272)t the (cid:272)ell"s a(cid:271)ility to survive. If target molecule is involved in external functions, it can influence the operation of other cells and integrated organ systems. Role of target molecule: cell regulation, dysregulation of gene expression, dysregulation of ongoing cell function, cell maintenance, impaired internal maintenance, impaired external maintenance. 2 key processes in cellular regulation are gene expression and phosphorylation of proteins. May occur at level of transcription, intracellular signal-transduction pathway, and the signaling molecules (their synthesis, storage or release) Chemical messengers (cytokines, hormones, growth factors etc. Pathways are not linear there is cross talk. Converge down on transcription factors is the main target. Increase or decrease mrna production: many are involved balance between mitosis and apoptosis (excessive cell division cancer)