PROFILE

Profile of Michael Grunstein

n 2001, half a decade after researchers announced the arrival of Dolly, the Ifirst mammal cloned from an adult somatic stem cell, scientists in the private sector decided to clone a pet cat. A couple of years later the enterprise went commercial, and eager pet owners lined up for the service. However, disappointment inevitably ensued: although the clones were genetically identical to the original pets, cloned cats often looked and acted no- thing like their predecessors. Michael Grunstein, were he so inclined, might have said, “I told you so.” Grunstein, a distinguished professor of biological chemistry at the University of California, Los Angeles (UCLA), has devoted a lifetime of research to exploring how identical genes can be expressed differ- ently to create unique individuals. Elec- ted to the National Academy of Sciences Michael Grunstein (center) shared the 2011 Lewis S. Rosenstiel Award for Distinguished Work in Basic in 2008, Grunstein’s findings have un- Medical Science with C. David Allis (far left). Pictured (from left): Allis, Rockefeller University; James E. raveled the secrets behind the subtle in- Haber, Director, Rosenstiel Basic Medical Sciences Research Center, Brandeis University; Grunstein; terplay among genes, proteins, enzymes, Frederick M. Lawrence, President, Brandeis University; and Michael Rosbash, Brandeis University. and chemical markers that determines how genes and gene components are read, expressed, transferred, and copied. coauthors described how to use patterns of several stories high. Here I was, 18 years These secrets were discovered not by histone modifications in cells to predict old, working with these things.” working with people—or even cats—but clinical outcomes of prostate cancer, the Grunstein credits an instructor at with yeast. second leading cause of cancer death in McGill University for sparking his interest A long strand of DNA must undergo American men (1). Histone modification in genetics. “Probably the most important several stages of dense packing to fit within patterns identified in that article predicted influence in college was a professor the nucleus of a microscopic cell. In the tumor recurrence independently of known named John Southin,” Grunstein recalls. first stage, a section of the DNA molecule clinical and pathological factors and better “He taught genetics in a way that made it coils around a set of eight proteins called than any other biomarkers known at the extremely interesting. Instead of teaching histones, akin to DNA “thread” winding time. As Grunstein says, quoting the the facts of genetics, he would describe around a histone “spool.” However, his- French molecular biologist Jacques Mon- papers in which there was an error in the tones provide more than structural sup- od, “What is true for E. coli is true for work. Finding the error was a challenge. port. Thanks in part to Grunstein’s work an elephant.” It was fantastic!” with yeast, researchers now know that histones help regulate gene expression. A Teacher’sInfluence Tools of the Trade Grunstein’s research concerns the func- Grunstein was born in 1946 in Romania, Grunstein decided to pursue genetics in tion of acetyl groups—small molecules the only surviving child of two Holocaust graduate school. At first, he assumed he composed of carbon, hydrogen, and survivors. After the war the family moved should continue his education in Canada, oxygen, that bind to chemical outcroppings to Montreal, Canada, where Grunstein where he lived. However, a faculty on specific histones, or histone “tails”. attended McGill University. Although his member at McGill, who had just returned Using mutations in the lysine amino acids, parents were intelligent, motivated, and from a sabbatical in Scotland, suggested at which acetyl groups are added, Grun- careful to instill in him the value of hard that Grunstein expand his horizons by stein found that the sites were necessary work, Grunstein recalls that they were at studying abroad. So Grunstein went to grad- for gene activity. Acetylation is now times wary of his determination to make uate school at the University of Edinburgh thought to uncoil DNA in the chromo- a living as a scientist. “Like many recent in Scotland. There he began working with some. Once uncoiled, the genetic in- immigrants, they were self taught. They a professor named Max Birnstiel. Under formation within the DNA molecule would have been much happier if I had Birnstiel’s tutelage, Grunstein helped becomes accessible so that it can be read, gone to medical school. Still, they always characterize the first chemically isolated or transcribed. Removal of the acetyl supported and respected my decision.’” genes of an eukaryote—those for the groups, or deacetylation, causes the DNA Grunstein’s first taste of science came rRNAs of the ribosome, where cellular to wind back, repressing transcription. from a summer job between university protein synthesis takes place. Grunstein These concepts are not restricted to terms. Bored with his usual after-school calls this period, “a breakthrough in my yeast, however. Grunstein’s work had— jobs at gas stations, Grunstein secured scientific life.” At this point, the field of and continues to have—implications a job performing gas chromatography at molecular biology was just picking up for humans as well. Knowledge of the an industrial laboratory. The draw, says developmental regulation that occurs Grunstein, was the impressive equipment. in histones is easily transferred to human He explains, “When you’re separating the ’ ’ This is a Profile of a recently elected member of the Na- genetics. In 2005 Grunstein s postdoctoral gasses from liquid air, you re separating tional Academy of Sciences to accompany the member’s fellow, Siavash Kurdistani, and several them on an enormous column, which is Inaugural Article on page 13153 in issue 32 of volume 106.

www.pnas.org/cgi/doi/10.1073/pnas.1116909108 PNAS | November 15, 2011 | vol. 108 | no. 46 | 18597–18599 Downloaded by guest on September 27, 2021 steam, and Grunstein sought out sol- UCLA. As a newly minted professor, a specific gene related to cell mating. Why utions to the practical aspects of genetic Grunstein set out to identify genes for would such a general protein affect a very manipulation. “How do you deal with a histones that switch on and off between specific function? His team soon found gene in a test tube?” he asked. “Which one subtype and another during cellular that lysine 16 interacted genetically with portion of the gene is transcribed in the development. His model organism of the SIR3 heterochromatin protein (4). RNA? Which portion is not transcribed? choice was the sea urchin, whose DNA “This was really special because it How do you separate genes from contains many repetitive copies of histone suggested a whole different type of regu- each other?” genes. The sea urchins suited his work, at lation, where regulatory proteins inter- To answer these questions, Grunstein first. But bad weather complicated mat- acted with histones to exert their function. needed more time and more training. ters. “Sea urchins were hard to get, and That is now a common occurrence in the After graduating from the University of their gametes were completely gone in the field called ‘epigenetics’.” Edinburgh, Grunstein returned to North storms,” Grunstein recalls. So he began America to pursue postdoctoral research looking for a different model organism. Day at a Time at Stanford University. His work with ri- In a fortuitous turn of events, Grunstein Grunstein says the greatest joy of his ca- bosomal RNAs in graduate school piqued attended a scientific lecture on yeast ge- reer is not the awards he has received or his interest in messenger RNAs. Under netics and “fell in love.” With yeast he the fields of study inspired by his work: it is the guidance of Larry Kedes, Grunstein could perform experiments that were not the extraordinary graduate students and began to examine the mRNAs and genes possible in the sea urchin. post-docs he has known during his years at for the histone proteins. However, be- UCLA. “I’ve been extremely fortunate,” cause scientists had not yet figured out an Burrowing into Histones he says. “I’ve had some graduate students easy way to purify genes, he lacked the In a 1988 publication (3), Grunstein de- and post-docs over the years that I didn’t necessary tools to complete his studies. scribed how the nucleosome repressed consider to be my students so much as “At that time, you couldn’t easily separate yeast transcription in vivo. By blocking my colleagues—colleagues at an earlier the genes for one messenger RNA from histone synthesis in replicating cells, stage in their development.” Although he the genes for another. And separation is Grunstein and his graduate student de- claims not to have any long-term goals everything. If you couldn’t separate them pleted the chromosomes of nucleosomes. beyond surviving to see the next five from each other you couldn’t study Without histones, the pair found, every years, there are some questions that in- them,” he said. normally repressed gene they examined terest Grunstein. How does epigenetic Fortunately, Grunstein happened to be was activated. Before that work, re- switching take place? How do certain in the right place at the right time. By searchers had reported in vitro experi- unusual histone lysines help regulate a stroke of luck, researchers at Stanford ments, but the field was far from con- mammalian cell replication and differen- were developing the exact tools that vinced that the process worked the same tiation? What are the heterochromatin- Grunstein required, particularly a then- way in living cells. specific functions of the tail in a specific enterprising technique for studying genes Some of Grunstein’s earliest findings type of yeast histone known as H3? called cloning. Grunstein knew that he were also the most unexpected. Re- In his Inaugural Article (5), Grunstein had found what he needed, and so, he searchers had learned of numerous his- addresses this last question. In the article, recalls, “I pestered my way into Dave tone subtypes in flies and humans and sea Grunstein and his graduate student com- Hogness’s lab even though every lab urchins, but it remained unclear whether piled genome-wide maps of histone bench was taken. I bothered him until these subtypes performed essential func- binding within heterochromatin—aregion he accepted me.” Cloning would soon tions. Grunstein’s laboratory carried out of tightly packed DNA and histones lo- transform genetics research, but the the first cause-and-effect histone gene cated near the center and ends of a chro- technology was far from perfect. It re- mutation experiments. They showed that mosome. The study finds that, whereas mained unclear how to distinguish be- when a subtype is removed from a cell, a related histone tail, the H4 N terminus, tween distinct genes from different the cell survives quite well, suggesting recruits proteins that promote deacetyla- bacterial colonies. In Hogness’s labora- that some histone subtypes performed tion and gene silencing, the H3 N termi- tory, Grunstein developed an approach redundant functions. “The field had gen- nus neither recruits nor spreads these called “colony hybridization” (2), which erally thought that since histones are so proteins. Instead, deacetylation at the H3 allowed researchers to use a DNA or conserved in evolution, anything you did tail promotes restructuring of the packed RNA probe to isolate a single gene en- to the histone would kill the cell. But DNA once the silencing proteins have coding an individual messenger RNA. here, we found that subtypes were not already spread. Before this work, Grun- For the field of genetics, this was a essential,” he said. stein recalls, “It wasn’t clear why the H3 breakthrough. Finally, Grunstein had Burrowing deeper, Grunstein began amino terminus was necessary for the re- a tool that would make it possible to clipping away at the amino termini of pressive function of yeast heterochroma- clone individual genes. histones and found that this entire region tin.” It was great to learn that it had a of each protein was not required for cell function distinct from that of histone H4. Falling in Love...with Yeast viability. Eventually Grunstein and his Despite years of groundbreaking work, Grunstein’s technique soon opened up students developed a histone that lacked Grunstein still gets excited by new dis- new avenues of genetics research. Beyond 25% of its sequence—and still, the cell coveries. Reflecting on his election into the tool’s original intended use, re- lived. If the sequence was not required the National Academy of Sciences, he searchers soon adapted the principle be- for viability, Grunstein wondered, why recalls, “I was thrilled. It’s something that hind colony hybridization to clone genes was the sequence there? Finally in 1988, I always thought happened to other peo- in bacterial viruses, yeast, and even hu- a persistent graduate student studying ple. But when it happens to yourself, man cells. Eager to ride the momentum, histone H4 found that, although deletion it’s such a wonderful honor.” Grunstein left Stanford in 1975 after after deletion in the amino terminus had three years as a postdoctoral scientist to no effect on viability, removal of the se- Jenny Ruth Morber, Freelance Science set up a laboratory of his own at the quence surrounding lysine 16 affected Writer

18598 | www.pnas.org/cgi/doi/10.1073/pnas.1116909108 Morber Downloaded by guest on September 27, 2021 1. Seligson DB, et al. (2005) Global histone modification 3. Han M, Grunstein M (1988) Nucleosome loss activates Saccharomyces cerevisiae. Proc Natl Acad Sci USA 87: patterns predict risk of prostate cancer recurrence. yeast downstream promoters in vivo. Cell 55:1137– 6286–6290. Nature 435:1262–1266. 1145. 5. Sperling AS, Grunstein M (2009) Histone H3 N-terminus 2. Grunstein M, Hogness DS (1975) Colony hybridization: 4. Johnson LM, Kayne PS, Kahn ES, Grunstein M (1990) regulates higher order structure of yeast hetero- A method for the isolation of cloned DNAs that contain Genetic evidence for an interaction between SIR3 and chromatin. Proc Natl Acad Sci USA 106:13153– a specific gene. Proc Natl Acad Sci USA 72:3961–3965. histone H4 in the repression of the silent mating loci in 13159.

Morber PNAS | November 15, 2011 | vol. 108 | no. 46 | 18599 Downloaded by guest on September 27, 2021