Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rabbit lacrimal gland secretes retinol bound to a 20-21 kDa protein. To test the hypothesis that this protein might be retinol-binding protein (RBP) we probed lacrimal gland for RBP mRNA and lacrimal gland fluid for RBP. A rabbit RBP cDNA clone was used to probe rabbit and rat lacrimal gland RNA using RNase protection analysis. The lacrimal gland contains RBP mRNA at a level 0.1 to 0.03% of that observed in the liver. This RBP mRNA was identical to that observed in the liver based on RNase protection analysis, Northern blot analysis and primer extension analysis. The RBP mRNA levels in the lacrimal gland were not altered by the retinol status of the rabbits. We analysed lacrimal gland fluid for RBP by immunoblotting using a monoclonal antibody that recognizes rat, human and rabbit RBP. A single protein band from the rabbit lacrimal fluid bound the antibody, and this protein comigrated with human RBP which also bound the antibody. We conclude that the lacrimal gland contains RBP mRNA and that the lacrimal gland synthesizes and secretes RBP into the lacrimal gland fluid. This is the first demonstration that an extrahepatic tissue containing RBP mRNA synthesizes and secretes the protein in vivo.
 ...
PMID:The lacrimal gland synthesizes retinol-binding protein. 133 54

Cells that require or metabolize vitamin A contain cellular retinol-binding proteins (CRBP) and cellular retinoic acid-binding proteins (CRABP) which apparently participate in metabolism and transport of retinoids within the cell. Since the lacrimal gland secretes and metabolizes vitamin A, the cellular retinoid-binding proteins and their mRNAs should also be present in this gland. Total RNA from rat and rabbit lacrimal glands was analysed by RNase protection using 32P-labeled antisense cRNA probes. CRBP-I mRNA is present in rat lacrimal gland at 2% of the level in liver but CRBP-I mRNA could not be identified conclusively in rabbit lacrimal gland using the available rat cRNA probe. CRABP-I mRNA is present in rat lacrimal gland at 5% of the level in the 12-day gestation rat fetus, but was not detectable in the rabbit lacrimal gland. Rabbit or rat lacrimal gland cytosol was incubated with [3H]retinol or [3H] retinoic acid followed by ion-exchange chromatography using a Tris buffer and NaCl gradient. CRBP is present in rabbit and rat lacrimal gland at 78.5 +/- 14.5 and 71.1 +/- 11 pmol g-1 protein, respectively. CRABP is present in rat lacrimal gland at 190.6 +/- 13.8 pmol g-1 protein but was not detectable in rabbit lacrimal gland. The presence of CRBP in the lacrimal gland is consistent with its role in secretion of retinol into the lacrimal gland fluid. The apparent lack of CRABP in rabbit lacrimal gland as compared with rat suggests species differences in the role of retinoids in differentiation and maintenance of this organ.
 ...
PMID:Cellular retinol-binding protein and cellular retinoic acid-binding protein in the lacrimal gland. 838 4

Melanocortins (alphaMSH and ACTH-related peptides) influence the physiological functions of certain peripheral organs, including exocrine and endocrine glands. This study was designed to determine the identity and anatomical localization of the melanocortin receptors (MC-R) expressed in these organs in the rat. MC5-R messenger RNA was found in exocrine glands, including lacrimal, Harderian, preputial, and prostate glands and pancreas, as well as in adrenal gland, esophagus, and thymus, as demonstrated by ribonuclease protection assays. In exocrine glands, MC5-R messenger RNA expression was restricted to secretory epithelia. MC-R protein was likewise present in secretory epithelia of exocrine glands, as determined by 125I-labeled [Nle4,D-Phe7]alphaMSH ([125I]NDP-MSH) binding and autoradiography in tissue sections. Specific [125I]NDP-MSH binding was also observed in adrenal cortex, thymus, spleen, and esophageal and trachealis muscle. MC receptors in these sites are accessible to circulating MC-R agonists in vivo, as specific binding of [125I]NDP-MSH was observed in exocrine and adrenal glands after systemic injection in vivo. Taken together, these findings show that the MC5 receptor is commonly and selectively expressed in exocrine glands and other peripheral organs. Based on these findings and compelling evidence from other studies, a functional coherence is suggested between central and peripheral actions of melanocortins and melanocortin receptors in physiological functions, including thermoregulation, immunomodulation, and sexual behavior.
 ...
PMID:Expression of melanocortin-5 receptor in secretory epithelia supports a functional role in exocrine and endocrine glands. 956 44

Aquaporin (AQP) 5 gene was recently isolated from salivary gland and identified as a member of the AQP family. The mRNA expression and localization have been examined in several organs. The present study was focused on elucidation of AQP5 expression and localization in the eye, salivary gland, and lung in rat. RNase protection assay confirmed intense expression of AQP5 mRNA in these organs but negligible expression in other organs. To examine the mRNA expression sites in the eye, several portions were microdissected for total RNA isolation. AQP5 mRNA was enriched in cornea but not in other portions (retina, lens, iris/ciliary body, conjunctiva, or sclera). AQP5 was selectively localized on the surface of corneal epithelium in the eye by immunohistochemistry and immunoelectron microscopy using an affinity-purified anti-AQP5 antibody. AQP5 was also localized on apical membranes of acinar cells in the lacrimal gland and on the microvilli protruding into intracellular secretory canaliculi of the serous salivary gland. In the lung, apical membranes of type I pulmonary epithelial cells were also immunostained with the antibody. These findings suggest a role of AQP5 in water transport to prevent dehydration or to secrete watery products in these tissues.
 ...
PMID:Localization and expression of AQP5 in cornea, serous salivary glands, and pulmonary epithelial cells. 975 69

Type 2 cystatins comprise a class of cysteine peptidase inhibitor presumed to mediate protective functions at various locations, including the oral cavity. Seven cystatin genes are clustered within a 300-kb region of human 20p11.2. "Salivary" cystatins, encoded by CST1, 2, 4, and 5, are present in saliva at significant levels but have also been reported in other secretions, such as tears, suggesting that during their evolution, these genes have acquired mechanisms directing differential tissue-specific expression. However, their patterns of expression, which might also provide additional clues to their individual functions, have not been determined. Gene-specific RNase protection assays were used to examine the qualitative and quantitative distribution of expression of these seven genes within a collection of 23 adult human tissues. The CST3 gene, encoding cystatin C, was expressed at modest levels in all tissues examined. The presumptive pseudogenes CSTP1 and CSTP2 were not expressed at detectable levels in any tissue. The CST1, 2, 4, and 5 genes were expressed in differential, tissue-specific patterns. Expression of CST2 and CST5 was restricted to the submandibular and parotid glands, while CST1 and CST4 were expressed in these tissues and in the lacrimal gland. Immunohistochemistry studies localized expression to the serous-type secretory end pieces. Coexpression of CST1 and CST4 was also observed in the epithelial lining of the gallbladder and seminal vesicle. The CST1 product was detected in the tracheal glands and CST4 in the kidney and prostate. Despite their different adult patterns of expression, analysis of CST1, 2, 4, and 5 mRNA levels in infant submandibular glands demonstrated a coordinate upregulation of expression of between 3.5 and 9 months of age. The patterns of cystatin gene expression are consistent with several proposed oral functions of the salivary cystatins but also suggest they are important in other locations and that, despite their close sequence similarity, they are individually specialized.
 ...
PMID:Expression of type 2 cystatin genes CST1-CST5 in adult human tissues and the developing submandibular gland. 1187 80