211 - Perinatal Nicotine Exposure-Induced Cardiac Phenotype is Mediated by MIAT/miR-1 Axis and is Transmitted Transgenerationally

Poster Number: 211
Publication Number: 211.203

Virender K. Rehan, Harbor-UCLA, Torrance, CA, United States; TSAI-DER CHUANG, The lundquist Institute at UCLA medical center, torrance, CA, United States; Celia Yu, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States; Reiko Sakurai, The Lundquist Institute of Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States; Jie Liu, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States; Omid Khorram, Department of Obstetrics and Gynecology David Geffen School of Medicine at UCLA Chief, Division of Reproductive Endocrinology and Infertility Harbor-UCLA Medical Center, Torrance, CA, United States

Background: Increased predisposition to cardiac fibrosis in perinatally nicotine exposed heart has been shown, but the underlying mechanisms remain unclear. Moreover, whether this phenotype is also transmitted transgenerationally as has been shown for the lung is also not known. MIAT, a long non-coding RNA, has been implicated in cardiac injury, and miR-1 is known to target fibronectin (FN1) and fibulin 2 (FBLN2). We hypothesized that perinatal nicotine exposure altered the MIAT/miR-1/FN1/FBLN2 axis and is transmitted transgenerationally.

Objective:

To study miR-1 and MIAT expression, as well as the expression of extracellular matrix proteins involved in cardiac injury and fibrosis, in the hearts of rat pups from the first- and the third-generation offspring exposed to nicotine in F0 gestation.

Design/Methods: Pregnant Sprague-Dawley rat dams received either nicotine (1 mg/kg once daily sc) or placebo from embryonic day 6 to postnatal day (PND) 21. Following delivery at term, the F1 pups were breastfed ad lib and hearts from some of the pups were collected at PND21. Some F1 male and female littermates served as breeders to generate F2 offspring, but without subsequent exposure to nicotine in the F1 or F2 pregnancies. F3 pups were similarly obtained, using F2 offspring as breeders, and hearts from F3 pups were collected at PND21. F1 and F3 hearts were examined for MIAT, miR-1, FN1 and FBLN2 expression by qRT-PCR, western blotting and immunohistochemistry. The luciferase reporter assay and RNA immunoprecipitation were used for confirmation of predicted target genes of miR-1 and the interaction between miR-1 and MIAT.

 

Results: Perinatal nicotine exposure resulted in increased expression of FN1 and FBLN2 at PND21 in F1 and F3 hearts, accompanied by a decrease in miR-1 and an increase in MIAT expressions. FBLN2 and FN1 were confirmed as direct targets of miR-1 and MIAT was demonstrated to act as a sponge for miR-1. Gain-of function of miR-1 decreased the expression of FN1 and FBLN2. In contrast, MIAT knockdown resulted in miR-1 induction, with a decrease in FN1 and FBLN2 expression in cardiac fibroblasts. Nicotine treatment of cultured neonatal primary rat cardiac fibroblasts increased MIAT levels, while suppressing the miR-1 expression.

Conclusion(s):

Perinatal nicotine exposure induced cardiac phenotype is transmitted transgenerationally and mediated via MIAT/miR-1 axis. These data provide a novel mechanistic basis for increased cardiac extracellular matrix deposition following perinatal nicotine exposure and for the first time demonstrates the transgenerational transmission of perinatal nicotine-induced cardiac phenotype.