Mj. Linke et al., SURFACTANT PHOSPHOLIPID SECRETION FROM RAT ALVEOLAR TYPE-II CELLS - POSSIBLE ROLE OF PKC ISOZYMES, American journal of physiology. Lung cellular and molecular physiology, 16(2), 1997, pp. 171-177
Protein kinase C (PKC) plays an integral role in control of many type
II cell functions, including regulation of surfactant phospholipid sec
retion. To determine which isozymes of PKC may regulate type II cell f
unctions, we identified those PKC isozymes activated in type II cells
in association with surfactant phospholipid secretion after phorbol es
ter treatment. Transcripts encoding PKC-alpha -beta, -delta, -epsilon,
-eta, and -zeta were detected in type II cells by reverse transcripta
se-polymerase chain reaction, whereas PKC-alpha, -beta, -delta, -eta,
and -zeta were detected in type II cells by immunoblotting. PKC-alpha
and -beta were only present in the cytosol in unstimulated type II cel
ls, whereas PKC isozymes delta, eta, and zeta were found in cytosol an
d membrane fractions in unstimulated type II cells. 12-O-tetradecanoyl
phorbol-13-acetate stimulated surfactant secretion and activated PKC-a
lpha, -beta, -delta, and -eta isozymes in a dose-dependent manner. The
inactive analogue 4 alpha-phorbol 12,13-didecanoate neither activated
PKC isozymes nor stimulated surfactant phospholipid secretion. PKC-ze
ta was not activated by any of the phorbol esters. PKC isozymes ct, be
ta, delta, and eta are present in purified type II epithelial cells an
d are activated in a dose-dependent manner in alveolar type II cells i
n association with surfactant phospholipid secretion after phorbol est
er treatment.