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LIM Domain Only 2 Regulates Endothelial Proliferation, Angiogenesis, and Tissue Regeneration

View Article: PubMed Central - PubMed

ABSTRACT

Background: LIM domain only 2 (LMO2, human gene) is a key transcription factor that regulates hematopoiesis and vascular development. However, its role in adult endothelial function has been incompletely characterized.

Methods and results: In vitro loss‐ and gain‐of‐function studies on LMO2 were performed in human umbilical vein endothelial cells with lentiviral overexpression or short hairpin RNA knockdown (KD) of LMO2, respectively. LMO2 KD significantly impaired endothelial proliferation. LMO2 controls endothelial G1/S transition through transcriptional regulation of cyclin‐dependent kinase 2 and 4 as determined by reverse transcription polymerase chain reaction (PCR), western blot, and chromatin immunoprecipitation, and also influences the expression of Cyclin D1 and Cyclin A1. LMO2 KD also impaired angiogenesis by reducing transforming growth factor‐β (TGF‐β) expression, whereas supplementation of exogenous TGF‐β restored defective network formation in LMO2 KD human umbilical vein endothelial cells. In a zebrafish model of caudal fin regeneration, RT‐PCR revealed that the lmo2 (zebrafish gene) gene was upregulated at day 5 postresection. The KD of lmo2 by vivo‐morpholino injections in adult Tg(fli1:egfp)y1 zebrafish reduced 5‐bromo‐2′‐deoxyuridine incorporation in endothelial cells, impaired neoangiogenesis in the resected caudal fin, and substantially delayed fin regeneration.

Conclusions: The transcriptional factor LMO2 regulates endothelial proliferation and angiogenesis in vitro. Furthermore, LMO2 is required for angiogenesis and tissue healing in vivo. Thus, LMO2 is a critical determinant of vascular and tissue regeneration.

No MeSH data available.


LMO2 overexpression promoted endothelial G1/S transition. A, Cell cycle analysis by propidium iodide (PI) staining. B, Quantification of cell fractions in G1, S, and G2/M phases. C, mRNA level of G1/S‐related genes. D, Western blot examination of G1/S‐related genes. Data are presented as mean±SEM (n=3). *P<0.05 vs control (CT).
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jah31811-fig-0003: LMO2 overexpression promoted endothelial G1/S transition. A, Cell cycle analysis by propidium iodide (PI) staining. B, Quantification of cell fractions in G1, S, and G2/M phases. C, mRNA level of G1/S‐related genes. D, Western blot examination of G1/S‐related genes. Data are presented as mean±SEM (n=3). *P<0.05 vs control (CT).

Mentions: Cell cycle analysis showed that the fraction of cells in S phase were increased (14.7% versus 7.9% CT) and that in G1 phase decreased in LMO2 OE condition (Figure 3A and 3B). However, cell proliferation was not changed by LMO2 OE (Figure S2). Following LMO2 OE, Cyclin D1 mRNA level was increased, whereas CDK2 and CDK4 mRNA levels remained stable (Figure 3C). Interestingly, LMO2 OE increased only Cyclin D1 and Cyclin A1 protein levels but not that of CDK2, CDK4, Cyclin E, or p21 (Figure 3D).


LIM Domain Only 2 Regulates Endothelial Proliferation, Angiogenesis, and Tissue Regeneration
LMO2 overexpression promoted endothelial G1/S transition. A, Cell cycle analysis by propidium iodide (PI) staining. B, Quantification of cell fractions in G1, S, and G2/M phases. C, mRNA level of G1/S‐related genes. D, Western blot examination of G1/S‐related genes. Data are presented as mean±SEM (n=3). *P<0.05 vs control (CT).
© Copyright Policy - creativeCommonsBy-nc
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5121509&req=5

jah31811-fig-0003: LMO2 overexpression promoted endothelial G1/S transition. A, Cell cycle analysis by propidium iodide (PI) staining. B, Quantification of cell fractions in G1, S, and G2/M phases. C, mRNA level of G1/S‐related genes. D, Western blot examination of G1/S‐related genes. Data are presented as mean±SEM (n=3). *P<0.05 vs control (CT).
Mentions: Cell cycle analysis showed that the fraction of cells in S phase were increased (14.7% versus 7.9% CT) and that in G1 phase decreased in LMO2 OE condition (Figure 3A and 3B). However, cell proliferation was not changed by LMO2 OE (Figure S2). Following LMO2 OE, Cyclin D1 mRNA level was increased, whereas CDK2 and CDK4 mRNA levels remained stable (Figure 3C). Interestingly, LMO2 OE increased only Cyclin D1 and Cyclin A1 protein levels but not that of CDK2, CDK4, Cyclin E, or p21 (Figure 3D).

View Article: PubMed Central - PubMed

ABSTRACT

Background: LIM domain only 2 (LMO2, human gene) is a key transcription factor that regulates hematopoiesis and vascular development. However, its role in adult endothelial function has been incompletely characterized.

Methods and results: In vitro loss&#8208; and gain&#8208;of&#8208;function studies on LMO2 were performed in human umbilical vein endothelial cells with lentiviral overexpression or short hairpin RNA knockdown (KD) of LMO2, respectively. LMO2 KD significantly impaired endothelial proliferation. LMO2 controls endothelial G1/S transition through transcriptional regulation of cyclin&#8208;dependent kinase 2 and 4 as determined by reverse transcription polymerase chain reaction (PCR), western blot, and chromatin immunoprecipitation, and also influences the expression of Cyclin D1 and Cyclin A1. LMO2 KD also impaired angiogenesis by reducing transforming growth factor&#8208;&beta; (TGF&#8208;&beta;) expression, whereas supplementation of exogenous TGF&#8208;&beta; restored defective network formation in LMO2 KD human umbilical vein endothelial cells. In a zebrafish model of caudal fin regeneration, RT&#8208;PCR revealed that the lmo2 (zebrafish gene) gene was upregulated at day 5 postresection. The KD of lmo2 by vivo&#8208;morpholino injections in adult Tg(fli1:egfp)y1 zebrafish reduced 5&#8208;bromo&#8208;2&prime;&#8208;deoxyuridine incorporation in endothelial cells, impaired neoangiogenesis in the resected caudal fin, and substantially delayed fin regeneration.

Conclusions: The transcriptional factor LMO2 regulates endothelial proliferation and angiogenesis in&nbsp;vitro. Furthermore, LMO2 is&nbsp;required for angiogenesis and tissue healing in&nbsp;vivo. Thus, LMO2 is a critical determinant of vascular and tissue regeneration.

No MeSH data available.