Patient-Derived Induced Pluripotent Stem Cell Models for Phenotypic Screening in the Neuronal Ceroid Lipofuscinoses.

Batten disease or neuronal ceroid lipofuscinosis (NCL) is a group of rare, fatal, inherited neurodegenerative lysosomal storage disorders. Numerous genes (CLN1-CLN8, CLN10-CLN14) were identified in which mutations can lead to NCL; however, the underlying pathophysiology remains elusive. Despite this, the NCLs share some of the same features and symptoms but vary in respect to severity and onset of symptoms by age. Some common symptoms include the progressive loss of vision, mental and motor deterioration, epileptic seizures, premature death, and in the rare adult-onset, dementia. Currently, all forms of NCL are fatal, and no curative treatments are available. Induced pluripotent stem cells (iPSCs) can differentiate into any cell type of the human body. Cells reprogrammed from a patient have the advantage of acquiring disease pathogenesis along with recapitulation of disease-associated phenotypes. They serve as practical model systems to shed new light on disease mechanisms and provide a phenotypic screening platform to enable drug discovery. Herein, we provide an overview of available iPSC models for a number of different NCLs. More specifically, we highlight findings in these models that may spur target identification and drug development.

Passage Variation of PC12 Cells Results in Inconsistent Susceptibility to Externally Induced Apoptosis.

The PC12 cell line is a widely used in vitro model for screening the neuroprotective activity of small molecule libraries. External insult due to serum deprivation or addition of etoposide induces cell death by apoptosis. While this screening method is commonly used in early stage drug discovery no protocol accounting for cell passage number effect on neuroprotective activity has been disclosed. We herein report that passage variation results in false-positive/false-negative identification of neuroprotective compounds; undifferentiated PC12 cells with high passage number are less sensitive to injury induced by serum-deprivation or etoposide treatment. In contrast, NGF differentiated PC12 cells of later passage number are more sensitive to injury induced by etoposide than lower passage number but only after 72 h. Passage number also affects the adherence phenotype of the PC12 cells, complicating screening assays. We report an optimized protocol for screening the neuroprotective activity of small molecules in PC12 cells, which accounts for passage number variations.

Proteasome activation is a mechanism for pyrazolone small molecules displaying therapeutic potential in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a progressive and ultimately fatal neurodegenerative disease. Pyrazolone containing small molecules have shown significant disease attenuating efficacy in cellular and murine models of ALS. Pyrazolone based affinity probes were synthesized to identify high affinity binding partners and ascertain a potential biological mode of action. Probes were confirmed to be neuroprotective in PC12-SOD1(G93A) cells. PC12-SOD1(G93A) cell lysates were used for protein pull-down, affinity purification, and subsequent proteomic analysis using LC-MS/MS. Proteomics identified the 26S proteasome regulatory subunit 4 (PSMC1), 26S proteasome regulatory subunit 6B (PSMC4), and T-complex protein 1 (TCP-1) as putative protein targets. Coincubation with appropriate competitors confirmed the authenticity of the proteomics results. Activation of the proteasome by pyrazolones was demonstrated in the absence of exogenous proteasome inhibitor and by restoration of cellular protein degradation of a fluorogenic proteasome substrate in PC12-SOD1(G93A) cells. Importantly, supplementary studies indicated that these molecules do not induce a heat shock response. We propose that pyrazolones represent a rare class of molecules that enhance proteasomal activation in the absence of a heat shock response and may have therapeutic potential in ALS.

Phenylboronic-acid-based carbohydrate binders as antiviral therapeutics: monophenylboronic acids.

BACKGROUND: The development of carbohydrate-binding agents as novel therapeutics for the inhibition of highly glycosylated enveloped viruses has generated much attention in recent literature. Possessing a potential dual mode of action by inhibiting virus entry and exposing the virion to neutralization by the host immune system upon the deletion of envelope glycans under drug pressure, these substances might provide a new direction in antiviral treatment. Phenylboronic acids are widely known to bind the cis-diol functionality of carbohydrate structures, thereby identifying themselves as potential lead structures. To date, few details have been disclosed of the structure-activity relationship of these substances in correlation to their antiviral activity. METHODS: In this study, a compound library of a diverse range of ortho-, meta- and para- ring-substituted monophenylboronic acids and glutamine phenylboronic acid analogues was prepared, characterized and evaluated to probe antiviral activity versus a broad range of (enveloped) viruses. RESULTS: The compounds described herein lack antiviral activity. They also did not show measurable binding to HIV type-1 (HIV-1) gp120, using surface plasmon resonance technology. However, of note is the general lack of toxicity, which suggests that further investigation of the compounds as potential therapeutics is needed. CONCLUSIONS: The monophenylboronic acids tested exhibited no antiviral activity as potential carbohydrate binders versus a broad range of enveloped and non-enveloped viruses. The compounds tested did not bind HIV-1 gp120, possibly because of their small size and lack of multivalency.