The Allen lab employs molecular, biochemical, cellular, and physiological approaches to study the signalling processes involved in the onset and/or maintenance of cardiomyopathy. Our research interests focus in two main areas: 1) the role of the p38 MAP kinase pathway in cardiac remodelling and 2) the physiological function and molecular pharmacology of GPRCs in the nuclear membranes in cardiac cells.
Activation of p38 results in hypertrophy, fibrosis and heart failure. These results suggest that inhibition of the p38 MAPK pathway may be of use in the treatment of heart disease. Unfortunately, clinical trials using p38 inhibitors have revealed both side effects and use-dependent loss of inhibitory efficacy. Therefore it is important to identify and characterize the downstream targets of p38 in heart and determine if their selective inhibition could prevent, or reverse, detrimental cardiac remodelling while avoiding the side effects associated with direct inhibition of p38. MK2, MK3 and MK5 are protein kinases activated by p38 and expressed in heart.
We have demonstrated endothelin receptors and beta-adrenergic receptors on the nuclear envelope in cardiac myocytes and have more recently shown isoproterenol and angiotensin II stimulate transcription in isolated cardiac nuclei whereas endothelin-1 is inhibitory. In addition, a microarray analysis of mRNA expression has demonstrated that endothelin-1, isoproterenol and angiotensin II have distinct effects upon gene expression in isolated nuclei. We have now developed caged agonists and antagonists that enable us to study of the role of nuclear GPCRs within intact cells. These studies should identify the signalling pathways involved in regulating transcription by the nuclear pool of endothelin receptors. In addition, we will determine both if nuclear endothelin receptors are involved in heart failure.
The ultimate goal of these studies is develop novel therapeutic agents to treat cardiovascular disease.
Bruce G. Allen, Ph.D. (Professor, Dept. of Medicine, Université de Montréal)
Sherine Ali, MD/Ph.D. (Physiology, University of Suez Canal), PhD student (Physiology, Université de Montréal). Tel.: 514-376-3330, Ext.: 3592
Ana Branco, Ph.D. (Bioscience, University of Coimbra), Postdoctoral fellow (Biochemistry, Université de Montréal). Tel.: 514-376-3330, Ext.: 3592
Pramod Sahadevan, Ph.D. (Biochemistry, Sree Chitra Tirunal Institute for Medical Sciences and Technology ), Postdoctoral fellow (Biochemistry, Université de Montréal). Tél.: 514-376-3330, Ext.: 3592
Fatiha Sahmi, Ph.D. (Veterinary Medicine, Université de Montréal), Research Assistant. Tel.: 514-376-3330, Ext.: 3592
Joëlle Trépanier, B.Sc. (Biochemistry and Molecular Medicine, Université de Montréal), MSc student (Biochemistry and Molecular Medicine, Université de Montréal). Tel.: 514-376-3330, Ext.: 3592
G protein-coupled receptor signalling in the nuclear envelope
We demonstrated endothelin (ETB), β-adrenergic (β1AR, β3AR), and angiotensin II (AT1R, AT2R) receptors are present in the membranes of nuclei isolated from rat ventricular myocardium and ventricular myocytes. These receptors were functional with respect to ligand binding and coupled to post-receptor signalling mechanisms including adenylyl cyclase, protein kinases, and IP3 receptor/Ca2+ channels. Most significantly, βAR agonists and angiotensin II were shown to increase de novo RNA synthesis in isolated nuclei whereas ET-1 was inhibitory. The ability of isoproterenol or AngII to increase transcription was blocked by pertussis toxin, implicating Gαi. AT1R-selective, but not AT2R-selective, agonists increased [Ca2+] in isolated nuclei: inhibition of IP3R prevented this Ca2+ influx and attenuated the increase in RNA synthesis induced by AT1R activation. Hence, activation of GPCRs located in the nuclear membranes result in changes in nuclear [Ca2+] that in turn regulate gene expression.
p38 MAP kinase signaling in the heart
There are 4 p38 isoforms: α, β, δ, γ. p38α was thought to be the most abundant isoform expressed in heart. We demonstrated that the abundance of p38γ protein is similar to that of p38α. Furthermore, in response to pressure overload, p38γ relocalized to the nucleus whereas no change in the distribution of p38α was observed. Kinases lying downstream of p38α and p38β include MK2, MK3, and MK5. MK2 and MK5 appear to mediate different detrimental effects of chronic p38 activation (below).
MK2: The physiological function of MK2 includes regulating the expression of inflammatory cytokines. We have now shown that MK2-deficiency results in preserved diastolic function in mouse hearts during chronic pressure overload.
MK5: MK5/PRAK is a protein serine/threonine kinase whose physiological function is currently unknown. MK5 regulation is controversial, as it has been shown to be activated by p38α/β, ERK3 and ERK4. We have recently shown that ERK3, but not ERK4 or p38α, interacts with MK5 in heart. Furthermore, MK5 is involved in mediating the ability of chronic pressure overload to induce an increase in myocardial interstitial fibrosis.
ERK3
ERK3 is an atypical MAP kinase whose upstream regulation and physiological function are currently poorly understood. We have recently shown that ERK3 interacts with MK5 in mouse heart 6 and is involved in mediating the ability of chronic pressure overload to induce an increase in myocardial interstitial fibrosis. Furthermore, ERK3 haploinsufficiency results in increased stiffness of the left ventricular myocardium.
- 2004-2007 : Fonds de la Recherche en Santé du Québec, (FRSQ, Bourse de chercheur-boursier Senior)
- 1999-2004 : Fondation des Maladies du Coeur du Canada, (FMCC, Bourse de chercheur-boursier)
- 1996-1999 : Fonds de la Recherche en Santé du Québec, (FRSQ, Bourse de chercheur-boursier Junior 1)
- 1994-1995 : Alberta Heritage Foundation for Medical Research, (AHFMR, Bourse postdoctorale)
- 1992-1994 : Fondation des Maladies du Coeur du Canada, (FMCC, Bourse postdoctorale)
- 1984-1990 : Fondation des Maladies du Coeur du Canada, (FMCC, Bourse doctorale)
Bruce Allen
514 376-3330, ext. 3591
bruce.g.allen@umontreal.ca
Team members
Bruce G. Allen, Ph.D. (Professor, Dept. of Medicine, Université de Montréal)
Sherine Ali, MD/Ph.D. (Physiology, University of Suez Canal), PhD student (Physiology, Université de Montréal). Tel.: 514-376-3330, Ext.: 3592
Ana Branco, Ph.D. (Bioscience, University of Coimbra), Postdoctoral fellow (Biochemistry, Université de Montréal). Tel.: 514-376-3330, Ext.: 3592
Pramod Sahadevan, Ph.D. (Biochemistry, Sree Chitra Tirunal Institute for Medical Sciences and Technology ), Postdoctoral fellow (Biochemistry, Université de Montréal). Tél.: 514-376-3330, Ext.: 3592
Fatiha Sahmi, Ph.D. (Veterinary Medicine, Université de Montréal), Research Assistant. Tel.: 514-376-3330, Ext.: 3592
Joëlle Trépanier, B.Sc. (Biochemistry and Molecular Medicine, Université de Montréal), MSc student (Biochemistry and Molecular Medicine, Université de Montréal). Tel.: 514-376-3330, Ext.: 3592
Research projects
G protein-coupled receptor signalling in the nuclear envelope
We demonstrated endothelin (ETB), β-adrenergic (β1AR, β3AR), and angiotensin II (AT1R, AT2R) receptors are present in the membranes of nuclei isolated from rat ventricular myocardium and ventricular myocytes. These receptors were functional with respect to ligand binding and coupled to post-receptor signalling mechanisms including adenylyl cyclase, protein kinases, and IP3 receptor/Ca2+ channels. Most significantly, βAR agonists and angiotensin II were shown to increase de novo RNA synthesis in isolated nuclei whereas ET-1 was inhibitory. The ability of isoproterenol or AngII to increase transcription was blocked by pertussis toxin, implicating Gαi. AT1R-selective, but not AT2R-selective, agonists increased [Ca2+] in isolated nuclei: inhibition of IP3R prevented this Ca2+ influx and attenuated the increase in RNA synthesis induced by AT1R activation. Hence, activation of GPCRs located in the nuclear membranes result in changes in nuclear [Ca2+] that in turn regulate gene expression.
p38 MAP kinase signaling in the heart
There are 4 p38 isoforms: α, β, δ, γ. p38α was thought to be the most abundant isoform expressed in heart. We demonstrated that the abundance of p38γ protein is similar to that of p38α. Furthermore, in response to pressure overload, p38γ relocalized to the nucleus whereas no change in the distribution of p38α was observed. Kinases lying downstream of p38α and p38β include MK2, MK3, and MK5. MK2 and MK5 appear to mediate different detrimental effects of chronic p38 activation (below).
MK2: The physiological function of MK2 includes regulating the expression of inflammatory cytokines. We have now shown that MK2-deficiency results in preserved diastolic function in mouse hearts during chronic pressure overload.
MK5: MK5/PRAK is a protein serine/threonine kinase whose physiological function is currently unknown. MK5 regulation is controversial, as it has been shown to be activated by p38α/β, ERK3 and ERK4. We have recently shown that ERK3, but not ERK4 or p38α, interacts with MK5 in heart. Furthermore, MK5 is involved in mediating the ability of chronic pressure overload to induce an increase in myocardial interstitial fibrosis.
ERK3
ERK3 is an atypical MAP kinase whose upstream regulation and physiological function are currently poorly understood. We have recently shown that ERK3 interacts with MK5 in mouse heart 6 and is involved in mediating the ability of chronic pressure overload to induce an increase in myocardial interstitial fibrosis. Furthermore, ERK3 haploinsufficiency results in increased stiffness of the left ventricular myocardium.
Links
Awards and distinctions
- 2004-2007 : Fonds de la Recherche en Santé du Québec, (FRSQ, Bourse de chercheur-boursier Senior)
- 1999-2004 : Fondation des Maladies du Coeur du Canada, (FMCC, Bourse de chercheur-boursier)
- 1996-1999 : Fonds de la Recherche en Santé du Québec, (FRSQ, Bourse de chercheur-boursier Junior 1)
- 1994-1995 : Alberta Heritage Foundation for Medical Research, (AHFMR, Bourse postdoctorale)
- 1992-1994 : Fondation des Maladies du Coeur du Canada, (FMCC, Bourse postdoctorale)
- 1984-1990 : Fondation des Maladies du Coeur du Canada, (FMCC, Bourse doctorale)
Contact
Bruce Allen
514 376-3330, ext. 3591
bruce.g.allen@umontreal.ca