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Innate immunity is associated with Alzheimer's disease.sup.1, but the influence of immune activation on the production of amyloid-[beta] is unknown.sup.2,3. Here we identify interferon-induced transmembrane protein 3 (IFITM3) as a [gamma]-secretase modulatory protein, and establish a mechanism by which inflammation affects the generation of amyloid-[beta]. Inflammatory cytokines induce the expression of IFITM3 in neurons and astrocytes, which binds to [gamma]-secretase and upregulates its activity, thereby increasing the production of amyloid-[beta]. The expression of IFITM3 is increased with ageing and in mouse models that express familial Alzheimer's disease genes. Furthermore, knockout of IFITM3 reduces [gamma]-secretase activity and the formation of amyloid plaques in a transgenic mouse model (5xFAD) of early amyloid deposition. IFITM3 protein is upregulated in tissue samples from a subset of patients with late-onset Alzheimer's disease that exhibit higher [gamma]-secretase activity. The amount of IFITM3 in the [gamma]-secretase complex has a strong and positive correlation with [gamma]-secretase activity in samples from patients with late-onset Alzheimer's disease. These findings reveal a mechanism in which [gamma]-secretase is modulated by neuroinflammation via IFITM3 and the risk of Alzheimer's disease is thereby increased. The IFITM3 innate immunity protein directly binds presenilin near the active site and upregulates [gamma]-secretase activity and the production of amyloid-[beta], and IFITM3 is upregulated in patients with late-onset Alzheimer's disease., Author(s): Ji-Yeun Hur [sup.1] , Georgia R. Frost [sup.1] [sup.2] , Xianzhong Wu [sup.1] , Christina Crump [sup.1] [sup.3] , Si Jia Pan [sup.1] , Eitan Wong [sup.1] , Marilia [...]

Retention of long-term repopulating hematopoietic stem cells (LT-HSCs) in the bone marrow is essential for hematopoiesis and for protection from myelotoxic injury. We report that signaling cascades that are traditionally viewed as coagulation related also control retention of endothelial protein C receptor-positive (EPCR[sup.+]) LT-HSCs in the bone marrow and their recruitment to the blood via two pathways mediated by protease activated receptor 1 (PAR1). Thrombin-PAR1 signaling induces nitric oxide (NO) production, leading to EPCR shedding mediated by tumor necrosis factor-[alpha]-converting enzyme (TACE), enhanced CXCL12-CXCR4-induced motility and rapid stem and progenitor cell mobilization. Conversely, bone marrow blood vessels provide a microenvironment enriched with activated protein C (aPC) that retains EPCR[sup.+] LT-HSCs by limiting NO generation, reducing Cdc42 activity and enhancing integrin VLA4 affinity and adhesion. Inhibition of NO production by aPC-EPCR-PAR1 signaling reduces progenitor cell egress from the bone marrow, increases retention of bone marrow NO[sup.low] EPCR[sup.+] LT-HSCs and protects mice from chemotherapy-induced hematological failure and death. Our study reveals new roles for PAR1 and EPCR in controlling NO production to balance maintenance and recruitment of bone marrow EPCR[sup.+] LT-HSCs, with potential clinical relevance for stem cell transplantation., Author(s): Shiri Gur-Cohen [1]; Tomer Itkin [1]; Sagarika Chakrabarty [2]; Claudine Graf [3]; Orit Kollet [1]; Aya Ludin [1]; Karin Golan [1]; Alexander Kalinkovich [1]; Guy Ledergor [1, 4]; Eitan [...]

Background: Amyloid beta (Aß) extracellular deposits are one of the pathohistological hallmarks of Alzheimer's Disease (AD). In recent years intracellular accumulation of Aß has been linked with early pathogenic mechanisms. Recent reports now associate intracellular Aβ accumulation, and lysosomal disfunction as an early event in the disease, preceding extracellular amyloid‐deposits. Today methods to visualize intracellular Aβ accumulation rely on antibody staining or pre‐labeled Aβ. There is an outstanding need for live‐imaging tools capable of monitoring Aβ dynamics at the cellular level. Method: We have developed an optical sensor that can monitor Aß in live cells transiently. Single wall carbon nanotubes (SWCNT) present advantages as optical sensors owing to their near‐infrared emission, as well as photostability and high‐sensitivity. SWCNT emission spectra (wavelength ranges of 1100‐1150nm) is within the biological transparency window (1000‐1700nm) allowing for optimal imaging in live samples. SWCNT were non‐covalently biofunctionalized; by which we confer selectivity to Aβ. To obtain intracellular detection we used two cell lines: monocytes (THP‐1) and differentiated SH‐SY5Y. Cells were incubated with functionalized nanotubes. We utilized near‐infrared spectroscopy and hyper‐spectral microscopy to obtain spectral response from live‐cells. Result: We developed and characterized a new class of bio‐functionalized intrinsically photoluminescent SWCNT sensor that can detect Aß via shifting of their intrinsic near‐infrared emission wavelength. Our biofunctionalized sensors specifically recognize Aβ in the solution phase, showing a monochromatic center wavelength decrease in a dose‐dependent fashion. The reporters show high specificity compared to competing analytes and in serum samples. In cell models, nanosensors accumulate intracellularly and probe Aβ introduced to the cells specifically. Finally, initial through‐skull near‐IR imaging in‐vivo in an AD model (5XFAD), following intracranial injection, show significant decrease in central wavelength in AD mice compared to wild type. Conclusion: The SWCNT sensor provide a framework for dynamically investigating Aβ in live samples. We believe utilizing the nanosensors can enhance the study of Aβ ‐pathogenic mechanism, structure and molecular function and consequently improve and accelerate effective amyloid‐targeted therapies. [ABSTRACT FROM AUTHOR]

In the version of this article initially published, the first author's name was incorrect. The error has been corrected in the HTML and PDF versions of the article. Nat. Med. [...]

Retention of long-term repopulating hematopoietic stem cells (LT-HSCs) in the bone marrow is essential for hematopoiesis and for protection from myelotoxic injury. We report that signaling cascades that are traditionally viewed as coagulation related also control retention of endothelial protein C receptor-positive (EPCR+) LT-HSCs in the bone marrow and their recruitment to the blood via two pathways mediated by protease activated receptor 1 (PAR1). Thrombin-PAR1 signaling induces nitric oxide (NO) production, leading to EPCR shedding mediated by tumor necrosis factor-α-converting enzyme (TACE), enhanced CXCL12-CXCR4-induced motility and rapid stem and progenitor cell mobilization. Conversely, bone marrow blood vessels provide a microenvironment enriched with activated protein C (aPC) that retains EPCR+ LT-HSCs by limiting NO generation, reducing Cdc42 activity and enhancing integrin VLA4 affinity and adhesion. Inhibition of NO production by aPC-EPCR-PAR1 signaling reduces progenitor cell egress from the bone marrow, increases retention of bone marrow NOlow EPCR+ LT-HSCs and protects mice from chemotherapy-induced hematological failure and death. Our study reveals new roles for PAR1 and EPCR in controlling NO production to balance maintenance and recruitment of bone marrow EPCR+ LT-HSCs, with potential clinical relevance for stem cell transplantation. [ABSTRACT FROM AUTHOR]