title: Hormone-induced mitochondrial fission is utilized by brown adipocytes as an amplification pathway for energy expenditure.
abstract: Adrenergic stimulation of brown adipocytes (BA) induces mitochondrial uncoupling, thereby increasing energy expenditure by shifting nutrient oxidation towards thermogenesis. Here we describe that mitochondrial dynamics is a physiological regulator of adrenergically-induced changes in energy expenditure. The sympathetic neurotransmitter Norepinephrine (NE) induced complete and rapid mitochondrial fragmentation in BA, characterized by Drp1 phosphorylation and Opa1 cleavage. Mechanistically, NE-mediated Drp1 phosphorylation was dependent on Protein Kinase-A (PKA) activity, whereas Opa1 cleavage required mitochondrial depolarization mediated by FFAs released as a result of lipolysis. This change in mitochondrial architecture was observed both in primary cultures and brown adipose tissue from cold-exposed mice. Mitochondrial uncoupling induced by NE in brown adipocytes was reduced by inhibition of mitochondrial fission through transient Drp1 DN overexpression. Furthermore, forced mitochondrial fragmentation in BA through Mfn2 knock down increased the capacity of exogenous FFAs to increase energy expenditure. These results suggest that, in addition to its ability to stimulate lipolysis, NE induces energy expenditure in BA by promoting mitochondrial fragmentation. Together these data reveal that adrenergically-induced changes to mitochondrial dynamics are required for BA thermogenic activation and for the control of energy expenditure.
authors.affiliation: Department of Medicine, Boston University School of Medicine, Boston, MA, USA.
authors.forename: Jakob D
authors.initials: JD
authors.lastname: Wikstrom
authors.forename: Kiana
authors.initials: K
authors.lastname: Mahdaviani
authors.forename: Marc
authors.initials: M
authors.lastname: Liesa
authors.forename: Samuel B
authors.initials: SB
authors.lastname: Sereda
authors.forename: Yaguang
authors.initials: Y
authors.lastname: Si
authors.forename: Guy
authors.initials: G
authors.lastname: Las
authors.forename: Gilad
authors.initials: G
authors.lastname: Twig
authors.forename: Natasa
authors.initials: N
authors.lastname: Petrovic
authors.forename: Cristina
authors.initials: C
authors.lastname: Zingaretti
authors.forename: Adam
authors.initials: A
authors.lastname: Graham
authors.forename: Saverio
authors.initials: S
authors.lastname: Cinti
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Corkey
authors.forename: Barbara
authors.initials: B
authors.lastname: Cannon
authors.forename: Jan
authors.initials: J
authors.lastname: Nedergaard
authors.forename: Orian S
authors.initials: OS
authors.lastname: Shirihai
mesh_terms: D052437:Adipocytes, Brown / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D034281:Dynamins / Q000378:metabolism; D004734:Energy Metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism; D051379:Mice; D063154:Mitochondrial Dynamics / Q000187:drug effects*; D009638:Norepinephrine / Q000378:metabolism*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D059748:Proteolysis
chemical_list: D020558:GTP Phosphohydrolases; C498809:Opa1 protein, mouse; C486391:Dnm1l protein, mouse; D034281:Dynamins; D009638:Norepinephrine