Expression of the Brain and Muscle Isoforms of Glycogen Phosphorylase in Rat Heart

Schmid, Heide; Pfeiffer-Guglielmi, Brigitte; Dolderer, Benedikt; Thiess, Ulrike; Verleysdonk, Stephan; Hamprecht, Bernd

doi:10.1007/s11064-008-9825-3

Cited by 16 publications

(13 citation statements)

References 33 publications

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“…Compared with TA SOL has lower GP activity and increased B/M-GP immunoblotted protein. This suggests a higher content of the brain GP isoform, and as such may reflect the aerobic phenotype of the SOL muscle and its similarity to cardiac muscle, which also has a high content of the brain GP isoform (David and Crerar, 1986; Mair, 1998; Schmid et al, 2008). The lower total GP activity in SOL compared to TA may be due in part to differences between the brain and muscle isoenzyme kinetics.…”

Section: Discussionmentioning

confidence: 98%

“…The GP muscle isoform, encoded by the PYGM gene, is highly expressed in skeletal muscle in humans (Lucia et al, 2008) and rats (David and Crerar, 1986). Cardiac myocytes, in contrast, contain significant levels of the brain isoform, encoded by the PYGB gene, in both humans (Mair, 1998) and rats (David and Crerar, 1986; Schmid et al, 2008). …”

Section: Introductionmentioning

confidence: 99%

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Effects of aging and calorie restriction on rat skeletal muscle glycogen synthase and glycogen phosphorylase

Montori-Grau

Minor

Lerín

et al. 2009

Experimental Gerontology

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Calorie restriction’s (CR) effects on age-associated changes in glycogen-metabolizing enzymes were studied in rat soleus (SOL) and tibialis anterior (TA) muscles. Old (24 months) compared to young (6 months) rats maintained ad libitum on a standard diet had reduced glycogen synthase (GS) activity, lower muscle GS protein levels, increased phosphorylation of GS at site 3a with less activation in SOL. Age-associated impairments in GS protein and activation-phosphorylation were also shown in TA. There was an age-associated reduction in glycogen phosphorylase (GP) activity level in SOL, while brain/muscle isoforms (B/M) of GP protein levels were higher. GP activity and protein levels were preserved, but GP was inactivated in TA with age. Glycogen content was unchanged in both muscles. CR did not alter GS or GP activity/protein levels in young rats. CR hindered age-related decreases in GS activity/protein, unrelated to GS mRNA levels, and GS inactivation-phosphorylation; not on GP. In older rats, CR enhanced glycogen accumulation in SOL. Short-term fasting did not recapitulate CR effects in old rats. Thus, the predominant age-associated impairments on skeletal muscle GS and GP activities occur in the oxidative SOL muscle of rats, and CR can attenuate the loss of GS activity/activation and stimulate glycogen accumulation.

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Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Effects of aging and calorie restriction on rat skeletal muscle glycogen synthase and glycogen phosphorylase

Montori-Grau

Minor

Lerín

et al. 2009

Experimental Gerontology

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“…Fixation of tissue specimen for histology with EDC/NHS caused lower AF than that of GA or PFA (Robinson ; Schmid et al ., ). The results of the present study are also applicable to other methods used to assess the growth of cells on different scaffolds, such as histology and immunostaining.…”

Section: Discussionmentioning

confidence: 99%

Fluorescent imaging of endothelial cells in bioengineered blood vessels: the impact of crosslinking of the scaffold

Niu

Sapoznik

Lü

et al. 2014

J Tissue Eng Regen Med

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Fluorescent imaging is a useful tool tomonitor and evaluate bioengineered tissues and organs. However, autofluorescence emitted from the scaffold can be comparable or even overwhelm signals generated by fluorescently labelled cells and biomarkers. Using standard fluorescent microscopy techniques, a simple and easy-to-measure signal to noise ratio metric was developed, which can facilitate the selection of fluorescent biomarkers and the respective biomaterials for tissue engineering studies. Endothelial cells (MS1) expressing green-fluorescent protein and red fluorescent protein (mKate) were seeded on poly (epsilon-caprolactone)–collagen hybrid scaffolds that were prepared by crosslinking with glutaraldehyde, genipin and ethyl(dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide. All scaffolds had comparable mechanical properties, which could meet the requirements for vascular graft applications. ethyl(dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide crosslinked scaffolds had a high signal to noise ratio value because of its low autofluorescence in green and red channels. Genipin crosslinked scaffolds had a high signal to noise ratio only in the green channel, while glutaraldehyde crosslinked scaffolds had a low signal to noise ratio in both green and red channels. The signal to noise ratio was independent of the exposure time. The data show that although similar in their mechanical properties and ability to support cell growth, scaffolds crosslinked with different agents have significant differences in causing autofluorescence of the scaffolds. This result indicates that scaffold’s preparation method may have a significant impact on direct imaging of fluorescently labelled cells on scaffolds used for tissue engineering.

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“…With the exception of liver-GP, expression of the isozymes is not strictly tissue specific: muscle-GP is expressed predominantly in skeletal muscle but also, in lower concentrations, in heart muscle and brain. While the highest concentration of brain-GP is found in astrocytes, it is also expressed in heart muscle and even at very low concentrations in skeletal muscle (Schmid et al, 2009). Additionally, brain-GP is the predominant isoform in fetal tissue and only during maturation expression of the liver and muscle isoforms starts.…”

Section: Isoforms Of Glycogen Phosphorylasementioning

confidence: 99%

Brain glycogen—new perspectives on its metabolic function and regulation at the subcellular level

Obel¹,

Müller²,

Walls³

et al. 2012

Front. Neuroenerg.

178

143

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Glycogen is a complex glucose polymer found in a variety of tissues, including brain, where it is localized primarily in astrocytes. The small quantity found in brain compared to e.g., liver has led to the understanding that brain glycogen is merely used during hypoglycemia or ischemia. In this review evidence is brought forward highlighting what has been an emerging understanding in brain energy metabolism: that glycogen is more than just a convenient way to store energy for use in emergencies—it is a highly dynamic molecule with versatile implications in brain function, i.e., synaptic activity and memory formation. In line with the great spatiotemporal complexity of the brain and thereof derived focus on the basis for ensuring the availability of the right amount of energy at the right time and place, we here encourage a closer look into the molecular and subcellular mechanisms underlying glycogen metabolism. Based on (1) the compartmentation of the interconnected second messenger pathways controlling glycogen metabolism (calcium and cAMP), (2) alterations in the subcellular location of glycogen-associated enzymes and proteins induced by the metabolic status and (3) a sequential component in the intermolecular mechanisms of glycogen metabolism, we suggest that glycogen metabolism in astrocytes is compartmentalized at the subcellular level. As a consequence, the meaning and importance of conventional terms used to describe glycogen metabolism (e.g., turnover) is challenged. Overall, this review represents an overview of contemporary knowledge about brain glycogen and its metabolism and function. However, it also has a sharp focus on what we do not know, which is perhaps even more important for the future quest of uncovering the roles of glycogen in brain physiology and pathology.

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Expression of the Brain and Muscle Isoforms of Glycogen Phosphorylase in Rat Heart

Cited by 16 publications

References 33 publications

Effects of aging and calorie restriction on rat skeletal muscle glycogen synthase and glycogen phosphorylase

Effects of aging and calorie restriction on rat skeletal muscle glycogen synthase and glycogen phosphorylase

Fluorescent imaging of endothelial cells in bioengineered blood vessels: the impact of crosslinking of the scaffold

Brain glycogen—new perspectives on its metabolic function and regulation at the subcellular level

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