David W. Kuo

Adipose Fibroblast Growth Factor 21 Is Up-Regulated by Peroxisome Proliferator-Activated Receptor γ and Altered Metabolic States

Adipose tissue is a metabolically responsive endocrine organ that secretes a myriad of adipokines. Antidiabetic drugs such as peroxisome proliferator-activated receptor (PPAR) γ agonists target adipose tissue gene expression and correct hyperglycemia via whole-body insulin sensitization. The mechanism by which altered gene expression in adipose tissue affects liver and muscle insulin sensitivity (and thus glucose homeostasis) is not fully understood. One possible mechanism involves the alteration in adipokine secretion, in particular the up-regulation of secreted factors that increase whole-body insulin sensitivity. Here, we report the use of transcriptional profiling to identify genes encoding for secreted proteins the expression of which is regulated by PPARγ agonists. Of the 379 genes robustly regulated by two structurally distinct PPARγ agonists in the epididymal white adipose tissue (EWAT) of db/db mice, 33 encoded for known secreted proteins, one of which was FGF21. Although FGF21 was recently reported to be up-regulated in cultured adipocytes by PPARγ agonists and in liver by PPARα agonists and induction of ketotic states, we demonstrate that the protein is transcriptionally up-regulated in adipose tissue in vivo by PPARγ agonist treatment and under a variety of physiological conditions, including fasting and high fat diet feeding. In addition, we found that circulating levels of FGF21 protein were increased upon treatment with PPARγ agonists and under ketogenic states. These results suggest a role for FGF21 in mediating the antidiabetic activities of PPARγ agonists.

Phosphinic acid inhibitors of matrix metalloproteinases

Abstract The matrix metalloproteinase stromelysin-1 (MMP-3) is inhibited more strongly by peptidyl phosphinic acid 7 than by its corresponding phosphonamidate and phosphonate analogs. Extending a benzyl group at P′ 1 to a phenylethyl group in 8 further increases the potency (K i = 1.4 nM). Enhanced potency with an extended substituent into the P 3 region was observed.

Inhibition of stromelysin-1 (MMP-3) by peptidyl phosphinic acids

Abstract A series of phosphinic acid-containing peptide inhibitors of human stromelysin-1 (MMP-3) were prepared. The P1 through P3 subsites were varied in a systematic manner on analogs possessing an invariant P1′-P3′ segment. The in vitro activity of these compounds as inhibitors of stromelysin and collagenase is discussed.

SYNTHESIS OF NEW THIAZINOINDOLE DERIVATIVES AND THEIR EVALUATION AS INHIBITORS OF HUMAN LEUKOCYTE ELASTASE AND OTHER RELATED SERINE PROTEASES

A novel thiazinoindole tricyclic ring system was designed as potential inhibitors of serine proteases. The compounds were synthesized by ring closure at 80–90°C in poliphosphoric acid of the appropriate N′-alkyl or aryl substituted indolylthiourea derivatives. Members of this class of compounds inhibited human leukocyte elastase (Ki=30–40 μM) and α-chymotrypsin.

Inactivation of Human Fibroblast Collagenase by Chloroacetyl N-Hydroxypeptide Derivatives

When human fibroblast collagenase was incubated with ClCH2CO-(N-OH)Leu-Ala-Gly-NH2 (2-5 mM) in Tris buffer, pH 7.4 at 25 degrees C, a slow, time-dependent inhibition of the enzyme was observed. Dialysis against a buffer to remove free inhibitor did not reactivate the enzyme. A reversible competitive inhibitor, phthaloyl-GlyP-Ile-Trp-NHBzl (50 microM) partially protected the enzyme from inactivation by the compound. From the concentration dependent rates of inactivation Ki = 0.5 +/- 0.1 mM and k3, the rate constant for inactivation = 3.4 +/- 0.3 x 10(-3) min-1 were determined. The inactivation followed the pH optimum (6.5-7.0) for the enzyme activity, suggesting direct involvement of the same active site residue(s). The reaction mode of the inhibitor may be analogous to that of the inactivation of Pseudomonas aeruginosa elastase [Nishino, N. and Powers, J. (1980) J. Biol. Chem., 255, 3482] in which the catalytic glutamate carboxyl was alkylated by the inhibitor after its binding to enzyme through the hydroxamic Zn2+ ligand. All carboxyl groups in the inactivated collagenase were modified with 0.1 M ethyl dimethylaminopropyl carbodiimide/0.5 M glycinamide in 4 M guanidine at pH 5. The inactivator-affected carboxyl group was then regenerated with 1 M imidazole at pH 8.9, 37 degrees C for 12 h and the protein was radiolabeled with 3H-glycine methyl ester and carbodiimide to incorporate 0.9 residue glycine per mol enzyme.