Cloning and Characterization of Cholesterol 25-Hydroxylase (ch25h) From a Marine Teleost, Chinese Tongue Sole (Cynoglossus semilaevis), and Its Gene Expressions in Response to Dietary Arachidonic Acid

Abstract

Our previous studies have shown that ARA regulated the gonadal steroidogenesis and the synthesis of gonadotrophin-releasing hormone (GnRH) in the brain in a gender-dependent manner in Chinese tongue sole, a marine teleost with typical sex dimorphism. As a following up-study, the current study aimed to clone and characterize a gene responding to dietary ARA differently between males and females, cholesterol 25-hydroxylase (ch25h), which has important roles in cholesterol and lipid metabolism of mammals, but is rarely investigated in fish. The full-length cDNA of Chinese tongue sole ch25h was cloned and characterized, and its transcription in the gonads, brain and liver of both males and females in response to dietary ARA levels (0.34, 2.53, and 9.63% of TFA) was investigated. The Chinese tongue sole Ch25h, which putatively is Ch25h subtype B, shared moderate identity to its known orthologs of other teleost and lower identity to human Ch25h. It has high transcription levels in the gonads, followed by skin and muscle, but low levels in the intestine, spleen, and kidney. High ARA levels significantly increased the ch25h transcription in the gonads and brain of male fish, but did not affect the transcription in the females. However, the effect of dietary ARA on ch25h transcription in the liver showed an opposite gender-difference pattern to those in the gonads and brain. To our knowledge, this is the first study in marine teleost investigating the nutritional regulation of ch25h expression.

Nutritional immunomodulation of Atlantic salmon response to Renibacterium salmoninarum bacterin

“…Furthermore, ch25ha was one of the top contributors to the dissimilarities between the switched-diet group and both the high-18:2ω6 and high-18:3ω3 groups ( Figure 6C and Supplementary Figure S2C ). CH25H is a membrane-associated enzyme that catalyzes the formation of 25-hydroxycholesterol from cholesterol ( Xu et al, 2020 ). Furthermore, CH25H showed an interferon-independent antiviral and immunoregulatory activity in teleosts [e.g., zebrafish and Chinese tongue sole ( Cynoglossus semilaevis )] ( Pereiro et al, 2017 ; Xu et al, 2020 ).…”

Arachidonic acid matters

“…Sexually dimorphic transcription of production‐related genes in response to dietary ARA administration was observed in two recent studies in tongue sole 158,159 . Specifically, two important genes, the melanin‐concentrating hormone 2 preprotein ( pmch2 ), which serves as an integratory mediator between appetitive behaviours, energy balance and reproduction, and the cholesterol 25‐hydroxylase ( ch25h ), which has important roles in cholesterol and lipid metabolism, showed a typical sexually dimorphic response to dietary ARA supplementation 158,159 …”

“…Sexually dimorphic transcription of production-related genes in response to dietary ARA administration was observed in two recent studies in tongue sole. 158,159 Specifically, two important genes, the melanin-concentrating hormone 2 preprotein (pmch2), which serves as an integratory mediator between appetitive behaviours, energy balance and reproduction, and the cholesterol 25-hydroxylase (ch25h), which has important roles in cholesterol and lipid metabolism, showed a typical sexually dimorphic response to dietary ARA supplementation. 158,159 Regarding the effects of ARA on gonadal gene expression of key proteins in steroidogenesis, the available results and evidences suggest the existence of important differences not only depending on fish sex, but also depending on gonadal developmental stage.…”

“…158,159 Specifically, two important genes, the melanin-concentrating hormone 2 preprotein (pmch2), which serves as an integratory mediator between appetitive behaviours, energy balance and reproduction, and the cholesterol 25-hydroxylase (ch25h), which has important roles in cholesterol and lipid metabolism, showed a typical sexually dimorphic response to dietary ARA supplementation. 158,159 Regarding the effects of ARA on gonadal gene expression of key proteins in steroidogenesis, the available results and evidences suggest the existence of important differences not only depending on fish sex, but also depending on gonadal developmental stage. In tongue sole, a medium level of dietary ARA (5.14% TFA) upregulated the expression of follicle-stimulating hormone receptor (fshr), steroidogenic acute regulatory protein (star), cholesterol side-chain cleavage enzyme (p450ssc), 3β-and 17 β-hydroxysteroid dehydrogenase (3β-hsd, and 17β-hsd) in immature females, but downregulated the gene expression of fshr, 3βhsd, 17β-hsd, and aromatase in mature females.…”

25-Hydroxycholesterol as a Signaling Molecule of the Nervous System

“…Both CH25H expression and 25-HC production increase in the adipose tissue macrophages with the increase in the body mass index and fat intake [35]. Consumption of excess of arachidonic acid may elevate CH25H levels in the liver and brain [36]. It has been shown that the blood plasma concentration of 25-HC in patients with the vitamin D defi ciency increases signifi cantly after diet supplementation with vitamin D (50,000 IU per week for eight weeks) in combination with phototherapy [37].…”