Expression of the tyrosine phosphatase lar-ptp2 in rat lung is confined to proliferating epithelia lining the airways and air sacs. Kim, Hyeja, Herman Yeger, Robin Han, Megan Wallace, Barry Goldstein, and Daniela Rotin. MRC Group in Lung Development, the Hospital For Sick Children, and the Departments of Pediatrics and Clinical Biochemistry, University of Toronto, 555 University Avenue, Toronto, Ontario, M5G 1X8. (2) From the Dorrance H. Hamilton Research Laboratories, Division of Endocrinology and Metabolic Diseases, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, 1020 Locust St Philadelphia, PA, 19107
APStracts 2:0195L, 1995.
The LAR family tyrosine phosphatase LAR-PTP2B (RPTPs) was previously shown to be expressed in the central and peripheral nervous system. Here we show that LAR-PTP2, the larger alternatively spliced form of the gene, is expressed in proliferating undifferentiated lung epithelia in a developmentally regulated manner. Using in situ hybridization and parallel immunostaining with PCNA to detect proliferating cells, we demonstrate that LAR-PTP2 is expressed exclusively in the undifferentiated epithelial cell layer lining the bronchi, bronchioles and air sacs in late fetal development and in the neonatal lung. These cells correspond to Clara and fetal alveolar type II cells, as determined by parallel immunostaining with an antibodies to surfactant proteins A and B. LAR-PTP2 expression declined progressively with postnatal development, and by adult stage there was no detectible expression in the airways or in the distal (type I and II) mature non proliferating alveolar epithelial cells. These results suggest that LAR-PTP2 may be involved in the regulation of epithelial cell proliferation/differentiation during lung development.

Received 15 September 1995; accepted in final form 18 October
1995.
APS Manuscript Number L275-5.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95