Identification of a Novel Metabolic Target for Bioactive Triterpenoids Biosynthesis in Ganoderma lucidum.

Triterpenoids are crucial active ingredients of Ganoderma lucidum (G. lucidum) with various health benefits. Yet the low biosynthesis greatly restricts their industrial applications, novel metabolic engineering strategies are needed to further enhance Ganoderma triterpenoids production. Transcription factors play vital roles in the metabolic regulation of terpenoids, which are still scarce to study in G. lucidum. Herein, a transcription factor GlbHLH5 (GenBank No. MZ436906.1) potential for metabolic regulation of Ganoderma triterpenes was identified for the first time. MeJA could increase Ganoderma triterpenoids biosynthesis, and GlbHLH5 significantly responded to MeJA induction, suggesting GlbHLH5 is a new target for Ganoderma triterpenoids overproduction. The regulatory effect of the newly identified target was further validated by homologous gene overexpression and silence in G. lucidum. It's demonstrated that overexpression of GlbHLH5 significantly increased triterpenoids accumulation and the key enzyme genes transcription in the biosynthetic pathway, while silencing it displayed the opposite effect, indicating GlbHLH5 could positively regulate the triterpenoids biosynthesis by activating the synergistic expression of key enzyme genes in the biosynthetic pathway. Consequently, GlbHLH5 was identified as a positive regulator and novel metabolic target for Ganoderma triterpenoids biosynthesis, it sheds new lights on the regulatory effect regulation and synthetic biology of Ganoderma triterpenoids.

Effects of ganoderma triterpenoids combined with exogenous GM1 on cognitive function and hippocampal synaptic structure in rats with epilepsy / 中华行为医学与脑科学杂志

Objective:To study the intervention effect of ganoderma triterpenoids combined with exogenous monosialotetrahexosyl ganglioside(GM1) on cognitive dysfunction and synaptic ultrastructure of hippocampal neurons in rats with epilepsy caused by pentylenetetrazol(PTZ).Methods:A total of 40 Sprague-Dawley rats were divided into blank control group, epileptic model group, ganoderma triterpenoids group, GM1 group and GM1 combined with ganoderma triterpenoids group according to the random number table method( n=8 in each group). The rats were intraperitoneally injected with PTZ subconvulsant dose (35 mg·kg -1·d -1) once a day for 28 days to replicate the models of chronic epilepsy. And the rats in different medication groups were given corresponding administration based on daily intraperitoneal injection of PTZ(GM1: intraperitoneal injection of 30 mg·kg -1·d -1, ganoderma triterpenoids: gavage 1 000 mg·kg -1·d -1). Morris water maze was used to test the spatial exploration and learning and memory ability of epileptic rats.Transmission electron microscopy was used to observe the ultrastructure of hippocampal neurons in epileptic rats.Immunofluorescence staining was used to observe expression levels of cofilin and SYN protein in hippocampus CA1 of rats. In addition, Western blot was used to detect the expression levels of cofilin, p-cofilin and synaptophysin(SYN) protein in hippocampus of rats. SPSS 17.0 software was used for statistical analysis. Repeated one-way ANOVA was used for comparing among groups, LSD test was used for pairwise comparisons. Results:Morris water maze results showed that there were statistically significant differences in escape latency, times of crossing the platform and time spent in the target quadrant among the groups( F=5.259, 8.240, 5.961, all P<0.05). Compared with the epilepsy model group, the escape latencies((20.31±7.39) s, (21.81±6.05) s, (17.66±4.76) s) of the ganoderma triterpenoids group, GM1 group and GM1 combined with ganoderma triterpenoids group were shorter (all P<0.05), the numbers of crossing the platform ((4.63±1.41) times, (4.50±1.93) times, (5.50±1.77) times) were more (all P<0.05), the residence time in target quadrant ((31.91±5.00) s, (30.49±5.72) s, (35.70±5.34) s) were longer (all P<0.05). And the most obvious change was found in the GM1 combined with ganoderma triterpenoids group ( P<0.01). The results of transmission electron microscope showed that there were significant differences in the numbers of hippocampal neurons synapses, the synaptic gap, the density of postsynaptic membrane and length of active area of postsynaptic membrane among the groups( F=3.693, 7.201, 5.012, 4.033, all P<0.05). Compared with the epilepsy model group, the numbers of synapses ((8.00±1.79), (7.83±1.84), (8.50±1.87)) in the ganoderma triterpenoids group, GM1 group and GM1 combined with ganoderma triterpenoids group were all more (all P<0.05), synaptic gap ((33.83±3.81)nm, (32.43±4.14)nm, (30.23±3.08)nm)were narrower, and the postsynaptic dense substances ((57.50±6.03)nm, (58.10±2.40)nm, (60.73±3.81)nm) were all thicker (all P<0.05). The length of active region of postsynaptic membrane ((271.66±11.80) nm, (279.06±13.58) nm) in ganoderma triterpenoid group and GM1 combined with ganoderma triterpenoids group were longer than that in epilepsy model group (both P<0.05). Immunofluorescence results showed that the average fluorescence intensity of cofilin in the epilepsy model group was higher than that in the blank control group, and the average fluorescence intensity of SYN was lower than that in the blank control group (both P<0.05). The average fluorescence intensity of cofilin in GM1 group and GM1 combined with ganoderma triterpenoids group were lower than that in epilepsy model group (both P<0.05), and the average fluorescence intensity of SYN in ganoderma lucidum triterpenoids combined with GM1 group was higher than that in epilepsy model group ( P<0.05). Western blot showed that the expression levels of cofilin protein in the epilepsy model group was higher than that in the blank control group ((1.454±0.080), (1.092±0.099), P<0.05), and the expression of p-cofilin and SYN were lower than those in the blank control group ((1.103±0.120) vs (1.420±0.934), (1.650±0.062) vs (1.958±0.062), both P<0.05). The expression of cofilin protein ((1.227±0.071), (1.262±0.078), (1.162±0.129), P<0.05) in ganoderma triterpenoids group, GM1 group and GM1 combined with ganoderma triterpenoids group were lower than that in epilepsy model group, and the expression levels of p-cofilin(1.357±0.199) and SYN protein(1.873±0.010) in ganoderma triterpenoids combined with GM1 group were higher than that in epilepsy model group (both P<0.05). Compared with ganoderma lucidum triterpenoids group and GM1 group, there was no significant difference in each index of GM1 combined with ganoderma triterpenoids group (all P>0.05). Conclusion:GM1 combined with ganoderma triterpenoids may promote the synaptic plasticity of neurons, improve the learning and memory ability of epileptic rats.Combination medication is better than single medication in some observed indicators.

Evidence for Effective Inhibitory Actions on Hyperpolarization-Activated Cation Current Caused by Ganoderma Triterpenoids, the Main Active Constitutents of Ganoderma Spores.

The triterpenoid fraction of Ganoderma (Ganoderma triterpenoids, GTs) has been increasingly demonstrated to provide effective antioxidant, neuroprotective or cardioprotective activities. However, whether GTs is capable of perturbing the transmembrane ionic currents existing in electrically excitable cells is not thoroughly investigated. In this study, an attempt was made to study whether GTs could modify hyperpolarization-activated cation currents (Ih) in pituitary tumor (GH3) cells and in HL-1 atrial cardiomyocytes. In whole-cell current recordings, the addition of GTs produced a dose-dependent reduction in the amplitude of Ih in GH3 cells with an IC50 value of 11.7 µg/mL, in combination with a lengthening in activation time constant of the current. GTs (10 µg/mL) also caused a conceivable shift in the steady-state activation curve of Ih along the voltage axis to a more negative potential by approximately 11 mV. Subsequent addition of neither 8-cyclopentyl-1,3-dipropylxanthine nor 8-(p-sulfophenyl)theophylline, still in the presence of GTs, could attenuate GTs-mediated inhibition of Ih. In current-clamp voltage recordings, GTs diminished the firing frequency of spontaneous action potentials in GH3 cells, and it also decreased the amplitude of sag potential in response to hyperpolarizing current stimuli. In murine HL-1 cardiomyocytes, the GTs addition also suppressed the amplitude of Ih effectively. In DPCPX (1 µM)-treated HL-1 cells, the inhibitory effect of GTs on Ih remained efficacious. Collectively, the inhibition of Ih caused by GTs is independent of its possible binding to adenosine receptors and it might have profound influence in electrical behaviors of different types of electrically excitable cells (e.g., pituitary and heart cells) if similar in vitro or in vivo findings occur.

Protective effects of Ganoderma triterpenoids on cadmium-induced oxidative stress and inflammatory injury in chicken livers.

Several studies have been conducted on liver damage caused by cadmium, but few on the protective effects of Ganoderma triterpenoids against liver damage due to cadmium. This experiment was designed to evaluate the protective effects of Ganoderma triterpenoids on the liver damage induced by cadmium in chickens. Eighty healthy seven-day-old Hyline male egg-laying chickens were randomly divided into four groups with 20 chickens in each group. All the experiments were carried out in triplicate. The control group (K group) was fed a basal diet, the Cadmium group (Cd group) was fed a basal diet with 140 mg/kg of CdCl2, the Ganoderma triterpenoids treatment group (Cd + GT group) was fed with a full-fodder diet containing 140 mg/kg of CdCl2 and 0.5 mL of Ganoderma triterpenoids solution (20 mg/mL), and the Ganoderma triterpenoids group (GT group) was fed a basal diet and 0.5 mL of Ganoderma triterpenoids solution (20 mg/mL). At the 20th, 40th, and 60th days, fifteen chickens were randomly selected for euthanasia in each group. Livers were quickly removed and stored on ice. Some indicators, such as the cadmium content in the liver, antioxidant enzymes (superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px)) activities, malondialdehyde (MDA) content, and inflammatory factors(Tumor necrosis factor alpha (TNF-α), interleukin (IL-1ß and IL-6)), heat shock protein (HSP27, 40, 60, 70, and 90) mRNA levels, and protein levels of heat shock proteins (HSP60, 70, and 90) were detected, and chicken liver pathology was taken for each group every 60 days. The results showed that cadmium exposure caused accumulation of cadmium in liver tissue, inhibited antioxidant enzyme activity, and increased MDA content, inflammatory cytokines (TNF-α IL-1ß and IL-6), and heat shock protein (HSP27, 40, 60, 70, and 90) mRNA levels, and heat shock protein (HSP60, 70, and 90) levels, with severe tissue damage and inflammatory infiltrates. Ganoderma triterpenoids not only reduced the accumulation of cadmium in the chicken liver, but also significantly increased the activities of antioxidant enzymes which is inhibited by cadmium, reduced the content of MDA, mRNA expressions of inflammatory cytokines (TNF-α IL-1ß and IL-6), and heat shock proteins (HSP27, 40, 60, 70, and 90), and protein levels of heat shock proteins (HSP60, 70, and 90). Simultaneously, pathological tissue sections showed that the pathological damage of the liver tissue was significantly reduced. The results showed that Ganoderma triterpenoids can significantly reduce the accumulation of cadmium in the liver of chicken, thereby reducing oxidative stress and inflammation.

Protective Effect of Ganoderma Triterpenoids on Cadmium-Induced Testicular Toxicity in Chickens.

Studies have shown that cadmium can cause chicken testicular damage, but a protective effect of Ganoderma triterpenoids on cadmium-induced testicular damage in chickens has not yet been reported. The present study was designed to research the protective effect of Ganoderma triterpenoids on cadmium-induced testicular damage in chicken. Eighty healthy 7-day-old Hyline egg laying chickens were randomly divided into four groups with 20 in each group. The control group was fed with normal full-fodder, the model group was fed with normal full-fodder with 140 mg/kg of CdCl2, the Ganoderma triterpenoid treatment group was fed with a full-fodder diet containing 140 mg/kg of CdCl2 and 0.5 mL of Ganoderma triterpenoid solution (20 mg/mL), and the Ganoderma triterpenoid group was fed normal full-fodder and 0.5 mL of Ganoderma triterpenoid solution (20 mg/mL) gavage. The chickens were euthanized at 20, 40, and 60 days, respectively, and the testes were harvested. The changes of cadmium contents, the antioxidant enzymes (superoxide dismutase (SOD), glutathione peroxidase (GSH-Px)), peroxide (malondialdehyde (MDA)), inflammatory factors (interleukin (IL)-1ß, IL-6, and tumor necrosis factor alpha (TNF-α)), and apoptosis-related proteins (Bax, Bcl-2, and Caspase-3) were detected. The pathological sections of the testes were made at the same time. The results suggested that Ganoderma triterpenoids could reduce the accumulation of cadmium in testis tissue; reduce the content of IL-1ß, IL-6, and TNF-α in cadmium poisoning testis; significantly increase the activity of SOD and GSH-Px; decrease the content of MDA; regulate the expression of Bax, Caspase-3, and Bcl-2; and reduce the damage of testicular tissue. The results showed that Ganoderma triterpenoids have a protective effect on cadmium-induced testicular injury in chicken.