The expression profile of Claudin family members in the developing mouse lung and expression alterations resulting from exposure to secondhand smoke (SHS)

ABSTRACT

Claudins are tight junctional proteins implicated in cell polarity and epithelial barrier maintenance. Claudin misregulation adversely impacts developmental aspects of cell differentiation and proliferation. The current research evaluated transcriptional expression for Claudins 1–11 and 18 in the developing murine lung at embryonic days (E) 14.5, 16.5, and 18.5 and at post-natal day (PN) 3 and PN15. Mouse lungs were also assessed by immunohistochemical analysis to qualitatively evaluate Claudin protein expression. Pregnant dams were further exposed to secondhand smoke (SHS) from embryonic day (E)15.5 to 18.5 and Claudin mRNA was immediately screened in pup lungs. Other than Claudin-6, mRNA expression patterns for Claudin family members tended to decrease at E16.5, increase at E18.5, and decrease again at PN3 before reaching a peak of expression at PN15. Claudin-6 mRNA expression decreased through gestation and into post-natal periods. Immunohistochemical profiling implicated a subset of Claudins as plausible orchestrators of proximal vs. distal lung barrier establishment. Assessment of Claudin mRNA expression at E18.5 following SHS exposure revealed a significant reduction in transcription for all Claudins except Claudin-18 (no change). These data support the need for further studies using gene targeted mice that knock-in/out specific Claudins so that precise functions in the normal and diseased lung can be determined.

KEYWORDS:

• Claudin
• lung
• tobacco

Declaration of interests

The authors declare that they have no financial or non-financial conflicts of interest.

Additional information

Funding

This work was supported by a grant from the Flight Attendant's Medical Research Institute (FAMRI, PRR and JAA) and a BYU Mentoring Environment Grant (PRR and JAA).

Notes on contributors

Joshua B. Lewis

JBL and FRJ assisted in experimental design, maintained animals, and performed surgeries. JBL and BJM conduced the qPCR experiments and JBL and BK performed the immunohistochemistry. PRR and JAA conceived of the study and supervised in its implementation, interpretation, and writing. All authors assisted in manuscript preparation and approved of the final submitted version.

Felix R. Jimenez

JBL and FRJ assisted in experimental design, maintained animals, and performed surgeries. JBL and BJM conduced the qPCR experiments and JBL and BK performed the immunohistochemistry. PRR and JAA conceived of the study and supervised in its implementation, interpretation, and writing. All authors assisted in manuscript preparation and approved of the final submitted version.

Brigham J. Merrell

JBL and FRJ assisted in experimental design, maintained animals, and performed surgeries. JBL and BJM conduced the qPCR experiments and JBL and BK performed the immunohistochemistry. PRR and JAA conceived of the study and supervised in its implementation, interpretation, and writing. All authors assisted in manuscript preparation and approved of the final submitted version.

Brent Kimbler

JBL and FRJ assisted in experimental design, maintained animals, and performed surgeries. JBL and BJM conduced the qPCR experiments and JBL and BK performed the immunohistochemistry. PRR and JAA conceived of the study and supervised in its implementation, interpretation, and writing. All authors assisted in manuscript preparation and approved of the final submitted version.

Juan A. Arroyo

JBL and FRJ assisted in experimental design, maintained animals, and performed surgeries. JBL and BJM conduced the qPCR experiments and JBL and BK performed the immunohistochemistry. PRR and JAA conceived of the study and supervised in its implementation, interpretation, and writing. All authors assisted in manuscript preparation and approved of the final submitted version.

Paul R. Reynolds

JBL and FRJ assisted in experimental design, maintained animals, and performed surgeries. JBL and BJM conduced the qPCR experiments and JBL and BK performed the immunohistochemistry. PRR and JAA conceived of the study and supervised in its implementation, interpretation, and writing. All authors assisted in manuscript preparation and approved of the final submitted version.