Small stress protein Hsp27 accumulation during dopamine-mediated differentiation of rat olfactory neurons counteracts apoptosis

The small stress protein Hsp27 is expressed during mammalian neural develop ment, We have analyzed the role of this protein in immortalized rat olfacto ry neuroblasts, In the presence of dopamine a fraction of these cells diffe rentiate into neurons while the remaining cells undergo apoptosis, We repor t here that the dopamine induced differentiation and apoptosis are associat ed with a transient and specific accumulation of Hsp27, Moreover, transfect ion experiments have shown that Hsp27 overexpression drastically decreases the fraction of cells undergoing apoptosis, In contrast, reduction of the e ndogenous level of Hsp27 led to abortion of differentiation and, therefore, drastically increased the number of apoptotic cells, Furthermore, in the n ormal cell population we show that Hsp27 accumulation takes place on ly in differentiating cells that were not undergoing apoptosis, We therefore conc lude that Hsp27 may represent a key protein that controls the decision of o lfactory precursor cells to undergo either differentiation or cell death.