Crohn's disease(CD) is a chronic inflammatory bowel disease that can affect the entire gastrointestinal tract.Ultimately,up to 70% of all patients will need surgery,despite optimized medical therapy.Moreover,about...Crohn's disease(CD) is a chronic inflammatory bowel disease that can affect the entire gastrointestinal tract.Ultimately,up to 70% of all patients will need surgery,despite optimized medical therapy.Moreover,about half of the patients will need redo-surgery because of disease recurrence.The introduction of anti-tumor necrosis factor(TNF) drugs(Infliximab in 1998) revolutionized the treatment of CD.Different randomized trials assessed the efficacy of anti-TNF treatment not only to induce,but also to maintain,steroid-free remission.Furthermore,these agents can rapidly lead to mucosal healing.This aspect is important,as it is a major predictor for long-term disease control.Subgroup analyses of responding patients seemed to suggest a reduction in the need for surgery at median-term follow up(1-3 years).However if one looks at population surveys,one does not observe any decline in the need for surgery since the introduction of Infliximab in 1998.The short follow-up term and the exclusion of patients with imminent surgical need in the randomized trials could bias the results.Only 60% of patients respond to induction of anti-TNF therapy,moreover,some patients will actually develop resistance to biologicals.Many patients are diagnosed when stenosing disease has already occurred,obviating the need for biological therapy.In a further attempt to change the actual course of the disease,top down strategies have been progressively implemented.Whether this will indeed obviate surgery for a substantial group of patients remains unclear.For the time being,surgery will still play a pivotal role in the treatment of CD.展开更多
Dynamic regulation of histone methylation/demethylation plays an important role during development. Mutations and truncations in human plant homeodomain （PHD） finger protein 8 （PHF8） are associated with X-linked m...Dynamic regulation of histone methylation/demethylation plays an important role during development. Mutations and truncations in human plant homeodomain （PHD） finger protein 8 （PHF8） are associated with X-linked mental retardation and facial anomalies, such as a long face, broad nasal tip, cleft lip/cleft palate and large hands, yet its molecular function and structural basis remain unclear. Here, we report the crystal structures of the catalytic core of PHF8 with or without α-ketoglutarate （α-KG） at high resolution. Biochemical and structural studies reveal that PHF8 is a novel histone demethylase specific for di- and mono-methylated histone H3 lysine 9 （H3K9me2/1）, but not for H3K9me3. Our analyses also reveal how human PHF8 discriminates between methylation states and achieves sequence specificity for methylated H3K9. The in vitro demethylation assay also showed that the F279S mutant observed in clinical patients possesses no demethylation activity, suggesting that loss of enzymatic activity is crucial for pathogenesis of PHF8 patients. Taken together, these results will shed light on the molecular mechanism underlying PHF8-associated developmental and neurological diseases.展开更多
Polyglutamine （polyQ） diseases are a family of neurodegenerative disorders including Huntington’s disease, spinobulbar muscular atrophy,dentatorubral-pallidoluysian atrophy and several spinocerebellar ataxias.polyQ...Polyglutamine （polyQ） diseases are a family of neurodegenerative disorders including Huntington’s disease, spinobulbar muscular atrophy,dentatorubral-pallidoluysian atrophy and several spinocerebellar ataxias.polyQ diseases are caused by abnormal expansion of CAG repeats in certain genes.The expanded CAG repeats are then translated into a series of abnormally expanded polyQ tracts.Such polyQ tracts may induce misfolding of the disease-causing proteins.The present review mainly focuses on the common characteristics of the pathogenesis of these polyQ diseases,including conformational transition of proteins and its influence on the function of these proteins,the correlation between decreased ability of proteoly-sis and late-onset polyQ diseases,and the relationship between wide expression of disease-causing proteins and selective neuronal death.展开更多
文摘Crohn's disease(CD) is a chronic inflammatory bowel disease that can affect the entire gastrointestinal tract.Ultimately,up to 70% of all patients will need surgery,despite optimized medical therapy.Moreover,about half of the patients will need redo-surgery because of disease recurrence.The introduction of anti-tumor necrosis factor(TNF) drugs(Infliximab in 1998) revolutionized the treatment of CD.Different randomized trials assessed the efficacy of anti-TNF treatment not only to induce,but also to maintain,steroid-free remission.Furthermore,these agents can rapidly lead to mucosal healing.This aspect is important,as it is a major predictor for long-term disease control.Subgroup analyses of responding patients seemed to suggest a reduction in the need for surgery at median-term follow up(1-3 years).However if one looks at population surveys,one does not observe any decline in the need for surgery since the introduction of Infliximab in 1998.The short follow-up term and the exclusion of patients with imminent surgical need in the randomized trials could bias the results.Only 60% of patients respond to induction of anti-TNF therapy,moreover,some patients will actually develop resistance to biologicals.Many patients are diagnosed when stenosing disease has already occurred,obviating the need for biological therapy.In a further attempt to change the actual course of the disease,top down strategies have been progressively implemented.Whether this will indeed obviate surgery for a substantial group of patients remains unclear.For the time being,surgery will still play a pivotal role in the treatment of CD.
基金Supplementary information is linked to the online version of the paper on the Cell Research website.Acknowledgments We thank Dr Dawei Li （China Agricultural University） for generously providing us with the experimental conditions during the early stages of this project. We thank Dr Ruiming Xu （Institute of Biophysics, Chinese Academy of Sciences） for critical reading of this manuscript and advice. We thank Dr Pinchao Mei （Chinese Academy of Medical Sciences and Peking Union Medical College）, Xinqi Liu （Nankai University） and Jiemin Wong （East China Normal University） for discussions and advice. The synchrotronradiation experiments were performed at Shanghai Synchrotron Radiation Facility （SSRF） and NE3A in the Photon Factory. Z.C. is supported by the National Basic Research Program of China （973 Program, 2009CB825501）, the National Natural Science Foundation of China （30870494 and 90919043）, the New Century Excellent Talents in University （NCET-07-0808） and the Innovative Project of SKLAB. S. H. is supported by the National Key Laboratory Special Fund 2060204. Z. D. is supported by the National Natural Science Foundation of China （J0730639）.
文摘Dynamic regulation of histone methylation/demethylation plays an important role during development. Mutations and truncations in human plant homeodomain （PHD） finger protein 8 （PHF8） are associated with X-linked mental retardation and facial anomalies, such as a long face, broad nasal tip, cleft lip/cleft palate and large hands, yet its molecular function and structural basis remain unclear. Here, we report the crystal structures of the catalytic core of PHF8 with or without α-ketoglutarate （α-KG） at high resolution. Biochemical and structural studies reveal that PHF8 is a novel histone demethylase specific for di- and mono-methylated histone H3 lysine 9 （H3K9me2/1）, but not for H3K9me3. Our analyses also reveal how human PHF8 discriminates between methylation states and achieves sequence specificity for methylated H3K9. The in vitro demethylation assay also showed that the F279S mutant observed in clinical patients possesses no demethylation activity, suggesting that loss of enzymatic activity is crucial for pathogenesis of PHF8 patients. Taken together, these results will shed light on the molecular mechanism underlying PHF8-associated developmental and neurological diseases.
基金supported by the grants from the National Natural Science Foundation of China(No.30600197)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20050285017)
文摘Polyglutamine （polyQ） diseases are a family of neurodegenerative disorders including Huntington’s disease, spinobulbar muscular atrophy,dentatorubral-pallidoluysian atrophy and several spinocerebellar ataxias.polyQ diseases are caused by abnormal expansion of CAG repeats in certain genes.The expanded CAG repeats are then translated into a series of abnormally expanded polyQ tracts.Such polyQ tracts may induce misfolding of the disease-causing proteins.The present review mainly focuses on the common characteristics of the pathogenesis of these polyQ diseases,including conformational transition of proteins and its influence on the function of these proteins,the correlation between decreased ability of proteoly-sis and late-onset polyQ diseases,and the relationship between wide expression of disease-causing proteins and selective neuronal death.
