title: Tankyrase 1 interacts with Mcl-1 proteins and inhibits their regulation of apoptosis.
abstract: Mcl-1L (myeloid cell leukemia-1 long) is an antiapoptotic Bcl-2 family protein discovered as an early induction gene during leukemia cell differentiation. Previously, we identified Mcl-1S (short) as a short splicing variant of the Mcl-1 gene with proapoptotic activity. To identify Mcl-1-interacting proteins, we performed yeast two-hybrid screening and found cDNAs encoding tankyrase 1. This protein possesses poly(ADP-ribose) polymerase activity and presumably facilitates the turnover of substrates following ADP-ribosylation. In yeast and mammalian cells, tankyrase 1 interacts with both Mcl-1L and Mcl-1S, but does not bind to other Bcl-2 family proteins tested. Analysis of truncated tankyrase 1 mutants indicated that the first 10 ankyrin repeats are involved in interaction with Mcl-1. In the N terminus of Mcl-1, a stretch of 25 amino acids is sufficient for binding to tankyrase 1. Overexpression of tankyrase 1 antagonizes both Mcl-1L-mediated cell survival and Mcl-1S-induced cell death. Furthermore, coexpression of tankyrase 1 with Mcl-1L or Mcl-1S decreased the levels of Mcl-1 proteins. Although tankyrase 1 down-regulates Mcl-1 protein expression, no ADP-ribosylation of Mcl-1 was detected. In contrast, overexpression of Mcl-1 proteins suppressed the ADP-ribosylation of the telomeric repeat binding factor 1, another tankyrase 1-interacting protein. Thus, interaction of Mcl-1L and Mcl-1S with tankyrase 1 could serve as a unique mechanism to decrease the expression of these Bcl-2 family proteins, thereby leading to the modulation of the apoptosis pathway.
authors.affiliation: Division of Reproductive Biology, Department of Gynecology and Obstetrics, Stanford University School of Medicine, Stanford, California 94305-5317, USA.
authors.forename: Jeehyeon
authors.initials: J
authors.lastname: Bae
authors.forename: Jill R
authors.initials: JR
authors.lastname: Donigian
authors.forename: Aaron J W
authors.initials: AJ
authors.lastname: Hsueh
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D016466:CHO Cells; D006224:Cricetinae; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D006801:Humans; D020014:K562 Cells; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D038501:Tankyrases / Q000235:genetics / Q000378:metabolism*
chemical_list: D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D038501:Tankyrases; C418109:TNKS protein, human