ABSTRACT
First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Sweksha Lohani is first author on ‘ A novel role for PRL in regulating epithelial cell density by inducing apoptosis at confluence’, published in JCS. Sweksha is a postdoctoral researcher in the lab of Hiroaki Miki at Department of Cellular Regulation, Osaka University, Japan, investigating the physiological role of PRL in epithelial homeostasis.
Sweksha Lohani
How would you explain the main findings of your paper in lay terms?
Epithelia, such as those lining the surface of the intestine, are a sheet-like structure composed of epithelial cells tightly connected with each other. The cell density of the epithelial sheet is maintained exquisitely constant, which is indispensable for the survival of multicellular organisms. One of the well-known mechanisms to regulate epithelial cell density is by elimination of excessive cells through induction of cell death; however, the mechanistic details are poorly understood. In this study, we found that PRL (phosphatase of regenerating liver), a membrane-anchored protein previously known for its role in cancer malignancy, regulates epithelial cell density through density-dependent induction of cell death in the non-cancerous normal epithelial cells. We have obtained consistent results using both cultural epithelial cells and zebrafish embryos. In addition, we showed that this role of PRL is important in ‘convergent extension’, an early developmental process common in vertebrates. Overall, we found an important role for PRL in the vertebrate epithelium.
Were there any specific challenges associated with this project? If so, how did you overcome them?
I faced several challenges while carrying out this research. Experiments using stretching chambers to artificially reduce the cell density, radio-labeling of newly synthesized proteins and zebrafish experiments were all not common experiments performed in our lab, and therefore I had to optimize all the experimental setups. Not only finding and optimizing suitable tools or antibodies, but also learning new techniques and knowledge were required. To overcome these challenges, I have read many papers and also consulted knowledgeable people both within and outside of my lab.
When doing the research, did you have a particular result or ‘eureka’ moment that has stuck with you?
One of the ‘eureka’ moments was when I noticed the visual difference between control cells and PRL-expressing epithelial MDCK cells at confluence; PRL-expressing cells had no ‘domes’, fluid-filled swollen structures characteristic for well-polarized confluent epithelia. This observation was a starting point, and I am glad that we could develop our research and are now able to give some answers to how cell density is exquisitely homeostatic in the epithelium.
Why did you choose Journal of Cell Science for your paper?
Journal of Cell Science is a prestigious journal that covers all aspects of cell biology and is attracting the attention of broad audiences. We thought that our research topic fits the scope of this journal very well, and we could convey our findings to a wide audience.
Cell density-dependent induction of cell death in PRL-expressing epithelial MDCK cells. (A) Schematic illustration showing mechanical stretch of epithelial cell sheet cultured in silicon chamber. (B) Indicated cells were treated with doxycycline (Dox) and epithelial cell sheet was stretched as in (A). The cells were stained with anti-cleaved caspase-3 antibody (red) and DAPI (blue), and observed under a confocal microscope. The signal of GFP (green) indicates doxycycline inducible expression of PRL. Scale bar: 100 µm.
Cell density-dependent induction of cell death in PRL-expressing epithelial MDCK cells. (A) Schematic illustration showing mechanical stretch of epithelial cell sheet cultured in silicon chamber. (B) Indicated cells were treated with doxycycline (Dox) and epithelial cell sheet was stretched as in (A). The cells were stained with anti-cleaved caspase-3 antibody (red) and DAPI (blue), and observed under a confocal microscope. The signal of GFP (green) indicates doxycycline inducible expression of PRL. Scale bar: 100 µm.
Have you had any significant mentors who have helped you beyond supervision in the lab? How was their guidance special?
I had a hard time optimizing experimental setups. During those times, I got words of encouragement from Professor Hiroaki Miki and Dr Yosuke Funato of my current lab, which helped me to continue my research without being intimidated.
What motivated you to pursue a career in science, and what have been the most interesting moments on the path that led you to where you are now?
I enjoyed learning about the world of science from my childhood, probably due to some influence from my father, who is a researcher. In the beginning, I was fascinated by the fact that although our body orchestrates different activities unconsciously, we still don't have all the answers to explain them. During my undergraduate studies, I majored in Human Biology, where I developed a keen interest in cell biology, especially in terms of cancer. Even though morbidity associated with cancer is high world-wide, the pathophysiology of every cancer is not known. Therefore, I then decided to pursue my career in basic cell biology research during my masters and PhD. To date, the most interesting moments for me have been when presenting my findings at the conferences and getting comments like ‘this is very interesting’, as well as winning prizes.
Who are your role models in science? Why?
I don't have a particular role model, but I admire those scientists who have interests in and a curiosity about different fields (not limited to science) and enjoy science from the bottom of their heart. After all, sometimes flexible mindsets and toughness are essential to pursue research that might add or change the pre-existing concepts.
What's next for you?
I am currently working as postdoctoral researcher and hope to continue my career in academia, preferably in the field of cell biology.
Tell us something interesting about yourself that wouldn't be on your CV
I love swimming, playing badminton and appreciating paintings. All of these are relaxing and good when I need a break. To talk about paintings makes me more creative and helps to make attractive slides for scientific presentations.
Sweksha Lohani's contact details: Department of Cellular Regulation, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan.
E-mail: [email protected]
