STAT signalling in the mature and aging brain

Activation of the Janus kinases (JAK) and signal transducers and activator of transcription (STAT) proteins in response to specific cytokines and grow th factors has been investigated primarily in cells of non-neuronal origin. More recently, the JAKs and the STATs have also been found to be active in the developing and mature brain, providing evidence for important roles pl ayed by these molecules in the control of neuronal proliferation, survival and differentiation. Nothing, however, is known about their occurrence and role(s) in the aged brain. We, therefore, investigated the presence of Stat 3 and Stat1 in aged-rat brain, and have found that the Stat3 protein was ma rkedly down regulated with respect to adult tissue, while Stat1 remained in variant. We also investigated the potential role of some growth factors in the activation of the JAK/STAT in mature neurons, exposing primary neuronal cells to ciliary neurotrophic factor (CNTF), basic fibroblast growth facto r (bFGF) and epidermal growth factor (EGF). Besides CNTF, which is known to recruit Stat3, we found that Stat3 was also tyrosine phosphorylated by bFG F. These data are indicative of an important role of Stat3 and Stat1 in reg ulating the physiological status of mature neurons. (C) 2000 ISDN. Publishe d by Elsevier Science Ltd. All rights reserved.