Hck/Fgr Kinase Deficiency Reduces Plaque Growth and Stability by Blunting Monocyte Recruitment and Intraplaque Motility

BACKGROUND

Leukocyte migration is critical for the infiltration of monocytes and accumulation of monocyte-derived macrophages in inflammation. Considering that Hck and Fgr are instrumental in this process, their impact on atherosclerosis and on lesion inflammation and stability was evaluated.

METHODS AND RESULTS

Hematopoietic Hck/Fgr-deficient, LDLr(-/-) chimeras, obtained by bone marrow transplantation, had smaller but, paradoxically, less stable lesions with reduced macrophage content, overt cap thinning, and necrotic core expansion as the most prominent features. Despite a Ly6C(high)-skewed proinflammatory monocyte phenotype, Hck/Fgr deficiency led to disrupted adhesion of myeloid cells to and transmigration across endothelial monolayers in vitro and atherosclerotic plaques in vivo, as assessed by intravital microscopy, flow cytometry, and histological examination of atherosclerotic arteries. Moreover, Hck/Fgr-deficient macrophages showed blunted podosome formation and mesenchymal migration capacity. In consequence, transmigrated double-knockout macrophages were seen to accumulate in the fibrous cap, potentially promoting its focal erosion, as observed for double-knockout chimeras.

CONCLUSIONS

The hematopoietic deficiency of Hck and Fgr led to attenuated atherosclerotic plaque formation by abrogating endothelial adhesion and transmigration; paradoxically, it also promoted plaque instability by causing monocyte subset imbalance and subendothelial accumulation, raising a note of caution regarding src kinase-targeted intervention in plaque inflammation.

Molecular Mechanisms of Intrinsic Streptomycin Resistance in Mycobacterium abscessus

Streptomycin, the first drug used for the treatment of tuberculosis, shows limited activity against the highly resistant pathogen Mycobacterium abscessus We recently identified two aminoglycoside-acetylating genes [aac(2') and eis2] which, however, do not affect susceptibility to streptomycin. This suggests the existence of a discrete mechanism of streptomycin resistance. M. abscessus BLASTP analysis identified MAB_2385 as a close homologue of the 3″-O-phosphotransferase [APH(3″)] from the opportunistic pathogen Mycobacterium fortuitum as a putative streptomycin resistance determinant. Heterologous expression of MAB_2385 in Mycobacterium smegmatis increased the streptomycin MIC, while the gene deletion mutant M. abscessus ΔMAB_2385 showed increased streptomycin susceptibility. The MICs of other aminoglycosides were not altered in M. abscessus ΔMAB_2385. This demonstrates that MAB_2385 encodes a specific and prime innate streptomycin resistance determinant in M. abscessus We further explored the feasibility of applying rpsL-based streptomycin counterselection to generate gene deletion mutants in M. abscessus Spontaneous streptomycin-resistant mutants of M. abscessus ΔMAB_2385 were selected, and we demonstrated that the wild-type rpsL is dominant over the mutated rpsLK43R in merodiploid strains. In a proof of concept study, we exploited this phenotype for construction of a targeted deletion mutant, thereby establishing an rpsL-based counterselection method in M. abscessus.

Systems Biology Understanding of the Effects of Lithium on Cancer

Lithium has many widely varying biochemical and phenomenological effects, suggesting that a systems biology approach is required to understand its action. Multiple lines of evidence point to lithium as a significant factor in development of cancer, showing that understanding lithium action is of high importance. In this paper we undertake first steps toward a systems approach by analyzing mutual enrichment between the interactomes of lithium-sensitive enzymes and the pathways associated with cancer. This work integrates information from two important databases, STRING, and KEGG pathways. We find that for the majority of cancer pathways the mutual enrichment is statistically highly significant, reinforcing previous lines of evidence that lithium is an important influence on cancer.

Structure and biochemical characterization of an adenylate kinase originating from the psychrophilic organism Marinibacillus marinus

Adenylate kinases (AKs; EC 2.7.4.3) are essential members of the NMP kinase family that maintain cellular homeostasis by the interconversion of AMP, ADP and ATP. AKs play a critical role in adenylate homeostasis across all domains of life and have been used extensively as prototypes for the study of protein adaptation and the relationship of protein dynamics and stability to function. To date, kinetic studies of psychrophilic AKs have not been performed. In order to broaden understanding of extremophilic adaptation, the kinetic parameters of adenylate kinase from the psychrophile Marinibacillus marinus were examined and the crystal structure of this cold-adapted enzyme was determined at 2.0 A resolution. As expected, the overall structure and topology of the psychrophilic M. marinus AK are similar to those of mesophilic and thermophilic AKs. The thermal denaturation midpoint of M. marinus AK (321.1 K) is much closer to that of the mesophile Bacillus subtilis (320.7 K) than the more closely related psychrophile B. globisporus (316.4 K). In addition, the enzymatic properties of M. marinus AK are quite close to those of the mesophilic AK and suggests that M. marinus experiences temperature ranges in which excellent enzyme function over a broad temperature range (293-313 K) has been retained for the success of the organism. Even transient loss of AK function is lethal and as a consequence AK must be robust and be well adapted to the environment of the host organism.

Structure of Deinococcus radiodurans tunicamycin-resistance protein (TmrD), a phosphotransferase

The open-reading frame (ORF) DR_1419 in the Deinococcus radiodurans genome is annotated as a representative of the wide family of tunicamycin-resistance proteins as identified in a range of bacterial genomes. The D. radiodurans ORF DR_1419 was cloned and expressed; the protein TmrD was crystallized and its X-ray crystal structure was determined to 1.95 A resolution. The structure was determined using single-wavelength anomalous diffraction with selenomethionine-derivatized protein. The refined structure is the first to be reported for a member of the tunicamycin-resistance family. It reveals strong structural similarity to the family of nucleoside monophosphate kinases and to the chloramphenicol phosphotransferase of Streptomyces venezuelae, suggesting that the mode of action is possibly by phosphorylation of tunicamycin.

Key advances in biocatalytic phosphorylations in the last two decades: Biocatalytic syntheses in vitro and biotransformations in vivo (in humans)

Biocatalytic phosphorylation reactions provide several benefits, such as more direct, milder, more selective, and shorter access routes to phosphorylated products. Favorable characteristics of biocatalytic methodologies represent advantages for in vitro as well as for in vivo phosphorylation reactions, leading to important advances in the science of synthesis towards bioactive phosphorylated compounds in various areas. The scope of this review covers key advances of biocatalytic phosphorylation reactions over the last two decades, for biocatalytic syntheses in vitro and for biotransformations in vivo (in humans). From the origins of probiotic life to in vitro synthetic applications and in vivo formation of bioactive pharmaceuticals, the common purpose is to outline the importance, relevance, and underlying connections of biocatalytic phosphorylations of small molecules. Asymmetric phosphorylations attracting increased attention are highlighted. Phosphohydrolases, phosphotransferases, phosphorylases, phosphomutases, and other enzymes involved in phosphorus chemistry provide powerful toolboxes for resource-efficient and selective in vitro biocatalytic syntheses of phosphorylated metabolites, chiral building blocks, pharmaceuticals as well as in vivo enzymatic formation of biologically active forms of pharmaceuticals. Nature's large diversity of phosphoryl-group-transferring enzymes, advanced enzyme and reaction engineering toolboxes make biocatalytic asymmetric phosphorylations using enzymes a powerful and privileged phosphorylation methodology.

Merestinib monotherapy or in combination for japanese patients with advanced and/or metastatic cancer: A phase 1 study

This phase 1, multi‐center, nonrandomized, open‐label, dose‐escalation study consisted of Part A wherein merestinib 80 or 120 mg (40‐mg tablets) was administered orally QD during a 28‐day cycle to patients diagnosed with solid tumors and Part B wherein merestinib 80 mg (40‐mg tablets) was administered orally QD, and cisplatin 25 mg/m² + gemcitabine 1000 mg/m² administered IV on Day 1 and Day 8 of a 21‐day cycle (for a maximum of eight cycles) to patients diagnosed with biliary tract carcinoma (BTC). Nineteen patients were screened and 18 patients were (Part A, n = 10; Part B, n = 8) enrolled in the trial and received treatment. All patients in Parts A and B were from Japan and were within an age range of 43–73 years, with an ECOG PS of 0.1. No dose‐limiting toxicity or deaths were experienced in the study. Dose‐limiting toxicity equivalent toxicity of Grade 4 platelet count decreased (n = 1) and was observed in Part B. In Part A, treatment‐related Grade ≥3 TEAEs were reported in one patient (PT: ALT increased and AST increased), while in Part B, five patients reported treatment‐related Grade ≥3 TEAEs with four of the five patients reporting an event of neutrophil count decreased. No complete response was reported in either Part. One patient in Part B reported partial response while four patients in each part reported stable disease. Merestinib monotherapy was concluded to be tolerable in Japanese patients, and its combination with cisplatin and gemcitabine is a tolerable regimen for Japanese patients with BTC.

Trial registration: NCT03027284 (ClinicalTrials.gov) registered on 23 January 2017.

Structural basis for the diversity of the mechanism of nucleotide hydrolysis by the aminoglycoside-2''-phosphotransferases

Aminoglycoside phosphotransferases (APHs) are one of three families of aminoglycoside-modifying enzymes that confer high-level resistance to the aminoglycoside antibiotics via enzymatic modification. This has now rendered many clinically important drugs almost obsolete. The APHs specifically phosphorylate hydroxyl groups on the aminoglycosides using a nucleotide triphosphate as the phosphate donor. The APH(2'') family comprises four distinct members, isolated primarily from Enterococcus sp., which vary in their substrate specificities and also in their preference for the phosphate donor (ATP or GTP). The structure of the ternary complex of APH(2'')-IIIa with GDP and kanamycin was solved at 1.34 Å resolution and was compared with substrate-bound structures of APH(2'')-Ia, APH(2'')-IIa and APH(2'')-IVa. In contrast to the case for APH(2'')-Ia, where it was proposed that the enzyme-mediated hydrolysis of GTP is regulated by conformational changes in its N-terminal domain upon GTP binding, APH(2'')-IIa, APH(2'')-IIIa and APH(2'')-IVa show no such regulatory mechanism, primarily owing to structural differences in the N-terminal domains of these enzymes.

Investigating the Protective Effects of a Citrus Flavonoid on the Retardation Morphogenesis of the Oligodendroglia-like Cell Line by Rnd2 Knockdown

Recent discoveries suggest links between abnormalities in cell morphogenesis in the brain and the functional deficiency of molecules controlling signal transduction in glial cells such as oligodendroglia. Rnd2 is one such molecule and one of the Rho family monomeric GTP-binding proteins. Despite the currently known functions of Rnd2, its precise roles as it relates to cell morphogenesis and disease state remain to be elucidated. First, we showed that signaling through the loss of function of the rnd2 gene affected the regulation of oligodendroglial cell-like morphological differentiation using the FBD-102b cell line, which is often utilized as a differentiation model. The knockdown of Rnd2 using the clustered regularly interspaced palindromic repeats (CRISPR)/CasRx system or RNA interference was shown to slow morphological differentiation. Second, the knockdown of Prag1 or Fyn kinase, a signaling molecule acting downstream of Rnd2, slowed differentiation. Rnd2 or Prag1 knockdown also decreased Fyn phosphorylation, which is critical for its activation and for oligodendroglial cell differentiation and myelination. Of note, hesperetin, a citrus flavonoid with protective effects on oligodendroglial cells and neurons, can recover differentiation states induced by the knockdown of Rnd2/Prag1/Fyn. Here, we showed that signaling through Rnd2/Prag1/Fyn is involved in the regulation of oligodendroglial cell-like morphological differentiation. The effects of knocking down the signaling cascade molecule can be recovered by hesperetin, highlighting an important molecular structure involved in morphological differentiation.