Browsing by Subject "Leptin receptor"

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    Leptin Receptor, a Surface Marker for a Subset of Highly Engrafting Long-term Functional Hematopoietic Stem Cells
    (Springer Nature, 2021) Trinh, Thao; Ropa, James; Aljoufi, Arafat; Cooper, Scott; Sinn, Anthony; Srour, Edward F.; Broxmeyer, Hal E.; Microbiology and Immunology, School of Medicine
    The hematopoietic system is sustained by a rare population of hematopoietic stem cells (HSCs), which emerge during early embryonic development and then reside in the hypoxic niche of the adult bone marrow microenvironment. Although leptin receptor (Lepr)-expressing stromal cells are well-studied as critical regulators of murine hematopoiesis, the biological implications of Lepr expression on HSCs remain largely unexplored. We hypothesized that Lepr+HSCs are functionally different from other HSCs. Using in vitro and in vivo experimental approaches, we demonstrated that Lepr further differentiates SLAM HSCs into two distinct populations; Lepr+HSCs engrafted better than Lepr−HSCs and self-renewed more extensively as noted in secondary transplants. Molecularly, Lepr+HSCs were characterized by a proinflammatory transcriptomic profile enriched for Type-I Interferon and Interferon-gamma (IFN-γ) response pathways, which are known to be critical for the emergence of HSCs in the embryo. We conclude that although Lepr+HSCs represent a minor subset of HSCs, they are highly engrafting cells that possess embryonic-like transcriptomic characteristics, and that Lepr can serve as a reliable marker for functional long term HSCs, which may have potential clinical applicability.
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    tTARGIT AAVs mediate the sensitive and flexible manipulation of intersectional neuronal populations in mice
    (eLife Sciences, 2021-03-11) Sabatini, Paul V.; Wang, Jine; Rupp, Alan C.; Affinati, Alison H.; Flak, Jonathan N.; Li, Chien; Olson, David P.; Myers, Martin G.; Pharmacology and Toxicology, School of Medicine
    While Cre-dependent viral systems permit the manipulation of many neuron types, some cell populations cannot be targeted by a single DNA recombinase. Although the combined use of Flp and Cre recombinases can overcome this limitation, insufficient recombinase activity can reduce the efficacy of existing Cre+Flp-dependent viral systems. We developed a sensitive dual recombinase-activated viral approach: tTA-driven Recombinase-Guided Intersectional Targeting (tTARGIT) adeno-associated viruses (AAVs). tTARGIT AAVs utilize a Flp-dependent tetracycline transactivator (tTA) 'Driver' AAV and a tetracycline response element-driven, Cre-dependent 'Payload' AAV to express the transgene of interest. We employed this system in Slc17a6FlpO;LeprCre mice to manipulate LepRb neurons of the ventromedial hypothalamus (VMH; LepRbVMH neurons) while omitting neighboring LepRb populations. We defined the circuitry of LepRbVMH neurons and roles for these cells in the control of food intake and energy expenditure. Thus, the tTARGIT system mediates robust recombinase-sensitive transgene expression, permitting the precise manipulation of previously intractable neural populations.