Retinoic acid signalling induces the differentiation of mouse fetal liver-derived hepatic progenitor cells.
BACKGROUND
Hepatic progenitor cells (HPCs) can be isolated from fetal liver and extrahepatic tissues. Retinoic acid (RA) signalling plays an important role in development, although the role of RA signalling in liver-specific progenitors is poorly understood.


OBJECTIVE
We sought to determine the role of RA in regulating hepatic differentiation.


METHODS
RNA was isolated from liver tissues of various developmental stages. Liver marker expression was assessed by reverse transcriptase-polymerase chain reaction and immunofluorescence staining. Reversibly immortalized HPCs derived from mouse embryonic day 14.5 (E14.5) liver (aka, HP14.5) were established. Albumin promoter-driven reporter (Alb-GLuc) was used to monitor hepatic differentiation. Glycogen synthesis was assayed as a marker for terminal hepatic differentiation.


RESULTS
Retinoic acid receptor (RAR)-alpha, retinoid X receptor (RXR)-alpha and RXR-gamma expressed in E12.5 to postnatal day 28 liver samples. Expression of RAR-beta and RXR-beta was low perinatally, whereas RAR-gamma was undetectable in prenatal tissues and increased postnatally. Retinal dehydrogenase 1 and 2 (Raldh1 and Raldh2) were expressed in all tissues, while Raldh3 was weakly expressed in prenatal samples but was readily detected postnatally. Nuclear receptor corepressors were highly expressed in all tissues, while expression of nuclear co-activators decreased in perinatal tissues and increased after birth. HP14.5 cells expressed high levels of early liver stem cell markers. Expression of RA signalling components and coregulators was readily detected in HP14.5. RA was shown to induce Alb-GLuc activity and late hepatocyte markers. RA was further shown to induce glycogen synthesis in HP14.5 cells, an important function of mature hepatocytes.


CONCLUSIONS
Our results strongly suggest that RA signalling may play an important role in regulating hepatic differentiation.
Huang
Jiayi
J
Key Laboratory of Diagnostic Medicine designated by the Ministry of Education of China, The Affiliated Hospitals of Chongqing Medical University, Chongqing, China.
Bi
Yang
Y
Zhu
Gao-Hui
GH
He
Yun
Y
Su
Yuxi
Y
He
Bai-Cheng
BC
Wang
Yi
Y
Kang
Quan
Q
Chen
Liang
L
Zuo
Guo-Wei
GW
Luo
Qing
Q
Shi
Qiong
Q
Zhang
Bing-Qiang
BQ
Huang
Ailong
A
Zhou
Lan
L
Feng
Tao
T
Luu
Hue H
HH
Haydon
Rex C
RC
He
Tong-Chuan
TC
Tang
Ni
N
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D008099:Liver / Q000166:cytology / Q000196:embryology*; D051379:Mice; D056971:Nuclear Receptor Co-Repressor 1 / Q000032:analysis; D056920:Nuclear Receptor Coactivator 1 / Q000032:analysis; D018168:Receptors, Retinoic Acid / Q000032:analysis / Q000235:genetics; D047488:Retinoid X Receptors / Q000032:analysis / Q000235:genetics; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology*; D014212:Tretinoin / Q000494:pharmacology*
C539128:Ncor1 protein, mouse; D056971:Nuclear Receptor Co-Repressor 1; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014212:Tretinoin; C538861:Ncoa1 protein, mouse; D056920:Nuclear Receptor Coactivator 1