Spectral Characteristics and Functional Responses of Phospholipid Bilayers in the Terahertz Band.

Understanding the vibrational information encoded within the terahertz (THz) spectrum of biomolecules is critical for guiding the exploration of its functional responses to specific THz radiation wavelengths. This study investigated several important phospholipid components of biological membranes-distearoyl phosphatidylethanolamine (DSPE), dipalmitoyl phosphatidylcholine (DPPC), sphingosine phosphorylcholine (SPH), and lecithin bilayer-using THz time-domain spectroscopy. We observed similar spectral patterns for DPPC, SPH, and the lecithin bilayer, all of which contain the choline group as the hydrophilic head. Notably, the spectrum of DSPE, which has an ethanolamine head group, was different. Interestingly, density functional theory calculations confirmed that the absorption peak common to DSPE and DPPC at approximately 3.0 THz originated from a collective vibration of their similar hydrophobic tails. Accordingly, the cell membrane fluidity of RAW264.7 macrophages with irradiation at 3.1 THz was significantly enhanced, leading to improved phagocytosis. Our results highlight the importance of the spectral characteristics of the phospholipid bilayers when studying their functional responses in the THz band and suggest that irradiation at 3.1 THz is a potential non-invasive strategy to increase the fluidity of phospholipid bilayers for biomedical applications such as immune activation or drug administration.

0.1 THz exposure affects primary hippocampus neuron gene expression via alternating transcription factor binding.

In recent years, many studies have been conducted to investigate the influence of terahertz (THz) radiation on the gene expression in various cell types, but the underling molecular mechanism has not yet been fully revealed. In this study, we explored the effects of 0.1 THz radiation on the gene expression in primary neuron cells through RNA-seq analysis. 111 up-regulated and 54 down-regulated genes were identified. Several biomolecule binding related categories such as "long-chain fatty acid binding", "tropomyosin binding", "BMP receptor binding", as well as "GTPase binding" and "phospholipid binding" were enriched by GO analysis. Moreover, the GSEA analysis indicated that genes encoding protein biosynthetic machinery ribosome were up-regulated by 0.1 THz irradiation. In addition, we demonstrated that the binding efficiency of a transcription factor (TF) AP-1 with its transcription factor binding site (TFBS) in DNA was reduced by THz irradiation, which suggested that THz irradiation might affect the interaction between TFs with DNA and consequently regulate the gene expression. Our results provide new insights into the biological effects of terahertz irradiation.

Functionalized polyhydroxyalkanoate nano-beads as a stable biocatalyst for cost-effective production of the rare sugar d-allulose.

d-Allulose is a promising low-calorie sweetener especially for diabetes and obesity patients. The functionalized polyhydroxyalkanoate (PHA) nano-beads decorated with d-tagatose 3-epimerase (DTE) was produced in recombinant endotoxin-free ClearColi, whereby the expression, purification, and immobilization of the active DTE were efficiently combined into one step. The immobilized DTE exhibited remarkable enzyme activity of 649.3 U/g beads and extremely high stability at a harsh working condition (pH 7.0-8.0, 65 °C). When DTE-PHA beads were subjected to enzymatic synthesis of d-allulose, a maximum conversion rate of 33% can be achieved at pH 7.0 and 65 °C for 3 h, and DTE-PHA beads retained about 80% of its initial activity after 8 continuous cycles. Moreover, the d-allulose/d-fructose binary mixture can be simply separated by a single cation exchange resin-equipped chromatography. Taken together, DTE-PHA beads are promising and robust nano-biocatalysts that will remarkably simplify the production procedures of d-allulose, contributing to its cost-effective production.

Inhibition of PI3Kγ by AS605240 Protects tMCAO Mice by Attenuating Pro-Inflammatory Signaling and Cytokine Release in Reactive Astrocytes.

The intense and prolonged inflammatory response after ischemic stroke significantly contributes to the secondary neural injury. PI3Kγ, which is involved in the regulation of vascular permeability, chemotactic leukocyte migration and microglia activation, is a key target for intervention in the inflammatory response. In this study, we identified the protective effect of the PI3Kγ inhibitor AS605240 against stroke-related injury in the mouse model of transient intraluminal middle cerebral artery occlusion (tMCAO). The results showed that administration of AS605240 could improve the neurological function score, reduce the infarct size and decrease astrocyte activation in the tMCAO mice after injury. The inhibitory effect of AS605240 on microglia activation is relatively clear. Therefore, in this study, the effects of AS605240 on astrocytes were studied in cell cultures. IL-6 and its soluble receptor were used to construct the astrocyte activation model. AS605240 treatment significantly reduced the astrocyte activation markers and the morphological changes of cells. We also identified 13 inflammatory factors whose expression was significantly upregulated by IL-6/sIL-6R and significantly inhibited by AS605240 at the protein level, and seven of those factors were verified at the mRNA level. These results indicated that specific inhibition of PI3Kγ could reduce astrocyte activation induced by inflammation, which might aid the repair and remodeling of neurons in the later stage after ischemic stroke.

PHBHHx Facilitated the Residence, Survival and Stemness Maintain of Transplanted Neural Stem Cells in Traumatic Brain Injury Rats.

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is a polyhydroxyalkanoate (PHA) with broad application prospects in various biomedical fields. Our previous study demonstrated the great biocompatibility of PHBHHx with neural stem cells (NSCs) in vitro. In this study, we went a step further and implanted the NSC-carrying PHBHHx film to in vivo into the lesion region in a rat traumatic brain injury (TBI) model. The in vivo biocompatibility of PHBHHx, as well as the survival, migration and differentiation of the transplanted NSCs were investigated. The results showed that PHBHHx did not induce additional reactive gliosis and supported the in vivo survival and growth of the transplanted stem cells. The transplanted NSCs were able to migrate into the brain tissue and differentiated into both neurons and astrocytes. Moreover, PHBHHx seemed to be able to maintain the stemness of the attached NSCs both in vitro and in vivo. The major monomer of PHBHHx, 3-hydroxybutyrate (3-HB), might contribute to this bioactivity because the addition of low concentrations of 3-HB facilitated the self-renewal of NSCs by shortening the G1 phase, promoted their proliferation, and enhanced the expression of a key regulatory transcription factor which helped to keep the stemness of NSCs. These results highlight the application of PHBHHx as a promising bioactive material for NSC transplantation in the brain and open up a wide space for further studies on functional recovery following the transplantation of NSCs attached to PHBHHx.

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) Biopolyester Based Nanoparticles as NVP-BEZ235 Delivery Vehicle for Tumor Targeting Therapy.

As a biopolyester with excellent properties, the potential biomedical applications of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) have gained extensive attention. In this research, PHBHHx was fabricated into nanoparticles (NPs) to encapsulate NVP-BEZ235 (BEZ), an efficient kinase inhibitor/antitumor agent, for tumor targeting therapy. The resulting BEZ-NPs displayed a regularly spherical form with an appropriate diameter at 76.0 ± 3.6 nm. The encapsulation efficiency of BEZ was 83.7 ± 3.6%, and the sustained release profiles showed that almost 97% of BEZ could be gradually unrestricted from PHBHHx NPs within 72 h. The nanotoxicity studies revealed a satisfactory biosafety of PHBHHx NPs. PHBHHx NPs presented significantly improved cellular uptake in human prostate cancer cell line PC3, thereby enhancing the antiproliferation ability and kinase inhibitory activity of BEZ in vitro. More importantly, the in vivo real-time imaging demonstrated the adequate tumor targeting and accumulation capability of PHBHHx NPs. The remarkably delayed tumor growth, increased tumor necrosis, and reduced tumor proliferation in PC3 tumor xenograft mice further confirmed the antitumor efficacies of BEZ-loaded PHBHHx NPs. The above results suggest that PHBHHx NPs might be a promising drug delivery vehicle, safe and effective, for tumor targeting therapy.

Beta-hydroxybutyrate Promotes the Expression of BDNF in Hippocampal Neurons under Adequate Glucose Supply.

Neurobiological evidence suggests that the ketone metabolite ß-hydroxybutyrate (BHBA) exerts many neuroprotective functions for the brain. The previous study revealed that BHBA could promote the expression of brain-derived neurotrophic factor (BDNF) at glucose inadequate condition. Here we demonstrated that BHBA administration induced the expression of BDNF in the hippocampus of mice fed with normal diet. In vitro experiment results also showed that 0.02-2 mM BHBA significantly increased BDNF expression in both the primary hippocampal neurons and the hippocampus neuron cell line HT22 under adequate glucose supply. Bdnf transcription induced by BHBA stimulus was mediated through the cAMP/PKA-triggered phosphorylation of CREB (S133) and the subsequent up-regulation of histone H3 Lysine 27 acetylation (H3K27ac) binding at Bdnf promoters I, II, IV, and VI. Moreover, BHBA stimulus induced a decrease in tri-methylation of H3K27 (H3K27me3) binding at the Bdnf promoters II and VI and the elevation of H3K27me3-specific demethylase JMJD3, which also contributed to the activation of Bdnf transcription. These results demonstrated that BHBA within the physiological range could promote BDNF expression in neurons via a novel signaling function. Moreover, BHBA might possess more broad epigenetic regulatory activities, which affected both the acetylation and demethylation of H3K27. Our findings reinforce the beneficial effect of BHBA on the central nervous system (CNS) and suggest that BHBA administration with no need for energy restriction might also be a promising intervention to improve the neuronal activity and ameliorate the degeneration of CNS.

A Specific Drug Delivery System for Targeted Accumulation and Tissue Penetration in Prostate Tumors Based on Microbially Synthesized PHBHHx Biopolyester and iRGD Peptide Fused PhaP.

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is an intracellular biopolyester synthesized by various bacteria. Polyhydroxyalkanoate granule-binding protein (PhaP), a natural biomacromolecule symbiotic with PHBHHx, can be steadily adsorbed into the PHBHHx matrix through hydrophobic interactions. In this study, PHBHHx nanoparticles (NPs) and iRGD peptide fused PhaP (iRGD-PhaP) were used in conjunction to build a specific drug delivery system for targeted accumulation and tissue penetration in prostate tumors. A proper presentation and high surface density of iRGD could be ensured within 1 h through a convenient coincubation method using a PhaP-mediated modification strategy. iRGD-PhaP-NPs showed a satisfactory particle size (182.9 ± 4.9 nm) and slightly negative surface charge (-17.2 ± 0.3 mV), with a uniformly spherical shape. In human prostate cancer cell line PC3, iRGD-PhaP-NPs displayed remarkably improved cellular uptake compared to naked NPs, which was attributed to iRGD receptor-mediated active endocytosis. Enhanced targeted accumulation and retention of iRGD-PhaP-NPs in prostate tumors were found in both the ex vivo tumor spheroid assay and in vivo real-time imaging. Moreover, slices of the tumor deep region demonstrated the favorable tumor penetration ability of iRGD-PhaP-NPs after intravenous administration. These results highlight the specificity and efficiency of iRGD-PhaP-NPs in future clinical use.