Copper metabolism in Saccharomyces cerevisiae: an update.

Copper is an essential element in all forms of life. It acts as a cofactor of some enzymes and is involved in forming proper protein conformations. However, excess copper ions in cells are detrimental as they can generate free radicals or disrupt protein structures. Therefore, all life forms have evolved conserved and exquisite copper metabolic systems to maintain copper homeostasis. The yeast Saccharomyces cerevisiae has been widely used to investigate copper metabolism as it is convenient for this purpose. In this review, we summarize the mechanism of copper metabolism in Saccharomyces cerevisiae according to the latest literature. In brief, bioavailable copper ions are incorporated into yeast cells mainly via the high-affinity transporters Ctr1 and Ctr3. Then, intracellular Cu+ ions are delivered to different organelles or cuproproteins by different chaperones, including Ccs1, Atx1, and Cox17. Excess copper ions bind to glutathione (GSH), metallothioneins, and copper complexes are sequestered into vacuoles to avoid toxicity. Copper-sensing transcription factors Ace1 and Mac1 regulate the expression of genes involved in copper detoxification and uptake/mobilization in response to changes in intracellular copper levels. Though numerous recent breakthroughs in understanding yeast's copper metabolism have been achieved, some issues remain unresolved. Completely elucidating the mechanism of copper metabolism in yeast helps decode the corresponding system in humans and understand how copper-related diseases develop.

The molecular mechanisms of copper metabolism and its roles in human diseases.

Copper is an essential element in cells; it can act as either a recipient or a donor of electrons, participating in various reactions. However, an excess of copper ions in cells is detrimental as these copper ions can generate free radicals and increase oxidative stress. In multicellular organisms, copper metabolism involves uptake, distribution, sequestration, and excretion, at both the cellular and systemic levels. Mammalian enterocytes take in bioavailable copper ions from the diet in a Ctr1-dependent manner. After incorporation, cuprous ions are delivered to ATP7A, which pumps Cu+ from enterocytes into the blood. Copper ions arrive at the liver through the portal vein and are incorporated into hepatocytes by Ctr1. Then, Cu+ can be secreted into the bile or the blood via the Atox1/ATP7B/ceruloplasmin route. In the bloodstream, this micronutrient can reach peripheral tissues and is again incorporated by Ctr1. In peripheral tissue cells, cuprous ions are either sequestrated by molecules such as metallothioneins or targeted to utilization pathways by chaperons such as Atox1, Cox17, and CCS. Copper metabolism must be tightly controlled in order to achieve homeostasis and avoid disorders. A hereditary or acquired copper unbalance, including deficiency, overload, or misdistribution, may cause or aggravate certain diseases such as Menkes disease, Wilson disease, neurodegenerative diseases, anemia, metabolic syndrome, cardiovascular diseases, and cancer. A full understanding of copper metabolism and its roles in diseases underlies the identification of novel effective therapies for such diseases.

A double dealing tale of p63: an oncogene or a tumor suppressor.

As a member of tumor suppressor p53 family, p63, a gene encoding versatile protein variant, has been documented to correlate with cancer formation and progression, though it is rarely mutated in cancer patients. However, it has long been controversial on whether p63 is an oncogene or a tumor suppressor. Here, we comprehensively reviewed reports on roles of p63 in development, tumorigenesis and tumor progression. According to data from molecular cell biology, genetic models and clinic research, we conclude that p63 may act as either an oncogene or a tumor suppressor gene in different scenarios: TA isoforms of p63 gene are generally tumor-suppressive through repressing cell proliferation, survival and metastasis; ΔN isoforms, however, may initiate tumorigenesis via promoting cell proliferation and survival, but inhibit tumor metastasis and progression; effects of p63 on tumor formation and progression depend on the context of the whole p53 family, and either amplification or loss of p63 gene locus can break the balance to cause tumorigenesis.

[Effect of PI3K/AKT inhibitor on benign prostate hyperplasia and its mechanism: an experimental study].

OBJECTIVE: To explore the effect of the phosphoinositide 3-kinase/protein kinase B (PI3K/PKB or PI3K/AKT) signaling pathway inhibitor on benign prostate hyperplasia (BPH) and its mechanism. METHODS: Forty-eight SD male adult rats aged 12 weeks were equally randomized to 4 groups: sham operation control, BPH model, 50 mg LY294002 and 100 mg LY294002. The BPH models were made by muscular injection of testosterone propionate at 10 mg/kg/d for 30 days following castration. The LY294002 groups were treated with the PI3K/AKT signaling pathway inhibitor LY294002 at 50 and 100 mg/kg every other day for 30 days. The prostates of the rats were weighed and the structural changes of the prostatic histiocytes observed under the light microscope. The expressions of Ki-67, anti-apoptotic Bcl-2 and apoptotic Bax were detected by immunohistochemistry, and the apoptosis of prostatic cells determined by terminal de-oxynucleotidyl transferase-mediated dUTP nick end labeling. RESULTS: The prostate wet weight and prostatic index were (551 +/- 10.8) mg and 1.61 +/- 0.05 in the sham operation group, (687 +/- 13.8) mg and 2.15 +/- 0.12 in the BPH model group, (623 +/- 23.5) mg and 1.95 +/- 0.11 in the LY294002 50 mg group (P < 0.05 versus the BPH models) and (561 +/- 12.6) mg and 1.71 +/- 0.18 in the LY294002 100 mg group (P < 0.01 versus the BPH models). The expressions of apoptotic Bax and anti-apoptotic Bcl-2 were 16.7% and 16.7% in the sham operation group, 16.7% and 58.3% in the BPH model group, 33.3% and 33.3% in the LY294002 50 mg group (P < 0.05 versus the BPH models), and 50.0% and 25.0% in the LY294002 100 mg group (P < 0.01 versus the BPH models). The proliferative and apoptotic indexes were 14.2 +/- 6.4 and 6.5 +/- 1.8 in the epithelial and 7.6 +/- 2.6 and 2.5 +/- 0.3 in the interstitial tissue of the sham operation group, 50.9 +/- 12.8 and 2.7 +/- 1.4 in the epithelial and 16.5 +/- 5.7 and 1.3 +/- 0.8 in the interstitial tissue of the BPH models, 32.0 +/- 13.8 and 6.2 +/- 2.5 in the epithelial and 12.1 +/- 3.8 and 1.6 +/- 1.1 in the interstitial tissue of the LY294002 50 mg group (P < 0.05 versus the BPH models), and 17.8 +/- 14.7 and 7.4 +/- 3.6 in the epithelial and 9.5 +/- 3.4 and 2.2 +/- 1.3 in the interstitial tissue of the LY294002 100 mg group (P < 0.01 versus the BPH models). CONCLUSION: The increased proliferation and decreased apoptosis of prostatic cells in the BPH animal models might be involved in the development and progression of BPH. The PI3K/AKT signaling pathway plays an important role in the development of BPH, which could be inhibited by blocking the PI3K/AKT signaling pathway.

Nanoparticle-Encapsulated Liushenwan Could Treat Nanodiethylnitrosamine-Induced Liver Cancer in Mice by Interfering With Multiple Critical Factors for the Tumor Microenvironment.

We previously isolated an ethanol fraction of LSW (Liushenwan pill, a traditional Chinese medicine) which has been shown to prevent and treat liver cancer induced by nanodiethylnitrosamine (nanoDEN) in mice. In the present study, we utilized a high-pressure microfluidics technique to generate LSW lipid nanoparticles (nano-LSW) to reduce its toxicity, and enhance its inhibitory effect on tumor growth, and further evaluate its therapeutic effect using a nanoDEN-induced mouse model of liver cancer. Our in vitro results indicated that nano-LSW-low could induce apoptosis in HepG2 cells, but exhibited low toxicity in L02 cells. Furthermore, the in vivo results indicated that nano-LSW-low exerted minimal or no damage to normal hepatocytes, kidney, and small intestine tissues. In addition, our results showed that at the 20th week, the inflammatory infiltration in the mice in the model group increased severely, and partial pimelosis and fibrosis occurred. In contrast, the liver tissues in the mice treated with nano-LSW exhibited only slight inflammatory infiltration, without pimelosis and fibrosis. At the 30th week, 4 out of 5 liver tissues in the model group showed hyperplastic nodules by hematoxylin and eosin (H&E) staining. However, the liver tissues in the nano-LSW treatment group did not showed hyperplastic nodules. Immunohistochemical staining showed that, in contrast to the model group, the levels of COX-2, PCNA, ß-catenin, and HMGB1 protein expressions were significantly lower in the nano-LSW-low group at the 20th and 30th week. Compared to model group, the COX-2, TNF-α, Smad-2, and TGF-ß1 mRNA levels obviously decreased in the liver tissue after the nano-LSW-low treatment. Taken together, nano-LSW-low may serve as a potent therapeutic agent for preventing liver cancer by interfering with multiple critical factors for the tumor microenvironment during oncogenesis.

Cullin3/KCTD5 induces monoubiquitination of ΔNp63α and impairs its activity.

Potassium channel tetramerization domain containing 5 (KCTD5) was previously documented as a component of the Cullin3-RING ligase (CRL3). It has been reported that KCTD5 can induce enrichment of polyubiquitinated proteins, and KCTD5-based CRL3 destabilizes several proteins. In our present study, we report that KCTD5 may physically interact with ΔNp63α, which is a member of the p53 family. Our further investigation revealed that Cullin3/KCTD5 can induce monoubiquitination of ΔNp63α. Cullin3/KCTD5 downregulates the DNA-binding affinity of ΔNp63α, impairing either its transactivity or its transinhibitory activity. Functionally, Cullin3/KCTD5 abates the proproliferation activity of ΔNp63α. These findings suggest that KCTD5-based CRL3 may mediate monoubiquitination and is a novel regulator of ΔNp63α.

ΔNp63α down-regulates c-Myc modulator MM1 via E3 ligase HERC3 in the regulation of cell senescence.

p63 and c-Myc are key transcription factors controlling genes involved in the cell cycle and cellular senescence. We previously reported that p63α can destabilize MM1 protein to derepress c-Myc, resulting in cell cycle progress and tumorigenesis. However, how the proteasomal degradation of MM1 is facilitated remains unclear. In the present study, we identified a novel E3 ligase, HERC3, which can mediate ubiquitination of MM1 and promote its proteasome-dependent degradation. We found that ΔNp63α transcriptionally up-regulates HERC3 and knockdown of HERC3 abrogates ΔNp63α-induced down-regulation of MM1. Either overexpression of MM1 or ablation of HERC3 induces cell senescence, while knockdown of MM1 rescues cell senescence induced by deficiency of either ΔNp63α or HERC3, implicating the involvement of the ΔNp63α/HERC3/MM1/c-Myc axis in the modulation of cell senescence. Additionally, our Oncomine analysis indicates activation of the ΔNp63α/HERC3/MM1/c-Myc axis in invasive breast carcinoma. Together, our data illuminate a novel axis regulating cell senescence: ΔNp63α stimulates transcription of E3 ligase HERC3, which mediates ubiquitination of c-Myc modulator MM1 and targets it to proteasomal degradation; subsequently, c-Myc is derepressed by ΔNp63α, thereby cell senescence is modulated by this axis. Our work provides a new interpretation of crosstalk between p63 and c-Myc, and also sheds new light on ΔNp63α-controlled cell senescence and tumorigenesis.

[Cytogenetic analysis and phenotype location analysis on the karyotype of a ring chromosome 21 syndrome].

OBJECTIVE: To search the forming cause and the correlation between the clinical phenotype and chromosome band by the cytogenetic analysis on a case of ring chromosome 21 syndrome. METHODS: Identification and location of 21 ring chromosome were performed with the G-banding, C-banding, N-banding, high-resolution banding and fluorescence in situ hybridization (FISH) techniques. RESULTS: It was found that the karyotypes of the patient's parents are normal. The patient's karyotype is 46,XY, r(21)[91]/46,XY,r(21;21)(p11q22.3;p11q22.3) [5]/45,XY,-21[4]. CONCLUSION: The clinical phenotype of ring chromosome 21 syndrome is related to the deletion of distal segment of 21q, and the abnormal sexual development of male is related with the deletion of 21q22.3.