Circadian Rhythms and Sleep Are Dependent Upon Expression Levels of Key Ubiquitin Ligase Ube3a.

Normal neurodevelopment requires precise expression of the key ubiquitin ligase gene Ube3a. Comparing newly generated mouse models for Ube3a downregulation (models of Angelman syndrome) vs. Ube3a upregulation (models for autism), we find reciprocal effects of Ube3a gene dosage on phenotypes associated with circadian rhythmicity, including the amount of locomotor activity. Consistent with results from neurons in general, we find that Ube3a is imprinted in neurons of the suprachiasmatic nuclei (SCN), the pacemaking circadian brain locus, despite other claims that SCN neurons were somehow exceptional to these imprinting rules. In addition, Ube3a-deficient mice lack the typical drop in wake late in the dark period and have blunted responses to sleep deprivation. Suppression of physical activity by light in Ube3a-deficient mice is not due to anxiety as measured by behavioral tests and stress hormones; quantification of stress hormones may provide a mechanistic link to sleep alteration and memory deficits caused by Ube3a deficiency, and serve as an easily measurable biomarker for evaluating potential therapeutic treatments for Angelman syndrome. We conclude that reduced Ube3a gene dosage affects not only neurodevelopment but also sleep patterns and circadian rhythms.

Targeted modification of the Per2 clock gene alters circadian function in mPer2luciferase (mPer2Luc) mice.

Modification of the Per2 clock gene in mPer2Luc reporter mice significantly alters circadian function. Behavioral period in constant dark is lengthened, and dissociates into two distinct components in constant light. Rhythms exhibit increased bimodality, enhanced phase resetting to light pulses, and altered entrainment to scheduled feeding. Mechanistic mathematical modelling predicts that enhanced protein interactions with the modified mPER2 C-terminus, combined with differential clock regulation among SCN subregions, can account for effects on circadian behavior via increased Per2 transcript and protein stability. PER2::LUC produces greater suppression of CLOCK:BMAL1 E-box activity than PER2. mPer2Luc carries a 72 bp deletion in exon 23 of Per2, and retains a neomycin resistance cassette that affects rhythm amplitude but not period. The results show that mPer2Luc acts as a circadian clock mutation illustrating a need for detailed assessment of potential impacts of c-terminal tags in genetically modified animal models.

Circadian biology and sleep in monogenic neurological disorders and its potential application in drug discovery.

Sleep disturbances are common in people with monogenic neurological disorders and they dramatically affect the life of individuals with the disorders and their families. The associated sleep problems are probably caused by multiple factors that have not been elucidated. Study of the underlying molecular cause, behavioral phenotypes, and reciprocal interactions in several single-gene disorders (Angelman Syndrome, Fragile X Syndrome, Rett Syndrome, and Huntington's Disease) leads to the suggestion that sleep disruption and other symptoms may directly result from abnormal operation of circadian systems due to genetic alteration and/or conflicting environmental cues for clock entrainment. Therefore, because circadian patterns modify the symptoms of neurological disorders, treatments that modulate our daily rhythms may identify heretofore unappreciated therapies for the underlying disorders.

Coupling optogenetic stimulation with NanoLuc-based luminescence (BRET) Ca++ sensing.

Optogenetic techniques allow intracellular manipulation of Ca++ by illumination of light-absorbing probe molecules such as channelrhodopsins and melanopsins. The consequences of optogenetic stimulation would optimally be recorded by non-invasive optical methods. However, most current optical methods for monitoring Ca++ levels are based on fluorescence excitation that can cause unwanted stimulation of the optogenetic probe and other undesirable effects such as tissue autofluorescence. Luminescence is an alternate optical technology that avoids the problems associated with fluorescence. Using a new bright luciferase, we here develop a genetically encoded Ca++ sensor that is ratiometric by virtue of bioluminescence resonance energy transfer (BRET). This sensor has a large dynamic range and partners optimally with optogenetic probes. Ca++ fluxes that are elicited by brief pulses of light to cultured cells expressing melanopsin and to neurons-expressing channelrhodopsin are quantified and imaged with the BRET Ca++ sensor in darkness, thereby avoiding undesirable consequences of fluorescence irradiation.

Ube3a imprinting impairs circadian robustness in Angelman syndrome models.

BACKGROUND: The paternal allele of Ube3a is silenced by imprinting in neurons, and Angelman syndrome (AS) is a disorder arising from a deletion or mutation of the maternal Ube3a allele, which thereby eliminates Ube3a neuronal expression. Sleep disorders such as short sleep duration and increased sleep onset latency are very common in AS. RESULTS: We found a unique link between neuronal imprinting of Ube3a and circadian rhythms in two mouse models of AS, including enfeebled circadian activity behavior and slowed molecular rhythms in ex vivo brain tissues. As a consequence of compromised circadian behavior, metabolic homeostasis is also disrupted in AS mice. Unsilencing the paternal Ube3a allele restores functional circadian periodicity in neurons deficient in maternal Ube3a but does not affect periodicity in peripheral tissues that are not imprinted for uniparental Ube3a expression. The ubiquitin ligase encoded by Ube3a interacts with the central clock components BMAL1 and BMAL2. Moreover, inactivation of Ube3a expression elevates BMAL1 levels in brain regions that control circadian behavior of AS-model mice, indicating an important role for Ube3a in modulating BMAL1 turnover. CONCLUSIONS: Ube3a expression constitutes a direct mechanistic connection between symptoms of a human neurological disorder and the central circadian clock mechanism. The lengthened circadian period leads to delayed phase, which could explain the short sleep duration and increased sleep onset latency of AS subjects. Moreover, we report the pharmacological rescue of an AS phenotype, in this case, altered circadian period. These findings reveal potential treatments for sleep disorders in AS patients.

Circadian disruption leads to insulin resistance and obesity.

BACKGROUND: Disruption of circadian (daily) timekeeping enhances the risk of metabolic syndrome, obesity, and type 2 diabetes. While clinical observations have suggested that insulin action is not constant throughout the 24 hr cycle, its magnitude and periodicity have not been assessed. Moreover, when circadian rhythmicity is absent or severely disrupted, it is not known whether insulin action will lock to the peak, nadir, or mean of the normal periodicity of insulin action. RESULTS: We used hyperinsulinemic-euglycemic clamps to show a bona fide circadian rhythm of insulin action; mice are most resistant to insulin during their daily phase of relative inactivity. Moreover, clock-disrupted Bmal1-knockout mice are locked into the trough of insulin action and lack rhythmicity in insulin action and activity patterns. When rhythmicity is rescued in the Bmal1-knockout mice by expression of the paralogous gene Bmal2, insulin action and activity patterns are restored. When challenged with a high-fat diet, arhythmic mice (either Bmal1-knockout mice or wild-type mice made arhythmic by exposure to constant light) were obese prone. Adipose tissue explants obtained from high-fat-fed mice have their own periodicity that was longer than animals on a chow diet. CONCLUSIONS: This study provides rigorous documentation for a circadian rhythm of insulin action and demonstrates that disturbing the natural rhythmicity of insulin action will disrupt the rhythmic internal environment of insulin sensitive tissue, thereby predisposing the animals to insulin resistance and obesity.

Immunogenicity of four complementary deoxyribonucleic acid fragments from rabbit zona pellucida 3 and their effects on fertility.

OBJECTIVE: To evaluate the exact region in different exons of rabbit zona pellucida (ZP)3 involved in recognition and binding between sperm and the ZP. DESIGN: Prospective study of a female immunocontraceptive. SETTING: State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences. ANIMAL(S): BALB/C mice. INTERVENTION(S): Immunization recombinant vaccines. MAIN OUTCOME MEASURE(S): Oocyte immunofluorescence and immunohistochemistry. RESULT(S): The immunogenicity and effects on fertility of these four fragments we used were different. Except for the ZP domain, the other three fragments of rabbit ZP3 may be useful as antigen to elicit antibodies. Antiserum was specific and obvious. The fertility of mice after immunization decreased slightly compared with the control. CONCLUSION(S): The most effective fragment that is associated with the sperm binding was from sequences contained in exons 5-8 or oligosaccharide linked to this region. Exons 5-8 or oligosaccharide linked to this region may exist outside of the ZP matrix and be safe for use as the antigen. The ZP domain may be not related to the recognition and binding.

Apoptosis and tumor inhibition induced by human chorionic gonadotropin beta in mouse breast carcinoma.

For many breast cancer patients, human chorionic gonadotropin beta (hCGbeta), which is a subunit of a hormone produced by the trophoblast and is essential for maintaining pregnancy, is expressed in the breast cancer cells. However, the mechanism as to how the CGbeta in cell affects the cancer development is not very clear. Mouse breast carcinoma 4T1 with stably hCGbeta expression (4T1-hCGbeta) was established and transplanted into the Balb/c mouse abdominal mammary gland. hCGbeta suppressed breast cancer cell viability in vitro, and dramatically inhibited tumor growth and attenuated tumor vessel formation in vivo. An 86-88% reduction in tumor volume in animals injected with breast cancer expressing hCGbeta, as opposed to those injected with breast cancer without hCGbeta expression, was observed. The production of p21 was promoted by hCGbeta, whereas the Cdk2 was decreasing. These indicate that p21 signal pathway is involved in this process. Significant apoptosis was also detected in hCGbeta-expressing breast cancer cells as well as the enhancement of Bax protein expression. Moreover, hCGbeta blocked the blood vessels formation by inhibiting the expression of MMP9 and VEGF. Further hormone secretion analyses show that the anti-tumor activity induced by hCGbeta is not related to the endocrine function.

M and N proteins of SARS coronavirus induce apoptosis in HPF cells.

BACKGROUND: SARS-associated coronavirus (SARS-CoV) induced cell apoptosis and its structural proteins may play a role in this process. OBJECTIVES: To determine whether the structural proteins M and N of SARS-CoV induce apoptosis. STUDY DESIGN: We investigated human pulmonary fibroblast (HPF) cells, were transfected with plasmids containing the M or N gene, by TdT-mediated dUTP nick end labeling (TUNEL), Hoechst 33342 staining for nuclei, and observation of morphology. RESULTS: We found that in the absence of serum about 16.34% of cells transfected by pcDNA3.1-M and 21.72% of N-transfected cells showed typical apoptotic characteristics, significantly different from mock-transfected cells (only 6.23%, p<0.01). Furthermore, the cells that were co-transfected with M and N proteins showed more obvious phenomena of cell death (about 36.03%). There was a statistical significance between M-transfected cells and co-transfected cells (p<0.01), and a remarkable difference between N-transfected cells and co-transfected cells (p<0.01). CONCLUSIONS: The results show that M and N proteins of SARS-CoV can induce apoptosis of HPF cells. Co-transfection of M and N enhances the induction of apoptosis by M or N alone, which also suggests that the structural proteins of SARS-CoV may play an important role not only in the process of invasion but also in the pathogenetic process in cells.

Evaluation of the contraceptive potential of brZPCp vaccine in BALB/c mice: their safety and efficacy.

In this study we have examined the potential ability of Microtus branditi partial ZPC (brZPCp) cDNA sequence (436-1150 nt) as a target for immunocontraception. Immunogenicity studies and fertility trials were performed in BALB/c mice using recombinant construction pCR3.1-brZPC(p). ELISA outcome indicated that antibodies could be generated by immunized mice, and IgG titer was increased compared to the control. Immunohistochemistry outcome indicated that antibodies could recognize native ZP in vivo, which in turn, prevented the binding of sperm to ovulated eggs. Antibodies could also recognize recombinant protein expressed by BL21 in vitro, which was confirmed by SDS-PAGE and Western blot. Fertility rate was reduced by 45% compared to the control immunized with pCR3.1. Meanwhile, there was no incidence of significant ovarian pathology in treated mice. This experiment indicates that this vaccine can elicit the specific antibody which binds exactly to the corresponding ZPC. This construction is proved to be immunogenic, and can reduce fertility without obvious oophoritis. The result in this study suggests a potentially important method for controlling population for its safety and easy production.

The expression of membrane protein augments the specific responses induced by SARS-CoV nucleocapsid DNA immunization.

Nucleocapsid protein plays a critical role in SARS-CoV pathogenesis, and high-level anti-nucleocapsid antibodies are detected in the patients infected by severe acute respiratory syndrome-associated coronavirus (SARS-CoV). Several studies have shown that there exists an interaction between nucleocapsid (N) and membrane (M) protein. In this paper, we investigate whether the expression of membrane protein can affect the immune responses induced by nucleocapsid DNA immunization. Two recombinant plasmids containing M and N coding sequence were constructed. Moreover, in order to get the antigen for ELISA and in vitro stimulation assay, N protein were expressed and purified from E. coli bacteria. Injection of 20mug of the mixture of pVAX1-M and pVAX1-N into the Balb/c mice could elicit the humoral and cellular responses. The ELISA analysis using the N antigen or inactivated SARS-CoV particles as capture antigen showed that co-injection of SARS-M could enhance N-induced antibody production, especially IgG2a subclass. After lymphocytes were stimulated with 10mug/ml purified N antigen, The CD4+ and CD8+ T cells of N and M plus N group were increased compared with those of control groups, and the M protein could augment the activation of lymphocytes induced by N DNA vaccine. Cytokine ELISA analysis revealed that co-injection of M could enhance the levels of IFN-gamma, IL-2 release induced by N antigen. Further experiments in field mouse also support the claim that membrane protein can augment the N-specific immune responses. Virus challenge test was conducted in BSL3 bio safety laboratory with Brandt's vole SARS-CoV model, and the results indicated that co-immunization of M and N antigens could reduce the mortality and pathological changes in lung from the virus infection.

Oral feeding and nasal instillation immunization with Microtus brandti lactate dehydrogenase C epitope DNA vaccine reduces fertility in mice via specific antibody responses.

The immune responses induced by Microtus brandti lactate dehydrogenase C4 DNA vaccine via oral feeding and nasal instillation in mouse were investigated. The number of newborns of the vaccinated mice was statistically significantly reduced compared with the control mice, but the vaccine failed to affect the birthrate, as all vaccinated mice gave birth.

The mouse chorionic gonadotropin beta-subunit-like (muCG beta l) molecule produced by tumor cells elicits the switch of T-cell immunity response from TH2 to TH1 in mice immunized with DNA vaccine based on rhesus monkey homologous CG beta (rmCG beta).

BACKGROUND: CG beta is expressed not only in placenta, but also in a wide range of tumors. To study DNA vaccine based on xenogeneic CG beta for cancer immuno-therapy, we investigated whether rhesus monkey CG beta (rmCG beta) DNA vaccine could induce protective T-cell responses and humoral responses in mouse. METHODS: We constructed a plasmid containing the rmCG beta coding sequence. Two cloned syngeneic SP2/0 myeloma cell lines that stably express muCG beta l (SP2/0-muCG beta l) and HN (SP2/0-HN) protein were established. Inoculation of these cell lines was made into mice that had been immunized with DNA vaccine. Specific IgG and IgG type were measured by ELISA and the cytokine expression was detected with RT-PCR. To measure the lymphocyte metabolic activity, the MTS assay was used. RESULTS: After injection of SP2/0-muCG beta l into mice that had been immunized with DNA vaccine, a significant increase in the IgG2a specific to the antigen (p < 0.05) and a decrease in the specific IgG1 (p < 0.05) were measured. The expression of T(H)1 but not T(H)2 cytokines, including IFN-gamma and IL-2, were detected in the splenocytes. However, injection of tumor cells expressing irrelevant or mock molecules into immunized mice could not induce these changes. The survival rate of vaccine-immunized mice injected with SP2/0-muCG beta l was as high as 58.3% after 55 days. CONCLUSIONS: The rmCG beta DNA vaccine has proved to be a potential strategy for protection against tumors with homologous molecules. The muCG beta l produced by tumors is able to elicit an immunity switch from T(H)2 to T(H)1 in vaccinated mice.