GS-9L

ALKBH1 Slows Proliferation of Glioma Cell In Vitro but Worsens Survival In Vivo

Gliomas rely on translational plasticity for heterogeneity, stemness, and immune evasion; however, the regulatory mechanisms are not well understood. Nakayashiki et al. examined the function of tRNA dioxygenase ALKBH1 in glioma advancement.

Wobble modifications hm5C and f5C extend tRNA-Leu-CAA decoding from Leu-UUG to both Leu-UUG and Leu-UUA codons, potentially impacting translational mechanisms in glioma oncogenesis. To investigate the effects of ALKBH1-mediated wobble oxidation, they created ALKBH1 knockout (KO) and overexpression (OE) models in four glioma cell lines: rodent 9L/GS9L and human U87, U251, and A172 (Fig. 1a). Western blotting showed that the manipulation worked (Fig. 2b). The LC-MS/MS analysis of ALKBH1-associated tRNA modifications (hm5C, hm5Cm, f5C, f5Cm, m1A) demonstrated a consistent decrease in hm5C, hm5Cm, and f5Cm across all knockout lines, with the exception of U251 (Fig. 1c-d). It is important to note that f5C levels did not change after ALKBH1 KO, which suggests that unidentified dioxygenases may be involved. On the other hand, ALKBH1 OE raised hm5C and f5Cm levels in U87, 9L, and U251, but only in U251 did f5C levels go up a lot.

These variations suggest that ALKBH1 activity is dependent on the context, which could be due to differences in the availability of cofactors (like 2-oxoglutarate) or the way tRNA moves in different cells. In glioma cells, their data show that ALKBH1 mainly works as a tRNA wobble dioxygenase, changing m5C to hm5C and f5C at position 34. This is the biochemical basis for codon decoding and translational regulation.