Localization of the human prostate transglutaminase (type IV) gene (TGM4) to chromosome 3p21.33-p22 by fluorescence in situ hybridization

The association between genetic variations and morphology-based brain networks changes in Alzheimer's disease

Alzheimer's disease (AD) is a highly heritable disease. The morphological changes of cortical cortex (such as, cortical thickness and surface area) in AD always accompany by the change of the functional connectivity to other brain regions and influence the short- and long-range brain network connections, causing functional deficits of AD. In this study, the first hypothesis is that genetic variations might affect morphology-based brain networks, leading to functional deficits; the second hypothesis is that protein-protein interaction (PPI) between the candidate proteins and known interacting proteins to AD might exist and influence AD. 600 470 variants and structural magnetic resonance imaging scans from 175 AD patients and 214 healthy controls were obtained from the Alzheimer's Disease Neuroimaging Initiative-1 database. A co-sparse reduced-rank regression model was fit to study the relationship between non-synonymous mutations and morphology-based brain networks. After that, PPIs between selected genes and BACE1, an enzyme that was known to be related to AD, are explored by using molecular dynamics (MD) simulation and co-immunoprecipitation (Co-IP) experiments. Eight genes affecting morphology-based brain networks were identified. The results of MD simulation showed that the PPI between TGM4 and BACE1 was the strongest among them and its interaction was verified by Co-IP. Hence, gene variations influence morphology-based brain networks in AD, leading to functional deficits. This finding, validated by MD simulation and Co-IP, suggests that the effect is robust.

Prostate transglutaminase (TGase-4, TGaseP) enhances the adhesion of prostate cancer cells to extracellular matrix, the potential role of TGase-core domain

Background

Transglutaminase-4 (TGase-4), also known as the Prostate Transglutaminase, is an enzyme found to be expressed predominately in the prostate gland. The protein has been recently reported to influence the migration and invasiveness of prostate cancer cells. The present study aimed to investigate the influence of TGase-4 on cell-matrix adhesion and search for the candidate active domain[s] within the protein.

Methods

Human prostate cancer cell lines and prostate tissues were used. Plasmids that encoded different domains and full length of TGase-4 were constructed and used to generate sublines that expressed different domains. The impact of TGase-4 on in vitro cell-matrix adhesion, cell migration, growth and in vivo growth were investigated. Interactions between TGase-4 and focal adhesion complex proteins were investigated using immunoprecipitation, immunofluorescence and phosphospecific antibodies.

Results

TGase-4 markedly increased cell-matrix adhesion and cellular migration, and resulted in a rapid growth of prostate tumours in vivo. This effect resided in the Core-domain of the TGase-4 protein. TGase-4 was found to co-precipitate and co-localise with focal adhesion kinase (FAK) and paxillin, in cells, human prostate tissues and tumour xenografts. FAK small inhibitor was able to block the action mediated by TGase-4 and TGase-4 core domain.

Conclusion

TGase-4 is an important regulator of cell-matrix adhesion of prostate cancer cells. This effect is predominately mediated by its core domain and requires the participation of focal adhesion complex proteins.

Genetic disruption of the copulatory plug in mice leads to severely reduced fertility

Seminal fluid proteins affect fertility at multiple stages in reproduction. In many species, a male's ejaculate coagulates to form a copulatory plug. Although taxonomically widespread, the molecular details of plug formation remain poorly understood, limiting our ability to manipulate the structure and understand its role in reproduction. Here I show that male mice knockouts for transglutaminase IV (Tgm4) fail to form a copulatory plug, demonstrating that this gene is necessary for plug formation and lending a powerful new genetic tool to begin characterizing plug function. Tgm4 knockout males show normal sperm count, sperm motility, and reproductive morphology. However, very little of their ejaculate migrates into the female's reproductive tract, suggesting the plug prevents ejaculate leakage. Poor ejaculate migration leads to a reduction in the proportion of oocytes fertilized. However, Tgm4 knockout males fertilized between 3-11 oocytes, which should be adequate for a normal litter. Nevertheless, females mated to Tgm4 knockout males for approximately 14 days were significantly less likely to give birth to a litter compared to females mated to wild-type males. Therefore, it appears that the plug also affects post-fertilization events such as implantation and/or gestation. This study shows that a gene influencing the viscosity of seminal fluid has a major influence on male fertility.

Characterization of the transglutaminase gene family in zebrafish and in vivo analysis of transglutaminase-dependent bone mineralization

We have characterized the protein cross-linking enzyme transglutaminase (TGs) genes in zebrafish, Danio rerio, based on the analysis of their genomic organization and phylogenetics. Thirteen zebrafish TG genes (zTGs) have been identified, of which 11 show high homology to only 3 mammalian enzymes: TG1, TG2 and FXIIIa. No zebrafish homologues were identified for mammalian TGs 3-7. Real-time PCR analysis demonstrated distinct temporal expression profiles for zTGs in larvae and adult fish. Analysis by in situ hybridization revealed restricted expression of zTG2b and zFXIIIa in skeletal elements, resembling expression of their mammalian homologues in osteo-chondrogenic cells. Mammalian TG2 and FXIIIa have been implicated in promoting osteoblast differentiation and bone mineralization in vitro, however, mouse models lacking either gene have no skeletal phenotype likely due to a compensation effect. We show in this study that mineralization of the newly formed vertebrae is significantly reduced in fish grown for 5 days in the presence of TG inhibitor KCC-009 added at 3-5 days post fertilization. This treatment reduces average vertebrae mineralization by 30%, with complete inhibition in some fish, and no effect on the overall growth and vertebrae number. This is the first in vivo demonstration of the crucial requirement for the TG-catalyzed cross-linking activity in bone mineralization.

Prostate transglutaminase: a unique transglutaminase and its role in prostate cancer

Prostate transglutaminase-4, also known as TGM4 or transglutaminase P, belongs to the prostate transglutaminase protein family, but is almost uniquely distributed in the prostate gland. Recent years have seen an expansion of interest in this enzyme, which is intriguingly expressed in prostate tissues and prostate cancer. In recent studies, the molecule has been found to have a diverse impact on prostate cancer cell growth, migration and invasiveness, and to be involved in the tumor–endothelial interaction and epithelial–mesenchymal transition, and has a wide interaction with other molecular complexes implicating it as a possible biomarker of aggressive versus nonaggressive cancer, as well as a therapeutic factor. This article reviews the recent progress and discusses the controversies and future directions in this exciting area of prostate cancer research.

Prostate transglutaminase (TGase-4) antagonizes the anti-tumour action of MDA-7/IL-24 in prostate cancer

Background

Transglutamiase-4 (TGase-4), also known as prostate transglutaminase, belongs to the TGase family and is uniquely expressed in the prostate gland. The functions of this interesting protein are not clearly defined. In the present study, we have investigated an unexpected link between TGase-4 and the melanoma differentiation-associated gene-7/interleukin-24 (MDA-7/IL-24), a cytokine known to regulate the growth and apoptosis of certain cancer and immune cells.

Methods

Frozen sections of normal and malignant human prostate tissues and human prostate cancer (PCa) cell lines PC-3 and CA-HPV-10, cell lines expressing low and high levels of TGase-4, and recombinant MDA-7/IL-24 (rhMDA-7/IL-24) were used. Expression construct for human TGase-4 was generated using a mammalian expression vector with full length human TGase-4 isolated from normal human prostate tissues. PC-3 cells were transfected with expression construct or control plasmid. Stably transfected cells for control transfection and TGase-4 over expression were created. Similarly, expression of TGase-4 in CA-HPV-10 cells were knocked down by way of ribozyme transgenes. Single and double immunofluorescence microscopy was used for localization and co-localization of TGase-4 and MDA-7/IL-24 in PCa tissues and cells with antibodies to TGase-4; MDA-7/IL-24; IL-20alpha; IL-20beta and IL-22R. Cell-matrix adhesion, attachment and migration were by electric cell substrate impedance sensing and growth by in vitro cell growth assay. A panel of small molecule inhibitors, including Akt, was used to determine signal pathways involving TGase-4 and MDA-7/IL-24.

Results

We initially noted that MDA-7 resulted in inhibition of cell adhesion, growth and migration of human PCa PC-3 cells which did not express TGase-4. However, after the cells over-expressed TGase-4 by way of transfection, the TGase-4 expressing cells lost their adhesion, growth and migratory inhibitory response to MDA-7. On the other hand, CA-HPV-10 cells, a cell type naturally expressing high levels of TGase-4, had a contrasting response to MDA-7 when compared with PC-3 cells. Inhibitor to Akt reversed the inhibitory effect of MDA-7, only in PC-3 control cells, but not the TGase-4 expressing PC-3 cells. In human prostate tissues, TGase-4 was found to have a good degree of co-localization with one of the MDA-7 receptor complexes, IL-20Ra.

Conclusion

The presence of TGase-4 has a biological impact on a prostate cancer cell's response to MDA-7. TGase-4, via mechanism(s) yet to be identified, blocked the action of MDA-7 in prostate cancer cells. This has an important implication when considering the use of MDA-7 as a potential anticancer cytokine in prostate cancer therapies.

Possible role of the transglutaminases in the pathogenesis of Alzheimer's disease and other neurodegenerative diseases

Transglutaminases are ubiquitous enzymes which catalyze posttranslational modifications of proteins. Recently, transglutaminase-catalyzed post-translational modification of proteins has been shown to be involved in the molecular mechanisms responsible for human diseases. Transglutaminase activity has been hypothesized to be involved also in the pathogenetic mechanisms responsible for several human neurodegenerative diseases. Alzheimer's disease and other neurodegenerative diseases, such as Parkinson's disease, supranuclear palsy, Huntington's disease, and other polyglutamine diseases, are characterized in part by aberrant cerebral transglutaminase activity and by increased cross-linked proteins in affected brains. This paper focuses on the possible molecular mechanisms by which transglutaminase activity could be involved in the pathogenesis of Alzheimer's disease and other neurodegenerative diseases, and on the possible therapeutic effects of selective transglutaminase inhibitors for the cure of patients with diseases characterized by aberrant transglutaminase activity.

Physio-pathological roles of transglutaminase-catalyzed reactions

Transglutaminases (TGs) are a large family of related and ubiquitous enzymes that catalyze post-translational modifications of proteins. The main activity of these enzymes is the cross-linking of a glutaminyl residue of a protein/peptide substrate to a lysyl residue of a protein/peptide co-substrate. In addition to lysyl residues, other second nucleophilic co-substrates may include monoamines or polyamines (to form mono- or bi-substituted /crosslinked adducts) or -OH groups (to form ester linkages). In the absence of co-substrates, the nucleophile may be water, resulting in the net deamidation of the glutaminyl residue. The TG enzymes are also capable of catalyzing other reactions important for cell viability. The distribution and the physiological roles of TG enzymes have been widely studied in numerous cell types and tissues and their roles in several diseases have begun to be identified. “Tissue” TG (TG2), a member of the TG family of enzymes, has definitely been shown to be involved in the molecular mechanisms responsible for a very widespread human pathology: i.e. celiac disease (CD). TG activity has also been hypothesized to be directly involved in the pathogenetic mechanisms responsible for several other human diseases, including neurodegenerative diseases, which are often associated with CD. Neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, supranuclear palsy, Huntington’s disease and other recently identified polyglutamine diseases, are characterized, in part, by aberrant cerebral TG activity and by increased cross-linked proteins in affected brains. In this review, we discuss the physio-pathological role of TG-catalyzed reactions, with particular interest in the molecular mechanisms that could involve these enzymes in the physio-pathological processes responsible for human neurodegenerative diseases.

The prostate transglutaminase (TGase-4, TGaseP) regulates the interaction of prostate cancer and vascular endothelial cells, a potential role for the ROCK pathway

Prostate transglutaminase (TGase-4 or TGaseP) is an enzyme that is uniquely expressed in prostate tissues. The function of the TGase, implicated in the cell-matrix, is yet to be fully established. In the present study, we investigated the role of TGase-4 in tumor-endothelial cell interactions, by creating a panel of prostate cancer cell lines that have different expression profiles of human TGase-4. Here, we report that prostate cancer cells PC-3, when over-expressing TGase-4 (PC-3(TGase4exp)) increased their ability to adhere to quiescent and activated (by hepatocyte growth factor) endothelial cells. In contrast, the prostate cancer cell CAHPV-10, which expressed high levels of TGase-4, reduced the adhesiveness to the endothelial cells after TGase-4 expression was knocked down. By using frequency based electric cell impedance sensing, we found that TGase-4 mediated adhesion resulted in a change in impedance at low frequency (400 Hz), indicating a paracellular pathway disruption. The study further showed that expression of TGase-4 rendered the cells to exert regulation of endothelial interaction by bypassing the ROCK pathway. It is therefore concluded, that TGase-4 plays a pivotal role in the interaction between endothelial cells and prostate cancer cells, an action which is independent of the ROCK pathway.

Plasticity and stabilization of neuromuscular and CNS synapses: interactions between thrombin protease signaling pathways and tissue transglutaminase

The first association of the synapse as a potential site of neurodegenerative disease burden was suggested for Alzheimer's disease (AD) almost 30 years ago. Since then protease:protease inhibitor (P:PI) systems were first linked to functional regulation of synaptogenesis and synapse withdrawal at the neuromuscular junction (NMJ) more than 20 years ago. Confirmatory evidence for the involvement of the synapse, the rate-limiting or key unit in neural function, in AD did not become clear until the beginning of the 1990s. However, over the past 15 years evidence for participation of thrombin, related serine proteases and neural PIs, homologous and even identical to those of the plasma clot cascade, has been mounting. Throughout development a balance between stabilization forces, on the one hand, and breakdown influences, on the other, becomes established at synaptic junctions, just as it does in plasma clot proteins. The formation of protease-resistant cross-links by the transglutaminase (TGase) family of enzymes may add to the stability for this balance. The TGase family includes coagulation factor XIIIA and 8 other different genes, some of which may also influence the persistence of neural connections. Synaptic location of protease-activated, G-protein-coupled receptors (PARs) for thrombin and related proteases, their serpin and Kunitz-type PIs such as protease nexin I (PNI), alpha1-antichymotrypsin (alpha-ACT), and the Kunitz protease inhibitor (KPI)-containing secreted forms of beta-amyloid protein precursor (beta-APP), along with the TGases and their putative substrates, have all been amply documented. These findings strongly add to the conclusion that these molecules participate in the eventual structural stability of synaptic connections, as they do in coagulation cascades, and focus trophic activity on surviving terminals during periods of selective contact elimination. In disease states, this imbalance is likely to be shifted in favor of destabilizing forces: increased and/or altered protease activity, enhanced PAR influence, decreased and/or altered protease inhibitor function, reduction and/or alteration in tTG expression and activity, and alteration in its substrate profile. This imbalance further initiates a cascade of events leading to inappropriate programmed cell death and may well be considered evidence of synaptic apoptosis.

Evolution of transglutaminase genes: identification of a transglutaminase gene cluster on human chromosome 15q15. Structure of the gene encoding transglutaminase X and a novel gene family member, transglutaminase Z

We isolated and characterized the gene encoding human transglutaminase (TG)(X) (TGM5) and mapped it to the 15q15.2 region of chromosome 15 by fluorescence in situ hybridization. The gene consists of 13 exons separated by 12 introns and spans about 35 kilobases. Further sequence analysis and mapping showed that this locus contained three transglutaminase genes arranged in tandem: EPB42 (band 4.2 protein), TGM5, and a novel gene (TGM7). A full-length cDNA for the novel transglutaminase (TG(Z)) was obtained by anchored polymerase chain reaction. The deduced amino acid sequence encoded a protein with 710 amino acids and a molecular mass of 80 kDa. Northern blotting showed that the three genes are differentially expressed in human tissues. Band 4.2 protein expression was associated with hematopoiesis, whereas TG(X) and TG(Z) showed widespread expression in different tissues. Interestingly, the chromosomal segment containing the human TGM5, TGM7, and EPB42 genes and the segment containing the genes encoding TG(C),TG(E), and another novel gene (TGM6) on chromosome 20q11 are in mouse all found on distal chromosome 2 as determined by radiation hybrid mapping. This finding suggests that in evolution these six genes arose from local duplication of a single gene and subsequent redistribution to two distinct chromosomes in the human genome.

Loss of tissue transglutaminase as a biomarker for prostate adenocarcinoma

BACKGROUND

Additional molecular tissue biomarkers for prostate carcinoma are needed to stratify patients with clinically suspicious findings, such as an elevated prostate specific antigen (PSA) with a negative biopsy, according to risk.

METHODS

Prostate tissues from 43 cancer cases and 47 controls with no evidence of cancer were labeled for transglutaminase by immunohistochemistry. Immunoreactivity was quantified using the Autocyte Pathology Workstation. In addition, quantitative fluorescence image analysis was used to compare transglutaminase concentrations in cells obtained by fine-needle aspiration from excised prostates. Loss of gene expression was evaluated by reverse transcriptase-polymerase chain reaction and growth with 5-azacytidine.

RESULTS

Visually, benign glands from controls generally expressed tissue transglutaminase, whereas regions with adenocarcinoma generally were negative. With quantitative immunohistochemistry, 41 of 43 adenocarcinoma of the prostate (CaP) cases expressed lower mean percentage areas positive for transglutaminase than did 30 of 30 benign prostatic hyperplasia (BPH) and 17 of 17 prostatitis cases (P < 0.0001; odds ratio [OR], 1577; 95% confidence interval (CI), 74-33, 820; relative risk [RR], 25; 95% CI, 6-95). Quantitative immunofluorescence of 3277 cells collected by FNA from 19 CaP cases and 645 cells from 5 cases of BPH showed that the mean content of transglutaminase was 93 femtograms (fg) for the CaP-derived cells and 138 fg for the BPH cells (P < 0.0001). Receiver operating curve analysis of the immunohistochemistry data showed an optimized threshold produced 95% sensitivity with 100% specificity. Growth of LNCaP cells with 5-azacytidine failed to stimulate transglutaminase expression, suggesting that loss of expression was likely not attributable to promoter methylation.

CONCLUSIONS

Measurements of transglutaminase on tissue sections provides additional diagnostic information that is potentially useful for risk assessment of patients with suspicious clinical findings, such as nodules or positive PSA and negative biopsies, without overdetecting disease.

Tissue transglutaminase: an enzyme with a split personality

Tissue transglutaminase (tTG) belongs to the family of transglutaminase enzymes that catalyze the posttranslational modification of proteins via Ca(2+)-dependent cross-linking reactions. The catalytic action of tTG results in the formation of an isopeptide bond that is of great physiological significance since it is highly resistant to proteolysis and denaturants. Although tTG-mediated cross-linking reactions have been implicated to play a role in diverse biological processes, the precise physiological function of the enzyme remains unclear. Recent data, however, suggest that the protein polymers resulting from tTG-catalyzed reactions may play a role in commitment of cells to undergo apoptosis. On the same token, tTG-mediated formation of insoluble protein aggregates may underlie the markers of numerous pathological conditions, such as the senile plaques in Alzheimer's disease and the Lewy bodies in Parkinson's disease. In addition to catalyzing Ca(2+)-dependent cross-linking reactions, tTG can also bind and hydrolyze guanosine triphosphate and adenosine triphosphate. By virtue of this ability, tTG has been identified as a novel G-protein that interacts and activates phospholipase C following stimulation of the alpha-adrenergic receptor. The ability of tTG to mediate signal transduction may contribute to its involvement in the regulation of cell cycle progression. The following review summarizes the important features of this multifunctional enzyme that have emerged as a result of recent work from different laboratories.

Organization and chromosomal mapping of mouse Gh/tissue transglutaminase gene (Tgm2)

The mouse Gh/tissue transglutaminase gene (Tgm2), coding a dual-function protein that both binds guanosine triphosphate (GTP) and catalyzes the posttranslational modification of proteins by transamidation of glutamine residues, has been cloned. Sequence analysis of Tgm2 and comparison with the TGase sequences of other species allowed correction of several apparent sequencing artifacts in the Tgm2 cDNA. Tgm2 spans approximately 34 kb and has 13 exons and 12 introns. Although the structure of Tgm2 shows similarity to that of other transglutaminase genes, with introns ranging from 921 bp to >5 kb, several introns differ considerably in size from those of the human Gh gene, TGM2. Tgm2 maps to the distal region of mouse chromosome 2, a region syntenic to human chromosome 20q containing TGM2. Tgm2 is in the vicinity of two uncloned mouse mutations, diminutive (dm) and blind-sterile (bs). Genomic DNA from dm mice was unavailable; however, Southern blot analysis of bs DNA showed no gross rearrangements of Tgm2.

The human prostate-specific transglutaminase gene (TGM4): genomic organization, tissue-specific expression, and promoter characterization

Human prostate-specific transglutaminase (hTGP) is a cross-linking enzyme secreted by the prostate. In this study, we performed dot blot analysis of 50 normal human tissues to demonstrate unambiguously the prostate-specific expression of hTGP. Furthermore, we elucidated the genomic organization of the TGM4 gene, the gene encoding hTGP. The structure of this gene displays striking similarity to that of other transglutaminase (TGase) genes. The TGM4 gene spans approximately 35 kb of genomic DNA and consists of 13 exons and 12 introns. The main transcription initiation site is located 52 bp upstream of the translational start codon. A hTGP splice variant of intron 1 was detected. This splice variant contains an in-frame antisense Alu element insertion. The TGM4 promoter was analyzed by sequencing and transfection experiments. At positions -1276 to -563, the promoter harbors a cyclophilin pseudogene with 94% similarity to the cyclophilin A cDNA. Deletion mapping of the TGM4 promoter in the transiently transfected human prostate cancer cell line PC346C showed comparable activity of 2.1-, 1.5-, and 0.5-kb promoter fragments.

Loss of heterozygosity for defined regions on chromosomes 3, 11 and 17 in carcinomas of the uterine cervix

Loss of heterozygosity (LOH) frequently occurs in squamous cell carcinomas of the uterine cervix and indicates the probable sites of tumour-suppressor genes that play a role in the development of this tumour. To define the localization of these tumour-suppressor genes, we studied loss of heterozygosity in 64 invasive cervical carcinomas (stage IB and IIA) using the polymerase chain reaction with 24 primers for polymorphic repeats of known chromosomal localization. Chromosomes 3, 11, 13, 16 and 17, in particular, were studied. LOH was frequently found on chromosome 11, in particular at 11q22 (46%) and 11q23.3 (43%). LOH on chromosome 11p was not frequent. On chromosome 17p13.3, a marker (D17S513) distal to p53 showed 38% LOH, whereas p53 itself showed only 20% LOH. On the short arm of chromosome 3, LOH was frequently found (41%) at 3p21.1. The beta-catenin gene is located in this chromosomal region. Therefore, expression of beta-catenin protein was studied in 39 cases using immunohistochemistry. Staining of beta-catenin at the plasma membrane of tumour cells was present in 38 cases and completely absent in only one case. The tumour-suppressor gene on chromosome 3p21.1 may be beta-catenin in this one case, but (an)other tumour-suppressor gene(s) must also be present in this region. For the other chromosomes studied, 13q (BRCA-2) and 16q (E-cadherin), only sporadic losses (< 15% of cases) were found. Expression of E-cadherin was found in all of 37 cases but in six cases the staining was very weak. No correlation was found between clinical and histological parameters and losses on chromosome 3p, 11q and 17p. In addition to LOH, microsatellite instability was found in one tumour for almost all loci and in eight tumours for one to three loci. In conclusion, we have identified three loci with frequent LOH, which may harbour new tumour-suppressor genes, and found microsatellite instability in 14% of cervical carcinomas.

Tissue specific and androgen-regulated expression of human prostate-specific transglutaminase

Transglutaminases (TGases) are calcium-dependent enzymes catalysing the post-translational cross-linking of proteins. In the prostate at least two TGases are present, the ubiquitously expressed tissue-type TGase (TGC), and a prostate-restricted TGase (TGP). This paper deals with the molecular cloning and characterization of the cDNA encoding the human prostate TGase (hTGP). For this purpose we have screened a human prostate cDNA library with a probe from the active-site region of TGC. The largest isolated cDNA contained an open reading frame encoding a protein of 684 amino acids with a predicted molecular mass of 77 kDa as confirmed by in vitro transcription-translation and subsequent SDS/PAGE. The hTGP gene was tissue-specifically expressed in the prostate, yielding an mRNA of approx. 3.5 kb. Furthermore, a 3-fold androgen-induced upregulation of hTGP mRNA expression has been demonstrated in the recently developed human prostate cancer cell line, PC346C. Other well established human prostate cancer cell lines, LNCaP and PC-3, showed no detectable hTGP mRNA expression on a Northern bolt. The gene coding for prostate TGase was assigned to chromosome 3.