Mesenchymal stem cells （MSCs） are considered as the developmental origin of multiple Uneage cells including osteocytes, adipocytes, and muscle cells. Previous studies demonstrated that the PH domain.containing prote...Mesenchymal stem cells （MSCs） are considered as the developmental origin of multiple Uneage cells including osteocytes, adipocytes, and muscle cells. Previous studies demonstrated that the PH domain.containing protein CKIP-1 plays an important role in the devel- opment of osteobiasts and cardiomyocytes. However, whether CKIP-1 is involved in the generation of adipocytes as weU as the MSC differentiation remains unknown. Here we show that CKIP-1 is a novel regulator of MSCs differentiating into adipocytes. MSCs derived from CKIP-l-deficient mice display enhanced adipogenesis upon induction. Further analysis showed that CKIP-1 interacts with the histone deacetylase HDAC1 in the nucleus and inhibits the transcription of CCAAT/enhancer-binding protein α （C/EBPcx）, which is a crucial adipogenic transcription factor. Ectopic expression of CKI P-1 in a MSC-Uke cell line C3H/10T1/2 reduced the gener- ation of adipocytes due to suppression of adipogenic factors, including C/EBPα. Moreover, CKI P-l-deficient mice showed an increase in body weight and white adipose tissue gains when fed on a high-fat diet. Collectively, these results suggest that CKIP-1 is a novel inhibitor of MSC-originated adipogenesis by enhancing HDACl-associated repression of C/EBPα.展开更多
Ribosomes are among the most fundamental molecular machines in all cells,as they are required for protein synthesis.Most structural rRNA components are generated in the nucleolus and assembled into pre-ribosomal parti...Ribosomes are among the most fundamental molecular machines in all cells,as they are required for protein synthesis.Most structural rRNA components are generated in the nucleolus and assembled into pre-ribosomal particles.Here we show Apak,a previously identified p53 inhibitor,as a novel ribosomal stress response protein.In unstressed cells,Apak is bound to the deSUMOylase SENP1 in the nucleoplasm and targeted for proteasomal degradation by MDM2 ubiquitin ligase.Upon ribosomal stress,SENP1 dissociates fromApak and the tumor suppressor protein ARF couplesUbc9 with Apak to promote Apak SUMOylation on zinc fingers.This results in Apak protein stabilization and translocation to the nucleolus,where Apak inhibits the pre-rRNA synthesis.These findings provide a molecular mechanism whereby ARF coordinates Apak to regulate ribosome biogenesis upon cellular stress.展开更多
文摘Mesenchymal stem cells （MSCs） are considered as the developmental origin of multiple Uneage cells including osteocytes, adipocytes, and muscle cells. Previous studies demonstrated that the PH domain.containing protein CKIP-1 plays an important role in the devel- opment of osteobiasts and cardiomyocytes. However, whether CKIP-1 is involved in the generation of adipocytes as weU as the MSC differentiation remains unknown. Here we show that CKIP-1 is a novel regulator of MSCs differentiating into adipocytes. MSCs derived from CKIP-l-deficient mice display enhanced adipogenesis upon induction. Further analysis showed that CKIP-1 interacts with the histone deacetylase HDAC1 in the nucleus and inhibits the transcription of CCAAT/enhancer-binding protein α （C/EBPcx）, which is a crucial adipogenic transcription factor. Ectopic expression of CKI P-1 in a MSC-Uke cell line C3H/10T1/2 reduced the gener- ation of adipocytes due to suppression of adipogenic factors, including C/EBPα. Moreover, CKI P-l-deficient mice showed an increase in body weight and white adipose tissue gains when fed on a high-fat diet. Collectively, these results suggest that CKIP-1 is a novel inhibitor of MSC-originated adipogenesis by enhancing HDACl-associated repression of C/EBPα.
基金This research was supported by grants from the National Basic Research Program of China(2011CB910802,2013CB910803,2012CB910702)the National Natural Science Foundation of China(31125010,81221004).
文摘Ribosomes are among the most fundamental molecular machines in all cells,as they are required for protein synthesis.Most structural rRNA components are generated in the nucleolus and assembled into pre-ribosomal particles.Here we show Apak,a previously identified p53 inhibitor,as a novel ribosomal stress response protein.In unstressed cells,Apak is bound to the deSUMOylase SENP1 in the nucleoplasm and targeted for proteasomal degradation by MDM2 ubiquitin ligase.Upon ribosomal stress,SENP1 dissociates fromApak and the tumor suppressor protein ARF couplesUbc9 with Apak to promote Apak SUMOylation on zinc fingers.This results in Apak protein stabilization and translocation to the nucleolus,where Apak inhibits the pre-rRNA synthesis.These findings provide a molecular mechanism whereby ARF coordinates Apak to regulate ribosome biogenesis upon cellular stress.
