Deregulation of amyloid precursor protein (APP) metabolism leads to the production of pathological proteoforms of amyloid-beta peptides, which ultimately form amyloid deposits, a primary pathological feature of Alzheimer's disease (AD). The accumulation of misfolded proteins and alterations in protein degradation systems, such as the ubiquitin-proteasome system, endoplasmic reticulum-associated degradation, and autophagy-lysosomal pathways, also contribute to AD development. The Valosin-Containing Protein AAA-ATPase (p97/VCP) is a crucial regulator of proteostasis, facilitating the clearance of misfolded proteins by the proteasome and other protein degradation systems. Here, we investigated whether VCP influences APP processing. Reducing VCP expression or inhibiting its ATPase activity led to the accumulation of mature, full-length APP in cells, thereby decreasing APP trafficking to the cell surface. Downstream of APP-CTFs secretase processing, p97/VCP modulates APP-CTFs cleavage and degradation via autophagy and endolysosomal-dependent mechanisms. Our findings demonstrate that VCP is involved in APP metabolism at two levels: controlling APP trafficking within the cell secretory pathway and regulating autophagy-dependent degradation of APP-CTFs, suggesting a potential role for VCP in the APP deregulation observed in AD. ### Competing Interest Statement The authors have declared no competing interest. Agence Nationale de la Recherche, https://ror.org/00rbzpz17, ANR-11-LABX-01, ANR-15-CE18-0002 Association France Alzheimer, AAP PFA 2023-6459

Aggregates of hyperphosphorylated tau protein are a hallmark of Alzheimer's disease (AD) and other tauopathies. Sleep disturbances—common in AD—have been associated with altered tau phosphorylation and secretion in both animal models and humans, and insufficient sleep is recognized as a potential risk factor for AD. Moreover, sleep deprivation affects mRNA splicing, polyadenylation, and miRNA-mediated degradation. However, how tau phosphorylation, secretion, and splicing are physiologically regulated across the sleep–wake cycle remains unknown. Here, we combine in vitro, in vivo and clinical methods to investigate whether tau phosphorylation, secretion and splicing are governed by circadian rhythms linked to sleep and body temperature (BT). To elucidate underlying mechanisms, we exposed neuronal cells to the physiological temperatures observed under each condition. We found that tau phosphorylation undergoes sleep-driven circadian variations, as it is hyperphosphorylated during sleep, when BT is lower. Similar changes in tau phosphorylation were reproduced in neuronal cells exposed to temperatures recorded during the sleep–wake cycle. In addition, we reveal a novel pathway by which BT modulates tau secretion, with higher temperature increasing extracellular and circulating tau levels. Tau splicing also varied with temperature, as lower temperatures favored exon 10 exclusion. Finally, in humans, the increase in CSF tau levels observed post-wakefulness correlated with BT increase during wakefulness. Overall, these findings demonstrate that tau phosphorylation, secretion, and splicing follow a circadian pattern primarily regulated by BT and sleep. Given the prevalence of sleep disruptions and thermoregulatory deficits in AD, this study offers new insight into how tau pathology may develop and spread.

ProAKAP4 is identified within the flagellum of spermatozoa in various mammalian species, serving as a structural protein associated with motility parameters. This investigation focuses on the presence of proAKAP4 in donkey sperm, elucidating its localization, molecular characteristics, and its correlation with motility descriptors and mitochondrial membrane potential. Twelve ejaculates from Catalan donkeys were analyzed in this study. The initial steps involved proAKAP4 sequencing and detection through Western blotting and immunofluorescence. Post-thaw assessments were conducted at 0, 1, and 3 h, encompassing proAKAP4 levels, sperm motility analyzed via Computer-Assisted Sperm Analysis (CASA), and mitochondrial membrane potential determined by flow cytometry using the JC-1 stain. The findings reveal that proAKAP4 in donkeys exhibits a characteristic localization at the principal piece of the flagellum, consistent with observations in other mammals. The molecular weight of proAKAP4 is determined to be 100 kDa. Significantly, a positive correlation (p ≤ 0.05) is established between proAKAP4 concentration and both total and progressive motility. The presence of cryoprotectant is associated with a lower proAKAP4 concentration. Notably, proAKAP4 experiences a substantial decrease (p ≤ 0.05) during the initial hour post-thawing. In conclusion, proAKAP4 is identified in donkey sperm, akin to its presence in other mammals. It exhibits a positive correlation with total and progressive motility, its concentration is notably affected by the presence of cryoprotectant with significant consumption observed during the initial hour following thawing. These findings contribute to our understanding of proAKAP4 dynamics in donkey sperm, providing insights that may have implications for semen preservation and reproductive technologies in equids.

ProAKAP4, a precursor of AKAP4 (A-kinase anchor protein) found in the flagellum of mammalian and non-mammalian spermatozoa, serves as a structural protein with established correlations to motility parameters across diverse species. This study aimed to determine the proAKAP4 level evolution in thawed stallion semen over a 3 h period, examining its correlation with motility descriptors and mitochondrial membrane potential. Utilizing sixteen ejaculates from four French warmblood stallions, this study involved maintaining thawed samples at 37 °C for 3 h, conducting proAKAP4 enzyme-linked immunosorbent assays (ELISA), computer-assisted sperm analysis (CASA), and mitochondrial membrane potential by JC-1 probe and flow cytometry at 0, 1, and 3 h post-thawing. The findings indicate significant positive correlations (p ≤ 0.05) between proAKAP4 levels and sperm total or progressive motility at all time points analyzed. Spermatozoa velocity descriptors (VAP, VCL, VSL) and spermatozoa lateral head displacement (ALH) display positive correlations (p ≤ 0.05) with ProAKAP4 at the 0 h post-thawing. ProAKAP4 concentration exhibits no discernible difference between batches with or without a cryoprotectant. Notably, proAKAP4 consumption remains insignificant within the initial hour after thawing but becomes significant (p ≤ 0.05) between 1 and 3 h post-thawing. In summary, proAKAP4 demonstrates positive correlations with total and progressive motility in stallion semen for up to 3 h after thawing, albeit showing a noticeable decrease starting from the first hour post-thawing, indicating a progressive consumption as a result of spermatozoa motile activity.

ProAKAP4, a precursor of AKAP4 (A-kinase anchor protein) found in the flagellum of mammalian and non-mammalian spermatozoa, serves as a structural protein with established correlations to motility parameters across diverse species. This study aimed to determine the proAKAP4 levels evolution in thawed stallion semen over a 3-hour period, examining its correlation with motility descriptors and mitochondrial membrane potential. Utilizing sixteen ejaculates from four French warmblood stallions, the study involved maintaining thawed samples at 37°C for 3 hours, conducting proAKAP4 enzyme-linked immunosorbent assay (ELISA), computer-assisted sperm analysis (CASA), and mitochondrial membrane potential by JC-1 probe and flow cytometry at 0, 1, and 3 hours post-thawing. The findings indicate significant positive correlations (p≤0.05) between proAKAP4 levels and sperm total or progressive motility at all time points analyzed. Spermatozoa velocity descriptors (VAP, VCL, VSL) and spermatozoa lateral head displacement (ALH) display positive correlations (p≤0.05) with ProAKAP4 at the 0-hour post-thawing. ProAKAP4 concentration exhibits no discernible difference between batches with or without cryoprotectant. Notably, proAKAP4 consumption remains insignificant within the initial hour after thawing but becomes significant (p≤0.05) between 1 and 3 hours post-thawing. In summary, proAKAP4 demonstrates positive correlations with total and progressive motility in stallion semen for up to 3 hours after thawing, albeit showing a noticeable decrease starting from the first hour post-thawing, indicating a progressive consumption as a result of spermatozoa motile activity.

Reproduction, Fertility and Development is an international journal publishing original research , review and comment in the fields of reproduction and developmental biology in humans, domestic animals and wildlife

The progress in Alzheimer’s disease (AD) treatment suggests a combined therapeutic approach targeting the two lesional processes of AD, which include amyloid plaques made of toxic Aβ species and neurofibrillary tangles formed of aggregates of abnormally modified Tau proteins. A pharmacophoric design, novel drug synthesis, and structure-activity relationship enabled the selection of a polyamino biaryl PEL24-199 compound. The pharmacologic activity consists of a non-competitive β-secretase (BACE1) modulatory activity in cells. Curative treatment of the Thy-Tau22 model of Tau pathology restores short-term spatial memory, decreases neurofibrillary degeneration, and alleviates astrogliosis and neuroinflammatory reactions. Modulatory effects of PEL24-199 towards APP catalytic byproducts are described in vitro, but whether PEL24-199 can alleviate the Aβ plaque load and associated inflammatory counterparts in vivo remains to be elucidated. We investigated short- and long-term spatial memory, Aβ plaque load, and inflammatory processes in APPSwe/PSEN1ΔE9 PEL24-199 treated transgenic model of amyloid pathology to achieve this objective. PEL24-199 curative treatment induced the recovery of spatial memory and decreased the amyloid plaque load in association with decreased astrogliosis and neuroinflammation. The present results underline the synthesis and selection of a promising polyaminobiaryl-based drug that modulates both Tau and, in this case, APP pathology in vivo via a neuroinflammatory-dependent process.

disease (HD) is an inherited neurodegenerative disorder caused by an expansion of CAG repeats in the Huntingtin (HTT) gene. Accumulating evidence suggests that the microtubule-associated tau pro-tein participates in the pathogenesis of HD. Recently, we have identified changes in tau alternative splicing of exons 2, 3 and 10 in the putamen of HD patients (St-Amour et al, 2018). In this study, we sought to determine whether tau mis-splicing events were equally observed in other brain regions that are less prone to neurodegen-eration. Using Western blot and PCR, we characterized the relationship between MAPT splicing of exons 2, 3 and 10, tauopathy and Htt pathologies, as well as neurodegeneration markers in matching putamen and cortical sam -ples from HD (N = 48) and healthy control (N = 25) subjects. We first show that levels of 4R-tau (exon 10 inclu-sion) isoforms are higher in both the putamen and the cortex of individuals with HD, consistent with earlier findings. On the other hand, higher 0N-tau (exclusion of exons 2 and 3) and lower 1N-tau (exclusion of exon 3) isoforms were seen exclusively in the putamen of HD individuals. Interestingly, investigated splicing factors were deregulated in both regions whereas exon 2 differences coincided with increased tau hyperphosphorylation, aggregation and markers of neurodegeneration. Overall, these results imply a differential regulation of tau exon 2 and exon 10 alternative splicing in HD putamen that could provide a useful biomarker or therapeutic target. This article is part of a Special Issue entitled: SI: The Molecular Bases of Tauopathies. (c) 2022 IBRO. Published by Elsevier Ltd. All rights reserved.

Caffeine is the most widely consumed psychoactive substance in the world. Strikingly, the molecular pathways engaged by its regular consumption remain unclear. We herein addressed the mechanisms associated with habitual (chronic) caffeine consumption in the mouse hippocampus using untargeted orthogonal omics techniques. Our results revealed that chronic caffeine exerts concerted pleiotropic effects in the hippocampus at the epigenomic, proteomic, and metabolomic levels. Caffeine lowered metabolism-related processes (e.g., at the level of metabolomics and gene expression) in bulk tissue, while it induced neuron-specific epigenetic changes at synaptic transmission/plasticity-related genes and increased experience-driven transcriptional activity. Altogether, these findings suggest that regular caffeine intake improves the signal-to-noise ratio during information encoding, in part through fine-tuning of metabolic genes, while boosting the salience of information processing during learning in neuronal circuits.

Reproduction, Fertility and Development is an international journal publishing original research , review and comment in the fields of reproduction and developmental biology in humans, domestic animals and wildlife

Spermatozoa are highly differentiated cells whose ultimate function is fertilization to successfully transfer the male genome. This achievement relies on the expression, localization, organization, and proper functionality of their molecular components. For years, proteomics emerged as a remarkable approach for fertility research to identify specific protein markers related to sperm competency. Such biomarkers, undetected with conventional semen analysis methods, are next-generation tools to assess sperm functionality and predict male fertility. Among them, the proAKAP4 marker is a sperm-specific protein, synthesized as the precursor of AKAP4, highly conserved among mammals and only present in the principal piece of the flagellum. ProAKAP4 entails a disposable stock of AKAP4 to ensure long-lasting sperm motility up to the fecundation site, capacitation, and fertility. By being either converted into mature and active AKAP4 or degraded by proteolysis, proAKAP4 is a stress sensor, acting as a potential gatekeeper to prevent transmission of unfavorable genetic damage to the next generation. Loss or decrease of AKAP4 expression does not affect the number of spermatozoa produced but it impacted sperm motility, viability, and fecundation. A method based on proAKAP4 concentration measurement in a defined number of spermatozoa recently appeared as a simple, reliable, reproducible, robust, and quantitative tool to assess more objectively semen quality and predict male fertility. In this review, we will discuss how fundamental discoveries around the proAKAP4 biomarker provide a yet missing molecular dimension in semen analysis assessments to ensure higher semen quality and reproductive performance in veterinary clinics, zoos, and wild animal reproduction centers.

Alzheimer’s disease (AD) is the leading cause of dementia. While impaired glucose homeostasis has been shown to increase AD risk and pathological loss of tau function, the latter has been suggested to contribute to the emergence of the glucose homeostasis alterations observed in AD patients. However, the links between tau impairments and glucose homeostasis, remain unclear. In this context, the present study aimed at investigating the metabolic phenotype of a new tau knock-in (KI) mouse model, expressing, at a physiological level, a human tau protein bearing the P301L mutation under the control of the endogenous mouse Mapt promoter. Metabolic investigations revealed that, while under chow diet tau KI mice do not exhibit significant metabolic impairments, male but not female tau KI animals under High-Fat Diet (HFD) exhibited higher insulinemia as well as glucose intolerance as compared to control littermates. Using immunofluorescence, tau protein was found colocalized with insulin in the β cells of pancreatic islets in both mouse (WT, KI) and human pancreas. Isolated islets from tau KI and tau knock-out mice exhibited impaired glucose-stimulated insulin secretion (GSIS), an effect recapitulated in the mouse pancreatic β-cell line (MIN6) following tau knock-down. Altogether, our data indicate that loss of tau function in tau KI mice and, particularly, dysfunction of pancreatic β cells might promote glucose homeostasis impairments and contribute to metabolic changes observed in AD.

AbstractBackgroundFew studies to date have attempted to measure serum anti-Müllerian hormone (AMH) levels in adult men, and solid references ranges have not yet been defined in a large cohort.ObjectiveIn this study, we aimed, first, to establish the reference ranges for serum AMH and AMH-to-total testosterone ratio (AMH/tT) in adult males. Second, we investigated the relationship between serum AMH and both reproductive hormones and semen parameters.MethodsThis single-center retrospective study included 578 normozoospermic adult men. Serum AMH concentrations were determined with an automated sandwich chemiluminescent immunoassay.ResultsThe median serum AMH was 43.5 pmol/L. The 2.5th and 97.5th percentile values for serum AMH and AMH/tT were 16.4 and 90.3 pmol/L and 0.45 and 3.43, respectively. AMH was positively correlated with inhibin B and sperm concentration and negatively correlated with age, follicle-stimulating hormone (FSH), and progressive sperm motility. Interestingly, using immunofluorescence, we documented for the first time that AMH type II receptor (AMH-R2) is expressed in ejaculated human spermatozoa and gonadotrophic cells in the postmortem pituitary gland.ConclusionsWe establish a new age-specific reference range for serum AMH and AMH/tT. Moreover, AMH-R2 expression in human spermatozoa and gonadotrophic cells, together with the relationship between serum AMH levels and sperm motility or mean FSH levels, highlight new potential functions of AMH in regulating sperm motility or FSH secretion in adult men.

Alzheimer's disease is a complex and multifactorial disease characterized by extracellular Aβ peptide deposits related to the deregulation of APP metabolism, intracellular aggregation of hyper and abnormally phosphorylated isoforms of Tau proteins, cell death and neuroinflammation. Targeting all these hallmarks at the same time is an interesting strategy for the treatment of this disease. Ezeprogind (AZP2006) is a drug candidate able to correct APP metabolism and interfere with Tau pathology development that is currently in clinical phase 2a for the treatment of tauopathy Progressive Supranuclear Palsy (PSP). In order to decipher the structure-activity relationships, we synthetized 13 analogs and pharmacomodulated different moieties of the scaffold including substitution of the benzimidazole ring and modification of the piperazine central core. APP metabolism was first evaluated with these molecules. Most of them showed no cytotoxicity on SH-SY5Y-APPwt cells and an activity comparable to ezeprogind as reduction of Aβ secretion, increase expression of carboxy-terminal fragments of APP at the micromolar range. Despite major structural differences, most of these analogs showed similar effects on the metabolism of APP. Noteworthy, none of them showed increased efficacy when compared to ezeprogind in vitro. Analogs with different central cores were then tested on primary cortical neurons co-cultured with microglia and injured with Aβ1-42 to analyse Tau metabolism, neuroprotection and neuroinflammation. Together, ezeprogind was shown herein to be the only molecule remaining effective on neuroprotection and neuroinflammation as well as Tau and APP metabolism.

ProAKAP4 is the precursor of AKAP4 (A-kinase Anchor protein 4), the main structural protein of the fibrous sheath of sperm. The amount of proAKAP4 reflects the ability of spermatozoa to maintain the flagellum activity and functionality up to the site of fertilization and is positively correlated with progressive motility in several mammalian species. The aim of this study was to investigate the relationship between proAKAP4 concentration with horse sperm motility descriptors and spermatic motile subpopulations. For this purpose, a total of 48 ejaculates from 13 different stallions were analyzed. Spermatic motility descriptors were obtained by the CASA system, and four motile subpopulations (SP) with specific motility patterns were statistically identified. ProAKAP4 concentrations were evaluated by ELISA. The relationship between motility descriptors of sperm subpopulations and proAKAP4 concentrations was evaluated. Following a hierarchical cluster statistical analysis, ejaculates were divided into two groups according to their proAKAP4 concentrations, either having low proAKAP4 concentrations (5.06–35.61 ng/10M spz; n = 23) or high (39.92–82.23 ng/10M spz; n = 25) proAKAP4 concentrations (p < 0.001). ProAKAP4 concentrations were positively correlated (p < 0.05) with total and progressive motility, as well as with parameters of velocity. ProAKAP4 amount also showed a negative correlation (p < 0.05) with sperm motile subpopulation number 3, which was the subpopulation with the lowest velocity parameters. In conclusion, proAKAP4 concentration in stallion semen positively reflects sperm progressive motility with the functional velocity kinematic descriptors. Concentrations of proAKAP4 higher than 37.77 ng/10M spz were correlated with a very good quality frozen/thawed stallion semen.

Objective To investigate Tau pathology using multimodal biomarkers of neurodegeneration and neurocognition in participants with myotonic dystrophy type 1 (DM1). Methods We recruited twelve participants with DM1 and, for comparison, two participants with Alzheimer’s Disease (AD). Participants underwent cognitive screening and social cognition testing using the Dépistage Cognitif de Québec (DCQ), among other tests. Biomarkers included Tau PET with [18F]-AV-1451, CSF (Aβ, Tau, phospho-Tau), and plasma (Aβ, Tau, Nf-L, GFAP) studies. Results Of the twelve DM1 participants, seven completed the full protocol (Neurocognition 11/12; PET 7/12, CSF 9/12, plasma 12/12). Three DM1 participants were cognitively impaired (CI). On average, CI DM1 participants had lower scores on the DCQ compared to cognitively unimpaired (CU) DM1 participants (75.5/100 vs. 91.4/100) and were older (54 vs. 44 years old) but did not differ in years of education (11.3 vs. 11.1). The majority (6/7) of DM1 participants had no appreciable PET signal. Only one of the CI participants presented with elevated Tau PET SUVR in bilateral medial temporal lobes. This participant was the eldest and most cognitively impaired, and had the lowest CSF Aβ 1-42 and the highest CSF Tau levels, all suggestive of co-existing AD. CSF Tau and phospho-Tau levels were higher in the 3 CI compared to CU DM1 participants, but with a mean value lower than that typically observed in AD. Nf-L and GFAP were elevated in most DM1 participants (9/11 and 8/11, respectively). Finally, CSF phospho-Tau was significantly correlated with plasma Nf-L concentrations. Conclusions and relevance We observed heterogenous cognitive and biomarker profiles in individuals with DM1. While some participants presented with abnormal PET and/or CSF Tau, these patterns were highly variable and only present in a small subset. Although DM1 may indeed represent a non-AD Tauopathy, the Tau-PET tracer used in this study was unable to detect an in vivo Tau DM1 signature in this small cohort. Interestingly, most DM1 participants presented with elevated plasma Nf-L and GFAP levels, suggestive of other, possibly related, central brain alterations which motivate further research. This pioneering study provides novel insights towards the potential relationship between biomarkers and neurocognitive deficits commonly seen in DM1.

Nous avons d’abord cherché à établir l’intervalle de référence pour les concentrations sériques d’AMH chez des hommes adultes. Deuxièmement, nous avons étudié la relation entre les concentrations sériques d’AMH et les gonadotrophines, la testostérone totale ainsi que les paramètres spermatiques. Au total, 578 hommes adultes normozoospermiques ont été inclus dans cette étude monocentrique. Pour les hommes âgés de 20 à 39 ans, les 2,5 e et 97,5 e percentiles des concentrations d’AMH étaient de 18,1–90,9 pmol/L, et pour ceux dont l’âge > 39 ans de 12,3–87,6 pmol/L. Les concentrations sériques d’AMH étaient positivement corrélées avec l’inhibine B et la concentration des spermatozoïdes, et négativement corrélées avec l’âge, la FSH et la mobilité progressive des spermatozoïdes. Ces corrélations persistent après ajustement sur l’âge, les concentrations d’inhibine B et/ou la FSH. En utilisant une approche par immunofluorescence, nous avons documenté pour la première fois que le récepteur d’AMH de type II (AMH-R2) est exprimé dans les spermatozoïdes humains et les cellules gonadotropes de l’hypophyse humaine. De nouveaux intervalles de référence des taux sériques d’AMH spécifiques à l’âge ont été établis. En outre, l’expression de l’AMH-R2 dans les spermatozoïdes et les cellules gonadotropes humaines, ainsi que les corrélations entre les taux sériques d’AMH et la mobilité des spermatozoïdes ou les taux de FSH, mettent la lumière sur de nouvelles potentielles fonctions de l’AMH dans la régulation de la motilité spermatique ainsi que la sécrétion de FSH chez les hommes adultes.