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Barrett, T.

Publications and source records attributed to Barrett, T..

4 recordsLinked to original sources

Contrasting Sequence with Structure: Pre-training Graph Representations with PLMs

Understanding protein function is vital for drug discovery, disease diagnosis, and protein engineering. While Protein Language Models (PLMs) pre-trained on vast protein sequence datasets have achieved remarkable success, equivalent Protein Structure Models (PSMs) remain underrepresented. We attribute this to the relative lack of high-confidence structural data and suitable pre-training objectives. In this context, we introduce BioCLIP, a contrastive learning framework that pre-trains PSMs by leveraging PLMs, generating meaningful per-residue and per-chain structural representations. When evaluated on tasks such as protein-protein interaction, Gene Ontology annotation, and Enzyme Commission number prediction, BioCLIP-trained PSMs consistently outperform models trained from scratch and further enhance performance when merged with sequence embeddings. Notably, BioCLIP approaches, or exceeds, specialized methods across all benchmarks using its singular pre-trained design. Our work addresses the challenges of obtaining quality structural data and designing self-supervised objectives, setting the stage for more comprehensive models of protein function. Source code is publicly available2.

bioinformatics↗

Hepatic JNK-mediated bile acid homeostasis regulates liver cancer through PPARα

cJun NH2-terminal kinase (JNK) inhibition has been suggested as a potential treatment for insulin resistance and steatosis through activation of the transcription factor PPAR. However, the long-term consequences have not been evaluated. We found that hepatic JNK deficiency alters bile acid and cholesterol metabolism, resulting in hepatic expression of FGF15 and activation of ERK in cholangiocytes, which ultimately promotes their proliferation. Genetic inactivation of PPAR identifies PPAR hyperactivation as the molecular mechanism for these deleterious effects. Our analysis indicates that hepatic PPAR activation is oncogenic: PPAR deficiency protects mice against carcinogen-induced hepatocellular carcinoma under high fat diet (HFD) condition. These surprising results urge the re-consideration of using JNK inhibitors or PPAR agonists for the treatment of metabolic syndrome.

cancer biology↗

LRRK2 kinase inhibitors induce a reversible effect in the lungs of non-human primates with no measurable pulmonary deficits

Putative gain-of-function mutations in leucine-rich repeat kinase 2 (LRRK2), resulting in increased kinase activity and cellular toxicity, are a leading genetic cause of Parkinsons disease (PD). Hence, there is strong interest in developing LRRK2 kinase inhibitors as a disease-modifying therapy. Published reports that repeat dosing with two LRRK2 kinase inhibitors (GNE-7915 and GNE-0877) induce histopathological changes in the lung of non-human primates Fuji et al. 2015 (1) raised concerns about potential safety liability of LRRK2 kinase inhibitors. In the present study, we sought to determine whether previously observed effects in the lung: (a) represent on-target pharmacology, but with the potential for margin of safety, (b) are reversible upon drug withdrawal, and (c) are associated with pulmonary function deficits. To this end, we evaluated the histopathological effects, toxicokinetics and target inhibition of three structurally diverse LRRK2 kinase inhibitors, GNE-7915 (30 mg/kg, BID, as a positive control), MLi-2 (15 and 50 mg/kg, QD) and PFE-360 (3 and 6 mg/kg, QD) following 2 weeks of dosing in non-human primates. Subsets of animals dosed with GNE-7915 or MLi-2 were evaluated after 2-week dose-free periods. All three LRRK2 kinase inhibitors induced mild cytoplasmic vacuolation of type II pneumocytes, as reported previously, confirming an on-target effect of these compounds. Interestingly, despite lower doses of both PFE-360 and MLi-2 producing nearly complete inhibition of LRRK2 kinase activity in the brain as assessed by levels of pS935-LRRK2, histopathological changes in lung were absent in animals treated with low-dose PFE-360 and observed only sporadically in the low-dose MLi-2 group. The lung effect was fully reversible at 2 weeks post-dosing of GNE-7915. In a second study of identical dosing with MLi-2 and GNE-7915, no deficits were observed in a battery of translational pulmonary functional tests. In aggregate, these results do not preclude the development of LRRK2 kinase inhibitors for clinical investigation in Parkinsons disease.

pharmacology and toxicology↗

Dynamic control of proinflammatory cytokines Il-1β and Tnf-α by macrophages is necessary for functional spinal cord regeneration in zebrafish

Spinal cord injury leads to a massive response of innate immune cells (microglia, macrophages, neutrophils) both, in non-regenerating mammals and in successfully regenerating zebrafish, but the role of these immune cells in functional spinal cord regeneration in zebrafish has not been addressed. Here we show that inhibiting inflammation reduces and promoting it accelerates axonal regeneration in larval zebrafish. Mutant analyses show that peripheral macrophages, but not neutrophils or microglia, are necessary and sufficient for full regeneration. Macrophage-less irf8 mutants show prolonged inflammation with elevated levels of Il-1{beta} and Tnf-. Decreasing Il-1{beta} levels or number of Il-1{beta}+ neutrophils rescues functional regeneration in irf8 mutants. However, during early regeneration, interference with Il-1{beta} function impairs regeneration in irf8 and wildtype animals. Inhibiting Tnf- does not rescue axonal growth in irf8 mutants, but impairs it in wildtype animals, indicating a pro-regenerative role of Tnf-. Hence, inflammation is tightly and dynamically controlled by macrophages to promote functional spinal cord regeneration in zebrafish.

developmental biology↗