Dysregulated Cholesterol Metabolism Research Articles

Tumor-derived miR-9-5p-loaded EVs regulate cholesterol homeostasis to promote breast cancer liver metastasis in mice

Cancer cells secrete extracellular vesicles (EV) encapsulating bioactive cargoes to facilitate inter-organ communication in vivo and are emerging as critical mediators of tumor progression and metastasis, a condition which is often accompanied by a dysregulated cholesterol metabolism. Whether EVs are involved in the control of cholesterol homeostasis during tumor metastasis is still undefined and warrant further investigation. Here, we find that breast cancer-derived exosomal miR-9-5p induces the expression of HMGCR and CH25H, two enzymes involved in cholesterol synthesis and the conversion of 25-hydroxycholesterol from cholesterol by targeting INSIG1, INSIG2 and ATF3 genes in the liver. Notably, in vivo miR-9-5p antagomir treatment and genetic CH25H ablation prevents tumor metastasis in a mouse model of breast cancer. Thus, our findings reveal the regulatory mechanism of tumor-derived miR-9-5p in liver metastasis by linking oxysterol metabolism and Kupffer cell polarization, shedding light on future applications for cancer diagnosis and treatment.

Cupric Doping Hollow Prussian Blue Nanoplatform for Enhanced Cholesterol Depletion: a Promising Strategy for Breast Cancer Therapy and Metastasis Inhibition.

The dysregulated cholesterol metabolism in breast cancer cells drives malignancy, invasion, and metastasis, emphasizing the significance of reducing abnormal cholesterol accumulation for effective cancer treatment and metastasis inhibition. Despite its promise, cholesterol oxidase (ChOx) encounters challenge due to limited catalytic efficiency and susceptibility to harsh conditions. To overcome these hurdles, biocompatible nanoplatforms (Cu-HPB/C) tailored for efficient cholesterol depletion are introduced. Cu2+-doped hollow Prussian blue (Cu-HPB) acts as a carrier, shelter, and enhancer for ChOx, bolstering tumor-targeting ability, stability, and enzymatic activity. Tumor-responsive released Cu2+ notably augments ChOx activity, facilitating cholesterol depletion and disrupting lipid rafts, thereby impeding cell invasion and migration. Additionally, H2O2 generated from the oxidase reaction enhances Cu-HPB's chemo dynamic therapeutic efficacy. Transcriptomic analysis validates Cu-HPB/C's impact on cholesterol homeostasis and reveals cell death mechanisms including oxidative stress, ferroptosis, cuproptosis, and apoptosis. Demonstrating therapeutic efficacy in both 4T1 tumor subcutaneous and metastasis mouse models, the study presents a direct and effective strategy for tumor therapy and metastasis inhibition through enhanced cholesterol depletion.

Microglia States are Susceptible to Senescence and Cholesterol Dysregulation in Alzheimer's Disease.

Cellular senescence is a major contributor to aging-related degenerative diseases, including Alzheimer's disease (AD) but much less is known on the key cell types and pathways driving mechanisms of senescence in the brain. We hypothesized that dysregulated cholesterol metabolism is central to cellular senescence in AD. We analyzed whole transcriptomic data and utilized single-cell RNA seq integration techniques to unveil the convoluted cell-type-specific and sub-cell-type-state-specific senescence pathologies in AD using both ROSMAP and Sea-AD datasets. We identified that microglia are central components to AD associated senescence phenotypes in ROSMAP snRNA-seq data (982,384 nuclei from postmortem prefrontal cortex of 239 AD and 188 non-AD) among non-neuron cell types. We identified that homeostatic, inflammatory, phagocytic, lipid processing and neuronal surveillance microglia states were associated with AD associated senescence in ROSMAP (152,459 microglia nuclei from six regions of brain tissue of 138 early AD, 79 late AD and 226 control subject) and in Sea-AD (82,486 microglia nuclei of 42 dementia, 42 no dementia and 5 reference subjects) via integrative analysis, which preserves the meaningful biological information of microglia cell states across the datasets. We assessed top senescence associated bioprocesses including mitochondrial, apoptosis, oxidative stress, ER stress, endosomes, and lysosomes systems. Specifically, we found that senescent microglia have altered cholesterol related bioprocesses and dysregulated cholesterol. We discovered three gene co-expression modules, which represent the specific cholesterol related senescence transcriptomic signatures in postmortem brains. To validate these findings, the activation of specific cholesterol associated senescence transcriptomic signatures was assessed using integrative analysis of snRNA-seq data from iMGs (microglia induced from iPSCs) exposed to myelin, Abeta, and synaptosomes (56,454 microglia across two replicates of untreated and four treated groups). In vivo cholesterol associated senescence transcriptomic signatures were preserved and altered after treatment with AD pathological substrates in iMGs. This study provides the first evidence that dysregulation of cholesterol metabolism in microglia is a major driver of senescence pathologies in AD. Targeting cholesterol pathways in senescent microglia is an attractive strategy to slow down AD progression.

Cosmc regulates O-glycan extension in murine hepatocytes.

Hepatocytes synthesize a vast number of glycoproteins found in their membranes and secretions, many of which contain O-glycans linked to Ser/Thr residues. As the functions and distribution of O-glycans on hepatocyte-derived membrane glycoproteins and blood glycoproteins are not well understood, we generated mice with a targeted deletion of Cosmc (C1Galt1c1) in hepatocytes. Liver glycoproteins in WT mice express typical sialylated core 1 O-glycans (T antigen/CD176) (Galβ1-3GalNAcα1-O-Ser/Thr), whereas the Cosmc knockout hepatocytes (HEP-Cosmc-KO) lack extended O-glycans and express the Tn antigen (CD175) (GalNAcα1-O-Ser/Thr). Tn-containing glycoproteins occur in the sera of HEP-Cosmc-KO mice but not in WT mice. The LDL-receptor (LDLR), a well-studied O-glycosylated glycoprotein in hepatocytes, behaves as a ∼145kD glycoprotein in WT liver lysates, whereas it is reduced to ∼120kDa in lysates from HEP-Cosmc-KO mice. Interestingly, the expression of the LDLR, as well as HMG-CoA reductase, which is typically altered in response to dysregulated cholesterol metabolism, are similar between WT and HEP-Cosmc-KO mice, indicating no significant effect by Cosmc deletion on either LDLR stability or cholesterol metabolism. Consistent with this, we observed no detectable phenotype in the HEP-Cosmc-KO mice regarding development, appearance or aging compared to WT. These results provide surprising, novel information about the pathway of O-glycosylation in the liver.

Cholesterol Accumulation Promotes Photoreceptor Senescence and Retinal Degeneration.

Dysregulated cholesterol metabolism is critical in the pathogenesis of AMD. Cellular senescence contributes to the development of numerous age-associated diseases. In this study, we investigated the link between cholesterol burden and the cellular senescence of photoreceptors. Retinas from rod-specific ATP binding cassette subfamily A member 1 (Abca1) and G member 1 (Abcg1) (Abca1/g1-rod/-rod) knockout mice fed with a high-fat diet were analyzed for the signs of cellular senescence. Real-time quantitative PCR and immunofluorescence were used to characterize the senescence profile of the retina and cholesterol-treated photoreceptor cell line (661W). Inducible elimination of p16(Ink4a)-positive senescent cells (INK-ATTAC) mice or the administration of senolytic drugs (dasatinib and quercetin: D&Q) were used to examine the impact of senolytics on AMD-like phenotypes in Abca1/g1-rod/-rod retina. Increased accumulation of senescent cells as measured by markers of cellular senescence was found in Abca1/g1-rod/-rod retina. Exogenous cholesterol also induced cellular senescence in 661W cells. Selective elimination of senescent cells in Abca1/g1-rod/-rod;INK-ATTAC mice or by administration of D&Q improved visual function, lipid accumulation in retinal pigment epithelium, and Bruch's membrane thickening. Cholesterol accumulation promotes cellular senescence in photoreceptors. Eliminating senescent photoreceptors improves visual function in a model of retinal neurodegeneration, and senotherapy offers a novel therapeutic avenue for further investigation.

Escalation of Actions of Endocrine Networks for Treating Triple Negative Breast Cancer with Greater Efficacy: A Narrative Review

Earlier we had reviewed the detailed etiopathogenesis, treatment of BC,besidesupdate on management of triple negative breast cancer(TNBC) along with how dysregulated cholesterol metabolism including oxysterolswere implicated in the pathophysiology of breast cancer along with use that pathway for treating it,apart from ’using tocopherols/ phytosterols derived from Pequi(Caryocar brasiliansis Camb.) for complementing chemotherapy for BC treatment/alone or as new herbal therapy for improving 5year survival, and part of syndecans in pathogenesis&detailed Selective estrogen receptors modulators(SERM) & Selective estrogen receptors degraders(SERD’s)in avoiding post menopausal fractures &for BC therapy,As per the immunohistochemical categorized estrogen/ progesterone(P4) receptors decide the endocrine plausibility of the course of treatment of breast cancer. Possessing the properties of deficiency of estrogen receptor α,ERα negative breast cancer become detached from any kinds of endocrine regimens as far as the clinical scenario is concerned in routine specificallyin case of TNBC . Nevertheless, this paradigm got challenges by the fact that triple negative breast cancers continued to possess retention of sensitivity along with susceptibility to endocrine substances. The crosstalking of hormone effects program earlier unappreaciated was over time realized in addition to carcinogenic signaling, which were escalatingly examined.Correspondingly,the previously ignored endocrine reactiveness in ERα negative breast cancers garnered interest providing innovative therapeutic approach in an ERα independent manner.Here we summarize the genomic in addition to non genomic steroid hormone effects along with endocrine correlated signals in TNBC, accompanied by the tag of hormone insensitivity. Moreover, insight is provided over non classical mechanistic modes determined in usual hormone substances for illustrating their pleiotropic actions .Further we highlighted how modulating gut microbiota(GM)might enhance these actions.

LXR/CD38 activation drives cholesterol-induced macrophage senescence and neurodegeneration via NAD+ depletion

Although dysregulated cholesterol metabolism predisposes aging tissues to inflammation and a plethora of diseases, the underlying molecular mechanism remains poorly defined. Here, we show that metabolic and genotoxic stresses, convergently acting through liver X nuclear receptor, upregulate CD38 to promote lysosomal cholesterol efflux, leading to nicotinamide adenine dinucleotide (NAD+) depletion in macrophages. Cholesterol-mediated NAD+ depletion induces macrophage senescence, promoting key features of age-related macular degeneration (AMD), including subretinal lipid deposition and neurodegeneration. NAD+ augmentation reverses cellular senescence and macrophage dysfunction, preventing the development of AMD phenotype. Genetic and pharmacological senolysis protect against the development of AMD and neurodegeneration. Subretinal administration of healthy macrophages promotes the clearance of senescent macrophages, reversing the AMD disease burden. Thus, NAD+ deficit induced by excess intracellular cholesterol is the converging mechanism of macrophage senescence and a causal process underlying age-related neurodegeneration.

Oncolytic adenovirus encoding apolipoprotein A1 suppresses metastasis of triple-negative breast cancer in mice

BackgroundDysregulation of cholesterol metabolism is associated with the metastasis of triple-negative breast cancer (TNBC). Apolipoprotein A1 (ApoA1) is widely recognized for its pivotal role in regulating cholesterol efflux and maintaining cellular cholesterol homeostasis. However, further exploration is needed to determine whether it inhibits TNBC metastasis by affecting cholesterol metabolism. Additionally, it is necessary to investigate whether ApoA1-based oncolytic virus therapy can be used to treat TNBC.MethodsIn vitro experiments and mouse breast cancer models were utilized to evaluate the molecular mechanism of ApoA1 in regulating cholesterol efflux and inhibiting breast cancer progression and metastasis. The gene encoding ApoA1 was inserted into the adenovirus genome to construct a recombinant adenovirus (ADV-ApoA1). Subsequently, the efficacy of ADV-ApoA1 in inhibiting the growth and metastasis of TNBC was evaluated in several mouse models, including orthotopic breast cancer, spontaneous breast cancer, and human xenografts. In addition, a comprehensive safety assessment of Syrian hamsters and rhesus monkeys injected with oncolytic adenovirus was conducted.ResultsThis study found that dysregulation of cholesterol homeostasis is critical for the progression and metastasis of TNBC. In a mouse orthotopic model of TNBC, a high-cholesterol diet promoted lung and liver metastasis, which was associated with keratin 14 (KRT14), a protein responsible for TNBC metastasis. Furthermore, studies have shown that ApoA1, a cholesterol reverse transporter, inhibits TNBC metastasis by regulating the cholesterol/IKBKB/FOXO3a/KRT14 axis. Moreover, ADV-ApoA1 was found to promote cholesterol efflux, inhibit tumor growth, reduce lung metastasis, and prolonged the survival of mice with TNBC. Importantly, high doses of ADV-ApoA1 administered intravenously and subcutaneously were well tolerated in rhesus monkeys and Syrian hamsters.ConclusionsThis study provides a promising oncolytic virus treatment strategy for TNBC based on targeting dysregulated cholesterol metabolism. It also establishes a basis for subsequent clinical trials of ADV-ApoA1 in the treatment of TNBC.

Impaired oxysterol-liver X receptor signaling underlies aberrant cortical neurogenesis in a stem cell model of neurodevelopmental disorder

The mechanisms by which genomic risks contribute to the onset of neuropsychiatric conditions remain a key challenge and a prerequisite for successful development of effective therapies. 15q11.2 copy number variation (CNV) containing the CYFIP1 gene is associated with autism and schizophrenia. Using stem cell models, we show that 15q11.2 deletion (15q11.2del) and CYFIP1 loss of function (CYFIP1-LoF) lead to premature neuronal differentiation, while CYFIP1 gain of function (CYFIP1-GoF) favors neural progenitor maintenance. CYFIP1 dosage changes led to dysregulated cholesterol metabolism and altered levels of 24S,25-epoxycholesterol, which can mimic the 15q11.2del and CYFIP1-LoF phenotypes by promoting cortical neuronal differentiation and can restore the impaired neuronal differentiation of CYFIP1-GoF neural progenitors. Moreover, the neurogenic activity of 24S,25-epoxycholesterol is lost following genetic deletion of liver X receptor (LXRβ), while compound deletion of LXRβ in CYFIP1-/- background rescued their premature neurogenesis. This work delineates LXR-mediated oxysterol regulation of neurogenesis as a pathological mechanism in neural cells carrying 15q11.2 CNV and provides a potential target for therapeutic strategies for associated disorders.

Alterations of the chemical profile of cholesterol in cancer tissue as traced with ToF-SIMS.

Cancer has become one of the leading causes of death, with approximately ten million people worldwide dying from cancer each year. In most cases, cancer spreads to remote organs and develops a resistance to therapy. To reduce the deadly impact of cancer, novel targets for markers for early detection are necessary. Given the notable influence of rapid chemical turnover on isotope effects, the heightened turnover rate of cholesterol in cancer offers a promising way for investigation. Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) offers a valuable tool of tracking cholesterol dynamics. Consequently, we employed ToF-SIMS to assess cholesterol alterations, aiming to uncover potential diagnostic vulnerabilities stemming from heightened cholesterol synthesis. Our study explored the chemical profile of cholesterol influenced by cancer cell metabolism using mammary glands from mice, both with and without cancer. Results revealed a significant increase in the fractional abundance of fragment cholesterol peaks (C27H45+) in cancerous tissues, indicating dysregulated cholesterol metabolism within cancer cells. This suggests potential structural weaknesses or incomplete synthesis. Further investigation into carbon isotope incorporation suggests that the isotopic patterns might be due to the integration of heavier carbon isotopes, although these patterns could be affected by other isotopic influences. Nevertheless, understanding isotope effect of cholesterol profiles have the potential to advance our understanding of cancer biology and improve diagnostic approaches.

Intracavitary Spraying of Nanoregulator-Encased Hydrogel Modulates Cholesterol Metabolism of Glioma-Supportive Macrophage for Postoperative Glioblastoma Immunotherapy.

Glioblastoma multiforme (GBM) is notoriously resistant to immunotherapy due to its intricate immunosuppressive tumor microenvironment (TME). Dysregulated cholesterol metabolism is implicated in the TME and promotes tumor progression. Here, it is found that cholesterol levels in GBM tissues are abnormally high, and glioma-supportive macrophages (GSMs), an essential "cholesterol factory", demonstrate aberrantly hyperactive cholesterol metabolism and efflux, providing cholesterol to fuel GBM growth and induce CD8+ T cells exhaustion. Bioinformatics analysis confirms that high 7-dehydrocholesterol reductase (DHCR7) level in GBM tissues associates with increased cholesterol biosynthesis, suppressed tumoricidal immune response, and poor patient survival, and DHCR7 expression level is significantly elevated in GSMs. Therefore, an intracavitary sprayable nanoregulator (NR)-encased hydrogel system to modulate cholesterol metabolism of GSMs is reported. The degradable NR-mediated ablation of DHCR7 in GSMs effectively suppresses cholesterol supply and activates T-cell immunity. Moreover, the combination of Toll-like receptor 7/8 (TLR7/8) agonists significantly promotes GSM polarization to antitumor phenotypes and ameliorates the TME. Treatment with the hybrid system exhibits superior antitumor effects in the orthotopic GBM model and postsurgical recurrence model. Altogether, the findings unravel the role of GSMs DHCR7/cholesterol signaling in the regulation of TME, presenting a potential treatment strategy that warrants further clinical trials.

TRENDS IN CHOLESTEROL AND LIPOPROTEINS ARE ASSOCIATED WITH ACUTE RESPIRATORY DISTRESS SYNDROME INCIDENCE AND DEATH AMONG SEPSIS PATIENTS.

Objective: Compare changes in cholesterol and lipoprotein levels occurring in septic patients with and without acute respiratory distress syndrome (ARDS) and by survivorship. Methods: We reanalyzed data from prospective sepsis studies. Cholesterol and lipoprotein levels were analyzed using univariate testing to detect changes between septic patients with or without ARDS, and among ARDS survivors compared with nonsurvivors at enrollment (first 24 h of sepsis) and 48 to 72 h later. Results: 214 patients with sepsis were included of whom 48 had ARDS and 166 did not have ARDS. Cholesterol and lipoproteins among septic ARDS versus non-ARDS showed similar enrollment levels. However, 48 to 72 h after enrollment, change in median total cholesterol (48/72 h - enrollment) was significantly different between septic ARDS (-4, interquartile range [IQR] -23.5, 6.5, n = 35) and non-ARDS (0, -10.0, 17.5, P = 0.04; n = 106). When compared by ARDS survivorship, ARDS nonsurvivors (n = 14) had lower median total cholesterol levels (75.5, IQR 68.4, 93.5) compared with ARDS survivors (113.0, IQR 84.0, 126.8, P = 0.022), and lower median enrollment low-density lipoprotein cholesterol (LDL-C) levels (27, IQR 19.5-34.5) compared with ARDS survivors (43, IQR 27-67, P = 0.013; n = 33). Apolipoprotein A-I levels were also significantly lower in ARDS nonsurvivors (n = 14) (87.6, IQR 76.45-103.64) compared with ARDS survivors (130.0, IQR 73.25-165.47, P = 0.047; n = 33). At 48 to 72 h, for ARDS nonsurvivors, median levels of low-density lipoprotein cholesterol (9.0, IQR 4.3, 18.0; n = 10), LDL-C (17.0, IQR 5.0, 29.0; n = 9), and total cholesterol (59.0, 45.3, 81.5; n = 10) were significantly lower compared with ARDS survivors' (n = 25) levels of low-density lipoprotein cholesterol (20.0, IQR 12.0-39.0, P = 0.014), LDL-C (42.0, IQR 27.0-58.0, P = 0.019), and total cholesterol (105.0, IQR 91.0, 115.0, P = 0.003). Conclusions: Change in total cholesterol was different in septic ARDS versus non-ARDS. Total cholesterol, LDL-C, and apolipoprotein A-I levels were lower in ARDS nonsurvivors compared with survivors. Future studies of dysregulated cholesterol metabolism in septic ARDS patients are needed to understand biology and links to potential therapies.

Cholesterol deficiency as a mechanism for autism: A valproic acid model.

Dysregulated cholesterol metabolism represents an increasingly recognized feature of autism spectrum disorder (ASD). Children with fetal valproate syndrome caused by prenatal exposure to valproic acid (VPA), an anti-epileptic and mood-stabilizing drug, have a higher incidence of developing ASD. However, the role of VPA in cholesterol homeostasis in neurons and microglial cells remains unclear. Therefore, we examined the effect of VPA exposure on regulation of cholesterol homeostasis in the human microglial clone 3 (HMC3) cell line and the human neuroblastoma cell line SH-SY5Y. HMC3 and SH-SY5Y cells were each incubated in increasing concentrations of VPA, followed by quantification of mRNA and protein expression of cholesterol transporters and cholesterol metabolizing enzymes. Cholesterol efflux was evaluated using colorimetric assays. We found that VPA treatment in HMC3 cells significantly reduced ABCA1 mRNA, but increased ABCG1 and CD36 mRNA levels in a dose-dependent manner. However, ABCA1 and ABCG1 protein levels were reduced by VPA in HMC3. Furthermore, similar experiments in SH-SY5Y cells showed increased mRNA levels for ABCA1, ABCG1, CD36, and 27-hydroxylase with VPA treatment. VPA exposure significantly reduced protein levels of ABCA1 in a dose-dependent manner, but increased the ABCG1 protein level at the highest dose in SH-SY5Y cells. In addition, VPA treatment significantly increased cholesterol efflux in SH-SY5Y, but had no impact on efflux in HMC3. VPA differentially controls the expression of ABCA1 and ABCG1, but regulation at the transcriptional and translational levels are not consistent and changes in the expression of these genes do not correlate with cholesterol efflux in vitro.

Identification of a cholesterol metabolism-related prognostic signature for multiple myeloma

Multiple myeloma (MM) is a prevalent hematological malignancy that poses significant challenges for treatment. Dysregulated cholesterol metabolism has been linked to tumorigenesis, disease progression, and therapy resistance. However, the correlation between cholesterol metabolism-related genes (CMGs) and the prognosis of MM remains unclear. Univariate Cox regression analysis and LASSO Cox regression analysis were applied to construct an overall survival-related signature based on the Gene Expression Omnibus database. The signature was validated using three external datasets. Enrichment analysis and immune analysis were performed between two risk groups. Furthermore, an optimal nomogram was established for clinical application, and its performance was assessed by the calibration curve and C-index. A total of 6 CMGs were selected to establish the prognostic signature, including ANXA2, CHKA, NSDHL, PMVK, SCAP and SQLE. The prognostic signature demonstrated good prognostic performance and correlated with several important clinical parameters, including number of transplants, International Staging System, albumin, beta2-Microglobulin and lactate dehydrogenase levels. The function analysis and immune analysis revealed that the metabolic pathways and immunologic status were associated with risk score. The nomogram incorporating the signature along with other clinical characteristics was constructed and the discrimination was verified by the calibration curve and C-index. Our findings indicated the potential prognostic connotation of cholesterol metabolism in MM. The development and validation of the prognostic signature is expected to aid in predicting prognosis and guiding precision treatment for MM.

Side-Chain Immune Oxysterols Induce Neuroinflammation by Activating Microglia.

In individuals with Alzheimer's disease, the brain exhibits elevated levels of IL-1β and oxygenated cholesterol molecules (oxysterols). This study aimed to investigate the effects of side-chain oxysterols on IL-1β expression using HMC3 microglial cells and ApoE-deficient mice. Treatment of HMC3 cells with 25-hydroxycholesterol (25OHChol) and 27-hydroxycholesterol (27OHChol) led to increased IL-1β expression at the transcript and protein levels. Additionally, these oxysterols upregulated the surface expression of MHC II, a marker of activated microglia. Immunohistochemistry performed on the mice showed increased microglial expression of IL-1β and MHC II when fed a high-cholesterol diet. However, cholesterol and 24s-hydroxycholesterol did not increase IL-1β transcript levels or MHC II expression. The extent of IL-1β increase induced by 25OHChol and 27OHChol was comparable to that caused by oligomeric β-amyloid, and the IL-1β expression induced by the oxysterols was not impaired by polymyxin B, which inhibited lipopolysaccharide-induced IL-1β expression. Both oxysterols enhanced the phosphorylation of Akt, ERK, and Src, and inhibition of these kinase pathways with pharmacological inhibitors suppressed the expression of IL-1β and MHC II. The pharmacological agents chlorpromazine and cyclosporin A also impaired the oxysterol-induced expression of IL-1β and upregulation of MHC II. Overall, these findings suggest that dysregulated cholesterol metabolism leading to elevated levels of side-chain oxysterols, such as 25OHChol and 27OHChol, can activate microglia to secrete IL-1β through a mechanism amenable to pharmacologic intervention. The activation of microglia and subsequent neuroinflammation elicited by the immune oxysterols can contribute to the development of neurodegenerative diseases.

Bridging the gap between clear cell renal cell carcinoma and cutaneous melanoma: the role of SCARB1 in dysregulated cholesterol metabolism.

The metabolism of cholesterol has been found to be closely related to the proliferation, invasion, and metastasis of tumors. The purpose of this study was to investigate the correlation between cholesterol metabolic genes and the prognosis of clear cell renal cell carcinoma (ccRCC). Gene expression profiles and clinical information of individuals diagnosed with prevalent malignant tumors were obtained from the TCGA database. For survival analysis, Kaplan-Meier curves were used. Consensus clustering was utilized to identify distinct molecular clusters. LASSO regression analysis was utilized to construct a novel prognostic signature. Differential analysis was used to analyze the differences in gene expression and various evaluation indicators between different subgroups. RT-qPCR and Immunohistochemistry were performed to examine the gene expression. Small interfering RNA transfection, CCK-8, and clone formation assays were conducted to verify the function of the target gene in ccRCC cell lines. Based on genes involved in cholesterol metabolism related to survival, two molecular ccRCC subtypes were identified with distinct clinical, immune, and biological features. A molecular signature which would be utilized to evaluate the prognosis and the immune status of the tumor microenvironment of ccRCC patients was also established. The SCARB1-mediated cholesterol-dependent metabolism occurred both in ccRCC and skin cutaneous melanoma. A gene signature related to cholesterol metabolism was developed and validated to forecast the prognosis of ccRCC, demonstrating a correlation with immune infiltration. Cholesterol metabolic genes such as SCARB1, were expected to contribute to the diagnosis and precision treatment of both ccRCC and skin cutaneous melanoma.

Lysosomal cholesterol overload in macrophages promotes liver fibrosis in a mouse model of NASH.

Accumulation of lipotoxic lipids, such as free cholesterol, induces hepatocyte death and subsequent inflammation and fibrosis in the pathogenesis of nonalcoholic steatohepatitis (NASH). However, the underlying mechanisms remain unclear. We have previously reported that hepatocyte death locally induces phenotypic changes in the macrophages surrounding the corpse and remnant lipids, thereby promoting liver fibrosis in a murine model of NASH. Here, we demonstrated that lysosomal cholesterol overload triggers lysosomal dysfunction and profibrotic activation of macrophages during the development of NASH. β-cyclodextrin polyrotaxane (βCD-PRX), a unique supramolecule, is designed to elicit free cholesterol from lysosomes. Treatment with βCD-PRX ameliorated cholesterol accumulation and profibrotic activation of macrophages surrounding dead hepatocytes with cholesterol crystals, thereby suppressing liver fibrosis in a NASH model, without affecting the hepatic cholesterol levels. In vitro experiments revealed that cholesterol-induced lysosomal stress triggered profibrotic activation in macrophages predisposed to the steatotic microenvironment. This study provides evidence that dysregulated cholesterol metabolism in macrophages would be a novel mechanism of NASH.

Hepatic steatosis is associated with dysregulated cholesterol metabolism and altered protein acetylation dynamics in chickens

BackgroundHepatic steatosis is a prevalent manifestation of fatty liver, that has detrimental effect on the health and productivity of laying hens, resulting in economic losses to the poultry industry. Here, we aimed to systematically investigate the genetic regulatory mechanisms of hepatic steatosis in laying hens.MethodsNinety individuals with the most prominent characteristics were selected from 686 laying hens according to the accumulation of lipid droplets in the liver, and were graded into three groups, including the control, mild hepatic steatosis and severe hepatic steatosis groups. A combination of transcriptome, proteome, acetylome and lipidome analyses, along with bioinformatics analysis were used to screen the key biological processes, modifications and lipids associated with hepatic steatosis.ResultsThe rationality of the hepatic steatosis grouping was verified through liver biochemical assays and RNA-seq. Hepatic steatosis was characterized by increased lipid deposition and multiple metabolic abnormalities. Integration of proteome and acetylome revealed that differentially expressed proteins (DEPs) interacted with differentially acetylated proteins (DAPs) and were involved in maintaining the metabolic balance in the liver. Acetylation alterations mainly occurred in the progression from mild to severe hepatic steatosis, i.e., the enzymes in the fatty acid oxidation and bile acid synthesis pathways were significantly less acetylated in severe hepatic steatosis group than that in mild group (P < 0.05). Lipidomics detected a variety of sphingolipids (SPs) and glycerophospholipids (GPs) were negatively correlated with hepatic steatosis (r ≤ −0.5, P < 0.05). Furthermore, the severity of hepatic steatosis was associated with a decrease in cholesterol and bile acid synthesis and an increase in exogenous cholesterol transport.ConclusionsIn addition to acquiring a global and thorough picture of hepatic steatosis in laying hens, we were able to reveal the role of acetylation in hepatic steatosis and depict the changes in hepatic cholesterol metabolism. The findings provides a wealth of information to facilitate a deeper understanding of the pathophysiology of fatty liver and contributes to the development of therapeutic strategies.

Impaired Cholesterol Metabolism, Neurons, and Neuropsychiatric Disorders

Cholesterol metabolism plays an essential role in cellular functions (including as a component of the plasma membrane, as an energy source, and in hormone production) under normal conditions. Dysregulated cholesterol metabolism causes a wide spectrum of pathological conditions, leading to neuropsychiatric disorders, such as anxiety and depression. In addition, patients with neuropsychiatric disorders also have impaired cholesterol metabolism. Therefore, metabolic disturbances are closely associated with the neuropsychiatric disorders. Although immune disturbance, neuroinflammation, a dysregulated neurotransmitter system, and oxidative stress have been suggested as pathophysiology of neuropsychiatric disorders, dysregulation of cholesterol metabolism is also found in patients with psychiatric diseases. As expected, patients with mental illness appear to be at risk of metabolic disorders, including metabolic syndrome, in which cholesterol influences altered neuronal homeostasis, such as neuronal cell toxicity, neuronal cell death, and neuronal structures and functions, including synaptogenesis, neurogenesis, axonogenesis, and action potential. Therefore, reversing impaired or abnormal cholesterol metabolism may help restore neuronal injury found in mental illness. This review is aimed to discuss the links between cholesterol metabolism impairment and neuropsychiatric disorders and provides insights into neuronal dysfunction due to abnormal cholesterol metabolism in neuropsychiatric disorders.

Regulation of astrocyte lipid metabolism and ApoE secretion by the microglial oxysterol, 25-hydroxycholesterol

Neuroinflammation, a major hallmark of Alzheimer’s disease and several other neurological and psychiatric disorders, is often associated with dysregulated cholesterol metabolism. Relative to homeostatic microglia, activated microglia express higher levels of Ch25h, an enzyme that hydroxylates cholesterol to produce 25-hydroxycholesterol (25HC). 25HC is an oxysterol with interesting immune roles stemming from its ability to regulate cholesterol metabolism. Since astrocytes synthesize cholesterol in the brain and transport it to other cells via ApoE-containing lipoproteins, we hypothesized that secreted 25HC from microglia may influence lipid metabolism as well as extracellular ApoE derived from astrocytes. Here, we show that astrocytes take up externally added 25HC and respond with altered lipid metabolism. Extracellular levels of ApoE lipoprotein particles increased after treatment of astrocytes with 25HC without an increase in Apoe mRNA expression. In mouse astrocytes-expressing human ApoE3 or ApoE4, 25HC promoted extracellular ApoE3 better than ApoE4. Increased extracellular ApoE was due to elevated efflux from increased Abca1 expression via LXRs as well as decreased lipoprotein reuptake from suppressed Ldlr expression via inhibition of SREBP. 25HC also suppressed expression of Srebf2, but not Srebf1, leading to reduced cholesterol synthesis in astrocytes without affecting fatty acid levels. We further show that 25HC promoted the activity of sterol-o-acyl transferase that led to a doubling of the amount of cholesteryl esters and their concomitant storage in lipid droplets. Our results demonstrate an important role for 25HC in regulating astrocyte lipid metabolism.