Signal transduction in hepatic stellate cells.

Hepatic stellate cells (HSC) are presently regarded as one of the key cell types involved in the progression of liver fibrosis and in the related pathophysiological and clinical complications. Following acute or chronic liver tissue damage, HSC undergo a process of activation towards a phenotype characterised by increased proliferation, motility, contractility and synthesis of extracellular matrix (ECM) components. Several factors have been shown to play a key role in the promotion of the full-blown picture of activated HSC. These include extensive changes in the composition and organisation of the ECM, the secretion of several growth factors, cytokines, chemokines, products of oxidative stress and other soluble factors. It is evident that each cellular response to extracellular stimuli must be framed in a scenario where different forces modulate one another and result in a prevalent biological effect. Along these lines, the identification and characterisation of intracellular signalling pathways activated by different stimuli in HSC represent a mandatory step. In this review article we have made an attempt to summarise recent acquisitions to our knowledge of the involvement of different intracellular signalling pathways in key aspects of HSC biology.