1. Gene-related Sequence
Promoter activity of LTR element of the human FPRL2 gene
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Hong-seok HA, Jae-Won HUH, Dae-Soo KIM1, Heui-Soo KIM *
Division of Biological Sciences, College of Natural Sciences, Pusan National University. 
1PBBRC, Interdisciplinary Research Program of Bioinformatics, College of Natural Sciences, Pusan National University.  
ABSTRACT
INTRODUCTION
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LTR: Long Terminal Repeat
LINE: Long Integrated nuclear element
SINE: Short Integrated nuclear element
HERV: Human Endogenous Retro-Virus
The human genome is estimated to consist of approximately 8% human endogenous retroviruses (HERVs) and related sequences. FPRL2 (fomyl peptide receptor-like 2) gene has a solitary LTR (long terminal repeat). The LTR is located between first exon and promoter region of the FPRL2 gene. The FPRL2 gene containing LTR element was expressed in various human tissues except fetal brain and cerebellum. The LTR element was detected in hominoid, Old World monkeys, and New World monkeys except for common marmoset, whereas LINE (long interspersed repetitive element) and SINE (short interspersed repetitive element) elements were detected in prosimian (ring-tailed lemur) and common marmoset. We also examined promoter activity of the LTR element in FPRL2 gene, and discussed its biological role. Taken together, the insertion of retroelements into primate genome could have different biological roles during primate evolution
Other region
16%
Gene-related Sequence
36%
LINE
20%
SINE
13%
Coding sequence 3%
Pseudogene 1%
HERV element 8%
DNA element
Retroelement
RNA intermediate
- LTR element
+ LTR element
Retroposon
- env
+ env
Retrotransposon
- RT
+ RT
Yeast Ty1/copia/truncated HERVs
LTR
ORF1
ORF2
Human THE1
SINE P
Poly(A)
Human Alu
Retrovirus
Retroelements have been subjected to many amplification and transposition events resulting in a widespread distribution of complete or partial retroviral sequences throughout the human genome. The human genome comprises approximately 8% of the human endogenous retroviruses (HERVs) and other long terminal repeat (LTR)–like elements . Most HERVs seem to have entered the genome between 10 and 50 million years ago, and they comprise over 200 distinct groups and subgroups . Expression of retroelements can influence the outcome of infections in different ways that can be either beneficial or detrimental to the host. A function of the multiple copy families, scattered throughout the genome, has been reported regulatory functions on the gene expression of nearby located genes . A small minority of such sequences has acquired a role in regulating gene expression, and some of these may be related to differences between individuals, and to expression of disease
LINE
gag
pol
env
LTR
Full-length HERVs/exogenous retrovirus
ORF1
ORF2 P
Poly(A) L1
MATERIALS & METHODS
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Bioinformatics
Luciferase Assay
Transfac 6.0
Real Time RT-PCR
Bisulfite Sequencing PCR
Genomic DNA PCR
& Gene cloning
REFERENCES
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Maksakova IA, Mager DL Transcriptional regulation of early transposon elements, an active family of mouse long terminal repeat retrotransposons. J Viro
Yang D, Chen Q, Gertz B, He R, Phulsuksombati M, Ye RD, Oppenheim JJ Human dendritic cells express functional formyl peptide receptor-like-2 (FPRL2) throughout maturation. J Leukoc Biol
RESULTS & DISCUSSION
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Fig. 4. PCR analysis for the presence of LTR54-derived promoter region of FPRL2 gene using the various primate genomic DNAs (A). Primates showed PCR products that were cloned and sequenced (B,C).
Fig. 1. The genomic structure of FPRL2 gene including LTR54 element. Exons were represented by solid box with the exon numbers. Arrows indicate the primer location. The LTR54 element was integrated into the FPRL2 gene with the antisense orientation on human chromosome 19q13.41
Fig. 2. Real Time RT-PCR analysis of LTR54 derived transcript from different human tissues.
Fig. 3. Luciferase reporter gene assay for LTR54-derived promoter of FPRL2 gene in transient transfected HCT116. Relative activity of luciferase assay for pGL2-hFPRL2-LTR54 in forward and reverse orientation or the pGL2 basic vector was indicated as schematic diagram. Results are expressed as ratios of the luciferase activity to that of the promoterless pGL2 reporter plasmid.
Fig 5. Comparison of FPRL2 gene family in silico analysis; gene location (A), comparison of mRNA structure using PIP maker program(B) , alignment of amino acid (C)
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