Linked Life Data

12376335

Source:http://linkedlifedata.com/resource/pubmed/id/12376335

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2002-10-11
pubmed:abstractText
We recently demonstrated the expression of somatostatin (SS) and SS receptor (SSR) subtype 1 (sst1), sst2A, and sst3 in normal human thymic tissue and of sst1 and sst2A on isolated thymic epithelial cells (TEC). We also found an inhibitory effect of SS and octreotide on TEC proliferation. In the present study, we further investigated the presence and function of SSR in freshly purified human thymocytes at various stages of development. Thymocytes represent a heterogeneous population of lymphoid cells displaying different levels of maturation and characterized by specific cell surface markers. In this study, we first demonstrated specific high-affinity 125I-Tyr(11)-labeled SS-14 binding on thymocyte membrane homogenates. Subsequently, by RT-PCR, sst2A and sst3 mRNA expression was detected in the whole thymocyte population. After separation of thymocytes into subpopulations, we found by quantitative RT-PCR that sst2A and sst3 are differentially expressed in intermediate/mature and immature thymocytes. The expression of sst3 mRNA was higher in the intermediate/mature CD3+ fraction compared with the immature CD2+CD3- one, whereas sst2A mRNA was less abundant in the intermediate/mature CD3+ thymocytes. In 7-day-cultured thymocytes, SSR subtype mRNA expression was lost. SS-14 significantly inhibited [3H]thymidine incorporation in all thymocyte cultures, indicating the presence of functional receptors. Conversely, octreotide significantly inhibited [3H]thymidine incorporation only in the cultures of immature CD2+CD3- thymocytes. Subtype sst3 is expressed mainly on the intermediate/mature thymocyte fraction, and most of these cells generally die by apoptosis. Because SS-14, but not octreotide, induced a significant increase in the percentage of apoptotic thymocytes, it might be that sst3 is involved in this process. Moreover, sst3 has recently been demonstrated on peripheral human T lymphocytes, which derive directly from mature thymocytes, and SS analogs may induce apoptosis in these cells. Interestingly, CD14+ thymic cells, which are cells belonging to the monocyte-macrophage lineage, selectively expressed sst2A mRNA. Finally, SSR expression in human thymocytes seems to follow a developmental pathway. The heterogeneous expression of SSR within the human thymus on specific cell subsets and the endogenous production of SS as well as SS-like peptides emphasize their role in the bidirectional interactions between the main cell components of the thymus involved in intrathymic T cell maturation.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0193-1849
pubmed:author
pubmed:issnType
Print
pubmed:volume
283
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
E1056-66
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:12376335-Apoptosis, pubmed-meshheading:12376335-Cell Division, pubmed-meshheading:12376335-Cells, Cultured, pubmed-meshheading:12376335-Child, Preschool, pubmed-meshheading:12376335-Epithelial Cells, pubmed-meshheading:12376335-Gene Expression, pubmed-meshheading:12376335-Hormones, pubmed-meshheading:12376335-Humans, pubmed-meshheading:12376335-Infant, pubmed-meshheading:12376335-Iodine Radioisotopes, pubmed-meshheading:12376335-Ligands, pubmed-meshheading:12376335-Octreotide, pubmed-meshheading:12376335-RNA, Messenger, pubmed-meshheading:12376335-Receptors, Somatostatin, pubmed-meshheading:12376335-Reverse Transcriptase Polymerase Chain Reaction, pubmed-meshheading:12376335-Somatostatin, pubmed-meshheading:12376335-Thymidine, pubmed-meshheading:12376335-Thymus Gland, pubmed-meshheading:12376335-Tritium
pubmed:year
2002
pubmed:articleTitle
Quantitative and functional expression of somatostatin receptor subtypes in human thymocytes.
pubmed:affiliation
Department of Internal Medicine, Erasmus Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands. ferone@unige.it
pubmed:publicationType
Journal Article, In Vitro