ABSTRACT
Tripeptidyl peptidase II (TPPII or TPP2) degrades N-terminal tripeptides from proteins and peptides. Studies in both humans and mice have shown that TPPII deficiency is linked to cellular immune-senescence, lifespan regulation and the aging process. However, the mechanism of how TPPII participates in these processes is less clear. In this study, we established a chemical probe-based assay and found that although the mRNA and protein levels of TPPII were not altered during senescence, its enzymatic activity was reduced in senescent human fibroblasts. We also showed that elevation of the levels of the serine protease inhibitor serpinB2 reduced TPPII activity in senescent cells. Moreover, suppression of TPPII led to elevation in the amount of lysosomal contents as in well as TPPI (TPP1) and ß-galactosidase activities, suggesting that lysosome biogenesis is induced to compensate for the reduction of TPPII activity in senescent cells. Together, this study discloses a critical role of the serpinB2-TPPII signaling pathway in proteostasis during senescence. Since serpinB2 levels can be increased by a variety of cellular stresses, reduction of TPPII activity through activation of serpinB2 might represent a common pathway for cells to respond to different stress conditions. This article has an associated First Person interview with the first author of the paper.
Subject(s)
Aminopeptidases , Cellular Senescence , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases , Intracellular Signaling Peptides and Proteins , Aminopeptidases/genetics , Aminopeptidases/metabolism , Cellular Senescence/genetics , Cellular Senescence/physiology , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/genetics , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/metabolism , Fibroblasts/metabolism , Fibroblasts/physiology , Humans , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Proteostasis/genetics , Proteostasis/physiology , Serine Endopeptidases/metabolism , Signal TransductionABSTRACT
We have established a concise synthetic route relying on a key base-promoted epimerization step to synthesize two series of activity-based probes carrying a BODIPY fluorophore for α-l-fucosidase. The resulting probes were evaluated for labeling performance. The one utilizing an o-fluoromethylphenol derivative as the latent trapping unit was successfully applied for the first time to visualize and locate lysosomal α-l-fucosidase activity in human cells.
Subject(s)
Boron Compounds/chemistry , Cell Membrane/chemistry , Phenols/chemistry , alpha-L-Fucosidase/chemistry , Cell Membrane/enzymology , Fluorescence , Humans , KineticsABSTRACT
To facilitate precatalyst recovery and reuse, we have developed a fluorous, oxime-based palladacycle 1 and demonstrated that it is a very efficient and versatile precatalyst for a wide range of carbon-carbon bond formation reactions (Suzuki-Miyaura, Sonogashira, Stille, Heck, Glaser-type, and Kumada) in either aqueous or organic medium under microwave irradiation. Palladacycle 1 could be recovered through F-SPE in various coupling reactions with recovery ranging from 84 to 95% for the first cycle. Inductively coupled plasma optical emission spectrometry (ICP-OES) analyses of the Pd content in the crude product from each class of transformation indicated extremely low levels of leaching and the palladacycle could be reused four to five times without significant loss of activity.
ABSTRACT
Four racemic esters of (1R*,7aR*)-3,6,7,7a-tetrahydro-1-hydroxy-7a-methyl-1H-inden-5(2H)-one were prepared and subjected to hydrolysis with two types of hydrolases, including alcalase and three lipases. Alcalase and lipase showed opposite enantiopreference on these esters. Based on this result, we developed a gram-scale procedure using butanoate as the substrate, which was treated consecutively with alcalase and lipase from Candida rugosa (CRL), to give both enantiomers of the title compound in high yields and high enantiomeric excess.
Subject(s)
Indenes/chemistry , Indenes/isolation & purification , Candida/enzymology , Indenes/chemical synthesis , Lipase/metabolism , Stereoisomerism , Substrate Specificity , Subtilisins/metabolismABSTRACT
We have developed a convenient chemoenzymatic method for the preparation of (4aS,5S)-4,4a,5,6,7,8-hexahydro-5-hydroxy-4a-methylnaphthalen-2(3H)-one by taking advantage of the excellent enantioselectivity of alcalase. Four different esters were compared, and the butanoate ester was found to be the best substrate. The stereochemistry of the product is the same as the one predicted from the binding model of alcalase. A simple extraction/partition procedure was used to separate the hydroxyenone product from the remaining ester. This practical procedure would be very useful in a gram-scale operation for securing the title compound in high optical purity.