428 - Perinatal Nicotine Exposure Induces Dysregulation in the Lung Molecular Clock

Poster Number: 428
Publication Number: 428.429

Jie Liu, Lundquist Institute at Harbor-UCLA Medical Center, Torrance, CA, United States; Reiko Sakurai, The Lundquist Institute, Torrance, CA, United States; Ying Wang, The Lundquist Institute, Torrance, CA, United States; Tracy T. Dao, Lundquist Institute, Garden Grove, CA, United States; Leela Afrose, The Lundqusit Institute, Torrance, CA, United States; Tyler Rho, The Lundquist Institute for Biomedical Innovation, Irvine, CA, United States; Celia Yu, The Lundquist Institute at Harbor-UCLA Medical Center, Torrance, CA, United States; Virender K. Rehan, Harbor-UCLA Medical Center, Torrance, CA, United States; Dylan Hatai, The Lundquist Institute at UCLA-Harbor Medical Center, Torrance, CA, United States

Background: Dysregulated peripheral circadian rhythm is associated with enhanced inflammatory response and cellular senescence. Recent studies have demonstrated an association between exposure to cigarette smoke and dysregulated peripheral molecular clock in asthma patients. Although developmental smoke/nicotine exposure predisposes to asthma, its impact on the circadian clock is unknown. 

Objective: To determine whether developmental nicotine exposure alters the pulmonary molecular clock and whether this effect lasts well into adult life, leading to premature cellular senescence.

Design/Methods: Pair-fed pregnant Sprague-Dawley rats received once-daily 1mg/kg nicotine or saline diluent from embryonic day 6 (E6) to postnatal day 21 (PND21). Lungs from pups were collected on E21, PND21, or PND60 and flash-frozen for later mRNA and protein analysis. The expression of core clock genes (Bmal1, Clock, Cry1, Cry2, Per1, Per2, Reverba, Reverbb, Sirt1, and Rora) was determined by qRT-PCR on mRNA isolated from lungs. Protein levels of core clock proteins BMAL1, CLOCK, and REV-ERBα were determined using western analysis on proteins extracted from PND21 lungs. Western analysis was also conducted for cellular senescence markers p53 and p21 at PND60.

Results: Overall, the mRNA expression of core clock genes was significantly decreased (p < 0.05) in the nicotine treated group vs. the control group at E21 and PND21. Perinatal nicotine-induced downregulation of clock genes Bmal1 and Reverba was also confirmed by their down-regulated protein levels by western analysis at PND21. Interestingly, the expression of several down-regulated clock genes at E21 and PND21 in the nicotine-treated group was either not different or upregulated vs. the control group at PND60, suggesting a dynamic response of perinatal nicotine exposure on the peripheral molecular clock. However, senescence markers p53 and p21 were upregulated through PND60, implying premature cellular aging following perinatal nicotine exposure.Conclusion(s): Perinatal nicotine exposure leads to a dysregulated lung clock that lasts at least through adolescence, suggesting a novel mechanism underlying perinatal nicotine-induced lung damage and premature cellular senescence. Further studies are needed to determine the impact of perinatal nicotine exposure-induced dysregulated peripheral clock on lung health, gender specificity, and how long these effects last.
Grant Support: NIH (HL151769, HD127237, HD071731, and HL152915) and TRDRP (23RT-0018; 27IP0050; and T29IR0737).