Resumo

TRIANA, Juana Ledia et al. Insulin effect in Saccharomyces cerevisiae: stimulation of pyruvate kinase activity, citoplasmatic proteins expression and cell proliferation. Rev. Soc. Ven. Microbiol. [online]. 2011, vol.31, n.1, pp.48-56. ISSN 1315-2556.

Saccharomyces cerevisiae yeast is sensitive to mammal’s insulin and acts in carbohydrate metabolism. Nevertheless, there are no studies of its effects on the glycolytic enzymes of this microorganism. This study shows that insulin stimulates pyruvate kinase activity in S. cerevisae during its growth in rich glucose supplemented media, and under aerobic conditions. In the early logarithmic phase, the maximum stimulation over control was seen in presence of 3 µM insulin (specific activity: 701 U/mg protein, 404% stimulation; absolute activity: 1.73 U/10⁶ cells, 652% stimulation), suggesting an effect over the regulation of the genetic expression of the enzyme. The presence of 1.2-3 µM of insulin stimulated the expression of cytoplasmic proteins in 51-68% and at higher concentrations (4.5-9 µM) it also stimulated cell proliferation in 25-32%, indicating cell hyperplasia and hypertrophy according to the hormone concentration in the medium. The effect of the insulin decreased in the late logarithmic growth phase, suggesting a period of action, possibly due to a nutrient dependent regulatory mechanism. This system can serve as model to study many of the molecular effects of insulin not yet known.

Palavras-chave : Saccharomyces cerevisiae; insulin; pyruvate kinase; cell proliferation.