Search

Caveolae are small plasma membrane invaginations, important for control of membrane tension, signaling cascades, and lipid sorting. The caveola coat protein Cavin1 is essential for shaping such high curvature membrane structures. Yet, a mechanistic understanding of how Cavin1 assembles at the membrane interface is lacking. Here, we used model membranes combined with biophysical dissection and computational modeling to show that Cavin1 inserts into membranes. We establish that initial phosphatidylinositol ( 4 , 5 ) bisphosphate [PI(4,5)P 2 ]–dependent membrane adsorption of the trimeric helical region 1 (HR1) of Cavin1 mediates the subsequent partial separation and membrane insertion of the individual helices. Insertion kinetics of HR1 is further enhanced by the presence of flanking negatively charged disordered regions, which was found important for the coassembly of Cavin1 with Caveolin1 in living cells. We propose that this intricate mechanism potentiates membrane curvature generation and facilitates dynamic rounds of assembly and disassembly of Cavin1 at the membrane.

Objective Neuroimaging studies have shown that patients with pain-related conditions have altered neuronal activity and structural functions. The purpose of this study was to investigate whether patients with classical trigeminal neuralgia (CTN) exhibit changes in corresponding neuronal activity via analysis of neuronal activity regional homogeneity (ReHo). Methods A total of 28 patients presenting with sore eyes (12 men and 16 women) were matched with 28 healthy controls (12 men and 16 women). All participants underwent functional magnetic resonance imaging (fMRI). This ReHo method was used to assess the consistency of changes in neural activity in various brain regions. The receiver operating characteristic (ROC) curve was applied to differentiate ReHo values of patients with CTN from ReHo values of healthy controls. Pearson's correlation analysis was applied to evaluate the correlation between ReHo values of different brain regions of patients with CTN and clinical manifestations. Results Compared with healthy controls, patients with CTN were found to have increased ReHo values in the inferior cerebellum bilaterally, right inferior temporal gyrus, right middle occipital gyrus, right fusiform gyrus, right superior frontal gyrus, and right precentral gyrus. ROC curve analysis of each brain region revealed near-perfect accuracy regarding the area under the curve. However, no correlation between ReHo values and clinical manifestations in patients with CTN was found. Conclusions CTN is associated with altered neuronal networks in different areas of the brain. ReHo values all possess different degrees of change, implying that CTN has a certain impact on cerebral function.

The aim of the present study was to investigate the effects of an amniotic membrane lacrimal stent in the treatment of dry eye syndrome in a perimenopausal rabbit model. In total, 48 healthy female rabbits were randomly divided into four groups (12 rabbits/group): Group A, sham-operated group; group B, negative control group; group C, sham-implantation group; and group D, implantation with amniotic membrane lacrimal stents. A Schirmer I test (SIT), corneal fluorescein staining, optical coherence tomography angiography and corneal confocal microscopy were conducted and the biomechanical properties of the amniotic membrane were measured prior to and 2, 4 and 6 weeks after the operations. There were marked differences in the amount of tear secretion and the SIT following the operation compared with prior to the operation. The amount of tear secretion of group B and C was significantly reduced (F=8.894; P=0.0017). Compared with groups A, B and C, group D demonstrated a significant increase in the amount of tear secretion and a significant reduction in SIT (P0.05). The cornea epithelial of groups A and D was significantly thinner compared with groups B and C. The superior part [superior temporal (ST)5, superior (S)5, superior nasal (SN)5, ST6, S6 and SN6] was significantly thinner compared with the central part of the cornea epithelium. The corneal epithelia of all groups were thin in the center and thick at the edge. At 6 weeks after the operation, group D exhibited a markedly decreased number of anterior stromal luminescent cells, compared with groups A, B and C. Furthermore, the bending degree of corneal stromal neural trunks was significantly improved, and the density, branches and curvature of corneal epithelium sub-basal nerves ameliorated to a certain extent (P

The haem‐containing mono‐oxygenase cytochrome P450 3A4 (CYP3A4) and its redox partner NADPH‐dependent cytochrome P450 oxidoreductase (CPR) are among the most important enzymes in human liver for metabolizing drugs and xenobiotic compounds. They are membrane‐bound in the endoplasmic reticulum (ER). How ER colocalization and the complex ER phospholipid composition influence enzyme activity are not well understood. CPR and CYP3A4 were incorporated into phospholipid bilayer nanodiscs, both singly, and together in a 1 : 1 ratio, to investigate the significance of membrane insertion and the influence of varying membrane composition on steady‐state reaction kinetics. Reaction kinetics were analysed using a fluorimetric assay with 7‐benzyloxyquinoline as substrate for CYP3A4. Full activity of the mono‐oxygenase system, with electron transfer from NADPH via CPR, could only be reconstituted when CPR and CYP3A4 were colocalized within the same nanodiscs. No activity was observed when CPR and CYP3A4 were each incorporated separately into nanodiscs then mixed together, or when soluble forms of CPR were mixed with preassembled CYP3A4‐nanodiscs. Membrane integration and colocalization are therefore essential for electron transfer. Liver microsomal lipid had an enhancing effect compared with phosphatidylcholine on the activity of CPR alone in nanodiscs, and a greater enhancing effect on the activity of CPR‐CYP3A4 nanodisc complexes, which was not matched by a phospholipid mixture designed to mimic the ER composition. Furthermore, liver lipid enhanced redox coupling within the system. Thus, natural ER lipids possess properties or include components important for enhanced catalysis by CPR‐CYP3A4 nanodisc complexes. Our findings demonstrate the importance of using natural lipid preparations for the detailed analysis of membrane protein activity.