Accumulation of palmitoylcarnitine in neuroblastoma NB-2a cells affects the expression, phosphorylation and localization of B-50 protein

Abstract

Accumulation of palmitoylcarnitine inside the neuroblastoma NB‐2a cells was observed to promote their differentiation. Exposure of these cells to carnitine resulted in an intensive estrification of this compound with palmitate. Accumulation of palmitoylcarnitine inside the cells coincided with an increase of the B‐50 protein. A phorbol ester stimulated phosphorylation of the B‐50 protein and of a coprecipitated 78 kDa band was diminished by 50% in the presence of palmitoylcarnitine. A transfer of B‐50 to the membranes was observed to occur at increased intracellular palmitoylcarnitine (upon treatment with 1 mM carnitine). A role of palmitoylcarnitine, as a protein kinase C modulator and a store of precursor for the process of palmitoylation has been postulated.

Involvement of OCTN2 and B0,+in the transport of carnitine through anin vitromodel of the blood–brain barrier

“…2003). An increased intracellular content of this long‐chain acylcarnitine was further correlated with a diminished phosphorylation of GAP‐43 (also known as B‐50, F1, pp45, neuromodulin) (Mizgalska et al . 1998; Sobiesiak‐Mirska and Nałęcz 2002), a protein involved in neuronal development, neuroplasticity and neurotransmission and located at the cross‐roads of several signalling pathways (Oestreicher et al .…”

Carnitine: transport and physiological functions in the brain

“…Palmitoylcarnitine, either administered or synthesized and accumulated in neuroblastoma NB-2a cells, was shown to increase the expression of GAP-43, its transfer to the membranes and to decrease its phorbolstimulated phosphorylation by protein kinase C (Mizgalska et al, 1998). The activity of this kinase was shown to be inhibited by palmitoylcarnitine (Robinson, 1992), moreover, the degree of protein kinase C inhibition was correlated with increase of the intracellular palmitoylcarnitine content, modulated by inhibition of carnitine palmitoylcarnitine transferase I with etomoxir (Nałe z cz et al, 1997).…”

Palmitoylcarnitine regulates estrification of lipids and promotes palmitoylation of GAP‐43

“…Palmitoylcarnitine was shown to inhibit GAP-43 interaction with PKC and its phosphorylation [8,14] and to promote its transfer to membrane fraction [14]. GAP-43 is known to be palmitoylated at Cys 3 and Cys 4 [15].…”