Nicotine Induced Murine Spermatozoa Apoptosis via Up-Regulation of Deubiquitinated RIP1 by Trim27 Promoter Hypomethylation

Biol Reprod. 2016 Feb;94(2):31. doi: 10.1095/biolreprod.115.131656. Epub 2015 Nov 25.

Abstract

Nicotine significantly promoted apoptosis in stages I, VII, VIII, and XI spermatogonia, stages I, VII, VIII, X, and XI spermatocytes, and stages I-V, VII, and VIII elongating spermatids. To explore the underlying molecular mechanisms, sperm mRNA next-generation sequencing of nicotine-treated mice was conducted. Out of the 86 genes related to apoptosis, Tnf (tumor necrosis factor alpha) was screened to be the most significant varied transcript, and the Onto-pathway analysis indicated that the TNF apoptotic pathway was especially activated by nicotine exposure. The TNF pathway was further studied at the gene and protein levels. The results showed that RIP1, the key component in the TNF apoptotic pathway, was up-expressed in its deubiquitinated form in nicotine-treated mice testis. TRIM27, an E3 ubiquitin ligase that activated TNF apoptotic pathway through up-regulating deubiquitinated RIP1, was also overexpressed in nicotine-treated spermatocytes; moreover, four consecutive CpG sites near the Trim27 transcription start site were less frequently methylated. Finally, in vitro experiments of Trim27 overexpression and RNA interference in GC-1 spermatogonial cells confirmed that the RIP1 deubiquitination and TRIM27 hyopmethylation were both positively correlated with spermatocyte apoptosis. In summary, our study suggests that nicotine may induce murine spermatozoal apoptosis via the TNF apoptotic pathway through up-regulation of deubiquitinated RIP1 by Trim27 promoter hypomethylation.

Keywords: RIP1 deubiquitination; Trim27 hypomethylation; apoptosis; nicotine; spermatozoa.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • DNA Methylation / drug effects*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • GTPase-Activating Proteins / genetics
  • GTPase-Activating Proteins / metabolism*
  • Male
  • Mice
  • Nicotine / pharmacology*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Promoter Regions, Genetic / drug effects
  • Signal Transduction / drug effects
  • Spermatozoa / drug effects*
  • Spermatozoa / metabolism
  • Testis / drug effects
  • Testis / metabolism
  • Ubiquitin-Protein Ligases
  • Up-Regulation / drug effects*

Substances

  • DNA-Binding Proteins
  • GTPase-Activating Proteins
  • Nuclear Proteins
  • Ralbp1 protein, mouse
  • Nicotine
  • Trim27 protein, mouse
  • Ubiquitin-Protein Ligases