Korean Red ginseng-induced astrocytic HIF-1α: A key regulator of neuroglobin derived from neural stem cell differentiation in physiologic retina and brain

• Published in: Journal of ginseng research 2024-12
• Main Authors: Moon, Sunhong, Park, Jinseo, Kim, Sueun, Kim, Minsu, Jeon, Hui Su, Kim, Hyungsu, Kim, Young-Myeong, Kim, Ji-Yoon, Choi, Yoon Kyung
• Format: Article
• Language: English
• Subjects: astrocytes; hypoxia-inducible factor 1 alpha; Korean Red ginseng; neural stem cell; neuroglobin
• ISSN: 1226-8453
• DOI: 10.1016/j.jgr.2024.12.008

Neuroglobin (Ngb) and growth-associated protein (GAP) 43 in neurons are associated with axonal regeneration. Korean Red ginseng extract (KRGE) enhances glial fibrillary acidic protein (GFAP)-positive astrocytes and hypoxia-inducible factor-1α (HIF-1α) protein activation in normoxic astrocytes. However, crosstalk between neural stem cell (NSC) differentiation and astrocytic HIF-1α in the KRGE-treated normoxic brain and retina remains unclear. We investigated whether KRGE-treated astrocytic HIF-1α can enhance NSC differentiation and increase the mature neurons expressing Ngb and GAP43. Mature neuronal markers such as neuronal nuclei (NeuN) or microtubule-associated protein 2 (MAP2) were tested with Ngb in the mouse brain or retinal tissues post-KRGE administration. Direct KRGE treatment of NSCs or astrocytes was evaluated for Ngb levels. The KRGE-treated astrocyte conditioned media (ACM) were transferred to NSCs and HIF-1α levels were reduced using small interfering RNA transfection (si-HIF-1α) in astrocytes. si-HIF-1α-ACM with KRGE was tested for NSC differentiation. KRGE-administered mice showed significantly enhanced co-expression of Ngb with NeuN in the brain and MAP2 in the retina, along with the NSC marker Nestin, than water-administered mice. The KRGE treatment did not increase Ngb levels in NSCs, but stimulated astrocytes to secrete factors affecting NSCs’ differentiate into mature neurons and astrocytes. The KRGE-treated mouse retinas showed GFAP- and HIF-1α double-positive cells. Co-treatment with si-HIF-1α-transfected KRGE–ACM blocked KRGE–ACM-induced NSC differentiation into astrocytes or Ngb-expressing neurons. KRGE stimulates astrocytic HIF-1α, which regulates NSC differentiation into mature neurons expressing Ngb, thereby promoting regeneration by enhancing NSC–astrocyte crosstalk in the physiological retina and brain. [Display omitted]