Professor Dipali Sashital

Dr. Dipali G. Sashital is an Associate Professor in the Department of Biochemistry, Biophysics and Molecular Biology at Iowa State University in Ames, IA. Professor Sashital is an expert in RNA structure and function, having trained with three eminent RNA biochemists. She obtained her Ph.D. in Biochemistry at the University of Wisconsin (Madison) in the laboratory of Professor Samuel E. Butcher. Following her doctoral studies, Dr. Sashital moved out West, where she completed her postdoctoral training in the laboratories of Professor Jennifer A. Doudna at University of California, Berkeley and Professor James R. Williamson at The Scripps Research Institute in La Jolla.

Currently, Professor Sashital’s laboratory is working to “ensure that our fundamental understanding of the native roles of CRISPR-Cas systems as defense mechanisms informs our adoption of Cas effectors as safe and effective biotechnological tools.” She is particularly interested in trying to understand the origin and potential biological consequences of off-target cuts made by CRISPR-Cas systems, stating that “Cas effectors like Cas9 and Cas12a are powerful because they can be programmed to cleave a sequence that is complementary to the guide RNA. However, it is possible that Cas effectors can also cleave sites with limited complementarity to the guide, potentially causing unwanted edits during genome editing experiments. This variability is surprising given the role of these proteins as immune effectors. My lab is beginning to understand this variability and its effect(s) on long-term immunity in bacteria, as phages might readily evolve and escape from highly specific immune effectors.”  

Professor Sashital’s interest in CRISPR-Cas systems first arose during her time as a post-doctoral fellow in Professor Jennifer A. Doudna’s (2020 Nobel Laureate) lab. “When I joined the Doudna lab in 2008, I initially pursued a project on the biogenesis pathways of recently discovered piwi-interacting RNAs. It was an exciting time in the Dounda lab, because the lab had just begun to transition from studying eukaryotic small RNA pathways to also investigating prokaryotic CRISPR-Cas systems. At the time, very little was known about these RNA-guided defense mechanisms, so group meetings presented by my amazing labmates Blake (Dr. Wiedenheft), Rachel (Dr. Haurwitz) and Martin (Dr. Jinek) were particularly exciting. Their projects took off rapidly, and Jennifer asked me to join the CRISPR team as a side project to my piRNA studies. But CRISPR quickly became my main focus.”

“You should always listen to the advice that you are given, but you do not necessarily need to follow it. […] It is not always *possible* to follow all advice, because you will often receive conflicting suggestions from different people. The best way to decide whether to follow advice is to be mindful of what is the best fit for you. There is not a one-size-fits-all path in science, or in life in general!”

From that moment, Dr. Sashital began making important contributions to our understanding of how CRISPR-Cas systems function. Significantly, she was the first to discover how Cas effectors like Cas9 can rapidly search genomes and identify a target for cleavage. She still vividly remembers this discovery: “In 2011, I did a set of experiments that strongly suggested that Cas effectors require a short sequence called PAM (protospacer adjacent motif) to unwind DNA and allow for base pairing with the guide RNA. While there was not a real Eureka moment, the slow accumulation of data pointing toward this model was one of the most exciting periods of my career. My continued fascination with this model has shaped many of the mechanistic studies from my lab, which have focused on how PAM engagement impacts Cas effectors function.”

When asked to reflect on the challenges she had to face during her career, Professor Sashital recalled moments when she transitioned from one stage of her career to the next. In particular, she mentions how overwhelming her transition from a senior postdoc to a PI felt. “For the first time in my career, I had critical responsibilities to other people. Realizing the enormity of this task, I remember being very nervous about mentoring graduate students in my lab. But I did not anticipate that students outside of my lab would also look to me for leadership and guidance. Advocating for trainees has required that I work on being a more assertive person who speaks up on behalf of students at faculty meetings and conferences.”

Dr. Sashital encourages trainees not to be afraid to engage with their scientific communities. She shared that, “I think it is essential that trainees feel comfortable asking questions. This may be obvious, as being inquisitive is a central part of being a scientist. But new scientists often tend to hold back questions. This may be due to nervousness about appearing unfamiliar with a subject, or a hesitation while mulling over the precise wording of the question. These factors certainly hampered my ability to ask questions when I was a trainee, and I have also observed this in trainees who I have worked with during my career.”

At the same time, Dr. Sashital also points out how advice can be a double-edged sword. “You should always listen to the advice that you are given, but you do not necessarily need to follow it. As I have advanced in my career, I have found that it is not always *possible* to follow all advice, because you will often receive conflicting suggestions from different people. The best way to decide whether to follow advice is to be mindful of what is the best fit for you. There is not a one-size-fits-all path in science, or in life in general!”

Dr. Sashital was awarded as RNA Society Scaringe Young Scientist Award in 2012. Professor Sashital highly recommends getting involved in the RNA Society as a student, “I feel very fortunate to have been part of the RNA Society since my first year as a graduate student. The organized meetings provide amazing opportunities for trainees. I gave my first “real” talk at the 2004 RNA Society Meeting, during a plenary session in front of > 800 people. That was a formative moment in my career, and one that built my confidence immensely. Attending the meeting every year also allowed me to form friendships with students from all over the country and the world. I have continued to interact with people that I met at RNA throughout my career, even as we have all moved on to new stages of our careers.”

When not in the lab, you are likely to find Dr. Sashital cooking or watching a Michigan football or Red Wings game. “I grew up in a suburb of Detroit, about half-way between Detroit and Ann Arbor. As a result, I am a huge fan of Detroit-area sports teams and Michigan athletics (I am also an alum!).”

Dr. Sashital’s favorite RNA is the U2-U6 snRNA complex that forms the catalytic core of the spliceosome. “I am still very partial to the U2-U6 complex (technically two RNAs rather than one!). When I began working on my PhD work, we had little hope that we would ever have atomic resolution structures of the spliceosome. […] Getting to see the various conformations and complexes formed by U2 and U6 snRNAs over the splicing cycle in recent cryo-EM structures has been an incredible treat!” You can learn more about Dr. Sashital’s work by visiting her website http://www.sashitallab.org/, or following her on Twitter @dsashital.