Differential regulation of alpha 2u globulin gene expression in liver, lachrymal gland, and salivary gland.

R M Gubits,K R Lynch,A B Kulkarni,K P Dolan,E W Gresik,P Hollander,P Feigelson

doi:10.1016/s0021-9258(18)90817-3

Abstract

The alpha 2u globulins, products of a highly homologous multigene family, are synthesized in the liver and submaxillary salivary glands of the rat. Although their precise function has not been ascertained, they are of interest because of the complex developmental and hormonal regulation of their tissue levels. We now report that alpha 2u globulin is synthesized in a third tissue of the rat, the extraorbital lachrymal gland. Immunocytochemical studies indicate that the distribution of alpha 2u globulin is more homogeneous in the lachrymal gland than in the liver or submaxillary gland. In situ hybridization to alpha 2u globulin RNA reveals specific signal only over the acinar cells of the lachrymal gland. Several different isoelectric forms of alpha 2u globulin are encoded by lachrymal gland mRNA. The major lachrymal and salivary gland isoforms are indistinguishable from one another, but more acidic than the hepatic isoforms. In addition, analysis of double-stranded cDNAs with a diagnostic restriction-enzyme pair detects no differences between the alpha 2u globulin mRNAs of lachrymal and salivary gland, but clearly distinguishes these from their hepatic counterparts. In spite of the similarity between the lachrymal and salivary gland alpha 2u globulin gene products, we find that the hormonal and developmental regulation of alpha 2u globulin expression differs markedly in these two tissues. In the liver, where a different subset of alpha 2u globulin genes is expressed, a third regulatory phenotype is observed.

Highlights

From the Institute of Cancer Research and Department of Biochemistryand Molecular Biophysics,College of Physicians and Surgeons, Columbia Uniuersity, New York,New York 10032 and [[DepartmentofAnatomy, Mount Sinai Schoolof Medicine of the City University of New York,New York,New York,I0024
Nalysis of double- Our present findings indicate that the regulatory phenotype stranded cDNAs with a diagnostic restriction-enzyme of lachrymal gland expression differs fromthose of both liver pair detects no differences between the a 2u globulin and submaxillary gland. a 2u globulin is found in both male mRNAs of lachrymal and salivary gland, but clearly and female lachrymal glands, but levels in the female are distinguishes these from their hepatic counterparts. lower thanthoseinthe male
In spiteof the similarity between the lachrymal andglobulin RNA increases during postnatal development, but, salivary gland a 2u globulin gene products, we find that the hormonal and developmental regulation of a 2u globulin expression differs markedly in these two tissues

Summary

Introduction

In spiteof the similarity between the lachrymal andglobulin RNA increases during postnatal development, but, salivary gland a 2u globulin gene products, we find that the hormonal and developmental regulation of a 2u globulin expression differs markedly in these two tissues. Hypophysectomy results indecreased CY 2u globulin RNA levels in the lachrymal gland, as well as the liver.

Results

Conclusion