Discovery of small molecules that normalize the transcriptome and enhance cysteine cathepsin activity in progranulin-deficient microglia.

Abstract

Patients with frontotemporal dementia (FTD) resulting from granulin (GRN) haploinsufficiency have reduced levels of progranulin and exhibit dysregulation in inflammatory and lysosomal networks. Microglia produce high levels of progranulin, and reduction of progranulin in microglia alone is sufficient to recapitulate inflammation, lysosomal dysfunction, and hyperproliferation in a cell-autonomous manner. Therefore, targeting microglial dysfunction caused by progranulin insufficiency represents a potential therapeutic strategy to manage neurodegeneration in FTD. Limitations of current progranulin-enhancing strategies necessitate the discovery of new targets. To identify compounds that can reverse microglial defects in Grn-deficient mouse microglia, we performed a compound screen coupled with high throughput sequencing to assess key transcriptional changes in inflammatory and lysosomal pathways. Positive hits from this initial screen were then further narrowed down based on their ability to rescue cathepsin activity, a critical biochemical readout of lysosomal capacity. The screen identified nor-binaltorphimine dihydrochloride (nor-BNI) and dibutyryl-cAMP, sodium salt (DB-cAMP) as two phenotypic modulators of progranulin deficiency. In addition, nor-BNI and DB-cAMP also rescued cell cycle abnormalities in progranulin-deficient cells. These data highlight the potential of a transcription-based platform for drug screening, and advance two novel lead compounds for FTD.

• Authors: Maria A Telpoukhovskaia, Kai Liu, Faten A Sayed, Jon Iker Etchegaray, Min Xie, Lihong Zhan, Yaqiao Li, Yungui Zhou, David Le, Ben A Bahr, Matthew Bogyo, Sheng Ding, Li Gan
• Journal: Scientific reports (Sci Rep) Vol. 10 Issue 1 Pg. 13688 (08 13 2020) ISSN: 2045-2322 [Electronic] England
• PMID: 32792571 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Grn protein, mouse
• Progranulins
• Small Molecule Libraries
• norbinaltorphimine
• Naltrexone
• Bucladesine
• Cysteine Proteases

Topics

• Animals
• Bucladesine (pharmacology)
• Cell Cycle (drug effects)
• Cells, Cultured
• Cysteine Proteases (metabolism)
• Disease Models, Animal
• Frontotemporal Dementia (drug therapy, genetics, metabolism)
• Gene Expression Profiling (methods)
• Gene Expression Regulation (drug effects)
• Gene Knockout Techniques
• High-Throughput Nucleotide Sequencing
• Humans
• Lysosomes (genetics, metabolism)
• Mice
• Microglia (cytology, drug effects, metabolism)
• Models, Biological
• Naltrexone (analogs & derivatives, pharmacology)
• Progranulins (deficiency)
• Sequence Analysis, RNA
• Small Molecule Libraries (pharmacology)