Apr 2022
Host: Professor Kyle Lauersen
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.