Molecular characterization of the E2 conjugating enzyme LinfUbc13 in Leishmania infantum.

UBC13 is an orthologue of Homo sapiens ubiquitin-conjugation E2 enzymes described in Leishmania mexicana, a null mutant lacking this gene cannot be produced, suggesting essential functions in this parasite. Leishmania infantum is an etiological agent of visceral leishmaniasis, the most severe type of disease that is potentially fatal if untreated. The ubiquitination process has been targeted for leishmanicidal compounds, indicating its essential function in parasite homeostasis.

The recombinant L-lysine α-oxidase from the fungus Trichoderma harzianum promotes apoptosis and necrosis of leukemia CD34 + hematopoietic cells.

Background: In hematologic cancers, including leukemia, cells depend on amino acids for rapid growth. Anti-metabolites that prevent their synthesis or promote their degradation are considered potential cancer treatment agents. Amino acid deprivation triggers proliferation inhibition, autophagy, and programmed cell death.

Liquid Modernity and Imagistic Production: Reflections on Social Media and Free Associations.

Social media has profound impact on how we experience the world and interact with others. Rapidly advancing technology has created platforms that have become increasingly image-based and emotionally manipulative. Do the new patterns of communication change patients' mental processes? Is free association becoming more imagistic? Contemporary clinical settings invite new perspectives on the intersections between the social and individual realms, patients' modes of expression, and analysts' interpretations.

Modulation of the Host Nuclear Compartment by Uncovers Effects on Host Transcription and Splicing Machinery.

Host manipulation is a common strategy for invading pathogens. , the causative agent of Chagas Disease, lives intracellularly within host cells. During infection, parasite-associated modifications occur to the host cell metabolism and morphology.

The E3 ubiquitin ligase SCF(Fbxo7) mediates proteasomal degradation of UXT isoform 2 (UXT-V2) to inhibit the NF-κB signaling pathway.

Background: Ubiquitously eXpressed Transcript isoform 2 (UXTV2) is a prefoldin-like protein involved in NF-κB signaling, apoptosis, and the androgen and estrogen response. UXT-V2 is a cofactor in the NF-κB transcriptional enhanceosome, and its knockdown inhibits TNF-α -induced NF-κB activation. Fbxo7 is an F-box protein that interacts with SKP1, Cullin1 and RBX1 proteins to form an SCF(Fbxo7) E3 ubiquitin ligase complex.

Tumor necrosis factor receptor-associated factor 6 interaction with alpha-synuclein enhances cell death through the Nuclear Factor-kB pathway.

Background: Parkinson's disease (PD) is a neurodegenerative disease characterized by intracellular inclusions named Lewy bodies (LB), and alpha-synuclein (asyn) is the major component of these protein aggregates. The precise physiological and pathological roles of asyn are not fully understood. Nevertheless, asyn present in LB is ubiquitinated but fails to reach the 26S proteasome.

Identification of potential target genes associated with the reversion of androgen-dependent skeletal muscle atrophy.

Muscle wasting or atrophy is extensively associated with human systemic diseases including diabetes, cancer, and kidney failure. Accumulating evidence from transcriptional profiles has noted that a common set of genes, termed atrogenes, is modulated in atrophying muscles. However, the transcriptional changes that trigger the reversion or attenuation of muscle atrophy have not been characterized at the molecular level until now.

DNA damage response signaling does not trigger redistribution of SAMHD1 to nuclear foci.

SAMHD1 (Sterile alpha motif and histidine-aspartic acid (HD) domain containing protein 1) is a deoxyribonucleoside triphosphate (dNTP) triphosphohydrolase (dNTPase) that restricts viral replication in infected cells. This protein is also involved in DNA repair by assisting in DNA end resection by homologous recombination (HR) after DNA double-strand break (DSB) induction with camptothecin (CPT) or etoposide (ETO). We showed that a monoclonal anti-SAMHD1 antibody produced against the full-length protein detected an unspecific 50 kDa protein that colocalized with dot-like structures after CPT treatment in HeLa cells.

Expression, purification, and characterization of the TRIM49 protein.

Autophagy is the process of degradation of intracellular proteins through the lysosome. Members of the tripartite motif (TRIM) proteins have shown to directly recognize autophagic cargo and also to act as a hub for the phagophore nucleation complex. The TRIM proteins are classically characterized by the presence of an amino-terminal RING domain and a B-box domain followed by a coiled coil domain.

FBXO25 regulates MAPK signaling pathway through inhibition of ERK1/2 phosphorylation.

The FBXO25 mediates degradation of ELK-1 and thus inhibits transcriptional activation of immediate early genes (iEG). Here we show that FBXO25 regulates yet another node of this signaling pathway, by decreasing MAPK/ERK activity. We show that induction of FBXO25 reduced ERK1/2 phosphorylation independently of MEK1/2.

The kinin B1 receptor regulates muscle-specific E3 ligases expression and is involved in skeletal muscle mass control.

Regulation of muscle mass depends on the balance between synthesis and degradation of proteins, which is under the control of different signalling pathways regulated by hormonal, neural and nutritional stimuli. Such stimuli are altered in several pathologies, including COPD (chronic obstructive pulmonary disease), diabetes, AIDS and cancer (cachexia), as well as in some conditions such as immobilization and aging (sarcopenia), leading to muscle atrophy, which represents a significant contribution to patient morbidity. The KKS (kallikrein-kinin system) is composed of the enzymes kallikreins, which generate active peptides called kinins that activate two G-protein-coupled receptors, namely B1 and B2, which are expressed in a variety of tissues.

Angiotensin II-independent angiotensin-(1-7) formation in rat hippocampus: involvement of thimet oligopeptidase.

The involvement and relevance of the renin-angiotensin system have been established clearly in cardiovascular diseases, and renin-angiotensin system involvement has also been investigated extensively in the central nervous system. Angiotensin II acts classically by binding to the AT1 and AT2 receptors. However, other pathways within the renin-angiotensin system have been described more recently, such as one in which angiotensin-(1-7) (Ang-(1-7)) binds to the receptor Mas.

The F-box protein FBXO25 promotes the proteasome-dependent degradation of ELK-1 protein.

FBXO25 is one of the 69 known human F-box proteins that serve as specificity factors for a family of ubiquitin ligases composed of SKP1, Rbx1, Cullin1, and F-box protein (SCF1) that are involved in targeting proteins for degradation across the ubiquitin proteasome system. However, the substrates of most SCF E3 ligases remain unknown. Here, we applied an in chip ubiquitination screen using a human protein microarray to uncover putative substrates for the FBXO25 protein.

Molecular characterization of the Aspergillus nidulans fbxA encoding an F-box protein involved in xylanase induction.

The filamentous fungus Aspergillus nidulans has been used as a fungal model system to study the regulation of xylanase production. These genes are activated at transcriptional level by the master regulator the transcriptional factor XlnR and repressed by carbon catabolite repression (CCR) mediated by the wide-domain repressor CreA. Here, we screened a collection of 42 A.

Time course of skeletal muscle loss and oxidative stress in rats with Walker 256 solid tumor.

Reactive oxygen species oxidize proteins and modulate the proteasomal system in muscle-wasting cancer cachexia. On day 5 (D5), day 10 (D10), and day 14 (D14) after tumor implantation, skeletal muscle was evaluated. Carbonylated proteins and thiobarbituric acid reactive substances were measured.

Identification of FBXO25-interacting proteins using an integrated proteomics approach.

FBXO25 is one of the 68 human F-box proteins that serve as specificity factors for a family of ubiquitin ligases composed of s-phase-kinase associated protein 1, really interesting new gene-box 1, Cullin 1, and F-box protein (SCF1) that are involved in targeting proteins for destruction across the ubiquitin proteasome system. We recently reported that the FBXO25 protein accumulates in novel subnuclear structures named FBXO25-associated nuclear domains (FAND). Combining two-step affinity purification followed by MS with a classical two-hybrid screen, we identified 132 novel potential FBXO25 interacting partners.

Testosterone represses ubiquitin ligases atrogin-1 and Murf-1 expression in an androgen-sensitive rat skeletal muscle in vivo.

Skeletal muscle atrophy induced by denervation and metabolic diseases has been associated with increased ubiquitin ligase expression. In the present study, we evaluate the influence of androgens on muscle ubiquitin ligases atrogin-1/MAFbx/FBXO32 and Murf-1/Trim63 expression and its correlation with maintenance of muscle mass by using the testosterone-dependent fast-twitch levator ani muscle (LA) from normal or castrated adult male Wistar rats. Gene expression was determined by qRT-PCR and/or immunoblotting.

Atrogin-1 and MuRF1 regulate cardiac MyBP-C levels via different mechanisms.

Aims: Familial hypertrophic cardiomyopathy (FHC) is frequently caused by cardiac myosin-binding protein C (cMyBP-C) gene mutations, which should result in C-terminal truncated mutants. However, truncated mutants were not detected in myocardial tissue of FHC patients and were rapidly degraded by the ubiquitin-proteasome system (UPS) after gene transfer in cardiac myocytes. Since the diversity and specificity of UPS regulation lie in E3 ubiquitin ligases, we investigated whether the muscle-specific E3 ligases atrogin-1 or muscle ring finger protein-1 (MuRF1) mediate degradation of truncated cMyBP-C.

Arginine methylation analysis of the splicing-associated SR protein SFRS9/SRP30C.

The human SFRS9/SRp30c belongs to the SR family of splicing regulators. Despite evidence that members of this protein family may be targeted by arginine methylation, this has yet to be experimentally addressed. In this study, we found that SFRS9 is a target for PRMT1-mediated arginine methylation in vitro, and that it is immunoprecipitated from HEK-293 lysates by antibodies that recognize both mono- and dimethylated arginines.

Functional association of human Ki-1/57 with pre-mRNA splicing events.

The cytoplasmic and nuclear protein Ki-1/57 was first identified in malignant cells from Hodgkin's lymphoma. Despite studies showing its phosphorylation, arginine methylation, and interaction with several regulatory proteins, the functional role of Ki-1/57 in human cells remains to be determined. Here, we investigated the relationship of Ki-1/57 with RNA functions.

Mouse Leydig cells express multiple P2X receptor subunits.

ATP acts on cellular membranes by interacting with P2X (ionotropic) and P2Y (metabotropic) receptors. Seven homomeric P2X receptors (P2X(1)-P2X(7)) and seven heteromeric receptors (P2X(1/2), P2X(1/4), P2X(1/5), P2X(2/3), P2X(2/6), P2X(4/6), P2X(4/7)) have been described. ATP treatment of Leydig cells leads to an increase in [Ca(2+)](i) and testosterone secretion, supporting the hypothesis that Ca(2+) signaling through purinergic receptors contributes to the process of testosterone secretion in these cells.

FBXO25-associated nuclear domains: a novel subnuclear structure.

Skp1, Cul1, Rbx1, and the FBXO25 protein form a functional ubiquitin ligase complex. Here, we investigate the cellular distribution of FBXO25 and its colocalization with some nuclear proteins by using immunochemical and biochemical approaches. FBXO25 was monitored with affinity-purified antibodies raised against the recombinant fragment spanning residues 2-62 of the FBXO25 sequence.

The N-terminal region of eukaryotic translation initiation factor 5A signals to nuclear localization of the protein.

The eukaryotic translation initiation factor 5A (eIF5A) is a ubiquitous protein of eukaryotic and archaeal organisms which undergoes hypusination, a unique post-translational modification. We have generated a polyclonal antibody against murine eIF5A, which in immunocytochemical assays in B16-F10 cells revealed that the endogenous protein is preferentially localized to the nuclear region. We therefore analyzed possible structural features present in eIF5A proteins that could be responsible for that characteristic.

Ubiquitin-ligase and deubiquitinating gene expression in stretched rat skeletal muscle.

In order to gain insight into intracellular mechanisms involved in longitudinal growth of skeletal muscle, we determined gene expression of ubiquitin-ligases (MAFbx/atrogin-1, E3 alpha, and MuRF-1) and deubiquitinating enzymes (UBP45, UBP69, and USP28) at different time-points (24, 48, and 96 h) of continuous stretch of the soleus and tibialis anterior (TA) muscles. In the soleus, real-time polymerase chain reaction (PCR) showed that MAFbx/atrogin-1, E3 alpha, and MuRF-1 gene expression was downregulated, peaking at 24-48 h. Gene expression of all deubiquitinating enzymes increased with continuous stretch of soleus.

FBXO25, an F-box protein homologue of atrogin-1, is not induced in atrophying muscle.

Atrogin-1/MAFbx/FBXO32 is a muscle-specific ubiquitin-ligase (E3) that is dramatically increased in atrophying muscle. Here, we have investigated the functional relationship between atrogin-1 and FBXO25 which shares 65% amino acid identity. Using a RT-PCR, we demonstrated that FBXO25 is highly expressed in brain, kidney, and intestine, whereas atrogin-1 expression is largely restricted to striate muscle.