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Christian De Duve: Explorer of the Cell Who Discovered New Organelles by Using a Centrifuge David D

Christian De Duve: Explorer of the Cell Who Discovered New Organelles by Using a Centrifuge David D

RETROSPECTIVE : Explorer of the who discovered new by using a centrifuge David D. Sabatini1 and Milton Adesnik Department of Cell , New York University School of , New York, NY 10016

Christian de Duve, whose laboratory in the most advanced tools of enzymology, Louvain discovered in 1955 and which were central to his later work. His defined in 1965, died at his Swedish sojourn was followed by a visit to home in Nethen, at the age of 95, on the laboratory of Carl and 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 as a contaminant of ways and thus forged the emergence of preparations widely used in those days. Glu- Modern . Christian De Duve, cagon was often referred to as the “hypergly- , and George Palade received cemic glycogenolytic factor” and de Duve the 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 , 1917 in genolysis led him to the discovery of cAMP, Thames Ditton, United , a town not for which he received the Nobel Prize far from where his family had sought in 1971. refuge during . After a classic In 1948, de Duve returned to Louvain, Christian de Duve. education in a Jesuit school in , De where he intended to pursue his interest in Duve entered the of the carbohydrate 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 . 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 with an optimum pH of — Bouckaert, who headed the labo- which following the action of phosphorylase 5 and a very broad substrate specificity, — ratory, for sparking his interest in basic on was responsible for the unique which is found in almost all tissues. Be- ’ research. A major concern of Bouckaert sre- property of the to release into the cause this enzyme was soluble when homo- fi search was the 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- 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 , 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 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 , a pioneer in the these experiments, in addition to following — study of oxidizing 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 September 30, 2021 had been chosen as a control. It seems ser- 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 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 “.” later the . 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 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 , including , 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 , tions and have been given specificnames, “ fi — Duve insightfully concluded that the latent was the nding that an en- such as and . 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 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 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 ,” with a transla- fact, accomplished was the purification of a product. De Duve had the insight that a func- tional mission, which he originally directed new organelle solely on the basis of analytical tional linkage between these enzymes existed, and at his 80th birthday was renamed the biochemical procedures, guided by meas- which was made possible by their inclusion “ ” urements of specific enzymatic activities, in the same particle. Thus, the concept of de Duve Institute. which are now regarded as “marker a peroxisome was being born, but it was De Duve left a major imprint in the bi- enzymes.” The finding that four other acid not to be presented publicly until several ological through the work he carried hydrolases—β-glucuronidase, cathepsin D, years later, after de Duve had begun to split out on both sides of the Atlantic and through ribonuclease, and DNAse—displayed latency his time between Louvain and New York. the many who trained with him. He and were also enriched in the L fraction led In 1962 de Duve accepted an attractive was a highly cultured person who spoke four fl de Duve to formulate the “lysosome” con- offer to create and direct a laboratory at The languages uently and wrote elegant prose in ’ cept: that is, a membrane-bounded organelle Rockefeller Institute in New York, while at least two of them. De Duve s interests ex- fi that contains acid hydrolases with various maintaining his laboratory in Louvain. He tended well beyond the areas of his scienti c specificities and whose main function is the was able to transfer to his new laboratory the contributions, into the realms of philosophy, intracellular digestion of macromolecules. various technologies developed in Louvain the theory of knowledge, the origin of , Later, as progress was being made in eluci- by arranging for regular visits of his major and the of the eukaryotic cell. He dating the broad function of lysosomes, De Belgian associates to New York. In both lab- published extensively his thoughts on ques- Duve also coined the terms “,” oratories, de Duve continued the character- tions from almost all these fields, in lucid “phagocytosis,” and “” to desig- ization of the newly discovered oxidase- articles as well as in books. De Duve also nate pathways that bring substrates for di- containing particles first identified in wrote many engaging historical accounts of gestion in lysosomes and, today, are active liver. Three years later, only after particles the major scientific discoveries made in his fields of research in cell biology. with a similar sedimentation behavior and laboratories and in all of them he took great Remarkably,deDuvearrivedatthelyso- biochemical properties were found in rat care to give credit to his younger associates some concept without resorting to any kidney and in the ciliated protozoan Tetrahy- and to point out their specificcontributions. microscopic examination of his samples. mena pyriformis, did he announce, at a meet- Christian de Duve was a warm colleague In fact, there was no microscope in his ing of the American Society of Cell Biology, and a fascinating conversationalist. Those of laboratory and he entitled his Nobel lecture that he had discovered a new organelle, for uswhohadthegoodfortuneofknowinghim “Exploring Cells with a Centrifuge.” The which he proposed the name “peroxisome.” personally will sorely miss him.

Sabatini and Adesnik PNAS | August 13, 2013 | vol. 110 | no. 33 | 13235 Downloaded by guest on September 30, 2021