研究发现糖在细胞的生命周期充当重要角色

The  discovery  reveals  that,  when  disturbed,  this  process  could  contribute  to  cancer  or  other  diseases  by  failing  to  properly  control  the  steps  and  timing  of  cell  division,  the  researchers  say.  The  findings  are  described  in  the  Sept.  23  issue  of  the  Journal  of  Biological  Chemistry,  available  online  now.

The  sugar,  known  as  O-GlcNAc  (pronounced  oh-GLUCK-nack),  is  used  inside  cells  to  modify  proteins,  turning  the  proteins  off  or  on,  helping  or  preventing  their  interactions  with  other  proteins,  keeping  them  from  destruction  or  allowing  their  destruction.  The  comings  and  goings  of  the  sugar  on  proteins  seem  to  be  important  controllers  of  cell  division,  say  the  researchers.

"The  dogma  for  decades  has  been  that  the  cycle  of  cell  division  is  controlled  by  the  appearance  and  disappearance  of  certain  proteins  called  cyclins,  but  experiments  have  shown  that  you  can  knock  out  any  of  these  and  still  get  perfectly  normal  cell  division,"  says  the  study's  first  author,  Chad  Slawson,  Ph.D.,  a  postdoctoral  fellow  in  biological  chemistry  in  Johns  Hopkins'  Institute  for  Basic  Biomedical  Sciences.  "In  contrast,  our  experiments  show  that  by  increasing  or  decreasing  the  amount  of  sugar  attached  to  proteins,  the  cell  cycle  is  disrupted  and  isn't  salvageable  unless  O-GlcNAc  levels  are  fixed."

In  experiments  with  human  cells  and  mouse  cells,  Slawson  and  his  colleagues  showed  that  preventing  a  cell  from  removing  the  sugar  from  proteins  causes  the  cell  to  copy  its  genetic  material  and  make  new  nuclei,  but  to  fail  to  divide  in  two.  The  end  result  is  cells  with  more  than  one  nucleus  --  a  situation  fairly  common  in  cancer  cells.

"Cells  with  more  than  one  nucleus  can  survive,  but  they  are  dysregulated  --  things  just  don't  go  right,"  says  Slawson.  "The  longer  they  survive,  the  worse  it  gets."   (责任编辑：泉水)

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研究发现糖在细胞的生命周期充当重要角色