ATTACHMENT OF PC12 CELLS TO ADHESION SUBSTRATUM INDUCES THE ACCUMULATION OF GLUCOSE TRANSPORTERS (GLUTS) AND STIMULATES GLUCOSE-METABOLISM

The levels of glucose transporters (GLUTs), specifically GLUT3 and GLU T1, increased dramatically in PC12 cells that were cultured on suitabl e adhesion substrate (poly-l-lysine [PLL]) and induced to differentiat e with nerve growth factor (NGF). Closer examination of this response revealed that: (1) cellular attachment to PLL was sufficient to stimul ate the increase in GLUT immunoreactivity, and (2) NGF alone was not e ffective unless the cells were cultured on PLL-treated surfaces. The r esponse to PLL was detected as early as 4 hr after plating the cells a nd peaked within 24-48 hr. Other adhesion substrata, such as collagen and poly-l-ornithine, evoked a similar response, although the latter p olymer was far less effective. The increase in GLUTs appeared to resul t from an accumulation of existing transporters because this response was not blocked by inhibiting protein synthesis. Cellular adhesion to PLL was also accompanied by a rapid activation of glucose metabolism. Thus, specific recognition of the adhesion substratum not only provide s a context for cell attachment, but also elicits important functional changes in GLUT activity.