Family Of Regulatory Proteins Research Articles

Structural basis of fast- and slow-severing actin–cofilactin boundaries

Members of the ADF/cofilin family of regulatory proteins bind actin filaments cooperatively, locally change actin subunit conformation and orientation, and sever filaments at “boundaries” between bare and cofilin-occupied segments. A cluster of bound cofilin introduces two distinct classes of boundaries due to the intrinsic polarity of actin filaments, one at the “pointed” end side and the other at the “barbed” end-side of the cluster; severing occurs more readily at the pointed end side of the cluster (“fast-severing” boundary) than the barbed end side (“slow-severing” boundary). A recent electron-cryomicroscopy (cryo-EM) model of the slow-severing boundary revealed structural “defects” at the interface that potentially contribute to severing. However, the structure of the fast-severing boundary remains uncertain. Here, we use extensive molecular dynamics simulations to produce atomic resolution models of both severing boundaries. Our equilibrated simulation model of the slow-severing boundary is consistent with the cryo-EM structural model. Simulations indicate that actin subunits at both boundaries adopt structures intermediate between those of bare and cofilin-bound actin subunits. These “intermediate” states have compromised intersubunit contacts, but those at the slow-severing boundary are stabilized by cofilin bridging interactions, accounting for its lower fragmentation probability. Simulations where cofilin proteins are removed from cofilactin filaments favor a mechanism in which a cluster of two contiguously bound cofilins is needed to fully stabilize the cofilactin conformation, promote cooperative binding interactions, and accelerate filament severing. Together, these studies provide a molecular-scale foundation for developing coarse-grained and theoretical descriptions of cofilin-mediated actin filament severing.

Microtubule-associated proteins (MAPs) in microtubule cytoskeletal dynamics and spermatogenesis.

The microtubule (MT) cytoskeleton in Sertoli cells, a crucial cellular structure in the seminiferous epithelium of adult mammalian testes that supports spermatogenesis, was studied morphologically decades ago. However, its biology, in particular the involving regulatory biomolecules and the underlying mechanism(s) in modulating MT dynamics, are only beginning to be revealed in recent years. This lack of studies in delineating the biology of MT cytoskeletal dynamics undermines other studies in the field, in particular the plausible therapeutic treatment and management of male infertility and fertility since studies have shown that the MT cytoskeleton is one of the prime targets of toxicants. Interestingly, much of the information regarding the function of actin-, MT- and intermediate filament-based cytoskeletons come from studies using toxicant models including some genetic models. During the past several years, there have been some advances in studying the biology of MT cytoskeleton in the testis, and many of these studies were based on the use of pharmaceutical/toxicant models. In this review, we summarize the results of these findings, illustrating the importance of toxicant/pharmaceutical models in unravelling the biology of MT dynamics, in particular the role of microtubule-associated proteins (MAPs), a family of regulatory proteins that modulate MT dynamics but also actin- and intermediate filament-based cytoskeletons. We also provide a timely hypothetical model which can serve as a guide to design functional experiments to study how the MT cytoskeleton is regulated during spermatogenesis through the use of toxicants and/or pharmaceutical agents.

Bclw Overexpression Predicts Aggressive Disease in B-Cell Lymphomas

B-cell lymphomas encompass a phenotypically and genetically heterogenous subgroup within hematologic malignancies. Despite this heterogeneity, the ability to evade apoptosis is a unifying feature across B-cell lymphomas, and alterations within the Bcl-2 family of apoptosis regulatory proteins is a key mechanism for this evasion. While overexpression of the anti-apoptotic Bcl-2 family member BCL2 has been widely described in multiple B-cell lymphomas, altered expression of other anti-apoptotic proteins within this family, including BCLX, MCL1, A1 and, in particular, BCLW has been under-investigated. This is highlighted by clinical trials of the BCL2 inhibitor, venetoclax, which found poor single agent activity in B-cell lymphomas that were thought to be highly BCL2-dependent. Therefore, we investigated the contributions of anti-apoptotic Bcl-2 proteins in B-cell lymphomas. Analysis of gene expression profiling datasets of patient samples of major B-cell lymphoma subtypes as compared to normal B-cells demonstrated differential overexpression of anti-apoptotic Bcl-2 proteins, with BCL2, BCLX and BCLW being significantly overexpressed in multiple B-cell lymphoma subtypes. Focusing on aggressive B-cell lymphoma subtypes, BCLW was consistently overexpressed across all major B-cell lymphoma subtypes. Notably, BCLW overexpression was maintained in high grade follicular lymphoma compared to low grade, whereas BCL2 levels decreased as grade increased. These findings indicate that BCLW overexpression is selected for in more aggressive B-cell lymphoma subtypes. BCLW overexpression in aggressive B-cell lymphoma cell lines conferred resistance to the non-specific BH3 mimetic navitoclax as well as to venetoclax. Further, analysis of diffuse large B-cell lymphoma (DLBCL) cell lines demonstrated that the combination of high BCLW/low BCL2 in GCB DLBCL and high BCLW/moderate BCL2 in non-GCB DLBCL is also associated with decreased navitoclax sensitivity, suggesting that high BCLW may confer treatment resistance. In accordance with this, analysis of patient outcomes in DLBCL demonstrates that patients exhibiting high BCLW levels with low BCL2 levels have poorer survival than those with low BCLW. Moreover, Cox regression analysis showed BCLW was an independent determinant of overall survival in DLBCL. Together, our results indicate that BCLW predicts for more aggressive disease in B-cell lymphomas and increased resistance to therapy. Disclosures Eischen: AbbVie Inc.:Research Funding.

Preclinical Development of MGC018, a Duocarmycin-based Antibody–drug Conjugate Targeting B7-H3 for Solid Cancer

B7-H3, also referred to as CD276, is a member of the B7 family of immune regulatory proteins. B7-H3 is overexpressed on many solid cancers, including prostate cancer, renal cell carcinoma, melanoma, squamous cell carcinoma of the head and neck, non-small cell lung cancer, and breast cancer. Overexpression of B7-H3 is associated with disease severity, risk of recurrence and reduced survival. In this article, we report the preclinical development of MGC018, an antibody-drug conjugate targeted against B7-H3. MGC018 is comprised of the cleavable linker-duocarmycin payload, valine-citrulline-seco duocarmycin hydroxybenzamide azaindole (vc-seco-DUBA), conjugated to an anti-B7-H3 humanized IgG1/kappa mAb through reduced interchain disulfides, with an average drug-to-antibody ratio of approximately 2.7. MGC018 exhibited cytotoxicity toward B7-H3-positive human tumor cell lines, and exhibited bystander killing of target-negative tumor cells when cocultured with B7-H3-positive tumor cells. MGC018 displayed potent antitumor activity in preclinical tumor models of breast, ovarian, and lung cancer, as well as melanoma. In addition, antitumor activity was observed toward patient-derived xenograft models of breast, prostate, and head and neck cancer displaying heterogeneous expression of B7-H3. Importantly, MGC018 exhibited a favorable pharmacokinetic and safety profile in cynomolgus monkeys following repeat-dose administration. The antitumor activity observed preclinically with MGC018, together with the positive safety profile, provides evidence of a potentially favorable therapeutic index and supports the continued development of MGC018 for the treatment of solid cancers. GRAPHICAL ABSTRACT: http://mct.aacrjournals.org/content/molcanther/19/11/2235/F1.large.jpg.

Effects of 3,4-dichloroaniline (3,4-DCA) and 4,4′-methylenedianiline (4,4′-MDA) on sex hormone regulation and reproduction of adult zebrafish (Danio rerio)

3,4-dichloroaniline (3,4-DCA) and 4,4′-methylenedianiline (4,4′-MDA) have been widely used in manufacture of many industrial and consumer products, and hence often detected in aquatic environment. Reproductive toxicity of aniline and its derivatives in aquatic organisms has been suggested, however, knowledge on the endocrine disruption potentials and toxicological consequences of both anilines are not well understood, especially in fish. In this study, we aimed to understand the effects of 3,4-DCA and 4,4′-MDA on sex hormone regulation and reproduction of adult zebrafish (Danio rerio). Following 21 d exposure, significant decreases of the reproduction were observed at 0.38 mg/L 3,4-DCA, and 4.6 mg/L 4,4′-MDA. Moreover, plasma concentrations of testosterone (T) and 17β-estradiol (E2) level were significantly decreased in both male and female fish following the exposure. The sex hormone changes could be explained by the regulatory changes of the genes along the hypothalamic-pituitary-gonadal (HPG) axis, including significant down-regulation of steroidogenic acute regulatory protein (star) and cytochrome P450 family 19 subfamily A (cyp19a) genes in the gonad. Moreover, inhibition of gonadotropin hormone signaling and prostaglandin-endoperoxide synthase 2 (ptgs2) gene expression were observed, suggesting potential disruption of oocyte maturation and ovulation by the exposure. Our observations indicate that 3,4-DCA and 4,4′-MDA can impair reproduction of zebrafish potentially through disruption of steroid hormone synthesis and ovulation.

Reversible regulation of conjugation of Bacillus subtilis plasmid pLS20 by the quorum sensing peptide responsive anti-repressor RappLS20.

Quorum sensing plays crucial roles in bacterial communication including in the process of conjugation, which has large economical and health-related impacts by spreading antibiotic resistance. The conjugative Bacillus subtilis plasmid pLS20 uses quorum sensing to determine when to activate the conjugation genes. The main conjugation promoter, Pc, is by default repressed by a regulator RcopLS20 involving DNA looping. A plasmid-encoded signalling peptide, Phr*pLS20, inactivates the anti-repressor of RcopLS20, named RappLS20, which belongs to the large group of RRNPP family of regulatory proteins. Here we show that DNA looping occurs through interactions between two RcopLS20 tetramers, each bound to an operator site. We determined the relative promoter strengths for all the promoters involved in synthesizing the regulatory proteins of the conjugation genes, and constructed an in vivo system uncoupling these regulatory genes to show that RappLS20 is sufficient for activating conjugation in vivo. We also show that RappLS20 actively detaches RcopLS20 from DNA by preferentially acting on the RcopLS20 molecules involved in DNA looping, resulting in sequestration but not inactivation of RcopLS20. Finally, results presented here in combination with our previous results show that activation of conjugation inhibits competence and competence development inhibits conjugation, indicating that both processes are mutually exclusive.

Loss of mDia1 and Fhod1 impacts platelet formation but not platelet function

An organized and dynamic cytoskeleton is required for platelet formation and function. Formins are a large family of actin regulatory proteins which are also able to regulate microtubule dynamics. There are four formin family members expressed in human and mouse megakaryocytes and platelets. We have previously shown that the actin polymerization activity of formin proteins is required for cytoskeletal dynamics and platelet spreading using a small molecule inhibitor. In the current study, we analyze transgenic mouse models deficient in two of these proteins, mDia1 and Fhod1, along with a model lacking both proteins. We demonstrate that double knockout mice display macrothrombocytopenia which is due to aberrant megakaryocyte function and a small decrease in platelet lifespan. Platelet function is unaffected by the loss of these proteins. This data indicates a critical role for formins in platelet and megakaryocyte function.

F-Box Family Genes, LTSF1 and LTSF2, Regulate Low-Temperature Stress Tolerance in Pepper (Capsicum chinense).

The F-box proteins belong to a family of regulatory proteins that play key roles in the proteasomal degradation of other proteins. Plant F-box proteins are functionally diverse, and the precise roles of many such proteins in growth and development are not known. Previously, two low-temperature-sensitive F-box protein family genes (LTSF1 and LTSF2) were identified as candidates responsible for the sensitivity to low temperatures in the pepper (Capsicum chinense) cultivar ‘sy-2’. In the present study, we showed that the virus-induced gene silencing of these genes stunted plant growth and caused abnormal leaf development under low-temperature conditions, similar to what was observed in the low-temperature-sensitive ‘sy-2’ line. Protein–protein interaction analyses revealed that the LTSF1 and LTSF2 proteins interacted with S-phase kinase-associated protein 1 (SKP1), part of the Skp, Cullin, F-box-containing (SCF) complex that catalyzes the ubiquitination of proteins for degradation, suggesting a role for LTSF1 and LTSF2 in protein degradation. Furthermore, transgenic Nicotiana benthamiana plants overexpressing the pepper LTSF1 gene showed an increased tolerance to low-temperature stress and a higher expression of the genes encoding antioxidant enzymes. Taken together, these results suggest that the LTSF1 and LTSF2 F-box proteins are a functional component of the SCF complex and may positively regulate low-temperature stress tolerance by activating antioxidant-enzyme activities.

ROLE OF CYCLIN D1 IN THE MECHANISMS OF TAMOXIFEN RESISTANCE

Hormone-receptor positive breast cancer is the most common molecular subtype and represents 60–75 % of all breast cancers (BC). The presence of specific molecular targets such as the estrogen/progesterone receptor determines the use of hormone therapy for patients with this subtype. Tamoxifen, a selective estrogen receptor modulator, remains the first adjuvant treatment choice for the hormone-receptor positive BC patients. However, tamoxifen resistance is the major limitation of its efficacy. In this regard, the study of drug resistance mechanisms as well as search for biological prognostic markers of tamoxifen efficacy is very important. Cyclin D1 is a representative of the regulatory protein family, which plays a central role in the cell cycle regulation. The data on the association between cyclin D1 and estrogen-dependent signaling as well as the characteristics of CCND1 gene and its most studied polymorphic loci, were presented. The prognostic significance of cyclin D1 in hormone-receptor positive BC receptor-positive breast cancer was described. The experimental and clinical studies data on the association between the cyclin D1 expression level and tamoxifen efficacy are analyzed. Current approaches to overcoming hormone resistance based on cyclin D1 studies were considered.

A genetic variant in the promoter of CD46 is associated with the risk and prognosis of hepatocellular carcinoma.

CD46 (also known as membrane cofactor protein), which is a member of the membrane-bound complement regulatory protein family, has been reported to cause cancer cells to escape complement-dependent cytotoxicity. However, the association between CD46 polymorphisms and the risk of hepatocellular carcinoma (HCC) has not been investigated. This two-stage association study was conducted to assess the relationship between the tagging single nucleotide polymorphisms (tagSNPs) of CD46 and HCC risk and prognosis. A series of functional analyses were performed to study the underlying mechanisms. Among the eight tagSNPs, rs2796267 (P = .003) and rs2796268 (P = .011) were found to modify HCC risk in the discovery set. Only rs2796267 (P < .0001) was confirmed to be associated with HCC susceptibility in the validation set. Compared with the wild-type AA genotype, the GG genotype significantly increased the HCC risk (adjusted odds ratio [OR] = 2.03; 95% confidence interval [CI], 1.34-3.08; P = .001). Moreover, subgroups analysis suggested a positive correlation among male and younger patients, especially among drinkers, smokers, and hepatitis B surface antigen-positive individuals. In functional analyses, we found that the rs2796267 G allele in the promoter region of CD46 could increase the expression of CD46 by affecting the binding affinity of STAT5a. Furthermore, Cox regression analysis revealed that the rs2796267 AG/GG genotype was significantly associated with worse prognosis of resected patients with HCC (hazard ratio = 2.27; 95% CI, 1.27-4.05; P = .006). These results suggest that the CD46 rs2796267 polymorphism may contribute to susceptibility and prognosis of HCC by altering promoter activity.

Unconservative_15_2570409 suppresses progesterone receptor expression in the granulosa cells of Hu sheep

Female fertility potential depends on the number of mature follicles; however, the underlying molecular mechanisms remain unclear. Based on previously generated miRNA and mRNA sequencing data of healthy ovarian follicles (>5 mm in diameter) isolated from Hu sheep with different prolificacy, we investigated the roles of a novel miRNA (unconservative_15_2570409) and the progesterone receptor (PGR) gene in follicular development. During the periovulatory phase, the expression of unconservative_15_2570409 and PGR was lower and higher, respectively, in the >5 mm follicles of high prolificacy (HP) ewes than in those of low prolificacy (LP) ewes and in the >3 mm follicles than in the smaller follicles of the HP ewes. Subsequently, the granulosa cells (GCs) of Hu sheep were used as an in vitro model. PGR overexpression significantly increased the mRNA expression of steroidogenic acute regulatory protein (StAR), 3-beta-hydroxysteroid dehydrogenase/isomerase (3β-HSD), and cytochrome P450 family 19 subfamily A member 1 (CYP19A1), which promoted the secretion of progesterone (P4) and estradiol (E2). PGR knockdown significantly downregulated the levels of StAR and 3β-HSD mRNA and decreased the production of P4, whereas no effects on CYP19A1 mRNA expression and E2 levels were observed. We also found the negative regulatory effect of unconservative_15_2570409 on the mRNA and protein expression of PGR by targeting the 3ʹ-untranslated region. The regulation of PGR levels resulted in a corresponding change in the ADAMTS1, PPAR-γ, and CTSL gene transcripts, which are important for follicular maturation and ovulation. Additionally, PGR, ADAMTS1, and PPAR-γ were predominantly localized in the GCs. Collectively, our results suggest that by regulating PGR expression and consequently affecting the expression of target genes and steroidogenesis, unconservative_15_2570409 plays a role in follicular development during the periovulatory stage, which provides novel insights into the molecular mechanisms affecting Hu sheep prolificacy.

Pollen food associated syndrome: the newly described Gibberellin Regulated Protein family

Pollen food associated syndrome: the newly described Gibberellin Regulated Protein family

SAT-284 Musashi Exerts Translational Control Within Anterior Pituitary Cells of the POU1F1 Lineage

The activation of transcription factor Pou1f1 at embryonic day 13 gives rise to the pituitary populations of somatotropes, lactotropes, and thyrotropes and these populations maintain expression of Pou1f1 throughout life. The Musashi family of RNA regulatory proteins is known to regulate stem cell fate by repressing translation of target mRNAs needed for differentiation. Previously our lab has shown that female Lepr-null somatotropes have reduced POU1F1 protein levels but do not have changes in Pou1f1 mRNA expression. Stimulation with leptin increased the POU1F1 protein levels 3-fold, but did not change Pou1f1 mRNA suggesting a post-transcriptional mechanism for leptin’s regulation of Pou1f1. An in silico analysis indicated the presence a number of potential regulatory elements (MBEs) within the Pou1f1 mRNA 3’ UTR, including 8 consensus Musashi binding elements. Interestingly, we found musashi mRNA and protein levels were increased in Lepr-null somatotropes. This suggested that leptin regulates the expression of musashi in somatotrope populations and may be a candidate translational regulator of the Pou1f1 mRNA. We verified that MSI binds directly to the Pou1f1 mRNA 3’ UTR MBEs by EMSA in vitro and exerts translational repression (using reporter mRNA assays in transfected cell populations). Single cell RNA sequencing of pituitary cells from control male and female mice indicates that MSI and Pou1f1 mRNAs are co-expressed in somatotropes, lactotropes as well as thyrotropes. Immunocytochemical analyses confirmed that Musashi protein is present in mixed and purified somatotrope populations. Furthermore, immunoprecipitation with Musashi1 antibody showed a 5-fold enrichment of Pou1f1 mRNA in control female mouse pituitaries. These findings point to a critical in vivo role for Musashi-mediated mRNA translational regulation within the Pou1f1 lineage and specifically in the control of somatotrope maturation and response to metabolic cues.

Neuronal Nitric Oxide Synthase Associated Protein: Nos1ap mediates Sympathoexcitation through Paraventricular Nucleus of the Hypothalamus

Exaggerated sympathoexcitation is associated with multiple disorders, including hypertension, heart failure, diabetes leading to various cardiovascular complications. Within the paraventricular nucleus of the hypothalamus (PVN), nitric oxide (NO•) is synthesized by neuronal nitric oxide synthase (NOS1) and acts as a non‐conventional neurotransmitter that inhibits neuronal firing and consequent sympathetic outflow. NOS1 is tethered to N‐methyl D‐aspartate receptor (NMDAR) channels harboring NMDAR subunit 2B by the scaffolding protein postsynaptic density 95 (PSD95). Activation of the NMDAR at the synaptic membrane initiates a Ca2+ influx that stimulates the production of NO•. NOS1 adaptor protein (Nos1ap) competes with PSD95 for NOS1 binding and thus influences the production of NO•. We investigated the effect of over‐expressing Nos1ap in the PVN on sympathetic outflow using Cre recombinase‐conditional Nos1ap‐transgenic (Tg) mice. The Nos1ap Tg mice were microinjected with lentiviral expressing Cre‐GFP or GFP bilaterally into the PVN following our standardized method, referred to as CAPON‐OE and Control, respectively. Two weeks of post‐viral administration, the sympathetic outflow, was evaluated. CAPON‐OE mice displayed a significantly elevated urinary excretion of norepinephrine, an index of overall sympathetic outflow compared to Control (0.64±0.11* vs. 0.17±0.03 ug/day). Basal renal sympathetic nerve activity, measured as a percent of maximal activity was elevated 1.5‐fold in CAPON‐OE (46.09 ± 3.56* vs.31.04 ± 3.24) mice. Furthermore, FosB (a member of the AP‐1 family of transcription regulatory proteins) immunocytochemistry revealed increased expression in the PVN of CAPON‐OE mice when compared to control mice suggesting a chronic activation of PVN neurons after Nos1ap over‐expression. Interestingly, a robust over‐expression of Nos1ap in the PVN of CAPON‐OE (0.49±0.04* vs. 0.21±0.03) compared to control mice does not lead to any significant change in NOS1 expression. However, DAF‐FM staining of PVN slices showed decreased NO• levels in CAPON‐OE mice when compared to control mice suggesting that the decrease in NMDAR‐mediated NOS1 activity due to sequestering of NOS1 by Nos1ap leads to less NO• production. Taken together, our data indicate that specific over‐expression of Nos1ap within the PVN reduces the levels of NO• generated by NOS1, leading to increased sympathetic outflow.Support or Funding InformationSupported by AHA ‐ 14SDG19980007 and NIH grant HL62222.

Conformational control of small GTPases by AMPylation

Posttranslational modifications (PTMs) are important physiological means to regulate the activities and structures of central regulatory proteins in health and disease. Small GTPases have been recognized as important molecules that are targeted by PTMs during infections of mammalian cells by bacterial pathogens. The enzymes DrrA/SidM and AnkX from Legionella pneumophila AMPylate and phosphocholinate Rab1b during infection, respectively. Cdc42 is AMPylated by IbpA from Histophilus somni at tyrosine 32 or by VopS from Vibrio parahaemolyticus at threonine 35. These modifications take place in the important regulatory switch I or switch II regions of the GTPases. Since Rab1b and Cdc42 are central regulators of intracellular vesicular trafficking and of the actin cytoskeleton, their modifications by bacterial pathogens have a profound impact on the course of infection. Here, we addressed the biochemical and structural consequences of GTPase AMPylation and phosphocholination. By combining biochemical experiments and NMR analysis, we demonstrate that AMPylation can overrule the activity state of Rab1b that is commonly dictated by binding to guanosine diphosphate or guanosine triphosphate. Thus, PTMs may exert conformational control over small GTPases and may add another previously unrecognized layer of activity control to this important regulatory protein family.

Disclosing the Potential of the SARP-Type Regulator PapR2 for the Activation of Antibiotic Gene Clusters in Streptomycetes.

Streptomyces antibiotic regulatory protein (SARP) family regulators are well-known activators of antibiotic biosynthesis in streptomycetes. The respective genes occur in various types of antibiotic gene clusters encoding, e.g., for polyketides, ribosomally and non-ribosomally synthesized peptides, or β-lactam antibiotics. We found that overexpression of the SARP-type regulator gene papR2 from Streptomyces pristinaespiralis in Streptomyces lividans leads to the activation of the silent undecylprodigiosin (Red) gene cluster. The activation happens upon the inducing function of PapR2, which takes over the regulatory role of RedD, the latter of which is the intrinsic SARP regulator of Red biosynthesis in S. lividans. Due to the broad abundance of SARP genes in different antibiotic gene clusters of various actinomycetes and the uniform activating principle of the encoded regulators, we suggest that this type of regulator is especially well suited to be used as an initiator of antibiotic biosynthesis in actinomycetes. Here, we report on a SARP-guided strategy to activate antibiotic gene clusters. As a proof of principle, we present the PapR2-driven activation of the amicetin/plicacetin gene cluster in the novel Indonesian strain isolate Streptomyces sp. SHP22-7.

Regulation of aureofuscin production by the PAS-LuxR family regulator AurJ3M

aurJ3M(GenBank:EU697915.1), a 579 bp gene, whose deduced product (192 amino acid) was found to have amino acid sequence homology with some bacterial regulatory proteins. Computer-assisted analysis showed that AurJ3M is PAS-LuxR family regulatory protein, it combines a PAS domain with a helix–turn–helix (HTH) motif of the LuxR type. Gene deletion of aurJ3M from the S.aureofuscus SYAU0709 through gene replacement with the apramycin resistance gene aac (3) IV and the DNA fragment of the replication initiation site sequence OriT resulted in complete loss of aureofuscin production, indicating that AurJ3M is a positive regulator during the aureofuscin biosynthesis.Gene expression analyses in S.aureofuscus SYAU0709 and S.aureofuscus ΔaurJ3M by reverse transcriptase PCR (RT-PCR) indicated there no transcripts for the genes B、C、G、F、S0、S1、D in S.aureofuscus ΔaurJ3M, maintains some transcription of these genes although the levels is low. Transcription was also significantly reduced for gene A, and no difference in the transcription pattern was observed for the genes R、E and H, a similar transcription pattern was also observed for AurJ3M, A and B showed a different transcription pattern, while transcription of gene A in S.aureofuscus ΔaurJ3M when compared to the parental strain, no transcripts could be detected for gene B in the mutant; This result indicates that the deletion of aurJ3M gene doesn't have a polar effect on the transcription of genes located downstream from aurJ3M. In the ΔaurJ3M knockout mutant, except for the transcription of E、H、M and R, the transcription of other genes in the cluster was down-regulated, HPLC shows there no secondary metabolites was produced,aurJ3M has a pathway-specific regulation effect on the biosynthesis of aureofuscin. Aureofuscin had broad application prospects in food preservation, and enriched the resource pool of anti-fungal antibiotics of tetraphenyl macrolide in China.

Regulation of the 20S Proteasome by a Novel Family of Inhibitory Proteins.

Aims: The protein degradation machinery plays a critical role in the maintenance of cellular homeostasis, preventing the accumulation of damaged or misfolded proteins and controlling the levels of regulatory proteins. The 20S proteasome degradation machinery, which predominates during oxidative stress, is able to cleave any protein with a partially unfolded region, however, uncontrolled degradation of the myriad of potential substrates is improbable. This study aimed to identify and characterize the regulatory mechanism that controls 20S proteasome-mediated degradation. Results: Using a bioinformatic screen based on known 20S proteasome regulators, we have discovered a novel family of 20S proteasome regulators, named catalytic core regulators (CCRs). These regulators share structural and sequence similarities, and coordinate the function of the 20S proteasome by affecting the degradation of substrates. The CCRs are involved in the oxidative stress response via Nrf2, organizing into a feed-forward loop regulatory circuit, with some members stabilizing Nrf2, others being induced by Nrf2, and all of them inhibiting the 20S proteasome. Innovation and Conclusion: These data uncover a new family of regulatory proteins that utilize a fine-tuned mechanism to carefully modulate the activity of the 20S proteasome, in particular under conditions of oxidative stress, ensuring its proper functioning by controlling the degradative flux.

Duplicate US1 Genes of Duck Enteritis Virus Encode a Non-essential Immediate Early Protein Localized to the Nucleus

The duplicate US1 genes of duck enteritis virus (DEV) encode a protein with a conserved Herpes_IE68 domain, which was found to be closely related to the herpes virus immediate early regulatory protein family and is highly conserved among counterparts encoded by Herpes_IE68 genes. Previous studies found the homologous proteins HSV-1 ICP22 and VZV ORF63/ORF70 to be critical for virus transcription and replication. However, little is known about the DEV ICP22 protein. In this paper, we describe the characteristics of this protein based on pharmacological experiments, real-time quantitative Polymerase Chain Reaction, Western blot, and immunofluorescence assays. We also investigate the role of the protein in DEV replication via mutation of US1. As a result, we found that the DEV ICP22 protein is a non-essential immediate early protein predominantly located in the nucleus of infected DEF cells and that DEV replication is impaired by US1 deletion. We also found that ICP22 contains a classical nuclear localization signal (NLS) at 305-312AA, and ICP22 cannot enter the nucleus by itself after mutating residue 309.

Beneficial Effects of SREBP Decoy Oligodeoxynucleotide in an Animal Model of Hyperlipidemia.

Hyperlipidemia is a chronic disorder that plays an important role in the development of cardiovascular diseases, type II diabetes, atherosclerosis, hypertension, and non-alcoholic fatty liver disease. Hyperlipidemias have created a worldwide health crisis and impose a substantial burden not only on personal health but also on societies and economies. Transcription factors in the sterol regulatory element binding protein (SREBP) family are key regulators of the lipogenic genes in the liver. SREBPs regulate lipid homeostasis by controlling the expression of a range of enzymes required for the synthesis of endogenous cholesterol, fatty acids, triacylglycerol, and phospholipids. Thereby, SREBPs have been considered as targets for the treatment of metabolic diseases. The aim of this study was to investigate the beneficial functions and the possible underlying molecular mechanisms of SREBP decoy ODN, which is a novel inhibitor of SREBPs, in high-fat diet (HFD)-fed hyperlipidemic mice. Our studies using HFD-induced hyperlipidemia animal model revealed that SREBB decoy ODN inhibited the increased expression of fatty acid synthetic pathway, such as SREBP-1c, FAS, SCD-1, ACC1, and HMGCR. In addition, SREBP decoy ODN decreased pro-inflammatory cytokines, including TNF-α, IL-1β, IL-8, and IL-6 expression. These results suggest that SREBP decoy ODN exerts its anti-hyperlipidemia effects in HFD-induced hyperlipidemia mice by regulating their lipid metabolism and inhibiting lipogenesis through inactivation of the SREPB pathway.