Network analysis of microRNA and mRNA seasonal dynamics in a highly plastic sensorimotor neural circuit

Chronometric Administration of Cyclophosphamide and a Double-Stranded DNA-Mix at Interstrand Crosslinks Repair Timing, Called "Karanahan" Therapy, Is Highly Efficient in a Weakly Immunogenic Lewis Carcinoma Model

Background and Aims: A new technology based on the chronometric administration of cyclophosphamide and complex composite double-stranded DNA-based compound, which is scheduled in strict dependence on interstrand crosslinks repair timing, and named “Karanahan”, has been developed. Being applied, this technology results in the eradication of tumor-initiating stem cells and full-scale apoptosis of committed tumor cells. In the present study, the efficacy of this novel approach has been estimated in the model of Lewis carcinoma.

Methods: To determine the basic indicative parameters for the approach, the duration of DNA repair in tumor cells, as well as their distribution along the cell cycle, have been assessed. Injections were done into one or both tumors in femoral region of the engrafted mice in accordance with the developed regimen. Four series of experiments were carried out at different periods of time. The content of poorly differentiated CD34⁺/TAMRA+ cells in the bone marrow and peripheral blood has been determined. Immunostaining followed by the flow cytometry was used to analyze the subpopulations of immune cells.

Results: The high antitumor efficacy of the new technology against the developed experimental Lewis carcinoma was shown. It was found that the therapy efficacy depended on the number of tumor growth sites, seasonal and annual peculiarities. In some experiments, a long-term remission has been reached in 70% of animals with a single tumor and in 60% with two tumors. In mice with two developed grafts, mobilization capabilities of both poorly differentiated hematopoietic cells of the host and tumor stem-like cells decrease significantly. Being applied, this new technology was shown to activate a specific immune response. There is an increase in the number of NK cell populations in the blood, tumor, and spleen, killer T cells and T helper cells in the tumor and spleen, CD11b+Ly-6C+ and CD11b+Ly-6G+ cells in the tumor. A population of mature dendritic cells is found in the tumor.

Conclusion: The performed experiments indicate the efficacy of the Karanahan approach against incurable Lewis carcinoma. Thus, the discussed therapy is a new approach for treating experimental neoplasms, which has a potential as a personalized anti-tumor therapeutic approach in humans.

Inhibition of miR-128 Enhances Vocal Sequence Organization in Juvenile Songbirds

The molecular mechanisms underlying learned vocal communication are not well characterized. This is a major barrier for developing treatments for conditions affecting social communication, such as autism spectrum disorder (ASD). Our group previously generated an activity-dependent gene expression network in the striatopallidal song control nucleus, Area X, in adult zebra finches to identify master regulators of learned vocal behavior. This dataset revealed that the two host genes for microRNA-128, ARPP21 and R3HDM1, are among the top genes whose expression correlates to how much birds sing. Here we examined whether miR-128 itself is behaviorally regulated in Area X and found that its levels decline with singing. We hypothesized that reducing miR-128 during the critical period for vocal plasticity would enhance vocal learning. To test this, we bilaterally injected an antisense miR-128 construct (AS miR-128) or a control scrambled sequence into Area X at post-hatch day 30 (30 d) using sibling-matched experimental and control pupils. The juveniles were then returned to their home cage and raised with their tutors. Strikingly, inhibition of miR-128 in young birds enhanced the organization of learned vocal sequences. Tutor and pupil stereotypy scores were positively correlated, though the correlation was stronger between tutors and control pupils compared to tutors and AS miR-128 pupils. This difference was driven by AS miR-128 pupils achieving higher stereotypy scores despite their tutors’ lower syntax scores. AS miR-128 birds with tutors on the higher end of the stereotypy spectrum were more likely to produce songs with faster tempos relative to sibling controls. Our results suggest that low levels of miR-128 facilitate vocal sequence stereotypy. By analogy, reducing miR-128 could enhance the capacity to learn to speak in patients with non-verbal ASD. To our knowledge, this study is the first to directly link miR-128 to learned vocal communication and provides support for miR-128 as a potential therapeutic target for ASD.

Music-listening regulates human microRNA expression

Music-listening and performance have been shown to affect human gene expression. In order to further elucidate the biological basis of the effects of music on the human body, we studied the effects of music-listening on gene regulation by sequencing microRNAs of the listeners (Music Group) and their controls (Control Group) without music exposure. We identified upregulation of six microRNAs (hsa-miR-132-3p, hsa-miR-361-5p, hsa-miR-421, hsa-miR-23a-3p, hsa-miR-23b-3p, hsa-miR-25-3p) and downregulation of two microRNAs (hsa-miR-378a-3p, hsa-miR-16-2-3p) in Music Group with high musical aptitude. Some upregulated microRNAs were reported to be responsive to neuronal activity (miR-132, miR-23a, miR-23b) and modulators of neuronal plasticity, CNS myelination, and cognitive functions like long-term potentiation and memory. miR-132 plays a critical role in regulating TAU protein levels and is important for preventing tau protein aggregation that causes Alzheimer's disease. miR-132 and DICER, upregulated after music-listening, protect dopaminergic neurons and are important for retaining striatal dopamine levels. Some of the transcriptional regulators (FOS, CREB1, JUN, EGR1, and BDNF) of the upregulated microRNAs were immediate early genes and top candidates associated with musical traits. BDNF and SNCA, co-expressed and upregulated in music-listening and music-performance, are both are activated by GATA2, which is associated with musical aptitude. Several miRNAs were associated with song-learning, singing, and seasonal plasticity networks in songbirds. We did not detect any significant changes in microRNA expressions associated with music education or low musical aptitude. Our data thereby show the importance of inherent musical aptitude for music appreciation and for eliciting the human microRNA response to music-listening.

Rapamycin blocks the neuroprotective effects of sex steroids in the adult birdsong system

In adult songbirds, the telencephalic song nucleus HVC and its efferent target RA undergo pronounced seasonal changes in morphology. In breeding birds, there are increases in HVC volume and total neuron number, and RA neuronal soma area compared to nonbreeding birds. At the end of breeding, HVC neurons die through caspase-dependent apoptosis and thus, RA neuron size decreases. Changes in HVC and RA are driven by seasonal changes in circulating testosterone (T) levels. Infusing T, or its metabolites 5α-dihydrotestosterone (DHT) and 17 β-estradiol (E2), intracerebrally into HVC (but not RA) protects HVC neurons from death, and RA neuron size, in nonbreeding birds. The phosphoinositide 3-kinase (PI3K)-Akt (a serine/threonine kinase)-mechanistic target of rapamycin (mTOR) signaling pathway is a point of convergence for neuroprotective effects of sex steroids and other trophic factors. We asked if mTOR activation is necessary for the protective effect of hormones in HVC and RA of adult male Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii). We transferred sparrows from breeding to nonbreeding hormonal and photoperiod conditions to induce regression of HVC neurons by cell death and decrease of RA neuron size. We infused either DHT + E2, DHT + E2 plus the mTOR inhibitor rapamycin, or vehicle alone in HVC. Infusion of DHT + E2 protected both HVC and RA neurons. Coinfusion of rapamycin with DHT + E2, however, blocked the protective effect of hormones on HVC volume and neuron number, and RA neuron size. These results suggest that activation of mTOR is an essential downstream step in the neuroprotective cascade initiated by sex steroid hormones in the forebrain.

Spring is in the air: seasonal profiles indicate vernal change of miRNA activity

The envisioned application of miRNAs as diagnostic or prognostic biomarkers calls for an in-depth understanding of their distribution and variability in different physiological states. While effects with respect to ethnic origin, age, or gender are known, the inter-individual variability of miRNAs across the four seasons remained largely hidden. We sequentially profiled the complete repertoire of blood-borne miRNAs for 25 physiologically normal individuals in spring, summer, fall, and winter (altogether 95 samples) and validated the results on 292 individuals (919 samples collected with the Mitra home sampling device) by RT-qPCR. Principal variance component analysis suggests that the largest variability observed in miRNA expression is due to individual variability and the individuals' gender. But the results also highlight a deviation of miRNA activity in samples collected during spring time. Following adjustment for multiple testing, remarkable differences are observed between spring and fall (77 miRNAs). The two most dys-regulated miRNAs were miR-181c-5p and miR-106b-5p (adjusted p-value of 0.007). Other significant miRNAs include miR-140-3p, miR-21-3p, and let-7c-5p. The dys-regulation was validated by RT-qPCR. Systems biology analysis further provides strong evidence for the immunological origin of the signals: dys-regulated miRNAs are enriched in CD56 cells and belong to various signalling and immune-system-related pathways. Our data suggest that besides known confounding factors such as age and sex, also the season in which a test is conducted might have a considerable influence on the expression of blood-borne miRNAs and subsequently might interfere with diagnosis based on such signatures.

Single neuron serotonin receptor subtype gene expression correlates with behaviour within and across three molluscan species

The marine mollusc, Pleurobranchaea californica varies daily in whether it swims and this correlates with whether serotonin (5-HT) enhances the strength of synapses made by the swim central pattern generator neuron, A1/C2. Another species, Tritonia diomedea, reliably swims and does not vary in serotonergic neuromodulation. A third species, Hermissenda crassicornis, never produces this behaviour and lacks the neuromodulation. We found that expression of particular 5-HT receptor subtype (5-HTR) genes in single neurons correlates with swimming. Orthologues to seven 5-HTR genes were identified from whole-brain transcriptomes. We isolated individual A1/C2 neurons and sequenced their RNA or measured 5-HTR gene expression using absolute quantitative PCR. A1/C2 neurons isolated from Pleurobranchaea that produced a swim motor pattern just prior to isolation expressed 5-HT2a and 5-HT7 receptor genes, as did all Tritonia samples. These subtypes were absent from A1/C2 isolated from Pleurobranchaea that did not swim on that day and from Hermissenda A1/C2 neurons. Expression of other receptors was not correlated with swimming. This suggests that these 5-HTRs may mediate the modulation of A1/C2 synaptic strength and play an important role in swimming. Furthermore, it suggests that regulation of receptor expression could underlie daily changes in behaviour as well as evolution of behaviour.

Efficacy of a new cancer treatment strategy based on eradication of tumor-initiating stem cells in a mouse model of Krebs-2 solid adenocarcinoma

Krebs-2 solid carcinoma was cured using a new “3+1” strategy for eradication of Krebs-2 tumor-initiating stem cells. This strategy was based on synchronization of these cells in a treatment-sensitive phase of the cell cycle. The synchronization mechanism, subsequent destruction of Krebs-2 tumor-initiating stem cells, and cure of mice from a solid graft were found to depend on the temporal profile of the interstrand cross-link repair cycle. Also, the temporal profile of the Krebs-2 interstrand repair cycle was found to have a pronounced seasonal cyclicity at the place of experiments (Novosibirsk, Russia). As a result, the therapeutic effect that is based on application of the described strategy, originally developed for the “winter repair cycle” (November−April), is completely eliminated in the summer period (June−September). We conclude that оne of the possible and the likeliest reasons for our failure to observe the therapeutic effects was the seasonal cyclicity in the duration of the interstrand repair cycle, the parameter that is central to our strategy.

Commentary: miR-132/212 Modulates Seasonal Adaptation and Dendritic Morphology of the Central Circadian Clock

Daily rhythms in behavior and physiology are coordinated by an endogenous clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus. This central pacemaker also relays day length information to allow for seasonal adaptation, a process for which melatonin signaling is essential. How the SCN encodes day length is not fully understood. MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression by directing target mRNAs for degradation or translational repression. The miR-132/212 cluster plays a key role in facilitating neuronal plasticity, and miR-132 has been shown previously to modulate resetting of the central clock. A recent study from our group showed that miR-132/212 in mice is required for optimal adaptation to seasons and non-24-hour light/dark cycles through regulation of its target gene, methyl CpG-binding protein (MeCP2), in the SCN and dendritic spine density of SCN neurons. Furthermore, in the seasonal rodent Mesocricetus auratus (Syrian hamster), adaptation to short photoperiods is accompanied by structural plasticity in the SCN independently of melatonin signaling, thus further supporting a key role for SCN structural and, in turn, functional plasticity in the coding of day length. In this commentary, we discuss our recent findings in context of what is known about day length encoding by the SCN, and propose future directions.

miR-132/212 Modulates Seasonal Adaptation and Dendritic Morphology of the Central Circadian Clock

The central circadian pacemaker, the suprachiasmatic nucleus (SCN), encodes day length information by mechanisms that are not well understood. Here, we report that genetic ablation of miR-132/212 alters entrainment to different day lengths and non-24 hr day-night cycles, as well as photoperiodic regulation of Period2 expression in the SCN. SCN neurons from miR-132/212-deficient mice have significantly reduced dendritic spine density, along with altered methyl CpG-binding protein (MeCP2) rhythms. In Syrian hamsters, a model seasonal rodent, day length regulates spine density on SCN neurons in a melatonin-independent manner, as well as expression of miR-132, miR-212, and their direct target, MeCP2. Genetic disruption of Mecp2 fully restores the level of dendritic spines of miR-132/212-deficient SCN neurons. Our results reveal that, by regulating the dendritic structure of SCN neurons through a MeCP2-dependent mechanism, miR-132/212 affects the capacity of the SCN to encode seasonal time.