Cloning of the human tissue inhibitor of metalloproteinase-4 gene (TIMP4) and localization of the TIMP4 and Timp4 genes to human chromosome 3p25 and mouse chromosome 6, respectively

Contribution of gene polymorphisms on 3p25 to salivary gland carcinoma, ameloblastoma, and odontogenic keratocyst in the Chinese Han population

OBJECTIVE

This study aimed to investigate the contribution of gene polymorphisms in 3p25 to salivary gland carcinoma (SGC), ameloblastoma (AM), and odontogenic keratocyst (OKC) in the Chinese Han population.

STUDY DESIGN

Sixteen tag-single nucleotide polymorphisms (SNPs) within 5 genes (SYN2, TIMP4, PPARG, RAF1, and IQSEC1) in 3p25 were genotyped in 411 individuals with or without SGC, AM, and OKC. Genotype, clinical phenotype, and bioinformatics analyses were performed to evaluate the function of candidate SNPs.

RESULTS

SYN2-rs3773364, TIMP4-rs3755724, PPARG-rs10865710, and PPARG-rs1175544 were related to decreased SGC susceptibility, whereas IQSEC1-rs2600322 and IQSEC1-rs2686742 decreased and increased AM risk, respectively. Stratification analysis revealed that the significance of the identified SNPs was stronger in females or individuals younger than 46 years in SGC. PPARG-rs10865710 and PPARG-rs1175544 were associated with lower lymph node metastasis. SYN2-rs3773364 and PPARG-rs1175544 were associated with favorable SGC patient survival. Functional assessments linked PPARG-rs1175544 to PPARG expression regulation. Linkage disequilibrium analysis revealed a haplotype (SYN2-rs3773364-A, TIMP4-rs3817004-A, and TIMP4-rs3755724-C) associated with decreased susceptibility to SGC. Generalized multifactor dimensionality reduction analysis indicated the gene-gene interactions among IQSEC1, TIMP4, and PPARG in SGC, AM, and OKC progression.

CONCLUSIONS

These variants play important roles in the progression of SGC, AM, and OKC in the Chinese Han population and may be considered biomarkers for early diagnosis and prognosis prediction.

Metalloproteinases and their roles in human cancer

It is now widely appreciated that members of the matrix metalloproteinase (MMP) family of enzymes play a key role in cancer development and progression along with many of the hallmarks associated with them. The activity of these enzymes has been directly implicated in extracellular matrix remodeling, the processing of growth factors and receptors, the modulation of cell migration, proliferation, and invasion, the epithelial to mesenchymal transition, the regulation of immune responses, and the control of angiogenesis. Certain MMP family members have been validated as biomarkers of a variety of human cancers including those of the breast, brain, pancreas, prostate, ovary, and others. The related metalloproteinases, the A disintegrin and metalloproteinases (ADAMs), share a number of these functions as well. Here, we explore these essential metalloproteinases and some of their disease-associated activities in detail as well as some of their complementary translational potential. Anat Rec, 2019. © 2019 Wiley Periodicals, Inc.

Contribution of TIMP4 rs3755724 polymorphism to susceptibility to focal epilepsy in Malaysian Chinese

Neuroinflammation can damage the brain and plays a critical role in the pathophysiology of epilepsy. Tissue inhibitor of metalloproteinase 4 (TIMP4) is an inflammation-induced apoptosis and matrix turnover factor involved in several neuronal disorders and inflammatory diseases. Evidence has shown linkage disequilibrium between rs3755724 (-55C/T) of this gene with synapsin 2 (SYN2) rs3773364 and peroxisome proliferator-activated G receptor (PPARG) rs2920502 loci, which contribute to epilepsy in Caucasians. The aim of this study was to examine the association of these loci alone or their haplotypes with the risk of epilepsy in the Malaysian population. Genomic DNA of 1241 Malaysian Chinese, Indian, and Malay subjects (670 patients with epilepsy and 571 healthy individuals) was genotyped for the candidate loci by using the Sequenom MassArray method. Allele and genotype association of rs3755724 with susceptibility to epilepsy was significant in the Malaysian Chinese with focal epilepsy under codominant and dominant models (C vs. T: 1.5 (1.1-2.0), p=0.02; CT vs. TT: 1.8 (1.2-2.8), p=0.007 and 1.8 (1.2-2.7), p=0.006, respectively). The T allele and the TT genotype were more common in patients than in controls. No significant association was found between rs2920502 and rs3773364-rs3755724-rs2920502 haplotypes for susceptibility to epilepsy in each ethnicity. This study provides evidence that the promoter TIMP4 rs3755724 is a new focal epilepsy susceptibility variant that is plausibly involved in inflammation-induced seizures in Malaysian Chinese.

A blood-based biomarker panel to detect acute stroke

BACKGROUND

The aim of this study was to develop an adjunctive, peripheral biomarker test to differentiate ischemic strokes, intracranial hemorrhages (ICHs), and stroke mimics in the acute setting.

METHODS

Serum samples were collected from 167 patients who presented with an acute neurologic deficit within 24 hours of symptom onset. Patients were adjudicated to ischemic stroke, ICH, and mimic pathology groups based on clinical and radiographic findings. Samples were tested for levels of 262 potential markers. A multivariate Cox proportional hazards regression model of 5 biomarkers was built by stepwise selection and validated by bootstrapping. Its discriminative capacity was quantified by C index and net reclassification improvement (NRI).

RESULTS

The final model consisted of eotaxin, epidermal growth factor receptor, S100A12, metalloproteinase inhibitor-4, and prolactin. It demonstrated a discriminative capacity for ischemic stroke versus mimic (C = .92), ischemic stroke and ICH versus mimic (C = .93), and ischemic stroke versus ICH (C = .82). The inclusion of biomarkers to a model consisting of age, race, and gender resulted in an NRI of 161% when detecting ischemic stroke versus mimic (P < .0001), an improvement of 171% when detecting ischemic strokes plus ICH versus mimic (P < .0001), and an improvement of 56% when detecting ischemic strokes versus ICH (P = .1419).

CONCLUSIONS

These results suggest that information obtained from a 5-biomarker panel may add valuable information in the early evaluation and management of patients with stroke-like symptoms.

Targeting matrix metalloproteinases in heart disease: lessons from endogenous inhibitors

Basic pharmacological/transgenic studies have clearly demonstrated a cause-effect relationship between the induction and activation of matrix metalloproteinases (MMPs) and adverse changes in the structure and function of the left ventricle (LV). Thus, regulation of MMP induction and/or activation would appear to be a potential therapeutic target in the context of cardiovascular disease, such as following myocardial infarction (MI). However, pharmacological approaches to inhibit MMPs have yet to be realized for clinical applications. The endogenous inhibitors of the MMPs (TIMPs) constitute a set of 4 small molecules with unique functionality and specificity. Thus, improved understanding on the function and roles of individual TIMPs may provide important insight into the design and targets for pharmacological applications in LV remodeling processes, such as MI. Therefore, the purpose of this review will be to briefly examine biological functions and relevance of the individual TIMPs in terms of adverse LV remodeling post-MI. Second is to examine the past outcomes and issues surrounding clinical trials targeting MMPs in the post MI context and how new insights into TIMP biology may provide new pharmacological targets. This review will put forward the case that initial pharmacological attempts at MMP inhibition were over-simplistic and that future strategies must recognize the diversity of this matrix proteolytic system and that lessons from TIMP biology may lead to future therapeutic strategies.

Glial cell missing-1 mediates over-expression of tissue inhibitor of metalloproteinase-4 in severe pre-eclamptic placental villi

BACKGROUND

Severe pre-eclampsia (sPE) causes significant maternal morbidity and intrauterine growth restriction as a result of severe placental dysfunction. Defects in the formation of both extra-villous and villous trophoblast are characteristic of this disease. The outer syncytiotrophoblast layer covering the placental villi develops syncytial knots and focal necrosis while reduced invasion of the extra-villous trophoblast results in a reduced maternal blood supply and ischemia of the placental villi. The transcription factor glial cell missing-1 (GCM1) regulates formation of both types of trophoblast. GCM1 expression is reduced in placental villi of women with sPE but the functional downstream consequences of reduced GCM1 expression are unknown.

METHODS AND RESULTS

In floating first trimester villous explants we demonstrated increased mRNA (2.5-fold, n = 12) and protein level (9.8-fold) of tissue inhibitor of metalloproteinase-4 (TIMP4) following repression of GCM1 (70 ± 7%) by small interfering-RNA, using RT-PCR and western blot, respectively. Similar increases in TIMP4 mRNA (4.2-fold, n = 7, P< 0.001 versus control) and protein levels were found following gene silencing of GCM1 in BeWo cells (<90% knock down of protein). TIMP4 protein was increased in placenta from women with sPE (3.5 ± 0.4 pg/µg, n = 8), compared with preterm (1.7 ± 0.17 pg/µg, n = 9) and term controls (1.6 ± 0.16 pg/µg, n = 9; P< 0.01; quantified by enzyme-linked immunosorbent assay and visualized using immunohistochemistry) with reduced GCM1 expression, mostly in the pathologic syncytial knots.

CONCLUSIONS

TIMP4 is a downstream target of GCM1 that may link the consequences of reduced GCM-1-directed trophoblast differentiation to histologic and functional components of disordered placentation in sPE.

Genetic polymorphisms of matrix metalloproteinases and their inhibitors in potentially malignant and malignant lesions of the head and neck

Matrix metalloproteinases (MMPs) are a family of zinc-dependent proteinases that are capable of cleaving all extra cellular matrix (ECM) substrates. Degradation of matrix is a key event in progression, invasion and metastasis of potentially malignant and malignant lesions of the head and neck. It might have an important polymorphic association at the promoter regions of several MMPs such as MMP-1 (-1607 1G/2G), MMP-2 (-1306 C/T), MMP-3 (-1171 5A/6A), MMP-9 (-1562 C/T) and TIMP-2 (-418 G/C or C/C). Tissue inhibitors of metalloproteinases (TIMPs) are naturally occurring inhibitors of MMPs, which inhibit the activity of MMPs and control the breakdown of ECM. Currently, many MMP inhibitors (MMPIs) are under development for treating different malignancies. Useful markers associated with molecular aggressiveness might have a role in prognostication of malignancies and to better recognize patient groups that need more antagonistic treatment options. Furthermore, the introduction of novel prognostic markers may also promote exclusively new treatment possibilities, and there is an obvious need to identify markers that could be used as selection criteria for novel therapies. The objective of this review is to discuss the molecular functions and polymorphic association of MMPs and TIMPs and the possible therapeutic aspects of these proteinases in potentially malignant and malignant head and neck lesions. So far, no promising drug target therapy has been developed for MMPs in the lesions of this region. In conclusion, further research is required for the development of their potential diagnostic and therapeutic possibilities.

Tissue inhibitor of metalloproteinases-4. The road less traveled

Tissue inhibitors of metalloproteinases (TIMPs) regulate diverse processes, including extracellular matrix (ECM) remodeling, and growth factors and their receptors' activities through the inhibition of matrix metalloproteinases (MMPs). Recent evidence has shown that this family of four members (TIMP-1 to TIMP-4) can also control other important processes, such as proliferation and apoptosis, by a mechanism independent of their MMP inhibitory actions. Of these inhibitors, the most recently identified and least studied is TIMP-4. Initially cloned in human and, later, in mouse, TIMP-4 expression is restricted to heart, kidney, pancreas, colon, testes, brain and adipose tissue. This restricted expression suggests specific and different physiological functions. The present review summarizes the information available for this protein and also provides a putative structural model in order to propose potential relevant directions toward solving its function and role in diseases such as cancer.

Association of synapsin 2 with schizophrenia in families of Northern European ancestry

The synapsin 2 (Syn2) gene (3p25) is implicated in synaptogenesis, neurotransmitter release, and the localization of nitric oxide synthase to the proximity of its targets. In this study we investigated linkage and association between the Syn2 locus and schizophrenia. 37 pedigrees of Northern European ancestry from the NIMH Human Genetics Initiative collection were used. Four microsatellites and twenty SNPs were genotyped. Linkage (FASTLINK) and association (TRANSMIT, PDTPHASE) between markers and schizophrenia were evaluated. A maximum heterogeneity LOD of 1.93 was observed at marker D3S3434 with a recessive mode of inheritance. Significant results were obtained for association with schizophrenia using TRANSMIT (minimum nominal p=0.0000005) and PDTPHASE (minimum nominal p=0.014) using single marker analyses. Haplotype analysis using markers in introns 5 and 6 of Syn2 provided a single haplotype that is significantly associated with schizophrenia using TRANSMIT (nominal p<0.00000001) and PDTPHASE (nominal p=0.02). Simulation studies confirm the global significance of these results, but demonstrate that the small p-values generated by the bootstrap routine of TRANSMIT can be consistently anticonservative. Review of the literature suggests that Syn2 is likely to be involved in the etiology or pathogenesis of schizophrenia.

Myocardial Matrix Remodeling and the Matrix Metalloproteinases: Influence on Cardiac Form and Function

It is now becoming apparent that dynamic changes occur within the interstitium that directly contribute to adverse myocardial remodeling following myocardial infarction (MI), with hypertensive heart disease and with intrinsic myocardial disease such as cardiomyopathy. Furthermore, a family of matrix proteases, the matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPs), has been recognized to play an important role in matrix remodeling in these cardiac disease states. The purpose of this review is fivefold: 1) to examine and redefine the myocardial matrix as a critical and dynamic entity with respect to the remodeling process encountered with MI, hypertension, or cardiomyopathic disease; 2) present the remarkable progress that has been made with respect to MMP/TIMP biology and how it relates to myocardial matrix remodeling; 3) to evaluate critical translational/clinical studies that have provided a cause-effect relationship between alterations in MMP/TIMP regulation and myocardial matrix remodeling; 4) to provide a critical review and analysis of current diagnostic, prognostic, and pharmacological approaches that utilized our basic understanding of MMP/TIMPs in the context of cardiac disease; and 5) most importantly, to dispel the historical belief that the myocardial matrix is a passive structure and supplant this belief that the regulation of matrix protease pathways such as the MMPs and TIMPs will likely yield a new avenue of diagnostic and therapeutic strategies for myocardial remodeling and the progression to heart failure.

Tissue inhibitors of metalloproteinases (TIMPs): their biological functions and involvement in oral disease

Several families of enzymes are responsible for the degradation of extracellular matrix (ECM) proteins during the remodeling of tissues. An important family of such enzymes is that of the matrix metalloproteinases (MMPs). To control MMP-mediated ECM breakdown, tissue inhibitors of metalloproteinases (TIMPs) are able to inhibit MMP activity. A disturbed balance of MMPs and TIMPs is found in various pathologic conditions, such as cancer, rheumatoid arthritis, and periodontitis. The role of MMPs in pathology has been extensively described in the literature. The main focus of this review lies in the biological functions of TIMPs and their occurrence in disease, especially in the head and neck area. Their biological functions and their role in diseases like oral cancers and periodontitis, and in the development of cleft palate, will be discussed. Finally, the diagnostic and therapeutical opportunities of TIMPs will be evaluated.

Novel functions of TIMPs in cell signaling

Tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors of matrix metalloproteinases (MMPs) and the balance between MMPs/TIMPs regulates the extracellular matrix (ECM) turnover and remodeling during normal development and pathogenesis. Increasing evidence indicates a much more complex role for TIMPs during tumor progression and angiogenesis, in addition to their regulation of MMP-mediated ECM degradation. In this article, we review both the MMP-dependent and -independent actions of TIMPs for the regulation of cell death, cell proliferation, and angiogenesis, with a particular emphasis on TIMP-1 in the regulation of tetraspanin/integrin-mediated cell survival signal transduction pathways.

Angiogenesis in non-small cell lung cancer. A new target for therapy

Non-small cell lung cancer (NSCLC) is cured with surgery in a minority of affected persons. Chemotherapy and radiation can palliate and extend survival of patients with disease not amenable to surgery. Consequently, new treatment options are urgently needed. In the era of molecularly targeted therapeutics, the recent direction in cancer research has been to identify and modulate specific events in tumorigenesis. Angiogenesis, or new vessel formation, is one such event elucidated to be fundamental to the development, growth, and metastasis of cancers and is one of the characteristics that differentiates tumor from host. Thus, targeting of tumor neovasculature continues to generate tremendous enthusiasm and effort in drug development. Extensive research into the role of angiogenesis in NSCLC has produced a host of novel targets; their potential inhibitors, now numbering over 40, are in various phases of clinical testing around the world. The current lead compounds include inhibitors of matrix metalloproteinases, angiogenic growth factors and their receptor tyrosine kinases. Despite their impressive activity in animal models, definitive evidence of their antitumor activity in humans is yet to be established. We face several challenges as we look to advance the field of antiangiogenesis for the treatment of cancer, namely, the need for a better understanding of the optimal timing and dosing of antiangiogenic agents, the validation of imaging and quantification methods of tumor angiogenesis, and a new clinical trials design for a more expedient evaluation of novel cytostatic target modulators.

Identification, regulation and role of tissue inhibitor of metalloproteinases-4 (TIMP-4) in human platelets

1. Matrix metalloproteinase-2 (MMP-2) released during activation of human platelets by aggregating agents and cancer cells is known to stimulate platelet aggregation. 2. The expression, activity and role of tissue inhibitors of metalloproteinases (TIMPs), natural inhibitors of MMPs, in isolated human platelets were investigated. 3. Western blot, reverse zymography, immunogold electron microscopy, aggregometry (collagen-, thrombin and HT-1080 human fibrosarcoma cells-induced aggregation), flow cytometry and the release of (14)C-serotonin from labelled platelets recruited to the aggregate were used to characterize the presence and function of platelet TIMPs. 4. TIMP-4 (23 kDa) has been identified as the major MMP inhibitor (12-16 ng per 10(8) platelets) in human platelets. Platelets expressed lower (<1 ng per 10(8) platelets) amounts of TIMP-1. No other TIMPs were detected using Western blot analysis. 5. TIMP-4 co-localized with MMP-2 in resting platelets and was released upon platelet aggregation induced by collagen and thrombin. 6. Collagen resulted also in the release of higher molecular weight (60 kDa) complexes of TIMP-4. 7. The release of TIMP-4 was reduced by prostacyclin and S-nitroso-glutathione (GSNO), an NO donor. 8. Human recombinant TIMP-4 (rTIMP-4), but not human rTIMP-1, inhibited partially both platelet aggregation and recruitment. 9. The recombinant TIMP-4 potentiated the recruitment inhibitor effects of GSNO. 10. TIMP-4 was not released during platelet aggregation induced by HT-1080 cells. 11. Human rTIMP-4 exerted a biphasic effect on HT-1080 cells-induced aggregation. 12. Thus, TIMP-4 is the major intraplatelet MMP inhibitor and it is involved in regulation of platelet aggregation and recruitment.

Characterization of the murine Timp4 gene, localization within intron 5 of the synapsin 2 gene and tissue distribution of the mRNA

Tissue inhibitor of matrix metalloproteinases type 4 (TIMP-4), the newest member in the mammalian TIMP family of inhibitors of matrix metalloproteinases (MMPs), differs from the other three TIMPs by its restricted expression pattern. This suggests that TIMP-4 could play a role in tissue-specific regulation of extracellular matrix (ECM) turnover. To define this role, modulation of TIMP-4 production by overexpression, aberrant expression and inactivation of the Timp4 gene in transgenic mice should be performed. In preparation for such experiments we have cloned and characterized the murine Timp4 gene and determined the tissue distribution of its mRNA in mice. The gene spans 7.1 kb, consists of five exons and shares considerable homology with the other Timp genes. The gene is located on mouse chromosome 6 in an antisense orientation between exons 5 and 6 of the mouse synapsin 2 (Syn2) gene. A similar organization is common to all four human/mouse TIMP and SYN genes and to the single synapsin/Timp locus in Drosophila. The highest levels of TIMP-4 mRNA were seen in postnatal mouse heart, ovary and brain. Determination of the spatial expression pattern of TIMP-4 mRNA by in situ hybridization in the heart revealed a diffuse distribution in cardiac muscle cells. In the ovary, cyclic variation was observed in TIMP-4 mRNA levels. In situ hybridization demonstrated the strongest expression of TIMP-4 mRNA in the corpus luteum. The data suggest that TIMP-4 plays a role in the normal physiology of the heart and the ovary, most likely related to maintenance of the delicate balance between MMPs and TIMPs.

Identification of an initiator-like element essential for the expression of the tissue inhibitor of metalloproteinases-4 (Timp-4) gene

We have used real-time quantitative reverse transcriptase PCR (TaqMan) to quantify the expression of the four tissue inhibitor of metalloproteinases (Timp) genes in mouse tissues during development and in the adult. Among the four Timp genes, Timp-4 shows the most restricted pattern of expression, with highest RNA levels in brain, heart and testes. These data indicate that in the brain, Timp-4 transcripts are temporally regulated during development, becoming more abundant than those of the other Timps after birth. Cloning of the Timp-4 gene confirmed a five-exon organization resembling that of Timp-2 and Timp-3, and like all Timps, Timp-4 is located within an intron of a synapsin gene. Ribonuclease protection analysis and 5'-rapid amplification of cDNA ends PCR identified multiple transcription starts for Timp-4 from brain and heart mRNA. The promoter region of Timp-4 was functional in transient transfection analysis in mouse C3H10T1/2 fibroblasts, where it directed basal expression that was non-inducible by serum. The TATA-less promoter contains consensus motifs for Sp1 and an inverted CCAAT box upstream of an initiator-like element that is in close proximity to a transcription start site. Mutation of the CCAAT box caused a 2-fold increase in reporter expression. More significantly, mutation of the Sp1 motif or initiator-like element almost completely abolished reporter expression. This first functional characterization of the Timp-4 promoter shows it to be distinct from other members of the Timp family and provides insights into potential mechanisms controlling the tight spatio-temporal expression pattern of the gene.

mRNA expression of matrix metalloproteases and their inhibitors differs in subtypes of renal cell carcinomas

Altered expression of matrix metalloproteases (MMPs) and their inhibitors, the tissue inhibitors of matrix metalloproteases (TIMPs), has been demonstrated in various tumour tissues. mRNA expression patterns of MMP-1, MMP-2, MMP-3, MMP-9, MMP-11, MMP-12, MMP-14 and TIMP-1, TIMP-2, TIMP-3 and TIMP-4 were evaluated by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in 30 renal cell carcinomas (RCC), as well as in the surrounding tissues. Expression of the MMPs was significantly stronger in the carcinomas than in non-malignant tissues. High levels were demonstrated particularly in clear cell RCCs (CC-RCC). Except for MMP-1, MMP expression in the papillary RCCs (P-RCC) was, for most MMPs, significantly lower. Expression of the TIMPs in malignant cells of both subtypes was weak, with the exception of TIMP-4 which was strongly expressed in the P-RCCs and downregulated in the CC-RCCs. The latter was correlated with chromosomal loss of 3p, harbouring the TIMP-4 gene locus. In conclusion, deregulated expression of the MMPs and TIMPs in RCCs differs according to histology, grade, size and cytogenetic characteristics, suggesting that MMP and TIMP expression patterns play an important role for the typical histomorphological features of RCC subtypes and their respective biological behaviour.

Tissue factor pathway inhibitor-2 is a novel inhibitor of matrix metalloproteinases with implications for atherosclerosis

Degradation of ECM, particularly interstitial collagen, promotes plaque instability, rendering atheroma prone to rupture. Previous studies implicated matrix metalloproteinases (MMPs) in these processes, suggesting that dysregulated MMP activity, probably due to imbalance with endogenous inhibitors, promotes complications of atherosclerosis. We report here that the serine proteinase inhibitor tissue factor pathway inhibitor-2 (TFPI-2) can function as an MMP inhibitor. TFPI-2 diminished the ability of the interstitial collagenases MMP-1 and MMP-13 to degrade triple-helical collagen, the primary load-bearing molecule of the ECM within human atheroma. In addition, TFPI-2 also reduced the activity of the gelatinases MMP-2 and MMP-9. In contrast to the "classical" tissue inhibitors of MMPs (TIMPs), TFPI-2 expression in situ correlated inversely with MMP levels in human atheroma. TFPI-2 colocalized primarily with smooth muscle cells in the normal media as well as the plaque's fibrous cap. Conversely, the macrophage-enriched shoulder region, the prototypical site of matrix degradation and plaque rupture, stained only weakly for TFPI-2 but intensely for gelatinases and interstitial collagenases. Evidently, human mononuclear phagocytes, an abundant source of MMPs within human atheroma, lost their ability to express this inhibitor during differentiation in vitro. These findings establish a new, anti-inflammatory function of TFPI-2 of potential pathophysiological significance for human diseases, including atherosclerosis.

Detailed mapping of a congenital heart disease gene in chromosome 3p25

Distal deletion of chromosome 3p25-pter (3p- syndrome) produces a distinct clinical syndrome characterised by low birth weight, mental retardation, telecanthus, ptosis, and micrognathia. Congenital heart disease (CHD), typically atrioventricular septal defect (AVSD), occurs in about a third of patients. In total, approximately 25 cases of 3p- syndrome have been reported world wide. We previously analysed five cases and showed that (1) the 3p25-pter deletions were variable and (2) the presence of CHD correlated with the proximal extent of the deletion, mapping a CHD gene centromeric to D3S18. To define the molecular pathology of the 3p- syndrome further, we have now proceeded to analyse the deletion region in a total of 10 patients (five with CHD), using a combination of FISH analysis and polymorphic markers, for up to 21 loci from 3p25-p26. These additional investigations further supported the location of an AVSD locus within 3p25 and refined its localisation. Thus, the critical region was reduced to an interval between D3S1263 and D3S3594. Candidate 3p25 CHD genes, such as PMCA2 (ATP2B2), fibulin 2, TIMP4, and Sec13R, were shown to map outside the target interval. Additionally, the critical region for the phenotypic features of the 3p- phenotype was mapped to D3S1317 to D3S17 (19-21 cM). These findings will accelerate the identification of the 3p25 CHD susceptibility locus and facilitate investigations of the role of this locus in non-syndromic AVSDs, which are a common form of familial and isolated CHD.

Physiological roles of matrix metalloproteinases: implications for tumor growth and metastasis

Physiological processes involving remodelling of the extracellular matrix, such as wound healing, embryogenesis, angiogenesis, and the female reproductive cycle, require the activity of matrix metalloproteinases (MMPs). This group of proteases degrades basal membranes and connective tissues and plays an essential role in the homeostasis of the extracellular matrix. An imbalance in the expression or activity of MMPs can have important consequences in diseases such as multiple sclerosis, Alzheimer's disease, or the development of cancers. Because of the pathophysiological importance of MMPs, their activity is highly controlled in order to confine them to specific areas. An activation cascade, initiated by the proteolysis of plasminogen, cleaves proMMPs, and every step is controlled by specific activators or inhibitors. MMPs destabilize the organization of the extracellular matrix and influence the development of cancer by contributing to cell migration, tumor cell proliferation, and angiogenesis. Accordingly, these proteases possess an important role in cell-matrix interactions by affecting fundamental processes such as cell differentiation and proliferation. Therefore, the characterization of MMPs involved in specific types and stages of tumors will significantly improve the diagnosis and treatment of these cancers in humans.Key words: matrix metalloproteinases, physiology, cancer, cell invasion, extracellular matrix.

Invertebrate tissue inhibitor of metalloproteinase: structure and nested gene organization within the synapsin locus is conserved from Drosophila to human

Vertebrate tissue inhibitors of metalloproteinases (TIMPs) regulate extracellular matrix metalloproteinases and are thus involved in a wide variety of developmental and physiological processes. By identifying cDNAs of a transcript detected within an intron of the Drosophila synapsin gene we have cloned the Drosophila TIMP gene (Timp), which represents the first invertebrate member of the TIMP gene family. Sequence analysis revealed an open reading frame of 210 amino acids with 35% identity to human TIMPs and a conserved exon-intron structure. Analysis of sequence data from the Sanger Centre demonstrated that the human TIMP3 gene is encoded within intron V of the human synapsin-III gene, indicating that the nested organization of TIMP and synapsin genes may be a general feature conserved in evolution. We therefore speculate that the human TIMP4 gene will be located in intron V of the human synapsin-II gene on chromosome 3p25, and we present preliminary evidence that a human synapsin-IV gene is located near the TIMP2 gene on chromosome 17q23-q25.

Analysis of coding sequences for tissue inhibitor of metalloproteinases 1 (TIMP1) and 2 (TIMP2) in patients with aneurysms

Aneurysms are characterized by dilation, i.e. expansion and thinning of all the arterial wall layers, which is accompanied by remodeling of the connective tissue. Genes involved in the regulation of tissue remodeling are therefore candidate genes. We analyzed TIMP1 and TIMP2 coding sequences in 12 individuals with abdominal aortic aneurysms (AAA), one individual with AAA and intracranial aneurysms (IA), four individuals with IA and two clinically unaffected individuals. We identified two nucleotide variants in both the TIMP1 and the TIMP2 coding sequences. All differences occurred in the third base positions of codons and were neutral polymorphisms. A significant difference was observed in the frequency of TIMP2 nt 573 polymorphism between 168 alleles from AAA patients and 102 control alleles.