Protein and Peptide Letters - Volume 30, Issue 11, 2023

Gap junction (GJ) is a special cell membrane structure composed of connexin. Connexin is widely distributed and expressed in all tissues except differentiated skeletal muscle, red blood cells, and mature sperm cells, which is related to the occurrence of many genetic diseases due to its mutation. Its function of regulating immune response, cell proliferation, migration, apoptosis, and carcinogenesis makes it a therapeutic target for a variety of diseases. In this paper, the possible mechanism of its action in nervous system-related diseases and treatment are reviewed.

Alzheimer's disease, a neurodegenerative disease, is a progressive and irreversible disease that has become a global challenge due to its increasing prevalence and absence of available potential therapies. Protein misfolding and aggregation are known to be the root of several protein neurodegenerative diseases, including Alzheimer's disease. Protein aggregation is a phenomenon where misfolded proteins accumulate and clump together intra-or extracellularly. This accumulation of misfolded amyloid proteins leads to the formation of plaquesin the neuronal cells, also known as amyloid β plaques. The synthesis of amyloid β plaques and tau protein aggregation are the hallmarks of Alzheimer's disease. Potential therapeutics must be developed in conjunction with an understanding of the possible root cause involving complex mechanisms. The development of therapeutics that can inhibit protein misfolding and aggregation, involved in the pathogenesis of Alzheimer's disease, could be one of the potential solutions to the disease.

This review describes the specific features of families of Conus venom peptides (conotoxins or conopeptides) that represent twelve pharmacological classes. Members of these conopeptide families are targeted to voltage-gated ion channels, such as calcium, sodium, and potassium channels. The conopeptides covered in this work include omega-conotoxins and contryphans with calcium channels as targets; mu-conotoxins, muO-conotoxins, muP-conotoxins, delta-conotoxins and iota-conotoxin with sodium channels as targets; and kappa-conotoxins, kappaM-conotoxins, kappaO-conotoxin, conkunitzins, and conorfamide with potassium channels as targets. The review covers the peptides that have been characterized over the last two decades with respect to their physiological targets and/or potential pharmacological applications, or those that have been discovered earlier but with noteworthy features elucidated in more recent studies. Some of these peptides have the potential to be developed as therapies for nerve, muscle, and heart conditions associated with dysfunctions in voltage-gated ion channels. The gating process of an ion channel subtype in neurons triggers various biological activities, including regulation of gene expression, contraction, neurotransmitter secretion, and transmission of electrical impulses. Studies on conopeptides and their interactions with calcium, sodium, and potassium channels provide evidence for Conus peptides as neuroscience research probes and therapeutic leads.

Background: Increasingly convincing evidence has revealed that circular RNAs (circRNAs) are critical regulatory components of hepatocellular carcinoma (HCC) genesis. However, the expression of circRNAs in HCC and the relevance of circRNAs to HCC progression remain largely unexplained.Methods: qRT-PCR or western blotting was utilized to confirm circ_0001687, miR-140-3p, and Forkhead Box q1 (FOXQ1) levels in HCC tissues or cells. Cell proliferation ability was evaluated via CCK-8 and colony formation assay. The correlation of circ_0001687 or FOXQ1 and miR-140- 3p was determined using dual luciferase reporter assay. Nude mice xenograft tumor model was constructed to verify the effect of circ_0001687 on tumor growth.Results: Circ_0001687 was elevated in HCC. Function assays and the nude mice xenograft tumor model indicated that circ_0001687 acts as a promoting gene in HCC to regulate the proliferation of the tumor cell and foster tumor growth. Further mechanistic exploration revealed that the tumor growth-promoting mechanism of circ_0001687 relied on blocking the inhibitory effect of miR-140- 3p on FOXQ1 and activating FOXQ1 expression.Conclusion: This research indicated the role of circ_0001687/miR-140-3p/FOXQ1 network in regulating HCC development. These may provide new insights into the treatment of HCC.

Background: UDP-glucuronosyltransferases (UGTs) play a crucial role in maintaining endobiotic homeostasis and metabolizing xenobiotic compounds, particularly clinical drugs. However, the detailed catalytic mechanism of UGTs has not been fully elucidated due to the limited availability of reliable protein structures. Determining the catalytic domain of human UGTs has proven to be a significant challenge, primarily due to the difficulty in purifying and crystallizing the full-length protein. Objectives: This study focused on the human UGT2B10 C-terminal cofactor binding domain, aiming to provide structural insights into the fundamental catalytic mechanisms. Methods: In this study, the C-terminal sugar-donor binding domain of human UGT2B10 was purified and crystallized using the vapor-diffusion method. The resulting UGT2B10 CTD crystals displayed high-quality diffraction patterns, allowing for data collection at an impressive resolution of 1.53 Å using synchrotron radiation. Subsequently, the structure of the UGT2B10 CTD was determined using the molecule replacement method with a homologous structure. Results: The crystals were monoclinic, belonging to the space C2 with unit-cell parameters a =85.90 Å, b = 58.39 Å, c = 68.87 Å, α = γ = 90°, and β = 98.138°. The Matthews coefficient VM was determined to be 2.24 Å3 Da-1 (solvent content 46.43%) with two molecules in the asymmetric unit. Conclusion: The crystal structure of UGT2B10 CTD was solved at a high resolution of 1.53 Å, revealing a conserved cofactor binding pocket. This is the first study determining the C-terminal cofactor binding domain of human UGT2B10, which plays a key role in additive drug metabolism.

Introduction: The anti-angiogenic agent vascular endothelial growth factor 165b (VEGF165b) mutant (mVEGF165b), which was developed by our laboratory, has superior antitumor activity to that of native VEGF165b; however, its mechanism of action and druggability need further exploration.Methods: Using the commercial anti-angiogenic drug bevacizumab as a positive control, the mechanism and developability of mVEGF165b were evaluated and explored. The Cell Counting Kit-8 assay was performed to evaluate the effects of mVEGF165b and bevacizumab alone on the proliferation of human umbilical vein endothelial cells (HUVECs). Meanwhile, the inhibitory effects of mVEGF165b and bevacizumab combined with paclitaxel in a mouse model of breast cancer were assessed. Immunohistochemistry was used to detect their effects on tumor vascular maturation, and the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was used to detect the apoptosis of tumor cells.Results: In vitro cell experiments confirmed that mVEGF165b inhibited the proliferation of HUVECs with an efficacy equivalent to that of bevacizumab. mVEGF165b and bevacizumab combined with paclitaxel significantly delayed the growth of breast cancer in mice. Immunohistochemistry and the TUNEL assay showed that mVEGF165b and bevacizumab combined with paclitaxel-induced higher vascular maturity and more apoptosis than paclitaxel alone.Conclusion: mVEGF165b showed similar efficacy and mechanism of action as bevacizumab, indicating its potential to be developed into a safe and effective anti-angiogenic drug.

Background: LinB, as a Haloalkane dehalogenase, has good catalytic activity for many highly toxic and recalcitrant compounds, and can realize the elimination of chemical weapons HD in a green non-toxic mode.Objectives: In order to display Haloalkane dehalogenase LinB on the surface of Bacillus subtilis spore.Methods: We have constituted the B. subtilis spore surface display system of halogenated alkanes dehalogenase LinB by gene recombination.Results: Data revealed that LinB can display on spore surface successfully. The hydrolyzing HD analogue 2-chloroethyl ethylsulfide (2-CEES) activity of displayed LinB spores was 4.30±0.09 U/mL, and its specific activity was 0.78±0.03U/mg. Meanwhile, LinB spores showed a stronger stress resistance activity on 2-CEES than free LinB. This study obtained B. subtilis spores of LinB (phingobium japonicum UT26) with enzyme activity that was not reported before.Conclusion: Spore surface display technology uses resistance spore as the carrier to guarantee LinB activity, enhances its stability, and reduces the production cost, thus expanding the range of its application.

Background: Gastric cancer (GC) is a malignant tumor with seriously poor outcomes. Studies have shown that microRNAs (miRNAs) play an omnifarious regulatory effect in GC. However, the role of miR-3650 in the progression of GC is not well known.Methods: In this study, miR-3650 expression and its clinical significance were determined using clinical specimens. The biological functions of miR-3650 were determined in gastric cancer cell lines through CCK-8, cell scratch, and transwell experiments. Bioinformatics predictions, combined with Western blot experiments, were employed to explore its downstream molecular targets.Results: We observed that miR-3650 was overexpressed in GC specimens and most cell lines, i.e., 77.8% (MKN28, SNU1, AGS, MKN45, N87, BGC823 and SGC7901). The overexpression correlated with advanced T-stage, N-stage, M-stage, and TNM-stage. Furthermore, miR-3650 promoted the proliferation and migration of gastric cancer cells, and its overexpression promoted the PI3K-AKT-mTOR pathway and inhibited the PTEN and hippo pathways. The potassium ion signaling pathway was also involved in the biological process of miR-3650 promoting cancer.Conclusion: Therefore, we concluded that miR-3650/PTEN/PI3K-AKT-mTOR and miR-3650/hippo pathways are vital in the progression of GC and serve as novel targets for GC therapy.