Low-density Lipoprotein Receptor-related Protein Research Articles

Contribution of LRP1 in Human Congenital Heart Disease Correlates with Its Roles in the Outflow Tract and Atrioventricular Cushion Development.

Due to the prevalence of congenital heart disease in the human population, determining the role of variants in congenital heart disease (CHD) can give a better understanding of the cause of the disorder. A homozygous missense mutation in the LDL receptor-related protein 1 (Lrp1) in mice was shown to cause congenital heart defects, including atrioventricular septal defect (AVSD) and double outlet right ventricle (DORV). Integrative analysis of publicly available single-cell RNA sequencing (scRNA-seq) datasets and spatial transcriptomics of human and mouse hearts indicated that LRP1 is predominantly expressed in mesenchymal cells and mainly located in the developing outflow tract and atrioventricular cushion. Gene burden analysis of 1922 CHD individuals versus 2602 controls with whole-exome sequencing showed a significant excess of rare damaging LRP1 mutations in CHD (odds ratio (OR) = 2.22, p = 1.92 × 10-4), especially in conotruncal defect with OR of 2.37 (p = 1.77 × 10-3) and atrioventricular septal defect with OR of 3.14 (p = 0.0194). Interestingly, there is a significant relationship between those variants that have an allele frequency below 0.01% and atrioventricular septal defect, which is the phenotype observed previously in a homozygous N-ethyl-N-nitrosourea (ENU)-induced Lrp1 mutant mouse line.

LDL receptor related protein 1 is an adverse prognostic biomarker that correlates with stromal remodeling and macrophages infiltration in bladder cancer.

Bladder cancer (BLCA) is a highly heterogeneous disease influenced by the tumor microenvironment, which may affect patients' response to immune checkpoint blockade therapy. Therefore, identifying molecular markers and therapeutic targets to improve treatment is essential. In this study, we aimed to investigate the prognostic significance of LRP1 in BLCA. We analyzed TCGA and IMvigor210 cohorts to investigate the relationship of LRP1 with BLCA prognosis. We utilized gene mutation analysis and enrichment to identify LRP1-associated mutated genes and biological processes. Deconvolution algorithms and single-cell analysis were used to understand the tumor-infiltrated cells and biological pathways associated with LRP1 expression. Immunohistochemistry was conducted to validate the bioinformatics analysis. Our study revealed that LRP1 was an independent risk factor for overall survival in BLCA patients and was associated with clinicopathological features and FGFR3 mutation frequency. Enrichment analysis demonstrated that LRP1 was involved in extracellular matrix remodeling and tumor metabolic processes. Furthermore, the ssGSEA algorithm revealed that LRP1 was positively correlated with the activities of tumor-associated pathways. Our study also found that high LRP1 expression impaired patients' responsiveness to ICB therapy in BLCA, which was predicted by TIDE prediction and validated by IMvigor210 cohort. Immunohistochemistry confirmed the expression of LRP1 in Cancer-Associated Fibroblasts (CAFs) and macrophages in the tumor microenvironment of BLCA. Our study suggests that LRP1 may be a potential prognostic biomarker and therapeutic target in BLCA. Further research on LRP1 may improve BLCA precision medicine and enhance the efficacy of immune checkpoint blockade therapy.

Low-density lipoprotein receptor-related protein 1 (LRP1) as an auxiliary host factor for RNA viruses.

Viruses with an RNA genome are often the cause of zoonotic infections. In order to identify novel pro-viral host cell factors, we screened a haploid insertion-mutagenized mouse embryonic cell library for clones that are resistant to Rift Valley fever virus (RVFV). This screen returned the low-density lipoprotein receptor-related protein 1 (LRP1) as a top hit, a plasma membrane protein involved in a wide variety of cell activities. Inactivation of LRP1 in human cells reduced RVFV RNA levels already at the attachment and entry stages of infection. Moreover, the role of LRP1 in promoting RVFV infection was dependent on physiological levels of cholesterol and on endocytosis. In the human cell line HuH-7, LRP1 also promoted early infection stages of sandfly fever Sicilian virus and La Crosse virus, but had a minor effect on late infection by vesicular stomatitis virus, whereas encephalomyocarditis virus was entirely LRP1-independent. Moreover, siRNA experiments in human Calu-3 cells demonstrated that also SARS-CoV-2 infection benefitted from LRP1. Thus, we identified LRP1 as a host factor that supports infection by a spectrum of RNA viruses.

Endocrine Regulation of Microvascular Receptor-Mediated Transcytosis and Its Therapeutic Opportunities: Insights by PCSK9-Mediated Regulation.

Currently, many neurological disorders lack effective treatment options due to biological barriers that effectively separate the central nervous system (CNS) from the periphery. CNS homeostasis is maintained by a highly selective exchange of molecules, with tightly controlled ligand-specific transport systems at the blood-brain barrier (BBB) playing a key role. Exploiting or modifying these endogenous transport systems could provide a valuable tool for targeting insufficient drug delivery into the CNS or pathological changes in the microvasculature. However, little is known about how BBB transcytosis is continuously regulated to respond to temporal or chronic changes in the environment. The aim of this mini-review is to draw attention to the sensitivity of the BBB to circulating molecules derived from peripheral tissues, which may indicate a fundamental endocrine-operating regulatory system of receptor-mediated transcytosis at the BBB. We present our thoughts in the context of the recent observation that low-density lipoprotein receptor-related protein 1 (LRP1)-mediated clearance of brain amyloid-β (Aβ) across the BBB is negatively regulated by peripheral proprotein convertase subtilisin/kexin type 9 (PCSK9). We hope that our conclusions will inspire future investigations of the BBB as dynamic communication interface between the CNS and periphery, whose peripheral regulatory mechanisms could be easily exploited for therapeutic purposes.

Single-Cell Spatial Analysis Identifies Regulators of Brain Tumor-Initiating Cells.

Characterization of the spatial heterogeneity of glioblastoma identifies regulators of brain tumor-initiating cells and tumor growth that could serve as candidates for therapeutic interventions to improve the prognosis of patients.

Polymorphism of LRP4 Gene (rs9667108) among Post Menopause Women with Osteoporosis.

Many studies have been done to identify the factors that influence the development and progression of osteoporosis. One genetic factor is polymorphisms of LRP4 gene. Regarding the lack of comprehensive study on polymorphisms of LRP4 gene in the north of Iran, mainly Mazandaran Province, we decided to investigate the polymorphism of this gene in postmenopausal women with osteoporosis. This case-control study has been conducted at GhaemShahr Valiasr Hospital on 100 female patients with osteoporosis (average age of 58.1) and 90 healthy females without osteoporosis (average age of 55.2). After sampling and extraction of genomic DNA via of the salt deposition method, the genotype and SNP (rs9667108) polymorphism of LRP4 gene were evaluated with the PCR-RFLP method. Restriction enzymes cut the PCR products. In order to identify patients, their bone mineral density was tested by the DEXA method. The results of digestion (digestion enzyme) were analyzed by MedCalc, SPSS software, Hardy-Weinberg equilibrium, and Chi2. The statistical analysis has shown the significant relationship between SNP (rs9667108) polymorphism and the risk of osteoporosis disease in patients and control groups (P<0.05). In SNP (rs9667108), the GC genotype, compared to GG, increased the risk of disease significantly (1.556 time). Similarly, CC genotype, compared to GG genotype, increased the risk of this disease by 2.091 time. The existence of mutation in the LRP4 gene could increase susceptibility to osteoporosis disease. Moreover, determining this patient's genotype in SNP (rs9667108) can be used to identify individuals who are in endanger osteoporosis.

LRP1 in vascular mural cells modulates cerebrovascular integrity and function in the presence of APOE4.

Cerebrovasculature is critical in maintaining brain homeostasis; its dysregulation often leads to vascular cognitive impairment and dementia (VCID) during aging. VCID is the second most prevalent cause of dementia in the elderly, after Alzheimer's disease (AD), with frequent cooccurrence of VCID and AD. While multiple factors are involved in the pathogenesis of AD and VCID, APOE4 increases the risk for both diseases. A major apolipoprotein E (apoE) receptor, the low-density lipoprotein receptor-related protein 1 (LRP1), is abundantly expressed in vascular mural cells (pericytes and smooth muscle cells). Here, we investigated how deficiency of vascular mural cell LRP1 affects the cerebrovascular system and cognitive performance using vascular mural cell-specific Lrp1-KO mice (smLrp1-/-) in a human APOE3 or APOE4 background. We found that spatial memory was impaired in the 13- to 16-month-old APOE4 smLrp1-/- mice but not in the APOE3 smLrp1-/- mice, compared with their respective littermate control mice. These disruptions in the APOE4 smLrp1-/- mice were accompanied with excess paravascular glial activation and reduced cerebrovascular collagen IV. In addition, blood-brain barrier (BBB) integrity was disrupted in the APOE4 smLrp1-/- mice. Together, our results suggest that vascular mural cell LRP1 modulates cerebrovasculature integrity and function in an APOE genotype-dependent manner.

Obesity-related proximal tubulopathy: an emerging threat to kidney health

Our previous studies have demonstrated that lipid overload leads to lysosomal dysfunction and autophagic stagnation in kidney proximal tubular epithelial cells (PTECs), which contributes to the renal lipotoxicity and eventually leading to the development of an obesity-related kidney disease. Here we identified that TFEB (transcription factor EB) is a modulator of PTECs lipotoxicity. Exposure to saturated fatty acid enhanced TFEB dephosphorylation and nuclear translocation in PTECs. In a mouse model fed with a high-fat diet (HFD), activated TFEB counteracted phospholipid accumulation in lysosomes by promoting lysosomal exocytosis in PTECs. Conversely, HFD-fed, PTECs-specific tfeb−/− deficient mice exhibited increased phospholipid accumulation and autophagic stagnation, which made kidney vulnerable to injury following ischemia-reperfusion. Moreover, a higher body mass index was correlated to reductions in TFEB nuclear translocation in PTECs of chronic kidney disease patients. These data suggest that PTECs are involved in the pathogenesis of obesity-related kidney disease, which is called obesity-related proximal tubulopathy.Abbreviations: EIF4EBP1: eukaryotic translation initiation factor 4E binding protein 1; GAP: GTPase activating protein; HFD: high-fat diet; I/R: ischemia-reperfusion; LMP: lysosomal membrane permeabilization; LRP2: low density lipoprotein receptor-related protein 2; MLBs: multilamellar bodies; MTORC1: mechanistic target of rapamycin kinase complex 1; ORT: obesity-related proximal tubulopathy; PA: palmitic acid; PTEC: proximal tubular epithelial cell; RRAG: Ras related GTP binding; RPS6KB1, ribosomal protein S6 kinase B1; TFEB: transcription factor EB.

Association of Low Levels of Soluble Low-Density Lipoprotein Receptor-Related Protein-1 and COVID-19 Outcomes During the First Wave of Pandemic.

Low-density lipoprotein receptor-related protein-1 (LRP1) is an endocytosis receptor that clears inflammatory proteins from circulation. LRP1 has anti-inflammatory effects that bindpro-inflammatory cytokines or ligands. LRP1 has a soluble form (sLRP1) which can be measured in serum. We report sLRP1 levels in hospitalized patients with COVID-19. The first objectiveof this study is to compare the sLRP1 levels between COVID-19 patientsand healthy controls. The second objective is to examine the association between sLRP1and the clinical outcome of COVID-19. All patients (20-80 years of age) were evaluated in a hospital using a positive PCR test for SARS‑CoV‑2 between April 1, 2020, and June 1, 2020. Controls (n=59) were selected from healthy subjects. sLRP1 levels were measured in patients from the emergency department (ED), inpatient service (IS), and the intensive care unit (ICU). The study included 180 cases. COVID-19 patients showed significantly lower sLRP1 levels compared to controls (1.43 (1.86) versus 2.27 (1.68) μg/mL, respectively, p<0.001). sLRP1 levels were 1.26 (1.81), 1.37 (1.65), and 1.74 (1.98) μg/mL in patients from ED, IS, and ICU, respectively (p=0.022). Patients who were admitted from ED displayed lower sLRP1 levels compared to those who were discharged (median sLRP1 levels were 0.86 versus 1.7 μg/mL, p=0.045). COVID-19 patients display significantly lower sLRP1 levels compared to the healthy controls. sLRP1 levels do not show any association with the clinical outcome of COVID-19. This study demonstrates that LRP1 displays a bidirectional course in COVID-19. A low sLRP1 level is a potential risk factor for susceptibility and hospital admission due to COVID-19. Further studies with larger sample sizes and longer follow-ups are needed to understand the long-term effects of novel biomarkers such as sLRP1 on the outcome of COVID-19.

Balancing WNT signalling in early forebrain development: The role of LRP4 as a modulator of LRP6 function.

The specification of the forebrain relies on the precise regulation of WNT/ß-catenin signalling to support neuronal progenitor cell expansion, patterning, and morphogenesis. Imbalances in WNT signalling activity in the early neuroepithelium lead to congenital disorders, such as neural tube defects (NTDs). LDL receptor-related protein (LRP) family members, including the well-studied receptors LRP5 and LRP6, play critical roles in modulating WNT signalling capacity through tightly regulated interactions with their co-receptor Frizzled, WNT ligands, inhibitors and intracellular WNT pathway components. However, little is known about the function of LRP4 as a potential modulator of WNT signalling in the central nervous system. In this study, we investigated the role of LRP4 in the regulation of WNT signalling during early mouse forebrain development. Our results demonstrate that LRP4 can modulate LRP5- and LRP6-mediated WNT signalling in the developing forebrain prior to the onset of neurogenesis at embryonic stage 9.5 and is therefore essential for accurate neural tube morphogenesis. Specifically, LRP4 functions as a genetic modifier for impaired mitotic activity and forebrain hypoplasia, but not for NTDs in LRP6-deficient mutants. In vivo and in vitro data provide evidence that LRP4 is a key player in fine-tuning WNT signalling capacity and mitotic activity of mouse neuronal progenitors and of human retinal pigment epithelial (hTERT RPE-1) cells. Our data demonstrate the crucial roles of LRP4 and LRP6 in regulating WNT signalling and forebrain development and highlight the need to consider the interaction between different signalling pathways to understand the underlying mechanisms of disease. The findings have significant implications for our mechanistic understanding of how LRPs participate in controlling WNT signalling.

Abstract 2435: Single cell spatial analysis identifies regulators of brain tumor initiating cells

Abstract Glioblastomas (GBMs) are aggressive brain tumors with extensive intratumoral heterogeneity. Here, we used spatial transcriptomics and single-cell ATAC-seq to dissect the transcriptome of distinct anatomical regions of the tumor microenvironment. We identified numerous extracellular matrix (ECM) molecules including biglycan elevated in areas infiltrated with brain tumor-initiating cells (BTICs). Single-cell RNA sequencing showed that the ECM molecules were differentially expressed by cells including injury response versus developmental BTICs. Exogeneous biglycan or overexpression of biglycan resulted in a higher proliferation rate of BTICs, and this was associated mechanistically with LDL receptor-related protein 6 (LRP6) binding and activation of the Wnt/β-catenin pathway. Biglycan-overexpressing BTICs grew to a larger tumor mass and higher mesenchymal phenotypes when implanted intracranially in mice. This study points to the spatial heterogeneity of ECM molecules in the GBM microenvironment and suggests biglycan-LRP6 axis as a therapeutic target to curb GBM growth. Citation Format: Reza Mirzaei, Charlotte D’Mello, Marina Liu, Ana Nikolic, Mehul Kumar, Frank Visser, Pinaki Bose, Marco Gallo, Wee Yong. Single cell spatial analysis identifies regulators of brain tumor initiating cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2435.

Abstract 5051: Assessment of boron delivery peptides with angiopep-2 for boron neutron capture therapy

Abstract Boron neutron capture therapy (BNCT) induces intracellular nuclear reactions that release heavy charged particles to destroy cancer cells during thermal neutron radiation. In order to selectively eliminate cancer cells but avoid harmful effects to normal tissues, targeted delivery of boron-10 in cancer cells is required, whereas the conventional boron delivery agent phenylalanine (BPA) is unsatisfactory. Angiopep-2 is a cell-penetrating peptide that can trigger transcytosis and traverse the blood-brain barrier by recognizing low density lipoprotein-related protein 1. In this study, we developed angiopep-2 for boron delivery in BNCT. Angiopep-2 was labeled with boron-10 using solid-phase peptide synthesis with 4-carboxyphenylboronic acid and fluorenylmethyloxycarbonyl (Fmoc)-protected amino acids, namely ANG-B. Molecular mass of the synthesized ANG-B were validated by mass spectrometry. In a cell proliferation assay, little toxicity of ANG-B was detected. Boron concentrations in 6 cell lines from different cancer types and an intracranial glioblastoma mouse model after treatment with ANG-B or BPA were analyzed by ICP-AES. The in vivo distribution of ANG-B showed that the ratio of boron content of tumor tissue to that of blood (T/B ratio) was 9.42±2.47 at 4h post treatment, while the ratio of boron content of tumor tissue to that of normal brain tissue (T/N ratio) was 5.61±1.0, demonstrated an optimal tumor targeting ability of ANG-B. We further measured the effects of ANG-B in BNCT by clonogenic cell survival assay in vitro or by PET/CT imaging on a glioblastoma mouse model in vivo. Radiation for BNCT was given with neutron flux at 3.0±0.4 × 1011 n/cm2. BNCT with 5 mM ANG-B resulted in 86.5%±5.3% clonogenic cell death, while the number was 72.9%±5.1% for BPA. The effect of ANG-B based BNCT in vivo was also better than BPA. The glioblastoma tumors in ANG-B treated group at 31 days after BNCT were shrank by 62.9% in average, while the BPA treated tumors shrank by only 23.0% (P&amp;lt;0.05). Therefore, we concluded that ANG-B is an efficient boron delivery agent, which may improve BNCT performance in clinical trials. Citation Format: Qi Liu, Jing Xiang, Lin Ma, Qiushi Ren. Assessment of boron delivery peptides with angiopep-2 for boron neutron capture therapy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5051.

Effect of β-amyloid on blood-brain barrier properties and function.

The deposition of beta-amyloid (Aβ) aggregates in the brain, accompanied by impaired cognitive function, is a characteristic feature of Alzheimer's disease (AD). An important role in this process is played by vascular disorders, in particular, a disturbance of the blood-brain barrier (BBB). The BBB controls the entry of Aβ from plasma to the brain via the receptor for advanced glycation end products (RAGE) and the removal of brain-derived Aβ via the low-density lipoprotein receptor-related protein (LRP1). The balance between the input of Aβ to the brain from the periphery and its output is disturbed during AD. Aβ changes the redox-status of BBB cells, which in turn changes the functioning of mitochondria and disrupts the barrier function of endothelial cells by affecting tight junction proteins. Aβ oligomers have the greatest toxic effect on BBB cells, and oligomers are most rapidly transferred by transcytosis from the brain side of the BBB to the blood side. Both the cytotoxic effect of Aβ and the impairment of barrier function are partly due to the interaction of Aβ monomers and oligomers with membrane-bound RAGE. AD therapies based on the disruption of this interaction or the creation of decoys for Aβ are being developed. The question of the transfer of various Aβ isoforms through the BBB is important, since it can influence the development of AD. It is shown that the rate of input of Aβ40 and Aβ42 from the blood into the brain is different. The actual question of the transfer of pathogenic Aβ isoforms with post-translational modifications or mutations through the BBB still remains open.

Whole-Exome Sequencing Revealed the Mutational Profiles of Primary Central Nervous System Lymphoma.

Primary central nervous system lymphoma (PCNSL) is a highly aggressive type of extranodal non-Hodgkin lymphoma, of which approximately 90% of the cases are diffuse large B-cell lymphoma (DLBCL). In recent years, the incidence of PCNSL has significantly increased in women and older men. Although advanced treatments such as high-dose methotrexate (HD-MTX) and targeted agents have been introduced, the prognosis of these patients remains poorer than those with other forms of non-Hodgkin's lymphoma. Twelve cases of Chinese PCNSL were analyzed to detect their genetic alterations using whole-exome sequencing (WES). We identified 448 potential somatic single nucleotide variants (SNVs) with a median of 12 SNVs per PCNSL sample and 35 small indels with potentially protein-changing features in 9 PCNSL samples. We found that myeloid differentiation factor 88 (MYD88) had the highest mutation frequency, which affected the activity of the nuclear factor-κB (NF-κB) pathway. PCNSL samples with low-density lipoprotein receptor-related protein 1B (LRP1B) mutations had a higher mutation rate than samples with wild-type LRP1B. Polycystic kidney and hepatic disease 1 (PKHD1), the causal gene of autosomal recessive polycystic kidney disease (ARPKD), was identified in 2 PCNSL cases and exhibited missense mutations. Pathway analysis revealed enrichment in pathways associated with central carbon metabolism in cancer, renal cell carcinoma, nicotine addiction, bladder cancer, and long-term depression. WES revealed significantly mutated genes associated with the molecular mechanisms of PCNSL, which could serve as therapeutic targets to improve patient outcomes.

Novel mutation in LRP5 gene cause rare osteosclerosis: cases studies and literature review

To study the effects of low-density lipoprotein receptor-related protein 5 (LRP5) gene mutations on bone, and to open up our view of LRP5 and Wnt pathways on bone mass regulation. Three patients with increased bone mineral density or thickened bone cortex were included, who were 30-year-old, 22-year-old and 50-year-old men, respectively. The latter two patients were son and father of a same family. The characteristics of bone X-rays were evaluated in detail. Bone turnover markers were detected, such as procollagen type 1 amino-terminal peptide (P1NP), alkaline phosphatase (ALP), and type 1 collagen carboxyl terminal peptide (β-CTX). Dual energy X-ray absorptiometry (DXA) was used to measure the bone mineral density (BMD) at lumbar spine and proximal femur of the patients. The targeted next-generation sequencing (NGS) technology was used to detect pathogenic gene mutations, which were further verified by Sanger sequencing. Moreover, the gene mutation spectrum and phenotypic characteristics of reported patients with LRP5 gain-of-function mutations were summarized by reviewing the literature. The main characteristics of the first patient were headache, facial paralysis, high BMD (lumbar vertebrae 1–4: 1.877 g/cm2, Z-score: 5.8; total hip: 1.705 g/cm2, Z-score: 5.7), slightly increased P1NP (87.0 ng/mL) and β-CTX (0.761 ng/mL) level, and with thickened bone cortex, especially the cranial vault. The latter two patients showed enlargement of the mandible and enlarged osseous prominence of the tours palatinus. X-rays showed that the bone cortex of skull and long bones were thickened. The bone turnover markers and BMD were normal. All three cases carried novel missense mutations in LRP5 gene, which were mutation in exon 3 (c.586 T > G, p.Trp196Gly) of the first patient, and mutation in exon 20 (c.4240C > A, p.Arg1414Ser) of the latter two patients. Combined with the reported literature, a total of 19 gain-of-function mutations in LRP5 were detected in 113 patients from 33 families. Hotspot mutations included c.724G > A, c.512G > T and c.758C > T. Furthermore, mutations in the exon 3 of LRP5 may cause severe phenotypes. LRP5 gain-of-function mutations can lead to rare autosomal dominant osteosclerosis type Ι (ADO Ι), which was characterized by increased bone mass and thickened bone cortex. In-depth research on the Wnt pathway will be benefit for discovering important mechanisms of bone mass regulation.

FUT2 inhibits the EMT and metastasis of colorectal cancer by increasing LRP1 fucosylation

BackgroundFucosyltransferase 2(FUT2) and its induced α-1,2 fucosylation is associated with cancer metastasis. However, the role of FUT2 in colorectal cancer (CRC) metastasis remains unclear.MethodsThe expression levels and clinical analyses of FUT2 were assessed in CRC samples. Migration and invasion assays, EMT detection, nude mice peritoneal dissemination models and intestinal specific FUT2 knockout mice (FUT2△IEC mice) were used to investigate the effect of FUT2 on metastasis in colorectal cancer. Quantitative proteomics study of glycosylated protein, UEA enrichment, Co-immunoprecipitation identified the mediator of the invasive-inhibiting effects of FUT2.ResultsFUT2 is downregulated in CRC tissues and is positively correlated with the survival of CRC patients. FUT2 is an inhibitor of colorectal cancer metastasis which, when overexpressed, suppresses invasion and tumor dissemination in vitro and in vivo. FUT2 knock-out mice (FUT2△IEC mice) develop AMO and DSS-induced tumors and promote EMT in colorectal cancers. FUT2-induced α-1,2 fucosylation impacts the ability of low-density lipoprotein receptor-related protein 1(LRP1) to suppress colorectal cancer invasion.ConclusionsOur study demonstrated that FUT2 induces α-1,2 fucosylation and inhibits EMT and metastasis of colorectal cancer through LRP1 fucosylation, suggesting that FUT2 may serve as a therapeutic target for colorectal cancer.8zeohEanYa54_QDWABytw7Video

Periplocin targets low density lipoprotein receptor-related protein 4 to attenuate osteoclastogenesis and protect against osteoporosis

Osteoporosis is a common inflammaging-related condition, where long-term accumulation of pro-inflammatory cytokines causes massive bone loss. Periplocin, a cardiotonic steroid isolated from Periploca forrestii, has been proved to reduce inflammation in several inflammatory diseases, such as rheumatoid arthritis. However, its effect and mechanism of inflammation in osteoporosis, in which pro-inflammatory factors accelerate bone loss, has not been well demonstrated. In this study, periplocin attenuated receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation of bone marrow-derived macrophages (BMMs) and RAW264.7 cells in vitro. It reduced osteoclast numbers and bone resorption in a concentration- and time-dependent manner. Further, periplocin treatment resulted in reduced bone loss on mice with ovariectomy-induced osteoporosis in vivo. By transcriptome sequencing, periplocin was indicated to function through inhibition of the mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathways and attenuating interactions between NF-κB and nuclear factor of activated T-cells 1 (NFATc1). It was further detected to bind low density lipoprotein receptor-related protein 4 (LRP4) in osteoclasts to exert anti-inflammatory and anti-osteoclastic effects. Overall, the findings have highlighted a better understanding for the anti-inflammatory and anti-osteoclastic role of periplocin in osteoporosis and its mechanism, bringing new possibilities for osteoporosis treatment.

Human Placental LRP5 and Sclerostin are Increased in Gestational Diabetes Mellitus Pregnancies.

The low-density lipoprotein receptor-related protein 5 (LRP5) and its inhibitor sclerostin, are key components of bone metabolism and potential contributors to type 2 diabetes mellitus susceptibility. This study aims at evaluating the expression of placental LRP5 and sclerostin in pregnancies with gestational diabetes mellitus (GDM) and investigate possible associations with umbilical sclerostin concentrations and clinical outcomes in mothers and their neonates. Twenty-six GDM-mothers and 34 non-GDM mothers of Caucasian origin and their neonates admitted in a gynecology and obstetrics department of a university hospital were included in this study. Demographic data and maternal fasting glucose concentrations (24-28 weeks of gestation) were retrieved from the patients' medical records. Placental LRP5 was determined by immunohistochemistry (IHC) and Western blotting analysis; placental sclerostin was determined by IHC. Umbilical serum sclerostin concentrations were measured by ELISA. Placental sclerostin IHC intensity values were positively correlated with LRP5 values as detected either by IHC (r = 0.529; P < .001) or Western blotting (r = 0.398; P = .008), with pregestational maternal body mass index values (r = 0.299; P = .043) and with maternal fasting glucose concentrations (r = 0.475; P = .009). Placental sclerostin and LRP5 were significantly greater in GDM compared with non-GDM placentas (histo-score: 65.08 ± 17.09 vs 11.45 ± 2.33, P < .001; 145.53 ± 43.74 vs 202.88 ± 58.65, P < .001; respectively). Sclerostin and LRP5 were detected in human placentas. The overexpression of placental sclerostin and LRP5 values in GDM compared with non-GDM pregnancies, as well as the positive association of placental sclerostin values with pregestational maternal body mass index and maternal fasting glucose concentrations may indicate the development of an adaptive mechanism in face of maternal hyperglycemia.

An antibody that targets cell-surface glucose-regulated protein-78 inhibits expression of inflammatory cytokines and plasminogen activator inhibitors by macrophages.

Glucose-regulated protein-78 (Grp78) is an endoplasmic reticulum chaperone, which is secreted by cells and associates with cell surfaces, where it functions as a receptor for activated α2 -macroglobulin (α2 M) and tissue-type plasminogen activator (tPA). In macrophages, α2 M and tPA also bind to the transmembrane receptor, LDL receptor-related protein-1 (LRP1), activating a cell-signaling receptor assembly that includes the NMDA receptor (NMDA-R) to suppress innate immunity. Herein, we demonstrate that an antibody targeting Grp78 (N88) inhibits NFκB activation and expression of proinflammatory cytokines in bone marrow-derived macrophages (BMDMs) treated with the toll-like receptor-4 (TLR4) ligand, lipopolysaccharide, or with agonists that activate TLR2, TLR7, or TLR9. Pharmacologic inhibition of the NMDA-R or deletion of the gene encoding LRP1 (Lrp1) in BMDMs neutralizes the activity of N88. The fibrinolysis protease inhibitor, plasminogen activator inhibitor-1 (PAI1), has been implicated in diverse diseases including metabolic syndrome, cardiovascular disease, and type 2 diabetes. Deletion of Lrp1 independently increased expression of PAI1 and PAI2 in BMDMs, as did treatment of wild-type BMDMs with TLR agonists. tPA, α2 M, and N88 inhibited expression of PAI1 and PAI2 in BMDMs treated with TLR-activating agents. Inhibiting Src family kinases blocked the ability of both N88 and tPA to function as anti-inflammatory agents, suggesting that the cell-signaling pathway activated by tPA and N88, downstream of LRP1 and the NMDA-R, may be equivalent. We conclude that targeting cell-surface Grp78 may be effective in suppressing innate immunity by a mechanism that requires LRP1 and the NMDA-R.

Multi-faceted role of LRP1 in the immune system.

Graft versus host disease (GVHD) represents the major complication after allogeneic hematopoietic stem cell transplantation (Allo-SCT). GVHD-prone patients rely on GVHD prophylaxis (e.g. methotrexate) and generalized anti-GVHD medical regimen (glucocorticoids). New anti-GVHD therapy strategies are being constantly explored, however there is an urgent need to improve current treatment, since GVHD-related mortality reaches 22% within 5 years in patients with chronic GVHD. This review is an attempt to describe a very well-known receptor in lipoprotein studies - the low-density lipoprotein receptor related protein 1 (LRP1) - in a new light, as a potential therapeutic target for GVHD prevention and treatment. Our preliminary studies demonstrated that LRP1 deletion in donor murine T cells results in significantly lower GVHD-related mortality in recipient mice with MHC (major histocompatibility complex) -mismatched HSCT. Given the importance of T cells in the development of GVHD, there is a significant gap in scientific literature regarding LRP1's role in T cell biology. Furthermore, there is limited research interest and publications on this classical receptor molecule in other immune cell types. Herein, we endeavor to summarize existing knowledge about LRP1's role in various immune cells to demonstrate the possibility of this receptor to serve as a novel target for anti-GVHD treatment.