Growth hormone and insulin-like growth factor I of a Euryhaline fish Cottus kazika: cDNA cloning and expression after seawater acclimation

Inoue, Koji; Iwatani, Hozi; Takei, Yoshiyuki

doi:10.1016/s0016-6480(02)00650-0

Cited by 35 publications

(30 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These findings imply that the possibility of IGF cross-talk with insulin receptor in the carp pituitary is unlikely. Although the liver represents a major source of IGF in circulation, IGF-I and -II are also known to be produced locally in the pituitary of fish models, including tilapia (9) and Cottus kazika (18). In our study, the inhibitors for IGF-IR activation alone without IGF cotreatment were also effective in reducing basal levels of SL␣ and SL␤ secretion, cell content, and mRNA expression.…”

Section: Discussionmentioning

confidence: 54%

Insulin-like growth factor as a novel stimulator for somatolactin secretion and synthesis in carp pituitary cells via activation of MAPK cascades

Jiang

Wong

2011

American Journal of Physiology-Endocrinology and Metabolism

View full text Add to dashboard Cite

Jiang Q, Ko WK, Wong AO. Insulin-like growth factor as a novel stimulator for somatolactin secretion and synthesis in carp pituitary cells via activation of MAPK cascades. Am J Physiol Endocrinol Metab 301: E1208 -E1219, 2011. First published August 23, 2011; doi:10.1152/ajpendo.00347.2011, a member of the growth hormone/prolactin family, is a pituitary hormone unique to fish models. Although SL is known to have diverse functions in fish, the mechanisms regulating its secretion and synthesis have not been fully characterized. Using grass carp pituitary cells as a model, here we examined the role of insulin-like growth factor (IGF) in SL regulation at the pituitary level. As a first step, the antisera for the two SL isoforms expressed in the carp pituitary, SL␣ and SL␤, were produced, and their specificity was confirmed by antiserum preabsorption and immunohistochemical staining in the carp pituitary. Western blot using these antisera revealed that grass carp SL␣ and SL␤ could be N-linked glycosylated and their basal secretion and cell content in carp pituitary cells could be elevated by IGF-I and -II treatment. These stimulatory effects occurred with parallel rises in SL␣ and SL␤ mRNA levels, and these SL gene expression responses were not mimicked by insulin but blocked by IGF-I receptor inactivation. In carp pituitary cells, IGF-I and -II could induce rapid phosphorylation of IGF-I receptor, MEK1/2, ERK1/2, MKK3/6, and p38 MAPK; and SL␣ and SL␤ secretion, protein production, and mRNA expression caused by IGF-I and -II stimulation were negated by inactivating MEK1/2 and p38 MAPK. Parallel inhibition of PI3K and Akt, however, were not effective in these regards. These results, taken together, provide evidence that IGF can upregulate SL secretion and synthesis at the pituitary level via stimulation of MAPK-but not PI3K/Akt-dependent pathways.insulin-like growth factor I receptor; mitogen-activated protein kinase; signal transduction; grass carp SOMATOLACTIN (SL), a member of the growth hormone (GH)/ prolactin (PRL) family, is a pituitary hormone unique to fish models (23). Since SL gene could not be identified in the genome databases of tetrapods, including Xenopus, mouse, and human, it is commonly accepted that the gene had been lost in tetrapods during the land invasion of amphibian ancestors (15). To date, two SL isoforms, SL␣ and SL␤, have been reported in bony fish, including zebrafish (53) and grass carp (Ctenopharyngodon idellus) (20). Unlike GH and PRL with expression restricted to pituitary cells in the pars distalis, SL is expressed in periodic acid-Schiff (PAS)-positive cells located in the neurointermediate lobe (NIL) of the fish pituitary (34). PAS staining is commonly used in polysaccharide and glycoprotein detection in biological samples. The sensitivity of SL cells to PAS staining and the presence of N-linked glycosylation sites on SL itself [e.g., in Atlantic cod (39) and carp SL (20)] suggest that SL is a glycoprotein. This idea is supported by the finding that a glycosylated form of SL␣ sensit...

show abstract

Section: Discussionmentioning

confidence: 54%

Insulin-like growth factor as a novel stimulator for somatolactin secretion and synthesis in carp pituitary cells via activation of MAPK cascades

Jiang

Wong

2011

American Journal of Physiology-Endocrinology and Metabolism

View full text Add to dashboard Cite

show abstract

“…In tilapia, the importance of local IGF-I expression is stressed by its very early appearance in chloride cells around 6-7 DPF (Berishvili et al 2006a). In several fish species, evidence has been presented that both circulating (liver-derived) IGF-I (Madsen & Bern 1993, Shepherd et al 1997, Inoue et al 2003 and autocrine/ paracrine IGF-I from the chloride cells (Sakamoto & Hirano 1993, Biga et al 2004) mediate the osmoregulatory actions of GH. Previous studies have reported that E 2 impairs osmoregulation in salmonid (Arsenault et al 2004, Madsen et al 2004, McCormick et al 2005) and non-salmonid (Vijayan et al 2001) fish, and suppressed plasma levels of Figure 7 Influence of EE 2 exposure on GH and ERa mRNA levels in tilapia pituitary revealed by real-time PCR.…”

Section: Discussionmentioning

confidence: 99%

Ethinylestradiol differentially interferes with IGF-I in liver and extrahepatic sites during development of male and female bony fish

Shved

Berishvili

D'Cotta

et al. 2007

Journal of Endocrinology

View full text Add to dashboard Cite

Growth and sexual development are closely interlinked in fish; however, no reports exist on potential effects of estrogen on the GH/IGF-I-axis in developing fish. We investigate whether estrogen exposure during early development affects growth and the IGF-I system, both at the systemic and tissue level. Tilapia were fed from 10 to 40 days post fertilization (DPF) with 17a-ethinylestradiol (EE 2 ). At 50, 75, 90, and 165 DPF, length, weight, sex ratio, serum IGF-I (RIA), pituitary GH mRNA and IGF-I, and estrogen receptor a (ERa) mRNA in liver, gonads, brain, and gills (real-time PCR) were determined and the results correlated to those of in situ hybridization for IGF-I. Developmental exposure to EE 2 had persistent effects on sex ratio and growth. Serum IGF-I, hepatic IGF-I mRNA, and the number of IGF-I mRNA-containing hepatocytes were significantly decreased at 75 DPF, while liver ERa mRNA was significantly induced. At 75 DPF, a transient decline of IGF-I mRNA and a largely reduced number of IGF-I mRNA-containing neurons were observed in the female brain. In both sexes, pituitary GH mRNA was significantly suppressed. A transient downregulation of IGF-I mRNA occurred in ovaries (75 DPF) and testes (90 DPF). In agreement, in situ hybridization revealed less IGF-I mRNA signals in granulosa and germ cells. Our results show for the first time that developmental estrogen treatment impairs GH/IGF-I expression in fish, and that the effects persist. These long-lasting effects both seem to be exerted indirectly via inhibition of pituitary GH and directly by suppression of local IGF-I in organ-specific cells.

show abstract

“…Transfer to seawater is associated with an increase in plasma concentrations of GH in salmonids (657), as well as increased message for IGF-I in the gills of coho salmon (656). The gene for IGF-I and its product can be localized to MRC in the tilapia gills (641), and an IGF-I receptor has been cloned and localized to the gills in two sculpins (317,412). It is generally considered that IGF-I is the direct mediator of increased Na ϩ -K ϩ -ATPase activity in the MRCs but that GH is needed for the response (e.g., Ref.…”

Section: Growth Hormone and Igfmentioning

confidence: 99%

The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste

Evans¹,

Piermarini²,

Choe³

2005

Physiological Reviews

2,299

1,788

View full text Add to dashboard Cite

The fish gill is a multipurpose organ that, in addition to providing for aquatic gas exchange, plays dominant roles in osmotic and ionic regulation, acid-base regulation, and excretion of nitrogenous wastes. Thus, despite the fact that all fish groups have functional kidneys, the gill epithelium is the site of many processes that are mediated by renal epithelia in terrestrial vertebrates. Indeed, many of the pathways that mediate these processes in mammalian renal epithelial are expressed in the gill, and many of the extrinsic and intrinsic modulators of these processes are also found in fish endocrine tissues and the gill itself. The basic patterns of gill physiology were outlined over a half century ago, but modern immunological and molecular techniques are bringing new insights into this complicated system. Nevertheless, substantial questions about the evolution of these mechanisms and control remain.

show abstract

Growth hormone and insulin-like growth factor I of a Euryhaline fish Cottus kazika: cDNA cloning and expression after seawater acclimation

Cited by 35 publications

References 29 publications

Insulin-like growth factor as a novel stimulator for somatolactin secretion and synthesis in carp pituitary cells via activation of MAPK cascades

Insulin-like growth factor as a novel stimulator for somatolactin secretion and synthesis in carp pituitary cells via activation of MAPK cascades

Ethinylestradiol differentially interferes with IGF-I in liver and extrahepatic sites during development of male and female bony fish

The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste

Contact Info

Product

Resources

About