Date

Thursday 09 Jul 2026

Time

15:15 - 15:45

Location

BW006

Supervisor

Marco van Eijk

2nd reviewer

Sander van Kasteren

Jury

Sebastian Geibel

Lysosomes play a central role in degradation and cellular homeostasis, and their dysfunction has been shown to contribute to the pathogenesis of Lysosomal Storage Diseases (LSDs) including Gaucher’s disease, atherosclerosis, and obesity. Lysosomal membrane protein Glycoprotein Non-Metastatic Protein B (GPNMB) is heavily upregulated in macrophagic storage cells in LSDs and therefore is a promising marker for LSDs. In addition to upregulation of GPNMB, lysosomal stress leads to the inactivation of mTORC1, which results in dephosphorylation and nuclear translocation of transcription factor TFEB. This study investigates if GPNMB is upregulated and MiT/TFE family member TFE3 translocates to the nucleus in the THP-1 leukemia cell line during maturation. Therefore, THP-1 is maturated to macrophagic cells with PMA. Subsequently to these background THP-1 maturation experiments, the effect of lysosomal stressors HEPES, Chloroquine, Bafilomycin A, and Torin1 on TFE3 nuclear translocation in THP-1 is studied. Western blotting and GPNMB quantification demonstrated the upregulation of GPNMB in PMA maturated THP-1 with a maximum value around 24h. Moreover, this study showed that nuclear translocation of MiT/TFE family member TFE3 takes place in maturated THP-1 with a peak value around 6h-16h. Since the cytosolic marker actin showed presence in the nuclear fractions, the effect of HEPES, Chloroquine, Bafilomycin A, and Torin1 on TFE3 localisation needs further investigation and the nuclear fractionation method of THP-1 with NP-40 requires optimization.