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Guérin Martine


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tél : 02.38.25.78.59 - fax : 02.38.25.55.83

Publications

2015   Références trouvées : 1

Le Meur, R., Culard, F., Nadan, V., Goffinont, S., Coste, F., Guerin, M., Loth, K., Landon, C. and Castaing, B.  (2015)

The nucleoid-associated protein HU enhances 8-oxoguanine base excision by the formamidopyrimidine-DNA glycosylase

Biochemical Journal (2015) 471 (1) 13-23 - doi : 10.1042/BJ20150387
The nucleoid-associated protein HU is involved in numerous DNA transactions and thus is essential in DNA maintenance and bacterial survival. The high affinity of HU for SSBs (single-strand breaks) has suggested its involvement in DNA protection, repair and recombination. SSB-containing DNA are major intermediates transiently generated by bifunctional DNA N-glycosylases that initiate the BER (base excision repair) pathway. Enzyme kinetics and DNA-binding experiments demonstrate that HU enhances the 8-oxoguanine-DNA glycosylase activity of Fpg (formamidopyrimidine-DNA glycosylase) by facilitating the release of the enzyme from its final DNA product (one nucleoside gap). We propose that the displacement of Fpg from its end-DNA product by HU is an active mechanism in which HU recognizes the product when it is still bound by Fpg. Through DNA binding, the two proteins interplay to form a transient ternary complex Fpg/DNA/HU which results in the release of Fpg and the molecular entrapment of SSBs by HU. These results support the involvement of HU in BER in vivo.

The nucleoid-associated protein HU is involved in numerous DNA transactions and thus is essential in DNA maintenance and bacterial survival. The high affinity of HU for SSBs (single-strand breaks) has suggested its involvement in DNA protection, repair and recombination. SSB-containing DNA are major intermediates transiently generated by bifunctional DNA N-glycosylases that initiate the BER (base excision repair) pathway. Enzyme kinetics and DNA-binding experiments demonstrate that HU enhances the 8-oxoguanine-DNA glycosylase activity of Fpg (formamidopyrimidine-DNA glycosylase) by facilitating the release of the enzyme from its final DNA product (one nucleoside gap). We propose that the displacement of Fpg from its end-DNA product by HU is an active mechanism in which HU recognizes the product when it is still bound by Fpg. Through DNA binding, the two proteins interplay to form a transient ternary complex Fpg/DNA/HU which results in the release of Fpg and the molecular entrapment of SSBs by HU. These results support the involvement of HU in BER in vivo.


2014   Références trouvées : 1

Biela, A., Coste, F., Culard, F., Guerin, M., Goffinont, S. Gasteiger, K., Cieśla, J., Winczura, A., Kazimierczuk, Z., Gasparutto, D., Carell, T., Tudek, B., Castaing, B.  (2014)

Zinc finger oxidation of Fpg/Nei DNA glycosylases by 2-thioxanthine : biochemical and X-ray structural characterization

Nucleic Acids Research (2014) 42(16) 10748-10761 - doi : 10.1093/nar/gku613
DNA glycosylases from the Fpg/Nei structural superfamily are base excision repair enzymes involved in the removal of a wide variety of mutagen and potentially lethal oxidized purines and pyrimidines. Although involved in genome stability, the recent discovery of synthetic lethal relationships between DNA glycosylases and other pathways highlights the potential of DNA glycosylase inhibitors for future medicinal chemistry development in cancer therapy. By combining biochemical and structural approaches, the physical target of 2-thioxanthine (2TX), an uncompetitive inhibitor of Fpg, was identified. 2TX interacts with the zinc finger (ZnF) DNA binding domain of the enzyme. This explains why the zincless hNEIL1 enzyme is resistant to 2TX. Crystal structures of the enzyme bound to DNA in the presence of 2TX demonstrate that the inhibitor chemically reacts with cysteine thiolates of ZnF and induces the loss of zinc. The molecular mechanism by which 2TX inhibits Fpg may be generalized to all prokaryote and eukaryote ZnF-containing Fpg/Nei-DNA glycosylases. Cell experiments show that 2TX can operate in cellulo on the human Fpg/Nei DNA glycosylases. The atomic elucidation of the determinants for the interaction of 2TX to Fpg provides the foundation for the future design and synthesis of new inhibitors with high efficiency and selectivity.

DNA glycosylases from the Fpg/Nei structural superfamily are base excision repair enzymes involved in the removal of a wide variety of mutagen and potentially lethal oxidized purines and pyrimidines. Although involved in genome stability, the recent discovery of synthetic lethal relationships between DNA glycosylases and other pathways highlights the potential of DNA glycosylase inhibitors for future medicinal chemistry development in cancer therapy. By combining biochemical and structural approaches, the physical target of 2-thioxanthine (2TX), an uncompetitive inhibitor of Fpg, was identified. 2TX interacts with the zinc finger (ZnF) DNA binding domain of the enzyme. This explains why the zincless hNEIL1 enzyme is resistant to 2TX. Crystal structures of the enzyme bound to DNA in the presence of 2TX demonstrate that the inhibitor chemically reacts with cysteine thiolates of ZnF and induces the loss of zinc. The molecular mechanism by which 2TX inhibits Fpg may be generalized to all prokaryote and eukaryote ZnF-containing Fpg/Nei-DNA glycosylases. Cell experiments show that 2TX can operate in cellulo on the human Fpg/Nei DNA glycosylases. The atomic elucidation of the determinants for the interaction of 2TX to Fpg provides the foundation for the future design and synthesis of new inhibitors with high efficiency and selectivity.


2010   Références trouvées : 2

Picard M. Morisset S., Cloix J. F., Bizot J. C., Guerin M., Beneteau V., Guillaumet G. and Hevor T. K.  (2010)

Pharmacological, neurochemical, and behavioral profile of JB-788, a new 5-HT1A agonist

Neuroscience 169 (3) 1337-1346 - doi : 10.1016/j.neuroscience.2010.05.040
A novel pyridine derivative, 8-4-[(6-methoxy-2,3-dihydro-[1,4]dioxino[2,3-b]pyridine-3-ylmethyl)-amino]-butyl -8-aza-spiro[4.5]decane-7,9-dione hydrochloride, termed JB-788, was designed to selectively target 5-HT(1A) receptors. In the present study, the pharmacological profile of JB-788 was characterized in vitro using radioligands binding tests and in vivo using neurochemical and behavioural experiments. JB-788 bound tightly to human 5-HT(1A) receptor expressed in human embryonic kidney 293 (HEK-293) cells with a K(i) value of 0.8 nM. Its binding affinity is in the same range as that observed for the (+/-)8-OH-DPAT, a reference 5HT(1A) agonist compound. Notably, JB-788 only bound weakly to 5-HT(1B) or 5-HT(2A) receptors and moreover the drug displayed only weak or indetectable binding to muscarinic, alpha(2), beta(1) and beta(2) adrenergic receptors, or dopaminergic D(1) receptors. JB-788 was found to display substantial binding affinity for dopaminergic D(2) receptors and, to a lesser extend to alpha(1) adrenoreceptors. JB-788 dose-dependently decreased forskolin-induced cAMP accumulation in HEK cells expressing human 5-HT(1A), thus acting as a potent 5-HT(1A) receptor agonist (E(max.) 75%, EC(50) 3.5 nM). JB-788 did not exhibit any D(2) receptor agonism but progressively inhibited the effects of quinpirole, a D(2) receptor agonist, in the cAMP accumulation test with a K(i) value of 250 nM. JB-788 induced a weak change in cAMP levels in mouse brain but, like some antipsychotics, transiently increased glycogen contents in various brain regions. Behavioral effects were investigated in mice using the elevated plus-maze. JB-788 was found to increase the time duration spent by animals in anxiogenic situations. Locomotor hyperactivity induced by methamphetamine in mouse, a model of antipsychotic activity, was dose-dependently inhibited by JB-788. Altogether, these results suggest that JB-788 displays pharmacological properties, which could be of interest in the area of anxiolytic and antipsychotic drugs.

A novel pyridine derivative, 8-4-[(6-methoxy-2,3-dihydro-[1,4]dioxino[2,3-b]pyridine-3-ylmethyl)-amino]-butyl -8-aza-spiro[4.5]decane-7,9-dione hydrochloride, termed JB-788, was designed to selectively target 5-HT(1A) receptors. In the present study, the pharmacological profile of JB-788 was characterized in vitro using radioligands binding tests and in vivo using neurochemical and behavioural experiments. JB-788 bound tightly to human 5-HT(1A) receptor expressed in human embryonic kidney 293 (HEK-293) cells with a K(i) value of 0.8 nM. Its binding affinity is in the same range as that observed for the (+/-)8-OH-DPAT, a reference 5HT(1A) agonist compound. Notably, JB-788 only bound weakly to 5-HT(1B) or 5-HT(2A) receptors and moreover the drug displayed only weak or indetectable binding to muscarinic, alpha(2), beta(1) and beta(2) adrenergic receptors, or dopaminergic D(1) receptors. JB-788 was found to display substantial binding affinity for dopaminergic D(2) receptors and, to a lesser extend to alpha(1) adrenoreceptors. JB-788 dose-dependently decreased forskolin-induced cAMP accumulation in HEK cells expressing human 5-HT(1A), thus acting as a potent 5-HT(1A) receptor agonist (E(max.) 75%, EC(50) 3.5 nM). JB-788 did not exhibit any D(2) receptor agonism but progressively inhibited the effects of quinpirole, a D(2) receptor agonist, in the cAMP accumulation test with a K(i) value of 250 nM. JB-788 induced a weak change in cAMP levels in mouse brain but, like some antipsychotics, transiently increased glycogen contents in various brain regions. Behavioral effects were investigated in mice using the elevated plus-maze. JB-788 was found to increase the time duration spent by animals in anxiogenic situations. Locomotor hyperactivity induced by methamphetamine in mouse, a model of antipsychotic activity, was dose-dependently inhibited by JB-788. Altogether, these results suggest that JB-788 displays pharmacological properties, which could be of interest in the area of anxiolytic and antipsychotic drugs.

Fisichella, M., Dabboue, H., Bhattacharyya, S., Lelong, G., Warmont, F., Midoux, P., Pichon, C., Guérin, M., Hevor, T. and Salvetat, J.-P.  (2010)

Uptake of Functionalized Mesoporous Silica Nanoparticles by Human Cancer Cells.

J. Nanosci. Nanotechnol. 10 (4) : 2314-2324


2009   Références trouvées : 1

Fisichella, M., Dabboue, H., Bhattacharyya, S., Saboungi, M.-L., Salvetat J.-P., Hevor, T. and Guérin, M.  (2009)

Mesoporous silica nanoparticles enhance MTT formazan exocytosis in Hela cells and astrocytes

Toxicology in Vitro 23(4), 697-703


2007   Références trouvées : 1

PICARD, M., V. BENETEAU, J. BLUM., GUÉRIN, M., CLOIX, J.F., DUFOUR, T., GUILLAUMET, G. and HEVOR, T.K.  (2007)

Behavioural and neurochemical changes in mice submitted to a new pyridine derivative

Biog. Amines 21, 5-14


2006   Références trouvées : 1

Picard, M., Guérin, M., Cloix, J.F., Dufour, T. and Hevor, T.K.  (2006)

Methionine sulfoximine induces a decrease in the tryptophan level of mouse brain

Biog. Amines (2006) 20 (5-6), 185-192
Methionine sulfoximine is well known as a powerful convulsant in many animals. However the actual mechanism of its epileptogenic property is not known. The aim of the present work is to look for a possible effect of methionine sulfoximine on the level of tryptophan because indolamine system was involved in some models of epilepsy. For this Swiss mice were given different doses of methionine sulfoximine and tryptophan concentration was measured using HPLC. During the preconvulsive period no significant change was observed in tryptophan concentration when 100mg/kg of methionine sulfoximine was administered to the animals. Conversely, during the convulsive period, a significant decrease in tryptophan concentration was observed in different regions of the brain including cerebral cortex, striatum, thalamus and cerebellum. During this convulsive period, "grand mal" type seizures were observed. When the animals recovered, no difference was observed in tryptophan concentration between controls and mice submitted to methionine sulfoximine during the post-convulsive period. When different doses of the convulsant were administered the decrease in tryptophan level was significant with 50, 150 and 200mg/kg during the convulsive period, as compared to controls. The present investigation clearly shows a large decrease of about 50% in tryptophan level of mouse brain during the convulsions induced by methionine sulfoximine. Since positron emission tomography reveals also a disturbance in tryptophan utilization in epileptic man, it is possible that tryptophan could be involved in seizure genesis.

Methionine sulfoximine is well known as a powerful convulsant in many animals. However the actual mechanism of its epileptogenic property is not known. The aim of the present work is to look for a possible effect of methionine sulfoximine on the level of tryptophan because indolamine system was involved in some models of epilepsy. For this Swiss mice were given different doses of methionine sulfoximine and tryptophan concentration was measured using HPLC. During the preconvulsive period no significant change was observed in tryptophan concentration when 100mg/kg of methionine sulfoximine was administered to the animals. Conversely, during the convulsive period, a significant decrease in tryptophan concentration was observed in different regions of the brain including cerebral cortex, striatum, thalamus and cerebellum. During this convulsive period, "grand mal" type seizures were observed. When the animals recovered, no difference was observed in tryptophan concentration between controls and mice submitted to methionine sulfoximine during the post-convulsive period. When different doses of the convulsant were administered the decrease in tryptophan level was significant with 50, 150 and 200mg/kg during the convulsive period, as compared to controls. The present investigation clearly shows a large decrease of about 50% in tryptophan level of mouse brain during the convulsions induced by methionine sulfoximine. Since positron emission tomography reveals also a disturbance in tryptophan utilization in epileptic man, it is possible that tryptophan could be involved in seizure genesis.


1999   Références trouvées : 1

Toulme, F ; Guerin, M ; Robichon, N ; Leng, M ; Rahmouni, AR  (1999)

In vivo evidence for back and forth oscillations of the transcription elongation complex

Embo Journal 18 (18) 5052-5060
We have used a combination of DNA and RNA footprinting experiments to analyze the structural rearrangements experienced by a transcription elongation complex that was halted in vivo by a protein readblock, We show that the complex readblocked within an (ATC/TAG)(n), sequence is in a dynamic equilibrium between upstream- and downstream-translocated conformers. By increasing the strength of the putative RNA-DNA hybrid, the ternary complex is readily trapped in the downstream-translocated conformation, where the melted DNA region is limited to 8 bp, The shift of the equilibrium towards the downstream location is also achieved by introducing within the 5' end of the message an RNA sequence that can pair with a segment of the transcript in the vicinity of the halted ternary complex. Our results demonstrate that within certain template DNA sequences, the back and forth oscillations of the ternary complex actually occur in a multipolymerase system and inside the cell. Furthermore, the cis-acting effect of the upstream RNA sequence underscores an important phenomenon in gene regulation where a transcript may regulate its own elongation.

We have used a combination of DNA and RNA footprinting experiments to analyze the structural rearrangements experienced by a transcription elongation complex that was halted in vivo by a protein readblock, We show that the complex readblocked within an (ATC/TAG)(n), sequence is in a dynamic equilibrium between upstream- and downstream-translocated conformers. By increasing the strength of the putative RNA-DNA hybrid, the ternary complex is readily trapped in the downstream-translocated conformation, where the melted DNA region is limited to 8 bp, The shift of the equilibrium towards the downstream location is also achieved by introducing within the 5’ end of the message an RNA sequence that can pair with a segment of the transcript in the vicinity of the halted ternary complex. Our results demonstrate that within certain template DNA sequences, the back and forth oscillations of the ternary complex actually occur in a multipolymerase system and inside the cell. Furthermore, the cis-acting effect of the upstream RNA sequence underscores an important phenomenon in gene regulation where a transcript may regulate its own elongation.


1998   Références trouvées : 2

Figueroa-Bossi, N ; Guerin, M ; Rahmouni, R ; Leng, M ; Bossi, L  (1998)

The supercoiling sensitivity of a bacterial tRNA promoter parallels its responsiveness to stringent control

Embo Journal 17 (8) 2359-2367
In Salmonella typhimurium, expression of the hisR locus, a tRNA operon, decreases upon inhibiting DNA gyrase. Here, the hisR promoter dependence on negative DNA supercoiling was examined in vivo and in vitro. Mutant analysis showed the sequence determinants of this dependence to lie in the region between the -10 box and the transcription start site. As with most promoters subject to stringent control, this portion of the hisR promoter is C-G-rich, Replacing a C/G bp with T/A at position -7 partially relieves the supercoiling response while changing the sequence between -5 and +1 (-CCCCCG-) for -GTTAA- abolishes the response in vitro and in vivo. The relief of the supercoiling dependence closely correlates with increased promoter susceptibility to melting in vivo and a lesser requirement for initiating nucleotides in the formation of stable initiation complexes in vitro. Studies in isoleucine-starved cells showed that such sequence changes mitigate and abolish the hisR promoter response to stringent control, respectively. The data presented suggest that the hisR promoter's sensitivity to stringent regulation arises from the same physical property that confers supercoiling sensitivity, i.e. resistance to melting. We propose that the stringent control mechanism acts by hampering the ability of RNA polymerase to melt the DNA helix.

In Salmonella typhimurium, expression of the hisR locus, a tRNA operon, decreases upon inhibiting DNA gyrase. Here, the hisR promoter dependence on negative DNA supercoiling was examined in vivo and in vitro. Mutant analysis showed the sequence determinants of this dependence to lie in the region between the -10 box and the transcription start site. As with most promoters subject to stringent control, this portion of the hisR promoter is C-G-rich, Replacing a C/G bp with T/A at position -7 partially relieves the supercoiling response while changing the sequence between -5 and +1 (-CCCCCG-) for -GTTAA- abolishes the response in vitro and in vivo. The relief of the supercoiling dependence closely correlates with increased promoter susceptibility to melting in vivo and a lesser requirement for initiating nucleotides in the formation of stable initiation complexes in vitro. Studies in isoleucine-starved cells showed that such sequence changes mitigate and abolish the hisR promoter response to stringent control, respectively. The data presented suggest that the hisR promoter’s sensitivity to stringent regulation arises from the same physical property that confers supercoiling sensitivity, i.e. resistance to melting. We propose that the stringent control mechanism acts by hampering the ability of RNA polymerase to melt the DNA helix.

Guerin, M ; Robichon, N ; Geiselmann, J ; Rahmouni, AR  (1998)

A simple polypyrimidine repeat acts as an artificial Rho-dependent terminator in vivo and in vitro

Nucleic Acids Research 26 (21) 4895-4900
In this paper, we present evidence that an efficient Rho-dependent terminator can be created by introducing a simple (AG/TC)(n) DNA repeat into a transcription unit, The Rho termination activity in vivo and in vitro is dependent on the length and the orientation of the insert. The transcription of at least 30 bp of the (AG/TC)(n) repeat in the orientation encoding the (rUrC)(n) sequence on the transcript leads to Rho-dependent termination at a downstream non-terminator site, Our results indicate that the high efficiency of this artificial Rho-dependent terminator is due to optimal interactions between the (rUrC), RNA sequence and Rho protein, Thus, our findings strongly suggest that an adequate loading site is the primary determinant for Rho termination activity and provide a more defined system for future investigations.

In this paper, we present evidence that an efficient Rho-dependent terminator can be created by introducing a simple (AG/TC)(n) DNA repeat into a transcription unit, The Rho termination activity in vivo and in vitro is dependent on the length and the orientation of the insert. The transcription of at least 30 bp of the (AG/TC)(n) repeat in the orientation encoding the (rUrC)(n) sequence on the transcript leads to Rho-dependent termination at a downstream non-terminator site, Our results indicate that the high efficiency of this artificial Rho-dependent terminator is due to optimal interactions between the (rUrC), RNA sequence and Rho protein, Thus, our findings strongly suggest that an adequate loading site is the primary determinant for Rho termination activity and provide a more defined system for future investigations.


1997   Références trouvées : 1

Boudvillain, M ; Guerin, M ; Dalbies, R ; SaisonBehmoaras, T ; Leng, M  (1997)

Transplatin-modified oligo(2’-O-methyl ribonucleotide)s : A new tool for selective modulation of gene expression

Biochemistry 36 (10) 2925-2931
In the reaction between trans-diamminedichloroplatinum(II) and single-stranded oligo(2'-O-methyl ribonucleotide)s containing the sequence GNG (N being a nucleotide residue), the 1,3-trans-(Pt (NH3)(2)[GNG]} cross-links are formed. The 1,3-intrastrand cross-links are inert within the single-stranded oligonucleotides. By contrast, they rearrange into interstrand cross-links when the platinated oligonucleotides are paired with their complementary RNA strands. The rate of the interstrand cross-linking reaction depends upon the sequence facing the intrastrand cross-links.

In the reaction between trans-diamminedichloroplatinum(II) and single-stranded oligo(2’-O-methyl ribonucleotide)s containing the sequence GNG (N being a nucleotide residue), the 1,3-trans-(Pt (NH3)(2)[GNG]} cross-links are formed. The 1,3-intrastrand cross-links are inert within the single-stranded oligonucleotides. By contrast, they rearrange into interstrand cross-links when the platinated oligonucleotides are paired with their complementary RNA strands. The rate of the interstrand cross-linking reaction depends upon the sequence facing the intrastrand cross-links.


1996   Références trouvées : 1

Guerin, M ; Leng, M ; Rahmouni, AR  (1996)

High resolution mapping of E-coli transcription elongation complex in situ reveals protein interactions with the non-transcribed strand

Embo Journal 15 (19) 5397-5407
We have used chemical probes and UV light to perform a high resolution mapping of an Escherichia coli transcription elongation complex that was arrested in vivo by a protein readblock at a position distal to the promoter. The in situ probing data provide a precise picture of a constrained ternary complex in which the front edge of the polymerase is located at

We have used chemical probes and UV light to perform a high resolution mapping of an Escherichia coli transcription elongation complex that was arrested in vivo by a protein readblock at a position distal to the promoter. The in situ probing data provide a precise picture of a constrained ternary complex in which the front edge of the polymerase is located at


1995   Références trouvées : 1

Gillet G., Guerin M., Trembleau A., Brun G.  (1995)

A Bcl-2-related gene is activated in avian cells transformed by the Rous sarcoma virus

EMBO Journal (1995) 4 (7) 1372-1381


1994   Références trouvées : 1

Prost S., Lê M. G., Douc-Rasy S., Ahomadegbe J. C., Spielmann M., Guérin M., Riou G.  (1994)

Association of c-erbB2-gene amplification with poor prognosis in non-inflammatory breast carcinomas but not in carcinomas of the inflammatory type

International Journal of Cancer (1994) 58 (6) 763-738


1993   Références trouvées : 1

Gillet G., Michel D., Crisanti P., Guérin M., Herault Y., Pessac B., Calothy G., Brun G., Volovitch M.  (1993)

Serum factors and v-src control two complementary mitogenic pathways in quail neuroretinal cells in culture

Oncogene (1993) 8 (3) 565-574


1990   Références trouvées : 1

Guérin M., Sheng Z. M., Andrieu N., Riou G.  (1990)

Strong association between c-myb and oestrogen-receptor expression in human breast cancer

Oncogene (1990) 5 (1) 131-135


1989   Références trouvées : 1

Guérin M., Gabillot M., Mathieu M .C., Travagli J. P., Spielmann M., Andrieu N., Riou G.  (1989)

Structure and expression of c-erbB-2 and EGF receptor genes in inflammatory and non-inflammatory breast cancer : prognostic significance

International Journal of Cancer (1989) 43 (2) 201-208


1988   Références trouvées : 3

Guérin M., Barrois M., Terrier M. J., Spielmann M., Riou G.  (1988)

Overexpression of either c-myc or c-erbB-2/neu proto-oncogenes in human breast carcinomas : correlation with poor prognosis

Oncogene Research (1988) 3 (1) 21-31

Guerin M., Barrois M., Riou G.  (1988)

The expression of c-myb is strongly associated with the presence of estrogen and progesterone receptors in breast cancer

C R Acad Sci III. (1988) 307 (20) 855-861

Sheng Z. M., Guerin M., Gabillot M., Spielmann M., Riou G.  (1988)

c-Ha-ras-1 polymorphism in human breast carcinomas : evidence for a normal distribution of alleles

Oncogene Research (1988) 2 (3) 245-50


Mots-clés

Maître de conférences , Réparation de l’ADN : structure, fonction et dynamique