Cooling reduces cAMP-stimulated exocytosis and adiponectin secretion at a Ca2+-dependent step in 3T3-L1 adipocytes

PLoS One. 2015 Mar 20;10(3):e0119530. doi: 10.1371/journal.pone.0119530. eCollection 2015.

Abstract

We investigated the effects of temperature on white adipocyte exocytosis (measured as increase in membrane capacitance) and short-term adiponectin secretion with the aim to elucidate mechanisms important in regulation of white adipocyte stimulus-secretion coupling. Exocytosis stimulated by cAMP (included in the pipette solution together with 3 mM ATP) in the absence of Ca2+ (10 mM intracellular EGTA) was equal at all investigated temperatures (23°C, 27°C, 32°C and 37°C). However, the augmentation of exocytosis induced by an elevation of the free cytosolic [Ca2+] to ~1.5 μM (9 mM Ca2+ + 10 mM EGTA) was potent at 32°C or 37°C but less distinct at 27°C and abolished at 23°C. Adiponectin secretion stimulated by 30 min incubations with the membrane permeable cAMP analogue 8-Br-cAMP (1 mM) or a combination of 10 μM forskolin and 200 μM IBMX was unaffected by a reduction of temperature from 32°C to 23°C. At 32°C, cAMP-stimulated secretion was 2-fold amplified by inclusion of the Ca2+ ionophore ionomycin (1μM), an effect that was not observed at 23°C. We suggest that cooling affects adipocyte exocytosis/adiponectin secretion at a Ca2+-dependent step, likely involving ATP-dependent processes, important for augmentation of cAMP-stimulated adiponectin release.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3-L1 Cells
  • 8-Bromo Cyclic Adenosine Monophosphate / analogs & derivatives
  • 8-Bromo Cyclic Adenosine Monophosphate / pharmacology
  • Adipocytes / metabolism*
  • Adiponectin / metabolism*
  • Animals
  • Calcium / metabolism*
  • Cold Temperature*
  • Cyclic AMP / metabolism*
  • Exocytosis*
  • Ionomycin / pharmacology
  • Mice
  • Models, Biological

Substances

  • Adiponectin
  • 8-Bromo Cyclic Adenosine Monophosphate
  • Ionomycin
  • 8-chloro-cyclic adenosine monophosphate
  • Cyclic AMP
  • Calcium

Grants and funding

Funding provided by Jeanssons Stiftelse, http://www.jeanssonsstiftelser.se/, Åke Wibergs Stiftelse, http://ake-wiberg.se/, Magnus Bergvalls Stiftelse, http://www.magnbergvallsstiftelse.nu/, Diabetesfonden (DIA-2011-073, DIA2012-050 and DIA2013-070), http://diabetesfonden.se/, Novonordiskfonden, http://www.novonordiskfonden.dk/en, Knut och Alice Wallenbergs Stiftelse (Dnr KAW2012.0263), https://www.wallenberg.com/kaw/, IngaBritt och Arne Lundbergs Stiftelse (Grant ID: 401), http://www.lundbergsstiftelsen.se/ and Swedish Medical Research Council (Grant IDs: 521-2012-2994 and 522-2010-2656), http://vr.se/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.