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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 gene expression increased following caudal fin resection and the regeneration process. A, To analyze changes in gene expression in the regenerating caudal fin, the amputated tissues from 15 fish were collected at day 0 (left panel) and regenerating distal tissues were resected and collected at 1, 2, or 5 days after the original resection (n=5 for each time point) (right panel, a fin at 2 days postresection). B, Gene expression of lmo2 in the regenerating fin. C, Gene expression of tie2 in the regenerating fin. Data are presented as mean±SEM (n=5). *P<0.05 vs control.
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jah31811-fig-0005: lmo2 gene expression increased following caudal fin resection and the regeneration process. A, To analyze changes in gene expression in the regenerating caudal fin, the amputated tissues from 15 fish were collected at day 0 (left panel) and regenerating distal tissues were resected and collected at 1, 2, or 5 days after the original resection (n=5 for each time point) (right panel, a fin at 2 days postresection). B, Gene expression of lmo2 in the regenerating fin. C, Gene expression of tie2 in the regenerating fin. Data are presented as mean±SEM (n=5). *P<0.05 vs control.

Mentions: To test whether lmo2 is required for tissue regeneration, we assessed the gene expression of lmo2 and another early endothelial marker gene tie2 in caudal fin tissue at 0, 1, 2, and 5 days after caudal fin resection (Figure 5A). We observed that tie2 gene expression remained stable (Figure 5C) from day 0 to day 5 (at which time about 50% of the caudal fin was regenerated). Conversely, lmo2 gene expression level significantly increased by 50% at day 5 when about 50% of the caudal fin was regenerated (Figure 5B).


LIM Domain Only 2 Regulates Endothelial Proliferation, Angiogenesis, and Tissue Regeneration
lmo2 gene expression increased following caudal fin resection and the regeneration process. A, To analyze changes in gene expression in the regenerating caudal fin, the amputated tissues from 15 fish were collected at day 0 (left panel) and regenerating distal tissues were resected and collected at 1, 2, or 5 days after the original resection (n=5 for each time point) (right panel, a fin at 2 days postresection). B, Gene expression of lmo2 in the regenerating fin. C, Gene expression of tie2 in the regenerating fin. Data are presented as mean±SEM (n=5). *P<0.05 vs control.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5121509&req=5

jah31811-fig-0005: lmo2 gene expression increased following caudal fin resection and the regeneration process. A, To analyze changes in gene expression in the regenerating caudal fin, the amputated tissues from 15 fish were collected at day 0 (left panel) and regenerating distal tissues were resected and collected at 1, 2, or 5 days after the original resection (n=5 for each time point) (right panel, a fin at 2 days postresection). B, Gene expression of lmo2 in the regenerating fin. C, Gene expression of tie2 in the regenerating fin. Data are presented as mean±SEM (n=5). *P<0.05 vs control.
Mentions: To test whether lmo2 is required for tissue regeneration, we assessed the gene expression of lmo2 and another early endothelial marker gene tie2 in caudal fin tissue at 0, 1, 2, and 5 days after caudal fin resection (Figure 5A). We observed that tie2 gene expression remained stable (Figure 5C) from day 0 to day 5 (at which time about 50% of the caudal fin was regenerated). Conversely, lmo2 gene expression level significantly increased by 50% at day 5 when about 50% of the caudal fin was regenerated (Figure 5B).

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.