The menin tumor suppressor protein is phosphorylated in response to DNA damage.
BACKGROUND
Multiple endocrine neoplasia type 1 (MEN1) is a heritable cancer syndrome characterized by tumors of the pituitary, pancreas and parathyroid. Menin, the product of the MEN1 gene, is a tumor suppressor protein that functions in part through the regulation of transcription mediated by interactions with chromatin modifying enzymes.


RESULTS
Here we show menin association with the 5' regions of DNA damage response genes increases after DNA damage and is correlated with RNA polymerase II association but not with changes in histone methylation. Furthermore, we were able to detect significant levels of menin at the 3' regions of CDKN1A and GADD45A under conditions of enhanced transcription following DNA damage. We also demonstrate that menin is specifically phosphorylated at Ser394 in response to several forms of DNA damage, Ser487 is dynamically phosphorylated and Ser543 is constitutively phosphorylated. Phosphorylation at these sites however does not influence the ability to interact with histone methyltransferase activity. In contrast, the interaction between menin and RNA polymerase II is influenced by phosphorylation, whereby a phospho-deficient mutant had a higher affinity for the elongating form of RNA polymerase compared to wild type. Additionally, a subset of MEN1-associated missense point mutants, fail to undergo DNA damage dependent phosphorylation.


CONCLUSIONS
Together, our findings suggest that the menin tumor suppressor protein undergoes DNA damage induced phosphorylation and participates in the DNA damage transcriptional response.
Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, United States of America.
Joshua
J
Francis
Wenchu
W
Lin
Orit
O
Rozenblatt-Rosen
Matthew
M
Meyerson
D002460:Cell Line; D004249:DNA Damage / Q000235:genetics*; D006801:Humans; D010766:Phosphorylation / Q000502:physiology; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D014158:Transcription, Genetic; D025521:Tumor Suppressor Proteins / Q000378:metabolism*
C105373:MEN1 protein, human; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; D012694:Serine; D012319:RNA Polymerase II
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