Ni Cheng

BACKGROUND: Thrombosis often starts with platelet adhesion via the interaction between VWF (von Willebrand factor) and its platelet receptor, the GPIb-IX (glycoprotein Ib-IX) complex. GPIb-IX also induces intracellular signals, stimulating VWF-, thrombin- and collagen-induced platelet activation. GPIb-IX signaling requires SFK (Src family kinase) Lyn. However, it remains unclear how Lyn mediates GPIb-IX signaling, whether Lyn directly binds to GPIb-IX, and if it is possible to target this signaling node for developing novel antithrombotics. METHODS: Direct binding of recombinant Lyn to glycoprotein Ibβ (GPIbβ) fragments was performed to map the Lyn-binding site. An inhibitory peptide mPLβ was then synthesized and tested for its interference with Lyn-GPIb-IX co-immunoprecipitation, platelet adhesion, ristocetin-, thrombin- or collagen-induced platelet aggregation/secretion, FeCl3-induced mouse carotid artery thrombosis and tail bleeding time. Biomembrane force probe was used to determine VWF-GPIb molecular bonding and consequent signaling. RESULTS: Lyn directly binds to GPIbβ (V144-A161) at the transmembrane/cytoplasmic domain interface, which is critical for not only the extracellular GPIb-IX ligand–induced intracellular signaling but also transmits outbound signals enhancing VWF-GPIb-IX interaction. The peptide mPLβ inhibited VWF-induced or α-thrombin-induced GPIbβ-Lyn interaction, Lyn/SFK activation, stable platelet adhesion and aggregation, and, notably, reduced GPIb-mediated platelet adhesion to VWF even in the presence of integrin inhibitors. BFP study further shows that mPLβ reduces the VWF-A1 domain-GPIb adhesion frequency and inhibits force-induced A1-mediated intraplatelet calcium elevation. Importantly, mPLβ formulated as a high-loading peptide nanoparticle inhibited platelet adhesion/aggregation induced by collagen and in vivo arterial thrombosis with a mild effect in prolonging bleeding time. CONCLUSIONS: Direct binding of Lyn to GPIbβ mediates 2-way GPIb-IX signaling to activate platelets and modulate VWF-GPIb interaction. Lyn-mediated GPIb-IX signaling is critical for platelet adhesion and aggregation induced by VWF and collagen and in arterial thrombosis. Targeting the Lyn-GPIbβ interaction has the potential for treating GPIb-IX-dependent thrombosis.

The integrins and G protein-coupled receptors are both fundamental in cell biology. The cross talk between these two, however, is unclear. Here we show that β₃ integrins negatively regulate G protein-coupled signaling by directly inhibiting the Gα₁₃-p115RhoGEF interaction. Furthermore, whereas β₃ deficiency or integrin antagonists inhibit integrin-dependent platelet aggregation and exocytosis (granule secretion), they enhance G protein-coupled RhoA activation and integrin-independent secretion. In contrast, a β₃-derived Gα₁₃-binding peptide or Gα₁₃ knockout inhibits G protein-coupled RhoA activation and both integrin-independent and dependent platelet secretion without affecting primary platelet aggregation. In a mouse model of myocardial ischemia/reperfusion injury in vivo, the β₃-derived Gα₁₃-binding peptide inhibits platelet secretion of granule constituents, which exacerbates inflammation and ischemia/reperfusion injury. These data establish crucial integrin-G protein crosstalk, providing a rationale for therapeutic approaches that inhibit exocytosis in platelets and possibly other cells without adverse effects associated with loss of cell adhesion.

Prostate cancer (PC) is recognized as a common malignancy in male patients. Long non‑coding RNA (lncRNA) has been implicated in the development of PC. Recently, long intergenic non‑protein coding RNA 1207 (LINC01207) has been reported to regulate the carcinogenesis of multiple cancer types. However, its role in the progression of PC remains to be determined. The aim of the present study was to investigate the expression profile, clinicopathological implication and molecular mechanism of action of LINC01207 in the progression of PC. LINC01207 expression levels were compared between PC tumor and paired normal tissue samples from The Cancer Genome Atlas. The expression of LINC01207 was further analyzed in PC cell lines and a normal prostatic cell line. The role of LINC01207 in proliferation, migration and invasion of PC cells was examined using small interfering RNA‑mediated silencing. Western blot analysis was used to investigate the changes in protein levels underlying the mechanism of action of LINC01207. The role of LINC01207 in tumorigenesis was evaluated in a xenograft model. LINC01207 was upregulated in PC tumor samples from TCGA data compared with paired normal tissue. LINC01207 expression was significantly increased in PC cells and tumor tissues compared with in normal prostate cells (RWPE1) and normal prostate tissues, respectively. Furthermore, LINC01207 silencing inhibited PC cell proliferation and colony formation and induced apoptosis. Mechanistic experiments showed that LINC01207 promoted carcinogenesis by sponging miR‑1182 to regulate the protein levels of AKT3 in PC cell lines. Thus, the findings of the present study indicated that LINC01207 might play a role in the tumorigenesis of PC and may serve as a therapeutic target for PC treatment.

Neutrophil migration requires β2 integrins and chemoattractant receptor signaling for motility and directionality. G protein subunit Gα13 can facilitate cell migration by mediating RhoA activation induced by G protein–coupled receptors. However, the possible role of Gα13-integrin interaction in migration is unclear. In this study, we show that Gα13−/− neutrophils are deficient in transendothelial migration and migration on β2 integrin ligand ICAM-1. However, unlike G protein–coupled receptors and integrin inside-out signaling pathways, Gα13 is important in migration velocity and neutrophil spreading but not in directionality nor cell adhesion. Importantly, neutrophil recruitment in vivo was also inhibited in Gα13−/− mice, suggesting the importance of Gα13 in transendothelial migration of neutrophils in vitro and in vivo. Furthermore, a synthetic peptide (MB2mP6) derived from the Gα13 binding site of β2 inhibited Gα13-β2 interaction and Gα13-mediated transient RhoA inhibition in neutrophils, suggesting that this peptide inhibited integrin outside-in signaling. MB2mP6 inhibited migration of control neutrophils through endothelial cell monolayers or ICAM-1–coated filters, but was without further effect on Gα13−/− neutrophils. It also inhibited integrin-dependent neutrophil migration velocity without affecting directionality. In vivo, MB2mP6 markedly inhibited neutrophil infiltration into the cardiac tissues induced by ischemia/reperfusion injury. Thus, Gα13-dependent outside-in signaling enables integrin-dependent neutrophil motility without affecting directionality and may be a new therapeutic target for inhibiting neutrophil trafficking but not adhesion.

Systemic inflammation as manifested in sepsis is an excessive, life-threatening inflammatory response to severe bacterial or viral infection or extensive injury. It is also a thrombo-inflammatory condition associated with vascular leakage/hemorrhage and thrombosis that is not effectively treated by current anti-inflammatory or anti-thrombotic drugs. Here, we show that MB2mP6 peptide nanoparticles, targeting the Gα₁₃-mediated integrin “outside-in” signaling in leukocytes and platelets, inhibited both inflammation and thrombosis without causing hemorrhage/vascular leakage. MB2mP6 improved mouse survival when infused immediately or hours after onset of severe sepsis. Furthermore, platelet Gα₁₃ knockout inhibited septic thrombosis whereas leukocyte Gα₁₃ knockout diminished septic inflammation, each moderately improving survival. Dual platelet/leukocyte Gα₁₃ knockout inhibited septic thrombosis and inflammation, further improving survival similar to MB2mP6. These results demonstrate that inflammation and thrombosis independently contribute to poor outcomes and exacerbate each other in systemic inflammation, and reveal a concept of dual anti-inflammatory/anti-thrombotic therapy without exacerbating vascular leakage.

Objective: Despite the importance of reactive oxygen species (ROS) and NOX (nicotinamide adenine dinucleotide phosphate [NADPH] oxidase) 2 in platelet activation and in vivo thrombosis, it is unclear how ROS and NOX2 play a role in platelet activation and why NOX2 deficiencies in humans and mice do not affect hemostasis. Outside-in signaling of integrin α _IIb β ₃ mediates platelet response to shear stress, secondary platelet activation, and thrombus expansion and is critical to thrombosis but dispensable for hemostasis. We studied the mechanisms of platelet ROS generation, ROS-mediated platelet response, and the role of ROS in integrin α _IIb β ₃ outside-in signaling. Approach and Results: ROS generation in activated platelets was low and slow without shear but was robust under shear. Shear-enhanced ROS generation and activation of p47phox, an important regulatory subunit of NOX2, were diminished by the integrin antagonist integrilin or β ₃ knockout, and by Gα ₁₃ knockout or blocking the Gα ₁₃ -β ₃ interaction. Resting platelets spreading on integrin ligand fibrinogen also Gα ₁₃ -dependently stimulated ROS generation and p47phox activation. Hence, Gα ₁₃ -mediated outside-in signaling induces NOX2 activation and ROS generation which is greatly enhanced by shear. Outside-in NOX2 activation requires Src, phosphoinositide 3-kinase and Akt downstream of Gα ₁₃ . Importantly, NOX2-knockout platelets showed defective ROS generation, reduced platelet spreading without shear, and reduced platelet adhesion and thrombus volume on collagen and VWF (von Willibrand factor) under shear, whereas ROS inhibition diminished activation of tyrosine kinase Syk. Conclusions: Outside-in signaling activates the mainly NOX2-mediated ROS generation, which mediates Syk-dependent secondary platelet activation, adhesion, and thrombosis with minimal effect on hemostasis.

Multiple myeloma is a refractory malignant disease characterized by clonal hyper proliferation of plasma cells in the bone marrow microenvironment. In recent years, its incidence has gradually increased and it is younger. Magnetic resonance imaging is a medical imaging technology that has developed rapidly in recent years. Its application and promotion have greatly improved the level of medical services and scientific research. It has become one of the most important examination methods for myeloma. Magnetic resonance imaging has a high soft tissue resolution and has a high detection rate for multiple myeloma. However, there are few studies on the MM magnetic resonance scanning protocol, and the initial or follow-up examination methods have not been unified. Therefore, this paper subjectively and objectively evaluates the clinical images of MM patients with multiple sequences of magnetic resonance of different devices, and hopes to provide more advantageous examination methods for clinicians and patients. The experimental results show that magnetic resonance multisequence imaging can be ideal for clinical diagnosis and follow-up of MM patients.

Inefficient delivery is a major obstacle to the development of peptide-based drugs targeting the intracellular compartment. We recently showed that selectively inhibiting integrin outside-in signaling using a peptide (mP6) derived from the Gα₁₃-binding ExE motif within the integrin β₃ cytoplasmic domain had antithrombotic effects. Here, we engineered lipid-stabilized, high-loading peptide nanoparticles (HLPN), in which a redesigned ExE peptide (M3mP6) constituted up to 70% of the total nanoparticle molarity, allowing efficient in vivo delivery. We observed that M3mP6 HLPN inhibited occlusive thrombosis more potently than a clopidogrel/aspirin combination without adverse effects on hemostasis in rodents. Furthermore, M3mP6 HLPN synergized with P2Y12 receptor inhibitors or the clopidogrel/aspirin combination in preventing thrombosis, without exacerbating hemorrhage. M3mP6 HLPN also inhibited intravascular coagulation more potently than the P2Y12 inhibitor cangrelor. Postischemia injection of M3mP6 HLPN protected the heart from myocardial ischemia–reperfusion injury in a mouse model. This study demonstrates an efficient in vivo peptide delivery strategy for a therapeutic that not only efficaciously prevented thrombosis with minimal bleeding risk but also protected from myocardial ischemia–reperfusion injury in mice.

Lipopolysaccharide (LPS) is a major microbial mediator for tissue injury and sepsis resulting from Gram‐negative bacterial infection. LPS is an external factor that induces robust expression of serum amyloid A (SAA), a major constituent of the acute‐phase proteins, but the relationship between SAA expression and LPS‐induced tissue injury remains unclear. Here, we report that mice with inducible transgenic expression of human SAA1 are partially protected against inflammatory response and lung injury caused by LPS and cecal ligation and puncture (CLP). In comparison, transgenic SAA1 does not attenuate TNFα‐induced lung inflammation and injury. The SAA1 expression level correlates inversely with the endotoxin concentrations in serum and lung tissues since SAA1 binds directly to LPS to form a complex that promotes LPS uptake by macrophages. Disruption of the SAA1‐LPS interaction with a SAA1‐derived peptide partially reduces the protective effect and exacerbates inflammation. These findings demonstrate that acute‐phase SAA provides innate feedback protection against LPS‐induced inflammation and tissue injury. Synopsis High‐level production of serum amyloid A is a hallmark of acute‐phase response. Human SAA1 interacts with LPS, which promotes LPS clearance and reduces serum endotoxin levels in SAA1 transgenic mice. Transgenic expression of human SAA1 in mice simulates SAA production in acute‐phase response. SAA1 attenuates lung inflammation, improves survival and reduces serum endotoxin levels in mice receiving CLP or LPS. SAA1 forms a complex with LPS and promotes LPS uptake by macrophages. Disruption of the SAA1‐LPS interaction abrogates the protective effect of SAA1.