Activin stimulates goldfish FSH biosynthesis by enhancing FSHβ promoter activity

Ge, Wei; Ko, Nga-Ling; Pang, F.; Chung, Me-Fong; Lin, Showe‐Mei; Yuen, Chi-Wai; Lau, Man-Tat; Liu, Lin; Sohn, Young Chang; Kobayashi, Makito; Aida, Katsumi

doi:10.1023/b:fish.0000030478.31396.bb

Cited by 6 publications

(2 citation statements)

References 24 publications

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“…We previously showed that goldfish fshb promoter strongly responded to activin in the LβT-2 cells (Ge et al, 2003 ), and co-transfection with Smad expression vectors, especially Smad3, dramatically enhanced the expression level of the reporter, suggesting the presence of Smad regulatory elements in the promoter (Lau and Ge, 2005 ). To localize the potential regulatory elements, we performed this experiment by examining the activity of goldfish fshb promoter with decreasing size in the LβT-2 cells (a gonadotroph cell line) in the presence of goldfish Smad2 or Smad3.…”

Section: Resultsmentioning

confidence: 99%

“…In the pituitary, activin is a key modulator of FSHβ expression and FSH secretion (Ling et al, 1986a , b ; Vale et al, 1986 ; Weiss et al, 1992 , 1995 ). In the goldfish, our previous results have demonstrated that activin stimulates FSHβ ( fshb ) expression (Yam et al, 1999 ; Yuen and Ge, 2004 ) and its stimulatory effect is exerted at the promoter level (Ge et al, 2003 ). Similar effect has recently been reported in the zebrafish (Lin and Ge, 2009 ) and the European eel (Aroua et al, 2011 ).…”

Section: Discussionmentioning

confidence: 99%

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Identification of Smad Response Elements in the Promoter of Goldfish FSHβ Gene and Evidence for Their Mediation of Activin and GnRH Stimulation of FSHβ Expression

Lau¹,

Lin²,

Ge³

2012

Front. Endocrin.

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As an essential hormone regulating gonads in vertebrates, the biosynthesis and secretion of follicle-stimulating hormone (FSH) is controlled by a variety of endocrine and paracrine factors in both mammalian and non-mammalian vertebrates. Activin was initially discovered in the ovary for its specific stimulation of FSH secretion by the pituitary cells. Our earlier studies in fish have shown that activin stimulates FSHβ but suppresses LHβ expression in both the goldfish and zebrafish. Further experiments showed that the regulation of FSHβ in fish occurred at the promoter level involving Smads, in particular Smad3. To further understand the mechanisms by which activin/Smad regulates FSHβ transcription, the present study was undertaken to analyze the promoter of goldfish FSHβ gene (fshb) with the aim to identify potential cis-regulatory elements responsible for activin/Smad stimulation. Both serial deletion and site-directed mutagenesis were used, and the promoter activity was tested in the LβT-2 cells, a murine gonadotroph cell line. The reporter constructs of goldfish FSHβ promoter-SEAP (secreted alkaline phosphatase) were co-transfected with an expression plasmid for Smads (2 or 3) followed by measurement of SEAP activity in the medium. Two putative Smad responsive elements were identified in the promoter at distal and proximal regions, respectively. The distal site contained a consensus Smad binding element (AGAC, −1675/−1672) whereas the proximal site (GACCTTGA, −212/−205) was identical to an SF-1 binding site reported in humans, which was preceded by a sequence (AACACTGA) highly conserved between fish and mammals. The proximal site also seemed to be involved in mediating stimulation of FSHβ expression by gonadotropin-releasing hormone and its potential interaction with activin. In conclusion, we have identified two potential cis-regulatory elements in the promoter of goldfish FSHβ that are responsible for activin-induced expression of the gene. Since activin stimulation of FSHβ expression is functionally conserved in fish and mammals, our findings contribute to the understanding of the fundamental mechanisms of this regulation across vertebrates.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Identification of Smad Response Elements in the Promoter of Goldfish FSHβ Gene and Evidence for Their Mediation of Activin and GnRH Stimulation of FSHβ Expression

Lau¹,

Lin²,

Ge³

2012

Front. Endocrin.

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Characterization of sea bass FSHβ 5′ flanking region: transcriptional control by 17β-estradiol

Muriach

Carrillo

Zanuy

et al. 2013

Fish Physiol Biochem

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The sea bass follicle-stimulating hormone 5' flanking region (sbFSHβ 5' FR) was cloned and characterized in order to study the molecular mechanisms underlying transcriptional regulation of the sbFSHβ gene. Analysis of the ~3.5 kb of this region revealed the presence of several putative cis-acting elements, including steroid hormone response elements, cAMP response elements, pituitary-specific transcription factor response elements, activator protein-1 response elements and TATA sequence. Deleted constructs containing ~3.5 kb of the sbFSHβ 5' FR fused to a luciferase reporter gene were transiently transfected into human embryonic kidney (HEK 293) and mouse mature gonadotrope (LβT2) cell lines. The sbFSHβ 5' FR was efficiently expressed under basal conditions in LβT2 but not in HEK 293, pointing to both positive and negative regulatory elements. In order to elucidate the estrogen-mediated sbFSHβ transcriptional activity, in vitro treatments with 17β-estradiol were carried out on primary cultures of pituitary cells and LβT2 cells transiently expressing luciferase under the control of sbFSHβ 5' FR. Overall, these results demonstrate that 17β-estradiol inhibits sbFSHβ gene expression directly at the level of the pituitary. However, it was also shown that estrogen did not induce changes of the sbFSH promoter-directed luciferase activity, suggesting that sbFSHβ 5'FR (~3.5 kb) activity is cell type dependent and its estrogen regulation could require cis-acting elements located upstream of the promoter region, which is characterized in this article.

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Expression and regulation of Smad2 by gonadotropins in the protogynous hermaphroditic ricefield eel (Monopterus albus)

Deng

Xiong

et al. 2020

Fish Physiol Biochem

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Activin stimulates goldfish FSH biosynthesis by enhancing FSHβ promoter activity

Cited by 6 publications

References 24 publications

Identification of Smad Response Elements in the Promoter of Goldfish FSHβ Gene and Evidence for Their Mediation of Activin and GnRH Stimulation of FSHβ Expression

Identification of Smad Response Elements in the Promoter of Goldfish FSHβ Gene and Evidence for Their Mediation of Activin and GnRH Stimulation of FSHβ Expression

Characterization of sea bass FSHβ 5′ flanking region: transcriptional control by 17β-estradiol

Expression and regulation of Smad2 by gonadotropins in the protogynous hermaphroditic ricefield eel (Monopterus albus)

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