McCartney Morgan E, Wheeler Gavin M, O'Neill Audrey G, Patel Jeet H, Litt Zoey R, Calise S John, Kollman Justin M, Wills Andrea E
Department of Biochemistry. University of Washington, Seattle WA.
Program in Biological Physics, Structure, and Design. University of Washington, Seattle WA.
bioRxiv. 2024 Aug 21:2024.07.29.605679. doi: 10.1101/2024.07.29.605679.
Regeneration of lost tissue requires biosynthesis of metabolites needed for cell proliferation and growth. Among these are the critical purine nucleotides ATP and GTP. The abundance and balance of these purines is regulated by inosine monophosphate dehydrogenase 2 (IMPDH2), which catalyzes the committing step of GTP synthesis. IMPDH2 assembles into filaments that resist allosteric inhibition under conditions of high GTP demand. Here we asked whether IMPDH2 is required in the highly proliferative context of regeneration, and whether its assembly into filaments takes place in regenerating tissue. We find that inhibition of IMPDH2 leads to impaired tail regeneration and reduced cell proliferation in the tadpole . We find that both endogenous and fluorescent fusions of IMPDH2 robustly assemble into filaments throughout the tadpole tail, and that the regenerating tail creates a sensitized condition for filament formation. These findings clarify the role of purine biosynthesis in regeneration and reveal that IMPDH2 enzyme filament formation is a biologically relevant mechanism of regulation in vertebrate regeneration.
丢失组织的再生需要生物合成细胞增殖和生长所需的代谢物。其中包括关键的嘌呤核苷酸ATP和GTP。这些嘌呤的丰度和平衡由肌苷单磷酸脱氢酶2（IMPDH2）调节，该酶催化GTP合成的关键步骤。IMPDH2组装成细丝，在高GTP需求条件下抵抗变构抑制。在这里，我们询问IMPDH2在再生的高增殖环境中是否是必需的，以及它组装成细丝是否发生在再生组织中。我们发现抑制IMPDH2会导致蝌蚪尾巴再生受损和细胞增殖减少。我们发现IMPDH2的内源性和荧光融合物在整个蝌蚪尾巴中都能强烈组装成细丝，并且再生尾巴为细丝形成创造了一个敏感条件。这些发现阐明了嘌呤生物合成在再生中的作用，并揭示了IMPDH2酶细丝形成是脊椎动物再生中一种生物学上相关的调节机制。
