c-Fos regulates branching formation in neurons

RODRÍGUEZ, L; FERRERO, GO; CARDOZO-GIZZI, AM; CAPUTTO, BL

Puerto Iguazú

Congreso; 56th International Conference on the Bioscience of Lipids (ICBL); 2015

International Conference on the Bioscience of Lipids

Neuronal differentiation is a complex event where lipid synthesis for membrane biogenesis plays a key role in extension and branching of neuronal processes. As we have previously shown that c-Fos associates to membranes of the endoplasmic reticulum (ER) and activates key enzymes of phospholipid synthesis, it might be associated with the molecular mechanisms that allow the higher rate of membrane genesis required for neuronal differentiation. When c-Fos expression is blocked in primary cultures of rat hippocampal neurons, either using a lentiviral vector that expresses a specific sequence against c-Fos or a specific antibody, differentiation is impaired and no development of axonal processes is observed. Besides, analysis of c-Fos localization by immunofluorescence shows it co-localizing with ER markers in the neuronal soma and mainly forming structures at the branching sites of the neuronal processes. CTP:phosphocholine cytidylyltransferase-β2 (CCTβ2) is an integral enzyme of the ER membranes that has been shown to play an important role in the formation of axon branches. To determine if this enzyme is activated by a c-Fos-dependent mechanism, and taking into consideration that this activation mechanism implies an interaction between both proteins, we initially studied this possible interaction. We observed co-immunoprecipitation of c-Fos with the enzyme and positive FRET values between the tagged proteins, both in the soma (ER) and in the axon of developing neurons, evidencing an interaction between these proteins. These results support the participation of CCTβ2 in the regulation of branching formation and sustain the notion that c-Fos mediated activation of phospholipid synthesis is of importance during neuronal differentiation.