Finding the optimal access for proximal upper limb artery (PULA) interventions: Lessons learned from the PULA multicenter registry.

OBJECTIVE: The multicenter proximal upper limb artery (PULA) Registry was created to study the optimal puncture sites for the interventions involving the subclavian, axillary, and innominate arteries. BACKGROUND: Little is known about the optimal vascular access for PULA interventions, despite the well-known technical complexity of these procedures. METHODS: We performed the retrospective analysis of consecutive patients treated for symptomatic steno-occlusive disease of the proximal upper limb arteries between January 2015 and December 2019 in three high-volume centers. Acute thrombotic occlusions were excluded from the study. RESULTS: Two hundred and seventy-two patients were treated for significant stenosis and 108 for total occlusion. The baseline patient's characteristics were similar, except for the higher median age of the stenotic patients: 68.5 years (31.1; 90.0) versus 64 years (38.0; 86.0) p = 0.0015. Successful revascularization rate was higher in the stenotic group 93.75% (255/272) versus 86.11% (93/108) p = 0.0230, while the procedure length 27 min (8; 133) versus 46 min (7; 140) p = 0.0001 and fluoroscopy times 439 s (92; 2993) versus 864 s (86; 4176) p = 0.0001 were higher in the occlusion group. The main adverse event rate was similarly low. Dual access was used more often to treat occlusions (60.19% (65/108) vs. 11.40% (31/272) p = 0.0001) without significantly increasing the complication rate. The safest access was ultrasound-guided distal radial artery puncture, significantly better than conventional radial access with 0% (0/31) versus 13.6% (18/131) p = 0.0253 complication. CONCLUSIONS: The percutaneous revascularization of proximal upper limb arteries is a safe and effective. Dual access can be applied to increase treatment efficacy, without significantly compromising safety.

Adapted ATPase domain communication overcomes the cytotoxicity of p97 inhibitors.

The AAA+ ATPase p97 regulates ubiquitin-dependent protein homeostasis and has been pursued as a cancer drug target. The ATP-competitive inhibitor CB-5083 and allosteric inhibitor NMS-873 are the most advanced p97 inhibitors described to date. Previous studies have reported that their cytotoxicity can be readily overcome and involves single p97 mutations in the linker between the D1 and D2 ATPase domains and within D2. We report here that the proline 472 to leucine (P472L) mutation, in the D1-D2 linker and identified in CB-5083-resistant cells, desensitizes p97 to both inhibitor classes. This mutation does not disrupt the distinct D2-binding sites of the inhibitors. Instead, P472L changes ATPase domain communication within the p97 hexamer. P472L enhances cooperative D2 ATP binding and hydrolysis. This mechanism alters the function of the D1-D2 linker in the control of D2 activity involving the ATP-bound state of D1. Although increased D2 activity is sufficient to desensitize the P472L mutant to NMS-873, the mutant's desensitization to CB-5083 also requires D1 ATPase domain function. Our study highlights the remarkable adaptability of p97 ATPase domain communication that enables escape from mechanistically distinct classes of cytotoxic p97 inhibitors.

Short- and long-term results with a percutaneous treatment in critical hand ischaemia.

BACKGROUND: The aim of this prospective registry was to determine the feasibility, safety, and outcomes of percutaneous transluminal angioplasty and thrombolysis in the treatment of critical hand ischemia (CHI). METHODS: One-hundred one patients (aged 60.6 ± 15.3 years) were treated for CHI between 2012 and 2016 in three cardiovascular centers. Anatomically, the upper arm was divided into three segments (I-subclavian, II-brachial, and III-forearm). We examined the rates of technical and clinical success, major adverse events (MAEs), and vascular complications at 1 year and at long-term follow-up. RESULTS: Nineteen patients (18.8%) were treated for acute CHI, and 82 (81.2%) for chronic CHI. Median follow-up was 36.9 (19.6-68.3) months. Clinical symptoms were isolated rest pain in 91 patients (90.1%) and digital ulcer or gangrene in 10 patients (9.9%). The technical and clinical success rate of intervention was 96.0% (97/101) and 84.2% (85/101) at 1 year. Angioplasty was performed in Segments I, II, and III in 28 (27.7%), in 29 (28.7%), and 44 (43.5%) patients. Stent implantation was necessary in 47 patients (46.8%). Vascular access site complications were found in 2.1% of the sample. After 1 year, MAEs occurred in 27 patients (26.9%), and the target lesion revascularization rate was 11.9%. In two patients (1.9%), thoracic sympatectomy was necessary, and two patients (1.9%) underwent minor finger amputations. CONCLUSIONS: Angioplasty of hand vessels for CHI is a feasible and safe procedure with acceptable rates of technical success and hand healing. MAEs are frequent because the rate of severe comorbidities is high.

Re-evaluating the kinetics of ATP hydrolysis during initiation of DNA sliding by Type III restriction enzymes.

DNA cleavage by the Type III restriction enzymes requires long-range protein communication between recognition sites facilitated by thermally-driven 1D diffusion. This 'DNA sliding' is initiated by hydrolysis of multiple ATPs catalysed by a helicase-like domain. Two distinct ATPase phases were observed using short oligoduplex substrates; the rapid consumption of ∼10 ATPs coupled to a protein conformation switch followed by a slower phase, the duration of which was dictated by the rate of dissociation from the recognition site. Here, we show that the second ATPase phase is both variable and only observable when DNA ends are proximal to the recognition site. On DNA with sites more distant from the ends, a single ATPase phase coupled to the conformation switch was observed and subsequent site dissociation required little or no further ATP hydrolysis. The overall DNA dissociation kinetics (encompassing site release, DNA sliding and escape via a DNA end) were not influenced by the second phase. Although the data simplifies the ATP hydrolysis scheme for Type III restriction enzymes, questions remain as to why multiple ATPs are hydrolysed to prepare for DNA sliding.

Type III restriction endonucleases are heterotrimeric: comprising one helicase-nuclease subunit and a dimeric methyltransferase that binds only one specific DNA.

Fundamental aspects of the biochemistry of Type III restriction endonucleases remain unresolved despite being characterized by numerous research groups in the past decades. One such feature is the subunit stoichiometry of these hetero-oligomeric enzyme complexes, which has important implications for the reaction mechanism. In this study, we present a series of results obtained by native mass spectrometry and size exclusion chromatography with multi-angle light scattering consistent with a 1:2 ratio of Res to Mod subunits in the EcoP15I, EcoPI and PstII complexes as the main holoenzyme species and a 1:1 stoichiometry of specific DNA (sDNA) binding by EcoP15I and EcoPI. Our data are also consistent with a model where ATP hydrolysis activated by recognition site binding leads to release of the enzyme from the site, dissociation from the substrate via a free DNA end and cleavage of the DNA. These results are discussed critically in the light of the published literature, aiming to resolve controversies and discuss consequences in terms of the reaction mechanism.

Lys11- and Lys48-linked ubiquitin chains interact with p97 during endoplasmic-reticulum-associated degradation.

The ATPase associated with various cellular activities p97 has a critical function in the cytoplasmic degradation of proteins misfolded in the ER (endoplasmic reticulum) through a mechanism known as ERAD (ER-associated degradation). During this process, p97 binds polyubiquitinated ERAD substrates and couples ATP hydrolysis to their dislocation from the ER as a prerequisite to destruction by the proteasome. The ubiquitin signals important for this process are not fully understood. In the present paper we report that p97 interacts with Lys11- and Lys48-linked ubiquitin polymers, but not those containing Lys63 linkages. Disruption of p97 through siRNA-mediated depletion, dominant-negative overexpression or chemical inhibition results in the accumulation of Lys11 and Lys48 ubiquitin chains predominantly at the ER membrane, and is associated with ER stress induction. We show that a catalytically inactive deubiquitinating enzyme and p97 cofactor YOD1 enhances the accumulation of Lys11- and Lys48-linked polyubiquitin in the cytoplasm, at the ER membrane and bound to p97. In addition to general effects on p97-associated ubiquitin polymers, the ERAD substrate CD3δ is modified with both Lys11 and Lys48 ubiquitin chains prior to p97-dependent dislocation. Collectively, the results of the present study are consistent with a major role for p97 in the recognition of Lys11 and Lys48 polyubiquitinated proteins before their degradation by the proteasome.

The cyclomodulin cycle inhibiting factor (CIF) alters cullin neddylation dynamics.

The bacterial effector protein cycle inhibiting factor (CIF) converts glutamine 40 of NEDD8 to glutamate (Q40E), causing cytopathic effects and inhibiting cell proliferation. Although these have been attributed to blocking the functions of cullin-RING ubiquitin ligases, how CIF modulates NEDD8-dependent signaling is unclear. Here we use conditional NEDD8-dependent yeast to explore the effects of CIF on cullin neddylation. Although CIF causes cullin deneddylation and the generation of free NEDD8 Q40E, inhibiting the COP9 signalosome (CSN) allows Q40E to form only on NEDD8 attached to cullins. In the presence of the CSN, NEDD8 Q40E is removed from cullins more rapidly than NEDD8, leading to a decrease in steady-state cullin neddylation. As NEDD8 Q40E is competent for cullin conjugation in the absence of functional CSN and with overexpression of the NEDD8 ligase Dcn1, our data are consistent with NEDD8 deamidation causing enhanced deneddylation of cullins by the CSN. This leads to a dramatic change in the extent of activated cullin-RING ubiquitin ligases.

Dissociation from DNA of Type III Restriction-Modification enzymes during helicase-dependent motion and following endonuclease activity.

DNA cleavage by the Type III Restriction-Modification (RM) enzymes requires the binding of a pair of RM enzymes at two distant, inversely orientated recognition sequences followed by helicase-catalysed ATP hydrolysis and long-range communication. Here we addressed the dissociation from DNA of these enzymes at two stages: during long-range communication and following DNA cleavage. First, we demonstrated that a communicating species can be trapped in a DNA domain without a recognition site, with a non-specific DNA association lifetime of ∼ 200 s. If free DNA ends were present the lifetime became too short to measure, confirming that ends accelerate dissociation. Secondly, we observed that Type III RM enzymes can dissociate upon DNA cleavage and go on to cleave further DNA molecules (they can 'turnover', albeit inefficiently). The relationship between the observed cleavage rate and enzyme concentration indicated independent binding of each site and a requirement for simultaneous interaction of at least two enzymes per DNA to achieve cleavage. In light of various mechanisms for helicase-driven motion on DNA, we suggest these results are most consistent with a thermally driven random 1D search model (i.e. 'DNA sliding').

Discovery of Monovalent Direct Degraders of BRD4 That Act Via the Recruitment of DCAF11.

Targeted protein degradation (TPD) using the ubiquitin proteasome system (UPS) is a rapidly growing drug discovery modality to eliminate pathogenic proteins. Strategies for TPD have focused on heterobifunctional degraders that often suffer from poor drug-like properties, and molecular glues that rely on serendipitous discovery. Monovalent "direct" degraders represent an alternative approach, in which small molecules bind to a target protein and induce degradation of that protein through the recruitment of an E3 ligase complex. Using an ultra-high throughput cell-based screening platform, degraders of the bromodomain extra-terminal (BET) protein BRD4 were identified and optimized to yield a lead compound, PLX-3618. In this paper, we demonstrate that PLX-3618 elicited UPS-mediated selective degradation of BRD4, resulting in potent anti-tumor activity in vitro and in vivo. Characterization of the degradation mechanism identified DCAF11 as the E3 ligase required for PLX-3618-mediated degradation of BRD4. Protein-protein interaction studies verified a BRD4:PLX-3618:DCAF11 ternary complex, and mutational studies provided further insights into the DCAF11-mediated degradation mechanism. Collectively, these results demonstrate the discovery and characterization of a novel small molecule that selectively degrades BRD4 through the recruitment of the E3 substrate receptor, DCAF11, and promotes potent anti-tumor activity in vivo.

Discovery of Monovalent Direct Degraders of BRD4 that Act via the Recruitment of DCAF11.

Targeted protein degradation (TPD) using the ubiquitin proteasome system (UPS) is a rapidly growing drug discovery modality to eliminate pathogenic proteins. Strategies for TPD have focused on heterobifunctional degraders that often suffer from poor drug-like properties, and molecular glues that rely on serendipitous discovery. Monovalent "direct" degraders represent an alternative approach, in which small molecules bind to a target protein and induce degradation of that protein through the recruitment of an E3 ligase complex. Using an ultra-high throughput cell-based screening platform, degraders of the bromodomain extraterminal protein BRD4 were identified and optimized to yield a lead compound, PLX-3618. In this paper, we demonstrate that PLX-3618 elicited UPS-mediated selective degradation of BRD4, resulting in potent antitumor activity in vitro and in vivo. Characterization of the degradation mechanism identified DCAF11 as the E3 ligase required for PLX-3618-mediated degradation of BRD4. Protein-protein interaction studies verified a BRD4:PLX-3618:DCAF11 ternary complex, and mutational studies provided further insights into the DCAF11-mediated degradation mechanism. Collectively, these results demonstrate the discovery and characterization of a novel small molecule that selectively degrades BRD4 through the recruitment of the E3 substrate receptor, DCAF11, and promotes potent antitumor activity in vivo.

DNA cleavage site selection by Type III restriction enzymes provides evidence for head-on protein collisions following 1D bidirectional motion.

DNA cleavage by the Type III Restriction-Modification enzymes requires communication in 1D between two distant indirectly-repeated recognitions sites, yet results in non-specific dsDNA cleavage close to only one of the two sites. To test a recently proposed ATP-triggered DNA sliding model, we addressed why one site is selected over another during cleavage. We examined the relative cleavage of a pair of identical sites on DNA substrates with different distances to a free or protein blocked end, and on a DNA substrate using different relative concentrations of protein. Under these conditions a bias can be induced in the cleavage of one site over the other. Monte-Carlo simulations based on the sliding model reproduce the experimentally observed behaviour. This suggests that cleavage site selection simply reflects the dynamics of the preceding stochastic enzyme events that are consistent with bidirectional motion in 1D and DNA cleavage following head-on protein collision.

Type III restriction enzymes cleave DNA by long-range interaction between sites in both head-to-head and tail-to-tail inverted repeat.

Cleavage of viral DNA by the bacterial Type III Restriction-Modification enzymes requires the ATP-dependent long-range communication between a distant pair of DNA recognition sequences. The classical view is that Type III endonuclease activity is only activated by a pair of asymmetric sites in a specific head-to-head inverted repeat. Based on this assumption and due to the presence of helicase domains in Type III enzymes, various motor-driven DNA translocation models for communication have been suggested. Using both single-molecule and ensemble assays we demonstrate that Type III enzymes can also cleave DNA with sites in tail-to-tail repeat with high efficiency. The ability to distinguish both inverted repeat substrates from direct repeat substrates in a manner independent of DNA topology or accessory proteins can only be reconciled with an alternative sliding mode of communication.

Abnormal development of the cerebral cortex and cerebellum in the setting of lamin B2 deficiency.

Nuclear lamins are components of the nuclear lamina, a structural scaffolding for the cell nucleus. Defects in lamins A and C cause an array of human diseases, including muscular dystrophy, lipodystrophy, and progeria, but no diseases have been linked to the loss of lamins B1 or B2. To explore the functional relevance of lamin B2, we generated lamin B2-deficient mice and found that they have severe brain abnormalities resembling lissencephaly, with abnormal layering of neurons in the cerebral cortex and cerebellum. This neuronal layering abnormality is due to defective neuronal migration, a process that is dependent on the organized movement of the nucleus within the cell. These studies establish an essential function for lamin B2 in neuronal migration and brain development.

Bifunctional apoptosis regulator (BAR), an endoplasmic reticulum (ER)-associated E3 ubiquitin ligase, modulates BI-1 protein stability and function in ER Stress.

Accumulation of misfolded proteins in the endoplasmic reticulum (ER) causes ER stress and activates inositol-requiring protein-1 (IRE1), among other ER-associated signaling proteins of the unfolded protein response (UPR) in mammalian cells. IRE1 signaling becomes attenuated under prolonged ER stress. The mechanisms by which this occurs are not well understood. An ER resident protein, Bax inhibitor-1 (BI-1), interacts with IRE1 and directly inhibits IRE1 activity. However, little is known about regulation of the BI-1 protein. We show here that bifunctional apoptosis regulator (BAR) functions as an ER-associated RING-type E3 ligase, interacts with BI-1, and promotes proteasomal degradation of BI-1. Overexpression of BAR reduced BI-1 protein levels in a RING-dependent manner. Conversely, knockdown of endogenous BAR increased BI-1 protein levels and enhanced inhibition of IRE1 signaling during ER stress. We also found that the levels of endogenous BAR were reduced under prolonged ER stress. Our findings suggest that post-translational regulation of the BI-1 protein by E3 ligase BAR contributes to the dynamic control of IRE1 signaling during ER stress.

Engineering novel complement activity into a pulmonary surfactant protein.

Complement neutralizes invading pathogens, stimulates inflammatory and adaptive immune responses, and targets non- or altered-self structures for clearance. In the classical and lectin activation pathways, it is initiated when complexes composed of separate recognition and activation subcomponents bind to a pathogen surface. Despite its apparent complexity, recognition-mediated activation has evolved independently in three separate protein families, C1q, mannose-binding lectins (MBLs), and serum ficolins. Although unrelated, all have bouquet-like architectures and associate with complement-specific serine proteases: MBLs and ficolins with MBL-associated serine protease-2 (MASP-2) and C1q with C1r and C1s. To examine the structural requirements for complement activation, we have created a number of novel recombinant rat MBLs in which the position and orientation of the MASP-binding sites have been changed. We have also engineered MASP binding into a pulmonary surfactant protein (SP-A), which has the same domain structure and architecture as MBL but lacks any intrinsic complement activity. The data reveal that complement activity is remarkably tolerant to changes in the size and orientation of the collagenous stalks of MBL, implying considerable rotational and conformational flexibility in unbound MBL. Furthermore, novel complement activity is introduced concurrently with MASP binding in SP-A but is uncontrolled and occurs even in the absence of a carbohydrate target. Thus, the active rather than the zymogen state is default in lectin.MASP complexes and must be inhibited through additional regions in circulating MBLs until triggered by pathogen recognition.

REDD1, an inhibitor of mTOR signalling, is regulated by the CUL4A-DDB1 ubiquitin ligase.

The cellular response to hypoxia involves several signalling pathways that mediate adaptation and survival. REDD1 (regulated in development and DNA damage responses 1), a hypoxia-inducible factor-1 target gene, has a crucial role in inhibiting mammalian target of rapamycin complex 1 (mTORC1) signalling during hypoxic stress. However, little is known about the signalling pathways and post-translational modifications that regulate REDD1 function. Here, we show that REDD1 is subject to ubiquitin-mediated degradation mediated by the CUL4A-DDB1-ROC1-beta-TRCP E3 ligase complex and through the activity of glycogen synthase kinase 3beta. Furthermore, REDD1 degradation is crucially required for the restoration of mTOR signalling as cells recover from hypoxic stress. Our findings define a mechanism underlying REDD1 degradation and its importance for regulating mTOR signalling.

Analogous interactions in initiating complexes of the classical and lectin pathways of complement.

The classical and lectin pathways of complement activation neutralize pathogens and stimulate key immunological processes. Both pathways are initiated by collagen-containing, soluble pattern recognition molecules associated with specific serine proteases. In the classical pathway, C1q binds to Ab-Ag complexes or bacterial surfaces to activate C1r and C1s. In the lectin pathway, mannan-binding lectin and ficolins bind to carbohydrates on pathogens to activate mannan-binding lectin-associated serine protease 2. To characterize the interactions leading to classical pathway activation, we have analyzed binding between human C1q, C1r, and C1s, which associate to form C1, using full-length and truncated protease components. We show that C1r and C1s bind to C1q independently. The CUB1-epidermal growth factor fragments contribute most toward binding, but CUB2 of C1r, but not of C1s, is also important. Each C1rs tetramer presents a total of six binding sites, one for each of the collagenous domains of C1q. We also demonstrate that subcomponents of the lectin and classical pathways cross-interact. Thus, although the stoichiometries of complexes differ, interactions are analogous, with equivalent contacts between recognition and protease subcomponents. Importantly, these new data are contrary to existing models of C1 and enable us to propose a new model using mannan-binding lectin-mannan-binding lectin-associated serine protease interactions as a template.

Distal Radial Artery Access for Coronary and Peripheral Procedures: A Multicenter Experience.

INTRODUCTION: Distal radial access (dRA) has recently gained global popularity as an alternative access route for vascular procedures. Among the benefits of dRA are the low risk of entry site bleeding complications, the low rate of radial artery occlusion, and improved patient and operator comfort. The aim of this large multicenter registry was to demonstrate the feasibility and safety of dRA in a wide variety of routine procedures in the catheterization laboratory, ranging from coronary angiography and percutaneous coronary intervention to peripheral procedures. METHODS: The study comprised 1240 patients who underwent coronary angiography, PCI or noncoronary procedures through dRA in two Hungarian centers from January 2019 to April 2021. Baseline patient characteristics, number and duration of arterial punctures, procedural success rate, crossover rate, postoperative compression time, complications, hospitalization duration, and different learning curves were analyzed. RESULTS: The average patient age was 66.4 years, with 66.8% of patients being male. The majority of patients (74.04%) underwent a coronary procedure, whereas 25.96% were involved in noncoronary interventions. dRA was successfully punctured in 97% of all patients, in all cases with ultrasound guidance. Access site crossover was performed in 2.58% of the patients, mainly via the contralateral dRA. After experiencing 150 cases, the dRA success rate plateaued at >96%. Our dedicated dRA step-by step protocol resulted in high open radial artery (RA) rates: distal and proximal RA pulses were palpable in 99.68% of all patients at hospital discharge. The rate of minor vascular complications was low (1.5%). A threshold of 50 cases was sufficient for already skilled radial operators to establish a reliable procedural method of dRA access. CONCLUSION: The implementation of distal radial artery access in the everyday routine of a catheterization laboratory for coronary and noncoronary interventions is feasible and safe with an acceptable learning curve.

Site directed mutagenesis at position 193 of human trypsin 4 alters the rate of conformational change during activation: role of local internal viscosity in protein dynamics.

Upon activation of trypsinogen four peptide segments flanked by hinge glycine residues undergo conformational changes. To test whether the degree of conformational freedom of hinge regions affects the rate of activation, we introduced amino acid side chains of different characters at one of the hinges (position 193) and studied their effects on the rate constant of the conformational change. This structural rearrangement leading to activation was triggered by a pH-jump and monitored by intrinsic fluorescence change in the stopped-flow apparatus. We found that an increase in the size of the side chain at position 193 is associated with the decrease of the reaction rate constant. To analyze the thermodynamics of the reaction, temperature dependence of the reaction rate constants was examined in a wide temperature range (5-60 degrees C) using a novel temperature-jump/stopped-flow apparatus developed in our laboratory. Our data show that the mutations do not affect the activation energy (the exponential term) of the reaction, but they significantly alter the preexponential term of the Arrhenius equation. The effect of solvent viscosity on the rate constants of the conformational change during activation of the wild type enzyme and its R193G and R193A mutants was determined and evaluated on the basis of Kramers' theory. Based on this we propose that the reaction rate of this conformational transition is regulated by the internal molecular friction, which can be specifically modulated by mutagenesis in the hinge region.

Visible light induces matrix metalloproteinase-9 expression in rat eye.

Up-regulation of matrix metalloproteinase-9 (MMP-9, gelatinase B) in the nervous system has been demonstrated when excitotoxicity-induced tissue remodeling and neuronal death occurs. Induction of MMP-9 by a natural stimulus has not been observed yet. Using RT-PCR and gelatin-zymography we demonstrated MMP-9 induction at transcriptional and protein levels in different structures of the rat eye following over-stimulation with white light. MMP-9 elevation occurred in the retina without reduction in photoreceptor number or major anatomical reorganization. A transient decrease in electroretinogram b-wave indicated the functional recovery. Retrobulbar injection of a broad-spectrum MMP-inhibitor GM6001, slowed the recovery rate of b-wave amplitude. Even room-light applied to dark-adapted awake animals induced MMP-9 increase in the retina, which suggests a role for MMP-9 in physiological functional plasticity of the nervous system, such as light adaptation. This is the first demonstration of MMP-9 induction by a sensory stimulus.