Characterizing small ubiquitin like modification of ING1

The INhibitor of Growth (ING) proteins have been classified as type II tumor suppressors, being frequently reported to mis-localize or be repressed in several forms of cancer. The ING family consists of 5 genes (ing1-5) encoding multiple protein isoforms. The most conserved domain found in the INGs is the Plant Homeo Domain (PHD) that is commonly found in chromatin remodeling proteins. ING1 and ING2 are a part of the Sin3A-HDAC1/2 protein complex and ING3, ING4, ING5 associate with different HAT complexes. Based upon comprehensive interactome analyses, the 3 yeast ING proteins are predicted to specifically associate with >1,000 yeast proteins. Many recent reports suggest roles for ING proteins in DNA damage repair, apoptosis, chromatin remodeling, angiogenesis, metastasis and senescence, however how the proteins themselves are regulated by various post translational modifications is not yet clear. We have identified a novel post-translational modification of ING1 and altogether our data suggests the role of this modification in ING1 mediated gene regulation.2 year

SPATA2 links CYLD to the TNF-α receptor signaling complex and modulates the receptor signaling outcomes

TNF‐α is a key regulator of innate immune and proinflammatory responses. However, the composition of the TNF‐α receptor‐associated signaling complexes (TNF‐RSC) and the architecture of the downstream signaling networks are incompletely understood. We employed quantitative mass spectrometry to demonstrate that TNF‐α stimulation induces widespread protein phosphorylation and that the scope of phosphorylation expands in a temporal manner. TNF‐α stimulation also induces rapid ubiquitylation of components of the TNF‐RSC. Temporal analysis of the TNF‐RSC composition identified SPATA2 as a novel component of the TNF‐RSC. The predicted PUB domain in the N‐terminus of SPATA2 interacts with the USP domain of CYLD, whereas the C‐terminus of SPATA2 interacts with HOIP. SPATA2 is required for recruitment of CYLD to the TNF‐RSC. Downregulation of SPATA2 augments transcriptional activation of NF‐κB and inhibits TNF‐α‐induced necroptosis, pointing to an important function of SPATA2 in modulating the outcomes of TNF‐α signaling. Taken together, our study draws a detailed map of TNF‐α signaling, identifies SPATA2 as a novel component of TNF‐α signaling, and provides a rich resource for further functional investigations

SUMOylation of the ING1b tumour suppressor regulates gene transcription.

International audienceThe INhibitor of Growth (ING) proteins are encoded as multiple isoforms in five ING genes (ING1-5) and act as type II tumor suppressors. They are growth inhibitory when overexpressed and are frequently mislocalized or down-regulated in several forms of cancer. ING1 and ING2 are stoichiometric members of histone deacetylase (HDAC) complexes while ING3-5 are stoichiometric components of different histone acetyl-transferase (HAT) complexes. The INGs target these complexes to histone marks, thus acting as epigenetic regulators. ING proteins affect angiogenesis, apoptosis, DNA repair, metastasis and senescence, but how the proteins themselves are regulated is not yet clear. Here we find a small ubiquitin like modification (SUMOylation) of the ING1b protein and identify lysine 193 (K193) as the preferred ING1b SUMO acceptor site. We also show that PIAS4 is the E3 SUMO ligase responsible for ING1b SUMOylation on K193. Sequence alignment reveals that the SUMO consensus site on ING1b contains a phosphorylation-dependent SUMOylation motif (PDSM) and our data indicate that the SUMOylation on K193 is enhanced by the S199D phosphomimic mutant. Using an ING1b protein mutated at the major SUMOylation site (ING1b E195A), we further demonstrate that ING1b SUMOylation regulates the binding of ING1b to the ISG15 and DGCR8 promoters, consequently regulating ISG15 and DGCR8 transcription. These results suggest a role for ING1b SUMOylation in the regulation of gene transcription

STK3 is a therapeutic target for a subset of acute myeloid leukemias

Acute myeloid leukemia (AML) is characterized by uncontrolled proliferation and accumulation of immature myeloblasts, which impair normal hematopoiesis. While this definition categorizes the disease into a distinctive group, the large number of different genetic and epigenetic alterations actually suggests that AML is not a single disease, but a plethora of malignancies. Still, most AML patients are not treated with targeted medication but rather by uniform approaches such as chemotherapy. The identification of novel treatment options likely requires the identification of cancer cell vulnerabilities that take into account the different genetic and epigenetic make-up of the individual tumors. Here we show that STK3 depletion by knock-down, knock-out or chemical inhibition results in apoptotic cells death in some but not all AML cell lines and primary cells tested. This effect is mediated by a premature activation of cyclin dependent kinase 1 (CDK1) in presence of elevated cyclin B1 levels. The anti-leukemic effects seen in both bulk and progenitor AML cells suggests that STK3 might be a promising target in a subset of AML patients