A novel method of species identification using human muscle-specific beta-enolase

Multifunctional roles of γ-enolase in the central nervous system: more than a neuronal marker

Enolase, a multifunctional protein with diverse isoforms, has generally been recognized for its primary roles in glycolysis and gluconeogenesis. The shift in isoform expression from α-enolase to neuron-specific γ-enolase extends beyond its enzymatic role. Enolase is essential for neuronal survival, differentiation, and the maturation of neurons and glial cells in the central nervous system. Neuron-specific γ-enolase is a critical biomarker for neurodegenerative pathologies and neurological conditions, not only indicating disease but also participating in nerve cell formation and neuroprotection and exhibiting neurotrophic-like properties. These properties are precisely regulated by cysteine peptidase cathepsin X and scaffold protein γ1-syntrophin. Our findings suggest that γ-enolase, specifically its C-terminal part, may offer neuroprotective benefits against neurotoxicity seen in Alzheimer's and Parkinson's disease. Furthermore, although the therapeutic potential of γ-enolase seems promising, the effectiveness of enolase inhibitors is under debate. This paper reviews the research on the roles of γ-enolase in the central nervous system, especially in pathophysiological events and the regulation of neurodegenerative diseases.

Experimental and bioinformatic approach to identifying antigenic epitopes in human α- and β-enolases

Human α- and β-enolases are highly homologous enzymes, difficult to differentiate immunologically. In this work, we describe production, purification and properties of anti-α- and anti-β-enolase polyclonal antibodies. To raise antibodies, rabbits were injected with enolase isoenzymes that were purified from human kidney (α-enolase) and skeletal muscle (β-enolase). Selective anti-α- and anti-β-enolase antibodies were obtained by affinity chromatography on either α- or β-enolase-Sepharose columns. On Western blots, antibodies directed against human β-enolase, did not react with human α-isoenzyme, but recognized pig and rat β-enolase. To determine what makes these antibodies selective bioinformatic tools were used to predict conformational epitopes for both enolase isoenzymes. Three predicted epitopes were mapped to the same regions in both α- and β-enolase. Peptides corresponding to predicted epitopes were synthesized and tested against purified antibodies. One of the pin-attached peptides representing α-enolase epitope (the C-terminal portion of the epitope 3 - S²⁶²PDDPSRYISPDQ²⁷³) reacted with anti-α-enolase, while the other also derived from the α-enolase sequence (epitope 2 - N¹⁹³VIKEKYGKDATN²⁰⁵) was recognized by anti-β-enolase antibodies. Interestingly, neither anti-α- nor anti-β-antibody reacted with a peptide corresponding to the epitope 2 in β-enolase (G¹⁹⁴VIKAKYGKDATN²⁰⁶). Further analysis showed that substitution of E¹⁹⁷ with A in α-enolase epitope 2 peptide lead to 70% loss of immunological activity, while replacement of A¹⁹⁸ with E in peptide representing β-enolase epitope 2, caused 67% increase in immunological activity. Our results suggest that E¹⁹⁷ is essential for preserving immunologically active conformation in epitope 2 peptidic homolog, while it is not crucial for this epitope's antigenic activity in native β-enolase.

DNA microarray analysis reveals differential gene expression in the soleus muscle between male and female rats exposed to a high fat diet

It is well recognized that diet-induced dysfunctions in skeletal muscle are closely related with many metabolic diseases, such as obesity and diabetes. In the present study, we identified global changes in gender-dependent gene expressions in the soleus muscle of lean and obese rats fed a high fat diet (HFD), using DNA microarray analysis. Prior to microarray analysis, the body weight gains were found to be higher in male HFD rats than the female HFD rats. To better understand the detailed phenotypic differences in response to HFD feeding, we identified differential gene expression in soleus muscle between the genders. To this end, we extracted and summarized the genes that were up- or down-regulated more than 1.5-fold between the genders in the microarray data. As expected, a greater number of genes encoding myofibrillar proteins and glycolytic proteins were expressed higher in males than females when exposed to HFD, reflecting greater muscular activity and higher capacity for utilizing glucose as an energy fuel. However, a series of genes involved in oxidative metabolism and cellular defenses were more up-regulated in females than males. These results allowed us to conclude that compared to males, females have greater fat clearing capacity in skeletal muscle through the activation of genes encoding enzymes for fat oxidation. In conclusion, our microarray data provide a better understanding of the molecular events underlying gender dimorphism in soleus muscle, and will provide valuable information in improving gender awareness in the health care system.