Christian De Duve: Explorer of the Cell Who Discovered New Organelles by Using a Centrifuge David D
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RETROSPECTIVE Christian de Duve: Explorer of the cell who discovered new organelles by using a centrifuge David D. Sabatini1 and Milton Adesnik Department of Cell Biology, New York University School of Medicine, New York, NY 10016 Christian de Duve, whose laboratory in the most advanced tools of enzymology, Louvain discovered lysosomes in 1955 and which were central to his later work. His defined peroxisomes in 1965, died at his Swedish sojourn was followed by a visit to home in Nethen, Belgium at the age of 95, on the laboratory of Carl and Gerty Cori in St. May 4, 2013. De Duve was the last of a group Louis, the Mecca of carbohydrate research at of eminent physiological chemists who, by the time, where he worked for a few months the 1940s and 1950s, began to explore the with Earl Sutherland, with whom he identi- subcellular organization of biochemical path- fied glucagon as a contaminant of insulin ways and thus forged the emergence of preparations widely used in those days. Glu- Modern Cell Biology. Christian De Duve, cagon was often referred to as the “hypergly- Albert Claude, and George Palade received cemic glycogenolytic factor” and de Duve the Nobel Prize in 1974 “for their discoveries later proudly referred to this work as his concerning the structural and functional or- “re-discovery of glucagon.” Sutherland’sfur- ganization of the cell.” ther work on the hormonal control of glyco- De Duve was born on October 2, 1917 in genolysis led him to the discovery of cAMP, Thames Ditton, United Kingdom, a town not for which he received the Nobel Prize far from London where his family had sought in 1971. refuge during World War I. After a classic In 1948, de Duve returned to Louvain, Christian de Duve. education in a Jesuit school in Antwerp, De where he intended to pursue his interest in Duve entered the Medical School of the carbohydrate metabolism and the action of by Claude—de Duve’s group also followed, Catholic University of Louvain in 1934, with insulin. With a newly assembled group as a control, the distribution and activity in no intention of becoming a scientist. He of young collaborators, de Duve decided the subcellular fractions of acid phospha- credited a student apprenticeship with Joseph to characterize the hexose phosphatase, tase, an enzyme with an optimum pH of — Bouckaert, who headed the physiology labo- which following the action of phosphorylase 5 and a very broad substrate specificity, — ratory, for sparking his interest in basic on glycogen was responsible for the unique which is found in almost all tissues. Be- ’ research. A major concern of Bouckaert sre- property of the liver to release glucose into the cause this enzyme was soluble when homo- fi search was the mechanism of action of in- blood. The researchers identi ed a liver phos- genates were prepared in a Waring blender, fi sulin. De Duve participated in experiments in phatase speci c for glucose-6-phosphate and the researchers expected to find it in the which rather crude preparation of the hor- correctly concluded that it was responsible for final supernatant obtained by Claude’s pro- mone were administered to hepatectomized that effect. Their subsequent attempts to pu- cedure. However, the activity was found to animals, which led him to adopt the idea that rify that enzyme set them on the track to the be present to various extents in all of the insulin acted primarily on the liver, and for discovery of lysosomes. fractions and, in particular, in the large many years he investigated with intensity the De Duve and his group observed that an granule fraction known to contain the mi- validity of this notion. acidic pH caused an irreversible precipitation tochondria. This finding was puzzling, as De Duve was in his last year of medical of the glucose-6-phosphatase, which led de were also the facts that the sum of the activ- school when the Germans invaded Belgium Duve to infer that the enzyme could be as- ities in all of the fractions was much greater in 1940. His involvement in the war was sociated with agglutinated cytoplasmic mem- than the activity in the whole homogenate, minor, as he was drafted as a medic, and branes. Hence, the group decided to follow whose activity was much lower than when fi soon was able to return to Louvain to nish the distribution of the enzyme in the various the Waring blender was used for the ho- medical school. However, by that time de cell fractions that could be obtained from mogenization. These intriguing observations ’ Duve s commitment to research was too liver homogenates by a procedure developed were obtained in December 1949 just be- strong for him to pursue a career in medi- by Claude, which used mild homogenization fore a weekend, and could have discour- ’ cine. After completing a Master sthesisin conditions and was designed to preserve the aged de Duve’s group from further studies chemistry at Louvain in 1946, de Duve spent integrity of subcellular organelles. on acid phosphatase, an enzyme that, after over a year as a postdoctoral fellow in Stock- It was most fortunate that in the course of all, was not of major interest to them and holm with Hugo Theorell, a pioneer in the these experiments, in addition to following — study of oxidizing enzymes who received the the distribution of glucose-6-phosphatase Author contributions: D.D.S. and M.A. wrote the paper. ’ Nobel Prize in 1955. Theorell s laboratory which was found to be primarily in the 1To whom correspondence should be addressed. E-mail: david. provided an ideal place for de Duve to learn small granule fraction called “microsomes” [email protected]. 13234–13235 | PNAS | August 13, 2013 | vol. 110 | no. 33 www.pnas.org/cgi/doi/10.1073/pnas.1312084110 Downloaded by guest on October 1, 2021 had been chosen as a control. It seems ser- lysosome obtained a morphological identity Again in this case, electron microscopy RETROSPECTIVE endipitous that they nevertheless decided to in 1955 as a result of a brief collaboration showed that, morphologically, the new or- store the samples in the refrigerator and with Alex Novikoff, a visiting scientist from ganelle corresponded to membrane-bounded reassay them at a later time. The results the Albert Einstein College of Medicine in particles of unknown function that had obtained five days later came to steer the New York, who had expertise in electron been recognized by microscopists to be researchers onto a new path that led them microscopy. Novikoff’s micrographs showed present in almost all tissues and had been to their discovery, first of the lysosome and that the “light mitochondrial” fraction con- designated “microbodies.” later the peroxisome. tained membrane bounded “dense bodies” Subsequent studies from many laborato- De Duve and his group found that, with similar to those present in the peri-canalicular ries, including those from de Duve’sandhis the exception of the activity in the final su- region of hepatocytes. former associates and students, showed that pernatant, acid phosphatase activities had The discovery of the lysosome inaugurated peroxisomes—first discovered in mammalian risen proportionately in all of the fractions, a new era in cellular physiology and path- tissues, where they play important metabolic as well as in the unprocessed homogenate, ophysiology, which was followed by the roles, including the β-oxidation of very long- fi fi whose activity now corresponded to the sum identi cation, rst in Louvain and then chain fatty acids by a pathway different from of the activities in all of the fractions. They throughout the world, of more than 40 that in mitochondria—are members of a large “ ” soon showed that the effect of ageing the lysosomal storage diseases resulting from family of evolutionarily related organelles fi fractions in the refrigerator could be recre- mutations in genes for speci c hydrolases. present in many different eukaryotic cell fi ated by treatments that disrupt membranes, The rst inkling that, in addition to types and organisms, including plants, and such as blender homogenization or repeated lysosomes, the light mitochondrial fraction protozoa, where they carry out distinct func- cycles of freeze-thawing. On this basis, de also harbored an as yet unknown organelle, tions and have been given specificnames, “ fi — Duve insightfully concluded that the latent was the nding that urate oxidase an en- such as glyoxysomes and glycosomes. Thus, enzyme” was sequestered within “mem- zyme that is not an acid hydrolase and does ” — with his discovery of peroxisomes, de Duve brane sacs that made it inaccessible to not show latency had a similar distribution once more laid the foundation for the the substrates. in subcellular fractions as acid phosphatase. growth of a new chapter in the burgeoning The studies on acid phosphatase prompted By 1960, de Duve had found that this was field of Cell Biology. de Duve’s group to develop a procedure that also true for catalase and for D-amino acid In 1974, soon after receiving the Nobel separated from the fraction rich in mitochon- oxidase, then thought to be mitochondrial Prize, de Duve, inspired by his experience at dria a “light mitochondrial fraction” or L enzymes. He later extended these findings The Rockefeller Institute, championed the fraction, which contained most of the acid to several other peroxide-producing oxidases creation in Brussels of a new multidisci- phosphatase but very little cytochrome oxi- with a sedimentation behavior similar to cat- plinary “International Institute of Cellular dase activity. What de Duve’s laboratory, in alase, an enzyme that breaks down their and Molecular Pathology,” with a transla- fact, accomplished was the purification of a product.