Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The components of the insulin-like growth factor (IGF) axis have been investigated in the normal human thymus. Using ribonuclease protection assays (RPA), IGF-II transcripts were detected in the normal human thymus. By reverse transcriptase polymerase chain reaction (RT-PCR) analyses, promoters P3 and P4 were found to be active in the transcription of IGF2 gene within human thymic epithelial cells (TEC). No IGF-II mRNA could be detected in human lymphoid Jurkat T cells with 30 cycles of RT-PCR. By Northern blot analyses, IGFBP-2 to -6 (but not IGFBP-1) were found to be expressed in TEC with a predominance of IGFBP-4. Interestingly, Jurkat T cells only express IGFBP-2 but at high levels. The type 1 IGF receptor was detected in Jurkat T cells but not in human TEC. The identification of the components of the IGF axis within separate compartments of the human thymus adds further evidence for a role of this axis in the control of T-cell development. The precise influence of thymic IGF axis upon T-cell differentiation and immunological self-tolerance however needs to be further investigated.
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PMID:Characterization of the insulin-like growth factor axis in the human thymus. 1033 24

The human insulin-like growth factor-II (IGF2) is a regulatory peptide which is critical in normal fetal growth. IGF2 gene transcription is controlled by the usage of four promoters P1-P4 of which promoters P2-P4 are genomically imprinted. Disruption of imprinting and the resulting increase of gene dosage have been shown to be implicated in tumor progression in a variety of human tumors. Due to the need for high amounts of tissue material for conventional methods such as Northern blotting or ribonuclease protection assay (RPA), studies on IGF2 expression have most often been limited to the detection of total IGF2 transcript, though different dysregulatory events can be responsible for the abundance of IGF2 mRNA found in many tumors. We established a highly sensitive competitive RT-PCR assay for the four different transcripts of the IGF2 gene with transcript-specific external RNA competitors in which we take advantage of fluorescence-based quantification on a semiautomated sequencer. The amount of total RNA needed is approximately 100 times lower than the amounts required for Northern blotting or RPA, so that even cytological samples can be analyzed. We applied the assay to a series of eleven hepatoblastomas (HB) in which normal adjacent liver tissue could also be analyzed.
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PMID:Promoter-specific transcription of the IGF2 gene: a novel rapid, non-radioactive and highly sensitive protocol for mRNA analysis. 1178 54