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1. Transient expression of clusterin (sulfated glycoprotein-2) during development of rat pancreas

Author

Chun Bg, M Bendayan, Jeong Sy, Kang Sw, Foster Dn, Bon Hong Min, In Sun Park, and Crabo Bg

Subjects
medicine.medical_specialty, Endocrinology, Diabetes and Metabolism, Blotting, Western, Immunocytochemistry, Gestational Age, Kidney, Rats, Sprague-Dawley, Endocrinology, Western blot, Internal medicine, Gene expression, medicine, Animals, Northern blot, Lung, Pancreas, Glycoproteins, Brain Chemistry, Complement Inactivator Proteins, Clusterin, biology, medicine.diagnostic_test, Myocardium, Embryogenesis, Brain, Heart, Embryo, Blotting, Northern, Immunohistochemistry, eye diseases, Rats, medicine.anatomical_structure, Liver, biology.protein, sense organs, Molecular Chaperones
Abstract

Clusterin has been known to play important roles not only in remodeling damaged tissues, but also in tissue reorganization during embryonic development. In the present study, we have investigated the expression of clusterin in the endocrine pancreas during embryonic development. Although a weak immunoreaction was detected in some pancreatic primordial cells at day 14 of gestation, distinct clusterin expression was identified by immunocytochemistry and Northern blot analysis at the 16th day of gestation. Clusterin-producing cells, which corresponded to insulin-containing cells, accounted for the major portion of the developing islet of Langerhans up to 18 days of gestation. Thereafter, clusterin-producing cells display similar distribution and morphological features to glucagon-producing cells. Clusterin expressed in the pancreas was shown by Western blot analysis to be a disulfide-linked heterodimer of 70 kDa with an alpha-subunit of 32 kDa. During early developmental stages, however, we found that proteolytic internal cleavage of the clusterin molecule occurred from the 18th day of gestation. Only one 70 kDa band on the 16th day and two bands (32 kDa and 70 kDa) on the 18th day of gestation were detected by Western blot analysis even in reducing conditions, while only a single 32 kDa band was detected on the second day after birth. The levels of clusterin mRNA in the pancreas transiently increased from the 16th day of gestation to the second day after birth, during the period when active cellular reorganization takes place to form the classic cellular features of the islet. Among various tissue (kidney, brain, liver, heart, lung and pancreas) the levels of clusterin mRNA were the highest in the pancreas from the 18th day of gestation to the second day after birth. In contrast, the lowest expression was observed in adult pancreatic tissue. The higher expression of clusterin in developing pancreas must indicate its involvement in tissue organization during development.

Published
1998
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3. Regulation of the cd38 promoter in human airway smooth muscle cells by TNF-alpha and dexamethasone.

Author

Tirumurugaan KG, Kang BN, Panettieri RA, Foster DN, Walseth TF, Kannan MS, Tirumurugaan, Krishnaswamy G, Kang, Bit Na, Panettieri, Reynold A, Foster, Douglas N, Walseth, Timothy F, and Kannan, Mathur S

Abstract

Background: CD38 is expressed in human airway smooth muscle (HASM) cells, regulates intracellular calcium, and its expression is augmented by tumor necrosis factor alpha (TNF-alpha). CD38 has a role in airway hyperresponsiveness, a hallmark of asthma, since deficient mice develop attenuated airway hyperresponsiveness compared to wild-type mice following intranasal challenges with cytokines such as IL-13 and TNF-alpha. Regulation of CD38 expression in HASM cells involves the transcription factor NF-kappaB, and glucocorticoids inhibit this expression through NF-kappaB-dependent and -independent mechanisms. In this study, we determined whether the transcriptional regulation of CD38 expression in HASM cells involves response elements within the promoter region of this gene.Methods: We cloned a putative 3 kb promoter fragment of the human cd38 gene into pGL3 basic vector in front of a luciferase reporter gene. Sequence analysis of the putative cd38 promoter region revealed one NF-kappaB and several AP-1 and glucocorticoid response element (GRE) motifs. HASM cells were transfected with the 3 kb promoter, a 1.8 kb truncated promoter that lacks the NF-kappaB and some of the AP-1 sites, or the promoter with mutations of the NF-kappaB and/or AP-1 sites. Using the electrophoretic mobility shift assays, we determined the binding of nuclear proteins to oligonucleotides encoding the putative cd38 NF-kappaB, AP-1, and GRE sites, and the specificity of this binding was confirmed by gel supershift analysis with appropriate antibodies.Results: TNF-alpha induced a two-fold activation of the 3 kb promoter following its transfection into HASM cells. In cells transfected with the 1.8 kb promoter or promoter constructs lacking NF-kappaB and/or AP-1 sites or in the presence of dexamethasone, there was no induction in the presence of TNF-alpha. The binding of nuclear proteins to oligonucleotides encoding the putative cd38 NF-kappaB site and some of the six AP-1 sites was increased by TNF-alpha, and to some of the putative cd38 GREs by dexamethasone.Conclusion: The EMSA results and the cd38 promoter-reporter assays confirm the functional role of NF-kappaB, AP-1 and GREs in the cd38 promoter in the transcriptional regulation of CD38. [ABSTRACT FROM AUTHOR]

Published
2008
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