Identification of a 220-kDa membrane tumor-associated antigen by human anti-UK114 monoclonal antibodies selected from the immunoglobulin repertoire of a cancer patient

A review of the mechanism of succinylation in cancer

Lysine succinylation is a novel, broad-spectrum, dynamic, non-enzymatic protein post-translational modification (PTM). Succinylation is essential for the regulation of protein function and control of various signaling and regulatory pathways. It is involved in several life activities, including glucose metabolism, amino acid metabolism, fatty acid metabolism, ketone body synthesis, and reactive oxygen species clearance, by regulating protease activity and gene expression. The level of succinylation is mainly regulated by succinyl donor, succinyltransferase, and desuccinylase. Many studies have confirmed that succinylation plays a role in tumorigenesis by creating tissue heterogeneity, and can promote or inhibit various cancers via the regulation of different substrate targets or signaling pathways. The mechanism of action of some antineoplastic drugs is related to succinylation. To better understand the role of succinylation modification in cancer development and treatment, the present study reviewed the current research content and latest progress of succinylation modification in cancer, which might provide a new direction and target for the prevention and treatment of cancer.

Evidence for a Negative Correlation between Human Reactive Enamine-Imine Intermediate Deaminase A (RIDA) Activity and Cell Proliferation Rate: Role of Lysine Succinylation of RIDA

Reactive intermediate deaminase (Rid) proteins are enzymes conserved in all domains of life. UK114, a mammalian member of RidA subfamily, has been firstly identified as a component of liver perchloric acid-soluble proteins (L-PSP). Although still poorly defined, several functions have been attributed to the mammalian protein UK114/RIDA, including the reactive intermediate deamination activity. The expression of UK114/RIDA has been observed in some tumors, arousing interest in this protein as an evaluable tumor marker. However, other studies reported a negative correlation between UK114/RIDA expression, tumor differentiation degree and cell proliferation. This work addressed the question of UK114/RIDA expression in human non-tumor HEK293 cell lines and in some human tumor cell lines. Here we reported that human RIDA (hRIDA) was expressed in all the analyzed cell line and subjected to lysine (K-)succinylation. In HEK293, hRIDA K-succinylation was negatively correlated to the cell proliferation rate and was under the control of SIRT5. Moreover, K-succinylation clearly altered hRIDA quantification by immunoblotting, explaining, at least in part, some discrepancies about RIDA expression reported in previous studies. We found that hRIDA was able to deaminate reactive enamine-imine intermediates and that K-succinylation drastically reduced deaminase activity. As predicted by in silico analysis, the observed reduction of deaminase activity has been related to the drastic alterations of hRIDA structure inferred by K-succinylation. The role of hRIDA and the importance of its K-succinylation in cell metabolism, especially in cancer biology, have been discussed.

Imine Deaminase Activity and Conformational Stability of UK114, the Mammalian Member of the Rid Protein Family Active in Amino Acid Metabolism

Reactive intermediate deaminase (Rid) protein family is a recently discovered group of enzymes that is conserved in all domains of life and is proposed to play a role in the detoxification of reactive enamines/imines. UK114, the mammalian member of RidA subfamily, was identified in the early 90s as a component of perchloric acid-soluble extracts from goat liver and exhibited immunomodulatory properties. Multiple activities were attributed to this protein, but its function is still unclear. This work addressed the question of whether UK114 is a Rid enzyme. Biochemical analyses demonstrated that UK114 hydrolyzes α-imino acids generated by l- or d-amino acid oxidases with a preference for those deriving from Ala > Leu = l-Met > l-Gln, whereas it was poorly active on l-Phe and l-His. Circular Dichroism (CD) analyses of UK114 conformational stability highlighted its remarkable resistance to thermal unfolding, even at high urea concentrations. The half-life of heat inactivation at 95 °C, measured from CD and activity data, was about 3.5 h. The unusual conformational stability of UK114 could be relevant in the frame of a future evaluation of its immunogenic properties. In conclusion, mammalian UK114 proteins are RidA enzymes that may play an important role in metabolism homeostasis also in these organisms.

Mmf1p Couples Amino Acid Metabolism to Mitochondrial DNA Maintenance in Saccharomyces cerevisiae

A variety of metabolic deficiencies and human diseases arise from the disruption of mitochondrial enzymes and/or loss of mitochondrial DNA. Mounting evidence shows that eukaryotes have conserved enzymes that prevent the accumulation of reactive metabolites that cause stress inside the mitochondrion. 2-Aminoacrylate is a reactive enamine generated by pyridoxal 5'-phosphate-dependent α,β-eliminases as an obligatory intermediate in the breakdown of serine. In prokaryotes, members of the broadly conserved RidA family (PF14588) prevent metabolic stress by deaminating 2-aminoacrylate to pyruvate. Here, we demonstrate that unmanaged 2-aminoacrylate accumulation in Saccharomyces cerevisiae mitochondria causes transient metabolic stress and the irreversible loss of mitochondrial DNA. The RidA family protein Mmf1p deaminates 2-aminoacrylate, preempting metabolic stress and loss of the mitochondrial genome. Disruption of the mitochondrial pyridoxal 5'-phosphate-dependent serine dehydratases (Ilv1p and Cha1p) prevents 2-aminoacrylate formation, avoiding stress in the absence of Mmf1p. Furthermore, chelation of iron in the growth medium improves maintenance of the mitochondrial genome in yeast challenged with 2-aminoacrylate, suggesting that 2-aminoacrylate-dependent loss of mitochondrial DNA is influenced by disruption of iron homeostasis. Taken together, the data indicate that Mmf1p indirectly contributes to mitochondrial DNA maintenance by preventing 2-aminoacrylate stress derived from mitochondrial amino acid metabolism.IMPORTANCE Deleterious reactive metabolites are produced as a consequence of many intracellular biochemical transformations. Importantly, reactive metabolites that appear short-lived in vitro have the potential to persist within intracellular environments, leading to pervasive cell damage and diminished fitness. To overcome metabolite damage, organisms utilize enzymatic reactive-metabolite defense systems to rid the cell of deleterious metabolites. In this report, we describe the importance of the RidA/YER057c/UK114 enamine/imine deaminase family in preventing 2-aminoacrylate stress in yeast. Saccharomyces cerevisiae lacking the enamine/imine deaminase Mmf1p was shown to experience pleiotropic growth defects and fails to maintain its mitochondrial genome. Our results provide the first line of evidence that uncontrolled 2-aminoacrylate stress derived from mitochondrial serine metabolism can negatively impact mitochondrial DNA maintenance in eukaryotes.

Der f 34, a Novel Major House Dust Mite Allergen Belonging to a Highly Conserved Rid/YjgF/YER057c/UK114 Family of Imine Deaminases

The high prevalence of house dust mite (HDM) allergy is a growing health problem worldwide, and the characterization of clinically important HDM allergens is a prerequisite for the development of diagnostic and therapeutic strategies. Here, we report a novel HDM allergen that belongs structurally to the highly conserved Rid/YjgF/YER057c/UK114 family (Rid family) with imine deaminase activity. Isolated HDM cDNA, named der f 34, encodes 128 amino acids homologous to Rid-like proteins. This new protein belongs to the Rid family and has seven conserved residues involved in enamine/imine deaminase activity. Indeed, we demonstrated that purified Der f 34 had imine deaminase activity that preferentially acted on leucine and methionine. Native Der f 34 showed a high IgE binding frequency as revealed by two-dimensional immunoblotting (62.5%) or ELISA (68%), which was comparable with those of a major HDM allergen Der f 2 (77.5 and 79%, respectively). We also found that Der f 34 showed cross-reactivity with another prominent indoor allergen source, Aspergillus fumigatus This is the first report showing that the Rid family imine deaminase represents an additional important pan-allergen that is conserved across organisms.

Human monoclonal antibody and vaccine approaches to prevent human rabies

Rabies, being a major zoonotic disease, significantly impacts global public health. It is invariably fatal once clinical signs are apparent. The majority of human rabies deaths occur in developing countries. India alone reports more than 50% of the global rabies deaths. Although it is a vaccine-preventable disease, effective rabies prevention in humans with category III bites requires the combined administration of rabies immunoglobulin (RIG) and vaccine. Cell culture rabies vaccines have become widely available in developing countries, virtually replacing the inferior and unsafe nerve tissue vaccines. Limitations inherent to the conventional RIG of either equine or human origin have prompted scientists to look for monoclonal antibody-based human RIG as an alternative. Fully human monoclonal antibodies have been found to be safer and equally efficacious than conventional RIG when tested in mice and hamsters. In this chapter, rabies epidemiology, reservoir control measures, post-exposure prophylaxis of human rabies, and combination therapy for rabies are discussed. Novel human monoclonal antibodies, their production, and the significance of plants as expression platforms are emphasized.

Reduced transaminase B (IlvE) activity caused by the lack of yjgF is dependent on the status of threonine deaminase (IlvA) in Salmonella enterica serovar Typhimurium

The YjgF/YER057c/UK114 family is a highly conserved class of proteins that is represented in the three domains of life. Thus far, a biochemical function demonstrated for these proteins in vivo or in vitro has yet to be defined. In several organisms, strains lacking a YjgF homolog have a defect in branched-chain amino acid biosynthesis. This study probes the connection between yjgF and isoleucine biosynthesis in Salmonella enterica. In strains lacking yjgF the specific activity of transaminase B, catalyzing the last step in the synthesis of isoleucine, was reduced. In the absence of yjgF, transaminase B activity could be restored by inhibiting threonine deaminase, the first enzymatic step in isoleucine biosynthesis. Strains lacking yjgF showed an increased sensitivity to sulfometruron methyl, a potent inhibitor of acetolactate synthase. Based on work described here and structural reports in the literature, we suggest a working model in which YjgF has a role in protecting the cell from toxic effects of imbalanced ketoacid pools.

Recombinant perchloric acid-soluble protein suppresses the immunoglobulin production of human-human hybridoma HB4C5 cells

Because perchloric acid-soluble protein (PSP) has been conserved evolutionally in various species from Escherichia coli to humans, it may reflect an involvement in basic cellular regulation. However, the precise function of PSP is currently unknown. In this study, we examined the direct effect of PSP on the production of immunoglobulin (Ig) using human B, HB4C5, NAT-30, and U266 cells because it has been reported that subcutaneous administration of PSP affects rodent immune systems. Suppression of Ig productivity and decrement of the cell viability was recognized only in HB4C5 cells by the addition of PSP into the medium. On the other hand, PSP had no effect on Ig productivity and cell viability in NAT-30 and U266 cells. In addition, PSP was clearly incorporated by HB4C5 but not by the other cells. These results suggest that the Ig production suppressed by PSP, which has been previously reported to inhibit protein synthesis, contributed to the incorporation of PSP into the HB4C5 cells.