Participation of CREB3 transcription factors in cell differentiation models

L. SAMPIERI; M. BISBAL; P. DI GIUSTO; C. ALVAREZ

Sorento

Congreso; The 2018 Golgi meeting: Membrane trafficking in cell organization and homeostasis. 15-19 October 2018 I Sorrento, Italy.; 2018

Federation of European Biochemical Societies (FEBS).

CREB3 family of bZip transcription factors show tissue-specific expression patterns. Although they have been described to participate in cell differentiation in various tissues by regulating the secretory machinery, very little is known about their role in the nervous system. Our goal is to analyze the regulation of the secretory pathway and the participation of CREB3 factors in cell development and differentiation models, specifically in neuronal cells. We are working on two models: PC12 cells, which can differentiate to neuron-like cells upon treatment with NGF, and hippocampal cells in culture obtained from rat embryos. We show that NGF induces a time- dependent increase in protein levels of different markers of the early secretory pathway. Moreover, NGF increases significantly mRNA and protein levels of CREB3L2,while other members of the CREB3 family do not respond the same way. The NGF-induced effect on CREB3L2 is abolished when cells are incubated with U0126 and H89, pharmacological inhibitors of MEK1 and MEK2 MAP kinases and PKA, respectively. Inhibition of CREB3L2 expression by shRNA reduces the number of neurites induced by NGF treatment. Furthermore, immunofluorescences of hippocampal neurons in culture show an increase in the levels of CREB3L2 at different days in vitro (DIV). Changes in other CREB3 members need to be explored in these cells. Taken together, our data suggest that: a) CREB3L2 transcription factor accompanies the differentiation process in neuronal cells; b) increase in CREB3L2 is both MEK/ERK and PKA dependent, proposing a dual regulation of this factor, c) CREB3L2 may contribute to the process of neurite formation in PC12 cells. Further analyses are needed to investigate the molecular mechanisms underlying these changes and to elucidate the specific function of CREB3 family in both models.