CRHR1 antagonist alleviated depression-like behavior by downregulating p62 in a rat model of post-stroke depression.

Post-stroke depression (PSD) is a complication of cerebrovascular disease, which can increase mortality after stroke. CRH is one of the main signaling peptides released after activation of the hypothalamic-pituitary-adrenal (HPA) axis in response to stress. It affects synaptic plasticity by regulating inflammation, oxidative stress and autophagy in the central nervous system. And the loss of spines exacerbates depression-like behavior. Therefore, synaptic deficits induced by CRH may be related to post-stroke depression. However, the underlying mechanism remains unclear. The Keap1-Nrf2 complex is one of the core components of the antioxidant response. As an autophagy associated protein, p62 participates in the Keap1-NrF2 pathway through its Keap1 interaction domain. Oxidative stress is involved in the feedback regulation between Keap1-Nrf2 pathway and p62.However, whether the relationship between CRH and the Keap1-Nrf2-p62 pathway is involved in PSD remains unknown. This study found that serum levels of CRH in 22 patients with PSD were higher than those in healthy subjects. We used MCAO combined with CUMS single-cage SD rats to establish an animal model of PSD. Animal experiments showed that CRHR1 antagonist prevented synaptic loss in the hippocampus of PSD rats and alleviated depression-like behavior. CRH induced p62 accumulation in the prefrontal cortex of PSD rats through CRHR1. CRHR1 antagonist inhibited Keap1-Nrf2-p62 pathway by attenuating oxidative stress. In addition, we found that abnormal accumulation of p62 induces PSD. It alleviates depression-like behavior by inhibiting the expression of p62 and promoting the clearance of p62 in PSD rats. These findings can help explore the pathogenesis of PSD and design targeted treatments for PSD.

DAPK1 mediates cognitive dysfunction and neuronal apoptosis in PSD rats through the ERK/CREB/BDNF signaling pathway.

Post-stroke depression (PSD) is one of the most common mental sequelae after a stroke and can damage the brain. Although PSD has garnered increasing attention in recent years, the precise mechanism remains unclear. Studies have indicated that the expression of DAPK1 is elevated in various neurodegenerative conditions, including depression, ischemic stroke, and Alzheimer's disease. However, the specific molecular mechanism of DAPK1-mediated cognitive dysfunction and neuronal apoptosis in PSD rats is unclear. In this study, we established a rat model of PSD, and then assessed depression-like behaviors and cognitive dysfunction in rats using behavioral tests. In addition, we detected neuronal apoptosis and analyzed the expression of DAPK1 protein and proteins related to the ERK/CREB/BDNF signaling pathway. The findings revealed that MCAO combined with CUMS can induce more severe depression-like behaviors and cognitive dysfunction in rats, while overexpression of DAPK1 may hinder the downstream ERK/CREB/BDNF signaling pathways, resulting in neuronal loss and exacerbation of brain tissue damage. In this study, we will focus on DAPK1 and explore its role in PSD.

HSD17B1 Compensates for HSD17B3 Deficiency in Fetal Mouse Testis but Not in Adults.

Hydroxysteroid (17ß) dehydrogenase (HSD17B) enzymes convert 17-ketosteroids to 17beta-hydroxysteroids, an essential step in testosterone biosynthesis. Human XY individuals with inactivating HSD17B3 mutations are born with female-appearing external genitalia due to testosterone deficiency. However, at puberty their testosterone production reactivates, indicating HSD17B3-independent testosterone synthesis. We have recently shown that Hsd17b3 knockout (3-KO) male mice display a similar endocrine imbalance, with high serum androstenedione and testosterone in adulthood, but milder undermasculinization than humans. Here, we studied whether HSD17B1 is responsible for the remaining HSD17B activity in the 3-KO male mice by generating a Ser134Ala point mutation that disrupted the enzymatic activity of HSD17B1 (1-KO) followed by breeding Hsd17b1/Hsd17b3 double-KO (DKO) mice. In contrast to 3-KO, inactivation of both HSD17B3 and HSD17B1 in mice results in a dramatic drop in testosterone synthesis during the fetal period. This resulted in a female-like anogenital distance at birth, and adult DKO males displayed more severe undermasculinization than 3-KO, including more strongly reduced weight of seminal vesicles, levator ani, epididymis, and testis. However, qualitatively normal spermatogenesis was detected in adult DKO males. Furthermore, similar to 3-KO mice, high serum testosterone was still detected in adult DKO mice, accompanied by upregulation of various steroidogenic enzymes. The data show that HSD17B1 compensates for HSD17B3 deficiency in fetal mouse testis but is not the enzyme responsible for testosterone synthesis in adult mice with inactivated HSD17B3. Therefore, other enzymes are able to convert androstenedione to testosterone in the adult mouse testis and presumably also in the human testis.

The histone lysine methyltransferase MLL1 regulates the activation and functional specialization of regulatory T cells.

The activation and specialization of regulatory T cells (Tregs) are crucial for maintaining immune self-tolerance; however, the regulation of these processes by histone modifications is not fully understood. Here, we show that T cell-specific deletion of the lysine methyltransferase MLL1 results in a spontaneous lymphocyte proliferation phenotype in aged mice without disturbing the development of conventional T cells and Tregs. Treg-specific MLL1 ablation leads to a systemic autoimmune disease associated with Treg dysfunction. Moreover, RNA sequencing demonstrates that the induction of multiple genes involved in Treg activation, functional specialization, and tissue immigration is defective in MLL1-deficient Tregs. This dysregulation is associated with defects in H3K4 trimethylation at these genes' transcription start sites. Finally, using a T-bet fate-mapping mouse system, we determine that MLL1 is required to establish stable Th1-type Tregs. Thus, MLL1 is essential in optimal Treg function by providing a coordinated chromatin context for activation and specialization.

FTO Positively Regulates Odontoblastic Differentiation via SMOC2 in Human Stem Cells from the Apical Papilla under Inflammatory Microenvironment.

Odontoblastic differentiation of human stem cells from the apical papilla (hSCAPs) is crucial for continued root development and dentin formation in immature teeth with apical periodontitis (AP). Fat mass and obesity-associated protein (FTO) has been reported to regulate bone regeneration and osteogenic differentiation profoundly. However, the effect of FTO on hSCAPs remains unknown. This study aimed to identify the potential function of FTO in hSCAPs' odontoblastic differentiation under normal and inflammatory conditions and to investigate its underlying mechanism preliminarily. Histological staining and micro-computed tomography were used to evaluate root development and FTO expression in SD rats with induced AP. The odontoblastic differentiation ability of hSCAPs was assessed via alkaline phosphatase and alizarin red S staining, qRT-PCR, and Western blotting. Gain- and loss-of-function assays and online bioinformatics tools were conducted to explore the function of FTO and its potential mechanism in modulating hSCAPs differentiation. Significantly downregulated FTO expression and root developmental defects were observed in rats with AP. FTO expression notably increased during in vitro odontoblastic differentiation of hSCAPs, while lipopolysaccharide (LPS) inhibited FTO expression and odontoblastic differentiation. Knockdown of FTO impaired odontoblastic differentiation, whereas FTO overexpression alleviated the inhibitory effects of LPS on differentiation. Furthermore, FTO promoted the expression of secreted modular calcium-binding protein 2 (SMOC2), and the knockdown of SMOC2 in hSCAPs partially attenuated the promotion of odontoblastic differentiation mediated by FTO overexpression under LPS-induced inflammation. This study revealed that FTO positively regulates the odontoblastic differentiation ability of hSCAPs by promoting SMOC2 expression. Furthermore, LPS-induced inflammation compromises the odontoblastic differentiation of hSCAPs by downregulating FTO, highlighting the promising role of FTO in regulating hSCAPs differentiation under the inflammatory microenvironment.

Recent progress in nanomaterials for bacteria-related tumor therapy.

Many studies suggest that tumor microbiome closely relates to the oncogenesis and anti-tumor responses in multiple cancer types (e.g., colorectal cancer (CRC), breast cancer, lung cancer and pancreatic cancer), thereby raising an emerging research area of bacteria-related tumor therapy. Nanomaterials have long been used for both cancer and bacterial infection treatment, holding great potential for bacteria-related tumor therapy. In this review, we summarized recent progress in nanomaterials for bacteria-related tumor therapy. We focus on the types and mechanisms of pathogenic bacteria in the development and promotion of cancers and emphasize how nanomaterials work. We also briefly discuss the design principles and challenges of nanomaterials for bacteria-related tumor therapy. We hope this review can provide some insights into this emerging and rapidly growing research area.

Embigin deficiency leads to delayed embryonic lung development and high neonatal mortality in mice.

Embigin (Gp70), a receptor for fibronectin and an ancillary protein for monocarboxylate transporters, is known to regulate stem cell niches in sebaceous gland and bone marrow. Here, we show that embigin expression is at high level during early mouse embryogenesis and that embigin is essential for lung development. Markedly increased neonatal mortality of Emb-/- mice can be explained by the compromised lung maturation: in Emb-/- mice (E17.5) the number and the size of the small airways and distal airspace are significantly smaller, there are fewer ATI and ATII cells, and the alkaline phosphatase activity in amniotic fluid is lower. Emb-/- lungs show less peripheral branching already at E12.5, and embigin is highly expressed in lung primordium. Thus, embigin function is essential at early pseudoglandular stage or even earlier. Furthermore, our RNA-seq analysis and Ki67 staining results support the idea that the development of Emb-/- lungs is rather delayed than defected.

Characterization of CD8+ T cells in immune-privileged organs of ZIKV-infected Ifnar1-/- mice.

Zika virus (ZIKV) infection caused neurological complications and male infertility, leading to the accumulation of antigen-specific immune cells in immune-privileged organs (IPOs). Thus, it is important to understand the immunological responses to ZIKV in IPOs. We extensively investigated the ZIKV-specific T cell immunity in IPOs in Ifnar1-/- mice, based on an immunodominant epitope E294-302 tetramer. The distinct kinetics and functions of virus-specific CD8+ T cells infiltrated into different IPOs were characterized, with late elevation in the brain and spinal cord. Single epitope E294-302-specific T cells can account for 20-60% of the total CD8+ T cells in the brain, spinal cord, and testicle and persist for at least 90 days in the brain and spinal cord. The E294-302-specific TCRαßs within the IPOs are featured with the majority of clonotypes utilizing TRAV9N-3 paired with diverse TRBV chains, but with distinct αß paired clonotypes in 7 and 30 days post-infection. Specific chemokine receptors, Ccr2 and Ccr5, were selectively expressed in the E294-302-specific CD8+ T cells within the brain and testicle, indicating an IPO-oriented migration of virus-specific CD8+ T cells after infection. Overall, this study adds to the understanding of virus-specific CD8+ T cell responses for controlling and clearing ZIKV infection in IPOs.IMPORTANCEThe immune-privileged organs (IPOs), such as the central nervous system and testicles, presented pathogenicity and inflammation after Zika virus (ZIKV) infection with infiltrated CD8+ T cells. Our data show that CD8+ T cells keep up with virus increases and decreases in immune-privileged organs. Furthermore, our study provides the first ex vivo comparative analyses of the composition and diversity related to TCRα/ß clonotypes across anatomical sites and ZIKV infection phases. We show that the vast majority of TCRα/ß clonotypes in tissues utilize TRAV9N-3 with conservation. Specific chemokine expression, including Ccr2 and Ccr5, was found to be selectively expressed in the E294-302-specific CD8+ T cells within the brain and testicle, indicating an IPO-oriented migration of the virus-specific CD8+ T cells after the infection. Our study adds insights into the anti-viral immunological characterization and chemotaxis mechanism of virus-specific CD8+ T cells after ZIKV infection in different IPOs.

Co3O4/NiCo2O4 heterojunction as oxygen evolution reaction catalyst for efficient luminol anode electrochemiluminescence.

Luminol has garnered significant attention from analysts as one of the most effective and commonly used electrochemiluminescence (ECL) reagents. However, the efficient luminescence of luminol anode is limited by the excitation of various reactive oxygen species (ROS). Typically, ROS are generated through co-reactive reagents and dissolved oxygen. Unfortunately, the former suffers from two drawbacks, namely biotoxicity and instability, while the latter cannot offer sufficient oxygen due to its limited solubility in aqueous solutions. Consequently, a low decomposition rate is usually obtained, leading to insufficient ROS. Therefore, there is an urgent need to develop efficient luminol anode systems. This study focuses on the use of zeolitic imidazolate framework-67 (ZIF-67) as a template, employing a controlled chemical etching method to create a ZIF-67/Ni-Co-layered double hydroxide (LDH). The intermediate composite is then annealed in air, resulting in the formation of a Co3O4/NiCo2O4 double-shelled nanobox (DSNB) heterostructure. Due to its structural advantages, the DSNB exhibits excellent electrocatalytic performance in the oxygen evolution reaction (OER). Furthermore, it was found that both the intermediates and products of OER can directly participate in the luminol chemiluminescence process, ultimately resulting in a 700-fold increase in the electrochemiluminescence (ECL) signal compared to an equal molar concentration of luminol solution. This work not only establishes the OER-mediated ECL system but also deepens the understanding of the relationship between ROS and luminol, providing a new pathway to study the luminol anodic ECL luminescence system.

High-frequency repetitive transcranial magnetic stimulation improves depressive-like behaviors in CUMS-induced rats by modulating astrocyte GLT-1 to reduce glutamate toxicity.

Impaired glutamate recycling plays an important role in the pathophysiology of depression, and it has been demonstrated that glutamate transporter-1 (GLT-1) on astrocytes is involved in glutamate uptake. Studies have shown that repetitive transcranial magnetic stimulation (rTMS) is effective in treating depression, however, the exact mechanism of rTMS treatment remains unclear. Here, we used a chronic unpredictable mild stress (CUMS) protocol to induce depression-like behaviors in rats followed by rTMS treatment. Behavioral assessment was primarily through SPT, FST, OFT and body weight. Histological analysis focused on GFAP and GLT-1 expression, synaptic plasticity, apoptosis and PI3K/Akt/CREB pathway-related proteins. The results showed that rTMS treatment increased sucrose preference, improved locomotor activity, shortened immobility time as well as increased body weight. And rTMS intervention reversed the elevated glutamate concentration in the hippocampus of CUMS rats using an ELISA kit. Moreover, rTMS ameliorated the reduction in GFAP and GLT-1 expression, alleviated the decrease in BDNF, PSD95 and synapsin-1 expression, also reversed the expression levels of BAX and Bcl2 in the hippocampus of CUMS-induced rats. Moreover, rTMS also increased the protein phosphorylation level of PI3K/Akt/CREB pathway. These results suggest that rTMS treatment ameliorates depression-like behaviors in the rat model by reversing the reduction of GLT-1 on astrocytes and reducing glutamate accumulation in the synaptic cleft, which in turn ameliorates synaptic plasticity damage and neuronal apoptosis. The regulation of GLT-1 by rTMS may be through the PI3K/Akt/CREB pathway.

Effect of plastic mulch residue on plant growth performance and soil properties.

Plastic mulch is widely utilized for weed control, temperature regulation, soil erosion prevention, disease management, and soil structure improvement, ultimately enhancing crop quality and yield. However, a significant issue with conventional plastic mulches is their low recycling rates, which can cause plastic residue to build up, thereby damaging soil quality and reducing crop yield. The emergence of biodegradable films offers a promising solution to mitigate this issue and reduce soil pollution. However, its potential effects on soil properties and plant performance remain unclear. In this study, low-density polyethylene (LDPE) and poly (butylene succinate-co-butylene adipate) (PBSA) were used to observe the effect of plastic mulch residues on soil properties and plant growth performance via potting experiment. Additionally, the interaction effects of compost and biochar as soil amendments with plastic mulch residues were also evaluated. The result of this study revealed that the type of plastic significantly affected the total nitrogen and magnesium uptake; however, the morphological traits of the tested plant (Japanese mustard spinach) were not significantly affected. The addition of compost and biochar led to a significant increase in both shoot and total dry weight of the plant, indicating a positive effect on its growth. The results of the two-way ANOVA indicated a significant influence of plastic type on dissolved phosphate (PO43-) levels and soil dehydrogenase activity (DHA). The interaction effect (plastic type with soil amendment) was statistically significant only for soil DHA. Neither plastic mulch residues nor soil amendments significantly affected other soil chemical properties. However, long-term experiments to systematically investigate the long-term effects of plastic residues are necessary.

Integrated Analysis of the Effects of Cecal Microbiota and Serum Metabolome on Market Weights of Chinese Native Chickens.

The gut microbiota plays an important role in the physiological activities of the host and affects the formation of important economic traits in livestock farming. The effects of cecal microbiota on chicken weights were investigated using the Guizhou yellow chicken as a model. Experimental cohorts from chickens with high- (HC, n = 16) and low-market-weights (LC, n = 16) were collected. Microbial 16S rRNA gene sequencing and non-targeted serum metabolome data were integrated to explore the effect and metabolic mechanism of cecal microbiota on market weight. The genera Lachnoclostridium, Alistipes, Negativibacillus, Sellimonas, and Ruminococcus torques were enriched in the HC group, while Phascolarctobacterium was enriched in the LC group (p < 0.05). Metabolomic analysis determined that pantothenic acid (vitamin B5), luvangetin (2H-1-benzopyran-6-acrylic acid), and menadione (vitamin K3) were significantly higher in HC serum, while beclomethasone dipropionate (a glucocorticoid) and chlorophene (2-benzyl-4-chlorophenol) were present at higher levels in the LC group. The microbes enriched in HC were significantly positively correlated with metabolites, including pantothenic acid and menadione, and negatively correlated with beclomethasone dipropionate and chlorophene. These results indicated that specific cecal bacteria in Guizhou yellow chickens alter the host metabolism and growth performance. This study provides a reference for revealing the mechanism of cecal microbe actions that affect chicken body weight.

The splicing isoform Foxp3Δ2 differentially regulates tTreg and pTreg homeostasis.

Foxp3 is the master transcription factor for regulatory T cells (Tregs). Alternative splicing of human Foxp3 results in the expression of two isoforms: the full length and an exon 2-deleted protein. Here, AlphaFold2 predictions and in vitro experiments demonstrate that the N-terminal domain of Foxp3 inhibits DNA binding by moving toward the C terminus and that this movement is mediated by exon 2. Consequently, we find that Foxp3Δ2-bearing thymus-derived Tregs (tTregs) in the peripheral lymphoid organ are less sensitive to T cell receptor (TCR) stimulation due to the enhanced binding of Foxp3Δ2 to the Batf promoter and are hyporesponsive to interleukin-2 (IL-2). In contrast, among RORγt+ peripherally induced Tregs (pTregs) in the large intestine, Foxp3Δ2 pTregs express many more RORγt-related genes, conferring a competitive advantage. Together, our results reveal that alternative splicing of exon 2 generates an active form of Foxp3, which plays a differential role in regulating tTreg and pTreg homeostasis.

Preparation of oxidized acetylene black by high-temperature calcination for luminol efficient cathodic electrochemiluminescence.

The improvement of electrochemiluminescence (ECL) intensity in luminol, a classic electrochemiluminescent material, remains a controversial topic. In this study, synthesis of acetylene black oxide (ACETO) through simple air annealing was successful in introducing oxygen-containing groups and defects, which can act as active sites for the oxygen reduction reaction (ORR) and exhibit excellent catalytic activity. By introducing the two-electron (2e-) ORR into the cathode ECL system of luminol, integration of ACETO and luminol allows for in situ generation of dissolved oxygen into reactive oxygen species (ROS), thereby enhancing the ECL intensity of luminol. It is worth noting that iron-nitrogen-carbon (FeNC), as a secondary antibody (Ab2) label, can catalyze the decomposition of H2O2, the product of 2e- ORR, into ROS to achieve ECL amplification. Alpha-fetoprotein (AFP), an important tumor marker, was successfully detected with a detection limit of 0.01 pg/mL, indicating that this ECL signal amplification strategy has broad application prospects in biological analysis.

Emerging Roles of YAP/TAZ in Tooth and Surrounding: from Development to Regeneration.

Yes associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are ubiquitous transcriptional co-activators that control organ development, homeostasis, and tissue regeneration. Current in vivo evidence suggests that YAP/TAZ regulates enamel knot formation during murine tooth development, and is indispensable for dental progenitor cell renewal to support constant incisor growth. Being a critical sensor for cellular mechano-transduction, YAP/TAZ lays at the center of the complex molecular network that integrates mechanical cues from the dental pulp chamber and surrounding periodontal tissue into biochemical signals, dictating in vitro cell proliferation, differentiation, stemness maintenance, and migration of dental stem cells. Moreover, YAP/TAZ-mediated cell-microenvironment interactions also display essential regulatory roles during biomaterial-guided dental tissue repair and engineering in some animal models. Here, we review recent advances in YAP/TAZ functions in tooth development, dental pulp, and periodontal physiology, as well as dental tissue regeneration. We also highlight several promising strategies that harness YAP/TAZ activation for promoting dental tissue regeneration.

Case report: Compound heterozygous nonsense PCDH15 variant and a novel deep-intronic variant in a Chinese child with profound hearing loss.

BACKGROUND: Usher syndrome is a condition characterized by partial or total hearing loss and progressive pigmentary retinopathy. Usher syndrome type 1F is caused by biallelic loss-of-function variants in Protocadherin 15 (PCDH15), which encodes the PCDH15 protein that plays an important role in the morphogenesis and cohesion of stereocilium bundles and retinal photoreceptor cell maintenance and function. METHODS: We report a child with bilateral nonsyndromic sensorineural hearing loss who received an inconclusive diagnosis based on clinical gene panel testing, which identified a paternal heterozygous nonsense variant (NM_033056.4: c.733C>T, p.R245*) in PCDH15. This variant has been described as a founder variant in the Ashkenazi Jewish population. RESULTS: A novel deep-intronic variant (NM_033056.4: c.705+3767_705+3768del) inherited from the patient's mother was identified by trio-based whole-genome sequencing (WGS). A minigene splicing assay revealed that c.705+3767_705+3768del results in aberrant retention of 50 or 68 bp of intron 7. CONCLUSION: Our genetic test results provided precise genetic counseling and prenatal diagnosis for this family, and our findings highlight the power of WGS for detecting deep-intronic variants in patients with undiagnosed rare diseases. Additionally, this case expands the variant spectrum of the PCDH15 gene and our results support the extremely low carrier frequency of c.733C>T in the Chinese population.

MSFFAL: Few-Shot Object Detection via Multi-Scale Feature Fusion and Attentive Learning.

Few-shot object detection (FSOD) is proposed to solve the application problem of traditional detectors in scenarios lacking training samples. The meta-learning methods have attracted the researchers' attention for their excellent generalization performance. They usually select the same class of support features according to the query labels to weight the query features. However, the model cannot possess the ability of active identification only by using the same category support features, and feature selection causes difficulties in the testing process without labels. The single-scale feature of the model also leads to poor performance in small object detection. In addition, the hard samples in the support branch impact the backbone's representation of the support features, thus impacting the feature weighting process. To overcome these problems, we propose a multi-scale feature fusion and attentive learning (MSFFAL) framework for few-shot object detection. We first design the backbone with multi-scale feature fusion and channel attention mechanism to improve the model's detection accuracy on small objects and the representation of hard support samples. Based on this, we propose an attention loss to replace the feature weighting module. The loss allows the model to consistently represent the objects of the same category in the two branches and realizes the active recognition of the model. The model no longer depends on query labels to select features when testing, optimizing the model testing process. The experiments show that MSFFAL outperforms the state-of-the-art (SOTA) by 0.7-7.8% on the Pascal VOC and exhibits 1.61 times the result of the baseline model in MS COCO's small objects detection.

Dissecting the KNDy hypothesis: KNDy neuron-derived kisspeptins are dispensable for puberty but essential for preserved female fertility and gonadotropin pulsatility.

BACKGROUND: Kiss1 neurons in the hypothalamic arcuate-nucleus (ARC) play key roles in the control of GnRH pulsatility and fertility. A fraction of ARC Kiss1 neurons, termed KNDy, co-express neurokinin B (NKB; encoded by Tac2). Yet, NKB- and Kiss1-only neurons are also found in the ARC, while a second major Kiss1-neuronal population is present in the rostral hypothalamus. The specific contribution of different Kiss1 neuron sub-sets and kisspeptins originating from them to the control of reproduction and eventually other bodily functions remains to be fully determined. METHODS: To tease apart the physiological roles of KNDy-born kisspeptins, conditional ablation of Kiss1 in Tac2-expressing cells was implemented in vivo. To this end, mice with Tac2 cell-specific Kiss1 KO (TaKKO) were generated and subjected to extensive reproductive and metabolic characterization. RESULTS: TaKKO mice displayed reduced ARC kisspeptin content and Kiss1 expression, with greater suppression in females, which was detectable at infantile-pubertal age. In contrast, Tac2/NKB levels were fully preserved. Despite the drop of ARC Kiss1/kisspeptin, pubertal timing was normal in TaKKO mice of both sexes. However, young-adult TaKKO females displayed disturbed LH pulsatility and sex steroid levels, with suppressed basal LH and pre-ovulatory LH surges, early-onset subfertility and premature ovarian insufficiency. Conversely, testicular histology and fertility were grossly conserved in TaKKO males. Ablation of Kiss1 in Tac2-cells led also to sex-dependent alterations in body composition, glucose homeostasis, especially in males, and locomotor activity, specifically in females. CONCLUSIONS: Our data document that KNDy-born kisspeptins are dispensable/compensable for puberty in both sexes, but required for maintenance of female gonadotropin pulsatility and fertility, as well as for adult metabolic homeostasis. SIGNIFICANCE STATEMENT: Neurons in the hypothalamic arcuate nucleus (ARC) co-expressing kisspeptins and NKB, named KNDy, have been recently suggested to play a key role in pulsatile secretion of gonadotropins, and hence reproduction. However, the relative contribution of this Kiss1 neuronal-subset, vs. ARC Kiss1-only and NKB-only neurons, as well as other Kiss1 neuronal populations, has not been assessed in physiological settings. We report here findings in a novel mouse-model with elimination of KNDy-born kisspeptins, without altering other kisspeptin compartments. Our data highlights the heterogeneity of ARC Kiss1 populations and document that, while dispensable/compensable for puberty, KNDy-born kisspeptins are required for proper gonadotropin pulsatility and fertility, specifically in females, and adult metabolic homeostasis. Characterization of this functional diversity is especially relevant, considering the potential of kisspeptin-based therapies for management of human reproductive disorders.

Melatonin-mediated malic enzyme 2 orchestrates mitochondrial fusion and respiratory functions to promote odontoblastic differentiation during tooth development.

Tooth development is a complex process that is tightly controlled by circadian rhythm. Melatonin (MT) is a major hormonal regulator of the circadian rhythm, and influences dentin formation and odontoblastic differentiation during tooth development; however, the underlying mechanism remains elusive. This study investigated how MT regulates odontoblastic differentiation, with a special focus on its regulation of mitochondrial dynamics. In rat dental papilla cells (DPCs), we found that MT promotes odontoblastic differentiation concurrently with enhanced mitochondrial fusion, while disruption of mitochondrial fusion by depleting optic atrophy 1 (OPA1) impairs MT-mediated differentiation and mitochondrial respiratory functions. Through RNA sequencing, we discovered that MT significantly upregulated malic enzyme 2 (ME2), a mitochondrial NAD(P)+ -dependent enzyme, and identified ME2 as a critical MT downstream effector that orchestrates odontoblastic differentiation, mitochondrial fusion, and respiration functions. By detecting the spatiotemporal expression of ME2 in developing tooth germs, and using tooth germ reconstituted organoids, we also provided in vivo and ex vivo evidence that ME2 promotes dentin formation, indicating a possible involvement of ME2 in MT-modulated tooth development. Collectively, our findings offer novel understandings regarding the molecular mechanism by which MT affects cell differentiation and organogenesis, meanwhile, the critical role of ME2 in MT-regulated mitochondrial functions is also highlighted.