Direct and indirect regulation of β-glucocerebrosidase by the transcription factorsUSF2andONECUT2

Abstract

AbstractMutations in theGBAgene, which encodes the lysosomal enzyme β-glucocerebrosidase (GCase), are the most prevalent genetic susceptibility factor for Parkinson’s disease (PD). However, only approximately 20% of carriers develop the disease, suggesting the presence of genetic modifiers influencing the risk of developing PD in the presence ofGBAmutations. Here we screened 1,634 human transcription factors (TFs) for their effect on GCase activity in cell lysates of the human glioblastoma line LN-229, into which we introduced the pathogenicGBAL444P variant via adenine base editing. Using a novel arrayed CRISPR activation library, we uncovered 11 TFs as regulators of GCase activity. Among these, activation ofMITFandTFECincreased lysosomal GCase activity in live cells, while activation ofONECUT2andUSF2decreased it. Conversely, ablating USF2 increasedGBAmRNA and led to enhanced levels of GCase protein and activity. While MITF, TFEC, and USF2 affectedGBAtranscription, ONECUT2 was found to control GCase trafficking by modulating the guanine exchange factors PLEKHG4 and PLEKHG4B. Hence, our study provides a systematic approach to identifying modulators of GCase activity, expands the transcriptional landscape ofGBAregulation, and deepens our understanding of the mechanisms involved in influencing GCase activity.