Adenosine Activates AMPK, Increases Lactate Production and Maintains Cell Polarity in Sertoli Cells.

RIERA M FERNANDA; GALARDO MARÍA N; PELLIZZARI ELIANA H; SOBARZO CRISTIAN M; DENDUCHIS BERTA; LUSTIG LIVIA; MERONI SILVINA B; CIGORRAGA SELVA B

Washington DC, USA

Congreso; 91st Annual Meeting Endo 2009.; 2009

The Endocrine Society

Adenosine concentrations in the extracellular milieu may reach high levels as a result of ATP consumption and may constitute a message of energy deprivation for neighboring cells. Adenosine actions may result from binding to purinergic receptors but also as a result of its incorporation into the cell, transformation to AMP and activation of a specific kinase (AMPK). AMPK has been involved in re-establishing energy levels and cell polarity. The aim of this work was to analyze possible effects of adenosine on Sertoli cell (SC) function not accounted for by binding to canonical purinergic receptors but by AMPK activation. For this purpose we compared the effect on SC function of adenosine (A) and of cyclohexyladenosine (CHA), an analog which binds to the receptors but which is not transported into the cell through nucleoside transporters. Cultures of SC obtained from 20-day-old rats were stimulated with A or CHA (1 mM). Lactate production, 2-deoxyglucose (2-DOG) uptake and the glucose transporter GLUT1, the monocarboxylate transporter MCT 4 and the subunit A of lactic dehydrogenase (LDH-A) expression were analyzed. Table 1 shows that A but not CHA increased lactate production and 2-DOG uptake (mean±SD n=3 *p<0.05vs Basal). [Table 1] Lactate production (ìg/ìg DNA) 2-DOG uptake (dpm/ìg DNA) BASAL 5.4±0.4 415±21 A 48h 12.6±0.7* 620±32* CHA 48h 6.2±0.4 422±18 An increment in GLUT1, MCT4 and LDH-A mRNA levels with A but not CHA was also observed. Noticeably, Western blot analysis showed that A but not CHA increased Acetyl-CoA carboxylase phosphorylation indicating activation of AMPK. Finally, we compared the effect of A and CHA on Zonula Occludens-1 (ZO-1) distribution --a protein associated with specialized junctions-- and on transephitelial resistance (TER) in SC cultured in bicameral chambers. Cells were treated with EGTA (1.75mM) for 1h in the presence or absence of 1mM A or CHA. Extracellular Ca2+ chelation induced ZO-1 internalization. Simultaneous treatment with A but not with CHA impeded ZO-1 internalization. The effect of A was blocked by the presence of iodotubercidine (10nM) or Compound C (20ìM), inhibitors of adenosine kinase and AMPK respectively. Similarly, EGTA treatment decreased TER and A but not CHA impeded this effect. Altogether results suggest that A regulates several biochemical steps involved in lactate production and participates in the maintenance of specialized junctions utilizing an AMPK-dependent pathway in SC.Supported by CONICET Grant 5479; ANPCyT Grant 25365