Am. J. Respir. Cell Mol. Biol.,
Volume 21, Number 1, July, 1999 111-118
-Hexosaminidase-Induced Activation of p44/42 Mitogen-Activated
Protein Kinase Is Dependent on p21Ras and Protein Kinase C and
Mediates Bovine Airway Smooth-Muscle Proliferation
D. Betty
Lew,
B. Kinard
Dempsey,
Yuling
Zhao,
Mubarek
Muthalif,
Soghra
Fatima,
and
Kafait U.
Malik
The Crippled Children's Foundation Research Center; and Departments of Pediatrics and Pharmacology,
College of Medicine, University of Tennessee, Memphis, Tennessee
Late-phase and sustained activation of p44/42MAPK has been reported to be a critical factor in cell mitogenesis. We therefore hypothesized that p44/42MAPK is involved in mannosyl-rich glycoprotein-induced mitogenesis in bovine airway smooth-muscle cells (ASMC). Treatment of adherent ASMC with 
-hexosaminidase A (Hex A, 50 nM), an endogenous mannosyl-rich glycoprotein, resulted in a late-onset (30-min)
activation of p44/42MAPK that lasted for 4 h. Activation of p44/42MAPK induced by Hex A was inhibited by
an 18-mer phosphorothioate-derivatized antisense oligonucleotide (1-5 µM ) directed to human p44MAPK;
the mitogen-activated protein kinase kinase (MEK1) inhibitor PD98059 (5 µM); the p42MAPK inhibitor
Tyrphostin AG-126 (0.2 µM); the farnesyl transferase inhibitors SCH-56582 (10 µM) and FPT III (10 µM), which inhibit p21Ras activation; and Calphostin C (0.2 µM), an inhibitor of protein kinase C. These
agents also inhibited Hex A-induced cell proliferation in bovine ASMC. These data suggest that Hex A
activates p44/42MAPK in a p21Ras- and PKC-dependent manner and that this activation mediates Hex A-
induced mitogenesis in bovine ASMC.
