Continuous nerve block versus thoracic epidural analgesia for post-operative pain of pectus excavatum repair: a systematic review and meta-analysis.

Surgery to repair pectus excavatum (PE) is often associated with severe postoperative pain, which can impact the length of hospital stay (LOS). While thoracic epidural analgesia (TEA) has traditionally been used for pain management in PE, its placement can sometimes result in severe neurological complications. Recently, paravertebral block (PVB) and erector spinae plane block (ESPB) have been recommended for many other chest and abdominal surgeries. However, due to the more severe and prolonged pain associated with PE repair, it is still unclear whether continuous administration of these blocks is as effective as TEA. Therefore, we conducted this systematic review and meta-analysis to demonstrate the equivalence of continuous PVB and ESPB to TEA.

Differential effects of SUMO1 and SUMO2 on circadian protein PER2 stability and function.

Posttranslational modification (PTM) of core circadian clock proteins, including Period2 (PER2), is required for proper circadian regulation. PER2 function is regulated by casein kinase 1 (CK1)-mediated phosphorylation and ubiquitination but little is known about other PER2 PTMs or their interaction with PER2 phosphorylation. We found that PER2 can be SUMOylated by both SUMO1 and SUMO2; however, SUMO1 versus SUMO2 conjugation had different effects on PER2 turnover and transcriptional suppressor function. SUMO2 conjugation facilitated PER2 interaction with ß-TrCP leading to PER2 proteasomal degradation. In contrast, SUMO1 conjugation, mediated by E3 SUMO-protein ligase RanBP2, enhanced CK1-mediated PER2S662 phosphorylation, inhibited PER2 degradation and increased PER2 transcriptional suppressor function. PER2 K736 was critical for both SUMO1- and SUMO2-conjugation. A PER2K736R mutation was sufficient to alter PER2 protein oscillation and reduce PER2-mediated transcriptional suppression. Together, our data revealed that SUMO1 versus SUMO2 conjugation acts as a determinant of PER2 stability and function and thereby affects the circadian regulatory system and the expression of clock-controlled genes.

Submental Ultrasound Is Effective in Predicting Difficult Mask Ventilation but Not in Difficult Laryngoscopy.

The goal of this study was to determine the utility of submental ultrasound parameters in distinguishing difficult airway management from easy airway management. Forty-one adult patients who underwent elective surgery under general anesthesia with endotracheal intubation from March to December 2018 were included. We used submental ultrasound to measure tongue base thickness (TBT) in the midsagittal plane and the distance between lingual arteries (DLA) in the transverse dimension. The primary outcome was difficult laryngoscopy, and the secondary outcome was difficult mask ventilation. Receiver operating characteristic curve analysis and logistic regression revealed no correlation between difficult laryngoscopy and SMUS measurements. Nevertheless, patients with difficult mask ventilation had significantly higher TBT (p = 0.009) and longer DLA (p = 0.010). After adjustment of confounding factors, increased TBT (>69.6 mm) was the sole independent predictor of difficult mask ventilation. The results indicated that SMUS is effective in predicting difficult mask ventilation but not difficult laryngoscopy.

Redox sensor NPGPx restrains ZAP70 activity and modulates T cell homeostasis.

Emerging evidences implicate the contribution of ROS to T cell activation and signaling. The tyrosine kinase, ζ-chain-associated protein of 70 kDa (ZAP70), is essential for T cell development and activation. However, it remains elusive whether a direct redox regulation affects ZAP70 activity upon TCR stimulation. Here, we show that deficiency of non-selenocysteine containing phospholipid hydroperoxide glutathione peroxidase (NPGPx), a redox sensor, results in T cell hyperproliferation and elevated cytokine productions. T cell-specific NPGPx-knockout mice reveal enhanced T-dependent humoral responses and are susceptible to experimental autoimmune encephalomyelitis (EAE). Through proteomic approaches, ZAP70 is identified as the key interacting protein of NPGPx through disulfide bonding. NPGPx is activated by ROS generated from TCR stimulation, and modulates ZAP70 activity through redox switching to reduce ZAP70 recruitment to TCR/CD3 complex in membrane lipid raft, therefore subduing TCR responses. These results reveal a delicate redox mechanism that NPGPx serves as a modulator to curb ZAP70 functions in maintaining T cell homeostasis.

NPGPx-Mediated Adaptation to Oxidative Stress Protects Motor Neurons from Degeneration in Aging by Directly Modulating O-GlcNAcase.

Amyotrophic lateral sclerosis (ALS), the most common motor neuron disease, usually occurs in middle-aged people. However, the molecular basis of age-related cumulative stress in ALS pathogenesis remains elusive. Here, we found that mice deficient in NPGPx (GPx7), an oxidative stress sensor, develop ALS-like phenotypes, including paralysis, muscle denervation, and motor neurons loss. Unlike normal spinal motor neurons that exhibit elevated O-GlcNAcylation against age-dependent oxidative stress, NPGPx-deficient spinal motor neurons fail to boost O-GlcNAcylation and exacerbate ROS accumulation, leading to cell death. Mechanistically, stress-activated NPGPx inhibits O-GlcNAcase (OGA) through disulfide bonding to fine-tune global O-GlcNAcylation. Pharmacological inhibition of OGA rescues spinal motor neuron loss in aged NPGPx-deficient mice. Furthermore, expression of NPGPx in ALS patients is significantly lower than in unaffected adults. These results suggest that NPGPx modulates O-GlcNAcylation by inhibiting OGA to cope with age-dependent oxidative stress and protect motor neurons from degeneration, providing a potential therapeutic axis for ALS.

Author Correction: Molecular mechanism of K65 acetylation-induced attenuation of Ubc9 and the NDSM interaction.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Molecular mechanism of K65 acetylation-induced attenuation of Ubc9 and the NDSM interaction.

The negatively charged amino acid-dependent sumoylation motif (NDSM) carries an additional stretch of acidic residues downstream of the consensus Ψ-K-x-E/D sumoylation motif. We have previously shown that acetylation of the SUMO E2 conjugase enzyme, Ubc9, at K65 downregulates its binding to the NDSM and renders a selective decrease in sumoylation of substrates with the NDSM motif. Here, we provide detailed structural, thermodynamic, and kinetics results of the interactions between Ubc9 and its K65 acetylated variant (Ac-Ubc9K65) with three NDSMs derived from Elk1, CBP, and Calpain2 to rationalize the mechanism beneath this reduced binding. Our nuclear magnetic resonance (NMR) data rule out a direct interaction between the NDSM and the K65 residue of Ubc9. Similarly, we found that NDSM binding was entropy-driven and unlikely to be affected by the negative charge by K65 acetylation. Moreover our NMR, mutagenesis and molecular dynamics simulation studies defined the sequence of the NDSM as Ψ-K-x-E/D-x1-x2-(x3/E/D)-(x4/E/D)-xn and determined that K74 and K76 were critical Ubc9 residues interacting with the negatively charged residues of the NDSM.

Ubc9 acetylation modulates distinct SUMO target modification and hypoxia response.

While numerous small ubiquitin-like modifier (SUMO) conjugated substrates have been identified, very little is known about the cellular signalling mechanisms that differentially regulate substrate sumoylation. Here, we show that acetylation of SUMO E2 conjugase Ubc9 selectively downregulates the sumoylation of substrates with negatively charged amino acid-dependent sumoylation motif (NDSM) consisting of clustered acidic residues located downstream from the core ψ-K-X-E/D consensus motif, such as CBP and Elk-1, but not substrates with core ψ-K-X-E/D motif alone or SUMO-interacting motif. Ubc9 is acetylated at residue K65 and K65 acetylation attenuates Ubc9 binding to NDSM substrates, causing a reduction in NDSM substrate sumoylation. Furthermore, Ubc9 K65 acetylation can be downregulated by hypoxia via SIRT1, and is correlated with hypoxia-elicited modulation of sumoylation and target gene expression of CBP and Elk-1 and cell survival. Our data suggest that Ubc9 acetylation/deacetylation serves as a dynamic switch for NDSM substrate sumoylation and we report a previously undescribed SIRT1/Ubc9 regulatory axis in the modulation of protein sumoylation and the hypoxia response.

Daxx interacts with and modulates the activity of CREB.

The phosphorylation of cAMP response element-binding protein (CREB) induced by the cAMP-dependent protein kinase A (PKA) elicits the recruitment of CREB-binding protein (CBP) for activating cAMP responsive gene expression. Several reports indicate that proteins binding to CREB and/or CBP play important roles in modulating the CREB-dependent transactivation. Here, we show that Daxx interacts with CREB and modulates CREB-mediated transcription. Daxx was identified as a CREB-interacting protein by a yeast two-hybrid screen. Depletion of endogenous Daxx by specific shRNA or overexpression of Daxx resulted in decreased or increased levels of the cAMP/PKA-induced reporter activity and target gene expression, respectively. In vitro and in vivo binding studies revealed that Daxx C-terminal domain binds to CREB basic leucine zipper domain. The binding of Daxx to CREB correlates with its repressive effect on a CRE-mediated reporter activity induced by forskolin or PKA. Furthermore, the results of electrophoresis mobility shift assays and chromatin immunoprecipitation experiments showed that Daxx attenuated the DNA binding potential of the CREB. Our study provides a previously undescribed role of Daxx in repressing cAMP-responsive gene expression and also a mechanism underlying the repressive effect of Daxx on CREB transcriptional potential.

Structural and functional roles of Daxx SIM phosphorylation in SUMO paralog-selective binding and apoptosis modulation.

Small ubiquitin-like modifier (SUMO) conjugation and interaction are increasingly associated with various cellular processes. However, little is known about the cellular signaling mechanisms that regulate proteins for distinct SUMO paralog conjugation and interactions. Using the transcriptional coregulator Daxx as a model, we show that SUMO paralog-selective binding and conjugation are regulated by phosphorylation of the Daxx SUMO-interacting motif (SIM). NMR structural studies show that Daxx (732)E-I-I-V-L-S-D-S-D(740) is a bona fide SIM that binds to SUMO-1 in a parallel orientation. Daxx-SIM is phosphorylated by CK2 kinase at residues S737 and S739. Phosphorylation promotes Daxx-SIM binding affinity toward SUMO-1 over SUMO-2/3, causing Daxx preference for SUMO-1 conjugation and interaction with SUMO-1-modified factors. Furthermore, Daxx-SIM phosphorylation enhances Daxx to sensitize stress-induced cell apoptosis via antiapoptotic gene repression. Our findings provide structural insights into the Daxx-SIM:SUMO-1 complex, a model of SIM phosphorylation-enhanced SUMO paralog-selective modification and interaction, and phosphorylation-regulated Daxx function in apoptosis.