Exosomes in human semen carry a distinctive repertoire of small non-coding RNAs with potential regulatory functions.
Semen contains relatively ill-defined regulatory components that likely aid fertilization, but which could also interfere with defense against infection. Each ejaculate contains trillions of exosomes, membrane-enclosed subcellular microvesicles, which have immunosuppressive effects on cells important in the genital mucosa. Exosomes in general are believed to mediate inter-cellular communication, possibly by transferring small RNA molecules. We found that seminal exosome (SE) preparations contain a substantial amount of RNA from 20 to 100 nucleotides (nts) in length. We sequenced 20-40 and 40-100 nt fractions of SE RNA separately from six semen donors. We found various classes of small non-coding RNA, including microRNA (21.7% of the RNA in the 20-40 nt fraction) as well as abundant Y RNAs and tRNAs present in both fractions. Specific RNAs were consistently present in all donors. For example, 10 (of ∼2600 known) microRNAs constituted over 40% of mature microRNA in SE. Additionally, tRNA fragments were strongly enriched for 5'-ends of 18-19 or 30-34 nts in length; such tRNA fragments repress translation. Thus, SE could potentially deliver regulatory signals to the recipient mucosa via transfer of small RNA molecules.
Department of Obstetrics and Gynecology, University of Washington, Seattle, USA luciav@uw.edu.
Lucia
L
Vojtech
Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, USA.
Sangsoon
S
Woo
Department of Obstetrics and Gynecology, University of Washington, Seattle, USA.
Sean
S
Hughes
Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, USA.
Claire
C
Levy
Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, USA.
Lamar
L
Ballweber
Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, USA.
Renan P
RP
Sauteraud
Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, USA.
Johanna
J
Strobl
Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, USA.
Katharine
K
Westerberg
Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, USA Department of Medicine, University of Washington, Seattle, USA.
Raphael
R
Gottardo
Department of Medicine, University of Washington, Seattle, USA Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, USA.
Muneesh
M
Tewari
Department of Obstetrics and Gynecology, University of Washington, Seattle, USA Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, USA Department of Medicine, University of Washington, Seattle, USA luciav@uw.edu.
Florian
F
Hladik
D055354:Exosomes / Q000737:chemistry* / Q000648:ultrastructure; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D058727:RNA, Small Untranslated / Q000032:analysis* / Q000737:chemistry; D012343:RNA, Transfer / Q000032:analysis; D012661:Semen / Q000737:chemistry*
D035683:MicroRNAs; D012333:RNA, Messenger; D058727:RNA, Small Untranslated; D012343:RNA, Transfer