Decoding the role of angiopoietin-like protein 4/8 complex-mediated plasmin generation in the regulation of LPL activity.

After feeding, adipose tissue lipoprotein lipase (LPL) activity should be maximized, therefore the potent LPL-inhibitory activity of angiopoietin-like protein 4 (ANGPTL4) must be blocked by ANGPTL8 through formation of ANGPTL4/8 complexes. ANGPTL4/8 tightly binds and protects LPL but also partially inhibits its activity. Recently, we demonstrated ANGPTL4/8 also binds tissue plasminogen activator (tPA) and plasminogen to generate plasmin that cleaves ANGPTL4/8 to restore LPL activity.

Angiopoietin-like protein 4/8 complex-mediated plasmin generation leads to cleavage of the complex and restoration of LPL activity.

Triglyceride (TG) metabolism is highly regulated by angiopoietin-like protein (ANGPTL) family members [Y. Q. Chen ,  , 1203-1220 (2020)].

An anti-ANGPTL3/8 antibody decreases circulating triglycerides by binding to a LPL-inhibitory leucine zipper-like motif.

Triglycerides (TG) are required for fatty acid transport and storage and are essential for human health. Angiopoietin-like-protein 8 (ANGPTL8) has previously been shown to form a complex with ANGPTL3 that increases circulating TG by potently inhibiting LPL. We also recently showed that the TG-lowering apolipoprotein A5 (ApoA5) decreases TG levels by suppressing ANGPTL3/8-mediated LPL inhibition.

ApoA5 lowers triglyceride levels via suppression of ANGPTL3/8-mediated LPL inhibition.

Triglyceride (TG) molecules represent the major storage form of fatty acids, and TG metabolism is essential to human health. However, the mechanistic details surrounding TG metabolism are complex and incompletely elucidated. Although it is known that angiopoietin-like protein 8 (ANGPTL8) increases TGs through an ANGPTL3/8 complex that inhibits LPL, the mechanism governing ApoA5, which lowers TGs, has remained elusive.

Angiopoietin-like protein 8 differentially regulates ANGPTL3 and ANGPTL4 during postprandial partitioning of fatty acids.

Angiopoietin-like protein (ANGPTL)8 has been implicated in metabolic syndrome and reported to regulate adipose FA uptake through unknown mechanisms. Here, we studied how complex formation of ANGPTL8 with ANGPTL3 or ANGPTL4 varies with feeding to regulate LPL. In human serum, ANGPTL3/8 and ANGPTL4/8 complexes both increased postprandially, correlated negatively with HDL, and correlated positively with all other metabolic syndrome markers.

Definition of the Interaction Domain and Electron Transfer Route between Cytochrome c and Cytochrome Oxidase.

The reaction between cytochrome c () and cytochrome c oxidase (CcO) was studied using horse cytochrome c derivatives labeled with ruthenium trisbipyridine at Cys 39 (Ru-39-). Flash photolysis of a 1:1 complex between Ru-39- and bovine CcO at a low ionic strength resulted in the electron transfer from photoreduced heme c to Cu with an intracomplex rate constant of = 6 × 10 s. The K13A, K72A, K86A, and K87A Ru-39- mutants had nearly the same value but bound much more weakly to bovine CcO than wild-type Ru-39-, indicating that lysines 13, 72, 86, and 87 were involved in electrostatic binding to CcO, but were not involved in the electron transfer pathway.

Pharmacokinetics and Pharmacodynamics of LY2599666, a PEG-Linked Antigen Binding Fragment that Targets Soluble Monomer Amyloid-β.

LY2599666 is a humanized, affinity-optimized monoclonal antibody antigen-binding fragment linked to a PEG molecule and targets soluble amyloid-β (Aβ) monomers. This first-in-human dose ascending study assessed pharmacokinetics (PK) (measured as serum free LY2599666 concentration) and pharmacodynamic (PD) effects (measured as plasma total soluble Aβ40 and Aβ42) after a single subcutaneous (SC) dose of 10, 25, 100, and 200 mg LY2599666 in healthy subjects. As LY2599666 binds to multiple soluble Aβ monomers, a two-target mediated drug disposition model (TMDD) was developed to simultaneously fit serum LY2599666 concentration and Aβ monomer levels.

Circulating FGF21 proteolytic processing mediated by fibroblast activation protein.

Fibroblast growth factor 21 (FGF21), a hormone implicated in the regulation of glucose homoeostasis, insulin sensitivity, lipid metabolism and body weight, is considered to be a promising therapeutic target for the treatment of metabolic disorders. Despite observations that FGF21 is rapidly proteolysed in circulation rending it potentially inactive, little is known regarding mechanisms by which FGF21 protein levels are regulated. We systematically investigated human FGF21 protein processing using mass spectrometry.

Pyroglutamyl apelin-13 identified as the major apelin isoform in human plasma.

Apelin is emerging as an important hormone regulator of cardiovascular homoeostasis and an important biomarker for heart failure. Apelin concentrations have historically been measured by immunoassays; however, reported apelin concentrations measured in healthy volunteers show a large disparity from a few picograms per milliliter (pg/ml) to several nanograms per milliliter (ng/ml). Apelin exists in several isoforms ranging in size from 12 to 36 residues, and immunoassays generally cannot distinguish the specific forms present.

Proteomic analysis of demyelinated and remyelinating brain tissue following dietary cuprizone administration.

Cuprizone intoxication is a commonly used model of demyelination that allows the temporal separation of demyelination and remyelination. The underlying biochemical alterations leading to demyelination, using this model, remain unclear and may be multifold. Analysis of proteomic changes within the brains of cuprizone-exposed animals may help elucidate key cellular processes.

The Parkinson's disease kinase LRRK2 autophosphorylates its GTPase domain at multiple sites.

Mutations in leucine-rich repeat kinase 2 (LRRK2) are a common cause of inherited Parkinson's disease (PD). The protein is large and complex, but pathogenic mutations cluster in a region containing GTPase and kinase domains. LRRK2 can autophosphorylate in vitro within a dimer pair, although the significance of this reaction is unclear.

Characterization of metalloprotease cleavage products of human articular cartilage.

Objective: To identify, characterize, and compare proteolysis peptide products generated by metalloprotease digests of human articular cartilage.

Methods: Human articular cartilage was digested by the addition of exogenous metalloproteases, including matrix metalloproteinases 2, 3, 8, 9, 12, and 13 and aggrecanases ADAMTS-4 and ADAMTS-5. Proteolyzed peptide products were identified by proteomics methods using mass spectrometry.

Quantification of heart fatty acid binding protein as a biomarker for drug-induced cardiac and musculoskeletal necroses.

Heart fatty acid binding protein (Fabp3) is a cytosolic protein expressed primarily in heart, and to a lesser extent in skeletal muscle, brain, and kidney. During myocardial injury, the Fabp3 level in serum is elevated rapidly, making it an ideal early marker for myocardial infarction. In this study, an MS-based selected reaction monitoring method (LC-SRM) was developed for quantifying Fabp3 in rat serum.