Codominant interference, antieffectors, and multitarget drugs

Impaired Redox Signaling in Huntington's Disease: Therapeutic Implications

Huntington's disease (HD) is a neurodegenerative disease triggered by expansion of polyglutamine repeats in the protein huntingtin. Mutant huntingtin (mHtt) aggregates and elicits toxicity by multiple mechanisms which range from dysregulated transcription to disturbances in several metabolic pathways in both the brain and peripheral tissues. Hallmarks of HD include elevated oxidative stress and imbalanced redox signaling. Disruption of antioxidant defense mechanisms, involving antioxidant molecules and enzymes involved in scavenging or reversing oxidative damage, have been linked to the pathophysiology of HD. In addition, mitochondrial function is compromised in HD leading to impaired bioenergetics and elevated production of free radicals in cells. However, the exact mechanisms linking redox imbalance to neurodegeneration are still elusive. This review will focus on the current understanding of aberrant redox homeostasis in HD and potential therapeutic interventions.

Novel opportunities for computational biology and sociology in drug discovery

Current drug discovery is impossible without sophisticated modeling and computation. In this review we outline previous advances in computational biology and, by tracing the steps involved in pharmaceutical development, explore a range of novel, high-value opportunities for computational innovation in modeling the biological process of disease and the social process of drug discovery. These opportunities include text mining for new drug leads, modeling molecular pathways and predicting the efficacy of drug cocktails, analyzing genetic overlap between diseases and predicting alternative drug use. Computation can also be used to model research teams and innovative regions and to estimate the value of academy-industry links for scientific and human benefit. Attention to these opportunities could promise punctuated advance and will complement the well-established computational work on which drug discovery currently relies.

Engineering small molecule specificity in nearly identical cellular environments

Methotrexate (MTX), an inhibitor of dihydrofolate reductase, was tethered to an FKBP12 ligand (SLF), and the resulting bifunctional molecule (MTXSLF) potently inhibits either enzyme but not both simultaneously. MTXSLF is cytotoxic to fibroblasts derived from FKBP12-null mice but is detoxified 40-fold by FKBP12 in wild-type fibroblasts. These studies demonstrate that non-target proteins in an otherwise identical genetic background can be used to predictably regulate the biological activity of synthetic molecules.

Amelioration of immune cell number depletion and potentiation of depressed detoxification system of tumor-bearing mice by curcumin

BACKGROUND

The true therapeutic benefit of the use of natural products, especially acceptable dietary components such as curcumin, which can spare the normal cells and boost host immunity, has opened new horizons in cancer prevention and treatment.

METHODS

In our model system we used Ehrlich's ascites carcinoma cells grown in peritoneal carity of Swiss albino mice and curcumin was fed every alternative day.

RESULTS

Here, we report that curcumin administration to tumor-bearing mice decreased tumor cell number significantly in a dose-dependent manner. Furthermore, tumor-induced depletion of immune cell number of the host, as was evidenced from the decrease in bone marrow progenitor as well as thymic and splenic mononuclear cell numbers, was reintrated by curcumin. In fact, curcumin inhibited tumor-induced apoptosis of both thymocytes and splenocytes thereby restoring immune cell numbers to normal level in treated Ehrlich's ascites carcinoma-bearing mice. Moreover, curcumin was not toxic to the host; rather in tumor-bearing mice it inhibited hematopoietic toxicity, acted as a hepatoprotective agent and activated depressed anti-oxidant and detoxification systems.

CONCLUSION

The ability of curcumin to regress tumor as well as to protect the host from tumor-induced immunosuppression and toxicity strongly supports the candidacy of curcumin as a potential agent for the dietary therapy of cancer.

Ubiquitin fusion technique and related methods

The ubiquitin fusion technique, developed in 1986, is still the method of choice for producing a desired N-terminal residue in a protein of interest in vivo. This technique is also used as a tool for protein expression. Over the past two decades, several otherwise unrelated methods were invented that have in common the use of ubiquitin fusions as a component of design. I describe the original ubiquitin fusion technique, its current applications, and other methods that use the properties of ubiquitin fusions.

A bifunctional molecule that displays context-dependent cellular activity

The cell-permeable dihydrofolate reductase inhibitor methotrexate was covalently linked to a ligand for the protein FKBP to create a bifunctional molecule called MTXSLF. The covalent tether between the two ligands was designed to be prohibitively short, so that unfavorable protein-protein interactions between DHFR and FKBP preclude formation of a trimeric complex. In vitro and in vivo experiments demonstrate that MTXSLF is an effective inhibitor of human DHFR, but that efficacy is decreased in the presence of human FKBP due to the high concentration of FKBP and its tight affinity for MTXSLF. MTXSLF also inhibits Plasmodium falciparum DHFR in vitro, but a low concentration of the weaker binding Plasmodium FKBP has no effect on the inhibitory potency of MTXSLF in vivo. These studies illustrate a potentially general strategy for modulating the biological activity of synthetic molecules that depends on the ligand-binding properties of a nontarget protein.