Neurodegenerative diseases of human aging are significant US health burdens due to the growing number of people living with dementia. Many disorders like Alzheimer's disease are associated with excess brain iron that accumulates with age. Such observations have led to the metal theory of dementia, which suggests that over time, environmental exposure to iron promotes neurodegeneration. We have discovered that ?9-THC and other cannabinoids inhibit the iron transporter divalent metal transporter-1 (DMT1) through cannabinoid receptor-2 (CB2). CB2 is an immunomodulatory receptor and its anti-inflammatory neuroprotective effects confer suppression of microglia activation. Microglial cells act as the immune cells of the brain and spinal cord, becoming activated by changes in their local microenvironment. Microglia polarize between reactive and repair states to actively transition from an immune-stimulating antimicrobial phenotype to one that supports tissue repair and resolution of inflammation.
SPECIFIC AIM 1 : Determine mechanisms of microglial iron transport and metabolism. We have determined that IMG cell iron uptake corresponds to the M1/M2 activation state of IMG cells. While more non-transferrin (Tf) bound iron (NTBI) is taken up by LPS-treated cells, Tf-mediated transport is increased by IL-4. Based on our data, we hypothesize that microglial cell polarization directs iron trafficking. We will: a) Test the hypothesis that microglial cell polarization controls uptake and metabolic partitioning of iron into subcellular compartments; and b) Test the hypothesis that IMG cell activation by A? alters microglia metabolism by up- regulating DMT1 activity and dysregulating energy metabolism.
SPECIFIC AIM 2 : Determine influence of CB2 on microglial iron transport and metabolism. We have determined the CB2 selective agonist JWH102 reduces the pro-inflammatory activation state of IMG cells promoted by A?. We have also found that CB2 promotes dephosphorylation of DMT1 to block its activation. Based on our data, we hypothesize that CB2 redirects iron trafficking and cellular metabolism by regulating DMT1 phosphorylation. We will: a) Test the hypothesis that the CB2 selective agonist JWH102 reduces NTBI iron transport and shifts energy metabolism in LPS and A?-activated IMG cells; and b) Test the hypothesis that CB2 regulates DMT1 phosphorylation to control is activity in IMG cells.
The metal theory of dementia suggests that over time, environmental exposure to iron promotes neurodegeneration in diseases like Alzheimer?s disease. This project will determine how cannabinoids like ?9-THC interfere with iron uptake by Divalent Metal Transporter-1 in brain microglia, which are activated in Alzheimer?s Disease. Our study will examine the potential anti-inflammatory role of cannabinoid receptor-2 and its effects on microglial cell iron transport and metabolism.
| Wessling-Resnick, Marianne (2018) Crossing the Iron Gate: Why and How Transferrin Receptors Mediate Viral Entry. Annu Rev Nutr 38:431-458 |
| McCarthy, Ryan C; Sosa, Jose Carlo; Gardeck, Andrew M et al. (2018) Inflammation-induced iron transport and metabolism by brain microglia. J Biol Chem 293:7853-7863 |
| Grillo, Anthony S; SantaMaria, Anna M; Kafina, Martin D et al. (2017) Restored iron transport by a small molecule promotes absorption and hemoglobinization in animals. Science 356:608-616 |
| McCarthy, Ryan C; Lu, Dah-Yuu; Alkhateeb, Ahmed et al. (2016) Characterization of a novel adult murine immortalized microglial cell line and its activation by amyloid-beta. J Neuroinflammation 13:21 |
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| Alkhateeb, Ahmed A; Buckett, Peter D; Gardeck, Andrew M et al. (2015) The small molecule ferristatin II induces hepatic hepcidin expression in vivo and in vitro. Am J Physiol Gastrointest Liver Physiol 308:G1019-26 |
| Kim, Jonghan; Wessling-Resnick, Marianne (2014) Iron and mechanisms of emotional behavior. J Nutr Biochem 25:1101-1107 |
| Kim, Jonghan; Jia, Xuming; Buckett, Peter D et al. (2013) Iron loading impairs lipoprotein lipase activity and promotes hypertriglyceridemia. FASEB J 27:1657-63 |
| Jia, Xuming; Kim, Jonghan; Veuthey, Tania et al. (2013) Glucose metabolism in the Belgrade rat, a model of iron-loading anemia. Am J Physiol Gastrointest Liver Physiol 304:G1095-102 |
| Byrne, Shaina L; Krishnamurthy, Divya; Wessling-Resnick, Marianne (2013) Pharmacology of iron transport. Annu Rev Pharmacol Toxicol 53:17-36 |
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