Short- and long-term insulin-like effects of monoamine oxidases and semicarbazide-sensitive amine oxidase substrates in cultured adipocytes.
Semicarbazide-sensitive amine oxidase (SSAO) is known to increase during in vitro adipogenesis and to be one of the most highly expressed membrane proteins of white adipocytes. Although less well documented, mitochondrial monoamine oxidases (MAOs) are also present in adipocytes and share with SSAO the capacity to generate hydrogen peroxide. This work therefore aimed to compare several biologic effects of MAO and SSAO substrates in 3T3-F442A adipocytes. In differentiated cells, tyramine oxidation was predominantly MAO dependent, whereas benzylamine oxidation was SSAO dependent. Both amines partially mimicked insulin actions, including stimulation of Akt phosphorylation and glucose uptake. In addition, tyramine and benzylamine impaired tumor necrosis factor alpha-dependent nitric oxide formation in a pargyline- and semicarbazide-sensitive manner, respectively. Various biogenic amines were tested in competition for tyramine or benzylamine oxidation and classified as MAO-preferring (methoxytyramine, tryptamine) or SSAO-preferring substrates (methylamine, octopamine). Short-term incubation with 1 mmol/L of all amines except histamine stimulated glucose uptake up to 20% to 50% of maximal insulin activation. One-week treatment with either MAO or SSAO substrates alone allowed postconfluent cells to differentiate into adipocytes, reproducing 60% of insulin-promoted lipid accumulation. All amines also exerted a slight improvement in the adipogenic action of insulin. Therefore, like SSAO, substrate activation of MAO can interact with adipocyte metabolism by mimicking diverse effects of insulin in addition to preventing tumor necrosis factor alpha-dependent responses.
Carpéné
Christian
C
Institut National de la Santé et de la Recherche Médicale, U586 INSERM, IFR 31, CHU Rangueil, 31432 Toulouse cedex 4, France. carpene@toulouse.inserm.fr
Daviaud
Danièle
D
Boucher
Jeremie
J
Bour
Sandy
S
Visentin
Virgile
V
Grès
Sandra
S
Duffaut
Carine
C
Fontana
Emi
E
Testar
Xavier
X
Saulnier-Blache
Jean-Sébastien
JS
Valet
Philippe
P
D016475:3T3 Cells; D017667:Adipocytes / Q000378:metabolism*; D006631:Amine Oxidase (Copper-Containing) / Q000378:metabolism*; D000818:Animals; D001549:Benzamides / Q000378:metabolism; D001693:Biological Transport, Active; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D005947:Glucose / Q000378:metabolism; D006601:Hexoses / Q000378:metabolism; D007328:Insulin / Q000502:physiology*; D050356:Lipid Metabolism / Q000502:physiology; D008066:Lipolysis / Q000502:physiology; D051379:Mice; D008995:Monoamine Oxidase / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D010766:Phosphorylation; D048069:Tumor Necrosis Factors / Q000378:metabolism; D014439:Tyramine / Q000378:metabolism
D001549:Benzamides; D006601:Hexoses; D007328:Insulin; D009573:Nitrites; D048069:Tumor Necrosis Factors; D006631:Amine Oxidase (Copper-Containing); D008995:Monoamine Oxidase; D005947:Glucose; D014439:Tyramine