Regulation of fish gonadotropins

Zvi Yaron; Gal Gur; Philippa Melamed; Hanna Rosenfeld; Abigail Elizur; Berta Levavi-Sivan

doi:10.1016/S0074-7696(05)25004-0

Regulation of fish gonadotropins

Zvi Yaron^*, Gal Gur, Philippa Melamed, Hanna Rosenfeld, Abigail Elizur, Berta Levavi-Sivan

^*Corresponding author for this work

Department of Animal Sciences

Research output: Contribution to journal › Review article › peer-review

384 Scopus citations

Abstract

Neurohormones similar to those of mammals are carried in fish by hypothalamic nerve fibers to regulate directly follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Gonadotropin-releasing hormone (GnRH) stimulates the secretion of FSH and LH and the expression of the glycoprotein hormone α (GPα), FSHβ, and LHβ, as well as their secretion. Its signal transduction leading to LH release is similar to that in mammals although the involvement of cyclic AMP-protein kinase A (cAMP-PKA) cannot be ruled out. Dopamine (DA) acting through DA D₂ type receptors may inhibit LH release, but not that of FSH, at sites distal to activation of protein kinase C (PKC) and PKA. GnRH increases the steady-state levels of GPα, LHβ, and FSHβ mRNAs. Pituitary adenylate cyclase-activating polypeptide (PACAP) 38 and neuropeptide Y (NPY) potentiate GnRH effect on gonadotropic cells, and also act directly on the pituitary cells. Whereas PACAP increases all three subunit mRNAs, NPY has no effect on that of FSHβ. The effect of these peptides on the expression of the gonadotropin subunit genes is transduced differentially; GnRH regulates GPα and LHβ via PKC-ERK and PKA-ERK cascades, while affecting the FSHβ transcript through a PKA-dependent but ERK-independent cascade. The signals of both NPY and PACAP are transduced via PKC and PKA, each converging at the ERK level. NPY regulates only GPα- and LHβ-subunit genes whereas PACAP regulates the FSHβ subunit as well. Like those of the mammalian counterparts, the coho salmon LHβ gene promoter is driven by a strong proximal tripartite element to which three different transcription factors bind. These include Sf-1 and Pitx-1 as in mammals, but the function of the Egr-1 appears to have been replaced by the estrogen receptor (ER). The GnRH responsive region in tilapia FSHβ 5′ flanking region spans the canonical AP1 and CRE motifs implicating both elements in conferring GnRH responsiveness. Generally, high levels of gonadal steroids are associated with high LHβ transcript levels whereas those of FSHβ are reduced when pituitary cells are exposed to high steroid levels. Gonadal or hypophyseal activin also participate in the regulation of FSHβ and LHβ mRNA levels. However, gonadal effects are dependent on the gender and stage of maturity of the fish.

Original language	English
Pages (from-to)	131-185
Number of pages	55
Journal	International Review of Cytology
Volume	225
DOIs	https://doi.org/10.1016/S0074-7696(05)25004-0
State	Published - 2003

Bibliographical note

Funding Information:
Antonopoulou, E., Swanson, E, Mayer, I., and Borg, B. (1999b). Feedback control of gonadotropins in A~lantic salmon, Salmo salar, male parr--II, aromatase inhibitor and androgen effects. Gen. Comp. EndocrinoL 114, 142-150. Arora, K. K., Krsmanovic, L. Z., Mores, N., O'Farrell, H., and Catt, K. J. (1998). Mediation of cyclic AMP signaling by the first intracellular loop of the gonadotropin-releasing hormone receptor. J. Biol. Chem. 273, 25581-25586. Bauer, H., Meier, A., Hild, M., Stachel, S., Economides, A., Hazelett, D., Harland, R. M., and Hammerschmidt, M. (1998). Follistatin and noggin are excluded from the zebrafish organizer. Dev. Biol. 204, 488-507. Blomenr6hr, M., Bogerd, J., Leurs, R., Schulz, R. W., Tensen, C. E, Zandbergen, M. A., and Goos, H. J. Th. (1997). Differences in structure-function relations between nonmammalian and mammalian gonadotropin-releasing hormone receptors. Biochem. Biophys. Res. Commun. 238, 517-522. Blomqvist, A. G., Soderberg, C., Lundell, I., Milner, R. J., and Larhammar, D. (1992). Strong evo-lutionary conservation of neuropeptide Y: Sequence of chicken, goldfish and Torpedo marmorata DNA clones. Proc. Natl. Acad. Sci. USA 89, 2350-2354. Borg, B., Antonopoulou, E., Mayer, I., Andersson, E., Berglund, I., and Swanson, E (1998). Effects of gonadectomy and androgen treatments on pituitary and plasma levels of gonadotropius in mature male Atlantic salmon, Salmo salat; parr-poshive feedback control of both gonadotropins. Biol. Reprod. 58, 814-820. Bourne, G. A., and Baldwin, D. M. (1987). Evidence for cAMP as a mediator of gonadotropin secretion from male pituitaries. Am. J. Physiol. 253, E296-E299. Breton, B., Mikolajczyk, T., Weil, C., Danger, J. M., and Vaudry, H. (1990). Studies on the mode of action of neuropeptide Y (NPY) on maturational gonadotropin (GtH) secretion from perifused rainbow trout pituitary glands. Fish Physiol. Biochem. 8, 339-346. Breton, B., Sambroni, E., Govoroun, M., and Weil, C. (1997). Effects of steroids on GtH I and GtH II secretion and pituitary concentration in the immature rainbow trout Oncorhynchus mykiss. C. R. Acad. Sci. Ser III 320, 783-789. Breton, B., Govoronn, M., and Mikolajczyk, T. (1998). GTH I and GTH II secretion profiles during the reproductive cycle in female rainbow trout: Relationship with pituitary responsiveness to GnRH-A stimulation. Gen. Comp. Endocrinol. 111, 38-50. Burrin, J. M., Aylwin, S. J., Holdstock, J. G., and Sahye, U. (1998). Mechanism of action of pituitary adenylate cyclase-activating polypeptide on human glycoprotein hormone aT3-1 gonadotropes. Endocrinology 139, 1731-1737. Burzawa-Gerard, E. (1982). Chemical data on pituitary gonadotropins and their implication to evolu-tion. Can. J. Fish. Aquat. Sci. 39, 80-91. Call, G. B., and Wolfe, M. W. (2002). Species differences in GnRH activation of the LH~ promoter: Role of Egrl and Spl. Mol. Cell. Endocrinol. 189, 85-96. Cavaco, J. E. B., Van Baal, J., Van Dijk, W., Hassing, G. A. M., Goos, H. J. T., and Schulz, R. W. (2001). Steroid hormones stimulate gonadotrophs in juvenile male African catfish (Clarias gariepinus). Biol. Reprod. 64, 1358-1365. Cerd~i-Reverter, J. M., and Larhammar, D. (2000). Neuropeptide Y family of peptides: Structure, anatomical expression, function, and molecular evolution. Biochem. Cell Biol. 78, 371-392. Cerd~-Reverter, J. M., Martinez-Rodriguez, G., Zanuy, S., Carrillo, M., and Larhammar, D. (1998). Cloning of neuropeptide Y, peptide YY and peptideY from sea bass (Dicentrarchus labrax), a marine teleost. Ann. N. Y Acad. Sci. 839, 493-495. Chang, J. E, and Jobin, R. M. (1994). Regulation of gonadotropin release in vertebrates: A comparison of GnRH mechanisms of action. In "Perspectives in Comparative Endocrinology" (K. G. Davey, R. E. Peter, and S. S. Tobe, Eds.), pp. 41-51. National Research Council of Canada, Ottawa. Chang, J. P., Peter, R. E., Nahorniak, C. S., and Sokolowska, M. (1984a). Effect of catecholaminergic agonists and antagonists on serum gonadotropin concentrations and ovulation in goldfish: Evidence for specificity of dopamine inhibition on gonadotropin secretion. Gen. Comp. Endocrinol. 55, 351-360.

Keywords

Activin
Arachidonic acid
CAMP
Calmodulin
ERE
ERK
Egr-1
Estradiol
FSH
GnRH
Inhibin
LH
MAPK
MRNA
Molecular evolution
NPY
Oreochromis
PACAP
Pituitary
Promoter
Ptx-1
Sf-1
Testosterone

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10.1016/S0074-7696(05)25004-0

Cite this

@article{2626ec9b34dc42b7b0c77147535adc37,

title = "Regulation of fish gonadotropins",

abstract = "Neurohormones similar to those of mammals are carried in fish by hypothalamic nerve fibers to regulate directly follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Gonadotropin-releasing hormone (GnRH) stimulates the secretion of FSH and LH and the expression of the glycoprotein hormone α (GPα), FSHβ, and LHβ, as well as their secretion. Its signal transduction leading to LH release is similar to that in mammals although the involvement of cyclic AMP-protein kinase A (cAMP-PKA) cannot be ruled out. Dopamine (DA) acting through DA D2 type receptors may inhibit LH release, but not that of FSH, at sites distal to activation of protein kinase C (PKC) and PKA. GnRH increases the steady-state levels of GPα, LHβ, and FSHβ mRNAs. Pituitary adenylate cyclase-activating polypeptide (PACAP) 38 and neuropeptide Y (NPY) potentiate GnRH effect on gonadotropic cells, and also act directly on the pituitary cells. Whereas PACAP increases all three subunit mRNAs, NPY has no effect on that of FSHβ. The effect of these peptides on the expression of the gonadotropin subunit genes is transduced differentially; GnRH regulates GPα and LHβ via PKC-ERK and PKA-ERK cascades, while affecting the FSHβ transcript through a PKA-dependent but ERK-independent cascade. The signals of both NPY and PACAP are transduced via PKC and PKA, each converging at the ERK level. NPY regulates only GPα- and LHβ-subunit genes whereas PACAP regulates the FSHβ subunit as well. Like those of the mammalian counterparts, the coho salmon LHβ gene promoter is driven by a strong proximal tripartite element to which three different transcription factors bind. These include Sf-1 and Pitx-1 as in mammals, but the function of the Egr-1 appears to have been replaced by the estrogen receptor (ER). The GnRH responsive region in tilapia FSHβ 5′ flanking region spans the canonical AP1 and CRE motifs implicating both elements in conferring GnRH responsiveness. Generally, high levels of gonadal steroids are associated with high LHβ transcript levels whereas those of FSHβ are reduced when pituitary cells are exposed to high steroid levels. Gonadal or hypophyseal activin also participate in the regulation of FSHβ and LHβ mRNA levels. However, gonadal effects are dependent on the gender and stage of maturity of the fish.",

keywords = "Activin, Arachidonic acid, CAMP, Calmodulin, ERE, ERK, Egr-1, Estradiol, FSH, GnRH, Inhibin, LH, MAPK, MRNA, Molecular evolution, NPY, Oreochromis, PACAP, Pituitary, Promoter, Ptx-1, Sf-1, Testosterone",

author = "Zvi Yaron and Gal Gur and Philippa Melamed and Hanna Rosenfeld and Abigail Elizur and Berta Levavi-Sivan",

note = "Funding Information: Antonopoulou, E., Swanson, E, Mayer, I., and Borg, B. (1999b). Feedback control of gonadotropins in A~lantic salmon, Salmo salar, male parr--II, aromatase inhibitor and androgen effects. Gen. Comp. EndocrinoL 114, 142-150. Arora, K. K., Krsmanovic, L. Z., Mores, N., O'Farrell, H., and Catt, K. J. (1998). Mediation of cyclic AMP signaling by the first intracellular loop of the gonadotropin-releasing hormone receptor. J. Biol. Chem. 273, 25581-25586. Bauer, H., Meier, A., Hild, M., Stachel, S., Economides, A., Hazelett, D., Harland, R. M., and Hammerschmidt, M. (1998). Follistatin and noggin are excluded from the zebrafish organizer. Dev. Biol. 204, 488-507. Blomenr6hr, M., Bogerd, J., Leurs, R., Schulz, R. W., Tensen, C. E, Zandbergen, M. A., and Goos, H. J. Th. (1997). Differences in structure-function relations between nonmammalian and mammalian gonadotropin-releasing hormone receptors. Biochem. Biophys. Res. Commun. 238, 517-522. Blomqvist, A. G., Soderberg, C., Lundell, I., Milner, R. J., and Larhammar, D. (1992). Strong evo-lutionary conservation of neuropeptide Y: Sequence of chicken, goldfish and Torpedo marmorata DNA clones. Proc. Natl. Acad. Sci. USA 89, 2350-2354. Borg, B., Antonopoulou, E., Mayer, I., Andersson, E., Berglund, I., and Swanson, E (1998). Effects of gonadectomy and androgen treatments on pituitary and plasma levels of gonadotropius in mature male Atlantic salmon, Salmo salat; parr-poshive feedback control of both gonadotropins. Biol. Reprod. 58, 814-820. Bourne, G. A., and Baldwin, D. M. (1987). Evidence for cAMP as a mediator of gonadotropin secretion from male pituitaries. Am. J. Physiol. 253, E296-E299. Breton, B., Mikolajczyk, T., Weil, C., Danger, J. M., and Vaudry, H. (1990). Studies on the mode of action of neuropeptide Y (NPY) on maturational gonadotropin (GtH) secretion from perifused rainbow trout pituitary glands. Fish Physiol. Biochem. 8, 339-346. Breton, B., Sambroni, E., Govoroun, M., and Weil, C. (1997). Effects of steroids on GtH I and GtH II secretion and pituitary concentration in the immature rainbow trout Oncorhynchus mykiss. C. R. Acad. Sci. Ser III 320, 783-789. Breton, B., Govoronn, M., and Mikolajczyk, T. (1998). GTH I and GTH II secretion profiles during the reproductive cycle in female rainbow trout: Relationship with pituitary responsiveness to GnRH-A stimulation. Gen. Comp. Endocrinol. 111, 38-50. Burrin, J. M., Aylwin, S. J., Holdstock, J. G., and Sahye, U. (1998). Mechanism of action of pituitary adenylate cyclase-activating polypeptide on human glycoprotein hormone aT3-1 gonadotropes. Endocrinology 139, 1731-1737. Burzawa-Gerard, E. (1982). Chemical data on pituitary gonadotropins and their implication to evolu-tion. Can. J. Fish. Aquat. Sci. 39, 80-91. Call, G. B., and Wolfe, M. W. (2002). Species differences in GnRH activation of the LH~ promoter: Role of Egrl and Spl. Mol. Cell. Endocrinol. 189, 85-96. Cavaco, J. E. B., Van Baal, J., Van Dijk, W., Hassing, G. A. M., Goos, H. J. T., and Schulz, R. W. (2001). Steroid hormones stimulate gonadotrophs in juvenile male African catfish (Clarias gariepinus). Biol. Reprod. 64, 1358-1365. Cerd~i-Reverter, J. M., and Larhammar, D. (2000). Neuropeptide Y family of peptides: Structure, anatomical expression, function, and molecular evolution. Biochem. Cell Biol. 78, 371-392. Cerd~-Reverter, J. M., Martinez-Rodriguez, G., Zanuy, S., Carrillo, M., and Larhammar, D. (1998). Cloning of neuropeptide Y, peptide YY and peptideY from sea bass (Dicentrarchus labrax), a marine teleost. Ann. N. Y Acad. Sci. 839, 493-495. Chang, J. E, and Jobin, R. M. (1994). Regulation of gonadotropin release in vertebrates: A comparison of GnRH mechanisms of action. In {"}Perspectives in Comparative Endocrinology{"} (K. G. Davey, R. E. Peter, and S. S. Tobe, Eds.), pp. 41-51. National Research Council of Canada, Ottawa. Chang, J. P., Peter, R. E., Nahorniak, C. S., and Sokolowska, M. (1984a). Effect of catecholaminergic agonists and antagonists on serum gonadotropin concentrations and ovulation in goldfish: Evidence for specificity of dopamine inhibition on gonadotropin secretion. Gen. Comp. Endocrinol. 55, 351-360.",

year = "2003",

doi = "10.1016/S0074-7696(05)25004-0",

language = "אנגלית",

volume = "225",

pages = "131--185",

journal = "International Review of Cytology",

issn = "0074-7696",

publisher = "Elsevier Inc.",

}

TY - JOUR

T1 - Regulation of fish gonadotropins

AU - Yaron, Zvi

AU - Gur, Gal

AU - Melamed, Philippa

AU - Rosenfeld, Hanna

AU - Elizur, Abigail

AU - Levavi-Sivan, Berta

N1 - Funding Information: Antonopoulou, E., Swanson, E, Mayer, I., and Borg, B. (1999b). Feedback control of gonadotropins in A~lantic salmon, Salmo salar, male parr--II, aromatase inhibitor and androgen effects. Gen. Comp. EndocrinoL 114, 142-150. Arora, K. K., Krsmanovic, L. Z., Mores, N., O'Farrell, H., and Catt, K. J. (1998). Mediation of cyclic AMP signaling by the first intracellular loop of the gonadotropin-releasing hormone receptor. J. Biol. Chem. 273, 25581-25586. Bauer, H., Meier, A., Hild, M., Stachel, S., Economides, A., Hazelett, D., Harland, R. M., and Hammerschmidt, M. (1998). Follistatin and noggin are excluded from the zebrafish organizer. Dev. Biol. 204, 488-507. Blomenr6hr, M., Bogerd, J., Leurs, R., Schulz, R. W., Tensen, C. E, Zandbergen, M. A., and Goos, H. J. Th. (1997). Differences in structure-function relations between nonmammalian and mammalian gonadotropin-releasing hormone receptors. Biochem. Biophys. Res. Commun. 238, 517-522. Blomqvist, A. G., Soderberg, C., Lundell, I., Milner, R. J., and Larhammar, D. (1992). Strong evo-lutionary conservation of neuropeptide Y: Sequence of chicken, goldfish and Torpedo marmorata DNA clones. Proc. Natl. Acad. Sci. USA 89, 2350-2354. Borg, B., Antonopoulou, E., Mayer, I., Andersson, E., Berglund, I., and Swanson, E (1998). Effects of gonadectomy and androgen treatments on pituitary and plasma levels of gonadotropius in mature male Atlantic salmon, Salmo salat; parr-poshive feedback control of both gonadotropins. Biol. Reprod. 58, 814-820. Bourne, G. A., and Baldwin, D. M. (1987). Evidence for cAMP as a mediator of gonadotropin secretion from male pituitaries. Am. J. Physiol. 253, E296-E299. Breton, B., Mikolajczyk, T., Weil, C., Danger, J. M., and Vaudry, H. (1990). Studies on the mode of action of neuropeptide Y (NPY) on maturational gonadotropin (GtH) secretion from perifused rainbow trout pituitary glands. Fish Physiol. Biochem. 8, 339-346. Breton, B., Sambroni, E., Govoroun, M., and Weil, C. (1997). Effects of steroids on GtH I and GtH II secretion and pituitary concentration in the immature rainbow trout Oncorhynchus mykiss. C. R. Acad. Sci. Ser III 320, 783-789. Breton, B., Govoronn, M., and Mikolajczyk, T. (1998). GTH I and GTH II secretion profiles during the reproductive cycle in female rainbow trout: Relationship with pituitary responsiveness to GnRH-A stimulation. Gen. Comp. Endocrinol. 111, 38-50. Burrin, J. M., Aylwin, S. J., Holdstock, J. G., and Sahye, U. (1998). Mechanism of action of pituitary adenylate cyclase-activating polypeptide on human glycoprotein hormone aT3-1 gonadotropes. Endocrinology 139, 1731-1737. Burzawa-Gerard, E. (1982). Chemical data on pituitary gonadotropins and their implication to evolu-tion. Can. J. Fish. Aquat. Sci. 39, 80-91. Call, G. B., and Wolfe, M. W. (2002). Species differences in GnRH activation of the LH~ promoter: Role of Egrl and Spl. Mol. Cell. Endocrinol. 189, 85-96. Cavaco, J. E. B., Van Baal, J., Van Dijk, W., Hassing, G. A. M., Goos, H. J. T., and Schulz, R. W. (2001). Steroid hormones stimulate gonadotrophs in juvenile male African catfish (Clarias gariepinus). Biol. Reprod. 64, 1358-1365. Cerd~i-Reverter, J. M., and Larhammar, D. (2000). Neuropeptide Y family of peptides: Structure, anatomical expression, function, and molecular evolution. Biochem. Cell Biol. 78, 371-392. Cerd~-Reverter, J. M., Martinez-Rodriguez, G., Zanuy, S., Carrillo, M., and Larhammar, D. (1998). Cloning of neuropeptide Y, peptide YY and peptideY from sea bass (Dicentrarchus labrax), a marine teleost. Ann. N. Y Acad. Sci. 839, 493-495. Chang, J. E, and Jobin, R. M. (1994). Regulation of gonadotropin release in vertebrates: A comparison of GnRH mechanisms of action. In "Perspectives in Comparative Endocrinology" (K. G. Davey, R. E. Peter, and S. S. Tobe, Eds.), pp. 41-51. National Research Council of Canada, Ottawa. Chang, J. P., Peter, R. E., Nahorniak, C. S., and Sokolowska, M. (1984a). Effect of catecholaminergic agonists and antagonists on serum gonadotropin concentrations and ovulation in goldfish: Evidence for specificity of dopamine inhibition on gonadotropin secretion. Gen. Comp. Endocrinol. 55, 351-360.

PY - 2003

Y1 - 2003

N2 - Neurohormones similar to those of mammals are carried in fish by hypothalamic nerve fibers to regulate directly follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Gonadotropin-releasing hormone (GnRH) stimulates the secretion of FSH and LH and the expression of the glycoprotein hormone α (GPα), FSHβ, and LHβ, as well as their secretion. Its signal transduction leading to LH release is similar to that in mammals although the involvement of cyclic AMP-protein kinase A (cAMP-PKA) cannot be ruled out. Dopamine (DA) acting through DA D2 type receptors may inhibit LH release, but not that of FSH, at sites distal to activation of protein kinase C (PKC) and PKA. GnRH increases the steady-state levels of GPα, LHβ, and FSHβ mRNAs. Pituitary adenylate cyclase-activating polypeptide (PACAP) 38 and neuropeptide Y (NPY) potentiate GnRH effect on gonadotropic cells, and also act directly on the pituitary cells. Whereas PACAP increases all three subunit mRNAs, NPY has no effect on that of FSHβ. The effect of these peptides on the expression of the gonadotropin subunit genes is transduced differentially; GnRH regulates GPα and LHβ via PKC-ERK and PKA-ERK cascades, while affecting the FSHβ transcript through a PKA-dependent but ERK-independent cascade. The signals of both NPY and PACAP are transduced via PKC and PKA, each converging at the ERK level. NPY regulates only GPα- and LHβ-subunit genes whereas PACAP regulates the FSHβ subunit as well. Like those of the mammalian counterparts, the coho salmon LHβ gene promoter is driven by a strong proximal tripartite element to which three different transcription factors bind. These include Sf-1 and Pitx-1 as in mammals, but the function of the Egr-1 appears to have been replaced by the estrogen receptor (ER). The GnRH responsive region in tilapia FSHβ 5′ flanking region spans the canonical AP1 and CRE motifs implicating both elements in conferring GnRH responsiveness. Generally, high levels of gonadal steroids are associated with high LHβ transcript levels whereas those of FSHβ are reduced when pituitary cells are exposed to high steroid levels. Gonadal or hypophyseal activin also participate in the regulation of FSHβ and LHβ mRNA levels. However, gonadal effects are dependent on the gender and stage of maturity of the fish.

AB - Neurohormones similar to those of mammals are carried in fish by hypothalamic nerve fibers to regulate directly follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Gonadotropin-releasing hormone (GnRH) stimulates the secretion of FSH and LH and the expression of the glycoprotein hormone α (GPα), FSHβ, and LHβ, as well as their secretion. Its signal transduction leading to LH release is similar to that in mammals although the involvement of cyclic AMP-protein kinase A (cAMP-PKA) cannot be ruled out. Dopamine (DA) acting through DA D2 type receptors may inhibit LH release, but not that of FSH, at sites distal to activation of protein kinase C (PKC) and PKA. GnRH increases the steady-state levels of GPα, LHβ, and FSHβ mRNAs. Pituitary adenylate cyclase-activating polypeptide (PACAP) 38 and neuropeptide Y (NPY) potentiate GnRH effect on gonadotropic cells, and also act directly on the pituitary cells. Whereas PACAP increases all three subunit mRNAs, NPY has no effect on that of FSHβ. The effect of these peptides on the expression of the gonadotropin subunit genes is transduced differentially; GnRH regulates GPα and LHβ via PKC-ERK and PKA-ERK cascades, while affecting the FSHβ transcript through a PKA-dependent but ERK-independent cascade. The signals of both NPY and PACAP are transduced via PKC and PKA, each converging at the ERK level. NPY regulates only GPα- and LHβ-subunit genes whereas PACAP regulates the FSHβ subunit as well. Like those of the mammalian counterparts, the coho salmon LHβ gene promoter is driven by a strong proximal tripartite element to which three different transcription factors bind. These include Sf-1 and Pitx-1 as in mammals, but the function of the Egr-1 appears to have been replaced by the estrogen receptor (ER). The GnRH responsive region in tilapia FSHβ 5′ flanking region spans the canonical AP1 and CRE motifs implicating both elements in conferring GnRH responsiveness. Generally, high levels of gonadal steroids are associated with high LHβ transcript levels whereas those of FSHβ are reduced when pituitary cells are exposed to high steroid levels. Gonadal or hypophyseal activin also participate in the regulation of FSHβ and LHβ mRNA levels. However, gonadal effects are dependent on the gender and stage of maturity of the fish.

KW - Activin

KW - Arachidonic acid

KW - CAMP

KW - Calmodulin

KW - ERE

KW - ERK

KW - Egr-1

KW - Estradiol

KW - FSH

KW - GnRH

KW - Inhibin

KW - LH

KW - MAPK

KW - MRNA

KW - Molecular evolution

KW - NPY

KW - Oreochromis

KW - PACAP

KW - Pituitary

KW - Promoter

KW - Ptx-1

KW - Sf-1

KW - Testosterone

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U2 - 10.1016/S0074-7696(05)25004-0

DO - 10.1016/S0074-7696(05)25004-0

M3 - ???researchoutput.researchoutputtypes.contributiontojournal.systematicreview???

C2 - 12696592

AN - SCOPUS:0037268990

SN - 0074-7696

VL - 225

SP - 131

EP - 185

JO - International Review of Cytology

JF - International Review of Cytology

ER -

Regulation of fish gonadotropins

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