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Talk abstract:
Sensing and Refilling Calcium Stores in an Excitable Gland Cell:
Can math models make nontrivial predictions about biology?
Yue-Xian Li, Univ. of British Columbia
Mathematical models of important biological phenomena have
provided insights about whether and how a verbally stated model can work
in an accurate and quantitative sense. Biology has also given
mathematicians a variety of challenging math problems that later live a
more mathematical life with little biological consequences. However, it
was the close combination of the two, in pursuing the unknown facts that
would be difficult to achieve without the combination, which made the work of
people like Hodgkin-Huxley a big success story. This talk will focus on
the efforts of myself and coworkers to use math models, based on a large
number of records, to make predictions on issues relevant to the real
biological problem. The first part will be on how, by focusing on the
whole dose-response scenario instead of a single record in pituitary
gonadotrophs, the model predicts that the bell-shaped curve moves to
the right as IP3 concentration increases. This prediction has been
recently proved by experiments. The second part will be on what the model
says about the communication between the cell surface and the endoplasmic
reticulum (ER) calcium store in controlling Ca2+
entry and store refilling in gonadotrophs that
are excitable and relatively small. Our study predicted some seemingly
counterintuitive phenomena such as that store refilling occurs at lower than
basal [Ca2+]i levels and, most importantly, suggested that in
excitable cells that do not express Icrac [Ca2+]i
itself plays the role of
a messenger between the ER and the plasma membrane. These results
indicate that capacitative Ca2+ entry in
such cells is likely to occur
through Ca2+-controlled Ca2+ entry.
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