Limits...
Leptin in teleost fishes: an argument for comparative study.

Copeland DL, Duff RJ, Liu Q, Prokop J, Londraville RL - Front Physiol (2011)

Bottom Line: Indeed, for animals to make favorable decisions about when to grow, eat, or reproduce, they must integrate signals among the systems responsible for energy acquisition, storage, and demand.We make the argument that leptin signaling is a likely candidate for an integrating system.Great progress has been made understanding the leptin system in mammals, however our understanding in fishes has been hampered by difficulty in cloning fish orthologs of mammalian proteins and (we assert), underutilization of the comparative approach.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Akron Akron, OH, USA.

ABSTRACT
All organisms face tradeoffs with regard to how limited energy resources should be invested. When is it most favorable to grow, to reproduce, how much lipid should be allocated to storage in preparation for a period of limited resources (e.g., winter), instead of being used for growth or maturation? These are a few of the high consequence fitness "decisions" that represent the balance between energy acquisition and allocation. Indeed, for animals to make favorable decisions about when to grow, eat, or reproduce, they must integrate signals among the systems responsible for energy acquisition, storage, and demand. We make the argument that leptin signaling is a likely candidate for an integrating system. Great progress has been made understanding the leptin system in mammals, however our understanding in fishes has been hampered by difficulty in cloning fish orthologs of mammalian proteins and (we assert), underutilization of the comparative approach.

No MeSH data available.


Multiple sequence alignment of all fish leptin sequences entered in public databases, excluding duplicate sequences. Accession numbers are listed alongside taxa in the first row of sequence. Initial alignment of amino acid sequences was performed in ClustalW with additional manual alignment informed by prior work of Gorissen et al. (2009) to identify four alpha-helices (A–D). Cysteine residues reported to form leptin’s disulfide bridge are shaded and indicated by an asterisk. Other residues with greater than 90% conservation are indicated by a plus sign.
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Figure 2: Multiple sequence alignment of all fish leptin sequences entered in public databases, excluding duplicate sequences. Accession numbers are listed alongside taxa in the first row of sequence. Initial alignment of amino acid sequences was performed in ClustalW with additional manual alignment informed by prior work of Gorissen et al. (2009) to identify four alpha-helices (A–D). Cysteine residues reported to form leptin’s disulfide bridge are shaded and indicated by an asterisk. Other residues with greater than 90% conservation are indicated by a plus sign.

Mentions: Although cloning leptin in multiple mammalian species progressed rapidly, identifying an orthologous leptin gene among ectotherms did not occur until 11 years after leptin was first identified in mice. Our group first suggested that fish express leptin by documenting a leptin-immunoreactive protein (Johnson et al., 2000), and Kurokawa first cloned leptin from Fugu via gene synteny. After Kurokawa’s seminal discovery, it was obvious why leptin was so difficult to find. Fugu leptin’s primary structure is only 13% identical to human leptin (Kurokawa et al., 2005; Figures 2 and 3). However, threading algorithms that use the carbon backbone of the human-leptin crystal structure (Zhang et al., 1997) predict that the tertiary structures of fish leptins are very similar to mammalian leptins (Kurokawa et al., 2005; Huising et al., 2006; Gorissen et al., 2009; Figure 4). One difference in fish leptin biology is its lack of expression in adipose tissue. Fish leptin mRNA is expressed primarily in liver (Takifugu, Kurokawa et al., 2005; Oryzias, Kurokawa and Murashita, 2009; Oncorhynchus, Murashita et al., 2008; Danio, Gorissen et al., 2009; Cyprinus, Huising et al., 2006), with only a single report of weak, transient leptin expression in fish adipose tissue (Pfundt et al., 2009). For most fish species, liver is the highest leptin-expressing tissue, although gonad may be highest in zebrafish (Gorissen et al., 2009).


Leptin in teleost fishes: an argument for comparative study.

Copeland DL, Duff RJ, Liu Q, Prokop J, Londraville RL - Front Physiol (2011)

Multiple sequence alignment of all fish leptin sequences entered in public databases, excluding duplicate sequences. Accession numbers are listed alongside taxa in the first row of sequence. Initial alignment of amino acid sequences was performed in ClustalW with additional manual alignment informed by prior work of Gorissen et al. (2009) to identify four alpha-helices (A–D). Cysteine residues reported to form leptin’s disulfide bridge are shaded and indicated by an asterisk. Other residues with greater than 90% conservation are indicated by a plus sign.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3117194&req=5

Figure 2: Multiple sequence alignment of all fish leptin sequences entered in public databases, excluding duplicate sequences. Accession numbers are listed alongside taxa in the first row of sequence. Initial alignment of amino acid sequences was performed in ClustalW with additional manual alignment informed by prior work of Gorissen et al. (2009) to identify four alpha-helices (A–D). Cysteine residues reported to form leptin’s disulfide bridge are shaded and indicated by an asterisk. Other residues with greater than 90% conservation are indicated by a plus sign.
Mentions: Although cloning leptin in multiple mammalian species progressed rapidly, identifying an orthologous leptin gene among ectotherms did not occur until 11 years after leptin was first identified in mice. Our group first suggested that fish express leptin by documenting a leptin-immunoreactive protein (Johnson et al., 2000), and Kurokawa first cloned leptin from Fugu via gene synteny. After Kurokawa’s seminal discovery, it was obvious why leptin was so difficult to find. Fugu leptin’s primary structure is only 13% identical to human leptin (Kurokawa et al., 2005; Figures 2 and 3). However, threading algorithms that use the carbon backbone of the human-leptin crystal structure (Zhang et al., 1997) predict that the tertiary structures of fish leptins are very similar to mammalian leptins (Kurokawa et al., 2005; Huising et al., 2006; Gorissen et al., 2009; Figure 4). One difference in fish leptin biology is its lack of expression in adipose tissue. Fish leptin mRNA is expressed primarily in liver (Takifugu, Kurokawa et al., 2005; Oryzias, Kurokawa and Murashita, 2009; Oncorhynchus, Murashita et al., 2008; Danio, Gorissen et al., 2009; Cyprinus, Huising et al., 2006), with only a single report of weak, transient leptin expression in fish adipose tissue (Pfundt et al., 2009). For most fish species, liver is the highest leptin-expressing tissue, although gonad may be highest in zebrafish (Gorissen et al., 2009).

Bottom Line: Indeed, for animals to make favorable decisions about when to grow, eat, or reproduce, they must integrate signals among the systems responsible for energy acquisition, storage, and demand.We make the argument that leptin signaling is a likely candidate for an integrating system.Great progress has been made understanding the leptin system in mammals, however our understanding in fishes has been hampered by difficulty in cloning fish orthologs of mammalian proteins and (we assert), underutilization of the comparative approach.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Akron Akron, OH, USA.

ABSTRACT
All organisms face tradeoffs with regard to how limited energy resources should be invested. When is it most favorable to grow, to reproduce, how much lipid should be allocated to storage in preparation for a period of limited resources (e.g., winter), instead of being used for growth or maturation? These are a few of the high consequence fitness "decisions" that represent the balance between energy acquisition and allocation. Indeed, for animals to make favorable decisions about when to grow, eat, or reproduce, they must integrate signals among the systems responsible for energy acquisition, storage, and demand. We make the argument that leptin signaling is a likely candidate for an integrating system. Great progress has been made understanding the leptin system in mammals, however our understanding in fishes has been hampered by difficulty in cloning fish orthologs of mammalian proteins and (we assert), underutilization of the comparative approach.

No MeSH data available.