PT  - JOURNAL ARTICLE
AU  - Jimi L. Rosenkrantz
AU  - Michael Martinez
AU  - Adithi Mahankali
AU  - Lucia Carbone
AU  - Shawn L. Chavez
TI  - Investigation of Human Endogenous Retrovirus-K (ERVK) Expression and Function in Normal Placentation and Preterm Pregnancy
AID  - 10.1101/2021.11.22.469425
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.11.22.469425
4099  - http://biorxiv.org/content/early/2021/11/22/2021.11.22.469425.short
4100  - http://biorxiv.org/content/early/2021/11/22/2021.11.22.469425.full
AB  - Background There is a growing body of evidence indicating the importance of endogenous retrovirus (ERV) derived proteins during early development and reproduction in mammals. Recently, a protein derived from the youngest ERV in humans, ERVK (HML2), was shown to be expressed during human placentation. Since a number of highly similar ERVK proviral loci exist across the human genome, locus-specific analysis of ERVK transcription and identification of the coding sequence expressed in the human placenta is difficult. Thus, despite its activity in early human development, the native expression and function of ERVK in the human placenta remains largely uncharacterized.Results In this study, we comprehensively examined locus-specific ERVK transcription across several human placental tissues and cell types. Through a combination of RNA-seq and siRNA knock-down analyses, we identified the expression of a single ERVK locus, ERVK11q23.3, as (1) being significantly upregulated in preterm compared to term placenta, (2) predominantly expressed by mononuclear trophoblasts, (3) capable of encoding a truncated viral-like envelope protein, and (4) contributing to the expression cytokines involved in both antiviral and anti-inflammatory innate immune responses in human placental trophoblasts and BeWo choriocarcinoma cells, respectively.Conclusions Collectively, the results of this study highlight the utility of studying locus-specific ERVK expression, provide a thorough characterization of locus-specific ERVK transcription from human placental tissues, and indicate that altered expression of placental ERVK11q23.3 influences interferon antiviral response, which may contribute to preterm birth and other pregnancy complications.Competing Interest StatementThe authors have declared no competing interest.