Ischemic brain injury triggers an inflammatory response. tissue but can also exacerbate brain injury. Microglia are This response is necessary to clear damaged brain the innate immune cells of the brain that execute t...Ischemic brain injury triggers an inflammatory response. tissue but can also exacerbate brain injury. Microglia are This response is necessary to clear damaged brain the innate immune cells of the brain that execute this critical function. In healthy brain, microglia perform a housekeeping function, pruning unused syn- apses between neurons. However, microglia become activated to an inflammatory phenotype upon brain injury. Interferon regulatory factors modulate microglial activation and their production of inflammatory cytokines. This review briefly discusses recent findings pertaining to these regulatory mechanisms in the context of stroke recovery.展开更多
Interferon Regulatory Factor-2 (IRF-2) belongs to IRF family, was identified as a mammalian transcription factor involved in Interferon beta (IFNβ) gene regulation. Besides that IRF-2 is involved in immunomodulation,...Interferon Regulatory Factor-2 (IRF-2) belongs to IRF family, was identified as a mammalian transcription factor involved in Interferon beta (IFNβ) gene regulation. Besides that IRF-2 is involved in immunomodulation, hematopoietic differentiation, cell cycle regulation and oncogenesis. We have done molecular sub-cloning and expression of recombinant murine IRF-2 as GST (Glutathione-S-Transferase)- IRF-2 fusion protein in E. coli/XL-1blue cells. Recombinant IRF-2 with GST moiety at N-terminus expressed as GST-IRF-2 (~66 kd) in E. coli along with different low molecular mass degradation products revealed approximately 30, 42, 60 and 62 kd by SDS-PAGE and Western blot, respectively. We further confirm that degradation takes place at C-terminus of the fusion protein not at N-terminus as anti-GST antibody was detecting all bands in the immunoblot. The recombinant IRF-2 was biologically active along with their degradation products in terms of their DNA binding activity as assessed by Electrophoretically Mobility Shift Assay (EMSA). We observed three different molecular mass DNA/protein complexes (1 - 3) with Virus Response Element (VRE) derived from human Interferon IFNβ gene and five different molecular mass complexes (1 - 5) with IRF-E motif (GAAAGT)4 in EMSA gel. GST only expressed from empty vector did not bind to these DNA elements. To confirm that the binding is specific, all complexes were competed out completely when challenged with 100-X fold molar excess of IRF-E oligo under cold competition. It means degradation products along with full-length protein are able to interact with VREβ as well as IRF-E motif. This means degradation products may regulate the target gene (s) activation/repression via interacting with VRE/IRF-E.展开更多
The molecular mechanism of how hepatocytes maintain cholesterol homeostasis has become much more transparent with the discovery of sterol regulatory element binding proteins (SREBPs) in recent years. These membrane pr...The molecular mechanism of how hepatocytes maintain cholesterol homeostasis has become much more transparent with the discovery of sterol regulatory element binding proteins (SREBPs) in recent years. These membrane proteins aremembers of the basic helix-loop-helix-leucine zipper (bHLHZip) family of transcription factors. They activate the expression of at least 30 genes involved in the synthesis of cholesterol and lipids. SREBPs are synthesized as precursor proteins in the endoplasmic reticulum (ER), where they form a complex with another protein, SREBP cleavage activating protein (SCAP). The SCAP molecule contains a sterol sensory domain. In the presence of high cellular sterol concentrations SCAP confines SREBP to the ER. With low cellular concentrations, SCAP escorts SREBP to activation in the Golgi. There, SREBP undergoes two proteolytic cleavage steps to release the mature, biologically active transcription factor, nuclear SREBP (nSREBP). nSREBP translocates to the nucleus and binds to sterol response elements (SRE) in the promoter/enhancer regions of target genes. Additional transcription factors are required to activate transcription of these genes. Three different SREBPs are known, SREBPs-1a, -1c and -2. SREBP-1a and -1c are isoforms produced from a single gene by alternate splicing. SREBP-2 is encoded by a different gene and does not display any isoforms. It appears that SREBPs alone, in the sequence described above, can exert complete control over cholesterol synthesis, whereas many additional factors (hormones, cytokines, etc.) are required for complete control of lipid metabolism. Medicinal manipulation of the SREBP/SCAP system is expected to prove highly beneficial in the management of cholesterol-related disease.展开更多
Heart diseases are the main cause of mortality in Mexico, being coronary </span><span style="font-family:Verdana;">heart disease the most frequent in the country. Its high prevalence makes i...Heart diseases are the main cause of mortality in Mexico, being coronary </span><span style="font-family:Verdana;">heart disease the most frequent in the country. Its high prevalence makes important </span><span style="font-family:Verdana;">the study of the pathophysiology and the search for prognostic </span><span style="font-family:Verdana;">factors. Different genes and polymorphisms promote atherogenesis and coronary artery disease, they affect inflammatory and vascular pathological processes. </span><span style="font-family:Verdana;">Interferon regulatory factor 5 (IRF5) is associated with coronary heart disease, it promotes chronic inflammation and cytokines release;it could trigger immune reactions and its activating receptors express in the vascular endothelium. Besides, polymorphisms in the renin-angiotensin-aldosterone system (RAAS) are implied with coronary disease, they are found in angiotensinogen (AGT), angiotensin II type 1 receptor (AT1R), angiotensin II type 2 receptor (AT2R), and angiotensin-converting enzyme (ACE) genes. These genetic polymorphisms are associated with a prothrombotic state, endothelial dysfunction, and immune activation. Multiple experimental studies showed that chronic activation of RAAS and chronic expression of IRF5 generates an environment prone to the development of atherosclerosis, and autoimmune and cardiovascular diseases. Studying these specific genes and their relationship with coronary heart disease will allow a better understanding of the pathological process and possibly the quest for new treatments.展开更多
There is a major transformation in gene expression between mature B cells (including follicular, marginal zone, and germinal center cells) and antibody secreting cells (ASCs), i.e. , ASCs, (including plasma blas...There is a major transformation in gene expression between mature B cells (including follicular, marginal zone, and germinal center cells) and antibody secreting cells (ASCs), i.e. , ASCs, (including plasma blasts, splenic plasma cells, and long-lived bone marrow plasma cells). This signifcant change-over occurs to accommodate the massive amount of secretory-specific immunoglobulin that ASCs make and the export processes itself. It is well known that there is an up-regulation of a small number of ASC-specific transcription factors Prdm1 (B-lymphocyte-induced maturation protein 1), interferon regulatory factor 4, and Xbp1, and the reciprocal down-regulation of Pax5, Bcl6 and Bach2, which maintain the B cell program. Less well appreciated are the major alterations in transcription elongation and RNA proce-ssing occurring between B cells and ASCs. The three ELL family members ELL1, 2 and 3 have different protein sequences and potentially distinct cellular roles in transcription elongation. ELL1 is involved in DNA repair and small RNAs while ELL3 was previously described as either testis or stem-cell specifc. After B cell stimulation to ASCs, ELL3 levels fall precipitously while ELL1 falls off slightly. ELL2 is induced at least 10-fold in ASCs relative to B cells. All of these changes cause the RNA Polymerase Ⅱ in ASCs to acquire different properties, leading to differences in RNA processing and histone modifcations.展开更多
基金supported by a grant from the Heart and Stroke Foundation of Canada(HHC,AFRS)a grant from the Natural Science&Engineering Research Council of Canada(HHC,AFRS)a Mid-Career Investigator Award from the Heart and Stroke Foundation of Ontario,Canada(HHC)
文摘Ischemic brain injury triggers an inflammatory response. tissue but can also exacerbate brain injury. Microglia are This response is necessary to clear damaged brain the innate immune cells of the brain that execute this critical function. In healthy brain, microglia perform a housekeeping function, pruning unused syn- apses between neurons. However, microglia become activated to an inflammatory phenotype upon brain injury. Interferon regulatory factors modulate microglial activation and their production of inflammatory cytokines. This review briefly discusses recent findings pertaining to these regulatory mechanisms in the context of stroke recovery.
文摘Interferon Regulatory Factor-2 (IRF-2) belongs to IRF family, was identified as a mammalian transcription factor involved in Interferon beta (IFNβ) gene regulation. Besides that IRF-2 is involved in immunomodulation, hematopoietic differentiation, cell cycle regulation and oncogenesis. We have done molecular sub-cloning and expression of recombinant murine IRF-2 as GST (Glutathione-S-Transferase)- IRF-2 fusion protein in E. coli/XL-1blue cells. Recombinant IRF-2 with GST moiety at N-terminus expressed as GST-IRF-2 (~66 kd) in E. coli along with different low molecular mass degradation products revealed approximately 30, 42, 60 and 62 kd by SDS-PAGE and Western blot, respectively. We further confirm that degradation takes place at C-terminus of the fusion protein not at N-terminus as anti-GST antibody was detecting all bands in the immunoblot. The recombinant IRF-2 was biologically active along with their degradation products in terms of their DNA binding activity as assessed by Electrophoretically Mobility Shift Assay (EMSA). We observed three different molecular mass DNA/protein complexes (1 - 3) with Virus Response Element (VRE) derived from human Interferon IFNβ gene and five different molecular mass complexes (1 - 5) with IRF-E motif (GAAAGT)4 in EMSA gel. GST only expressed from empty vector did not bind to these DNA elements. To confirm that the binding is specific, all complexes were competed out completely when challenged with 100-X fold molar excess of IRF-E oligo under cold competition. It means degradation products along with full-length protein are able to interact with VREβ as well as IRF-E motif. This means degradation products may regulate the target gene (s) activation/repression via interacting with VRE/IRF-E.
文摘The molecular mechanism of how hepatocytes maintain cholesterol homeostasis has become much more transparent with the discovery of sterol regulatory element binding proteins (SREBPs) in recent years. These membrane proteins aremembers of the basic helix-loop-helix-leucine zipper (bHLHZip) family of transcription factors. They activate the expression of at least 30 genes involved in the synthesis of cholesterol and lipids. SREBPs are synthesized as precursor proteins in the endoplasmic reticulum (ER), where they form a complex with another protein, SREBP cleavage activating protein (SCAP). The SCAP molecule contains a sterol sensory domain. In the presence of high cellular sterol concentrations SCAP confines SREBP to the ER. With low cellular concentrations, SCAP escorts SREBP to activation in the Golgi. There, SREBP undergoes two proteolytic cleavage steps to release the mature, biologically active transcription factor, nuclear SREBP (nSREBP). nSREBP translocates to the nucleus and binds to sterol response elements (SRE) in the promoter/enhancer regions of target genes. Additional transcription factors are required to activate transcription of these genes. Three different SREBPs are known, SREBPs-1a, -1c and -2. SREBP-1a and -1c are isoforms produced from a single gene by alternate splicing. SREBP-2 is encoded by a different gene and does not display any isoforms. It appears that SREBPs alone, in the sequence described above, can exert complete control over cholesterol synthesis, whereas many additional factors (hormones, cytokines, etc.) are required for complete control of lipid metabolism. Medicinal manipulation of the SREBP/SCAP system is expected to prove highly beneficial in the management of cholesterol-related disease.
文摘Heart diseases are the main cause of mortality in Mexico, being coronary </span><span style="font-family:Verdana;">heart disease the most frequent in the country. Its high prevalence makes important </span><span style="font-family:Verdana;">the study of the pathophysiology and the search for prognostic </span><span style="font-family:Verdana;">factors. Different genes and polymorphisms promote atherogenesis and coronary artery disease, they affect inflammatory and vascular pathological processes. </span><span style="font-family:Verdana;">Interferon regulatory factor 5 (IRF5) is associated with coronary heart disease, it promotes chronic inflammation and cytokines release;it could trigger immune reactions and its activating receptors express in the vascular endothelium. Besides, polymorphisms in the renin-angiotensin-aldosterone system (RAAS) are implied with coronary disease, they are found in angiotensinogen (AGT), angiotensin II type 1 receptor (AT1R), angiotensin II type 2 receptor (AT2R), and angiotensin-converting enzyme (ACE) genes. These genetic polymorphisms are associated with a prothrombotic state, endothelial dysfunction, and immune activation. Multiple experimental studies showed that chronic activation of RAAS and chronic expression of IRF5 generates an environment prone to the development of atherosclerosis, and autoimmune and cardiovascular diseases. Studying these specific genes and their relationship with coronary heart disease will allow a better understanding of the pathological process and possibly the quest for new treatments.
基金Supported by The National Science Foundation grant MCB-08-42725National Institutes of Health shared resources Grant No.P30CA047904 to the University of Pittsburgh Cancer Instituteinternal funding from the School of Medicine and Department of Immunology
文摘There is a major transformation in gene expression between mature B cells (including follicular, marginal zone, and germinal center cells) and antibody secreting cells (ASCs), i.e. , ASCs, (including plasma blasts, splenic plasma cells, and long-lived bone marrow plasma cells). This signifcant change-over occurs to accommodate the massive amount of secretory-specific immunoglobulin that ASCs make and the export processes itself. It is well known that there is an up-regulation of a small number of ASC-specific transcription factors Prdm1 (B-lymphocyte-induced maturation protein 1), interferon regulatory factor 4, and Xbp1, and the reciprocal down-regulation of Pax5, Bcl6 and Bach2, which maintain the B cell program. Less well appreciated are the major alterations in transcription elongation and RNA proce-ssing occurring between B cells and ASCs. The three ELL family members ELL1, 2 and 3 have different protein sequences and potentially distinct cellular roles in transcription elongation. ELL1 is involved in DNA repair and small RNAs while ELL3 was previously described as either testis or stem-cell specifc. After B cell stimulation to ASCs, ELL3 levels fall precipitously while ELL1 falls off slightly. ELL2 is induced at least 10-fold in ASCs relative to B cells. All of these changes cause the RNA Polymerase Ⅱ in ASCs to acquire different properties, leading to differences in RNA processing and histone modifcations.