Korean J Otolaryngol-Head Neck Surg.  1998 Apr;41(4):474-480.

Regulation of Mucin and Non-Mucin Secretions and Gene Expression by Retinoic Acid in Human Airway Epithelium

• Yoon JH
• Kim SS
• Park IY
• Nettesheim P

Abstract

BACKGROUND AND OBJECTIVES: Airway hypersecretion is a frequent feature of several respiratory tract diseases including rhinitis, sinusitis, and otitis media. Efforts are being made in several laboratories to elucidate mechanisms involved in the regulation of secretion. There are several factors which modulate expression of the secretory phenotype, such as retinoic acid (RA), triiodothyronine, steroid, and extracellular matrix. We have been interested in elucidating the role of retinoids in regulating differentiation of mucin and non-mucin secretions.
MATERIALS AND METHODS
Retinoic acid was removed from the culture media of normal human tracheobronchial epithelial cells grown in the air-liquid interface cultures. The effects on cell phenotype and mucin, lysozyme (LZ), and the secretory leukocyte protease inhibitor (SLPI) secretion and gene expression were examined.
RESULTS
Removal of RA from the media induced squamous differentiation and caused a drastic decrease in mucin secretion and a decrease in expression of the mucin genes, MUC2 and MUC5AC. Lysozyme and SLPI secretions were increased in RA-depleted cultures. Paradoxically, LZ mRNA was decreased, while the SLPI mRNA levels were increased. A most intriguing finding was the paradoxical response of LZ to RA-depletion. The reason for this apparant incongruity between mRNA and protein levels is currently under investigation.
CONCLUSION
Our studies show that RA is an important factor for mucous differentiation.

Keyword

Mucin; Lysozyme; SLPI; Human airway epithelium

MeSH Terms

Culture Media
Epithelial Cells
Epithelium*
Extracellular Matrix
Gene Expression*
Humans*
Mucins*
Muramidase
Otitis Media
Phenotype
Respiratory Tract Diseases
Retinoids
Rhinitis
RNA, Messenger
Secretory Leukocyte Peptidase Inhibitor
Sinusitis
Tretinoin*
Triiodothyronine
Culture Media
Mucins
Muramidase
RNA, Messenger
Retinoids
Secretory Leukocyte Peptidase Inhibitor
Tretinoin
Triiodothyronine