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 mice to manipulate LepRb neurons of the ventromedial hypothalamus (VMH; LepRb neurons) while omitting neighboring LepRb populations. We defined the circuitry of LepRb 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.
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http://dx.doi.org/10.7554/eLife.66835 | DOI Listing |
bioRxiv
September 2024
Center for Diabetes and Endocrine Research, Department of Physiology and Pharmacology, University of Toledo College of Medicine, Toledo, Ohio, USA.
Leptin receptor (LepRb)-expressing neurons are known to link body growth and reproduction, but whether these functions are mediated via insulin-like growth factor 1 receptor (IGF1R) signaling is unknown. IGF-1 and insulin can bind to each other's receptors, permitting IGF-1 signaling in the absence of IGF1R. Therefore, we created mice lacking IGF1R exclusively in LepRb neurons (IGF1R mice) and simultaneously lacking IGF1R and insulin receptor (IR) in LepRb neurons (IGF1R/IR mice) and then characterized their body growth, bone morphology, reproductive and metabolic functions.
View Article and Find Full Text PDFNat Commun
September 2024
Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48105, USA.
Endoplasmic reticulum (ER) homeostasis in the hypothalamus has been implicated in the pathogenesis of diet-induced obesity (DIO) and type 2 diabetes; however, the underlying molecular mechanism remain vague and debatable. Here we report that SEL1L-HRD1 protein complex of the highly conserved ER-associated protein degradation (ERAD) machinery in POMC-expressing neurons ameliorates diet-induced obesity and its associated complications, partly by regulating the turnover of the long isoform of Leptin receptors (LepRb). Loss of SEL1L in POMC-expressing neurons attenuates leptin signaling and predisposes mice to HFD-associated pathologies including fatty liver, glucose intolerance, insulin and leptin resistance.
View Article and Find Full Text PDFElife
July 2024
Department of Molecular and Integrative Physiology, University of Michigan-Ann Arbor, Ann Arbor, United States.
The hypothalamic ventral premammillary nucleus (PMv) is a glutamatergic nucleus essential for the metabolic control of reproduction. However, conditional deletion of leptin receptor long form (LepRb) in vesicular glutamate transporter 2 (Vglut2) expressing neurons results in virtually no reproductive deficits. In this study, we determined the role of glutamatergic neurotransmission from leptin responsive PMv neurons on puberty and fertility.
View Article and Find Full Text PDFJ Neuroendocrinol
February 2024
Centre for Neuroendocrinology, Department of Anatomy, University of Otago, Dunedin, New Zealand.
The arcuate nucleus is a crucial hypothalamic brain region involved in regulating body weight homeostasis. Neurons within the arcuate nucleus respond to peripheral metabolic signals, such as leptin, and relay these signals via neuronal projections to brain regions both within and outside the hypothalamus, ultimately causing changes in an animal's behaviour and physiology. There is a substantial amount of evidence to indicate that leptin is intimately involved with the postnatal development of arcuate nucleus melanocortin circuitry.
View Article and Find Full Text PDFJ Appl Physiol (1985)
February 2024
Department of Anesthesiology and Critical Care Medicine, George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, United States.
The carotid bodies (CBs) have been implicated in glucose abnormalities in obesity via elevation of activity of the sympathetic nervous system. Obesity-induced hypertension is mediated by insulin receptor (INSR) signaling and by leptin, which binds to the leptin receptor (LEPR) in CB and activates transient receptor potential channel subfamily M member 7 (TRPM7). We hypothesize that in mice with diet-induced obesity, hyperglycemia, glucose intolerance, and insulin resistance will be attenuated by the CB denervation (carotid sinus nerve dissection, CSND) and by knockdown of , and gene expression in CB.
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