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. Tejeshwar Rao is first author on ‘EGFR activation attenuates the mechanical threshold for integrin tension and focal adhesion formation’, published in JCS. Tejeshwar is a postdoctoral researcher in the lab of Dr Alexa Mattheyses at the Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, where he is investigating the forces, dynamics and protein interactions within macromolecular assemblies central to inter- and intra-cellular communication using novel and advanced fluorescence microscopy.

Tejeshwar Rao

How would you explain the main findings of your paper in lay terms?

Cells respond specifically and dynamically to signals from the environment outside the cell, and dysregulation of these signals leads to a variety of diseases. Therefore, it is important to decipher the role of specific inputs that regulate mechanical signals and understand how signals are interpreted and responded to. Epidermal growth factor receptor (EGFR) is one such cell membrane receptor that controls signaling in cells, regulating growth, death, development, movement and attachment. When a cell wants to attach to any surface, it forms contact sites (focal adhesions) while generating force (tension) using the membrane protein integrin. Here, we explored the influence of EGFR on the process of integrin attachment and tension generation using smartly designed tension gauging surfaces (tension gauge tethers – TGTs). These TGTs consist of a DNA duplex attached to the coverslip surface by one strand and presenting the ligand on the other. The probe opens when cells apply a strong force to capture the ligand, which is then recorded as a fluorescent signal. Using this setup, we observed that EGFR acts as a ‘mechano-organizer’ that tunes the process of integrin tension generation, allowing cells to attach and spread by influencing focal adhesion distribution and maturity. Our results provide evidence suggesting growth factors in general are important regulators of cell mechanics.

Were there any specific challenges associated with this project? If so, how did you overcome them?

One of the main challenges of this project were the rescue experiments performed following EGFR siRNA knockdown. This was particularly difficult given the sequence that needed to be followed and the timeline for performing the entire experiment. It first required knocking down the protein EGFR (3 days), then validating the cells for expression levels (control set), before following it up with rescue using specific mutants (2 days). All this was prior to performing the actual experiment, which involved plating these rescued cells on the tension surface then fixing and immunostaining before imaging. Performing a successful experiment took 7 days, and I did it for more than five mutants with three technical replicates. In the end, the result was totally worth the effort.

When doing the research, did you have a particular result or ‘eureka’ moment that has stuck with you?

My ‘eureka’ moment, came pretty early while pursuing a different project. I was studying EGFR endocytosis on different tension surfaces using serum-starved Cos-7 cells. In order to stimulate endocytosis, I supplemented media with serum and while doing so it struck me that the growth factors within serum could potentially influence the observed changes in tension. On doing a quick literature survey, I realized that most of the previous research studying growth factor–integrin crosstalk had not explored the effects of individual growth factors on integrin tension. This triggered us to investigate the specific function of the growth factor EGF in a controlled and minimalistic system to pinpoint EGFR's role in regulating the observed tension outcomes.

Why did you choose Journal of Cell Science for your paper?

The decision to choose Journal of Cell Science for my paper was made based on the journal’s commitment to publish a diverse range of topics in cell biology purely based on scientific excellence. We strongly felt that our manuscript would be of significant interest to the cell biology community as it establishes a novel role for cooperative signaling between the two major receptor pathways (integrins and EGFR) that is central to cellular homeostasis and is dysregulated in cancer and developmental disorders of bone, heart, and the immune system. Additionally, the multifaceted and innovative scheme adopted in the manuscript combines mechanobiology tools with high-resolution microscopy to link signaling pathways and cellular mechanics. This novel approach should generate great interest among a broad range of cell biologists reading JCS to further explore its potential to understand different membrane protein crosstalks.

Have you had any significant mentors who have helped you beyond supervision in the lab? How was their guidance special?

My principal investigator Dr Alexa Mattheyses always believes in the scientific question I am trying to answer and is excited about having active discussions to decipher and understand the complexities experienced with every new question. She understands that difficult times are part and parcel of every project a scientist chooses to pursue, and she is ready to motivate, encourage and provide insights to foster my ideas. She provides me with the freedom to explore my ideas while ensuring I am grounded and focused on the scientific question at hand to make my science publishable and engaging to the scientific community.

Cellular fireworks. Bioart made from multiple Cos-7 cells plated on a tension gauge tether surface, highlighting integrin tension experienced by each cell. The image was acquired by total internal reflection fluorescence microscopy.

Cellular fireworks. Bioart made from multiple Cos-7 cells plated on a tension gauge tether surface, highlighting integrin tension experienced by each cell. The image was acquired by total internal reflection fluorescence microscopy.

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?

Like most children, I was quite clueless as a child about the career path I'd want to choose in life. I just followed what captured my interest and gave me immense happiness at every step of the way. It was always science in any form. And here I am. I have to credit my parents and my sisters for always encouraging the ‘mad’ scientist in me since childhood. They might still agree with that term as they continue to remain clueless about the specifics of my research. Being curious by nature, I have always liked to follow my own questions, so I suppose research was the best route to gratify my scientific urge.

Who are your role models in science? Why?

My all-time hall of famer role model is Dr C.V. Raman, whose seminal work in physics was influential in the growth of science in India. He was also the first Indian to have the honor of receiving a Nobel Prize for Physics, awarded in 1930 for the phenomenon of ‘Raman scattering’, commonly known as the ‘Raman effect’. On a more personal front, I was fortunate to be mentored by Dr Suresh Mahajan at the Institute of Science and Bhabha Atomic Research Center, very early on in my career. He truly changed my perception and approach towards science. He not only taught me to ask the right questions but also to think outside the box and to never be afraid of breaking the mold. He has made me more of a creative scientist and instilled in me a ‘never give up’ attitude.

What's next for you?

In the current paper, we established that ligand-activated EGFR mediates integrin mechanics, focal adhesion formation and maturation, and the spatial organization of focal adhesions. The next thing would be to elucidate the specific downstream signaling pathways involved in this process and identify post-translational modifications that influence EGFR's mechano-organizer role. Personally, I have always been passionate about microscopy and imaging and intend to transition from my current postdoctoral position to being a microscope facility director.

Tell us something interesting about yourself that wouldn't be on your CV

I am a self-trained plantsman and have a collection of more than 150 rare and exotic plants at my home, which helps me unwind at the end of each day. I also spend a considerable amount of time training my extremely cute dog, Lulu, who deserves a shout-out for being a constant source of joy.

Tejeshwar Rao's contact details: 941 THT, Department of Cell, Developmental, and Integrative Biology, 1900 University Boulevard, University of Alabama at Birmingham, Birmingham, AL 35294, USA.

E-mail: tjrao@uab.edu

Reference

Rao
,
T. C.
,
Ma
,
V. P.-Y.
,
Blanchard
,
A.
,
Urner
,
T. M.
,
Grandhi
,
S.
,
Salaita
,
K.
, and
Mattheyses
,
A. L
. (
2020
).
EGFR activation attenuates the mechanical threshold for integrin tension and focal adhesion formation
.
J. Cell Sci
.
133
,
jcs238840
.