Abstract
The alveolar epithelium consists of squamous alveolar type (AT) I and cuboidal ATII cells. ATI cells cover 95-98% of the alveolar surface, thereby playing a critical role in barrier integrity, and are extremely thin, thus permitting efficient gas exchange. During lung injury, ATI cells die, resulting in increased epithelial permeability. ATII cells re-epithelialize the alveolar surface via proliferation and transdifferentiation into ATI cells. Transdifferentiation is characterized by down-regulation of ATII cell markers, upregulation of ATI cell markers, and cell spreading, resulting in a change in morphology from cuboidal to squamous, thus restoring normal alveolar architecture and function. The mechanisms underlying ATII to ATI cell transdifferentiation have not been well studied in vivo. A prerequisite for mechanistic investigation is a rigorous, unbiased method to quantitate this process. Here, we used SPCCreERT2;mTmG mice, in which ATII cells and their progeny express green fluorescent protein (GFP), and applied stereologic techniques to measure transdifferentiation during repair after injury induced by LPS. Transdifferentiation was quantitated as the percent of alveolar surface area covered by ATII-derived (GFP1) cells expressing ATI, but not ATII, cell markers. Using this methodology, the time course and magnitude of transdifferentiation during repair was determined. We found that ATI cell loss and epithelial permeability occurred by Day 4, and ATII to ATI cell transdifferentiation began by Day 7 and continued until Day 16. Notably, transdifferentiation and barrier restoration are temporally correlated. This methodology can be applied to investigate the molecular mechanisms underlying transdifferentiation, ultimately revealing novel therapeutic targets to accelerate repair after lung injury.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 519-526 |
| Number of pages | 8 |
| Journal | American Journal of Respiratory Cell and Molecular Biology |
| Volume | 57 |
| Issue number | 5 |
| DOIs | |
| State | Published - Nov 1 2017 |
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Keywords
- Alveolar epithelium
- Lung injury and repair
- Transdifferentiation
ASJC Scopus subject areas
- Molecular Biology
- Pulmonary and Respiratory Medicine
- Clinical Biochemistry
- Cell Biology
Cite this
Unbiased quantitation of alveolar type II to alveolar type i cell transdifferentiation during repair after lung injury in mice. / Jansing, Nicole L.; McClendon, Jazalle; Henson, Peter M.; Tuder, Rubin M.; Hyde, Dallas M.; Zemans, Rachel L.
In: American Journal of Respiratory Cell and Molecular Biology, Vol. 57, No. 5, 01.11.2017, p. 519-526.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Unbiased quantitation of alveolar type II to alveolar type i cell transdifferentiation during repair after lung injury in mice
AU - Jansing, Nicole L.
AU - McClendon, Jazalle
AU - Henson, Peter M.
AU - Tuder, Rubin M.
AU - Hyde, Dallas M.
AU - Zemans, Rachel L.
PY - 2017/11/1
Y1 - 2017/11/1
N2 - The alveolar epithelium consists of squamous alveolar type (AT) I and cuboidal ATII cells. ATI cells cover 95-98% of the alveolar surface, thereby playing a critical role in barrier integrity, and are extremely thin, thus permitting efficient gas exchange. During lung injury, ATI cells die, resulting in increased epithelial permeability. ATII cells re-epithelialize the alveolar surface via proliferation and transdifferentiation into ATI cells. Transdifferentiation is characterized by down-regulation of ATII cell markers, upregulation of ATI cell markers, and cell spreading, resulting in a change in morphology from cuboidal to squamous, thus restoring normal alveolar architecture and function. The mechanisms underlying ATII to ATI cell transdifferentiation have not been well studied in vivo. A prerequisite for mechanistic investigation is a rigorous, unbiased method to quantitate this process. Here, we used SPCCreERT2;mTmG mice, in which ATII cells and their progeny express green fluorescent protein (GFP), and applied stereologic techniques to measure transdifferentiation during repair after injury induced by LPS. Transdifferentiation was quantitated as the percent of alveolar surface area covered by ATII-derived (GFP1) cells expressing ATI, but not ATII, cell markers. Using this methodology, the time course and magnitude of transdifferentiation during repair was determined. We found that ATI cell loss and epithelial permeability occurred by Day 4, and ATII to ATI cell transdifferentiation began by Day 7 and continued until Day 16. Notably, transdifferentiation and barrier restoration are temporally correlated. This methodology can be applied to investigate the molecular mechanisms underlying transdifferentiation, ultimately revealing novel therapeutic targets to accelerate repair after lung injury.
AB - The alveolar epithelium consists of squamous alveolar type (AT) I and cuboidal ATII cells. ATI cells cover 95-98% of the alveolar surface, thereby playing a critical role in barrier integrity, and are extremely thin, thus permitting efficient gas exchange. During lung injury, ATI cells die, resulting in increased epithelial permeability. ATII cells re-epithelialize the alveolar surface via proliferation and transdifferentiation into ATI cells. Transdifferentiation is characterized by down-regulation of ATII cell markers, upregulation of ATI cell markers, and cell spreading, resulting in a change in morphology from cuboidal to squamous, thus restoring normal alveolar architecture and function. The mechanisms underlying ATII to ATI cell transdifferentiation have not been well studied in vivo. A prerequisite for mechanistic investigation is a rigorous, unbiased method to quantitate this process. Here, we used SPCCreERT2;mTmG mice, in which ATII cells and their progeny express green fluorescent protein (GFP), and applied stereologic techniques to measure transdifferentiation during repair after injury induced by LPS. Transdifferentiation was quantitated as the percent of alveolar surface area covered by ATII-derived (GFP1) cells expressing ATI, but not ATII, cell markers. Using this methodology, the time course and magnitude of transdifferentiation during repair was determined. We found that ATI cell loss and epithelial permeability occurred by Day 4, and ATII to ATI cell transdifferentiation began by Day 7 and continued until Day 16. Notably, transdifferentiation and barrier restoration are temporally correlated. This methodology can be applied to investigate the molecular mechanisms underlying transdifferentiation, ultimately revealing novel therapeutic targets to accelerate repair after lung injury.
KW - Alveolar epithelium
KW - Lung injury and repair
KW - Transdifferentiation
UR - http://www.scopus.com/inward/record.url?scp=85032722205&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85032722205&partnerID=8YFLogxK
U2 - 10.1165/rcmb.2017-0037MA
DO - 10.1165/rcmb.2017-0037MA
M3 - Article
C2 - 28586241
AN - SCOPUS:85032722205
VL - 57
SP - 519
EP - 526
JO - American Journal of Respiratory Cell and Molecular Biology
JF - American Journal of Respiratory Cell and Molecular Biology
SN - 1044-1549
IS - 5
ER -