Project description:Previous studies have suggested that the heart may be capable of limited repair and regeneration in response to a focal injury while other studies indicate that the mammalian heart has no regenerative capacity. To further explore this issue, we performed a series of superficial and transmural myocardial injuries in C57BL/6 and MRL/MpJ adult mice. At defined time intervals following the respective injury (Days 3, 14, 30 and 60) we examined cardiac function using echocardiography, morphology, FACS cell sorting for BrdU positive cells and molecular signature using microarray analysis. We observed complete restoration of myocardial function in the superficial MRL cryoinjured heart and significantly less scar formation as compared to the injured hearts of C57BL/6 mice. Following a severe transmural myocardial injury, the MRL mouse has increased survival and decreased ventricular remodeling compared to the C57BL/6 mouse but without evidence of significant regeneration. The cytoprotective program observed in the severely injured MRL heart is in part due to increased vasculogenesis and decreased apoptosis that limits the extension of the injury. We conclude that C57BL/6 and MRL injured hearts have evidence of limited myocardial regeneration, in response to superficial injury, but the improved function and survival observed in the MRL mouse heart following severe injury is not due to significant regenerative processes. Mouse hearts from C57BL/6 and MRL/MpJ strains were injured with LAD ligation and harvested at 3, 30 and 60 days after treatement.
Project description:Previous studies have suggested that the heart may be capable of limited repair and regeneration in response to a focal injury while other studies indicate that the mammalian heart has no regenerative capacity. To further explore this issue, we performed a series of superficial and transmural myocardial injuries in C57BL/6 and MRL/MpJ adult mice. At defined time intervals following the respective injury (Days 3, 14, 30 and 60) we examined cardiac function using echocardiography, morphology, FACS cell sorting for BrdU positive cells and molecular signature using microarray analysis. We observed complete restoration of myocardial function in the superficial MRL cryoinjured heart and significantly less scar formation as compared to the injured hearts of C57BL/6 mice. Following a severe transmural myocardial injury, the MRL mouse has increased survival and decreased ventricular remodeling compared to the C57BL/6 mouse but without evidence of significant regeneration. The cytoprotective program observed in the severely injured MRL heart is in part due to increased vasculogenesis and decreased apoptosis that limits the extension of the injury. We conclude that C57BL/6 and MRL injured hearts have evidence of limited myocardial regeneration, in response to superficial injury, but the improved function and survival observed in the MRL mouse heart following severe injury is not due to significant regenerative processes. Keywords: time course
Project description:Animal models have enhanced our understanding of the pathogenesis of autoimmune diseases. For these models, genetically identical, inbred mice have commonly been used. Different inbred mouse strains, however, show a high variability in disease manifestation. Identifying the factors that influence this disease variability could provide unrecognized insights into pathogenesis. We established a novel antibody transfer-induced model of epidermolysis bullosa acquisita (EBA), an autoimmune disease characterized by (muco)-cutaneous blistering caused by anti-type VII collagen (COL7) autoantibodies. Blistering after anti-COL7 IgG (directed against the von-Willebrand-factor A like domain 2) transfer showed clear variability among inbred mouse strains; i.e. severe cutaneous blistering and inflammation in C57Bl/6J, and absence of skin lesions in MRL/MpJ mice. The transfer of anti-COL7 IgG into irradiated, EBA-resistant MRL/MpJ mice, rescued by transplantation with bone marrow from EBA-susceptible B6.AK-H2k mice, induced blistering. To the contrary, irradiated EBA-susceptible B6.AK-H2k mice that were rescued using MRL/MpJ bone marrow were devoid of blistering. In vitro, immune complex activation of neutrophils from C57Bl/6J or MRL/MpJ mice showed an impaired ROS release from the latter, whereas no differences were observed after PMA activation. This finding was paralleled by divergent expression profiles of immune-complex activated neutrophils from either C57Bl/6J or MRL/MpJ mice. Collectively, we demonstrate that radiosensitive cells determine the varying extent of skin inflammation and blistering in the end-stage effector phase of EBA. We used microarray to differentiate between the molecular response for the immune complex stimulated neutrophils in MRL/MpJ and C57Bl/6J mice To unravel the molecular basis for the different response to immune complex (IC) stimulation between MRL/MpJ and C57Bl/6J mice, the cells were activated using IC, and differential expression using microarray was compared between resting or activated neutrophils from MRL/MpJ or C57Bl/6J mice.
Project description:Animal models have enhanced our understanding of the pathogenesis of autoimmune diseases. For these models, genetically identical, inbred mice have commonly been used. Different inbred mouse strains, however, show a high variability in disease manifestation. Identifying the factors that influence this disease variability could provide unrecognized insights into pathogenesis. We established a novel antibody transfer-induced model of epidermolysis bullosa acquisita (EBA), an autoimmune disease characterized by (muco)-cutaneous blistering caused by anti-type VII collagen (COL7) autoantibodies. Blistering after anti-COL7 IgG (directed against the von-Willebrand-factor A like domain 2) transfer showed clear variability among inbred mouse strains; i.e. severe cutaneous blistering and inflammation in C57Bl/6J, and absence of skin lesions in MRL/MpJ mice. The transfer of anti-COL7 IgG into irradiated, EBA-resistant MRL/MpJ mice, rescued by transplantation with bone marrow from EBA-susceptible B6.AK-H2k mice, induced blistering. To the contrary, irradiated EBA-susceptible B6.AK-H2k mice that were rescued using MRL/MpJ bone marrow were devoid of blistering. In vitro, immune complex activation of neutrophils from C57Bl/6J or MRL/MpJ mice showed an impaired ROS release from the latter, whereas no differences were observed after PMA activation. This finding was paralleled by divergent expression profiles of immune-complex activated neutrophils from either C57Bl/6J or MRL/MpJ mice. Collectively, we demonstrate that radiosensitive cells determine the varying extent of skin inflammation and blistering in the end-stage effector phase of EBA. We used microarray to differentiate between the molecular response for the immune complex stimulated neutrophils in MRL/MpJ and C57Bl/6J mice
Project description:Epigenetic regulation plays essential role in cell differentiation and dedifferentiation, which are the intrinsic processes involved in regeneration. In order to investigate the epigenetic basis of regeneration capacity, we choose DNA methylation as one of the most important epigenetic mechanisms and the MRL/MpJ mouse as a model of mammalian regeneration reported to exhibit enhanced regeneration response in different organs. We report the comparative analysis of genomic DNA methylation profiles of the MRL/MpJ and the control C57BL/6J mouse. Methylated DNA immunoprecipitation (MeDIP) followed by microarray analysis using Nimblegen M-bM-^@M-^\3x720K CpG Island Plus RefSeq PromoterM-bM-^@M-^] platform were applied in order to carry out genome-wide DNA methylation profiling covering 20,404 promoter regions. We identified hundreds of hypo- and hypermethylated genes and CpG islands in heart, liver and spleen, and 37 of them in the three tissues. Decreased inter-tissue diversification and the shift of DNA methylation balance upstream the genes distinguish the genomic methylation patterns of the MRL/MpJ mouse from the C57BL/6J. Homeobox genes and a number of other genes involved in embryonic morphogenesis are significantly over-represented among the genes hypomethylated in the MRL/MpJ mouse. These findings indicate that epigenetic patterning might be a likely molecular basis of regeneration capability in the MRL/MpJ mouse. genome-wide DNA methylation profiling in the heart, liver, and spleen tissues of MRL/MpJ and C57BL/6J mouse
Project description:The Murphy Roth Large (MRL) mouse, a strain capable of regenerating right ventricular myocardium, has a high post-myocardial infarction (MI) survival rate compared with C57BL6/J (C57) mice. The biological processes responsible for this survival advantage are unknown. We compared acute post-MI gene expression in C57 and MRL hearts using microarrays and identified promising candidate biological processes underlying increased survival in the MRL.
Project description:Epigenetic regulation plays essential role in cell differentiation and dedifferentiation, which are the intrinsic processes involved in regeneration. In order to investigate the epigenetic basis of regeneration capacity, we choose DNA methylation as one of the most important epigenetic mechanisms and the MRL/MpJ mouse as a model of mammalian regeneration reported to exhibit enhanced regeneration response in different organs. We report the comparative analysis of genomic DNA methylation profiles of the MRL/MpJ and the control C57BL/6J mouse. Methylated DNA immunoprecipitation (MeDIP) followed by microarray analysis using Nimblegen “3x720K CpG Island Plus RefSeq Promoter” platform were applied in order to carry out genome-wide DNA methylation profiling covering 20,404 promoter regions. We identified hundreds of hypo- and hypermethylated genes and CpG islands in heart, liver and spleen, and 37 of them in the three tissues. Decreased inter-tissue diversification and the shift of DNA methylation balance upstream the genes distinguish the genomic methylation patterns of the MRL/MpJ mouse from the C57BL/6J. Homeobox genes and a number of other genes involved in embryonic morphogenesis are significantly over-represented among the genes hypomethylated in the MRL/MpJ mouse. These findings indicate that epigenetic patterning might be a likely molecular basis of regeneration capability in the MRL/MpJ mouse.
Project description:The aim of the study was to find genomic regions that show differences in DNA methylation status between the MRL/MpJ mouse, which show enhanced regeneration response, and two control mouse strains C57BL/6J and BALB/c.
Project description:Cryptorchidism and scrotal heating result in abnormal spermatogenesis but the mechanism(s) proscribing this temperature sensitivity are unknown. It was previously reported that the AKR/N or MRL/MpJ-+/+ mouse testis is more heat resistant than the testis from the C57BL/6 strain. We have attempted to probe into the mechanism(s) involved in heat sensitivity by examining global gene expression profiles of normal and heat-treated testes from C57BL/6, AKR/N and MRL/MpJ-+/+ mice by microarray analysis. In the normal C57BL/6 testis, 415 and 416 transcripts were differentially expressed (at least two-fold higher or lower) when compared to the normal AKR/N and MRL/MpJ-+/+ testis, respectively. The AKR/N and MRL/MpJ-+/+ strains revealed 268 differentially expressed transcripts between them. There were 231 transcripts differentially expressed between C57BL/6 and two purported heat-resistant strains, AKR/N and MRL/MpJ-+/+.