A Decade of Molecular Cell Biology: Achievements and Challenges

PERSPECTIVES

a reaction–diffusion mechanism. I attribute 10-YEAR ANNIVERSARY SERIES — VIEWPOINT this concept to Eric Karsenti, who mooted the idea in the mid 1980s for signals dif- A decade of molecular cell biology: fusing away from DNA in eggs. However, it wasn’t proven until the development of fluorescence resonance energy transfer achievements and challenges (FRET)-based activity biosensors in the past decade2,3. In general, fluorescence sensors Asifa Akhtar, Elaine Fuchs, Tim Mitchison, Reuben J. Shaw, Daniel St Johnston, of biochemical activity are a very important Andreas Strasser, Susan Taylor, Claire Walczak and Marino Zerial development.

Abstract | Nature Reviews Molecular Cell Biology celebrated its 10‑year anniversary Reuben J. Shaw. One area close to our own during this past year with a series of specially commissioned articles. work is the unexpected re-emergence of To complement this, here we have asked researchers from across the field for their metabolism and its relationship to growth insights into how molecular cell biology research has evolved during this past control and cancer. Advances in autophagy decade, the key concepts that have emerged and the most promising interfaces continue to amaze me in terms of how little basic information we actually have on how a that have developed. Their comments highlight the broad impact that particular cell works. Autophagy regulators are highly advances have had, some of the basic understanding that we still require, and the conserved proteins in a central cell biologi- collaborative approaches that will be essential for driving the field forward. cal process that is deregulated in common human diseases, yet much of the biochemical framework for this process has been What do you feel have been the Takahashi were paradigm-shifting. Their decoded only recently. Other newly decoded most significant, and perhaps most work reported the creation of induced pluri- central regulators and processes, ranging surprising, new concepts to emerge in potent stem (iPS) cells from mouse skin from cilia to sirtuins, microRNAs (miRNAs) molecular cell biology during the past decade? fibroblasts when cultured in embryonic stem and pathways such as those involving Has this progress been enabled by a particular cell (ESC) conditions1. It was remarkable Hippo and mammalian target of rapamycin technical advance? that transient overexpression of a mere four (mTOR), underlying so much biology, have transcription factors, OCT4, SOX2, MYC changed half of what we know. These are Asifa Akhtar. There have been a number and Krüppel-like factor 4 (KLF4) — all natu- very exciting times. of important concepts that have emerged. rally expressed by ESCs — could achieve One that particularly jumps to mind is the this dramatic dedifferentiation of fibroblasts. Daniel St Johnston. Several surprising importance of epigenetics in gene regulation. This finding has allowed researchers to concepts have emerged during the past The field of epigenetics has flourished over derive patient-tailored iPS cells to study the decade: first, the amazing extent to which the past 10 years. It is clear that chromatin biology of a host of different human diseases basic cell biological processes have been provides an ideal platform for various post- — a first step, but a major one, for the future conserved during the evolution of eukary- translational modifications on DNA and development of new drugs and treatments otes; second, how much gene regulation is histones, which act as a signalling platform in medicine. post-transcriptional, particularly through for various cellular processes. I also think small non-coding RNAs; third, how basic that the discovery that a combination of Tim Mitchison. Reaction–diffusion gradi cellular processes, such as endocytic traffick- four transcription factors can induce a pluri ents specifying positional information ing, microtubule dynamics or mitochondrial potent state was phenomenal and has stimu inside cells. Gradients of signalling mol behaviour are modulated during the course lated a lot of research in the stem cell field1. ecules were long known in developmental of normal development; and last, the wide Last, but not least, the involvement of non- biology and paracrine physiology. But range of cell biological and developmental coding RNAs in various cellular and nuclear gradients inside cells being used as a spa- events that are regulated in response to processes is totally fascinating. The mecha- tial organizing system is a new concept. cellular stresses, such as DNA damage or nisms by which long non-coding RNAs Bicoid, a classic developmental morphogen, nutrient deprivation, and how these are used regulate gene expression await exciting diffuses inside a syncytium, but this is a as signals during normal development. discoveries in the coming years. special case. Gradients of RAN•GTP from The most important technical advances mitotic chromatin and of Aurora B activity have been high-throughput sequencing, Elaine Fuchs. For the stem cell field, there from chromatin in M phase and midzones in which has provided the complete sequence of is no question that the findings of Shinya cytokinesis are classic cellular signals that we many genomes, and the use of RNA interfer- Yamanaka and his co-worker Kazutoshi now know organize space inside cells using ence (RNAi) to knock down gene function.

The contributors* Asifa Akhtar obtained her bachelors degree in biology at University (PAR) proteins control the organization of the cytoskeleton, and how College London (UCL), UK, in 1993 and her Ph.D. in 1998 at the Imperial mRNAs are targeted to the correct positions within the cell. Cancer Research Fund in London, studying transcription regulation in Andreas Strasser is Joint Head of the Molecular Genetics of Cancer Division Richard Treisman’s laboratory. She continued in the field of chromatin at The Walter and Eliza Hall Institute of Medical Research in Melbourne, regulation as a postdoctoral fellow at the European Molecular Biology Australia. His research is focused on programmed cell death and how Laboratory (EMBL), Heidelberg, Germany, and the Adolf Butenandt defects in this process cause cancer or autoimmune disease and affect the Institute, Munich, Germany, in Peter Becker’s laboratory until 2001. response of tumour cells to anticancer therapy. Key discoveries have been: From 2001, she led her own research as a Group Leader at the EMBL. that abnormalities in cell death control can cause cancer or autoimmune In 2009, her laboratory moved to the Max Planck Institute of disease; that B cell lymphoma 2 (BCL‑2) and death receptors regulate Immunobiology and Epigenetics, Freiburg, Germany. Her laboratory distinct pathways to apoptosis; the pro-apoptotic BCL‑2 homology 3 primarily studies chromatin and epigenetic mechanisms, especially (BH3)-only proteins and that they are essential for initiation of programmed focusing on the regulation of the X chromosome by the phenomenon of cell death; that BCL‑2‑interacting mediator of cell death (BIM; also known dosage compensation in Drosophila melanogaster. In 2008, she received as BCL‑2L11) is required for negative selection of autoreactive thymocytes the European Life Science Organization (ELSO) award for significant and mature T cells; and that p53 upregulated modulator of apoptosis contribution in the field. (PUMA; also known as BBC3) and NOXA (also known as PMAIP1) are Elaine Fuchs is the Rebecca Lancefield Professor in Mammalian Cell essential for DNA damage-induced apoptosis mediated by the tumour Biology and Development at The Rockefeller University, New York, USA, suppressor p53. Current efforts include the development of antagonists and an investigator of the Howard Hughes Medical Institute (HHMI). of pro-survival proteins for cancer therapy. She has published >260 scientific papers and is internationally known Susan Taylor is an HHMI investigator at the University of California, for her research in the biology of skin stem cells and their role in normal San Diego (UCSD), USA, in the Departments of Pharmacology and tissue development and cancer. She is a member of the National Chemistry and Biochemistry. She received her Ph.D. in physiological Academy of Sciences, USA, and a foreign associate of the European chemistry from The Johns Hopkins University, Baltimore, Maryland, USA, Molecular Biology Organization (EMBO). Her honours include the working with Edward Heath. For her postdoctoral research, she worked first US National Medal of Science, the L’Oreal-UNESCO Award for with Brian Hartley at the Medical Research Council Laboratory of Molecular Women in Science and the Albany Medical Center Prize in Medicine Biology in Cambridge, UK, and then with Nathan Kaplan at UCSD. and Biomedical Research (shared with Shinya Yamanaka and James Her research focuses on the structure and function of protein kinases, in Thompson). She is immediate Past President of the International particular on cyclic AMP-dependent protein kinases, which serve as a Society for Stem Cell Research. prototype for the large protein kinase superfamily. She merges biophysics Tim Mitchison obtained a biochemistry degree at Oxford University, UK, and structural biology with cell biology and imaging to study not only the and then moved to the laboratory of Marc Kirschner for his Ph.D. thesis, structures of the protein kinase A (PKA) regulatory and catalytic subunits during which he purified tubulin from centrosomes and characterized but also the targeting of PKA to macromolecular complexes. the ‘dynamic instability’ that underlies microtubule growth. He started Claire E. Walczak is a Professor of Biochemistry and Molecular Biology in his own group at the University of California, San Francisco (UCSF), USA, the Medical Sciences Division at Indiana University, Bloomington (IUB), in 1988 and 9 years later moved to the systems biology department at Indiana, USA. She is also the Director of the IUB Light Microscopy Imaging Harvard Medical School, Boston, Massachusetts, USA. He became the Facility. She obtained her Ph.D. in biochemistry at the University of President of the American Society for Cell Biology in 2010. Wisconsin–Madison, USA, in 1993, followed by postdoctoral studies in cell Reuben J. Shaw, Ph.D., is a Hearst Endowment Assistant Professor and biology with Tim Mitchison at UCSF, before moving to Indiana in 1998. HHMI Early Career Scientist in the Molecular and Cell Biology Laboratory Her laboratory is interested in the regulation of microtubule dynamics at the Salk Institute for Biological Studies in La Jolla, California, USA. during mitosis. Her laboratory also studies the mechanisms by which cells His laboratory investigates how cancer and growth control are coupled achieve accurate chromosome segregation. with cellular and organismal metabolism. Their work focuses around the Marino Zerial graduated in biology at the University of Trieste, Italy, in LKB1–AMPK (AMP-activated protein kinase) signalling pathway, utilizing 1982 with a thesis on lysosomal storage disorders. He gained postdoctoral biochemistry, cell biology and genetic mouse models to decode this experience at the Institute J. Monod, Paris, France, on the organization of ancient pathway and how it is deregulated in cancer and type 2 diabetes. human genome and at the EMBL on the biosynthesis and endocytosis of Daniel St Johnston is the Director of the Wellcome Trust/Cancer Research transferrin receptor. He became an EMBL Research Group Leader in 1991, UK Gurdon Institute at the University of Cambridge, UK, and a Wellcome when he started his work on the molecular regulation of endocytosis, Trust Principal Research Fellow. He obtained his Ph.D. from Harvard focusing on the function of RAB GTPases. In 1998, he became Max Planck University in 1988, followed by a postdoctoral placement with Christian Director and co-founder of the Max Planck Institute for Molecular Cell Nüsslein-Volhard studying D. melanogaster axis formation. He has been Biology and Genetics (MPI-CBG), Dresden, Germany. a Group Leader at the Gurdon Institute since 1991, where his group investigates how cells become polarized, how partitioning-defective *Listed in alphabetical order.

Andreas Strasser. One important concept such as ligands of the tumour necrosis factor Moreover, the mechanism by which cas- to emerge is the ability to reprogramme dif- (TNF) family. In addition, an important result pase 8 prevents receptor-interacting protein 1 ferentiated cells, such as fibroblasts or hepato- has been the discovery that caspase 8 regu- (RIP1)‑ and RIP3‑mediated necroptosis is cytes, to assume a pluripotent stem cell fate. lates both apoptosis and another cell death now an area of immense interest. Another key finding has been the discovery process, termed necroptosis. It will now be that signal transducers undergo complex important to determine the roles of necrop- Susan Taylor. Genomic science has trans- processes of modification by different forms tosis in cell death processes that are thought formed the way we think about biology and of ubiquitin linkages and that these regulate to shape embryonic development but are not provides us with a new paradigm for asking cellular responses to extracellular signals, affected by mutations that block apoptosis. biological questions and for thinking about

evolution. Sequencing technology especially in combining biochemical and Finally, DNA sequencing is getting has advanced at an extraordinary pace, genomic analyses. In the future, I can cheaper by the day, and this will have a as has computing, so that sequencing whole foresee even more fruitful collaborations huge impact. If you can apply this resource genomes is becoming rapid and inexpen- between cell and molecular biologists and to your question, you will make rapid pro- sive. This has changed the face of biology. bioinformaticians or even physicists. In gress. It will also greatly enable work on The human microbiome and our dramatic fact, I think the next generation of scientists non-traditional organisms, which opens co-evolution with microbes is one of the are already on the way who will perform up all of biology for molecular cell biology most surprising discoveries to emerge both wet and dry laboratory research approaches. from genome science. In parallel, and also equally well. of comparable magnitude, is the recogni- R.J.S. There have been incredible break- tion of the role that small RNA molecules E.F. I find the interface between human throughs by technology-driven laboratories have and their enormous importance in genetics, cell biology and the pharmaceutical with expertise in physics, microscopy and regulating biology. and biotechnology industries to be the most mass spectrometry, which have revolu- exciting. The ability to rapidly sequence tionized the ability to detect and quantify Claire E. Walczak. The past 10 years have many human cancer samples has led to protein abundance, modifications and been remarkable in terms of our under- the identification of frequent mutations in interactions, as well as the concentrations standing of genome organization, chromatin particular types of cancer. The advances of intracellular metabolites that would have structure and gene expression, which pro- in small-molecule screening and design have been unimaginable 10 years ago. This has vide the foundation for specifying individual led to fruitful collaborations between basic also been coupled with advances in RNAi cell function. This information has also and pharmaceutical chemists, as they begin technology, DNA sequencing, ChIP–seq provided the basis for many genome-wide to design drugs that target only the mutant (chromatin immunoprecipitation followed studies looking at a multitude of biological form of the protein and not its wild-type by sequencing) and other techniques that processes and disease states. Such studies counterpart. An example is the recent devel- bring high-throughput approaches to cell have provided fundamental new insights opment of inhibitors against the Val600Glu biology laboratories. Collaborations among into epigenetics, have elucidated a molecular mutation in BRAF, a frequent mutation in adept practitioners using these disparate understanding of altered gene regulation in melanomas4,5. While tumour resistance still technologies to decode tissue-specific disease, and have enabled fundamental new makes eradication problematic, application regulators and rate-limiting pathway com- discoveries, such as RNAi and the existence of this approach to tumour resistance muta- ponents will uncover much fundamental of miRNAs in the genome. tions should lead to drugs that can overcome cell biology as well as new targets for many the tumour cell resistance. With a bit of different disease states. Marino Zerial. In the past decade, we vision towards the future, we can begin to have progressively shifted our view and imagine drug cocktails that will make many D. St J. Cell biological research is becoming approaches drastically towards a genomic more cancers treatable. increasingly quantitative, and this has stim- perspective. Today, our research of biological ulated exciting collaborations with mathe processes is no longer focused on single T.M. The development of new microscopy maticians and physicists in diverse areas, genes or proteins but tends to widen to the technology is currently extremely exciting, for example to measure forces in biological complexes, pathways or even systems level. and has been for two decades or more. This systems, to model morphogenetic events Owing to this change in dimensionality, includes new instrumentation, which typi- and to automate image analysis. Input we have ‘changed gear’ and routinely ben- cally involves physicists, and new probes, from the physical sciences has also played efit from comparing species, interrogating which often involves chemists. Super- an important role in the development of genomes and manipulating cells and organ- resolution is one exciting direction (photo- super-resolution microscopy, which has the isms. This was unthinkable in the 1990s. For activated localization microscopy (PALM), potential to revolutionize cell biology if and example, consider how RNAi has changed stochastic optical reconstruction micros- when it can be improved to image faster our approach to exploring the function of copy (STORM) and stimulated emission and deeper inside cells. genes. In general, the genomic revolution depletion (STED))6–8. Activity biosensors is has disclosed a horizon of interesting prob- another2,3. Intravital imaging in mice and A.S. Interactions between bioinformati- lems, such as the role of both coding and humans is yet another. cians and cellular and molecular biologists non-coding RNAs, to name one. The success of mathematical modelling have been highly productive, for example has been more mixed. I am optimistic that by allowing one to make sense out of large There has been increasing collaboration it will help us truly understand collective data sets, such as gene expression profiles. between different research communities protein behaviour in the future but, so far, Interactions between structural biologists, both within, and outside, cell biology. Where I think the impact has been modest. One big medicinal chemists and cell biologists have do you think the most interesting interfaces in problem is groups saying, “Our model works, allowed us to define complex interactions molecular cell biology reside, and what do you therefore we have solved the problem”. This is of proteins in cell signalling, such as the envisage the most fruitful collaborations will rarely true, and questionable assumptions are functions of the B cell lymphoma 2 (BCL‑2) be in the future? often hidden. But we do know that human family members in apoptosis. Importantly, intuition alone cannot explain collective such interdisciplinary interactions have A.A. Indeed, in this post-genomic era, protein behaviour in complex systems, and facilitated the development of small mol the way we do research has changed dra- there seems to be no alternative to formal ecules to manipulate these processes in a matically. On average, papers have a more modelling. But, we do have to get it better therapeutic setting, such as the treatment interdisciplinary and collaborative flavour, integrated and be more critical. of certain cancers.

S.T. Building bridges between computational A.A. The dynamics and quantitative nature the astonishing array of different cell types science and experimental biology is one of of how various pathways and macro with specialized functions that occur our great opportunities and also one of our molecular complexes function remain in vivo. I think that one of the key challenges greatest challenges. There are enormous poorly understood. We are also beginning for the future is to develop better ways of opportunities for bridging biology with to appreciate that spatial and temporal con- performing in vivo cell biology to examine theory and computer science, as well as with trol contribute important regulatory steps cellular behaviours in the context of organs translational medicine. Advances in com- in gene regulation. The same molecule in and tissues. The ability to induce iPS cells to puting have allowed us to gather enormous different cellular compartments may form organs in culture will be an enormous amounts of data; however, the relevance of have very different regulatory functions, help for this type of work. the data is compromised without a mech which could be missed during biochemi- anistic understanding of biological systems. cal analyses. If we can gear our research to A.S. One challenge is elucidating the precise It is absolutely essential to bring these com- go from qualitative to quantitative biology definition of how cellular differentiation munities together so that we find ways to and understand the real dynamics of our and functional activation are controlled; truly speak a common language. Only in this favourite molecules in vivo, we will make a that is, how the many transcriptional regu- way can we achieve a comprehensive view of great leap in our understanding of various lators, modifications to the genome (for biological systems. cellular pathways. example, through methylation) and post- transcriptional regulatory processes (for C.E.W. Even only 10 years ago, cell biology E.F. The most pressing questions in my field example, through the impact of miRNAs) was largely a ‘fuzzy’ science, in which we are in many ways no different than they interact to regulate stepwise changes looked at pretty pictures and described what were 20–30 years ago, but the answers are towards a differentiated state. Another is we saw. Quantitative approaches, aided by closer at hand. How do stem cells build tis- defining the mechanisms that regulate non- advances in imaging, have transformed sues during normal homeostasis and wound apoptotic, but still genetically programmed, the field to a more quantitative science. repair, and how does this go awry in human cell death pathways and the definition of The development of mathematical models diseases, including cancers? And how can their role in normal physiology (for exam- for biological processes has grown increas- we exploit this information to understand ple, during embryonic development and ingly more complex, offering new insight the bases of these different diseases and tissue homeostasis in adulthood). into protein function. In the future, we need develop new and improved therapies for to increase collaboration with chemists the treatment of these disorders? With the S.T. The biggest challenge for biology is and physicists utilizing nanotechnology to recombinant DNA technology revolution of always to ask the right question, and this visualize and perturb proteins on smaller the early 1980s and the human genome rev- is even more important now as techno and smaller scales. Computer scientists are olution at the turn of the century, the inter- logies advance so rapidly. In our frenzy essential to help us organize, process and face between basic science and medicine is to collect more and more data, we need to analyse the large datasets being generated by closing at a pace we never imagined possible learn how to ask the right questions and high-throughput methods. as students. The tools and technologies how to extract useful information from available to address fundamental biological that data. In parallel with systems biology, M.Z. Biological research today makes use of questions are advancing at a ferocious rate. we must have a mechanistic understand- more quantitative approaches than before. The challenge ahead will be to ask the right ing of biology. Without understanding the For example, imaging and image analysis can questions and creatively develop strategies underlying biochemical principles, the data be very quantitative, sensitive and precise, and that exploit these tools to bridge this gap mean little. Just as we need classical physiol- thus are tremendously powerful for explor- and revolutionize medicine. ogy to understand how molecules work in ing biological mechanisms in time and space. whole animals, we need biochemistry to This makes the collaboration with theor R.J.S. A big challenge going forward comes have a true mechanistic understanding of eticians particularly productive. Biologists out of this explosion of data from different biological events. need to work with mathematicians, physicists systems: bridging the omics studies (RNAi and engineers interested in biological prob- screens, ChIP–seq, phosphoproteomes and C.E.W. While the genomic revolution has lems because they can help us to understand mass spectrometry interactomes) to define provided us with a wealth of potentially mechanisms in a more precise and predictive what the key rate-limiting proteins in any important molecules, the large-scale func- fashion. Previously, our problem was the abil- biological process are. The world still needs tional genomics screens only scratch the ity to identify some components that could careful mechanistic dissection of individual surface of understanding the mechanisms give us clues into molecular mechanisms. proteins and functions, which sometimes by which these proteins act. The challenge is Now that we can get to such components gets lost amidst the push for larger and to develop creative approaches to answer the relatively easily (for example, with ‘omics’), larger datasets. Taking the findings in cellu most fundamental biological questions. For our problem becomes how to understand the lar systems and then bridging that to the example, although proteomic approaches ways in which the structure and functional physiology and pathology of diseases in have identified all of the components of the properties of biological systems emerge from the intact higher organism also remains a mitotic spindle and genome-wide screens the interplay of individual components. For key challenge. have identified an array of molecules that this, we need the support of theory. affect the mitotic spindle, we still do not D. St J. Most recent cell biology has focused understand the fundamental mechanism What, in your view, are the most on a relatively small number of cell types by which each chromosome moves to the pressing questions and key challenges (most often, unpolarized, transformed tis- spindle equator and then is partitioned to for cell biologists moving forward? sue culture cells) and has largely overlooked the daughter cells.

M.Z. Cell biology must move to tissues into cures. I am optimistic that we can do D. St J. Apart from the usual ones of too and organisms. An outstanding problem so, and I would encourage young research- much bureaucracy and too little funding, is bridging between scales. Understanding ers to be optimistic as well, to pursue their one of the major difficulties we face in the how cellular components form complexes, passion for science but also to become laboratory is how to examine the functions how these assemble into organelles and how involved in efforts to communicate with of proteins that have multiple roles in the organelles form cells, which build organs policy makers and the public who hold the same cell lineage. Although there are a few and organisms, poses enormous technical strings to our future. specific tricks that allow one to knock out and conceptual challenges. The integra- the function of a protein at a specific place tion of biological processes is one of the T.M. Funding is a major bottleneck every or time, most of these actually knock out most difficult problems we face. Solving where, and it particularly affects young the gene and not the protein, leaving the these problems requires trespassing across scientists. One huge challenge is proving problem of perdurance. It would be a huge the traditional borders between fields and our worth to society, which we must do if help to have a standard way of engineering developing new experimental and analytical we expect to be funded by taxpayers’ money. conditional mutant forms of proteins that methods. At present, we can explain only The huge progress in molecular cell biology are either light or heat sensitive. small parts of biological mechanisms: we see in the past two decades has not translated My advice to young scientists is to not a few pieces of a puzzle, but for the whole into a whole lot of improvement in the assume that everything that has been pub- picture we must draw in complexity. There human condition — for example, new ways lished is correct and that it is better to tackle are no current solutions at the modelling or of preventing and treating disease. I believe interesting questions that are hard than computational level. This problem requires basic science is having, and will have, that minor questions that are easy. the development of new theories. impact, but over long time periods and, often, in unpredictable ways. Solving this A.S. First, I believe that it is important to What would you consider to be the problem requires that some bright young work on a problem that you are passionate main bottlenecks for the productivity people (but not all — basic progress is about (that is, for which you really, really of your research and what advice would you as important as ever) take the road of: want to be the first to know the answers). give to young researchers facing these first, translating basic research into useful Second, it is a great joy to work in an envi- challenges? applications, which in my mind includes ronment that is highly collaborative and col- synthetic biology as well as more conven- legial. Nobody can cover all areas of expertise A.A. Despite technical advances, such as tional ideas like drugs and stem cell-based that are necessary to tackle ‘big issues’. high-throughput sequencing strategies, organ replacements; and second, educating Therefore, having ready access, as a cellular which have been tremendous in providing and energizing the public, which includes or molecular biologist, to structural biologists us with a global view relatively rapidly, the innovating at all stages of conventional edu- and bioinformaticians who are eager to real bottleneck remains the in-depth analy- cation as well as public outreach, political collaborate is a great boost for your ability sis of data from these strategies and how to action and internet-based science activity. to answer important questions. Finally, when make biological sense out of such informa- My advice to young scientists is to avoid choosing your postdoctoral position, it is in tion. I also think the challenge remains to the road well travelled. There is no sure- my opinion a good idea to join a group that understand how various biological path- fire route to success in sciences. But if you desperately needs your expertise and has ways work mechanistically and, even more take the common road of doing what your projects and/or techniques on offer that you importantly, how various pathways are advisor and her colleagues already do, you want to learn. This will create a mutually interconnected. These are challenges for all are guaranteed to end up in a crowded field beneficial or ‘symbiotic’ relationship, whereas generations of scientists. For young labora in which it is hard to compete for resources joining a research programme that already tories, one of the major challenges is to and gain independent recognition. You need has all the expertise that you can offer is like hire the right group of people and to focus to take risks — in approach, in system and ‘shipping coals to Newcastle’. on a particular biological question. My in questions. advice would be to use a multidisciplinary S.T. Formulate your questions carefully and approach to address the questions of inter- R.J.S. Ironically, in the face of the kinds then delve deeply into your system. Do not est, as this provides one with the possibility of technologies that have been developed be afraid of collaborations and of learning to look at the question from different angles for cost-effective RNAi screens and full new technologies and new systems. Do not and may reveal unexpected and exciting proteomic mass spectrometry analyses of fear reaching out. A major bottleneck for all findings. all cellular proteins and metabolites, one biological research in the United States now is unmet need that is still rate-limiting in funding of RO1 investigator-initiated grants. E.F. In the United States, the main bottle- nearly every area of cell biology research The US National Institutes of Health have neck is the precarious funding climate we is having tools and reagents that can selec- nurtured an explosion of biological discover- face and the diminished emphasis our coun- tively visualize pools of a given protein with ies over the past few decades, and these dis- try places on higher education. Our country specific post-translational modifications coveries are having an enormous, and often has spent decades investing in biomedical (for example, acetylation, sumoylation unanticipated, impact on our understanding research and we are now poised to capital- and phosphorylation) in intact cells and of disease. We have, unquestionably, been ize on this foundation and make major organisms. My advice to young scientists the dominant player in the international breakthroughs in the coming decades. It is would be to explore areas at those interfaces community. Other countries, however, are paramount that we work harder to educate between fields and always be incorporating now outpacing us in their funding and we policy makers and the public about the time new techniques and ways of thinking about will have trouble maintaining our eminence it takes to translate scientific discoveries a biological problem. and dominance.

C.E.W. Carrying out studies that will have a Andreas Strasser is at the Molecular Genetics of sustained impact requires an ever-increasing Cancer Division, The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, amount of multidisciplinary resources, Melbourne, Victoria 3050, Australia. including people, expertise, equipment and e‑mail: [email protected] funding. Our educational system is not keep- Susan Taylor is at the Howard Hughes Medical ing pace with the rapid development of new Institute, Chemistry/Biochemistry & Pharmacology, technologies and still maintains fairly tradi- University of California, San Diego, tional disciplines. This makes it challenging Leichtag 415, 9500 Gilman Drive, La Jolla, California 92093–0654, USA. to recruit young scientists who are willing to e‑mail: [email protected] break new ground to make the exciting new discoveries. My advice to young research- Claire E. Walczak is at Medical Sciences, Indiana University, 915 E. 3rd St., Myers Hall 262, ers is to take every opportunity available to Bloomington, Indiana 47405, USA. learn and discover, and never forget to take e‑mail: [email protected] time to just think and reflect about what is Marino Zerial is at the Max Planck Institute for interesting and cool. Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstrasse 108, 01307 Dresden, Germany. M.Z. My strong advice to young researchers e‑mail: [email protected] is to think in a truly multidisciplinary way doi:10.1038/nrm3187 and to go to institutes which can support 1. Takahashi, K. & Yamanaka, S. Induction of pluripotent this approach. Addressing a problem from stem cells from mouse embryonic and adult fibroblast cultures by defined factors. Cell 126, 663–676 different sides is essential. Good funding (2006). is not everything: I would also encourage 2. Kalab, P., Weis, K. & Heald, R. Visualization of a Ran-GTP gradient in interphase and mitotic Xenopus young scientists to choose institutes where egg extracts. Science 295, 2452–2456 (2002). they can get good mentoring and be stimu- 3. Fuller, B. G. et al. Midzone activation of Aurora B in anaphase produces an intracellular phosphorylation lated and challenged by faculty members gradient. Nature 453, 1132–1136 (2008). who demonstrate true interest in their work. 4. Chapman, P. B. et al. Improved survival with vemurafenib in melanoma with BRAF V600E Importantly, treasure the value of central mutation N. Engl. J. Med. 364, 2507–2516 (2011). facilities, available to everyone and capable 5. Nazarian, R. et al. Melanomas acquire resistance to B‑RAF(V600E) inhibition by RTK or N‑RAS of supporting research beyond what a sin- upregulation. Nature 468, 973–977 (2010). gle laboratory can do. This kind of support 6. Klar, T. A. et al. Fluorescence microscopy with diffraction resolution limit broken by stimulated raises the level of ambition and productivity emission. Proc. Natl Acad. Sci. USA 97, 8206–8210 of a young starting group more than any (2000). 7. Betzig, E. et al. Imaging intracellular fluorescent seemingly rich ‘start-up package’. proteins at nanometer resolution. Science 313, 1642–1645 (2006). Asifa Akhtar is at the Max Planck Institute of 8. Rust, M. J., Bates, M. & Zhuang, X. Sub‑diffraction‑ Immunobiology and Epigenetics, Stübeweg 51, limit imaging by stochastic optical reconstruction D‑79108 Freiburg, Germany. microscopy (STORM). Nature Methods 3, 793–796 e‑mail: [email protected] (2006).

Elaine Fuchs is at The Rockefeller University, Competing interests statement Howard Hughes Medical Institute, The authors declare no competing financial interests. 1230 York Avenue BOX 300, New York, New York 10065, USA. FURTHER INFORMATION e‑mail: [email protected] Asifa Akhtar’s homepage: http://www3.immunbio.mpg.de/ research-groups/chromatin-regulation/laboratory-asifa-akhtar Tim Mitchison is at the Department of Systems Elaine Fuch’s homepage : Biology, Harvard Medical School, 200 Longwood, http://lab.rockefeller.edu/fuchs Tim Mitchison’s homepage : WA 536, Boston, Massachusetts 02115, USA. http://mitchison.med.harvard.edu e‑mail: [email protected] Reuben J. Shaw’s homepage: http://www.salk.edu/faculty/shaw.html Reuben J. Shaw is at the Salk Institute for Biological Daniel St Johnston’s homepage : Studies, 10010 North Torrey Pines Road, http://www.gurdon.cam.ac.uk/~stjohnstonlab La Jolla, California 92037, USA. Andreas Strasser’s homepage: http://www.wehi.edu.au/ e‑mail: [email protected] faculty_members/professor_andreas_strasser Susan Taylor’s homepage : Daniel St Johnston is at The Wellcome Trust/Cancer http://susantaylorlab.ucsd.edu Research UK Gurdon Institute, The Henry Wellcome Claire E. Walczak’s homepage : http://mypage.iu.edu/~walczak Building of Cancer and Developmental Biology, Marino Zerial’s homepage : http://www.mpi-cbg.de/ University of Cambridge, Tennis Court Road, research/research-groups/marino-zerial.html Cambridge CB2 1QN, UK. ALL LINKS ARE ACTIVE IN THE ONLINE PDF e‑mail: [email protected]