May 2022
Abstract:
Over 90% of our genes are
interrupted by regions, called introns, that must be removed from the
corresponding transcripts prior to their translation into protein. The
process by which introns are removed from pre-mRNA is referred to as
splicing, and it is carried out by a multi-megadalton complex of
proteins and small, nuclear RNAs. Humans have more than 200,000 introns,
suggesting either an aggressive neutral mechanism for their
proliferation or else selection for some beneficial function. Given the
complexity of human splicing, it has been challenging to gain a
comprehensive understanding of the roles that introns play. My lab has
therefore turned to the thermoacidophilic red alga C. merolae,
whose intron complement has shrunk from nearly 2000 ancestrally to only
38 today. We have shown that the splicing machinery has correspondingly
been dramatically reduced. To investigate why 38 introns might be
retained, we have been systematically deleting C. merolae's
introns, as well as studying its splicing responses under a variety of
conditions. We find that some introns accumulate in response to heat
stress, suggesting that the introns themselves play a role in adapting
to heat. Our results add to a growing body of work suggesting that
introns are not merely junk that needs to be removed, but in fact have
inherent roles that support cellular responses to environmental change.
Bio:
Dr. Stephen Rader is a Professor of Biochemistry at the University of
Northern British Columbia in Prince George. He earned his Ph.D. in X-ray
crystallography and protein dynamics under the supervision of David
Agard at UC San Francisco. For his postdoctoral work, he joined the lab
of Christine Guthrie, also at UCSF, where he entered the exciting world
of RNA science and learned the tools of yeast genetics and biochemistry.
After starting his own lab at UNBC in 2003, he sought a thermophilic
system with which to investigate pre-mRNA splicing, and eventually began
working with C. merolae, whose genome had recently been sequenced. Despite the challenges of developing a completely new splicing system, C. merolae
continues to yield surprises and insights into the evolution of introns
and splicing. When he is not studying RNA, Professor Rader enjoys
backpacking and back-country skiing.