Discovery of Enzymatic Targets of Transcriptional Activators via in Vivo Covalent Chemical Capture.

The network of activator protein-protein interactions (PPIs) that underpin transcription initiation is poorly defined, particularly in the cellular context. The transient nature of these contacts and the often low abundance of the participants present significant experimental hurdles. Through the coupling of in vivo covalent chemical capture and shotgun LC-MS/MS (MuDPIT) analysis, we can trap the PPIs of transcriptional activators in a cellular setting and identify the binding partners in an unbiased fashion.

Sequence context and crosslinking mechanism affect the efficiency of in vivo capture of a protein-protein interaction.

Protein-protein interactions (PPIs) are essential for implementing cellular processes and thus methods for the discovery and study of PPIs are highly desirable. An emerging method for capturing PPIs in their native cellular environment is in vivo covalent chemical capture, a method that uses nonsense suppression to site specifically incorporate photoactivable unnatural amino acids (UAAs) in living cells. However, in one study we found that this method did not capture a PPI for which there was abundant functional evidence, a complex formed between the transcriptional activator Gal4 and its repressor protein Gal80.

TOC1: characterization of a selective oligomeric tau antibody.

The work presented herein addresses a specific portion of the tau pathology, pre-fibrillar oligomers, now thought to be important pathological components in Alzheimer's disease and other neurodegenerative tauopathies. In previous work, we generated an antibody against purified recombinant cross-linked tau dimers, called Tau Oligomeric Complex 1 (TOC1). TOC1 recognizes tau oligomers and its immunoreactivity is elevated in Alzheimer's disease brains.

Tau oligomers and tau toxicity in neurodegenerative disease.

AD (Alzheimer's disease) is a progressive neurodegenerative disorder characterized by the extracellular accumulation of amyloid β-peptide and the intracellular accumulation of tau. Although there is much evidence linking tau to neurodegeneration, the precise mechanism of tau-mediated neurotoxicity remains elusive. The presence of tau-positive pre-tangle neurons lacking neurofibrillary tangles has been reported in AD brain tissue.

Tau as a therapeutic target in neurodegenerative disease.

Tau is a microtubule-associated protein thought to help modulate the stability of neuronal microtubules. In tauopathies, including Alzheimer's disease and several frontotemporal dementias, tau is abnormally modified and misfolded resulting in its disassociation from microtubules and the generation of pathological lesions characteristic for each disease. A recent surge in the population of people with neurodegenerative tauopathies has highlighted the immense need for disease-modifying therapies for these conditions, and new attention has focused on tau as a potential target for intervention.