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Altered hypothalamic protein expression in a rat model of Huntington's disease.

Cong WN, Cai H, Wang R, Daimon CM, Maudsley S, Raber K, Canneva F, von Hörsten S, Martin B - PLoS ONE (2012)

Bottom Line: Our results demonstrate that there are significant alterations in HD rat hypothalamic protein expression such as glial fibrillary acidic protein (GFAP), heat shock protein-70, the oxidative damage protein glutathione peroxidase (Gpx4), glycogen synthase1 (Gys1) and the lipid synthesis enzyme acylglycerol-3-phosphate O-acyltransferase 1 (Agpat1).These early metabolic and lipid alterations are likely prodromal signs of hypothalamic dysfunction.Gaining a greater understanding of the hypothalamic and metabolic alterations that occur in HD, could lead to the development of novel therapeutics for early interventional treatment of HD.

View Article: PubMed Central - PubMed

Affiliation: Metabolism Unit, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America.

ABSTRACT
Huntington's disease (HD) is a neurodegenerative disorder, which is characterized by progressive motor impairment and cognitive alterations. Changes in energy metabolism, neuroendocrine function, body weight, euglycemia, appetite function, and circadian rhythm can also occur. It is likely that the locus of these alterations is the hypothalamus. We used the HD transgenic (tg) rat model bearing 51 CAG repeats, which exhibits similar HD symptomology as HD patients to investigate hypothalamic function. We conducted detailed hypothalamic proteome analyses and also measured circulating levels of various metabolic hormones and lipids in pre-symptomatic and symptomatic animals. Our results demonstrate that there are significant alterations in HD rat hypothalamic protein expression such as glial fibrillary acidic protein (GFAP), heat shock protein-70, the oxidative damage protein glutathione peroxidase (Gpx4), glycogen synthase1 (Gys1) and the lipid synthesis enzyme acylglycerol-3-phosphate O-acyltransferase 1 (Agpat1). In addition, there are significant alterations in various circulating metabolic hormones and lipids in pre-symptomatic animals including, insulin, leptin, triglycerides and HDL, before any motor or cognitive alterations are apparent. These early metabolic and lipid alterations are likely prodromal signs of hypothalamic dysfunction. Gaining a greater understanding of the hypothalamic and metabolic alterations that occur in HD, could lead to the development of novel therapeutics for early interventional treatment of HD.

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iTRAQ ratios of tgHD rat versus WT control for hypothalamus.Mean tgHD (114, 115,116) to the WT (117) isobaric mass tag ratios for samples resolved by MS/MS from the hypothalamus of both WT and tgHD rats. Proteins identified from peptides that displayed a ratio greater than or equal to 1.2 or less that or equal to 0.8 are considered to be statistically different according to standard protocols from unity and therefore distinctly regulated compared to WT.
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pone-0047240-g006: iTRAQ ratios of tgHD rat versus WT control for hypothalamus.Mean tgHD (114, 115,116) to the WT (117) isobaric mass tag ratios for samples resolved by MS/MS from the hypothalamus of both WT and tgHD rats. Proteins identified from peptides that displayed a ratio greater than or equal to 1.2 or less that or equal to 0.8 are considered to be statistically different according to standard protocols from unity and therefore distinctly regulated compared to WT.

Mentions: iTRAQ mass tag ratios were calculated for proteins with reliable identifications (see Materials and Methods) based upon their collision-induced dissociation fragmentation patterns. Ratios of the tgHD mass tags (114, 115, 116) compared to the WT tags (117) that were greater than 1.2 or less than 0.8 were considered to be statistically different, i.e. altered expression level of the protein. Two representative iTRAQ mass spectrometry peptide identifications (glial fibrillary acidic protein (GFAP) and Lamin A) are demonstrated in Figs. 4 and 5. In total, we identified 395 significantly altered proteins in the hypothalamus of the tgHD rats (compared to the WT), which included 84 up-regulated proteins and 311 down-regulated proteins (Fig. 6, Table S2). To verify the expression changes of the identified proteins, western blots were performed by resolving tissue lysate samples onto PVDF membranes (Fig. 7). Seven proteins that were identified as significantly altered proteins by iTRAQ mass spectrometry were selected for western blot analysis. Among these proteins, G1 to S phase transition 2 (Gspt2), phosphatidylethanolamine binding protein 1 (Pebp1), muscle pyruvate kinase (Pkm2) and mTOR were up-regulated in the hypothalamus and GFAP, flotillin-2 (Flot2), and Lamin A were down-regulated in the hypothalamus of tgHD rats. Westen blotting of these proteins revealed differential protein expression, consistent with the iTRAQ results.


Altered hypothalamic protein expression in a rat model of Huntington's disease.

Cong WN, Cai H, Wang R, Daimon CM, Maudsley S, Raber K, Canneva F, von Hörsten S, Martin B - PLoS ONE (2012)

iTRAQ ratios of tgHD rat versus WT control for hypothalamus.Mean tgHD (114, 115,116) to the WT (117) isobaric mass tag ratios for samples resolved by MS/MS from the hypothalamus of both WT and tgHD rats. Proteins identified from peptides that displayed a ratio greater than or equal to 1.2 or less that or equal to 0.8 are considered to be statistically different according to standard protocols from unity and therefore distinctly regulated compared to WT.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3475691&req=5

pone-0047240-g006: iTRAQ ratios of tgHD rat versus WT control for hypothalamus.Mean tgHD (114, 115,116) to the WT (117) isobaric mass tag ratios for samples resolved by MS/MS from the hypothalamus of both WT and tgHD rats. Proteins identified from peptides that displayed a ratio greater than or equal to 1.2 or less that or equal to 0.8 are considered to be statistically different according to standard protocols from unity and therefore distinctly regulated compared to WT.
Mentions: iTRAQ mass tag ratios were calculated for proteins with reliable identifications (see Materials and Methods) based upon their collision-induced dissociation fragmentation patterns. Ratios of the tgHD mass tags (114, 115, 116) compared to the WT tags (117) that were greater than 1.2 or less than 0.8 were considered to be statistically different, i.e. altered expression level of the protein. Two representative iTRAQ mass spectrometry peptide identifications (glial fibrillary acidic protein (GFAP) and Lamin A) are demonstrated in Figs. 4 and 5. In total, we identified 395 significantly altered proteins in the hypothalamus of the tgHD rats (compared to the WT), which included 84 up-regulated proteins and 311 down-regulated proteins (Fig. 6, Table S2). To verify the expression changes of the identified proteins, western blots were performed by resolving tissue lysate samples onto PVDF membranes (Fig. 7). Seven proteins that were identified as significantly altered proteins by iTRAQ mass spectrometry were selected for western blot analysis. Among these proteins, G1 to S phase transition 2 (Gspt2), phosphatidylethanolamine binding protein 1 (Pebp1), muscle pyruvate kinase (Pkm2) and mTOR were up-regulated in the hypothalamus and GFAP, flotillin-2 (Flot2), and Lamin A were down-regulated in the hypothalamus of tgHD rats. Westen blotting of these proteins revealed differential protein expression, consistent with the iTRAQ results.

Bottom Line: Our results demonstrate that there are significant alterations in HD rat hypothalamic protein expression such as glial fibrillary acidic protein (GFAP), heat shock protein-70, the oxidative damage protein glutathione peroxidase (Gpx4), glycogen synthase1 (Gys1) and the lipid synthesis enzyme acylglycerol-3-phosphate O-acyltransferase 1 (Agpat1).These early metabolic and lipid alterations are likely prodromal signs of hypothalamic dysfunction.Gaining a greater understanding of the hypothalamic and metabolic alterations that occur in HD, could lead to the development of novel therapeutics for early interventional treatment of HD.

View Article: PubMed Central - PubMed

Affiliation: Metabolism Unit, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America.

ABSTRACT
Huntington's disease (HD) is a neurodegenerative disorder, which is characterized by progressive motor impairment and cognitive alterations. Changes in energy metabolism, neuroendocrine function, body weight, euglycemia, appetite function, and circadian rhythm can also occur. It is likely that the locus of these alterations is the hypothalamus. We used the HD transgenic (tg) rat model bearing 51 CAG repeats, which exhibits similar HD symptomology as HD patients to investigate hypothalamic function. We conducted detailed hypothalamic proteome analyses and also measured circulating levels of various metabolic hormones and lipids in pre-symptomatic and symptomatic animals. Our results demonstrate that there are significant alterations in HD rat hypothalamic protein expression such as glial fibrillary acidic protein (GFAP), heat shock protein-70, the oxidative damage protein glutathione peroxidase (Gpx4), glycogen synthase1 (Gys1) and the lipid synthesis enzyme acylglycerol-3-phosphate O-acyltransferase 1 (Agpat1). In addition, there are significant alterations in various circulating metabolic hormones and lipids in pre-symptomatic animals including, insulin, leptin, triglycerides and HDL, before any motor or cognitive alterations are apparent. These early metabolic and lipid alterations are likely prodromal signs of hypothalamic dysfunction. Gaining a greater understanding of the hypothalamic and metabolic alterations that occur in HD, could lead to the development of novel therapeutics for early interventional treatment of HD.

Show MeSH
Related in: MedlinePlus