Low density lipoprotein receptor related protein 1 and 6 gene variants and ischaemic stroke risk

Astrocytic LRP1 enables mitochondria transfer to neurons and mitigates brain ischemic stroke by suppressing ARF1 lactylation

Low-density lipoprotein receptor-related protein-1 (LRP1) is an endocytic/signaling cell-surface receptor that regulates diverse cellular functions, including cell survival, differentiation, and proliferation. LRP1 has been previously implicated in the pathogenesis of neurodegenerative disorders, but there are inconsistencies in its functions. Therefore, whether and how LRP1 maintains brain homeostasis remains to be clarified. Here, we report that astrocytic LRP1 promotes astrocyte-to-neuron mitochondria transfer by reducing lactate production and ADP-ribosylation factor 1 (ARF1) lactylation. In astrocytes, LRP1 suppressed glucose uptake, glycolysis, and lactate production, leading to reduced lactylation of ARF1. Suppression of astrocytic LRP1 reduced mitochondria transfer into damaged neurons and worsened ischemia-reperfusion injury in a mouse model of ischemic stroke. Furthermore, we examined lactate levels in human patients with stroke. Cerebrospinal fluid (CSF) lactate was elevated in stroke patients and inversely correlated with astrocytic mitochondria. These findings reveal a protective role of LRP1 in brain ischemic stroke by enabling mitochondria-mediated astrocyte-neuron crosstalk.

Activation of LRP6 with HLY78 Attenuates Oxidative Stress and Neuronal Apoptosis via GSK3β/Sirt1/PGC-1α Pathway after ICH

Background

Oxidative stress and neuronal apoptosis have important roles in the pathogenesis after intracerebral hemorrhage (ICH). Previous studies have reported that low-density lipoprotein receptor-related protein 6 (LRP6) exerts neuroprotection in several neurological diseases. Herein, we investigate the role of LRP6 receptor activation with HLY78 to attenuate oxidative stress and neuronal apoptosis after ICH, as well as the underlying mechanism.

Methods

A total of 199 CD1 mice were used. ICH was induced via injection of autologous blood into the right basal ganglia. HLY78 was administered via intranasal injection at 1 h after ICH. To explore the underlying mechanism, LRP6 siRNA and selisistat, a Sirt1 selective antagonist, were injected intracerebroventricularly at 48 h before ICH induction. Neurobehavioral tests, Western blot, and immunofluorescence staining were performed.

Results

The expression of endogenous p-LRP6 was gradually increased and expressed on neurons after ICH. HLY78 significantly improved the short- and long-term neurobehavioral deficits after ICH, which was accompanied with decreased oxidative stress and neuronal apoptosis, as well as increased expression of p-GSK3β, Sirt1, and PGC-1α, as well as downregulation of Romo-1 and C-Caspase-3. LRP6 knockdown or Sirt1 inhibition abolished these effects of HLY78 after ICH.

Conclusion

Our results suggest that administration of HLY78 attenuated oxidative stress, neuronal apoptosis, and neurobehavioral impairments through the LRP6/GSK3β/Sirt1/PGC-1α signaling pathway after ICH.

miR-29c-5p knockdown reduces inflammation and blood–brain barrier disruption by upregulating LRP6

Blood–brain barrier participates in the pathological process of ischemic stroke. MicroRNA-29c-5p was highly expressed in clinical samples from patients with ischemic stroke. In this study, oxygen-glucose deprivation (OGD) treatment of astrocytes enhanced the permeability of brain microvascular endothelial cells (BMECs), and the miR-29c-5p expression was elevated in clinical samples from patients with ischemic stroke. For the function of miR-29c-5p in ischemic stroke, the miR-29c-5p knockdown decreased the permeability and the tight junction protein (TJP) destruction of BMECs and ameliorated the inflammation induced by OGD-treated astrocytes. Mechanistically, miR-29c-5p interacted with lipoprotein receptor-related protein 6 (LRP6) and negatively regulated the LRP6 expression in astrocytes. Moreover, the rescue assays indicated that the interference with miR-29c-5p ameliorated the TJP destruction of BMECs and inflammation caused by OGD-treated astrocytes by increasing the LRP6 expression. Together, miR-29c-5p knockdown decreased the high permeability and the TJP destruction of BMECs and ameliorated the inflammation induced by OGD-treated astrocytes by elevating LRP6 expression.

Chemical composition and protective effect of cerebrospinal fluid of Dan-Deng-Tong-Nao capsules on brain microvascular endothelial cells injured by OGD/R

ETHNOPHARMACOLOGICAL RELEVANCE

Dan-Deng-Tong-Nao Capsules (DDTNC) is a Chinese patent medicine and has been used in treating cerebral ischemic stroke (IS) for a long time in China, protection of brain microvascular endothelial cells (BMECs) is the main treatment strategy. But the holistic chemical information and potential bioactive components of DDTNC on protecting BMECs and its underlying mechanism is still unclear.

AIM OF THE STUDY

To identify the active ingredients of DDTNC and to explore the protective effects of DDTNC on BMECs associated with Wnt/β-catenin pathway.

MATERIALS AND METHODS

The components of DDTNC and cerebrospinal fluid containing composition of DDTNC (DDTNC-CSF) were detected by High performance liquid chromatography combined with Diode array detector (HPLC-DAD) and Ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS), respectively. The experiment rat model was established with middle cerebral artery occlusion (MCAO), the therapeutic effects of DDTNC were assessed by Longa assay and TTC staining. The cerebral micro vessel density was determined by immunofluorescence staining. The injured BMECs caused by oxygen-glucose deprivation and reperfusion (OGD/R) was used to evaluate the protective effect of cerebrospinal fluid containing composition of DDTNC (DDTNC-CSF). The cell survival rate was detected by the method of CCK-8, the intracellular Ca²⁺ and reactive oxygen species (ROS) was estimated by Fluo-3. Moreover, the proteins of Bax, Bcl-2, Wnt, β-catenin, GSK-3β was determined by Western blotting.

RESULTS

The RSD values of all methodological studies were less than 3.0%. A total of 20 compounds were detected under the optimized HPLC-DAD chromatographic condition. In the UPLC-Q-TOF-MS negative mode, peak 1 and peak 2 were detecteted in DDTNC-CSF and was identified as Danshensu and Puerarin, respectively. In the UPLC-Q-TOF-MS positive mode, peak 1 and peak 3 were detecteted in DDTNC-CSF and was identified as Danshensu and Scutellarin, respectively. DDTNC significantly decreased the Longa values and infarct volume and significantly increased the cerebral microvessel density of the MCAO rats. The accumulation of intracellular Ca²⁺ and ROS in BMECs injured by OGD/R decreased significantly in DDTNC-CSF group. The expression of Bcl-2, β-catenin, wnt-1 was upregulated by DDTNC-CSF and the level of Bax and GSK3β could be downregulated by DDTNC-CSF.

CONCLUSION

The present study provided a scientific basis for revealing the mechanism of DDTNC in the treatment of IS and DDTNC is expected to be an effective drug for the treatment of IS.

Genetic and Genomic Epidemiology of Stroke in People of African Ancestry

Stroke is one of the leading causes of disability and death worldwide and places a significant burden on healthcare systems. There are significant racial/ethnic differences in the incidence, subtype, and prognosis of stroke, between people of European and African ancestry, of which only about 50% can be explained by traditional stroke risk facts. However, only a small number of genetic studies include individuals of African descent, leaving many gaps in our understanding of stroke genetics among this population. This review article highlights the need for and significance of including African-ancestry individuals in stroke genetic studies and points to the efforts that have been made towards this direction. Additionally, we discuss the caveats, opportunities, and next steps in African stroke genetics-a field still in its infancy but with great potential for expanding our understanding of stroke biology and for developing new therapeutic strategies.

MiR-30a suppresses clear cell renal cell carcinoma proliferation and metastasis by targeting LRP6

Recently, the role of miR-30a in tumor development has attracted extensive attention. In this study, we aimed to elucidate the role of miR-30a and its associated target low-density lipoprotein receptor-related protein 6 (LRP6) in clear cell renal cell carcinoma (ccRCC) cells. Here, miR-30a was markedly down-regulated in ccRCC tissues and cells, and was correlated with the advanced TNM stage and poor prognosis. By contrast, LRP6 protein level was increased in ccRCC specimens and cell lines, and inversely correlated with miR-30a expression. Stable overexpression of miR-30a suppressed cell proliferation in vitro, impeded tumor growth in vivo, prevented migration and invasion, and triggered apoptosis of ccRCC cells. Also, over-expression of miR-30a in ccRCC cells promoted the expression of the epithelial marker E-cadherin and reduced the levels of mesenchymal markers. Mechanistically, the dual-luciferase reporter, RNA immunoprecipitation and western blot assays confirmed that miR-30a directly targeted the 3'-untranslated regions of LRP6 to inhibit its expression. Further, miR-30a-mediated effect was partially reversed by co-transfection with LRP6 plasmids or enhanced by silencing of LRP6. In conclusion, miR-30a exhibits effective antitumor properties by targeting LRP6 in proliferation and metastasis of ccRCC. This study could provide new insights into the treatment of ccRCC.

Serum anti-LRPAP1 is a common biomarker for digestive organ cancers and atherosclerotic diseases

Some cancers are related to atherosclerotic diseases; therefore, these two types of disease may share some antibody biomarkers in common. To investigate this, a first screening of sera was performed from patients with esophageal squamous cell carcinoma (ESCC) or acute ischemic stroke (AIS) for serological identification of antigens using recombinant cDNA expression cloning (SEREX). The amplified luminescent proximity homogeneous assay‐linked immunosorbent assay (AlphaLISA) method, which incorporates glutathione donor beads and anti‐human IgG acceptor beads, was used to evaluate serum antibody levels. SEREX screening identified low‐density lipoprotein receptor–related protein–associated protein 1 (LRPAP1) as a target antigen of serum IgG antibodies in the sera of patients with ESCC or AIS. Antigens, including recombinant glutathione S‐transferase–fused LRPAP1 protein, were prepared to examine serum antibody levels. AlphaLISA revealed significantly higher antibody levels against the LRPAP1 protein in patients with solid cancers such as ESCC and colorectal carcinoma and some atherosclerosis‐related diseases such as AIS and diabetes mellitus compared with healthy donors. Correlation analysis revealed that the elevated serum antibody levels against LRPAP1 were associated with smoking, a well‐known risk factor for both cancer and atherosclerosis. Serum LRPAP1 antibody is therefore a common marker for the early diagnosis of some cancers and atherosclerotic diseases and may reflect diseases caused by habitual smoking.

Wnt Pathway: An Emerging Player in Vascular and Traumatic Mediated Brain Injuries

The Wnt pathway, which comprises the canonical and non-canonical pathways, is an evolutionarily conserved mechanism that regulates crucial biological aspects throughout the development and adulthood. Emergence and patterning of the nervous and vascular systems are intimately coordinated, a process in which Wnt pathway plays particularly important roles. In the brain, Wnt ligands activate a cell-specific surface receptor complex to induce intracellular signaling cascades regulating neurogenesis, synaptogenesis, neuronal plasticity, synaptic plasticity, angiogenesis, vascular stabilization, and inflammation. The Wnt pathway is tightly regulated in the adult brain to maintain neurovascular functions. Historically, research in neuroscience has emphasized essentially on investigating the pathway in neurodegenerative disorders. Nonetheless, emerging findings have demonstrated that the pathway is deregulated in vascular- and traumatic-mediated brain injuries. These findings are suggesting that the pathway constitutes a promising target for the development of novel therapeutic protective and restorative interventions. Yet, targeting a complex multifunctional signal transduction pathway remains a major challenge. The review aims to summarize the current knowledge regarding the implication of Wnt pathway in the pathobiology of ischemic and hemorrhagic stroke, as well as traumatic brain injury (TBI). Furthermore, the review will present the strategies used so far to manipulate the pathway for therapeutic purposes as to highlight potential future directions.

The involvement of the canonical Wnt-signaling receptor LRP5 and LRP6 gene variants with ADHD and sexual dimorphism: Association study and meta-analysis

Wnt-signaling is one of the most abundant pathways involved in processes such as cell-proliferation, -polarity, and -differentiation. Altered Wnt-signaling has been linked with several neurodevelopmental disorders including attention-deficit/hyperactivity disorder (ADHD) as well as with cognitive functions, learning and memory. Particularly, lipoprotein receptor-related protein 5 (LRP5) or LRP6 coreceptors, responsible in the activation of the canonical Wnt-pathway, were associated with cognitive alterations in psychiatric disorders. Following the hypothesis of Wnt involvement in ADHD, we investigated the association of genetic variations in LRP5 and LRP6 genes with three independent child and adolescent ADHD (cADHD) samples (total 2,917 participants), followed by a meta-analysis including previously published data. As ADHD is more prevalent in males, we stratified the analysis according to sex and compared the results with the recent ADHD Psychiatric Genomic Consortium (PGC) GWAS. Meta-analyzing our data including previously published cADHD studies, association of LRP5 intronic rs4988319 and rs3736228 (Ala1330Val) with cADHD was observed among girls (OR = 1.80 with 95% CI = 1.07-3.02, p = .0259; and OR = 2.08 with 95% CI = 1.01-4.46, p = .0026, respectively), whereas in boys association between LRP6 rs2302685 (Val1062Ile) and cADHD was present (OR = 1.66, CI = 1.20-2.31, p = .0024). In the PGC-ADHD dataset (using pooled data of cADHD and adults) tendency of associations were observed only among females with OR = 1.09 (1.02-1.17) for LRP5 rs3736228 and OR = 1.18 (1.09-1.25) for LRP6 rs2302685. Together, our findings suggest a potential sex-specific link of cADHD with LRP5 and LRP6 gene variants, which could contribute to the differences in brain maturation alterations in ADHD affected boys and girls, and suggest possible therapy targets.

LRP1 (Low-Density Lipoprotein Receptor-Related Protein 1) Regulates Smooth Muscle Contractility by Modulating Ca2+ Signaling and Expression of Cytoskeleton-Related Proteins

Objective- Mutations affecting contractile-related proteins in the ECM (extracellular matrix), microfibrils, or vascular smooth muscle cells can predispose the aorta to aneurysms. We reported previously that the LRP1 (low-density lipoprotein receptor-related protein 1) maintains vessel wall integrity, and smLRP1-/- mice exhibited aortic dilatation. The current study focused on defining the mechanisms by which LRP1 regulates vessel wall function and integrity. Approach and Results- Isometric contraction assays demonstrated that vasoreactivity of LRP1-deficient aortic rings was significantly attenuated when stimulated with vasoconstrictors, including phenylephrine, thromboxane receptor agonist U-46619, increased potassium, and L-type Ca2+ channel ligand FPL-64176. Quantitative proteomics revealed proteins involved in actin polymerization and contraction were significantly downregulated in aortas of smLRP1-/- mice. However, studies with calyculin A indicated that although aortic muscle from smLRP1-/- mice can contract in response to calyculin A, a role for LRP1 in regulating the contractile machinery is not revealed. Furthermore, intracellular calcium imaging experiments identified defects in calcium release in response to a RyR (ryanodine receptor) agonist in smLRP1-/- aortic rings and cultured vascular smooth muscle cells. Conclusions- These results identify a critical role for LRP1 in modulating vascular smooth muscle cell contraction by regulating calcium signaling events that potentially protect against aneurysm development.

Genetic Variants in LRP1 and ULK4 Are Associated with Acute Aortic Dissections

Acute aortic dissections are a preventable cause of sudden death if individuals at risk are identified and surgically repaired in a non-emergency setting. Although mutations in single genes can be used to identify at-risk individuals, the majority of dissection case subjects do not have evidence of a single gene disorder, but rather have the other major risk factor for dissections, hypertension. Initial genome-wide association studies (GWASs) identified SNPs at the FBN1 locus associated with both thoracic aortic aneurysms and dissections. Here, we used the Illumina HumanExome array to genotype 753 individuals of European descent presenting specifically with non-familial, sporadic thoracic aortic dissection (STAD) and compared them to the genotypes of 2,259 control subjects from the Atherosclerosis Risk in Communities (ARIC) study matched for age, gender, and, for the majority of cases, hypertension. SNPs in FBN1, LRP1, and ULK4 were identified to be significantly associated with STAD, and these results were replicated in two independent cohorts. Combining the data from all cohorts confirmed an inverse association between LRP1 rs11172113 and STAD (p = 2.74 × 10(-8); OR = 0.82, 95% CI = 0.76-0.89) and a direct association between ULK4 rs2272007 and STAD (p = 1.15 × 10(-9); OR = 1.35, 95% CI = 1.23-1.49). Genomic copy-number variation analysis independently confirmed that ULK4 deletions were significantly associated with development of thoracic aortic disease. These results indicate that genetic variations in LRP1 and ULK4 contribute to risk for presenting with an acute aortic dissection.