Overexpression and Knockdown of Hypoxia-Inducible Factor 1 Disrupt the Expression of Steroidogenic Enzyme Genes and Early Embryonic Development in Zebrafish

Tan, Tianfeng; Yu, Richard Man Kit; Wu, Rudolf S.S.; Kong, Richard Yuen Chong

doi:10.1177/1177625017713193

Cited by 22 publications

(27 citation statements)

References 60 publications

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“…It was also reported that intermittent hypoxia (10% O 2 for 17 days) could cause abnormal synthesis of STAR protein and inhibit testosterone secretion in rats (Zhang et al 2013). In vivo studies with zebrafish also showed that upregulation of HIF1 expression could inhibit the synthesis of STAR protein (Tan et al 2017). Although these studies have proved that HIF1 represses STAR expression, the underlying molecular mechanism was not clarified.…”

Section: Discussionmentioning

confidence: 99%

HIF 1 inhibits STAR transcription and testosterone synthesis in murine Leydig cells

Wang

Zou

Yang

et al. 2019

Journal of Molecular Endocrinology

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Hypoxia-inducible factor-1 (HIF1) is a critical transcription factor involved in cell response to hypoxia. Under physiological conditions, its 'a' subunit is rapidly degraded in most tissues except testes. HIF1 is stably expressed in Leydig cells, which are the main source of testosterone for male, and might bind to the promoter region of steroidogenic acute regulatory protein (STAR), which is necessary for the testosterone synthesis, according to software analysis. This study aims to identify the binding sites of HIF1 on Star promoter and its transcriptional regulation of STAR to affect testosterone synthesis. Testosterone level and steroid synthesis-related proteins were determined in male Balb/C mice exposed to hypoxia (8% O 2 ). While HIF1 was upregulated, the testosterone level was significantly decreased. This was further confirmed by in vitro experiments with rat primary Leydig cells or TM3 cells exposed to hypoxia (1% O 2 ), CoCl 2 or DFX to raise HIF1. The decline of testosterone was reversed by pregnenolone but not cAMP, indicating the cholesterol transport disorder as the main cause. In agreement, STAR expression level was decreased in response to HIF1, while 3b-hydroxysteroid dehydrogenase, 17b-hydroxysteroid dehydrogenase and p450scc did not exhibit significant changes. By ChIP, EMSA supershift and dual-luciferase reporter assays, HIF1 was found to bind to the Star promoter region and repress the expression of STAR. Mutation assays identified three HIF1-binding sites on mouse Star promoter. These findings indicate that HIF1 represses STAR transcription through directly binding to the Staar promoter at −2082/−2078, −2064/−2060 and −1910/−1906, leading to the negative regulation of testosterone synthesis.

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Section: Discussionmentioning

confidence: 99%

HIF 1 inhibits STAR transcription and testosterone synthesis in murine Leydig cells

Wang

Zou

Yang

et al. 2019

Journal of Molecular Endocrinology

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“…Studies on the role of HIFs in the regulation of steroidogenesis in vitro are few, apart from those in zebra fish larvae that describe differential regulation of the enzymes involved in the steroid pathway (7,18,20). However, to the best of our knowledge, there are no mouse models to study the role of HPPs in adrenal cortical cells.…”

Section: Discussionmentioning

confidence: 99%

“…Previous in vitro studies and reports on HIF1α alterations in zebrafish larvae have suggested negative regulation of StAR, the mitochondrial cholesterol transporter (7,17,20). However, data on the effects of HPP alterations in adrenal cortex of mice is scant at best.…”

Section: Loss Of Phd2/hif1α In Adrenocortical Cells Impacts Gene Exprmentioning

confidence: 99%

“…As steroidogenesis is a tightly regulated process, proper control of adrenal cortex function relies on appropriate endocrine signaling, tissue integrity, and homeostasis (5). Accordingly, it has been suggested that inappropriately low pO2, or hypoxia, can lead to both structural changes in the adrenal cortex and interfere with hormone production (6)(7)(8)(9)(10).…”

Section: Introductionmentioning

confidence: 99%

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HIF1α is an essential regulator of steroidogenesis in the adrenal gland

Watts

Stein

Meneses

et al. 2020

Preprint

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AbstractEndogenous steroid hormones, especially glucocorticoids and mineralocorticoids, are essential for life regulating numerous physiological and pathological processes. These hormones derive from the adrenal cortex, and drastic or sustained changes in their circulatory levels affect multiple organ systems. Although a role for hypoxia pathway proteins (HPP) in steroidogenesis has been suggested, knowledge on the true impact of the HIFs (Hypoxia Inducible Factors) and oxygen sensors (HIF-prolyl hydroxylase domain-containing enzymes; PHDs) in the adrenocortical cells of vertebrates is scant. By creating a unique set of transgenic mouse lines, we reveal a prominent role for HIF1α in the synthesis of virtually all steroids under steady state conditions. Specifically, mice deficient in HIF1α in a part of the adrenocortical cells displayed enhanced levels of enzymes responsible for steroidogenesis and a cognate increase in circulatory steroid levels. These changes resulted in cytokine alterations and changes in the profile of circulatory mature hematopoietic cells. Conversely, HIF1α overexpression due to combined PHD2 and PHD3 deficiency in the adrenal cortex resulted in the opposite phenotype of insufficient steroid production due to impaired transcription of necessary enzymes. Based on these results, we propose HIF1α to be a central and vital regulator of steroidogenesis as its modulation in adrenocortical cells dramatically impacts hormone synthesis with systemic consequences. Additionally, these mice can have potential clinical significances as they may serve as essential tools to understand the pathophysiology of hormone modulations in a number of diseases associated with metabolic syndrome, auto-immunity or even cancer.

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“…A recent experimental study, however, revealed that Hif-1α is also required for proper embryonic development in fish. Overexpression of hif-1α mRNA in zebrafish resulted in developmental retardation and in a significant increase in developmental defects (Tan et al, 2017). Knockdown of hif-1α using morpholinos (see Glossary) in turn resulted in morphological abnormalities such as small head circumferences, deformed hearts, curved tails and a reduced growth rate (Tan et al, 2017).…”

Section: Expression Of Hif Isoforms During Developmentmentioning

confidence: 99%

Hypoxia-inducible transcription factors in fish: expression, function and interconnection with the circadian clock

Pelster

Egg

2018

Journal of Experimental Biology

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The hypoxia-inducible transcription factors are key regulators for the physiological response to low oxygen availability. In vertebrates, typically three Hif-α isoforms, Hif-1α, Hif-2α and Hif-3α, are expressed, each of which, together with Hif-1β, may form a functional heterodimer under hypoxic conditions, controlling expression of hundreds of genes. A teleost-specific whole-genome duplication complicates the analysis of isoform-specific functions in fish, but recent studies suggest that the existence of paralogues of a specific isoform opens up the possibility for a subfunctionalization. In contrast to during development inside the uterus, fish eggs are freely accessible and studies analyzing Hif expression in fish embryos during development have revealed that Hif proteins are not only controlling the hypoxic response, but are also crucial for proper development and organ differentiation. Significant advances have been made in our knowledge about tissue-specific functions of Hif proteins, especially with respect to gill or gonadal tissue. The hypoxia signalling pathway is known to be tightly and mutually intertwined with the circadian clock in zebrafish and mammals. Recently, a mechanistic explanation for the hypoxia-induced dampening of the transcriptional clock was detected in zebrafish, including also metabolically induced alterations of cellular redox signalling. In turn, MAP kinase-mediated HO signalling modulates the temporal expression of Hif-1α protein, similar to the redox regulation of the circadian clock itself. Once again, the zebrafish has emerged as an excellent model organism with which to explore these specific functional aspects of basic eukaryotic cell biology.

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Overexpression and Knockdown of Hypoxia-Inducible Factor 1 Disrupt the Expression of Steroidogenic Enzyme Genes and Early Embryonic Development in Zebrafish

Cited by 22 publications

References 60 publications

HIF 1 inhibits STAR transcription and testosterone synthesis in murine Leydig cells

HIF 1 inhibits STAR transcription and testosterone synthesis in murine Leydig cells

HIF1α is an essential regulator of steroidogenesis in the adrenal gland

Hypoxia-inducible transcription factors in fish: expression, function and interconnection with the circadian clock

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