Regulation of HuR function by ATM/ATR Chk1/Chk2. ATM/ATR regulates HuR function through the activation of Chk1 and Chk2. Active Chk1 phosphorylates (and hence inactivates) Cdk1, a kinase that phosphorylates HuR at S202; in turn, unphosphorylated HuR(S202) can be transported to the cytoplasm (orange). Active Chk2 phosphorylates HuR at S88, S100, and T118 (at RRM1 and RRM2); in turn, HuR association with target mRNAs is altered (purple). Jointly, ATM/ATR Chk1/Chk2 modulates the amount of HuR in the cytoplasm and its interaction with target mRNAs (green).
