Professor Lech Wojtczak (1926-2019) as remembered by his four former students / Profesor Lech Wojtczak (1926-2019) we wspomnieniach czwórki swych wychowanków.

The sudden death of Professor Lech Wojtczak, the great Polish biochemist and a remarkable man, our Mentor and Friend, left us in sorrow and emptiness difficult to accept. Two years have passed already from this event and our memories seem to be even more vivid, and his absence even more felt. Hence we decided to put on paper our personal reflections on Lech Wojtczak, each of us concentrating on a slightly different aspect of this towering figure. We tried to focus on memories and comments that were not mentioned in official obituaries that followed His passing away. Therefore do not expect to find here a comprehensive text on the Founder of Polish Bioenergetics, and a famous Polish biochemist, but rather a set of subjective comments on a man who made us scientists. Our memories are presented in a chronological order. The first chapter is by Professor Jolanta Baranska, who joined the group of Lech Wojtczak in 1968, followed by a chapter by Professor Maciej J. Nalecz, who joined Lech in 1976, then Professor Konrad S. Famulski (1978) and finally followed by a chapter by Professor Adam Szewczyk, the youngest, joining the group in 1984.

Memories and comments on the last 42 years in the Nencki Institute as seen through the eyes of a former director.

The author describes his 42 years in the Nencki Institute (1976-2018), with special emphasis on people and events that marked the life of the Institute during this time. The article contains some personal memories and comments, starting with author's early research in the Nencki Institute, under communism, years of directorship of the Institute (1991-2002) and, finally, the current time.

[Carnitine - mitochondria and beyond]. / Karnityna - mitochondria i nie tylko.

Carnitine [(3R)-3-hydroxy-4-(trimethylazaniumyl)butanoate] in mammals is mainly delivered with diet. It enters the cell due to the activity of organic cation/carnitine transporter OCTN2 (SLC22A5), it can be as well transported by CT2 (SLC22A16) and a transporter of neutral and basic amino acids ATB0, + (SLC6A14). The hydroxyl group of carnitine is able to form esters with organic acids (xenobiotics, fatty acids) due to the activity of acylcarnitine transferases. Carnitine is necessary for transfer of fatty acids to mitochondria: in functioning of the so-called carnitine shuttle an essential role is fulfilled by palmitoylcarnitine transferase 1, carnitine carrier (SLC25A20) in the inner mitochondrial membrane and palmitoylcarnitine transferase 2. Oxidation of fatty acids takes also place in peroxisomes. The produced medium-chain acyl derivatives are exported as acylcarnitines, most probably by OCTN3 (Slc22a21). It has been postulated that acylcarnitines can cross the outer mitochondrial membrane through the voltage-dependent anion channel (VDAC) and/or through the palmitoycarnitine transferase 1 oligomer. Mutations of genes coding carnitine plasma membrane transporters result in the primary carnitine deficiency, with symptoms affecting normal functioning of muscles (including heart) and brain. Mechanisms regulating functioning of these transporters have been presented with emphasis on their role as potential therapeutic targets.

Interaction of palmitoylcarnitine with protein kinase C in neuroblastoma NB-2a cells.

As reported previously [Acta Neurobiol. Exp. 57 (1997) 263], palmitoylcarnitine was observed to promote differentiation of neuroblastoma NB-2a cells with a concomitant inhibition of proliferation and of the phorbol ester stimulated activity of the protein kinase C (PKC). In the present study, palmitoylcarnitine was observed to inhibit phosphorylation of the PKC peptide substrate and to completely diminish binding of phorbol 12-myristate-13-acetate (PMA), although the effect was found to be uncompetitive. The exposure of NB-2a cells to palmitoylcarnitine in the presence of PMA resulted in a dramatic decrease in phosphorylation of the conventional and novel isozymes of PKC, mainly on serine. This effect was observed to be dose dependent. Inhibitors of serine/threonine phosphatases were not influencing the effect of palmitoylcarnitine what can point to an interaction between PKC and palmitoylcarnitine, affecting the process of autophosphorylation. These findings suggest that pamitoylcarnitine could be a natural modulator of PKC activity, thus regulating the process of cell differentiation.