Analyzing the photoassociation spectrum of ultracold 85Rb 133Cs molecule in (3)3Σ+ state.

We establish a theoretical model to analyze the photoassociative spectroscopy of 85Rb 133Cs molecules in the (3)3Σ+ state. The vibrational energy, spin-spin coupling constant, and hyperfine interaction constant of the (3)3Σ+ state are determined based on nine observed vibrational levels. Consequently, the Rydberg-Klein-Rees potential energy curve of the (3)3Σ+ state is obtained and compared with the ab initial potential energy curve. Our model can be adopted to analyze the photoassociative spectroscopy of other heteronuclear alkali-metal diatomic molecules in the (3)3Σ+ state.

Research on the improvement effect of Saposhnikovia divaricata (Trucz.) Schischk on rheumatoid arthritis based on the "component-target-pathway" association.

OBJECTIVE: To investigate the therapeutic effect and mechanism of the traditional Chinese medicine Saposhnikovia divaricata (Trucz.) Schischk in rats with complete Freund's adjuvant-induced rheumatoid arthritis (RA). METHODS: The chemical targets and RA targets of Saposhnikovia divaricata (Trucz.) Schischk were acquired by the network pharmacological method. The complete Freund's adjuvant-induced rat RA model was used to further explore the mechanism of Saposhnikovia divaricata (Trucz.) Schischk in improving RA. Pathological changes in the volume of toes, body weight and synovial tissues of joints as well as serum inflammatory factor levels before and after the intervention of Saposhnikovia divaricata (Trucz.) Schischk were investigated. The key metabolic pathways were screened by correlations between metabolites and key targets. Finally, a quantitative analysis of key targets and metabolites was experimentally validated. RESULTS: Saposhnikovia divaricata (Trucz.) Schischk administration increased body weight, mitigated foot swelling and downregulated inflammatory cytokine levels in model rats. The histopathology showed that treatment with Saposhnikovia divaricata (Trucz.) Schischk can induce inflammatory cell infiltration and synovial hyperplasia and obviously reduce cartilage injuries, thus improving arthritis symptoms in rats. According to the network pharmacology-metabonomics association analysis results, the purine metabolic signaling pathway might be the key pathway for RA intervention with Saposhnikovia divaricata (Trucz.) Schischk. Targeted metabonomics, Western blotting (WB) and reverse transcription-polymerase chain reaction (RT‒PCR) assays showed that the recombinant adenosine deaminase (ADA) mRNA expression level and metabolic level of inosine in Saposhnikovia divaricata (Trucz.) Schischk administration group were lower than those of the model group. This reflected that Saposhnikovia divaricata (Trucz.) Schischk could improve RA by downregulating ADA mRNA expression levels and the metabolic level of inosine in the purine signaling pathway. CONCLUSION: Based on the "component-disease-target" association analysis, this study concludes that Saposhnikovia divaricata (Trucz.) Schischk improves complete Freund's adjuvant-induced RA symptoms in rats mainly by downregulating ADA mRNA expression levels in the purine metabolic signaling pathway, mitigating foot swelling, improving the levels of serum inflammatory factors (IL-1ß, IL-6 and TNF-α), and decreasing the ADA protein expression level to intervene in purine metabolism.

F-domain valency determines outcome of signaling through the angiopoietin pathway.

Angiopoietins 1 and 2 (Ang1 and Ang2) regulate angiogenesis through their similar F-domains by activating Tie2 receptors on endothelial cells. Despite the similarity in the underlying receptor-binding interaction, the two angiopoietins have opposite effects: Ang1 induces phosphorylation of AKT, strengthens cell-cell junctions, and enhances endothelial cell survival while Ang2 can antagonize these effects, depending on cellular context. To investigate the molecular basis for the opposing effects, we examined the phenotypes of a series of computationally designed protein scaffolds presenting the Ang1 F-domain in a wide range of valencies and geometries. We find two broad phenotypic classes distinguished by the number of presented F-domains: Scaffolds presenting 3 or 4 F-domains have Ang2-like activity, upregulating pFAK and pERK but not pAKT, while scaffolds presenting 6, 8, 12, 30, or 60 F-domains have Ang1-like activity, upregulating pAKT and inducing migration and vascular stability. The scaffolds with 6 or more F-domains display super-agonist activity, producing stronger phenotypes at lower concentrations than Ang1. Tie2 super-agonist nanoparticles reduced blood extravasation and improved blood-brain barrier integrity four days after a controlled cortical impact injury.

Identification of DELLA gene family in head cabbage and analysis of mRNA transport in the heterograft.

DELLA gene family is involved in the regulation of signal transduction of plant hormones. mRNAs of GA insensitive (GAI), the member of DELLA gene family, are also signaling molecules of long-distance transport in plants. Genome-wide identification and mRNA transport analysis of the members of DELLA gene family in head cabbage (Brassica oleracea var. capitata) can provide basic data for their application in head cabbage. In this study, five members of DELLA gene family (BoRGA1, BoRGA2, BoRGL1, BoRGL2, and BoRGL3) were identified in head cabbage using genome and transcriptome data. However, head cabbage lacked a GAI gene in its genome. The scion (head cabbage, inbred line G27) and the rootstock Chinese flowering cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee) (sijiucaixin) were cleft-grafted together to produce the heterograft. Inflorescence stem of the rootstock and the corresponding inflorescence stem in Chinese flowering cabbage seedlings (as controls) were purified and analyzed with transcriptome sequencing. The total of 8, 9, 3, 5, and 1 exogenous read(s), derived respectively from BoRGA1, BoRGA2, BoRGL1, BoRGL2, and BoRGL3, were identified in the transcriptomes of the rootstocks. Nevertheless, mRNA transport of DELLA family genes from scion to rootstock did not increase the transcriptional level of the members of DELLA gene family in the rootstocks. Correlation analysis suggested that mRNA transport efficiency of the DELLA family genes was correlated with the sequence and the transcriptional level of the respective DELLA gene in the scion (head cabbage). This study lays the foundation for further investigation on the molecular mechanism of mRNA transport of the members of DELLA gene family in head cabbage.

[Determination of 10 mycotoxins in Hippophae Fructus medicinal and edible products by ultra-performance liquid chromatography- tandem mass spectrometry].

An analytical method for 10 mycotoxins in Hippophae Fructus medicinal and edible products was established in this study, and the contamination of their mycotoxins was analyzed. First of all, the mixed reference solution of ten mycotoxins such as aflatoxin, ochratoxin, zearalenone, and dexoynivalenol was selected as the control, and the Hippophae Fructus medicinal and edible products were prepared. Secondly, based on the ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) technology, 10 mycotoxins in Hippophae Fructus medicinal and edible products were quantitatively investigated and their content was determined. Finally, the contamination of mycotoxins was analyzed and evaluated. The optimal analysis conditions were determined, and the methodological inspection results showed that the 10 mycotoxins established a good linear relationship(r>0.99). The method had good repeatability, test sample specificity, stability, and instrument precision. The average recovery rates of 10 mycotoxins in Hippophae Fructus medicinal products, edible solids, and edible liquids were 90.31%-109.4%, 87.86%-107.8%, and 85.61%-109.1%, respectively. Relative standard deviation(RSD) values were 0.22%-10%, 0.75%-13%, and 0.84%-8.5%, repsectively. Based on UPLC-MS/MS technology, the simultaneous determination method for the limits of 10 mycotoxins established in this study has fast detection speed, less matrix interference, high sensitivity, and accurate results, which is suitable for the limit examination of 10 mycoto-xins in Hippophae Fructus medicinal and edible products.

Preserved cardiac performance and adrenergic response in a rabbit model with decreased ryanodine receptor 2 expression.

Ryanodine receptor 2 (RyR2) is an ion channel in the heart responsible for releasing into the cytosol most of the Ca2+ required for contraction. Proper regulation of RyR2 is critical, as highlighted by the association between channel dysfunction and cardiac arrhythmia. Lower RyR2 expression is also observed in some forms of heart disease; however, there is limited information on the impact of this change on excitation-contraction (e-c) coupling, Ca2+-dependent arrhythmias, and cardiac performance. We used a constitutive knock-out of RyR2 in rabbits (RyR2-KO) to assess the extent to which a stable decrease in RyR2 expression modulates Ca2+ handling in the heart. We found that homozygous knock-out of RyR2 in rabbits is embryonic lethal. Remarkably, heterozygotes (KO+/-) show ~50% loss of RyR2 protein without developing an overt phenotype at the intact animal and whole heart levels. Instead, we found that KO+/- myocytes show (1) remodeling of RyR2 clusters, favoring smaller groups in which channels are more densely arranged; (2) lower Ca2+ spark frequency and amplitude; (3) slower rate of Ca2+ release and mild but significant desynchronization of the Ca2+ transient; and (4) a significant decrease in the basal phosphorylation of S2031, likely due to increased association between RyR2 and PP2A. Our data show that RyR2 deficiency, although remarkable at the molecular and subcellular level, has only a modest impact on global Ca2+ release and is fully compensated at the whole-heart level. This highlights the redundancy of RyR2 protein expression and the plasticity of the e-c coupling apparatus.

Increased mitochondrial nanotunneling activity, induced by calcium imbalance, affects intermitochondrial matrix exchanges.

Exchanges of matrix contents are essential to the maintenance of mitochondria. Cardiac mitochondrial exchange matrix content in two ways: by direct contact with neighboring mitochondria and over longer distances. The latter mode is supported by thin tubular protrusions, called nanotunnels, that contact other mitochondria at relatively long distances. Here, we report that cardiac myocytes of heterozygous mice carrying a catecholaminergic polymorphic ventricular tachycardia-linked RyR2 mutation (A4860G) show a unique and unusual mitochondrial response: a significantly increased frequency of nanotunnel extensions. The mutation induces Ca2+ imbalance by depressing RyR2 channel activity during excitation-contraction coupling, resulting in random bursts of Ca2+ release probably due to Ca2+ overload in the sarcoplasmic reticulum. We took advantage of the increased nanotunnel frequency in RyR2A4860G+/- cardiomyocytes to investigate and accurately define the ultrastructure of these mitochondrial extensions and to reconstruct the overall 3D distribution of nanotunnels using electron tomography. Additionally, to define the effects of communication via nanotunnels, we evaluated the intermitochondrial exchanges of matrix-targeted soluble fluorescent proteins, mtDsRed and photoactivable mtPA-GFP, in isolated cardiomyocytes by confocal microscopy. A direct comparison between exchanges occurring at short and long distances directly demonstrates that communication via nanotunnels is slower.

Sorcin ablation plus ß-adrenergic stimulation generate an arrhythmogenic substrate in mouse ventricular myocytes.

Sorcin, a penta-EF hand Ca2+-binding protein expressed in cardiomyocytes, is known to interact with ryanodine receptors and other Ca2+ regulatory proteins. To investigate sorcin's influence on cardiac excitation-contraction coupling and its role in the development of cardiac malfunctions, we generated a sorcin knockout (KO) mouse model. Sorcin KO mice presented ventricular arrhythmia and sudden death when challenged by acute stress induced by isoproterenol plus caffeine. Chronic stress, which was induced by transverse aortic constriction, significantly decreased the survival rate of sorcin KO mice. Under isoproterenol stimulation, spontaneous Ca2+ release events were frequently observed in sorcin KO cardiomyocytes. Sorcin KO hearts of adult, but not young mice developed overexpression of L-type Ca2+ channel and Na+-Ca2+ exchanger, which enhanced ICa and INCX. Consequently, spontaneous Ca2+ release events in sorcin KO cardiomyocytes were more likely to induce arrhythmogenic delayed afterdepolarizations. Our study demonstrates sorcin deficiency may trigger cardiac ventricular arrhythmias due to Ca2+ disturbances, and evidences the critical role of sorcin in maintaining Ca2+ homeostasis, especially during the adrenergic response of the heart.

Arrhythmogenesis in a catecholaminergic polymorphic ventricular tachycardia mutation that depresses ryanodine receptor function.

Current mechanisms of arrhythmogenesis in catecholaminergic polymorphic ventricular tachycardia (CPVT) require spontaneous Ca(2+) release via cardiac ryanodine receptor (RyR2) channels affected by gain-of-function mutations. Hence, hyperactive RyR2 channels eager to release Ca(2+) on their own appear as essential components of this arrhythmogenic scheme. This mechanism, therefore, appears inadequate to explain lethal arrhythmias in patients harboring RyR2 channels destabilized by loss-of-function mutations. We aimed to elucidate arrhythmia mechanisms in a RyR2-linked CPVT mutation (RyR2-A4860G) that depresses channel activity. Recombinant RyR2-A4860G protein was expressed equally as wild type (WT) RyR2, but channel activity was dramatically inhibited, as inferred by [(3)H]ryanodine binding and single channel recordings. Mice heterozygous for the RyR2-A4860G mutation (RyR2-A4860G(+/-)) exhibited basal bradycardia but no cardiac structural alterations; in contrast, no homozygotes were detected at birth, suggesting a lethal phenotype. Sympathetic stimulation elicited malignant arrhythmias in RyR2-A4860G(+/-) hearts, recapitulating the phenotype originally described in a human patient with the same mutation. In isoproterenol-stimulated ventricular myocytes, the RyR2-A4860G mutation decreased the peak of Ca(2+) release during systole, gradually overloading the sarcoplasmic reticulum with Ca(2+). The resultant Ca(2+) overload then randomly caused bursts of prolonged Ca(2+) release, activating electrogenic Na(+)-Ca(2+) exchanger activity and triggering early afterdepolarizations. The RyR2-A4860G mutation reveals novel pathways by which RyR2 channels engage sarcolemmal currents to produce life-threatening arrhythmias.

Comparison of the effectiveness and safety of one-stage versus two-stage bilateral total knee arthroplasty.

This study aims to evaluate the effectiveness and safety of the patients receiving simultaneous bilateral TKA (BTKA). A total of 93 consecutive patients with bilateral knee degenerative osteoarthritis from January 2008 to November 2013 were divided into two groups--one-stage group (bilateral TKA under a single anesthetic, n = 54) and two-stage group (bilateral TKA performed during two separate admissions, n = 39). The patients in the both group have a similar incidence of postoperative complications (p = 0.544). The one-stage BTKA can significantly (p < 0.05) decrease the operative time, length of stay, and hospital charges, when compared to two-stage BTKA. The patients in one-stage group have a significantly (p < 0.05) higher postoperative drainage, amount of hidden blood loss, amount of blood loss, allogeneic transfusion and rate of blood transfusion, compared with those in two-stage group. Patients in both groups had a similar KSS (p = 0.839) and ROM (p = 0.383). The findings suggests that one-stage BTKA may be safely performed with similar knee function to those of two-stage procedure, and has the added benefit of single anaesthetic, reduced costs and decreased hospital stay when compared to two-stage BTKA.

Application of sub-Doppler DAVLL to laser frequency stabilization in atomic cesium.

We achieve laser frequency stabilization by a simple technique based on sub-Doppler dichroic atomic vapor laser lock (DAVLL) in atomic cesium. The technique that combines saturated-absorption spectroscopy and Zeeman splitting of hyperfine structures allows us to obtain a modulation-free dispersion-like error signal for frequency stabilization. For the error signal, the dependence of peak-to-peak amplitude and the slope at the zero-crossing point on the magnetic field is studied by simulation and experiment. Based on the result, we obtain an available sub-Doppler DAVLL error signal with high sensitivity to the frequency drift by selecting an appropriate strength of the magnetic field. Ultimately, the fluctuation of the locked laser frequency is confined to below 0.5 MHz in a long term, exhibiting efficient suppression of frequency noise.

[Experimental study of ultralow frequency modulation photoassociation spectrum].

In the present paper, ultracold cesium atoms were obtained in magnetic optical trap using the laser cooling technology. The number of ultracold atoms is 10(7). The temperature of ultracold atoms is about 200 µK and the diameter of the ultracold atoms cloud is about 400 µm. The ultracold cesium molecules of excited states were formed using the photoassociation of ultracold atoms. The resolution of vib-rotational spectrum was studied under different scan rates of photossociation laser in the experiment. The resolution of vib-rotational spectrum becomes high when the scan rate of photossociation laser becomes slow. The cold atoms fluorescence was obtained using the high sensitive avalanche photo detector and the high resolution vib-rotational spectrum of ultracold cesium molecule in its first excited state of with dissociation limit long range state was obtained. The ultracold ground molecule was formed by controlled Raman photoassociation and the photoassociation laser must be locked to atom-molecular hyperfine transitions. The ultracold atoms photoassociation spectrum was modulated using ultra-low frequency. The first-order differential signal was optimized by changing modulation amplitude and modulation frequency. It provides a feedback signal to correct error of the laser. The laser frequency satisfies experimental requirement to form ultracold ground molecules using the controlled Raman photoassociation. This work is important for studies of ultracold atoms and molecules in confined space.

Hypericum perforatum L. protects against renal function decline in ovariectomy rat model by regulating expressions of NOS3 and AKT1 in AGE-RAGE pathway.

BACKGROUND: Hypericum perforatum L. (HPL) is a potential traditional Chinese medicine. It could promotes menopausal 'kidney-yin deficiency syndrome' that characterized by renal function decline. However, its potential pharmacological effect and mechanism remains unknown. OBJECTIVE: The aim of this study was to investigate whether HPL can improve menopausal renal function decline and to explore its mechanism of action. METHODS: The mainly ingredients of HPL were identified using UPLC-Q-TOF-MS/MS approach, and the potential therapeutic targets of HPL for renal function decline were chose via network pharmacology technique. The key therapeutic metabolites were selected through non-targeted metabolomic and chemometric methods. Then, the network were constructed and the key targets and metabolites were screened. At last, the validation experiments and mechanism exploring were adopted by using Immunofluorescence, enzyme-linked immunosorbent assay (ELISA), real-time PCR (RT-PCR), and western blotting assays. RESULTS: mainly ingredients of HPL were identified and determined 17 compounds and 29 targets were chose as mainly active compounds and potential therapeutic targets. Based on OVX induced renal decline rat model, after chemometric analysis, 59 endo-metabolites were selected as key therapeutic metabolites, and AGE-RAGE signal pathway in diabetes complications was enriched as the key pathway. By constructing a "disease-component-target" network, Hyperoside, Quercetrin, and quinic were selected as the key therapeutic compounds, and the AKT1 and NOS3 were selected as the key therapeutic targets. The results of ELISA, RT-PCR and western blot experiments indicated that HPL could rescue the abnormal expressions both of AKT1 and NOS3, as well as their related metabolites distortion. CONCLUSION: Our findings indicated that HPL regulated expression of AKT1 and NOS3 through modulating AGE-RAGE signaling pathway in OVX stimulated rats` renal dysfunction, implicating the potential values of HPL in menopause syndromes therapy.

De Novo Design of Integrin α5ß1 Modulating Proteins for Regenerative Medicine.

Integrin α5ß1 is crucial for cell attachment and migration in development and tissue regeneration, and α5ß1 binding proteins could have considerable utility in regenerative medicine and next-generation therapeutics. We use computational protein design to create de novo α5ß1-specific modulating miniprotein binders, called NeoNectins, that bind to and stabilize the open state of α5ß1. When immobilized onto titanium surfaces and throughout 3D hydrogels, the NeoNectins outperform native fibronectin and RGD peptide in enhancing cell attachment and spreading, and NeoNectin-grafted titanium implants outperformed fibronectin and RGD-grafted implants in animal models in promoting tissue integration and bone growth. NeoNectins should be broadly applicable for tissue engineering and biomedicine.

Simple, reliable, and nondestructive method for the measurement of vacuum pressure without specialized equipment.

We present a simple, reliable, and nondestructive method for the measurement of vacuum pressure in a magneto-optical trap. The vacuum pressure is verified to be proportional to the collision rate constant between cold atoms and the background gas with a coefficient k, which can be calculated by means of the simple ideal gas law. The rate constant for loss due to collisions with all background gases can be derived from the total collision loss rate by a series of loading curves of cold atoms under different trapping laser intensities. The presented method is also applicable for other cold atomic systems and meets the miniaturization requirement of commercial applications.

Fushenmu treatment ameliorates RyR2 with related metabolites in a zebrafish model of barium chloride induced arrhythmia.

BACKGROUND: Fushenmu (Pini Radix in Poria, FSM) is a folk parasitic herb that has been mainly used for palpitation and amnesiain in traditional Chinese medicine (TCM). Recently, as an individual herb or a component of formulations, Fushenmu exhibits therapeutic potential for the treatment of cardiac arrhythmias. Yet, how specific targets or pathways of Fushenmu inhibit arrhythmia has not yet been reported. METHODS: Here, based on clinical functional genomics, metabolomics and molecular biologic technologies, a network construction strategy was adopted to identify FSM therapeutic targets and biomarkers that might explore its functions. RESULTS: In this study, it was found that FSM recovered arrhythmia-associated heart failure in barium chloride (BaCl2) induced arrhythmic zebrafish embryos, as was evidenced by the shortened cardiac sinus venosus-bulbus arteriosus (SV-BA) distance, smaller cardiovascular bleeding areas, and reduced cardiomyocyte apoptosis. Moreover, analysis via ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-QTOF-ESI-MS/MS) components identification and network pharmacology prediction showed that 11 main active components of FSM acted on 33 candidate therapeutic targets. Metabolomic analysis also suggested that FSM could rescue 242 abnormal metabolites from arrhythmic zebrafish embryos. Further analysis based on the combination of target prediction and metabolomic results illustrated that FSM down-regulated Ryanodine Receptor 2 (RyR2) expressions, inhibited adrenaline and 3',5'-Cyclic AMP (cAMP) levels in a dose-dependent manner, which was confirmed by metabolites quantification and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) assay. CONCLUSION: In summary, this study revealed that FSM mitigated BaCl2 induced cardiac damage caused by arrhythmia by suppressing RyR2 expressions, decreasing adrenaline and cAMP through the adrenergic signalling pathway.

Top-down design of protein architectures with reinforcement learning.

As a result of evolutionary selection, the subunits of naturally occurring protein assemblies often fit together with substantial shape complementarity to generate architectures optimal for function in a manner not achievable by current design approaches. We describe a "top-down" reinforcement learning-based design approach that solves this problem using Monte Carlo tree search to sample protein conformers in the context of an overall architecture and specified functional constraints. Cryo-electron microscopy structures of the designed disk-shaped nanopores and ultracompact icosahedra are very close to the computational models. The icosohedra enable very-high-density display of immunogens and signaling molecules, which potentiates vaccine response and angiogenesis induction. Our approach enables the top-down design of complex protein nanomaterials with desired system properties and demonstrates the power of reinforcement learning in protein design.

Single Cell RNA Sequencing Reveals Human Tooth Type Identity and Guides In Vitro hiPSC Derived Odontoblast Differentiation (iOB).

Over 90% of the U.S. adult population suffers from tooth structure loss due to caries. Most of the mineralized tooth structure is composed of dentin, a material produced and mineralized by ectomesenchyme derived cells known as odontoblasts. Clinicians, scientists, and the general public share the desire to regenerate this missing tooth structure. To bioengineer missing dentin, increased understanding of human tooth development is required. Here we interrogate at the single cell level the signaling interactions that guide human odontoblast and ameloblast development and which determine incisor or molar tooth germ type identity. During human odontoblast development, computational analysis predicts that early FGF and BMP activation followed by later HH signaling is crucial. Application of this sci-RNA-seq analysis generates a differentiation protocol to produce mature hiPSC derived odontoblasts in vitro (iOB). Further, we elucidate the critical role of FGF signaling in odontoblast maturation and its biomineralization capacity using the de novo designed FGFR1/2c isoform specific minibinder scaffolded as a C6 oligomer that acts as a pathway agonist. We find that FGFR1c is upregulated in functional odontoblasts and specifically plays a crucial role in driving odontoblast maturity. Using computational tools, we show on a molecular level how human molar development is delayed compared to incisors. We reveal that enamel knot development is guided by FGF and WNT in incisors and BMP and ROBO in the molars, and that incisor and molar ameloblast development is guided by FGF, EGF and BMP signaling, with tooth type specific intensity of signaling interactions. Dental ectomesenchyme derived cells are the primary source of signaling ligands responsible for both enamel knot and ameloblast development.

Single-cell census of human tooth development enables generation of human enamel.

Tooth enamel secreted by ameloblasts (AMs) is the hardest material in the human body, acting as a shield to protect the teeth. However, the enamel is gradually damaged or partially lost in over 90% of adults and cannot be regenerated due to a lack of ameloblasts in erupted teeth. Here, we use single-cell combinatorial indexing RNA sequencing (sci-RNA-seq) to establish a spatiotemporal single-cell census for the developing human tooth and identify regulatory mechanisms controlling the differentiation process of human ameloblasts. We identify key signaling pathways involved between the support cells and ameloblasts during fetal development and recapitulate those findings in human ameloblast in vitro differentiation from induced pluripotent stem cells (iPSCs). We furthermore develop a disease model of amelogenesis imperfecta in a three-dimensional (3D) organoid system and show AM maturation to mineralized structure in vivo. These studies pave the way for future regenerative dentistry.

Beta-adrenergic signaling accelerates and synchronizes cardiac ryanodine receptor response to a single L-type Ca2+ channel.

As the most prototypical G protein-coupled receptor, beta-adrenergic receptor (betaAR) regulates the pace and strength of heart beating by enhancing and synchronizing L-type channel (LCC) Ca(2+) influx, which in turn elicits greater sarcoplasmic reticulum (SR) Ca(2+) release flux via ryanodine receptors (RyRs). However, whether and how betaAR-protein kinase A (PKA) signaling directly modulates RyR function remains elusive and highly controversial. By using unique single-channel Ca(2+) imaging technology, we measured the response of a single RyR Ca(2+) release unit, in the form of a Ca(2+) spark, to its native trigger, the Ca(2+) sparklet from a single LCC. We found that acute application of the selective betaAR agonist isoproterenol (1 microM, < or = 20 min) increased triggered spark amplitude in an LCC unitary current-independent manner. The increased ratio of Ca(2+) release flux underlying a Ca(2+) spark to SR Ca(2+) content indicated that betaAR stimulation helps to recruit additional RyRs in synchrony. Quantification of sparklet-spark kinetics showed that betaAR stimulation synchronized the stochastic latency and increased the fidelity (i.e., chance of hit) of LCC-RyR intermolecular signaling. The RyR modulation was independent of the increased SR Ca(2+) content. The PKA antagonists Rp-8-CPT-cAMP (100 microM) and H89 (10 microM) both eliminated these effects, indicating that betaAR acutely modulates RyR activation via the PKA pathway. These results demonstrate unequivocally that RyR activation by a single LCC is accelerated and synchronized during betaAR stimulation. This molecular mechanism of sympathetic regulation will permit more fundamental studies of altered betaAR effects in cardiovascular diseases.