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SUMMARY:Understanding the Mechanisms of Biological Events by Using Mathema
 tical Modeling
DTSTART:20161014T110000
DTEND:20161014T120000
DTSTAMP:20260921T140819Z
UID:aa720c5183f7c07a98f1e6fcbd7a6ba0da90760413ed0248a02560c9
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Ryoichiro Kageyama\nAlthough biological events proceed acc
 ording to mathematical rules\, it is not easy to bring these two disciplin
 es\, biology and mathematics\, together in actual research. In my lecture\
 , I would like to present some examples showing how mathematics is importa
 nt to understand the basic mechanism of biological events. Our group has b
 een analyzing the mechanism of the somite segmentation clock\, which regul
 ates the periodic formation of somites. Somites are metameric structures\,
  which later give rise to the vertebral column\, ribs\, skeletal muscles a
 nd subcutaneous tissues. In mouse embryos\, a total of ~65 pairs of somite
 s are formed sequentially from the rostral to caudal orientation\, and eac
 h pair is formed every two hours under the control of the segmentation clo
 ck. We found that the transcriptional repressor Hes7 is expressed in an os
 cillatory manner with a period of two hours during this process. Both the 
 loss of expression and sustained expression of Hes7 lead to fusion of somi
 tes and somite-derived tissues\, indicating that oscillatory expression of
  Hes7 is required for somite segmentation. Hes7 oscillation is regulated b
 y negative feedback with delayed timing\, and this dynamic expression has 
 been mathematically simulated by differential-delay equations. We found th
 at reducing the number of introns within the Hes7 gene shortens the delay 
 and results in abolishment or a more rapid tempo of Hes7 oscillation and s
 omite segmentation\, as predicted by mathematical modeling. We also found 
 that Hes1\, a Hes7-related transcriptional repressor\, is expressed in an 
 oscillatory manner by many cell types\, including neural stem cells. In th
 ese cells\, Hes1 oscillation drives cyclic expression of other factors\, a
 nd oscillatory expression of these factors is very important for prolifera
 tion of neural stem cells. Interestingly\, gene expression oscillates in p
 hase between neighboring cells during somite segmentation but out of phase
  between neighboring neural stem cells. These different oscillatory dynami
 cs can be explained by a unified mathematical model.
LOCATION:SV 1717 https://plan.epfl.ch/?room==SV%201717
STATUS:CONFIRMED
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