Epidermal Growth Factor Gene Expression Is Regulated Differently in Mouse Kidney and Submandibular Gland^*

Abstract

The concentration of the peptide mitogen epidermal growth factor (EGF) is hormonally and developmentally regulated in the granular convoluted tubule cells of the mouse submandibular gland. Using a labeled EGF nucleic acid probe, we have demonstrated that submandibular gland EGF mRNA concentrations increase during postnatal development of the gland and after the administration of testosterone or thyroid hormone. Recently, it was reported that EGF mRNA is present in kidney as well as a number of other mouse tissues. A comparison of EGF gene regulation in submandibular gland and kidney revealed that kidney EGF mRNA levels also increase during the postnatal period. Opposite sex differences were observed, with submandibular gland levels being about 16-fold higher in the male than in the female and kidney levels being 2- to 4-fold higher in the female than in the male. Renal EGF mRNA concentrations are less responsive to hormones than those in the submandibular gland. Renal EGF was localized immunocytochemically to the cells of distal convoluted tubules.

Effects of Long-Term Cobalamin Treatment on the Expression of the Epidermal Growth Factor System in Mouse Kidney

“…We found mRNA encoding EGF to be far more abundant in the kidney than the submaxillary gland. This is supported by another study revealing more modest differences in the expression of the EGF system [Gubits et al, 1986]. Except for EGFR, the kidney expressed the highest level of all receptors and ligands examined even in the adult mice suggesting an important physiological role.…”

Reduced Oral Wound Healing in the NOD Mouse Model for Type 1 Autoimmune Diabetes and Its Reversal by Epidermal Growth Factor Supplementation

“…The component proteins produced and released into saliva by the salivary glands are grouped according to their functions: lubrication of the oral cavity (mucins, proline-rich proteins), remineralization (statherin, proline-rich proteins), digestion (amylase, lipase, proteases), antimicrobial activity (lysozyme, peroxidases, histatins), and mucosal integrity (water, mucins, growth factors) (1)(2)(3). Biologically active growth factors include epidermal growth factor (EGF) and nerve growth factor (NGF), both of which are synthesized and secreted by the granular convoluted tubule cells of the salivary glands (4,5). Transforming growth factors ␣ and ␤ (6 -8), insulin, IGF-I and -II (9 -12), and fibroblast growth factor (13) have been localized to the ductal cells in salivary glands from which they are actively secreted into saliva.…”

“…EGF is produced in large quantities by the salivary glands and then is actively secreted in an exocrine manner into saliva (4). Injection of EGF, isolated from the submandibular gland, into neonatal mice or rats causes premature incisor eruption and precocious eyelid opening (14).…”

Salivary Epidermal Growth Factor in Mice Modulates the Differentiation of CD4CELLS in Thymus.

“…DISCUSSION EGF is capable of activating EGF receptor (EGFR or ErbB1) tyrosine kinase, which in turn activates intracellular signal transduction, enhances transcription of growth-related genes, and usually promotes cell growth and differentiation [23]. According to many workers, after sialoadenectomy the plasma EGF decreases rapidly and was undetectable by 3 weeks, indicating that the submandibular gland is a major source of circulating EGF [24] [25] [26] .After the sialoadenectomy and salivariadenectomy there was atrophy of thymus gland. The early atrophy is associated with the reduction in cortico medullary region and cellular density including decrease in CD4 thymocytes.…”