The full-length gene encoding the histone deacetylase (HDAC)-like amidohydrolase (HDAH) from Bordetella or Alcaligenes (Bordetella/Alcaligenes) strain FB188 (DSM 11172) was cloned using degenerate primer PCR combined with inverse-PCR techniques and ultimately expressed in Escherichia coli. The expressed enzyme was biochemically characterized and found to be similar to the native enzyme for all properties examined. Nucleotide sequence analysis revealed an open reading frame of 1,110 bp which encodes a polypeptide with a theoretical molecular mass of 39 kDa. Interestingly, peptide sequencing disclosed that the N-terminal methionine is lacking in the mature wild-type enzyme, presumably due to the action of methionyl aminopeptidase. Sequence database searches suggest that the new amidohydrolase belongs to the HDAC superfamily, with the closest homologs being found in the subfamily assigned acetylpolyamine amidohydrolases (APAH). The APAH subfamily comprises enzymes or putative enzymes from such diverse microorganisms as Pseudomonas aeruginosa, Archaeoglobus fulgidus, and the actinomycete Mycoplana ramosa (formerly M. bullata). The FB188 HDAH, however, is only moderately active in catalyzing the deacetylation of acetylpolyamines. In fact, FB188 HDAH exhibits significant activity in standard HDAC assays and is inhibited by known HDAC inhibitors such as trichostatin A and suberoylanilide hydroxamic acid (SAHA). Several lines of evidence indicate that the FB188 HDAH is very similar to class 1 and 2 HDACs and contains a Zn 2؉ ion in the active site which contributes significantly to catalytic activity. Initial biotechnological applications demonstrated the extensive substrate spectrum and broad optimum pH range to be excellent criteria for using the new HDAH from Bordetella/ Alcaligenes strain FB188 as a biocatalyst in technical biotransformations, e.g., within the scope of human immunodeficiency virus reverse transcriptase inhibitor synthesis.Class 1 and 2 histone deacetylases (HDACs) (19), acetoin utilization proteins, and acetylpolyamine amidohydrolases (APAH) are members of the same superfamily (17) and may very well descend from a common ancestor (14). Sequence comparison reveals that all three classes of proteins share a number of common motifs. Additionally, they show significant functional similarities such as recognition of acetylated aminoalkyl groups and the removal of the acetyl moiety by cleaving an amide bond. Interestingly, the biological role of APAH is still a matter of speculation, although these enzymes are thought to be involved in degradative pathways of polyamines (20), particularly in the deacetylation of acetylpolyamines (23). However, experimental evidence to support this idea is still rather scarce. To date, only the APAH from Mycoplana ramosa has been described in detail. While some APAH were reported to cleave only acetylputrescine in vitro, M. ramosa APAH was described as less specific in the same experiments (23). Besides having a role in the degradative pathways of polyamines, APAH could, i...

A small subpopulation of tumor stem-like cells has the capacity to initiate tumors and mediate radio- and chemoresistance in diverse cancers hence also in glioblastoma (GBM). It has been reported that this capacity of tumor initiation in the brain is mainly dependent on the body’s nutrient supply. This population of so-called brain tumor initiating or brain tumor stem-like cells (BTSCs) is able to extract nutrients like glucose with a higher affinity. Riluzole, a drug approved for treating amyotrophic lateral sclerosis (ALS), was reported to possess anticancer properties, affecting the glutamate metabolism. We report that riluzole treatment inhibits the growth of brain tumor stem-like cells enriched cultures isolated from two human glioblastomas. The effects of riluzole on these cells were associated with an inhibition of a poor prognostic indicator: glucose transporter 3 (GLUT3). A decrease in GLUT3 is associated with a decrease in the p-Akt/HIF1α pathway. Further, downregulation of the DNA (Cytosine-5-)-methyltransferase 1 (DNMT1) gene that causes hypermethylation of various tumor-suppressor genes and leads to a poor prognosis in GBM, was detected. Two hallmarks of cancer cells—proliferation and cell death—were positively influenced by riluzole treatment. Finally, we observed that riluzole reduced the tumor growth in in vivo CAM assay, suggesting it could be a possible synergistic drug for the treatment of glioblastoma.

Background: KV10.1 is a potassium channel expressed in the brain and important for non-neural tumorigenesis.Results: An interaction between the C terminus of KV10.1 and the proline-rich domain of cortactin stabilizes the channel at the plasma membrane.Conclusion: Cortactin interacts with KV10.1 and controls surface expression of the channel.Significance: Our findings provide a functional and mechanistic link between the functions of two oncology-relevant proteins.

a b s t r a c t K V 10.1 is a potassium channel expressed in brain and implicated in tumor progression. We have searched for proteins interacting with K V 10.1 and identified Rabaptin-5, an effector of the Rab5 GTPase. Both proteins co-localize on large early endosomes induced by Rab5 hyperactivity. Silencing of Rabaptin-5 induces down-regulation of recycling of K V 10.1 channel in transfected cells and reduction of K V 10.1 current density in cells natively expressing K V 10.1, indicating a role of Rabaptin-5 in channel trafficking. K V 10.1 co-localizes, but does not physically interact, with Rab7 and Rab11. Our data highlights the complex control of the amount of K V 10.1 channels on the cell surface. Structured summary of protein interactions:Rabaptin-5 physically interacts with Kv10.1 by anti bait coimmunoprecipitation (View interaction) Rabaptin-5 physically interacts with Rabaptin-5 by two hybrid (View interaction) Kv10.1 physically interacts with Kv10.1 by two hybrid (View interaction) Kv10.1 physically interacts with Rabaptin-5 by anti bait coimmunoprecipitation (View Interaction: 1, 2) RAB11 and Kv10.1 colocalize by fluorescence microscopy (View interaction) Kv10.1 and Rabaptin-5 colocalize by fluorescence microscopy (View interaction) Kv10.1 physically interacts with Rabaptin-5 by two hybrid (View Interaction: 1, 2) Kv10.1 and RAB7 colocalize by fluorescence microscopy (View interaction)