WHAT pages
February 2006
As suggested by many researchers at the Lubeck Conference, at the end of December 2005 we sent a question to the Members of the Committees of PCL8 Conference, containing the simple following question: "What is the future of transglutaminases?". We asked also to forward the same question to a couple of researchers whose opinion could be important to this topic. Despite the joke concerning the acronim of this web site, the question was aimed to discuss about the recent findings and the research perspective about transglutaminases.
We have received some replies. The first message was by Kaphil Mehta (Texas, U.S.A.), and it is reported below:
Dear Francesco: I appreciate your efforts in initiating the forum for open discussion on the future of transglutaminases. I hope several investigators will be able to participate and share their thoughts on this important topic. This will help not only the senior investigators but also the new comers in the field to address important issues in a hope to use TGases as target for treating certain diseases. From various presentations at the recent PLC8 meeting in Leubeck, it was evident that transglutaminases play a role in normal and pathologic conditions either by cross link certain proteins or by virtue of their ability to function as signaling molecules. Among others, TG2 continues to be the most diverse and mysterious member of the TGase family. It can catalyze multiple reactions (transamidation, GTPase, PDI, kinase) and also serve as a signaling molecule. Its expression in response to certain stresses can lead to apoptotic death of the cells. However, its expression in chemo/radiation-resistant and metastatic cancer cells suggests some functions contrary to this. Indeed, our recent work (Oncogene, 2006, In press) suggest that down regulation of TG2 can render cancer cells sensitive to apoptosis. Indeed, some recent literature also suggests that TG2 can protect certain cell types from apoptosis. This aspect of TG2 may be critical in understanding the biology of cancer cells that are hard to treat. It is imperative to understand and zero on the factors that make this protein to act a survival factor. In this context, I would like to know if anyone has attempted to delineate the proteins that interact with TG2 using Y2H or similar system. We have identified at least 4 important signaling molecules that closely associate with TG2 in cancer cells. Similar information on other proteins that interact with TG2 should help understand its ability to serve in different configurations.
Another reply has been sent by Carlo Bergamini (Ferrara, Italy):
Dear Francesco, I think you have actually asked two questions, "WHAT" as a site and "what" directions are we really moving to. 1) About the site: I think you made a nice and useful service of information. If it is possible it would be fine to reinforce it further, including a bioinformatics forum dedicated to transglutaminase and eventually opening a forum for access to international grants, since at least in Italy, money is being cut continuously short. I do not know the situation oversea but a more aggregate participation to EEC calls should be organized, acting both at the planning level (I mean before calls are actually published) and at the real application time. WHAT could also be the forum for raising interest from factories. 2) About the scientific topics, several issues should possibly be further explored: My interest is obviously on structure (which is my research field) but several interesting points are emerging. To mention the hottest one, in my opinion the involvement of the enzyme in human pathology is the most promising. I am very curious about the role of endothelial transglutaminase in acute and chronic inflammatory diseases, along with the promising issues related to neurodegenerative pathologies. Further biotecnologic applications should be explored, although this is more relevant for grants than for basic science. I really think little is emerging in this perspective. Another point which has not yet been fully explored is represented by the "new" side-activities of type 2 transglutaminase (PDI and now protein kinase activities) whose regulation and functional evaluation is still at the very beginning. With the hope these few lines might be useful to everybody. Regards Carlo Bergamini
We hope that many other experts in TGases may find the time to send us their opinion about the future of this class of enzymes: we will be glad to guest all the additional replies.
January 2005
Thanks to Rolf Hilgenfeld and Carlo Bergamini, we know that very soon
all the information regarding the 8th International Conference on
Protein Crosslinking and Transglutaminases in Lubeck, Germany, will be
available. In the mean time, many information are already available at
the following web sites:
http://pcl8.biochem.uni-luebeck.de/
http://www.biochem.uni-luebeck.de/
April 2004
We received by e-mail a request of information about the next transglutaminase conference. We have no information about it, at the present, and we will be happy to put here any news the WHATers wish to spread around.
Here you find three links to article devoted to the memory of Peter:
In Memory of Peter SteinertJuly 2003
We received several questions about the next International Conference on Transglutaminases, which should be held on 2004.
Therefore, we decided to put here any more message with information about it. The following messages represent the first round of replies we received.
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15 July 2003 Hi Francesco I am not sure I have a lot of information.As you are aware Richard Eckert was going to try to organise it in the States.Failing this which may be likely ESF funds were going to be a possible source of monies to hold it in Europe 2004 or 2005 Regards Martin --------- Dear Friends, as the organizer of the last International Conference on Transglutaminases and Protein Crosslinking, I really know what an enormous effort and how long a time is required for a successful meeting. Because I am really convinced that these regular meetings are focal points in our scientific activity, I imagine that the time is ripe to choose a new location and a definite time schedule for the next one. I hope that the efforts Richard Eckert is making will be fruitful or that, alternatively, those among us who are more deeply engaged in this programme will rapidly take contacts with each other to make the necessary steps. With best regards and my warmest wishes to you all Carlo Bergamini --------- Dear Whaters, Francesco Facchiano asked me to write about the status of the organization of the next "8th Internationa Conference on Transglutaminases and protein crosslinkings reactions" that should be held in 2004. To my knowledge, the organization of the next Conference is still not decided yet. However, during the last ESF-PCL Steering Committee meeting, that took place last May in Debrecen (Hungary) during the "Protein Cross-linking in Neural Inclusisons:Transglutaminases in neurodegeneration" workshop, it has been proposed that the next International Conference sponsored by ESF-PBL programme should be held in Germany in 2004. Anyhow, the final decision concerning the Organizers location and timing should be announced after the next ESF-PBL Steering Committee meeting in Strasbourg (15-16 November 2003). Of course, the Whaters will be informed immediately. Let me take this opportunity to wish to all of you very good holydays. Sincerely. Mauro Piacentini
November 2001
Report on the Workshop on "Transglutaminases, Protein Cross-Linking and Coeliac Disease"
Dr. Carlo Bergamini was so kind to write for us a short Report from the Tampere Workshop on "Transglutaminases, Protein Cross-Linking and Coeliac Disease", just to inform the WHATers which were not able to attend such Conference about the News in the Transglutaminase field.April 2001
Two papers showing the effects of Transglutaminase gene disruption have been recently published on two different top journals. At the present time these papers are extremely interesting for reaserchers on transglutaminase fields. If you want to say anything about, and discuss with the Transglutaminase's People, please do not hesitate to put your comments about such papers on W.H.A.T.
Targeted inactivation of Gh/transglutaminase II.
Nanda N, Iismaa SE, Owens WA, Husain A, Mackay F, Graham RM.
J Biol Chem 2001 Mar 26.
Click here for the Medline abstract.
Gene Disruption of Tissue Transglutaminase
Vincenzo De Laurenzi and Gerry Melino
Mol Cell Biol 2001 Jan;21(1):148-55.
Click here for the Medline abstract.
February 2001
Dear colleagues,
you can find enclosed all the information concerning the 7th International Congress on Amino Acids and Proteins. As usual, a session of the meeting is dedicated to polyamines. This year, for the first time, a part of this session is focused on the posttranslational modification of protein by polyamines catalyzed by transglutaminases. I hope you may find the time to attend the meeting, giving us the opportunity of enjoying your precious contributions.
Please, visit the meeting internet site enclosed for more informations.
Looking forward to meeting you in Vienna next August.
Simone Beninati, Ph.D.
Organizer and Chairman of the Polyamine Session
Polyamine Session - Call for papers
January 2001
A recent article, entitled Gene Disruption of Tissue Transglutaminase, has been published on Molecular and Cellular Biology, January 2001, p. 148-155, Vol. 21, No. 1.
Click here to see the article at the journal site.
We invite our users to read it and discuss it with the WHAT community.
Talking point no. 5
Thu Sep 30, 1999
Dear Laurie,
Thank you for your talking point. It is a clear and upgraded source of information on the transglutaminases. In fact, now this enzyme is becoming an interesting player in vascular biology too, after years of presence in coagulation, neurologic and dermatologic fields. Transglutaminase type 2 is currently considered possibly involved in a number of important diseases, as well as in apoptosis and cell differentiation, and this justifies the efforts of transglutaminase-people to identify its cellular function(s), at the present time not yet elucidated. Therefore your question is very interesting and, as you write, very intricate, if we take in consideration also that transglutaminase seems to be an important G-protein inside the nucleus. And, finally, what about the ATPase function reported by several researchers, or the GTP-hydrolyzing activity which could be related to a modulation of the intracellular GTP levels?
I am sure that your talking point will trigger an increasing number of questions, and, hopefully, some answer in the next future.
Francesco Facchiano
Talking point no. 4
Fri, 3 September 1999
Tissue transglutaminase received another push into the field of cell Biology when, thanks to Bob Graham, Mi-Jae Im and several other workers and their colleagues, we learned three years ago that it not only binds nucleotides and undergoes allosteric inhibition in their presence, but can also act as the
a subunit of a heterodimeric G-protein complex (Gh) in a reconstituted signal pathway. The protein, whose alter ego had gone undiscovered for years prior to sequence analysis, signals to PLC-d1 when coupled to a1B or 1D adrenoreceptors in cardiac myocytes. These receptors apparently use both Gq/11 and Gh pathways to similar ends, but differences may exist in the qualitative nature and duration of the signal and the means of receptor-uncoupling and inactivation. Specifically, in conditions of local sustained calcium transients, the signal pathway is interrupted by receptor dissociation, the isopeptide cross-linking active site becoming simultaneously accessible.
With a publication from Garrett Fitzgerald’s group for months ago (J Biol Chem, 274, (18) 12774-12779, 1999) we discovered that type-2 Tg/Gh
a had unknowingly been masquerading for some years in the freezer of yet another vascular physiologist, this time as signal partner to the TP (thromboxane receptor) of platelets and vascular smooth muscle cells. Although we have promising leads on the mode of association of Gha to PLC-d1, we know next to nothing about how it associates with its receptors - the lack of similarity between intracellular loop domains of a1 adrenoreceptors and TP is unhelpful in this regard. More importantly, we don’t have the convincing proof we hope for, that Gha serves a major signal function in the context of pathways coupled to several key receptors. The cross-linking reactions of type 2 Tg/Gha have become synonymous with programmed death. If the protein really can act as a functional switch at the cytosolic level in living tissues, between signalling in viable cells and death, then we would witness a new form of developmental regulation (proposed by us in Gill et al., Brain Res 788, 95-103, 1998).
Probing this intricate switch may be harder than it seems. Several groups set out a couple of years ago to generate the necessary in vivo data, using tissue-specfic promoters to get localized over-expression, thus stimulating the Gh-related signal pathway - methodology standardised for the heterotrimeric G-proteins. Steve Liggett’s studies with cardiac overexpression published a few weeks ago (J Biol Chem, 21291-21296, 1999) and confirmed by other unpublished work, illustrated the problems inherent within this approach. The phenotype was predominated by changes to heart interstitial tissues. As for many studies performed in vitro, Liggett and colleagues found predictably that most of the protein overexpressed in the heart found its way to the high-calcium environment of the cell surface where transglutamination occurred by default, leading to the fibrosis which is characteristic of connective tissue cross-linking reactions - a complication not expected for a G-protein with a single function.
Perhaps these initial experiments, resulting as they did in a very high level of overexpression, may have obscured intracellular functions of the protein. But this is unlikely, and new approaches which should follow, involving some careful dissection of the Tg active site and regions of the protein needed for nucleotide and calcium-binding,
(Monsonego et al., J. Biol. Chem. 272, 3724-3732, 1997) will generate a clearer picture. The existence of natural splice variants with different nucleotide-binding capabilities in neural tissue suggest the regulation of the two-function signal system of tissue transglutaminase can happen at more than one level, and several imaginative new approaches will be needed to resolve this interesting problem.
Watch this space!
Talking point no.3
Fri, 26 Mar 1999
Dear all,
It may be that our work on prostate TGase, which is going to be published in Archives of Biochemistry and Biophysics, would be of interest to you. A seminar on this matter was already given by myself at the Università del Molise in Campobasso, Italy. You can find therefore the title, the authors, and the abstract of this paper.
Looking forward to receiving your comments,
Sincerely yours
Raffaele Ragone
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Overlapping between fluorescence modifications and activation of prostate transglutaminase induced by sodium dodecyl sulfate
*
Carla ESPOSITO, Ciro ESPOSITO, Ivana CAPUTO, Patrizia COLICCHIO, Raffaele PORTA(1) and Raffaele RAGONE
Dipartimento di Biochimica e Biofisica "F. Cedrangolo", Seconda Università di Napoli, via Costantinopoli 16, 80138 Naples, Italy and (1)Centro Interdipartimentale di Ricerca sui Peptidi Bioattivi, Università di Napoli "Federico II", via Mezzocannone 4, 80134 Naples, Italy
ABSTRACT
The transglutaminase from rat coagulating gland secretion has been proposed as a new member of the transglutaminase family. Its basal activity is about 11-fold lower than other transglutaminases (for example, the cytosolic tissue transglutaminase), but reaches levels comparable to those of other transglutaminases on addition of specific surfactant agents. There is no study devoted to understanding the molecular basis of this apparently anomalous activation, which is maximal at ~1.5 mM sodium dodecyl sulfate. We provide evidence that in the presence of this detergent modifications of the intrinsic fluorescence as well as energy transfer of the protein fluorescence to a micellar probe parallel the activation of the enzyme. As the SDS concentration inducing maximal activation equals the critical micellar concentration, the biological activity of this transglutaminase appears to be modulated by the binding of micellar aggregates. In fact, the enzyme is modified by post-translational modifications consisting of some lipid tails. At least two of these tails could act as aggregation nuclei of the enzyme with detergents. This behavior is different from that typical of molecular forms purified from other sources.
Talking point no. 2
Dear Francesco,
I'm writing this email to congratulate with you for the excellent work that you are doing with the
transglutaminase site. To me, the site is allowing all the transglutaminase scientist to have a
"home" were to meet and to discuss about transglutaminases. To this regard, this my email is to
invite all the european scientists working on transglutaminases interested in joining the European
Science Foundation proposal, to get in touch with prof Hilgenfeld or dr. Weiss in Jena or with
any rapporteur of the proposal. For more details, please visit the site
www.imb-jena.de/www_sbx/esf/esf.html
Looking forward hearing from new interested participants, many thanks.
Yours Sincerely,
Vittorio Gentile
Talking point no. 1
What about the specificity of transglutamination? In other words, how many different proteins inside or outside the cell can be modified by transglutaminase(s)? This is, in my opinion, one of the most asked questions in cell biology or protein chemistry meetings when somebody starts to talk about this enzyme.
Therefore I think this question might be a good argument to start our meditations around transglutaminase. Several researchers have investigated in the past this question, but a widespread and currently updating talking point around this topic seems to be very interesting.
Some considerations about the specificity are:
- by definition an enzyme is able to specifically catalyze a chemical modification of substrates; the enzyme is also able to specifically bind some cofactors (calcium, GTP in the case of transglutaminase), but the latter is also a specific substrate for the GTP-hydrolyzing action;
- a number of proteins has been published as transglutaminase substrates; among them there are other enzymes, growth hormones and proteins constituent of cytoskeleton, i.e. both weakly and highly expressed proteins inside the cell. On the other hand, several proteins have been reported as devoid of any transglutaminase substrate activity.
- among the substrates of transglutaminase(s) there are the stronger and the weaker ones, accordingly to the measured Km for the substrate. In most cases the Km has been measured in vitro: what happens in vivo? Most probably the strongest substrates play a role in physiological conditions too, whereas the others may become a good substrate under certain conditions (e.g. elevated intracellular calcium concentrations).
What about the specificity of a substrate for the different isoforms of transglutaminase?
What is the opinion of other people working in transglutaminase field?
Francesco Facchiano, MD
Laboratory of Vascular Pathology
IDI, Rome, Italy