Identification of Ubiquitinated Proteins from Human Multiple Myeloma U266 Cells by Proteomics

Objective To identify ubiquitinated proteins from complex human multiple myeloma （MM） U266 cells,a malignant disorder of differentiated human B cells.Methods Employing a globally proteomic strategy combining of immunoprecipitation,LC-MS/MS and SCX-LC-MS analysis to identified ubiquitination sites,which were identified by detecting signature peptides containing a GG-tag （114.1 Da） and an LRGG-tag （383.2 Da）.Results In total,52 ubiquitinated proteins containing 73 ubiquitination sites of which 14 and 59 sites contained LRGG-tag and GG-tag were identified,respectively.Conclusion Classification analysis by of the proteins identified in the study based on the PANTHER showed that they were associated with multiple functional groups.This suggested the involvement of many endogenous proteins in the ubiquitination in MM.

The role of 5′-adenosine monophosphate-activated protein kinase(AMPK)in skeletal muscle atrophy

As a key coordinator of metabolism,AMP-activated protein kinase(AMPK)is vitally involved in skeletal muscle maintenance.AMPK exerts its cellular effects through its function as a serine/threonine protein kinase by regulating many downstream targets and plays important roles in the development and growth of skeletal muscle.AMPK is activated by phosphorylation and exerts its function as a kinase in many processes,including synthesis and degradation of proteins,mitochondrial biogenesis,glucose uptake,and fatty acid and cholesterol metabolism.Skeletal muscle atrophy is a result of various diseases or disorders and is characterized by a decrease in muscle mass.The pathogenesis and therapeutic strategies of skeletal muscle atrophy are still under investigation.In this review,we discuss the role of AMPK in skeletal muscle metabolism and atrophy.We also discuss targeting AMPK for skeletal muscle treatment,including exercise,AMPK activators including 5-amino-4-imidazolecarboxamide ribonucleoside and metformin,and low-level lasers.These studies show the important roles of AMPK in regulating muscle metabolism and function;thus,the treatment of skeletal muscle atrophy needs to take into account the roles of AMPK.

A novel missense mutation of the ubiquitin protein ligase E3A gene in a patient with Angelman syndrome

Background Angelman syndrome （AS） is a neurogenetic disorder caused by an expression defect of the maternally inherited copy of ubiquitin protein ligase E3A （UBE3A） gene from chromosome 15. Although the most common genetic defects include maternal deletions of chromosome 15q11-13, paternal uniparental disomy and imprinting defect, mutations in the UBE3A gene have been identified in approximately 10% of AS patients. Methods A Chinese girl of 28 months presented clinical manifestation of AS. Genetic diagnosis and molecular genetic defects were studied by methylation-specific PCR （MS-PCR） and linkage analysis by short tandem repeat （STR）. We further performed sequence analysis of all the coding exons and flanking sequences of the UBE3A gene. The novel mutation screening was also performed in 100 unrelated healthy individuals to exclude the possibility of identifying a polymorphism variation. Results The MS-PCR analysis of the patient showed biparental inheritance of chromosome 15 with a normal methylation pattern in the 15q11-q13 region. And STR analysis revealed that the patient also inherited biparental alleles for six microsatellites. A novel mutation, cDNA1199 C〉A （p.P400H）, in exon 9 of the maternal UBE3A gene, was identified in the patient. Meanwhile, the mutation was observed in the patient＇s mother who had a normal phenotype. Conclusions It is necessary to perform the UBE3A gene mutation analysis in non-deletion/non-UPD/non-ID patients with AS. The clinical picture of the patient is concordant with that observed in previously reported AS patients with UBE3A mutation.

PLMD：An updated data resource of protein lysine modifications

Post-translational modifications（PTMs） occurring at protein lysine residues,or protein lysine modifications（PLMs）,play critical roles in regulating biological processes.Due to the explosive expansion of the amount of PLM substrates and the discovery of novel PLM types,here we greatly updated our previous studies,and presented a much more integrative resource of protein lysine modification database（PLMD）.In PLMD,we totally collected and integrated 284,780 modification events in 53,501 proteins across 176 eukaryotes and prokaryotes for up to 20 types of PLMs,including ubiquitination, acetylation, sumoylation, methylation ,succinylation,malonylation,glutarylation,giycation,formylation,hydroxylation,butyrylation,propionylation,crotonylation,pupylation,neddylation,2-hydroxyisobutyrylation,phosphoglycerylation,carboxylation,lipoylation and biotinylation.Using the data set,a motif-based analysis was performed for each PLM type,and the results demonstrated that different PLM types preferentially recognize distinct sequence motifs for the modifications.Moreover,various PLMs synergistically orchestrate specific cellular biological processes by mutual crosstalks with each other,and we totally found 65,297 PLM events involved in 90 types of PLM co-occurrences on the same lysine residues.Finally,various options were provided for accessing the data,while original references and other annotations were also present for each PLM substrate.Taken together,we anticipated the PLMD database can serve as a useful resource for further researches of PLMs.PLMD 3.0 was implemented in PHP ＋ MySQL and freely available at http：//plmd.biocuckoo.org.