Hexokinase 1 cellular localization regulates the metabolic fate of glucose.

The product of hexokinase (HK) enzymes, glucose-6-phosphate, can be metabolized through glycolysis or directed to alternative metabolic routes, such as the pentose phosphate pathway (PPP) to generate anabolic intermediates. HK1 contains an N-terminal mitochondrial binding domain (MBD), but its physiologic significance remains unclear. To elucidate the effect of HK1 mitochondrial dissociation on cellular metabolism, we generated mice lacking the HK1 MBD (ΔE1HK1). These mice produced a hyper-inflammatory response when challenged with lipopolysaccharide. Additionally, there was decreased glucose flux below the level of GAPDH and increased upstream flux through the PPP. The glycolytic block below GAPDH is mediated by the binding of cytosolic HK1 with S100A8/A9, resulting in GAPDH nitrosylation through iNOS. Additionally, human and mouse macrophages from conditions of low-grade inflammation, such as aging and diabetes, displayed increased cytosolic HK1 and reduced GAPDH activity. Our data indicate that HK1 mitochondrial binding alters glucose metabolism through regulation of GAPDH.

Phosphodiesterase 5 inhibitors: preclinical and early-phase breakthroughs for impotence treatments.

INTRODUCTION: Erectile dysfunction (ED) is a condition that affects millions of men worldwide and is characterized by the inability to achieve or maintain an erection for satisfactory sexual performance. There are numerous treatment options for ED, including medications, mechanical assist devices, and surgical management; however, first-line treatment is usually a phosphodiesterase 5 (PDE5) inhibitor. There is a growing interest in developing novel, efficacious PDE5 inhibitors that provide better quality, safety, and tolerability profiles with less adverse effects. Our review of udenafil, mirodenafil, youkenafil, lodenafil, and SLx-2101 analyzes the safety, efficacy, and pharmacokinetic properties of these new ED drugs. AREAS COVERED: Clinical trials demonstrated improved scores in questionnaires, such as the International Index of Erectile Function and Sexual Encounter Profile, for udenafil, mirodenafil, and lodenafil, while youkenafil and SLx-2101 revealed enhanced safety and tolerability in early pharmacokinetic studies. EXPERT OPINION: It is our opinion that more robust clinical trials are required before these medications can be made available in the United States. Additionally, the field of urology may benefit from pursuing other avenues of pharmacotherapy, such as injections, tablets with a different mechanism of action, or stem cell therapy, to restore the integrity of the endothelium within the penis.

Optimized protocol to isolate primary mouse peritoneal macrophage metabolites.

Peritoneal macrophages (PMs) have been shown to have higher stability compared to other macrophage subtypes. However, obtaining enough PMs from a single mouse is often a limitation for metabolomics analysis. Here, we describe a protocol to isolate metabolites from a small number of mouse primary PMs for 13C-stable glucose tracing and metabolomics. Our protocol uses X for metabolite extraction instead of methanol. Our protocol can consistently extract metabolites from low cell number samples with fewer steps than methanol-based approaches. For complete details on the use and execution of this protocol, please refer to De Jesus et al., (2022).

N6-adenomethylation of GsdmC is essential for Lgr5+ stem cell survival to maintain normal colonic epithelial morphogenesis.

Gut epithelial morphogenesis is maintained by intestinal stem cells. Here, we report that depletion of N6-adenosine methyltransferase subunit Mettl14 from gut epithelial cells in mice impaired colon mucosal morphogenesis, leading to increased mucosal permeability, severe inflammation, growth retardation, and premature death. Mettl14 ablation triggered apoptosis that depleted Lgr5+ stem cells and disrupted colonic organoid growth and differentiation, whereas the inhibition of apoptosis rescued Mettl14-deleted mice and organoids. Mettl14 depletion disrupted N6-adenomethylation on GsdmC transcripts and abolished GsdmC expression. Reconstitution of Mettl14-deleted organoids or mice with GSDMC rescued Lgr5 expression and prevented apoptosis and mouse premature death, whereas GSDMC silence eliminated LGR5 and triggered apoptosis in human colonic organoids and epithelial cells. Mechanistically, Mettl14 depletion eliminated mitochondrial GsdmC, disrupted mitochondrial membrane potential, and triggered cytochrome c release that activates the pro-apoptotic pathway. In conclusion, GsdmC N6-adenomethylation protects mitochondrial homeostasis and is essential for Lgr5+ cell survival to maintain normal colonic epithelial regeneration.

A protocol for macrophage depletion and reconstitution in a mouse model of sepsis.

Macrophages are key innate immune cells involved in a broad spectrum of physiological and pathological processes. Macrophage depletion with clodronate-liposomes is commonly used to investigate in vivo functions of macrophages in mice. Here, we describe a protocol that combines the depletion of resident macrophages with the reconstitution of the mice with in vitro differentiated, lentivirus-transduced bone marrow-derived macrophages (BMDMs) in the context of an experimental sepsis model. This experimental strategy is easily adapted to other experimental designs. For complete details on the use and execution of this protocol, please refer to Du et al. (2020).

Renin Promotes STAT4 Phosphorylation to Induce IL-17 Production in Keratinocytes of Oral Lichen Planus.

Interleukin-17 (IL-17) is highly expressed in the epithelial layer of oral lichen planus (OLP), but the underlying mechanism for IL-17 overexpression remains unknown. Here, we identify renin that is induced by NF-κB pathway contributes to the increase of IL-17 in human oral keratinocytes (HOKs). We describe that the release of cellular renin leads to the phosphorylation of Janus kinase 2 (JAK2) protein. The phosphorylated JAK2 recruits and activates the signal transducer and activator of transcription 4 (STAT4) by phosphorylating STAT4's tyrosine residue 693 (Tyr693). The now-activated STAT4 translocates into nucleus and binds to the promoter region of IL-17 gene in HOKs. Genetic interference of renin restores IL-17 levels in OLP cell models. Collectively, our results reveal that renin upregulates IL-17 expression by enhancing STAT4 phosphorylation. This discovery unveils an underpinning by which IL-17 is increased in oral keratinocytes and provides potential targeted therapies for OLP patients.

N6-Adenosine Methylation of Socs1 mRNA Is Required to Sustain the Negative Feedback Control of Macrophage Activation.

Bacterial infection triggers a cytokine storm that needs to be resolved to maintain the host's wellbeing. Here, we report that ablation of m6A methyltransferase subunit METTL14 in myeloid cells exacerbates macrophage responses to acute bacterial infection in mice, leading to high mortality due to sustained production of pro-inflammatory cytokines. METTL14 depletion blunts Socs1 m6A methylation and reduces YTHDF1 binding to the m6A sites, which diminishes SOCS1 induction leading to the overactivation of TLR4/NF-κB signaling. Forced expression of SOCS1 in macrophages depleted of METTL14 or YTHDF1 rescues the hyper-responsive phenotype of these macrophages in vitro and in vivo. We further show that LPS treatment induces Socs1 m6A methylation and sustains SOCS1 induction by promoting Fto mRNA degradation, and forced FTO expression in macrophages mimics the phenotype of METTL14-depleted macrophages. We conclude that m6A methylation-mediated SOCS1 induction is required to maintain the negative feedback control of macrophage activation in response to bacterial infection.

Vitamin D/VDR signaling induces miR-27a/b expression in oral lichen planus.

MicroRNA-27a/b are small non-coding RNAs which are reported to regulate inflammatory response and cell proliferation. Although some studies have demonstrated that miR-27b is down-regulated in the oral specimens of patients suffering with oral lichen planus (OLP), the molecular mechanism of miR-27b decrease remains a large mystery, and the expression of miR-27a in OLP is not well explored. Here, we demonstrated both miR-27a and miR-27b, compared with healthy controls, were reduced in the oral biopsies, serum and saliva samples derived from OLP patients. The reductions of miR-27a/b were also confirmed in the lipopolysaccharide (LPS)- or activated CD4+ T cell-treated human oral keratinocytes (HOKs). Furthermore, we found vitamin D receptor (VDR) binding sites in the promoters of miR-27a/b genes and verified this finding. We also tested miR-27a/b levels in the oral epithelium from paricalcitol-treated, vitamin D deficient or VDR knockout mice. In the rescue experiments, we confirmed vitamin D and VDR inhibited LPS- or activated CD4+ T cell-induced miR-27a/b reductions in HOKs. In sum, our results show that vitamin D/VDR signaling induces miR-27a/b in oral lichen planus.

MicroRNA-26a/b have protective roles in oral lichen planus.

Oral lichen planus (OLP) is a kind of oral epithelial disorder featured with keratinocyte apoptosis and inflammatory reaction. The pathogenesis of OLP remains an enigma. Herein, we showed that the levels of miR-26a/b were robustly down-regulated in oral mucosal biopsies, serum and saliva in OLP patients compared with healthy control. Moreover, we found the binding sites of vitamin D receptor (VDR) in the promoter regions of miR-26a/b genes and proved that the induction of miR-26a/b was VDR dependent. The reduction of miR-26a/b expression was also detected in the oral epithelium of vitamin D deficient or VDR knockout mice. miR-26a/b inhibitors enhanced apoptosis and Type 1T helper (Th1) cells-related cytokines production in oral keratinocytes, whereas miR-26a/b mimics were protective. Mechanistically, we analyzed miRNA target genes and confirmed that miR-26a/b blocked apoptosis by directly targeting Protein Kinase C δ (PKCδ) which promotes cellular apoptotic processes. Meanwhile, miR-26a/b suppressed Th1-related cytokines secretion through targeting cluster of the differentiation 38 (CD38). In accordant with miR-26a/b decreases, PKCδ and CD38 levels were highly elevated in OLP patients' samples. Taken together, our present investigations suggest that vitamin D/VDR-induced miR-26a/b take protective functions in OLP via both inhibiting apoptosis and impeding inflammatory response in oral keratinocytes.