Spectrum collapse in a 7-core Yb-doped fiber laser with an array of fs-inscribed fiber Bragg gratings.

Femtosecond inscription of fiber Bragg gratings (FBGs) in each core of a cladding-pumped seven-core Yb-doped fiber enables efficient (≈70%) 1064-nm lasing in a robust all-fiber scheme with ≈33 W power, nearly the same for uncoupled and coupled cores. However, the output spectrum is quite different: without coupling, seven individual lines corresponding to the in-core FBG reflection spectra sum up into a broad (0.22 nm) total spectrum, whereas the multiline spectrum collapses into a single narrow line at strong coupling. The developed model shows that the coupled-core laser generates coherent superposition of supermodes at the wavelength corresponding to the geometric mean of the individual FBG spectra, whereas the generated laser line broadens, with a power (0.04-0.12 nm) like the single-core mode of a seven-times larger effective area.

Multifidelity Statistical Machine Learning for Molecular Crystal Structure Prediction.

The prediction of crystal structures from first-principles requires highly accurate energies for large numbers of putative crystal structures. High accuracy of solid state density functional theory (DFT) calculations is often required, but hundreds or more structures can be present in the low energy region of interest, so that the associated computational costs are prohibitive. Here, we apply statistical machine learning to predict expensive hybrid functional DFT (PBE0) calculations using a multifidelity approach to re-evaluate the energies of crystal structures predicted with an inexpensive force field. The method uses an autoregressive Gaussian process, making use of less expensive GGA DFT (PBE) calculations to bridge the gap between the force field and PBE0 energies. The method is benchmarked on the crystal structure landscapes of three small, hydrogen-bonded organic molecules and shown to produce accurate predictions of energies and crystal structure ranking using small numbers of the most expensive calculations; the PBE0 energies can be predicted with errors of less than 1 kJ mol-1 with between 4.2 and 6.8% of the cost of the full calculations. As the model that we have developed is probabilistic, we discuss how the uncertainties in predicted energies impact the assessment of the energetic ranking of crystal structures.

Mdm2 and MdmX RING Domains Play Distinct Roles in the Regulation of p53 Responses: A Comparative Study of Mdm2 and MdmX RING Domains in U2OS Cells.

Dysfunction of the tumor suppressor p53 occurs in most human cancers. Mdm2 and MdmX are homologous proteins from the Mdm (Murine Double Minute) protein family, which play a critical role in p53 inactivation and degradation. The two proteins interact with one another via the intrinsic RING (Really Interesting New Gene) domains to achieve the negative regulation of p53. The downregulation of p53 is accomplished by Mdm2-mediated p53 ubiquitination and proteasomal degradation through the ubiquitin proteolytic system and by Mdm2 and MdmX mediated inhibition of p53 transactivation. To investigate the role of the RING domain of Mdm2 and MdmX, an analysis of the distinct functionalities of individual RING domains of the Mdm proteins on p53 regulation was conducted in human osteosarcoma (U2OS) cell line. Mdm2 RING domain was observed mainly localized in the cell nucleus, contrasting the localization of MdmX RING domain in the cytoplasm. Mdm2 RING was found to possess an endogenous E3 ligase activity, whereas MdmX RING did not. Both Mdm2 and MdmX RING domains were able to dimerize with endogenous full-length Mdm2 and MdmX protein and affect their cellular function. The results showed that overexpression of the Mdm2 or MdmX RING domains interfered with the endogenous full-length Mdm2 and MdmX activity and resulted in p53 stabilization and p53 target gene activation. However, both Mdm RING domains showed oncogenic activity in a colony formation assay, suggesting that the Mdm RING domains possess p53-independent oncogenic properties. This study highlights the distinct structural and functional traits of the RING domain of Mdm2 and MdmX and characterized their role in cellular responses through interfering with p53 dependent signaling pathway.

The Legionella pneumophila effector Ceg4 is a phosphotyrosine phosphatase that attenuates activation of eukaryotic MAPK pathways.

Host colonization by Gram-negative pathogens often involves delivery of bacterial proteins called "effectors" into the host cell. The pneumonia-causing pathogen Legionella pneumophila delivers more than 330 effectors into the host cell via its type IVB Dot/Icm secretion system. The collective functions of these proteins are the establishment of a replicative niche from which Legionella can recruit cellular materials to grow while evading lysosomal fusion inhibiting its growth. Using a combination of structural, biochemical, and in vivo approaches, we show that one of these translocated effector proteins, Ceg4, is a phosphotyrosine phosphatase harboring a haloacid dehalogenase-hydrolase domain. Ceg4 could dephosphorylate a broad range of phosphotyrosine-containing peptides in vitro and attenuated activation of MAPK-controlled pathways in both yeast and human cells. Our findings indicate that L. pneumophila's infectious program includes manipulation of phosphorylation cascades in key host pathways. The structural and functional features of the Ceg4 effector unraveled here provide first insight into its function as a phosphotyrosine phosphatase, paving the way to further studies into L. pneumophila pathogenicity.

Durable shape sensor based on FBG array inscribed in polyimide-coated multicore optical fiber.

The paper presents a novel three-dimensional quasi-continuous shape sensor based on an FBG array inscribed by femtosecond laser pulses into a 7-core optical fiber with a polyimide protective coating. The measured bending sensitivity of individual FBGs ranges from 0.046 nm/m-1 to 0.049 nm/m-1. It is shown that the sensor allows for reconstructing 2- and 3-dimensional shapes with high accuracy. Due to the high value of the core aperture and individual calibration of each FBG we were able to measure the smallest reported bending radii down to 2.6 mm with a record accuracy of ∼1%. Moreover, we investigate the magnitude of the errors of curves reconstruction and errors associated with measurement of curvature radii in the range from 2.6 to 500 mm. The main factors affecting the accuracy of measurements are also discussed. The temperature resistance of both the inscribed FBG structures and of the protective coating, along with the high mechanical strength of the polyimide, makes it possible to use the sensor in harsh environments or in medical and composite material applications.

UbE2E1/UBCH6 Is a Critical in Vivo E2 for the PRC1-catalyzed Ubiquitination of H2A at Lys-119.

UbE2E1/UbcH6 is an E2 ubiquitin-conjugating enzyme that is regulated by USP7. We identified UbE2E1 as a novel component of Polycomb repressive complex 1 (PRC1), the E3 ligase complex responsible for histone H2A ubiquitination and gene silencing. We demonstrate that UbE2E1 is critical for the monoubiquitination of H2A at residue Lys-119 (uH2AK119) through its association with the PRC1 complex. UbE2E1 interacts with PRC1 subunits including Ring1A and Ring1B. Overexpression of UbE2E1 results in increased levels of uH2AK119, whereas overexpression of catalytically inactive UbE2E1_C131A or UbE2E1 knockdown results in decreased levels of uH2AK119. The down-regulation of H2A ubiquitination by loss of function of UbE2E1 is correlated with alleviated p16INK4a promoter repression and induced growth inhibition in HCT116 cells. These results are specific to UbE2E1 as knockdown of UbE2D E2s does not show any effect on uH2AK119. We extended the UbE2E1 regulation of uH2AK119 to USP7 and showed that USP7 is also a key regulator for monoubiquitination at H2A Lys-119 as both knockdown and deletion of USP7 results in decreased levels of uH2AK119. This study reveals that UbE2E1 is an in vivo E2 for the PRC1 ligase complex and thus plays an important role in the regulation of H2A Lys-119 monoubiquitination.

Identification of Kaposi Sarcoma Herpesvirus (KSHV) vIRF1 Protein as a Novel Interaction Partner of Human Deubiquitinase USP7.

Viral interferon regulatory factor 1 (vIRF1), a Kaposi sarcoma herpesvirus protein, destabilizes p53 by inhibiting p53 acetylation and Hdm2 phosphorylation. This leads to increased ubiquitination and degradation of p53 by Hdm2, which cripples the cellular p53-mediated antiviral response. Ubiquitin-specific protease 7 (USP7) deubiquitinates p53 and Hdm2 and regulates their stability. We identified an EGPS consensus sequence in vIRF1, which is identical to that found in Epstein-Barr virus nuclear antigen 1 (EBNA1) that interacts with the N-terminal domain of USP7 (USP7-NTD). GST pulldown assays demonstrated that vIRF1 interacts with USP7-NTD via its EGPS motif. NMR heteronuclear single quantum correlation (HSQC) analysis revealed chemical perturbations after titration of USP7-NTD with vIRF1 (44)SPGEGPSGTG(53) peptide. In contrast, these perturbations were reduced with a mutant vIRF1 peptide, (44)SPGEGPAGTG(53). Fluorescence polarization analysis indicated that the vIRF1 peptide interacted with USP7-NTD with a Kd of 2.0 µm. The crystal structure of the USP7-NTD·vIRF1 peptide complex revealed an identical mode of binding as that of the EBNA1 peptide to USP7-NTD. We also showed that USP7 interacts with vIRF1 in U2OS cells. Decreased levels of p53, but not Hdm2 or ataxia telangiectasia-mutated (ATM), were seen after expression of vIRF1, but not with a vIRF1 mutant protein. Our results support a new role for vIRF1 through deregulation of the deubiquitinating enzyme USP7 to inhibit p53-mediated antiviral responses.

The environment shapes microbial enzymes: five cold-active and salt-resistant carboxylesterases from marine metagenomes.

Most of the Earth's biosphere is cold and is populated by cold-adapted microorganisms. To explore the natural enzyme diversity of these environments and identify new carboxylesterases, we have screened three marine metagenome gene libraries for esterase activity. The screens identified 23 unique active clones, from which five highly active esterases were selected for biochemical characterization. The purified metagenomic esterases exhibited high activity against α-naphthyl and p-nitrophenyl esters with different chain lengths. All five esterases retained high activity at 5 °C indicating that they are cold-adapted enzymes. The activity of MGS0010 increased more than two times in the presence of up to 3.5 M NaCl or KCl, whereas the other four metagenomic esterases were inhibited to various degrees by these salts. The purified enzymes showed different sensitivities to inhibition by solvents and detergents, and the activities of MGS0010, MGS0105 and MGS0109 were stimulated three to five times by the addition of glycerol. Screening of purified esterases against 89 monoester substrates revealed broad substrate profiles with a preference for different esters. The metagenomic esterases also hydrolyzed several polyester substrates including polylactic acid suggesting that they can be used for polyester depolymerization. Thus, esterases from marine metagenomes are cold-adapted enzymes exhibiting broad biochemical diversity reflecting the environmental conditions where they evolved.

A site-directed mutagenesis study of the MdmX RING domain.

Mdm2 and MdmX are important negative regulators of the tumor suppressor p53. Structurally homologous Mdm2 and MdmX inhibit p53 by directly blocking p53 transcriptional activation. Mdm2 also modifies and targets p53 for 26S proteasome dependent protein degradation through E3 ligase activity mediated by its C-terminal RING domain. However, MdmX lacks intrinsic E3 ligase activity and fails to catalyze ubiquitination of p53 despite containing a conserved RING domain. Thus, a comparative structural analysis between the Mdm2 and MdmX RING domains offers a unique way to elucidate the distinct functions of the two proteins in ubiquitination. We performed site-directed mutagenesis of the MdmX RING domain and found that the substitution of the residue N448 for cysteine and the substitution of the residue K478 for arginine granted MdmX RING domain ubiquitination activity. The structural analysis of the Mdm2 and MdmX RING domains revealed that the residue C449 of Mdm2 (structurally homologous to MdmX RING N448) located at the Mdm2 RING dimer interface is critical for the stability of the RING dimer structure, while the residue R479 (structurally homologous to MdmX RING K478) plays a role in recruiting and activating the ubiquitin E2 conjugating enzyme. This study provides new insight into the molecular mechanism of Mdm2 RING domain mediated ubiquitination.

Structure-guided optimization of protein kinase inhibitors reverses aminoglycoside antibiotic resistance.

Activity of the aminoglycoside phosphotransferase APH(3')-Ia leads to resistance to aminoglycoside antibiotics in pathogenic Gram-negative bacteria, and contributes to the clinical obsolescence of this class of antibiotics. One strategy to rescue compromised antibiotics such as aminoglycosides is targeting the enzymes that confer resistance with small molecules. We demonstrated previously that ePK (eukaryotic protein kinase) inhibitors could inhibit APH enzymes, owing to the structural similarity between these two enzyme families. However, limited structural information of enzyme-inhibitor complexes hindered interpretation of the results. In addition, cross-reactivity of compounds between APHs and ePKs represents an obstacle to their use as aminoglycoside adjuvants to rescue aminoglycoside antibiotic activity. In the present study, we structurally and functionally characterize inhibition of APH(3')-Ia by three diverse chemical scaffolds, anthrapyrazolone, 4-anilinoquinazoline and PP (pyrazolopyrimidine), and reveal distinctions in the binding mode of anthrapyrazolone and PP compounds to APH(3')-Ia compared with ePKs. Using this observation, we identify PP derivatives that select against ePKs, attenuate APH(3')-Ia activity and rescue aminoglycoside antibiotic activity against a resistant Escherichia coli strain. The structures described in the present paper and the inhibition studies provide an important opportunity for structure-based design of compounds to target aminoglycoside phosphotransferases for inhibition, potentially overcoming this form of antibiotic resistance.

Structure and activity of the cold-active and anion-activated carboxyl esterase OLEI01171 from the oil-degrading marine bacterium Oleispira antarctica.

The uncharacterized α/ß-hydrolase protein OLEI01171 from the psychrophilic marine bacterium Oleispira antarctica belongs to the PF00756 family of putative esterases, which also includes human esterase D. In the present paper we show that purified recombinant OLEI01171 exhibits high esterase activity against the model esterase substrate α-naphthyl acetate at 5-30°C with maximal activity at 15-20°C. The esterase activity of OLEI01171 was stimulated 3-8-fold by the addition of chloride or several other anions (0.1-1.0 M). Compared with mesophilic PF00756 esterases, OLEI01171 exhibited a lower overall protein thermostability. Two crystal structures of OLEI01171 were solved at 1.75 and 2.1 Å resolution and revealed a classical serine hydrolase catalytic triad and the presence of a chloride or bromide ion bound in the active site close to the catalytic Ser148. Both anions were found to co-ordinate a potential catalytic water molecule located in the vicinity of the catalytic triad His257. The results of the present study suggest that the bound anion perhaps contributes to the polarization of the catalytic water molecule and increases the rate of the hydrolysis of an acyl-enzyme intermediate. Alanine replacement mutagenesis of OLEI01171 identified ten amino acid residues important for esterase activity. The replacement of Asn225 by lysine had no significant effect on the activity or thermostability of OLEI01171, but resulted in a detectable increase of activity at 35-45°C. The present study has provided insight into the molecular mechanisms of activity of a cold-active and anion-activated carboxyl esterase.

Salmonella mutant strains resistant to herbicides - Acetohydroxyacid synthase inhibitors and their use at the Ames test.

Cytotoxicity of some pesticides is a disadvantage for the Salmonella/microsome assay with regard to the equivalence assessment of pesticide technical grade active ingredients to the original products and detection of low-level impurities. The technical grade active ingredients (TGAIs) of pesticides from certain chemical classes were found to be toxic for Salmonella typhimurium strains. Among the highly cytotoxic compounds were sulfonylureas, which include 20 active ingredients. In addition, this class includes active pharmaceutical ingredients used for the manufacture of antidiabetics drugs. A traditional selection methodology was applied using the cultivation of S. typhimurium TA100 in the presence of high concentrations of thifensulfuronmethyl (TFSM) to obtain a resistant test strain insusceptible to sulfonylurea toxic effect. Two strains resistant not only to sulfonylureas (SFU) but also triazolepyrimidines were received. The first mutant strain (deposited as S. typhimurium VKPM B-14099 in the Russian National Collection of Industrial Microorganisms) demonstrated the TA100 phenotypic characteristics: hisG46, rfa, ΔuvrB-bio, pKM101. The second strain (deposited as S. typhimurium VKPM B-14359) showed the TA1535 phenotypic characteristics and probably lost the R-factor due to the selection using the poor Gm-media with TFSM. Positive controls caused pronounced mutagenic effects (±S9) in both strains, consequently the mutants did not lose the ability to respond to induction of the reverse gene mutations. The maximum non-cytotoxic concentrations of SFUs and triazole-pyrimidines for the Ames test strains did not exceed 0.05-0.125 mg/plate, while no evidence of cytotoxicity was observed for the mutants up to 5.0 mg/plate. Electron microscopy of the ultrathin sections of Salmonella cells grown with and without TFSM showed an obvious difference in the structure of the cell wall and cytoplasm in mutant and parental cultures. The concurrent resistance both to SFU and triazolepyrimidines was assumed to be mediated by the same mechanism of action of the pesticides from these classes - inhibition of acetohydroxyacid synthase. To confirm this hypothesis, the tests in the presence of branched-chain amino acids were carried out. The enrichment of agar with isoleucine prevented the toxic effects of SFU and triazolepyrimidines for all Ames test strains used in the study, while strong cytotoxicity was observed in the presence of valine and leucine. Considering the tolerance of strains both to SFU and triazolpyrimidines and the results with branched-chain amino acids, the modification of target acetohydroxyacid synthase was supposed the key to the acquired resistance. The new strains resistant to sulfonylureas and triazole-pyrimidines expands the possibilities to reveal mutagenic impurities that may occur in TGAIs in small amounts.

Cancer Patients' Preferences and Perceptions of Advantages and Disadvantages of Telehealth Visits During the COVID-19 Pandemic.

PURPOSE: We aimed to ascertain oncology patients' perceptions of telehealth versus in-person (IP) visits for different types of clinical encounters. METHODS: We surveyed adults undergoing cancer treatment at Kaiser Permanente Northern California infusion centers between November 2021 and May 2022 using a self-administered questionnaire. Patients were asked about visit modality preferences (video, phone, and IP) for six types of clinical discussions, overall advantages and disadvantages of telehealth (video or phone) versus IP modalities, and barriers to video visit use. RESULTS: The 839 patients who completed surveys in English were 63% female; median age 63 years; 64% White; and 73% college-educated (45% ≥bachelor's degree). For the first postdiagnosis discussion visit, 83% of patients preferred IP, followed by video (27%) and phone (18%). For follow-up visits, 52% of patients preferred IP, 50% video, and 37% phone. For discussions of bad news and sensitive topics, respectively, 68% and 62% preferred IP, 44% and 48% video, and 32% and 41% phone visits. Delivery of good news was acceptable through IP (49%), video (52%), or phone (49%) visits. Perceived advantages of IP visits were greater feelings of connection with their doctor (58%), confidence in physical examinations (73%), and ease in showing things (67%) and talking (51%) to the doctor. Advantages of telehealth visits included saved time (72%) and money (38%), less infection exposure (64%), less travel concerns (45%), and ability to include more people (28%). Of 24% of patients who felt video visits would be hard, 51% cited poor internet, 41% lack of an adequate device, and 28% difficulty signing on. CONCLUSION: Our results support continued use and reimbursement for telehealth visits with patients with cancer for most types of clinical encounters, including clinical trials.

Inhibition of anti-tumor immunity by melanoma cell-derived Activin-A depends on STING.

The transforming growth factor-ß (TGF-ß) family member activin A (hereafter Activin-A) is overexpressed in many cancer types, often correlating with cancer-associated cachexia and poor prognosis. Activin-A secretion by melanoma cells indirectly impedes CD8+ T cell-mediated anti-tumor immunity and promotes resistance to immunotherapies, even though Activin-A can be proinflammatory in other contexts. To identify underlying mechanisms, we here analyzed the effect of Activin-A on syngeneic grafts of Braf mutant YUMM3.3 mouse melanoma cells and on their microenvironment using single-cell RNA sequencing. We found that the Activin-A-induced immune evasion was accompanied by a proinflammatory interferon signature across multiple cell types, and that the associated increase in tumor growth depended at least in part on pernicious STING activity within the melanoma cells. Besides corroborating a role for proinflammatory signals in facilitating immune evasion, our results suggest that STING holds considerable potential as a therapeutic target to mitigate tumor-promoting Activin-A signaling at least in melanoma.

Advance Directives for Patients With Breast Cancer: Applying the Right Info/Right Care/Right Patient/Right Time Oncology Model.

Background Advance directives (AD) are an important component of life care planning for patients undergoing treatment for cancer; however, there are few effective interventions to increase AD rates. In this quality improvement project, the authors integrated AD counseling into a novel right info/right care/right patient/right time (4R) sequence of care oncology delivery intervention for breast cancer patients in an integrated health care delivery system. Methods The authors studied two groups of patients with newly diagnosed breast cancer who attended a multidisciplinary clinic and underwent definitive surgery at a single facility. The usual care (UC) cohort (N = 139) received care from October 1, 2019 to September 30, 2020. The 4R cohort (N = 141) received care from October 1, 2020 to September 30, 2121 that included discussing AD completion with a health educator prior to surgery. The authors used bivariate analyses to assess whether the AD intervention increased AD completion rates and to identify factors influencing AD completion. Results The UC and 4R cohorts were similar in age, gender, race/ethnicity, interpreter need, Elixhauser comorbidity index, National Comprehensive Cancer Network distress score ≥ 5, surgery type, stage, histology, grade, and Estrogen receptor/Progesterone receptor/ human epidermal growth factor receptor 2 (ER/PR/HER2) status. AD completion rates prior to surgery were significantly higher for the 4R vs UC cohort (73.8%, 95% confidence interval [CI] [66.5%-81.0%] vs 15.1%, 95% CI [9.2%-21.1%], p < .01) and did not significantly differ by age, race, need for interpreter, or distress scores. Conclusion Incorporation of a health educator discussion into a 4R care sequence plan significantly increased rates of time-sensitive AD completion.

Therapeutic Targeting of LIF Overcomes Macrophage-mediated Immunosuppression of the Local Tumor Microenvironment.

PURPOSE: Leukemia inhibitory factor (LIF) is a multifunctional cytokine with numerous reported roles in cancer and is thought to drive tumor development and progression. Characterization of LIF and clinical-stage LIF inhibitors would increase our understanding of LIF as a therapeutic target. EXPERIMENTAL DESIGN: We first tested the association of LIF expression with transcript signatures representing multiple processes regulating tumor development and progression. Next, we developed MSC-1, a high-affinity therapeutic antibody that potently inhibits LIF signaling and tested it in immune competent animal models of cancer. RESULTS: LIF was associated with signatures of tumor-associated macrophages (TAM) across 7,769 tumor samples spanning 22 solid tumor indications. In human tumors, LIF receptor was highly expressed within the macrophage compartment and LIF treatment drove macrophages to acquire immunosuppressive capacity. MSC-1 potently inhibited LIF signaling by binding an epitope that overlaps with the gp130 receptor binding site on LIF. MSC-1 showed monotherapy efficacy in vivo and drove TAMs to acquire antitumor and proinflammatory function in syngeneic colon cancer mouse models. Combining MSC-1 with anti-PD1 leads to strong antitumor response and a long-term tumor-free survival in a significant proportion of treated mice. CONCLUSIONS: Overall, our findings highlight LIF as a therapeutic target for cancer immunotherapy.

Microbial steroid transformations: current state and prospects.

Studies of steroid modifications catalyzed by microbial whole cells represent a well-established research area in white biotechnology. Still, advances over the last decade in genetic and metabolic engineering, whole-cell biocatalysis in non-conventional media, and process monitoring raised research in this field to a new level. This review summarizes the data on microbial steroid conversion obtained since 2003. The key reactions of structural steroid functionalization by microorganisms are highlighted including sterol side-chain degradation, hydroxylation at various positions of the steroid core, and redox reactions. We also describe methods for enhancement of bioprocess productivity, selectivity of target reactions, and application of microbial transformations for production of valuable pharmaceutical ingredients and precursors. Challenges and prospects of whole-cell biocatalysis applications in steroid industry are discussed.

Hinokiflavone Inhibits MDM2 Activity by Targeting the MDM2-MDMX RING Domain.

The proto-oncogene MDM2 is frequently amplified in many human cancers and its overexpression is clinically associated with a poor prognosis. The oncogenic activity of MDM2 is demonstrated by its negative regulation of tumor suppressor p53 and the substrate proteins involved in DNA repair, cell cycle control, and apoptosis pathways. Thus, inhibition of MDM2 activity has been pursued as an attractive direction for the development of anti-cancer therapeutics. Virtual screening was performed using the crystal structure of the MDM2-MDMX RING domain dimer against a natural product library and identified a biflavonoid Hinokiflavone as a promising candidate compound targeting MDM2. Hinokiflavone was shown to bind the MDM2-MDMX RING domain and inhibit MDM2-mediated ubiquitination in vitro. Hinokiflavone treatment resulted in the downregulation of MDM2 and MDMX and induction of apoptosis in various cancer cell lines. Hinokiflavone demonstrated p53-dependent and -independent tumor-suppressive activity. This report provides biochemical and cellular evidence demonstrating the anti-cancer effects of Hinokiflavone through targeting the MDM2-MDMX RING domain.

Activin-A impairs CD8 T cell-mediated immunity and immune checkpoint therapy response in melanoma.

BACKGROUND: Activin-A, a transforming growth factor ß family member, is secreted by many cancer types and is often associated with poor disease prognosis. Previous studies have shown that Activin-A expression can promote cancer progression and reduce the intratumoral frequency of cytotoxic T cells. However, the underlying mechanisms and the significance of Activin-A expression for cancer therapies are unclear. METHODS: We analyzed the expression of the Activin-A encoding gene INHBA in melanoma patients and the influence of its gain- or loss-of-function on the immune infiltration and growth of BRAF-driven YUMM3.3 and iBIP2 mouse melanoma grafts and in B16 models. Using antibody depletion strategies, we investigated the dependence of Activin-A tumor-promoting effect on different immune cells. Immune-regulatory effects of Activin-A were further characterized in vitro and by an adoptive transfer of T cells. Finally, we assessed INHBA expression in melanoma patients who received immune checkpoint therapy and tested whether it impairs the response in preclinical models. RESULTS: We show that Activin-A secretion by melanoma cells inhibits adaptive antitumor immunity irrespective of BRAF status by inhibiting CD8+ T cell infiltration indirectly and even independently of CD4 T cells, at least in part by attenuating the production of CXCL9/10 by myeloid cells. In addition, we show that Activin-A/INHBA expression correlates with anti-PD1 therapy resistance in melanoma patients and impairs the response to dual anti-cytotoxic T-Lymphocyte associated protein 4/anti-PD1 treatment in preclinical models. CONCLUSIONS: Our findings suggest that strategies interfering with Activin-A induced immune-regulation offer new therapeutic opportunities to overcome CD8 T cell exclusion and immunotherapy resistance.

Crystal structure and molecular modeling study of N-carbamoylsarcosine amidase Ta0454 from Thermoplasma acidophilum.

A crystal structure of the putative N-carbamoylsarcosine amidase (CSHase) Ta0454 from Thermoplasma acidophilum was solved by single-wavelength anomalous diffraction and refined at a resolution of 2.35A. CSHases are involved in the degradation of creatinine. Ta0454 shares a similar fold and a highly conserved C-D-K catalytic triad (Cys123, Asp9, and Lys90) with the structures of three cysteine hydrolases (PDB codes 1NBA, 1IM5, and 2H0R). Molecular dynamics (MD) simulations of Ta0454/N-carbamoylsarcosine and Ta0454/pyrazinamide complexes were performed to determine the structural basis of the substrate binding pattern for each ligand. Based on the MD-simulated trajectories, the MM/PBSA method predicts binding free energies of -24.5 and -17.1 kcal/mol for the two systems, respectively. The predicted binding free energies suggest that Ta0454 is selective for N-carbamoylsarcosine over pyrazinamide, and zinc ions play an important role in the favorable substrate bound states.