Ruminations on twenty-five years of Patricia Hill Collins's Black Feminist Thought: Knowledge,Consciousness and the Politics of Empowerment

My review focuses on the impact that Black Feminist Thought has had on my personal and professional life. I weave together lessons I have learned from Patricia Hill Collins with reflections on my own lived experience – from my family of origin to college experiences to my work as the founding director of the Collegium of Black Women Philosophers.     

Alterations in hypertensive arteries

Mentoring in academia is often carried out in an informal way depending on individuals and circumstances. I was quite fortunate to make the acquaintance of Professor E.E. Daniel when I was making a transition from my research in entomology to biomedical sciences. Here I recount some of that experience, and describe some of the lessons I have learned from this experience, as my tribute to Dr. Daniel on the occasion of his 80th birthday.     

The Chemical Synthesis of DNA/RNA: Our Gift to Science

It is a great privilege to contribute to the Reflections essays. In my particular case, this essay has allowed me to weave some of my major scientific contributions into a tapestry held together by what I have learned from three colleagues (Robert Letsinger, Gobind Khorana, and George Rathmann) who molded my career at every important junction. To these individuals, I remain eternally grateful, as they always led by example and showed many of us how to break new ground in both science and biotechnology. Relative to my scientific career, I have focused primarily on two related areas. The first is methodologies we developed for chemically synthesizing DNA and RNA. Synthetic DNA and RNA continue to be an essential research tool for biologists, biochemists, and molecular biologists. The second is developing new approaches for solving important biological problems using synthetic DNA, RNA, and their analogs.     

Teaming up: from motors to people

When I reflect on how I became a cell biologist and why I love being one today, one thing that comes to mind is the many terrific collaborations I have had. The science I am most proud of from my graduate and postdoctoral training would not have been possible without working in teams with other scientists. Now, in my own group, much of our best work is being done collaboratively, both within the lab and with other labs. In this essay, I will highlight my experiences working in teams as a trainee, the role teamwork has played in my own research group, and how important I think collaborative science is for the future of biological research.     

Establishing an academic laboratory: mentoring as a business model

It is a tremendous honor for my group and me to receive the recognition of the 2014 Women in Cell Biology Junior Award. I would like to take the opportunity of this essay to describe my scientific journey, discuss my philosophy about running a group, and propose what I think is a generalizable model to efficiently establish an academic laboratory. This essay is about my view on the critical components that go into establishing a highly functional academic laboratory during the current tough, competitive times.     

Romancing mitosis and the mitotic apparatus

One of the earliest lessons students learn in biology is the process of mitosis and how cells divide to produce daughter cells. Although first described more than a century ago by early investigators such as E. B. Wilson, many aspects of mitosis and cell division remain the subject of considerable research today. My personal investigations and research contributions to the study of mitosis were made possible by recent developments in the field when I began my career, including access to novel mammalian cell culture models and electron and fluorescence microscopy. Building upon those innovations, my laboratory and other contemporary investigators first charted the ultrastructure and molecular organization of mitosis and chromosome movement and the assembly and function of the cytoskeleton. This field of research remains a significant challenge for future investigators in cell biology and medicine.     

Proteostenosis and plasma cell pathophysiology

Plasma cells differentiate from B lymphocytes to sustain antibody production. As professional secretors, they allow dissecting proteostasis in the exocytic compartment, the stresses that protein production entails and their possible roles in signaling. Most plasma cells are short-lived to limit antibody responses. After a few days of intense immunoglobulin production, they undergo apoptosis, offering a unique model of cellular senescence. Recent observations reveal that proteotoxic stresses physiologically contribute to regulate their biogenesis, function and lifespan, explaining partly the sensitivity of multiple myeloma cells to proteasome inhibitors. This essay summarizes these plasma cell lessons, and their general implications for the regulation of proteostasis, cell senescence and cancer therapeutics.     

From Chloroplasts to Chaperones: How One Thing Led to Another

Two lessons I have learned during my research career are the importance of following up unexpected observations and realizing that the most obvious interpretation of such observations can be rational but wrong. When you carry out an experiment there is usually an expectation that the result will fall within a range of predictable outcomes, and it is natural to feel pleased when this turns out to be the case. In my view this response is a mistake. What you should be hoping for is a puzzling result that was not anticipated since with persistence and luck further experiments may uncover something new. In this article I give a personal account of how studies of the synthesis of proteins by isolated intact chloroplasts from pea leaves eventually led to the discovery of the chaperonins and the formulation of the general concept of the molecular chaperone function that is now seen to be a fundamental aspect of how all cells work.     

What does it take to get the job done?

I am extremely honored to be the recipient of the 2015 Women in Cell Biology Junior Award. When I reflect on my journey in science, many great people and memorable experiences come to mind. Some of these encounters were truly career-defining moments. Others provided priceless lessons. In this essay, I recount some of the moments and experiences that influenced my scientific trajectory with the hope that they may inspire others.     

Membranes,viruses, detergents,and endosomes

The fluid mosaic model for biological membranes was formulated 40 years ago. Ten years later endosomes were discovered as important prelysosomal organelles. At the outset of my research career, I was fortunate to witness both these turning points in biochemistry and cell biology from close up, and to participate in some of the studies. In this short essay, I will describe how this came about, and also try to provide some background as to the general starting situation in those not so distant pioneering years of membrane biology.     

A different kind of quarterback

I am not big on celebrations, nor do I accept many invitations to receive awards. There is much work to be done, and the reward is in the doing. I learned this lesson early from my parents, Martha and Robert Guyden. However, I am humbled that anyone would even mention my name in association with E. E. Just. I, like he, was born into a segregated America, and somehow we both found biology. I think Just's life story instigates a discussion on diversity in science, as well it should. However, after reading Tyrone Hayes' (2010 E. E. Just Award recipient) essay from last year, "Diversifying the Biological Sciences: Past Efforts and Future Challenges" (Hayes, 2010), I have little to add on the subject. His words gave voice to my thoughts. That being said, I would like to use these pages to describe my journey into the "Cell" and the people who "hoed the row ahead of me."     

Mind molecules

Scientific styles vary tremendously. For me, research is largely about the unfettered pursuit of novel ideas and experiments that can test multiple ideas in a day, not a year, an approach that I learned from my mentor Julius "Julie" Axelrod. This focus on creative conceptualizations has been my métier since working in the summers during medical school at the National Institutes of Health, during my two years in the Axelrod laboratory, and throughout my forty-five years at Johns Hopkins University School of Medicine. Equally important has been the "high" that emerges from brainstorming with my students. Nothing can compare with the eureka moments when, together, we sense new insights and, better yet, when high-risk, high-payoff experiments succeed. Although I have studied many different questions over the years, a common theme emerges: simple biochemical approaches to understanding molecular messengers, usually small molecules. Equally important has been identifying, purifying, and cloning the messengers' relevant biosynthetic, degradative, or target proteins, at all times seeking potential therapeutic relevance in the form of drugs. In the interests of brevity, this Reflections article is highly selective, and, with a few exceptions, literature citations are only of findings of our laboratory that illustrate notable themes.     

Adenosine: old passion, new perspectives

In this review is summarized my research in the adenosine field from the beginning of my carrier to day. My research began preparing the degree thesis with Prof. Carlo Alfonso Rossi, about the purification and characterization of adenosine deaminase. My scientific interest for adenosine has spread during the years and I have been interested in the study of ARs and their related transduction and in the study of molecular mechanisms involved in homologous and heterologous AR receptor regulation.     

Differences in the expression of human class I MHC alleles and their associated peptides in the presence of proteasome inhibitors

We have studied the contributions of proteasome inhibitor-sensitive and -insensitive proteases to the generation of class I MHC-associated peptides. The cell surface expression of 13 different human class I MHC alleles was inhibited by as much as 90% or as little as 40% when cells were incubated with saturating concentrations of three different proteasome inhibitors. Inhibitor-resistant class I MHC expression was not due to TAP-independent expression or preexisting internal stores of peptides. Furthermore, it did not correlate with the amount or specificity of residual proteasome activity as determined in in vitro proteolysis assays and was not augmented by simultaneous incubation with multiple inhibitors. Mass spectrometry was used to directly characterize the peptides expressed in the presence and absence of proteasome inhibitors. The number of peptide species detected correlated with the levels of class I detected by flow cytometry. Thus, for many alleles, a significant proportion of associated peptide species continue to be generated in the presence of saturating levels of proteasome inhibitors. Comparison of the peptide-binding motifs of inhibitor-sensitive and -resistant class I alleles further suggested that inhibitor-resistant proteolytic activities display a wide diversity of cleavage specificities, including a trypsin-like activity. Sequence analysis demonstrated that inhibitor-resistant peptides contain diverse carboxyl termini and are derived from protein substrates dispersed throughout the cell. The possible contributions of inhibitor-resistant proteasome activities and nonproteasomal proteases residing in the cytosol to the peptide profiles associated with many class I MHC alleles are discussed.     

Proteasome inhibitor lactacystin augments natural killer cell cytotoxicity of myeloma via downregulation of HLA class I

Modulation of inhibitory and activating natural killer (NK) receptor ligands on tumor cells represents a promising therapeutic approach against cancer, including multiple myeloma (MM). Human leukocyte antigen (HLA) class I molecules, the NK cell inhibitory killer cell immunoglobulin-like receptor (KIR) ligands, are critical determinants of NK cell activity. Proteasome inhibitors have demonstrated significant anti-myeloma activity in MM patients. In this study, we evaluated the effect of proteasome inhibitors on the surface expression of class I in human MM cells. We found that proteasome inhibitors downregulated surface expression of class I in a dose- and time-dependent manner in MM cell line and patient MM cells. No significant changes in the expression of the MHC class I chain-related molecules (MIC) A/B and the UL16-binding proteins (ULBPs) 1–3 were observed. Downregulation of class I by lactacystin (LAC) significantly enhances NK cell-mediated lysis of MM. Furthermore, the downregulation degree of class I was associated with increased susceptibility of myeloma cells to NK cell killing. HLA blocking antibody produced results that were similar to the findings from proteasome inhibitor. Taken together, our data suggest that proteasome inhibitors, possible targeting inhibitory KIR ligand class I on tumor cells, may contribute to the activation of cytolytic effector NK cells in vitro, enhancing their anti-myeloma activity. Our findings provide a rationale for clinical evaluation of proteasome inhibitor, alone or in combination, as a novel approach to immunotherapy of MM.     

Proteotoxic crisis,the ubiquitin-proteasome system,and cancer therapy

Genomic alterations may make cancer cells more dependent than normal cells on mechanisms of proteostasis, including protein folding and degradation. This proposition is the basis for the clinical use of proteasome inhibitors to treat multiple myeloma and mantle cell lymphoma. However, proteasome inhibitors have not proved effective in treating other cancers, and this has called into question the general applicability of this approach. Here, I consider possible explanations for this apparently limited applicability, and discuss whether inhibiting other broadly acting components of the ubiquitin-proteasome system - including ubiquitin-activating enzyme and the AAA-ATPase p97/VCP - might be more generally effective in cancer therapy.     

Being at the right place at the right time

I am tremendously honored to receive the 2012 Women in Cell Biology Junior Award. In this essay, I recount my career path over the past 15 years. Although many details are specific to my own experiences, I hope that some generalizations can be made to encourage more women to pursue independent scientific careers. Mine is a story of choosing a captivating question, making the most of your opportunities, and finding a balance with life outside the lab.It is a great honor to have been awarded the 2012 Women in Cell Biology Junior Award from the ASCB. Looking back at the 15 years I have spent doing research in cell biology, my overwhelming feeling is that it has been and still is a lot of fun. I am extremely fortunate to have a job that I truly enjoy and that gives me complete intellectual freedom. My lab choices over the years were motivated by scientific curiosity and enthusiasm for new environments and topics, rather than by career building. It is thus truly amazing to be rewarded for (rather a lot of) work enjoyed.     

Again,What the Philosophy of Biology is not

There are many things that philosophy of biology might be. But, given the existence of a professional philosophy of biology that is arguably a progressive research program and, as such, unrivaled, it makes sense to define philosophy of biology more narrowly than the totality of intersecting concerns biologists and philosophers (let alone other scholars) might have. The reasons for the success of the “new” philosophy of biology remain poorly understood. I reflect on what Dutch and Flemish, and, more generally, European philosophers of biology could do to improve the situation of their discipline locally, regionally, and internationally, paying particular attention to the lessons to be learned from the “Science Wars.” This paper grew out of my contribution to the symposium Philosophy of Biology in the Netherlands and Flanders organized by Thomas Reydon and Sabina Leonelli in Amsterdam in February 2004. It is a rather personal reaction to many of the opinions voiced in the quite heated atmosphere of the Symposium. My main concern is to convey an idea of what, according to me, is required to turn “our” philosophy of biology into a more successful enterprise than it currently is. This is motivated by a disconcerting discovery I made at the Symposium: Contrary to my expectations, a sensitivity for the sorts of things that make possible philosophy of biology of the best kind available today seems to be largely lacking in our part of the world. I wish to stress from the outset that although I will be quite polemical at times, this is always intended in the spirit of constructive dialogue.