Slc39a2-mediated Zinc Homeostasis Modulates Innate Immune Signaling in Phenylephrine-induced Cardiomyocyte Hypertrophy

Zinc dyshomeostasis has been involved in the pathogenesis of cardiac hypertrophy; however, the dynamic regulation of intracellular zinc and its downstream signaling in cardiac hypertrophy remain largely unknown. Here we screened ZIP (SLC39) family members that were responsible for zinc uptake in a phenylephrine (PE)-induced cardiomyocyte hypertrophy model. We found that Slc39a2 was the only member that was altered at mRNA level by PE treatment in neonatal rat ventricular myocytes (NRVMs), but its protein level was not affected. Zincpyr1 staining showed a significant decrease in zinc uptake after PE treatment or after Slc39a2 knockdown in NRVMs, indicating an inhibition of its transport activity during hypertrophy. Slc39a2 deficiency caused spontaneous hypertrophy in NRVMs, and further exacerbated the hypertrophic responses after PE treatment. RNA sequencing analysis confirmed a largely aggravated pro-hypertrophic transcriptome reprogramming after Slc39a2 knockdown. Interestingly, the innate immune pathways, including NOD signaling, TOLL-like receptor, NF?B, and IRFs, were substantially enriched after Slc39a2 knockdown. Whereas IRF7, the most sensitive among all IRFs, did not mediate the effect of Slc39a2 in hypertrophy, pro-hypertrophy phosphorylations of NF?B and STAT3 were significantly enhanced after Slc39a2 knockdown, in parallel with degradation of IkBa protein. Our data demonstrate that SLC39A2-mediated zinc homeostasis contributes to the remodeling of innate immune signaling in cardiomyocyte hypertrophy, and provide novel insights into the pathogenesis of heart failure and its treatment. Overall design: NRVMs were first transfected with siSlc39a2 or siNeg, then treated with PE for 36h after 12h of transfection. NRVMs were used to extracted RNA according to the manufacturer's instructions. Transcriptome sequencing of RNA was completed by Beijing Genomics Institution (BGI). Three independent biological replicate samples were sequenced for each group.