The evolution of a cell biologist

I am honored and humbled to receive the E. B. Wilson Medal and happy to share some reflections on my journey as a cell biologist. It took me a while to realize that my interest in biology would center on how cells are spatially and dynamically organized. From an initial fascination with cellular structures I came to appreciate that cells exhibit dynamism across all scales—from their molecules, to molecular complexes, to organelles. Uncovering the principles of this dynamism, including new ways to observe and quantify it, has been the guiding star of my work.

Jennifer Lippincott-Schwartz     

Lessons from a great developmental biologist

The announcement that Sir John Gurdon had been awarded the 2012 Nobel Prize for Medicine or Physiology was received with great joy by developmental biologists. It was a very special occasion because of his total dedication to science and turning the Golden Rule of western civilization – love your neighbor as yourself – into a reality in our field. This essay attempts to explain how John became such a great scientific benefactor, and to review some of his discoveries that are less well known than the nuclear transplantation experiments. A few personal anecdotes are also included to illustrate the profound goodness of this unique man of science.     

Genetics of asthma: a molecular biologist perspective

Viruses are the predominant infectious cause of asthma exacerbations in the developed world. In addition, recent evidence strongly suggests that viral infections may also have a causal role in the development of childhood asthma. In this article, we will briefly describe the general perception of how the link between infections and asthma has changed over the last century, and then focus on very recent developments that have provided new insights into the contribution of viruses to asthma pathogenesis. Highlighted areas include the contribution of severe early life viral infections to asthma inception, genetic determinants of severe viral infections in infancy, the differences in innate and adaptive immune system cytokine responses to viral infection between asthmatic and nonasthmatic subjects, and a potential vaccine strategy to prevent severe early life virally-induced illness.     

An unconventional route to becoming a cell biologist

I am honored to be the E. B. Wilson Award recipient for 2015. As we know, it was E. B. Wilson who popularized the concept of a “stem cell” in his book The Cell in Development and Inheritance (1896, London: Macmillan & Co.). Given that stem cell research is my field and that E. B. Wilson is so revered within the cell biology community, I am a bit humbled by how long it took me to truly grasp his vision and imaginative thinking. I appreciate it deeply now, and on this meaningful occasion, I will sketch my rather circuitous road to cell biology.I grew up in a suburb of Chicago. My father was a geochemist, and for everyone whose parents worked at Argonne National Laboratories, Downers Grove was the place to live. My father’s sister was a radiobiologist and my uncle was a nuclear chemist, both at Argonne; they lived in the house next door. Across the street from their house was the Schmidtke’s Popcorn Farm—a great door to knock on at Halloween. The cornfields were also super for playing hide-and-seek, particularly when you happened to be shorter than those Illinois cornstalks.Open in a separate windowElaine FuchsI remember when the first road in the area was paved. It made biking and roller-skating an absolute delight. Fields of butterflies were everywhere, and with development came swamps and ponds filled with pollywogs and local creeks with crayfish. It was natural to become a biologist. When coupled with a family of scientists and a mother active in the Girl Scouts, all the resources were there to make it a perfect path to becoming a scientist.I could hardly wait until I was in junior high school, when I could enter science fairs. You would think that my science-minded family might help me choose and develop a research project. True to their mentoring ethos, they left these decisions to me. My first project was on crayfish behavior. I recorded the response of the crayfish I had caught to “various external stimuli.” At the end of this assault, I dissected the crayfish and, using “comparative anatomy,” attempted to identify all the parts. The second project was no gentler. I focused on tadpole metamorphosis and the effects of thyroid hormone in accelerating development at low concentrations and death at elevated concentrations. Somehow, I ended up going all the way to the state fair, where it became clear that I had serious competition. That experience, however, whetted my appetite to gain more lab experience and to learn to read the literature more carefully.My experience with high school biology prompted me to gravitate toward chemistry, physics, and math. When it came to college, my father told me that if there was a $2000/year (translated in 2015 to be $30,000/year) reason why I should go anywhere besides the University of Chicago (where Argonne scientists received a 50% tuition cut for their children) or the University of Illinois (then $200/year tuition), we could “discuss” it further. Having a sister, father, aunt, and uncle who went to the University of Chicago, I chose the University of Illinois and saved my Dad a bundle of money. At Illinois, I thought I might revisit biology, but my choices for a major were “biology for teachers” or “honors biology.” The first did not interest me; the second seemed intimidating.I enrolled as a chemistry major. Four years went by, during which time I never took a biology class. I enjoyed quantum mechanics, physics, and differential equations, and problem solving became one of my strengths. In the midst of the Vietnam War era, however, Illinois was a hotbed of activity. I was inspired to apply to the Peace Corps, with a backup plan to pursue science that would be more biomedically relevant than quantum mechanics. I was accepted to go to Uganda with the Peace Corps, but with Idi Amin in office, my path to science was clear. Fortunately, the schools I applied to accepted me, even though, in lieu of GRE scores, I had submitted a three-page essay on why I did not think another exam was going to prove anything. I chose Princeton’s biochemistry program. This turned out to be a great, if naïve choice, as only after accepting their offer did I take a biochemistry class to find out what I was getting into. I chose to carry out my PhD with a terrific teacher of intermediary metabolism, Charles Gilvarg, who worked on bacterial cell walls. My thesis project was to tackle how spores break down one cell wall and build another as they transition from quiescence to vegetative growth.By my fourth year of graduate school, I was trained as a chemist and biochemist and was becoming increasingly hooked on biomedical science. I listened to a seminar given by Howard Green, who had developed a method to culture cells from healthy human skin under conditions in which they could be maintained and propagated for hundreds of generations without losing their ability to make tissue. At the time, Howard referred to them as epidermal keratinocytes, but in retrospect, these were the first stem cells ever to be successfully cultured. I was profoundly taken by the system, and Howard’s strength in cell biology inspired me. It was the perfect match for pursuing my postdoctoral research. The time happened to be at the cusp of DNA recombinant technology.At MIT, I learned how to culture these cells. I wanted to determine their program of gene expression and how this changed when epidermal progenitors embark on their terminal differentiation program. While the problem in essence was not so different from that of my graduate work at Princeton, I had miraculously managed to receive my PhD without ever having isolated protein, RNA, or DNA. Working in a quintessential cell biology lab and tackling a molecular biology question necessitated venturing outside the confines of the Green lab and beyond the boundaries of my expertise. Fortunately, this was easy at MIT. Richard Hynes, Bob Horvitz, Bob Weinberg, and Graham Walker were all assistant professors, and their labs were very helpful, as were those of David Baltimore and Phil Sharp, a mere walk across the street. On the floor of my building, Steve Farmer, Avri Ben Ze’ev, Gideon Dreyfuss, and Ihor Lemischka were in Sheldon Penman’s lab just down the hall, and they were equally interested in mRNA biology, providing daily fuel for discussions. Uttam Rhajbandary’s and Gobind Khorana’s labs were also on the same floor, making it easy to learn how to make oligo(dT)-Sepharose to purify my mRNAs. Vernon Ingram’s lab was also on the same floor, so learning to make rabbit reticulocyte lysates to translate my mRNAs was also possible. Howard bought a cryostat, so I could section human skin and separate the layers. And as he was already working with clinicians at Harvard to apply his ability to create sheets of epidermal cells for the treatment of burn patients, I had access to the leftover scraps of human tissue that were also being used in these operations.The three years of my postdoc were accompanied by three Fuchs and Green papers. The first showed that epidermal keratinocytes spend most of their time expressing a group of keratin proteins with distinct sequences. The second showed that these keratins were each encoded by distinct mRNAs. The third showed that, as epidermal keratinocytes commit to terminally differentiate, they switch off expression of basal keratins (K5 and K14) and switch on the expression of suprabasal keratins (K1 and K10). That paper also revealed that different stratified tissues express the same basal keratins but distinct sets of suprabasal keratins. I am still very proud of these accomplishments, and my MIT experience made me thirst to discover more about the epidermis and its stem cells.My first and only real job interview came during my second year of postdoc, at a time when I was not looking for a job. I viewed the opportunity, initiated by my graduate advisor, as a free trip home to visit my parents and my trial run to prepare me for future searching. I was thrilled when this interview materialized into an offer to join the faculty, for which the University of Chicago extended my start time to allow me to complete my three years with Howard.Times have clearly changed, and it is painful to see talented young scientists struggle so much more today. That said, I have never looked ahead very far, and having a lack of expectations or worry is likely to be as helpful today as it was then. I am sure it is easier said than done, but this has also been the same for my science. I have always enjoyed the experiments and the joy of discovery. There was no means to an end other than to contemplate what the data meant in a broader scope.I arrived at the University of Chicago with a well-charted route. My aim was to make a cDNA library and clone and characterize the sequences and genes for the differentially expressed keratins I had identified when I was at MIT. It was three months into my being at Chicago when my chair lined up some interviews for me to hire a technician. I was so immersed in my science that I did not want to take time to hire anyone. I hired the first technician I interviewed. Fortunately, it worked out. However, I turned graduate students away the first year, preferring to carry out the experiments with my technician and get results. After publishing two more papers—one on the existence of two types of keratins that were differentially expressed as pairs and the other on signals that impacted the differential expression of these keratin pairs, I decided to accept a student, who analyzed the human keratin genes. My first postdoc was a fellow grad student with me at Princeton; she studied signaling and keratin gene expression. My second postdoc was initiated by my father, who chatted with him at the elevator when I was moving into my apartment. He set up DNA sequencing and secondary-structure prediction methods, and the lab stayed small, focused, and productive.I was fascinated by keratins, how they assembled into a network of intermediate filaments (Ifs). When thalassemias and sickle cell anemia turned out to be due to defects in globin genes, I began to wonder whether there might be human skin disorders with defective keratin genes. I had no formal training in genetics, and there were no hints of what diseases to focus on. Thus, rather than using positional cloning to identify a gene mutation associated with a particular disease, we took a reverse approach: we first identified the key residues for keratin filament assembly. After discovering that mutations at these sites acted dominant negatively, we engineered transgenic mice harboring our mutant keratin genes and then diagnosed the mouse pathology. Our diagnoses, first for our K14 mutations and then for our K10 mutations, turned out to be correct: on sequencing the keratins from humans with epidermolysis bullosa simplex (EBS), we found K14 or K5 mutations; similarly, we found K1 or K10 mutations in affected, but not in unaffected, members of families with epidermolytic hyperkeratosis (EH). Both are autosomal-dominant disorders in which patients have skin blistering or degeneration upon mechanical stress. Without a proper keratin network, the basal (EBS) or suprabasal (EH) cells could not withstand pressure. Ironically, family sizes of all but the mildest forms of these disorders were small, meaning that the disorders were not amenable to positional cloning. But the beauty of this approach is that once we had made the connection to the diseases, we understood their underlying biology. In addition, the IF genes are a superfamily of more than 100 genes differentially expressed in nearly all tissues of the body. Once we had established EBS as the first IF gene disorder, the pathology and biology set a paradigm for a number of diseases of other tissues that turned out to be due to defects in other IF genes.Fortunately, I had students, Bob Vassar (professor, Northwestern University) and Tony Letai (associate professor, Harvard Medical School), and a postdoc, Pierre Coulombe (chair, Biochemistry and Molecular Biology, Johns Hopkins University), who jumped into this fearless venture with me. We had to go off campus to learn transgenic technology. I had never worked with mice before. When Bob returned to campus with transgenic expertise, we hired and trained Linda Degenstein, whose love for animal science was unparalleled. Pierre’s prior training in electron microscopy was instrumental in multiple ways. Additionally, I was not a dermatologist and had no access to human patients. Fortunately Amy Paller, MD, at Northwestern volunteered to work with us.The success of this project attests to an important recipe: 1) Pursue a question you are passionate about. 2) In carrying out rigorous, well-controlled experiments, each new finding should build upon the previous ones. 3) If you have learned to be comfortable with being uncomfortable, then you will not be afraid to chart new territory when the questions you are excited to answer take an unanticipated turn. 4) Science does not operate in a vacuum. Interact well with your lab mates and take an interest in their science as well as your own. And wherever you embark upon a pathway in which the lab’s expertise is limited, do not hesitate to reach out broadly to other labs and universities.I have followed this recipe now for more than three decades, and it seems to work pretty well. A lab works only when its students and postdocs are interactive, naturally inquisitive, and freely share their ideas and findings. I have been blessed to have a number of such individuals in my lab over the years. When push comes to shove, I am always inclined first to shave from the “brilliant” category and settle for smart, nice people who are passionate and interactive about science and original and unconventional in their thinking.So what questions have I been most passionate about? I have always been fascinated with how tissues form during development, how they are maintained in the adult, and how tissue biology goes awry in human disorders, particularly cancers. I first began to think about this problem during my days at Princeton. I also developed a dogma back then that I still hold: to understand malignancies, one must understand what is normal before one can appreciate what is abnormal. I think this is why I have spent so much of my life focusing on normal tissue morphogenesis, despite my passion for being at the interface with medicine. And because skin has so many amazingly interesting complexities, and because it is a great system to transition seamlessly between a culture dish and an animal, I have never found a reason to choose any other tissue over the one I chose many years back.I will not dwell on the various facets of skin biology we have tackled over the years. Our initial work on keratins was to obtain markers for progenitors and their differentiating lineages. This interest broadened to understanding how proliferative progenitors form cytoskeletal networks and how the cytoskeleton makes dynamic rearrangements during tissue morphogenesis.From the beginning, the lab has also been fascinated by how tissue remodeling occurs in response to environmental signals. Indeed, signals from the microenvironment trigger changes in chromatin dynamics and gene expression within tissue stem cells. Ultimately, this leads to changes in proteins and factors that impact on cell polarity, spindle orientation, asymmetric versus symmetric fate specifications, and ultimately, the balance between proliferation and differentiation.The overarching theme of my lab over these decades is clear, namely, to understand the signals that unspecified progenitors receive that instruct them to generate a stratified epidermis, make hair follicles, or make sweat and sebaceous glands. And if we can understand how this happens, then how are stem cells born, and how do they replace dying cells or regenerate tissue after injury? And, finally, how does this process change during malignant progression or in other aberrant skin conditions?In tackling tissue morphogenesis, I have had to forgo knowing the details of each tree and instead focus on the forest. There are many times when I stand back and can only admire those who are able to dissect beautiful cellular mechanisms with remarkable precision. But I crossed that bridge some years ago in tackling a problem that mandates an appreciation of nearly all the topics covered in Bruce Alberts’ textbook Molecular Biology of the Cell. I am now settled comfortably with the uncomfortable, and the problem of tissue morphogenesis in normal biology and disease continues to keep me more excited about each year’s research than I was the previous year. Perhaps the difference between my days as a student, postdoc, and assistant professor and now is that my joy and excitement is as strong for those I mentor and have mentored as it is for myself.     

William Bateson: a biologist ahead of his time

William Bateson coined the term genetics and, more than anybody else, championed the principles of heredity discovered by Gregor Mendel. Nevertheless, his reputation is soured by the positions he took about the discontinuities in inheritance that might precede formation of a new species and by his reluctance to accept, in its fullblooded form, the view of chromosomes as the controllers of individual development. Growing evidence suggests that both of these positions have been vindicated. New species are now thought to arise as the result of genetic interactions, chromosomal rearrangements, or both, that render hybrids less viable or sterile. Chromosomes are the sites of genes but genes move between chromosomes much more readily than had been previously believed and chromosomes are not causal in individual development. Development, like speciation, requires an understanding of the interactions between genes and the interplay between the individual and its environment.     

The Darwinian revolution as viewed by a philosophical biologist

Darwin proclaimed his own work revolutionary. His revolution, however, is still in progress, and the changes that are going on are reflected in the contemporary historical and philosophical literature, including that written by scientists. The changes have taken place at different levels, and have tended to occur at the more superficial ones. The new ontology that arose as a consequence of the realization that species are individuals at once provides an analytical tool for explaining what has been happening and an example of the kind of changes that seem in order. It provides a clear distinction between the roles of history and of laws of nature. Pre-Darwinian evolution was superficial in the sense that it treated change as either as something pre-ordained or else due to timeless laws of nature, rather than historical contingency. Darwinism puts the ontological emphasis upon concrete, particular things (individuals) and therefore delegitimizes both essentialistic and teleological ways of thinking. However, traditional ways of thinking have persisted, if not explicitly, then often as assumptions and procedures that are merely implicit or even unconscious. As a result, anti-evolutionary attitudes continue to influence the practice of evolutionary biology as well as the study of its history and philosophy.     

著名的生物化学与分子生物学家吴冠芸教授

吴冠芸教授是一位毕生活跃在医学科学前沿的女科学家、教育家。她在科教战线上辛勤耕耘逾50载,成就卓著,声名斐然。在科学研究上,她的突出贡献是：在我国首先建立起一系列常见的和严重的遗传病的基因诊断新方法、新技术,并将之推广应用,取得了显著的社会效益,翻开了我国遗传病研究和防治工作的新篇章,为提高人民健康水平带来福音,因而多次获得国家级和部级嘉奖,并受任为世界卫生组织遗传病社区防治合作中心主任。吴冠芸教授也是在分子水平上研究中医药疗效原理的开拓者之一,多有建树。改革开放后,她壮心不已,奔波于国际学术讲坛,为中国相关科学领域在国际科坛上赢得了一席之地。吴冠芸教授已发表论文140余篇,综述50余篇,主编出版专著3部。她曾作为中国医学科学院基础医学研究所生物化学与分子生物学系多年的主要负责人之一,为生物化学与分子生物学的学科建设和人才培养作出了重要贡献,尤其在培养人才方面,她甘为人梯,勤于育人。培养了不少有成就的人才,出自其门下的莘莘学子遍布海内外,受过短期培养的科技人员和医务工作者更不胜枚举。吴冠芸教授不愧为“知识先锋,道德楷模”。