The INAD scaffold is a dynamic, redox-regulated modulator of signaling in the Drosophila eye.

INAD is a scaffolding protein that regulates signaling in Drosophila photoreceptors. One of its PDZ domains, PDZ5, cycles between reduced and oxidized forms in response to light, but it is unclear how light affects its redox potential. Through biochemical and structural studies, we show that the redox potential of PDZ5 is allosterically regulated by its interaction with another INAD domain, PDZ4. Whereas isolated PDZ5 is stable in the oxidized state, formation of a PDZ45 "supramodule" locks PDZ5 in the reduced state by raising the redox potential of its Cys606/Cys645 disulfide bond by ∼330 mV. Acidification, potentially mediated via light and PLCß-mediated hydrolysis of PIP(2), disrupts the interaction between PDZ4 and PDZ5, leading to PDZ5 oxidation and dissociation from the TRP Ca(2+) channel, a key component of fly visual signaling. These results show that scaffolding proteins can actively modulate the intrinsic redox potentials of their disulfide bonds to exert regulatory roles in signaling.

Structures of the Human PGD2 Receptor CRTH2 Reveal Novel Mechanisms for Ligand Recognition.

The signaling of prostaglandin D2 (PGD2) through G-protein-coupled receptor (GPCR) CRTH2 is a major pathway in type 2 inflammation. Compelling evidence suggests the therapeutic benefits of blocking CRTH2 signaling in many inflammatory disorders. Currently, a number of CRTH2 antagonists are under clinical investigation, and one compound, fevipiprant, has advanced to phase 3 clinical trials for asthma. Here, we present the crystal structures of human CRTH2 with two antagonists, fevipiprant and CAY10471. The structures, together with docking and ligand-binding data, reveal a semi-occluded pocket covered by a well-structured amino terminus and different binding modes of chemically diverse CRTH2 antagonists. Structural analysis suggests a ligand entry port and a binding process that is facilitated by opposite charge attraction for PGD2, which differs significantly from the binding pose and binding environment of lysophospholipids and endocannabinoids, revealing a new mechanism for lipid recognition by GPCRs.

Structural basis of ELKS/Rab6B interaction and its role in vesicle capturing enhanced by liquid-liquid phase separation.

ELKS proteins play a key role in organizing intracellular vesicle trafficking and targeting in both neurons and non-neuronal cells. While it is known that ELKS interacts with the vesicular traffic regulator, the Rab6 GTPase, the molecular basis governing ELKS-mediated trafficking of Rab6-coated vesicles, has remained unclear. In this study, we solved the Rab6B structure in complex with the Rab6-binding domain of ELKS1, revealing that a C-terminal segment of ELKS1 forms a helical hairpin to recognize Rab6B through a unique binding mode. We further showed that liquid-liquid phase separation (LLPS) of ELKS1 allows it to compete with other Rab6 effectors for binding to Rab6B and accumulate Rab6B-coated liposomes to the protein condensate formed by ELKS1. We also found that the ELKS1 condensate recruits Rab6B-coated vesicles to vesicle-releasing sites and promotes vesicle exocytosis. Together, our structural, biochemical, and cellular analyses suggest that ELKS1, via the LLPS-enhanced interaction with Rab6, captures Rab6-coated vesicles from the cargo transport machine for efficient vesicle release at exocytotic sites. These findings shed new light on the understanding of spatiotemporal regulation of vesicle trafficking through the interplay between membranous structures and membraneless condensates.

Numerical investigation of effective nonlinear coefficient model for coupled third harmonic generation.

In this paper, the optimal solution of effective nonlinear coefficient of quasi-phase-matching (QPM) crystals for coupled third harmonic generation (CTHG) was numerically investigated. The effective nonlinear coefficient of CTHG was converted to an Ising model for optimizing domain distributions of aperiodically poled lithium niobate (APPLN) crystals with lengths as 0.5 mm and 1 mm, and fundamental wavelengths ranging from 1000 nm to 6000 nm. A method for reconstructing crystal domain poling weight curve of coupled nonlinear processes was also proposed, which demonstrated the optimal conversion ratio between two coupled nonlinear processes at each place along the crystal. In addition, by applying the semidefinite programming, the upper bound on the effective nonlinear coefficients deff for different fundamental wavelengths were calculated. The research can be extended to any coupled dual χ(2) process and will help us to understand better the dynamics of coupled nonlinear interactions based on QPM crystals.

Consideration of non-phase-matched nonlinear effects in the design of quasi-phase-matching crystals for optical parametric oscillators.

Femtosecond optical parametric oscillators (OPOs) are widely used in ultrafast nonlinear frequency conversion and quantum information. However, conventional OPOs based on quasi-phase-matching (QPM) crystals have many parasitic non-phase-matched processes which decrease the conversion efficiency. Here, we propose nine-wave coupled equations (NWCEs) to simulate all phase-matched and non-phase-matched interactions in QPM crystals to improve conventional three-wave coupled equations (TWCEs), especially for the situation of high intensity ultrashort pulses and complexly structured crystals. We discuss how to design the poling period of QPM crystal to maximize the conversion efficiency of signal light for a given OPO system. The simulation reveals that the OPO based on chirped periodically poled lithium niobate (CPPLN) with a certain chirp rate has higher signal wave conversion efficiency than that of a PPLN, and demonstrates that NWCEs illustrate more details of the pulse evolution in the OPO cavity. Starting from a CPPLN, an aperiodically poled lithium niobate (APPLN) design is available by modifying the domain lengths of the crystal and optimizing the OPO output power via dynamical optimization algorithm. The results show that by using a properly designed APPLN crystal, a 1600 nm OPO, when pumped by a femtosecond laser with 1030 nm central wavelength, 150 femtosecond pulse duration and 5 GW/cm2 power intensity at the focus, can achieve very efficient output with a signal light conversion efficiency of 50.6%, which is higher than that of PPLN (25.2%) and CPPLN (40.2%). The scheme in this paper will provide a reference for the design of nonlinear QPM crystals of OPOs and will help to understand the complex nonlinear dynamical behavior in OPO cavities.

Myosin VI undergoes cargo-mediated dimerization.

Myosin VI is the only known molecular motor that moves toward the minus ends of actin filaments; thus, it plays unique roles in diverse cellular processes. The processive walking of myosin VI on actin filaments requires dimerization of the motor, but the protein can also function as a nonprocessive monomer. The molecular mechanism governing the monomer-dimer conversion is not clear. We report the high-resolution NMR structure of the cargo-free myosin VI cargo-binding domain (CBD) and show that it is a stable monomer in solution. The myosin VI CBD binds to a fragment of the clathrin-coated vesicle adaptor Dab2 with a high affinity, and the X-ray structure of the myosin VI CBD in complex with Dab2 reveals that the motor undergoes a cargo-binding-mediated dimerization. The cargo-binding-induced dimerization may represent a general paradigm for the regulation of processivity for myosin VI as well as other myosins, including myosin VII and myosin X.

Effect of collagen sponge combined with epidermal growth factor in repairing maxillofacial head and neck wounds in rats.

Collagen sponge and epidermal growth factor (EGF) promote wound healing. However, the effect of collagen sponge combined with EGF in repairing maxillofacial head and neck wounds remains unclear. The rats were divided into 3 groups, including experimental group 1 (Vaseline gauze+EGF), experimental group 2 (collagen sponge+EGF) with control group (Vaseline+normal saline), and maxillofacial head and neck wounds were simulated. Wound pathological morphology was detected by HE staining; wound EGF, IL-1ß, IL-6 along with TNF-α contents by ELISA and MMP1 level by western blot. At 7 and 14 days after treatment, wound healing rate of two experimental groups was higher than that of control group, and that of experimental group 2 presented higher than that of experimental group 1. Compared with control group, experimental group 1 had significantly fewer inflammatory cells in the wound tissue, local erythrocyte spillage outside the vascular walls, more collagen deposition and more granulation tissue. Compared with experimental group 1, inflammatory cells in wound tissues of experimental group 2 were significantly reduced, the collagen tissues were visible and arranged, and the growth of the wound granulation tissue was obvious. IL-1ß, IL-6 along with TNF-α levels in two experimental groups presented lower than control group, and EGF level was higher. More importantly, in contrast to experimental group 1, IL-1ß, IL-6 along with TNF-α in experimental group 2 presented lower, and EGF level presented higher. At 14 days after treatment, MMP1 level in two experimental groups was lower than control group. In contrast to experimental group 1, MMP1 level in experimental group 2 was lower. In summary, collagen sponge combined with EGF for the first time significantly improved the healing speed of maxillofacial head and neck wounds and reduced the scar left after wound healing.

The Effect of NPWT on Odontogenic Cervical Necrotizing Fasciitis.

OBJECTIVE: To investigate the clinical efficacy of negative pressure wound therapy (NPWT) in the treatment of odontogenic cervical Necrotizing fasciitis (CNF). METHODS: Sixteen cases of odontogenic cervical necrotizing fasciitis were randomly divided into observation group and control group after routine debridement and disinfection. The patients in the control group were treated with drainage tube and regular dressing changes, while those in the observation group were treated with NPWT. The therapeutic effects of the 2 groups were compared. RESULTS: The frequency of operation, treatment length, and cost of treatment in the observation group were significantly less than those in the control group (P<0.05). During the treatment, the VAS (visual analog scale of pain) in the observation group was significantly lower than that in the control group (P<0.05). The levels of WBC, CRP, PCT, IL-6, and TNF-α in the observation group were lower than those in the control group (P<0.05). The levels of Il-10 and VEGF in the observation group were higher than those in the control group (P<0.05), the difference was statistically significant. CONCLUSIONS: The condition of odontogenic cervical necrotizing fasciitis progresses rapidly. Compared with conventional drainage and dressing change, NPWT can control infection in a short time, reduce operation frequency and treatment cost, and promote wound healing, shorten the treatment time, ease the pain of patients, improve the quality of life. The therapeutic scheme is safe, effective, and suitable for clinical application.

Clinical Study of Rh-bFGF Combined With Collagen Sponge in the Treatment of Maxillofacial Deep â ¡ Degree Burn.

OBJECTIVES: To observe the clinical effect of recombinant human alkaline fibroblast growth factor (rh-bFGF) combined with collagen sponge in the treatment of maxillofacial deepⅡ degree burn. METHODS: From January 2019 to January 2022, 96 patients with maxillofacial deep Ⅱ degree burns were randomly divided into a control group (N=48) and an observation group (N=48). The observation group was treated with rh-bFGF and collagen sponge after debridement, whereas the control group was treated with silver sulfadiazine ointment after debridement. The healing rate and healing time of the wounds were observed, interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-10, epidermal growth factor (EGF), endothelial growth factor growth factor (VEGF), and metalloproteinase tissue inhibitor 1 (TIMP-1) were measured. Vancouver Scar Scale (VSS) was used to evaluate the local scar at 6 months after wound healing in both groups. RESULTS: On the 10th, 14th, and 21st day of treatment, the wound healing rate in the observation group was higher than that in the control group (P<0.05), the wound healing time in the observation group was lower than that in the control group (P<0.05), and on the 14th day of treatment, the levels of TNF-α and IL-6 in the observation group were lower than those in the control group (P<0.05). The levels of IL-10 in the observation group were higher than those in the control group (P<0.05). The levels of EGF, VEGF, and TIMP-1 in the observation group were higher than those in the control group (P<0.05), and the scores of VSS in the observation group were lower than those in the control group (P<0.05). CONCLUSIONS: Rh-bFGF combined with collagen sponge can decrease the levels of TNF-α and IL-6 and increase the levels of IL-10, which can control the inflammation effectively, at the same time, it can increase the level of EGF, VEGF, and TIMP-1, promote wound healing, and reduce scar hyperplasia. The treatment protocol is simple, safe, effective, and suitable for clinical application.

High average power amplification of femtosecond pulses based on the Yb:CaYAlO4 crystal.

In this paper, we demonstrated the direct amplification of femtosecond pulses with the Yb:CaYAlO4 crystal for the first time. A compact and simple two-stage amplifier delivered amplified pulses with the average powers of 55.4 W for σ-polarization and 39.4 W for π-polarization at the center wavelengthes of 1032 nm and 1030 nm, corresponding to 28.3% and 16.3% optical-to-optical efficiencies, respectively. These are to the best of our knowledge the highest value achieved with a Yb:CaYAlO4 amplifier. Upon using a compressor consisting of prisms and GTI mirrors, a pulse duration of 166-fs was measured. Thanks to the good thermal management, the beam quality (M2) parameters <1.3 along each axis were maintained in each stage.