Telomerase reverse transcriptase promotes angiogenesis in neonatal rats after hypoxic-ischemic brain damage

PeerJ. 2022 Oct 21:10:e14220. doi: 10.7717/peerj.14220. eCollection 2022.

Abstract

Background: Angiogenesis is an endogenous repair mechanism following hypoxic-ischemic brain damage (HIBD). Interestingly, recent studies have shown that angiogenesis can be regulated by telomerase reverse transcriptase (TERT), a critical component of telomerase. As telomerase reverse transcriptase can promote angiogenesis after stroke, we hypothesized that it could also promote angiogenesis after HIBD. To test this hypothesis, we developed in vivo and in vitro HIBD models in neonatal rats.

Methods: TERT was overexpressed by lentivirus and adenovirus infection, and levels were measured using quantitative real-time polymerase chain reaction. We used a cell counting kit to quantify the proliferation rate of brain microvascular endothelial cells (BMECs), and immunofluorescence staining to measure CD34 expression levels. A microvessel formation assay was used to evaluate angiogenesis. Blood-brain barrier (BBB) integrity was assessed using immunohistochemical staining for ZO-1 and Evans Blue staining. Lastly, the expression level of Notch-1 was measured by western blotting.

Results: Overexpression of TERT promoted the proliferation of BMECs after hypoxic-ischemic damage in vitro. TERT overexpression increased the formation of microvessels in the neonatal brain after HIBD both in vivo and in vitro. Overexpression of TERT improved BBB integrity in the brains of neonatal rats after HIBD. In addition, the expression level of Notch-1 was increased in BMECs following oxygen glucose deprivation, and overexpression of TERT further increased Notch-1 expression levels in BMECs following oxygen glucose deprivation.

Discussion: Our results reveal that telomerase reverse transcriptase promotes angiogenesis and maintains the integrity of the blood-brain barrier after neonatal hypoxic-ischemic brain damage. Furthermore, the Notch-1 signaling pathway appears to contribute to the angiogenic function of telomerase reverse transcriptase. This protective effect of telomerase reverse transcriptase opens new horizons for future investigations aimed at uncovering the full potential of telomerase reverse transcriptase as a promising new target for the treatment of hypoxic-ischemic encephalopathy.

Keywords: Angiogenesis; Blood-brain barrier; Hypoxic ischemic brain damage; Neonate; Telomerase reverse transcriptase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Brain / metabolism
  • Endothelial Cells / metabolism
  • Glucose / metabolism
  • Hypoxia-Ischemia, Brain* / metabolism
  • Oxygen / metabolism
  • Rats
  • Telomerase* / genetics

Substances

  • Telomerase
  • Oxygen
  • Glucose

Grants and funding

Jiao Li received support from the National Natural Science Foundation of China (grant #81501302). Zhi Fang received support from The Grant from the Science and Technology Bureau of Sichuan Province (grant #2021YFS0247; #2022YFS0360) and the Foundation of Health and Family Planning Commission of Sichuan Province (CN) (grant #17ZD028). The New Bud foundation of West China Second University Hospital, Sichuan University provided support through grant #Kx105, to Jiao Li and grant #Kx097, to Haiting Liu. The National Natural Science Foundation of China contributed to the design of the study (grant #81501302, to Jiao Li). The Foundation of Health and Family Planning Commission of Sichuan Province (CN) (grant #17ZD028, to Zhi Fang) and the New Bud foundation of West China Second University Hospital, Sichuan University (grant #Kx105, to Jiao Li; grant #Kx097, to Haiting Liu), contributed to the collection, analysis and interpretation of data, the writing of the report, and the decision to submit the article for publication.