A current review of the literature reveals a continued reliance on the synthesis of novel structures with increased potency, rather than a focus on maintaining optimal physicochemical properties associated with ADMET throughout drug optimization. Particular attention to the optimum region of lipophilicity, as well as monitoring of lipophilic efficiency indices, may contribute significantly to the overall quality of candidate drugs at different stages of discovery.

Trodusquemine (MSI-1436) causes rapid and reversible weight loss in genetic models of obesity. To better predict the potential effects of trodusquemine in the clinic, we investigated the effects of trodusquemine treatment in a murine model of diet-induced obesity (DIO). Trodusquemine suppressed appetite, reduced body weight (BW) in a fat-specific manner, and improved plasma insulin and leptin levels in mice. Screening assays revealed that trodusquemine selectively inhibited protein-tyrosine phosphatase 1B (PTP1B), a key enzyme regulating insulin and leptin signaling. Trodusquemine significantly enhanced insulin-stimulated tyrosine phosphorylation of insulin receptor (IR) β and STAT3, direct targets of PTP1B, in HepG2 cells in vitro and/or hypothalamic tissue in vivo. These data establish trodusquemine as an effective central and peripheral PTP1B inhibitor with the potential to elicit noncachectic fat-specific weight loss and improve insulin and leptin levels.

The recent discovery of at least 23 enzymes that mediate palmitoylation (palmitoyl acyltransferases or PATs 1 ) suggests that regulation of palmitoylation is far more complex than previously assumed. Defining PAT-substrate specificities in living vertebrate systems is a critical next step in understanding the complexity of regulated palmitoylation and the potential consequences of malfunctioning PATs on downstream signaling events. To date, five PAT genes have been implicated in human diseases ranging from schizophrenia to cancer and Huntington disease, so defining the substrates of individual PATs will provide important clues linking these known mutations to an associated disease. One reason why our understanding of palmitoylation has not kept pace with that of other post-translational protein modifications has been the lack of rapid and sensitive methods to study this phenomenon. Recent advances in the field have provided tools that can identify palmitoylated proteins and match known palmitoyl proteins to PATs already suspected of mediating their palmitoylation (1-3). But until now, there has been no method to identify substrates of specific PATs in a living vertebrate system without prior knowledge of a possible relationship between PAT and substrate. Palmitoyl-cysteine isolation capture and analysis (PICA) 2 solves this problem. In this study, we used PICA and HeLa (human cervical carcinoma cells) to identify CKAP4/p63 as a physiologically important substrate of DHHC2, a PAT that has been linked to the metastatic potential of liver and colon cancer (4).The ability of PICA to identify PAT substrates is based on the principle that it quantifies the differential frequency of palmitoylation of individual proteins in control conditions versus conditions in which the function of a single PAT is reduced by siRNA-mediated gene knockdown (Fig. 1). The process to identify substrates of DHHC2 consisted of four basic steps. In the first part we generated two distinct pools of palmitoylated proteins in HeLa cells: one from untreated, control HeLa cells and the other from HeLa cells in which the activity of one PAT, DHHC2, was reduced. These two distinct pools of palmitoylated proteins were then captured, and the differences in the degree of palmitoylation of individual proteins among the two pools were identified. To do this, first we reduced the expression of ZDHHC2 mRNA (and consequently the function of the encoded enzyme, DHHC2) in HeLa cells using siRNA-mediated gene knockdown, resulting in a reduced level of palmitoylation of DHHC2 substrates. Total protein from knockdown and control cells was prepared by first blocking all free (including non-palmitoylated) thiols with methyl methanethiosulfonate (MMTS). This was followed by selective exposure of all

Selective estrogen receptor modulators (SERMs) are a diverse group of nonsteroidal compounds that function as agonists or antagonists for estrogen receptors (ERs) in a target gene-specific and tissue-specific fashion. SERM specificity involves tissue-specific expression of ER subtypes, differential expression of co-regulatory proteins in various tissues, and varying ER conformational changes induced by ligand binding. To date, the major clinical applications of SERMs are their use in the prevention and treatment of breast cancer, the prevention of osteoporosis, and the maintenance of beneficial serum lipid profiles in postmenopausal women. However, SERMs have also been found to promote adverse effects, including thromboembolic events and, in some cases, carcinogenesis, that have proven to be obstacles in their clinical utility. In this review, we discuss the mechanisms of SERM tissue specificity and highlight the therapeutic application of well-known and emergent SERMs.