Genomic structure, organization and promoter analysis of the human F11R/F11 receptor/junctional adhesion molecule-1/JAM-A

Junctional Adhesion Molecules: Potential Proteins in Atherosclerosis

Junctional adhesion molecules (JAMs) are cell-cell adhesion molecules of the immunoglobulin superfamily and are involved in the regulation of diverse atherosclerosis-related processes such as endothelial barrier maintenance, leucocytes transendothelial migration, and angiogenesis. To combine and further broaden related results, this review concluded the recent progress in the roles of JAMs and predicted future studies of JAMs in the development of atherosclerosis.

The F11 Receptor (F11R)/Junctional Adhesion Molecule-A (JAM-A) (F11R/JAM-A) in cancer progression

The F11 Receptor (F11R), also called Junctional Adhesion Molecule-A (JAM-A) (F11R/JAM-A), is a transmembrane glycoprotein of the immunoglobulin superfamily, which is mainly located in epithelial and endothelial cell tight junctions and also expressed on circulating platelets and leukocytes. It participates in the regulation of various biological processes, as diverse as paracellular permeability, tight junction formation and maintenance, leukocyte transendothelial migration, epithelial-to-mesenchymal transition, angiogenesis, reovirus binding, and platelet activation. Dysregulation of F11R/JAM-A may result in pathological consequences and disorders in normal cell function. A growing body of evidence points to its role in carcinogenesis and invasiveness, but its tissue-specific pro- or anti-tumorigenic role remains a debated issue. The following review focuses on the F11R/JAM-A tissue-dependent manner in tumorigenesis and metastasis and also discusses the correlation between poor patient clinical outcomes and its aberrant expression. In the future, it will be required to clarify the signaling pathways that are activated or suppressed via the F11R/JAM-A protein in various cancer types to understand its multiple roles in cancer progression and further use it as a novel direct target for cancer treatment.

Development of new antiatherosclerotic and antithrombotic drugs utilizing F11 receptor (F11R/JAM-A) peptides

Peptides with enhanced resistance to proteolysis, based on the amino acid sequence of the F11 receptor molecule (F11R, aka JAM-A/Junctional adhesion molecule-A), were designed, prepared, and examined as potential candidates for the development of anti-atherosclerotic and anti-thrombotic therapeutic drugs. A sequence at the N-terminal of F11R together with another sequence located in the first Ig-loop of this protein, were identified to form a steric active-site operating in the F11R-dependent adhesion between cells that express F11R molecules on their external surface. In silico modeling of the complex between two polypeptide chains with the sequences positioned in the active-site was used to generate peptide-candidates designed to inhibit homophilic interactions between surface-located F11R molecules. The two lead F11R peptides were modified with D-Arg and D-Lys at selective sites, for attaining higher stability to proteolysis in vivo. Using molecular docking experiments we tested different conformational states and the putative binding affinity between two selected D-Arg and D-Lys-modified F11R peptides and the proposed binding pocket. The inhibitory effects of the F11R peptide 2HN-(dK)-SVT-(dR)-EDTGTYTC-CONH2 on antibody-induced platelet aggregation and on the adhesion of platelets to cytokine-inflammed endothelial cells are reported in detail, and the results point out the significant potential utilization of F11R peptides for the prevention and treatment of atherosclerotic plaques and associated thrombotic events.

Ultrasound-guided imaging of junctional adhesion molecule-A-targeted microbubbles identifies vulnerable plaque in rabbits

Identification of vulnerable atherosclerotic plaques by imaging the molecular characteristics is intensively studied recently, in which verification of specific markers is the critical step. JAM-A, a junctional membrane protein, is involved in the plaque formation, while it is unknown whether it can serve as a marker for vulnerable plaques. Vulnerable and stable plaques were created in rabbits with high cholesterol diet with or without partial ligation of carotid artery respectively. Significant higher JAM-A expression was found in vulnerable plaques than that in stable plaques. Furthermore, JAM-A was not only expressed in the endothelium, but also abundantly expressed in CD68-positive area. Next, JAM-A antibody conjugated microbubbles (MBJAM-A) or control IgG-conjugated microbubbles (MBC) were developed by conjugating the biotinylated antibodies to the streptavidin modified microbubbles, and visualization by contrast-enhance ultrasound (CEUS). Signal intensity of MBJAM-A was substantially enhanced and prolonged in the vulnerable plaque and some of the MBJAM-A was found colocalized with CD68 positive macrophages. In addition, cell model revealed that MBJAM-A were able to be phagocytized by activated macrophages. Taken together, we have found that increase of JAM-A serves as a marker for vulnerable plaques and targeted CEUS would be possibly a novel non-invasive molecular imaging method for plaque vulnerability.

Junctional proteins of the blood-brain barrier: New insights into function and dysfunction

The blood-brain barrier (BBB) is a highly complex and dynamic barrier. It is formed by an interdependent network of brain capillary endothelial cells, endowed with barrier properties, and perivascular cells (astrocytes and pericytes) responsible for inducing and maintaining those properties. One of the primary properties of the BBB is a strict regulation of paracellular permeability due to the presence of junctional complexes (tight, adherens and gap junctions) between the endothelial cells. Alterations in junction assembly and function significantly affect BBB properties, particularly barrier permeability. However, such alterations are also involved in remodeling the brain endothelial cell surface and regulating brain endothelial cell phenotype. This review summarizes the characteristics of brain endothelial tight, adherens and gap junctions and highlights structural and functional alterations in junctional proteins that may contribute to BBB dysfunction.

F11R mRNA expression and promoter polymorphisms in patients with rheumatoid arthritis

AIM

Although F11 receptor (F11R), also named junctional adhesion molecular A (JAM-A), participates in leukocyte migration, its role in autoimmune diseases has not been specifically disclosed. In this study, we examined the association of F11R expression with the development and clinical manifestations of rheumatoid arthritis (RA).

METHOD

RNA from peripheral blood mononuclear cells (PBMCs) and DNA from the peripheral blood in RA patients and a healthy control group were extracted. F11R messenger RNA (mRNA) expression was determined by quantitative real-time polymerase chain reaction. The F11R polymorphisms were determined by the TaqMan genotyping assay.

RESULTS

There was more F11R mRNA expression in the PBMCs of RA patients than those of the control group (P = 0.018). In F11R promoter -688 A > C, C carriers have lower titers of the anticyclic citrullinated peptide (anti-CCP) antibodies (P = 0.002) and fewer positive rates of Schirmer's tests (P = 0.009). The effect is independent of the existence of HLA-DR4. Different genotypes in F11R promoter -688 A > C and -436 A > G do not lead to changes of the gene expression in RA patients.

CONCLUSION

RA patients have higher mRNA expression of F11R. In RA patients, F11R -688 C may be a protective factor for the development of anti-CCP antibodies and positive rates of Schirmer's tests.

Transcriptome-based identification of new anti-inflammatory and vasodilating properties of the n-3 fatty acid docosahexaenoic acid in vascular endothelial cell under proinflammatory conditions [corrected]

Scope

High intakes of n-3 fatty acids exert anti-inflammatory effects and cardiovascular protection, but the underlying molecular basis is incompletely defined. By genome-wide analysis we searched for novel effects of docosahexaenoic acid (DHA) on gene expression and pathways in human vascular endothelium under pro-inflammatory conditions.

Methods and Results

Human umbilical vein endothelial cells were treated with DHA and then stimulated with interleukin(IL)-1β. Total RNA was extracted, and gene expression examined by DNA microarray. DHA alone altered the expression of 188 genes, decreasing 92 and increasing 96. IL-1β changed the expression of 2031 genes, decreasing 997 and increasing 1034. Treatment with DHA before stimulation significantly affected the expression of 116 IL-1β-deregulated genes, counter-regulating the expression of 55 genes among those decreased and of 61 among those increased. Functional and network analyses identified immunological, inflammatory and metabolic pathways as the most affected. Newly identified DHA-regulated genes are involved in stemness, cellular growth, cardiovascular system function and cancer, and included cytochrome p450 4F2(CYP4F2), transforming growth factor(TGF)-β2, Cluster of Differentiation (CD)47, caspase recruitment domain(CARD)11 and phosphodiesterase(PDE)5α.

Conclusions

Endothelial exposure to DHA regulates novel genes and related pathways. Such unbiased identification should increase our understanding of mechanisms by which n-3 fatty acids affect human diseases.

The functional role of long non-coding RNAs and epigenetics

Long non-coding RNAs (lncRNAs) are non-protein coding transcripts longer than 200 nucleotides. The post-transcriptional regulation is influenced by these lncRNAs by interfering with the microRNA pathways, involving in diverse cellular processes. The regulation of gene expression by lncRNAs at the epigenetic level, transcriptional and post-transcriptional level have been well known and widely studied. Recent recognition that lncRNAs make effects in many biological and pathological processes such as stem cell pluripotency, neurogenesis, oncogenesis and etc. This review will focus on the functional roles of lncRNAs in epigenetics and related research progress will be summarized.

Inhibition of junctional adhesion molecule-A/LFA interaction attenuates leukocyte trafficking and inflammation in brain ischemia/reperfusion injury

Proinflammatory mediators trigger intensive postischemic inflammatory remodeling of the blood-brain barrier (BBB) including extensive brain endothelial cell surface and junctional complex changes. Junctional adhesion molecule-A (JAM-A) is a component of the brain endothelial junctional complex with dual roles: paracellular route occlusion and regulating leukocyte docking and migration. The current study examined the contribution of JAM-A to the regulation of leukocyte (neutrophils and monocytes/macrophages) infiltration and the postischemic inflammatory response in brain ischemia/reperfusion (I/R injury). Brain I/R injury was induced by transient middle cerebral artery occlusion (MCAO) for 30min in mice followed by reperfusion for 0-5days, during which time JAM-A antagonist peptide (JAM-Ap) was administered. The peptide, which inhibits JAM-A/leukocyte interaction by blocking the interaction of the C2 domain of JAM-A with LFA on neutrophils and monocytes/macrophages, attenuated I/R-induced neutrophil and monocyte infiltration into brain parenchyma. Consequently, mice treated with JAM-A peptide during reperfusion had reduced expression (~3-fold) of inflammatory mediators in the ischemic penumbra, reduced infarct size (94±39 vs 211±38mm3) and significantly improved neurological score. BBB hyperpermeability was also reduced. Collectively, these results indicate that JAM-A has a prominent role in regulating leukocyte infiltration after brain I/R injury and could be a new target in limiting post-ischemic inflammation.

Upregulation of junctional adhesion molecule-A is a putative prognostic marker of hypertension

Aims

Establishing biochemical markers of pre-hypertension and early hypertension could help earlier diagnostics and therapeutic intervention. We assess dynamics of junctional adhesion molecule-A (JAM-A) expression in rat models of hypertension and test whether JAM-A expression could be driven by angiotensin (ANG) II and whether JAM-A contributes to the progression of hypertension. We also compare JAM-A expression in normo- and hypertensive humans.

Methods and results

In pre-hypertensive and spontaneously hypertensive rats (SHRs), JAM-A protein was overexpressed in the brainstem microvasculature, lung, liver, kidney, spleen, and heart. JAM-A upregulation at early and late stages was even greater in the stroke-prone SHR. However, JAM-A was not upregulated in leucocytes and platelets of SHRs. In Goldblatt 2K-1C hypertensive rats, JAM-A expression was augmented before any increase in blood pressure, and similarly JAM-A upregulation preceded hypertension caused by peripheral and central ANG II infusions. In SHRs, ANG II type 1 (AT₁) receptor antagonism reduced JAM-A expression, but the vasodilator hydralazine did not. Body-wide downregulation of JAM-A with Vivo-morpholinos in juvenile SHRs delayed the progression of hypertension. In the human saphenous vein, JAM-A mRNA was elevated in hypertensive patients with untreated hypertension compared with normotensive patients but reduced in patients treated with renin–angiotensin system antagonists.

Conclusion

Body-wide upregulation of JAM-A in genetic and induced models of hypertension in the rat precedes the stable elevation of arterial pressure. JAM-A upregulation may be triggered by AT₁ receptor-mediated signalling. An association of JAM-A with hypertension and sensitivity to blockers of ANG II signalling were also evident in humans. We suggest a prognostic and possibly a pathogenic role of JAM-A in arterial hypertension.

Relocalization of junctional adhesion molecule A during inflammatory stimulation of brain endothelial cells

Junctional adhesion molecule A (JAM-A) is a unique tight junction (TJ) transmembrane protein that under basal conditions maintains endothelial cell-cell interactions but under inflammatory conditions acts as a leukocyte adhesion molecule. This study investigates the fate of JAM-A during inflammatory TJ complex remodeling and paracellular route formation in brain endothelial cells. The chemokine (C-C motif) ligand 2 (CCL2) induced JAM-A redistribution from the interendothelial cell area to the apical surface, where JAM-A played a role as a leukocyte adhesion molecule participating in transendothelial cell migration of neutrophils and monocytes. JAM-A redistribution was associated with internalization via macropinocytosis during paracellular route opening. A tracer study with dextran-Texas Red indicated that internalization occurred within a short time period (~10 min) by dextran-positive vesicles and then became sorted to dextran-positive/Rab34-positive/Rab5-positive vesicles and then Rab4-positive endosomes. By ~20 min, most internalized JAM-A moved to the brain endothelial cell apical membrane. Treatment with a macropinocytosis inhibitor, 5-(N-ethyl-N-isopropyl)amiloride, or Rab5/Rab4 depletion with small interfering RNA oligonucleotides prevented JAM-A relocalization, suggesting that macropinocytosis and recycling to the membrane surface occur during JAM-A redistribution. Analysis of the signaling pathways indicated involvement of RhoA and Rho kinase in JAM-A relocalization. These data provide new insights into the molecular and cellular mechanisms involved in blood-brain barrier remodeling during inflammation.

Transcription and translation of human F11R gene are required for an initial step of atherogenesis induced by inflammatory cytokines

BACKGROUND

The F11 Receptor (F11R; aka JAM-A, JAM-1) is a cell adhesion protein present constitutively on the membrane surface of circulating platelets and within tight junctions of endothelial cells (ECs). Previous reports demonstrated that exposure of ECs to pro-inflammatory cytokines causes insertion of F11R molecules into the luminal surface of ECs, ensuing with homologous interactions between F11R molecules of platelets and ECs, and a resultant adhesion of platelets to the inflamed ECs. The main new finding of the present report is that the first step in this chain of events is the de-novo transcription and translation of F11R molecules, induced in ECs by exposure to inflammatory cytokines.

METHODS

The experimental approach utilized isolated, washed human platelet suspensions and cultured human venous endothelial cells (HUVEC) and human arterial endothelial cells (HAEC) exposed to the proinflammatory cytokines TNF-alpha and/or IFN-gamma, for examination of the ability of human platelets to adhere to the inflamed ECs thru the F11R. Our strategy was based on testing the effects of the following inhibitors on this activity: general mRNA synthesis inhibitors, inhibitors of the NF-kappaB and JAK/STAT pathways, and small interfering F11R-mRNA (siRNAs) to specifically silence the F11R gene.

RESULTS

Treatment of inflamed ECs with the inhibitors actinomycin, parthenolide or with AG-480 resulted in complete blockade of F11R- mRNA expression, indicating the involvement of NF-kappaB and JAK/STAT pathways in this induction. Transfection of ECs with F11R siRNAs caused complete inhibition of the cytokine-induced upregulation of F11R mRNA and inhibition of detection of the newly- translated F11R molecules in cytokine-inflamed ECs. The functional consequence of the inhibition of F11R transcription and translation was the significant blockade of the adhesion of human platelets to inflamed ECs.

CONCLUSION

These results prove that de novo synthesis of F11R in ECs is required for the adhesion of platelets to inflamed ECs. Because platelet adhesion to an inflamed endothelium is crucial for plaque formation in non-denuded blood vessels, we conclude that the de-novo translation of F11R is a crucial early step in the initiation of atherogenesis, leading to atherosclerosis, heart attacks and stroke.

Brain endothelial cell-cell junctions: how to "open" the blood brain barrier

The blood-brain barrier (BBB) is a highly specialized structural and biochemical barrier that regulates the entry of blood-borne molecules into brain, and preserves ionic homeostasis within the brain microenvironment. BBB properties are primarily determined by junctional complexes between the cerebral endothelial cells. These complexes are comprised of tight and adherens junctions. Such restrictive angioarchitecture at the BBB reduces paracellular diffusion, while minimal vesicle transport activity in brain endothelial cells limits transcellular transport. Under normal conditions, this largely prevents the extravasation of large and small solutes (unless specific transporters are present) and prevents migration of any type of blood-borne cell. However, this is changed in many pathological conditions. There, BBB disruption (“opening”) can lead to increased paracellular permeability, allowing entry of leukocytes into brain tissue, but also contributing to edema formation. In parallel, there are changes in the endothelial pinocytotic vesicular system resulting in the uptake and transfer of fluid and macromolecules into brain parenchyma. This review highlights the route and possible factors involved in BBB disruption in a variety of neuropathological disorders (e.g. CNS inflammation, Alzheimer’s disease, Parkinson’s disease, epilepsy). It also summarizes proposed signal transduction pathways that may be involved in BBB “opening”.

Association of F11 receptor gene polymorphisms with central obesity and blood pressure

OBJECTIVES

F11 receptor, also known as junctional adhesion molecule-1, in the autonomic nervous system is implicated in the development of hypertension in spontaneous hypertensive rats. We investigated the association of single nucleotide polymorphisms (SNPs) in the F11 receptor gene (F11R) with hypertension and central obesity in Hong Kong Chinese.

METHODS

Seven tagging SNPs were identified in the HapMap database. Genotyping was performed using Sequenom MassArray in 263 hypertensive subjects and 393 normotensive controls, of whom 263 matched the cases in age and sex.

RESULTS

When subjects on anti-hypertensive medication were excluded, rs790056 and rs2774276 were associated with lower systolic blood pressure (TT:124.8 +/- 18.3 mmHg vs. TC + CC: 120.2 +/- 15.5 mmHg, P = 0.004 and CC: 124.7 +/- 18.5 mmHg vs. CG+GG: 120.5 +/- 15.1 mmHg, P = 0.007 respectively). Comparing 213 subjects with central obesity with 213 controls matched for sex and age, rs2481084 and rs3737787 were associated with lower odds of central obesity (odds ratio = 0.516, P = 0.002 and odds ratio = 0.540, P = 0.005 respectively). All these associations remained significant after correction for multiple testing. Analysis of statistically similar SNPs suggested that the causative variants for systolic blood pressure were located in F11R, whilst those for central obesity could be due to causative variants in the transcription factor 1 gene immediately upstream.

CONCLUSIONS

F11 receptor plays a role in blood pressure regulation, not only in rats but also in man. The link between F11 receptor and central obesity merits further investigation.

Expression of CLMP, a novel tight junction protein, is mediated via the interaction of GATA with the Kruppel family proteins, KLF4 and Sp1, in mouse TM4 Sertoli cells

Regulation of tight junction protein expressions in Sertoli cells is important for germ cell translocation across the blood-testis-barrier (BTB) during spermatogenesis. In this study, a novel tight junction transmembrane protein, CLMP, found expressed in mouse testis was shown to localize at the BTB along with the tight junction marker ZO-1. By the use of transient transfection assay performed in a mouse Sertoli cell-cell line, TM4 cells, we showed that the minimal CLMP promoter was located between nucleotides -550 and -288 relative to the translation start site. Site-directed mutagenic studies showed that three motifs, namely GATA, KLF4, and SRY, within this region functionally co-operated with one another to regulate CLMP gene transcription. Using specific antibodies in EMSA analysis, a ternary protein complex GATA-1/GATA-6/KLF4 was detected at all the three motifs, suggesting that a looping mechanism might involve in regulating CLMP gene transcription. Interestingly, the ubiquitously expressed transcription factors, Sp1 and Sp3, were also found in this ternary complex over the KLF4 motif. Overexpression of KLF4 significantly increased the promoter activity whilst overexpression of Sp1 or Sp3 exerted an opposite effect. In particular, co-transfection studies showed that Sp1 could significantly abolish the KLF4-induced transactivation of the CLMP gene, suggesting that KLF4 and Sp1 might compete for the same binding site on the CLMP promoter. Taken together, this differential interaction of the transcription factors, GATA-1, GATA-6, KLF4, Sp1, and Sp3, in CLMP gene expression might provide a precise machinery in regulating Sertoli cell tight junction dynamics.

Gene expression changes induced by the tumorigenic pyrrolizidine alkaloid riddelliine in liver of Big Blue rats

Background

Pyrrolizidine alkaloids (PAs) are probably the most common plant constituents that poison livestock, wildlife, and humans worldwide. Riddelliine is isolated from plants grown in the western United States and is a prototype of genotoxic PAs. Riddelliine was used to investigate the genotoxic effects of PAs via analysis of gene expression in the target tissue of rats in this study. Previously we observed that the mutant frequency in the liver of rats gavaged with riddelliine was 3-fold higher than that in the control group. Molecular analysis of the mutants indicated that there was a statistically significant difference between the mutational spectra from riddelliine-treated and control rats.

Results

Riddelliine-induced gene expression profiles in livers of Big Blue transgenic rats were determined. The female rats were gavaged with riddelliine at a dose of 1 mg/kg body weight 5 days a week for 12 weeks. Rat whole genome microarray was used to perform genome-wide gene expression studies. When a cutoff value of a two-fold change and a P-value less than 0.01 were used as gene selection criteria, 919 genes were identified as differentially expressed in riddelliine-treated rats compared to the control animals. By analysis with the Ingenuity Pathway Analysis Network, we found that these significantly changed genes were mainly involved in cancer, cell death, tissue development, cellular movement, tissue morphology, cell-to-cell signaling and interaction, and cellular growth and proliferation. We further analyzed the genes involved in metabolism, injury of endothelial cells, liver abnormalities, and cancer development in detail.

Conclusion

The alterations in gene expression were directly related to the pathological outcomes reported previously. These results provided further insight into the mechanisms involved in toxicity and carcinogenesis after exposure to riddelliine, and permitted us to investigate the interaction of gene products inside the signaling networks.

Transcriptional regulation of MICA and MICB: a novel polymorphism in MICB promoter alters transcriptional regulation by Sp1

MHC class I-related genes A/B (MICA/B) are ligands of the NKG2D receptor expressed on T and NK cells. Their expression is highly restricted in normal tissues, but is up-regulated in tumoral and infected cells. We show that the minimal promoter of both genes contains a CCAAT box, which binds to NF-Y, and a GC box, which binds to Sp1, Sp3 and Sp4. We also demonstrate that MICB promoter is polymorphic, showing three single nucleotide polymorphisms (C>G at +16, -341, -408) and a deletion of two base pairs at -66 (AG>--) that is located close to the CCAAT box (-70) and the GC box (-86). Transcriptional activity associated with MICB promoter variants carrying this deletion, present in the 45.3% of Spanish population, showed a remarkable decrease (18-fold, p <0.01). By functional analysis, we show that the deletion plays a critical role in MICB promoter activity by diminishing Sp1 transcriptional activation. These important variations in MICB expression among normal individuals could imply a significant difference in the natural immune response against infections or tumor transformation, and might thereby contribute to an increased aberrant immune response against self cells, providing the molecular basis for the associations of the MICB gene to different autoimmune diseases.

Revised genomic structure of the human ghrelin gene and identification of novel exons, alternative splice variants and natural antisense transcripts

Background

Ghrelin is a multifunctional peptide hormone expressed in a range of normal tissues and pathologies. It has been reported that the human ghrelin gene consists of five exons which span 5 kb of genomic DNA on chromosome 3 and includes a 20 bp non-coding first exon (20 bp exon 0). The availability of bioinformatic tools enabling comparative analysis and the finalisation of the human genome prompted us to re-examine the genomic structure of the ghrelin locus.

Results

We have demonstrated the presence of an additional novel exon (exon -1) and 5' extensions to exon 0 and 1 using comparative in silico analysis and have demonstrated their existence experimentally using RT-PCR and 5' RACE. A revised exon-intron structure demonstrates that the human ghrelin gene spans 7.2 kb and consists of six rather than five exons. Several ghrelin gene-derived splice forms were detected in a range of human tissues and cell lines. We have demonstrated ghrelin gene-derived mRNA transcripts that do not code for ghrelin, but instead may encode the C-terminal region of full-length preproghrelin (C-ghrelin, which contains the coding region for obestatin) and a transcript encoding obestatin-only. Splice variants that differed in their 5' untranslated regions were also found, suggesting a role of these regions in the post-transcriptional regulation of preproghrelin translation. Finally, several natural antisense transcripts, termed ghrelinOS (ghrelin opposite strand) transcripts, were demonstrated via orientation-specific RT-PCR, 5' RACE and in silico analysis of ESTs and cloned amplicons.

Conclusion

The sense and antisense alternative transcripts demonstrated in this study may function as non-coding regulatory RNA, or code for novel protein isoforms. This is the first demonstration of putative obestatin and C-ghrelin specific transcripts and these findings suggest that these ghrelin gene-derived peptides may also be produced independently of preproghrelin. This study reveals several novel aspects of the ghrelin gene and suggests that the ghrelin locus is far more complex than previously recognised.

Regulation of alpha-synuclein expression in alcohol-preferring and -non preferring rats

The alpha-synuclein (Snca) gene is expressed at higher levels in alcohol-naïve, inbred alcohol-preferring (iP) rats than in alcohol-non preferring (iNP) rats. Snca modulates dopamine transmission and the dopamineregic system, which play a role in mediating the rewarding properties of alcohol consumption. Thus, understanding regulation of Snca gene expression could provide insight into the relationship of Snca and alcohol consumption. To study regulation of rat Snca expression, 1,912 bp of the iP and iNP 5'-regions were cloned and sequenced. 5'-rapid amplification of cDNA ends (RACE), primer extension and RT-PCR mapped three transcription start site clusters (clusters TSS1, TSS2 and TSS3), suggesting that the Snca proximal promoter region has a complex architecture. This proximal promoter region has three TATA-less core promoters containing SP1 binding sites, initiator elements and downstream core promoter elements, which are often located in such promoters. Snca-luc constructs transiently transfected into SK-N-SH neuroblastoma cells showed that the region from - 1,912 to - 1,746 contained a strong core promoter, and that the entire approximately 2 kb region had significant promoter activity. Five polymorphisms identified between the iP and iNP in the proximal promoter region did not influence differential expression between the strains. In contrast, a single nucleotide polymorphism (SNP) at + 679 in the 3'-untranslated region (UTR) resulted in a 1.3-fold longer half-life of iP mRNA compared with iNP mRNA, which is consistent with the differential expression observed between the iP and iNP strains. These results suggest that regulation of rat Snca gene expression is complex and may contribute to alcohol preference in the iP rats.

Isolation, sequencing, and functional analysis of the TATA-less murine ATPase II promoter and structural analysis of the ATPase II gene

The P-type Mg2+-ATPase, termed ATPase II (Atp8a1), is a putative aminophospholipid transporting enzyme, which helps to maintain phospholipid asymmetry in cell membranes. In this project we have elucidated the organization of the mouse ATPase II gene and identified its promoter. Located within chromosome 5, this gene spans about 224 kb and consists of 38 exons, three of which are alternatively spliced (exons 7, 8 and 16), giving rise to two transcript variants. Translation of these transcripts results in two ATPase II isoforms (1 and 2) composed of 1164 and 1149 amino acids, respectively. Using RNA ligase-mediated rapid amplification of cDNA ends (RLM-RACE) we identified multiple transcription start sites (TSS) in messages obtained from heart, lung, liver, and spleen. The mouse ATPase II promoter is TATA-less and lacks a consensus initiator sequence. Luciferase reporter analysis of full and core promoters revealed strong activity and little cell type specificity, possibly because more flanking, regulatory sequences are required to cause such tissue specificity. In the neuronal HN2, N18, SN48 cells and the NIH3T3 fibroblast cells, but not in the B16F10 melanoma cells, the core promoter (-318/+193 with respect to the most common TSS) displayed significantly higher activity than the full promoter (-1026/+193). Serial 5' deletion of the core promoter revealed significant cell type-specific activity of the fragments, suggesting differential expression and use of transcription factors in the five cell lines tested. Additionally distribution of the TSS was organ specific. Such observations suggest tissue-specific differences in transcription initiation complex assembly and regulation of ATPase II gene expression. Information presented here form the groundwork for further studies on the expression of this gene in apoptotic cells.

Cell-cell adhesion in lung endothelium

Homotypic cell-cell adhesion is essential for tissue and organ development, remodeling, regeneration, and physiological function. Whereas a significant number of homotypic cell-cell adhesion molecules have been identified, much more is known about those concentrated in epithelia than in endothelia. Among the endothelial cell-cell adhesion molecules, very little is known that is specific to endothelium in the pulmonary and bronchial circulations. This review focuses primarily on homotypic cell-cell adhesion molecules that are or are likely to be important in lung endothelium.

Deletion of JAM-A causes morphological defects in the corneal epithelium

Junctional adhesion molecule-A (JAM-A, JAM-1, F11R) is an Ig domain containing transmembrane protein that has been proposed to function in diverse processes including platelet activation and adhesion, leukocyte transmigration, angiogenesis, epithelial cell shape and endothelial cell migration although its function in vivo is less well established. In the mouse eye, JAM-A protein expression is first detected at 12.5 dpc in the blood vessels of the tunica vasculosa, while it is first detected in both the corneal epithelium and lens between 13.5 and 14.5 dpc. In the corneal epithelium, JAM-A levels remain appreciable throughout life, while JAM-A immunostaining becomes stronger in the lens as the animals age. Both the cornea and lens of mice lacking an intact JAM-A gene are transparent until at least a year of age, although the cells of the JAM-A null corneal epithelium are irregularly shaped. In wild-type mice, JAM-A protein is found at the leading edge of repairing corneal epithelial wounds, however, corneal epithelial wound repair was qualitatively normal in JAM-A null animals. In summary, JAM-A is expressed in the corneal epithelium where it appears to regulate cell shape.

Genomic structure, alternative maturation and tissue expression of the human BBOX1 gene

Gamma-butyrobetaine hydroxylase (BBOX1) is the enzyme responsible for the biosynthesis of l-carnitine, a key molecule of fatty acid metabolism. This cytosolic dimeric protein belongs to the dioxygenase family. In human, enzyme activity has been detected in kidney, liver and brain. The human gene encoding gamma-butyrobetaine hydroxylase is located on chromosome 11. Although the protein structure and activity have been extensively described, little information is available concerning BBOX1 structure and expression. In this study, the organization of the human gene was determined. The structure and functions of the 5'- and 3'-untranslated regions of the human BBOX1 mRNA were characterized in kidney, liver and brain. Our experiments revealed that the transcription initiation of the human BBOX1 gene might occur at 3 different exons, and that the expression level of each type of transcript is organ-specific. We showed that the use of 3 different promoters is responsible for the 5'-end heterogeneity. Investigations on BBOX1 mRNA maturation highlighted an alternative polyadenylation mechanism that generates two 3'-untranslated regions differing by their length. This alternative polyadenylation exhibited a tissue specificity.