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Human dipeptidyl-peptidase I. Gene characterization, localization, and expression
1Department of Internal Medicine, Division of Respiratory, Critical Care, and Occupational Medicine, University of Utah Health Sciences Center and Veterans Administration Medical Center, Salt Lake City, Utah 84132, USA.
The Journal of Biological Chemistry
|April 11, 1997
Summary
Researchers cloned and characterized the gene for dipeptidyl-peptidase I (DPPI), a key enzyme in protein degradation and immune cell function. This study reveals its unique genomic structure and tissue-specific gene expression patterns.
Area of Science:
- Molecular Biology
- Genetics
- Enzymology
Background:
- Dipeptidyl-peptidase I (DPPI) is a lysosomal cysteine proteinase crucial for intracellular protein degradation.
- DPPI plays a central role in activating serine proteinases within immune and inflammatory cells.
- Limited knowledge exists regarding the molecular genetics and regulation of DPPI.
Purpose of the Study:
- To clone and characterize the gene encoding human dipeptidyl-peptidase I.
- To elucidate the genomic organization and chromosomal location of the DPPI gene.
- To investigate the regulatory mechanisms underlying DPPI expression, including tissue specificity and transcriptional control.
Main Methods:
- Gene cloning and characterization
- Fluorescence in situ hybridization (FISH) for gene mapping
- 5'-flanking region sequencing and analysis
- Northern blot analysis for gene expression
- Interleukin-2 treatment of lymphocytes to assess transcriptional regulation
Main Results:
- The DPPI gene spans approximately 3.5 kilobases with two exons and one intron, distinct from other papain-type cysteine proteinases.
- FISH mapped the DPPI gene to chromosomal region 11q14.1-q14.3.
- Sequence analysis revealed a GC-rich 5'-flanking region lacking classical TATA/CCAAT boxes but containing potential regulatory elements.
- Northern analyses showed high DPPI mRNA levels in lung, kidney, and placenta, with lower levels in other tissues and minimal expression in the brain.
- DPPI mRNA was highly expressed in polymorphonuclear leukocytes and alveolar macrophages.
- Interleukin-2 treatment significantly increased DPPI mRNA levels in lymphocytes, indicating transcriptional regulation.
Conclusions:
- The study provides the first detailed characterization of the human dipeptidyl-peptidase I gene, including its genomic structure and chromosomal mapping.
- The findings suggest complex tissue-specific regulation of DPPI expression, potentially mediated by identified regulatory elements in the 5'-flanking region.
- DPPI gene expression is subject to transcriptional control, as evidenced by its induction in lymphocytes upon interleukin-2 stimulation, offering insights into immune/inflammatory responses.