Deoxyhypusine Synthase Promotes a Pro-Inflammatory Macrophage Phenotype

Obesity is characterized by adipose tissue expansion, macrophage infiltration, and the development of chronic low-grade meta-inflammation that drives insulin resistance and metabolic dysfunction. Eukaryotic translation initiation factor 5A (eIF5A) is the only protein known to be uniquely post-translationally modified and activated by deoxyhypusine synthase (DHPS) to generate a hypusine (Hyp) residue. Activated eIF5A controls the translation of a subset of mRNAs that play a role in inflammation, but a role for the DHPS/eIF5AHyp axis in obesity-associated adipose tissue inflammation has not been tested. We found DHPS/eIF5AHyp levels to be increased in the stromal vascular fraction of adipose tissue from mice fed a high fat diet and in murine macrophages activated to a proinflammatory M1 phenotype. DHPS deficiency in M1 macrophages decreased global mRNA translation and protein synthesis of key inflammatory mediators, IL-1β and MIP-1α. Transcriptomes of LPS+IFN-γ-stimulated DHPS-deficient macrophages revealed reduced characteristics of an M1 signature and a phenotypic switch consistent with characteristics of an anti-inflammatory M2 signature. In support of these observations, macrophage migration in a zebrafish tailfin injury model was reduced with chemical inhibition of DHPS, and DHPS deficiency in myeloid cells of HFD-fed mice inhibited M1 macrophage accumulation in adipose tissue and improved glucose tolerance. Together, these findings indicate that DHPS is required for the translation of a subset of mRNAs required for inflammation and chemotaxis in macrophages and may contribute to a proinflammatory M1-like phenotype. Purified total RNA was first evaluated for its quantity, and quality, using Agilent Bioanalyzer 2100. All RNA samples had a RIN (RNA Integrity Number) of eight or higher. Each library was quantified, and its quality accessed by Qubit and Agilent Bioanalyzer, and multiple libraries were pooled in equal molarity. Average size of library insert was approximately 110b. Pooled libraries were applied to Ion Sphere Particles (ISP) with template preparation and amplification using Ion OneTouch 2, followed by ISP loading onto a PI chip and sequencing on Ion Proton semiconductor (Life Technologies). A Phred quality score (Q score) was used to measure the quality of sequencing. More than 90% of the sequencing reads reached Q30 (99.9% base call accuracy).