Fig. 5. DB008 and talazoparib treatment rescue nutrient starvation-induced loss of soluble PARP16. (A) Amino acid (aa) and serum starvation decreases PARP16 levels which is prevented by DB008 treatment. HAP1 WT and HAP1 PARP16 KO cells were incubated in complete media (IMDM + 10% FBS) or starvation media (1× Hanks' balanced salt solution, HBSS) in the presence or absence of 100 nM DB008 for 16 h, then dosed with 5 μg ml⁻¹ puromycin for 5 minutes to capture the state of translation, followed by western blotting. (B) In contrast to inhibition of PARP16, neither inhibition of the proteasome nor lysosome prevent aa starvation-mediated decreases in PARP16 levels. HAP1 WT cells were incubated in complete media or starvation media (1× HBSS) in the presence of 300 nM DB008, 10 μM MG132 (proteosome inhibitor), or the lysosomal inhibitors bafilomycin A1 (Baf-A1; 1 μM), or chloroquine (CLQ; 50 μM) for 16 h, followed by western blotting. (C) aa and serum starvation leads to a loss of soluble PARP16, which is rescued by the PARP16 inhibitors, DB008 and talazoparib (Tal). HAP1 WT cells were incubated in complete media or starvation media and dosed with either DB008 or Tal for 16 h, followed by western blotting. Cells were lysed in RIPA buffer and after clarification, western blotting was performed on the RIPA-soluble fraction (supernatant) and RIPA-insoluble fraction (pellet).