Cloning and expression of rat lung acidic ca++-independent
phospholipase a2 and its organ distribution.
Kim, Tae-Suk, Chandra Dodia, Xi Chen, Brian B. Hennigan, Mahendra
Jain, Sheldon I. Feinstein, and Aron B Fisher.
INSTITUTE FOR ENVIRONMENTAL MEDICINE, UNIVERSITY OF PENNSYLVANIA
SCHOOL OF MEDICINE, PHILADELPHIA, PA 19104 AND DEPARTMENT OF
CHEMISTRY AND BIOCHEMISTRY, NEWARK, DE 19716
APStracts 5:0042L, 1998.
A clone for a rat acidic Ca++-independent phospholipase A2 (aiPLA2)
was isolated from a cDNA library prepared from rat granular
pneumocytes using a probe based upon the human aiPLA2 sequence (Kim
et al., J. Biol. Chem. 272:2542-2440, 1997). In addition, a consensus
sequence for mouse aiPLA2 was constructed from several mouse cDNA
clones in the GenBank and dbEST databases. Each sequence codes for a
224-amino-acid protein with 88% identity of the amino acids among the
three species and conservation of a putative "lipase" motif
(GDSWG). Translation of mRNA produced from the rat clone in a wheat
germ system resulted in expression of PLA2 activity with similar
properties to the human enzyme, i.e., acidic pH optimum and Ca++
-independence. The localization of aiPLA2 in rat tissues was studied
using the human cDNA probe, polyclonal and monoclonal antibodies, and
aiPLA2 activity. aiPLA2 is present in lung as evidenced by high
levels of mRNA and protein expression and enzymatic activity that is
inhibited by anti-PLA2 antibody and by the transition state analogue,
1-hexadecyl-3-trifluoroethylglycero-sn-2-phosphomethanol (MJ33).
Immunocytochemistry showed the presence of aiPLA2 in alveolar type II
cells, alveolar macrophages, and bronchiolar epithelium. In brain,
heart, liver, kidney, spleen and intestine, aiPLA2 activity and mRNA
content was <50% of lung, immunoreactive protein was not
detectable, and enzymatic activity was not inhibited by MJ33 or by
aiPLA2 antibody. These results show marked enrichment of aiPLA2 in
lung compared to other organs and suggest translational control of
aiPLA2 expression.
Received 7 August 1997; accepted in final form 10 February 1998.
APS Manuscript Number L230-7.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 19 February 1998