Although APP metabolism is being intensively investigated, a large fraction of its modulators is yet to be characterized. In this context, we combined two genome-wide high-content screenings to ...assess the functional impact of miRNAs and genes on APP metabolism and the signaling pathways involved. This approach highlighted the involvement of FERMT2 (or Kindlin-2), a genetic risk factor of Alzheimer's disease (AD), as a potential key modulator of axon guidance, a neuronal process that depends on the regulation of APP metabolism. We found that FERMT2 directly interacts with APP to modulate its metabolism, and that FERMT2 underexpression impacts axonal growth, synaptic connectivity, and long-term potentiation in an APP-dependent manner. Last, the rs7143400-T allele, which is associated with an increased AD risk and localized within the 3'UTR of FERMT2, induced a downregulation of FERMT2 expression through binding of miR-4504 among others. This miRNA is mainly expressed in neurons and significantly overexpressed in AD brains compared to controls. Altogether, our data provide strong evidence for a detrimental effect of FERMT2 underexpression in neurons and insight into how this may influence AD pathogenesis.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by changes in cognitive and behavioral functions. With the exception or rare mutations in PSEN and APP genes causing ...early-onset autosomal dominant AD (EOADAD), little is known about the genetic factors that underlie the vast majority (>95%) of early onset AD (EOAD) cases. We have previously identified copy number variations (CNVs) in microRNA genes in patients with EOAD, including a duplication of the MIR-138-2 gene. Overexpression of miR-138 in cultured cells increased Aβ production and tau phosphorylation, similar to what is seen in AD brain. In this study, we sought to determine if miR-138 overexpression could recapitulate certain features of disease
in non-transgenic mice. A mild overexpression of pre-miR-138 in the brain of C57BL/6J wildtype mice altered learning and memory in a novel object recognition test and in the Barnes Maze. Increased levels of anxiety were also observed in the open-field test. MiR-138 upregulation
caused an increase in endogenous Aβ42 production as well as changes in synaptic and inflammation markers. Tau expression was significantly lower with no overt effects on phosphorylation. We finally observed that Sirt1, a direct target of miR-138 involved in Aβ production, learning and memory as well as anxiety, is decreased following miR-138 overexpression. In sum, this study further strengthens a role for increased gene dosage of MIR-138-2 gene in modulating AD risk, possibly by acting on different biological pathways. Further studies will be required to better understand the role of CNVs in microRNA genes in AD and related neurodegenerative disorders.
In preclinical research on Alzheimer's disease and related tauopathies, tau phosphorylation analysis is routinely employed in both cellular and animal models. However, recognizing the sensitivity of ...tau phosphorylation to various extrinsic factors, notably temperature, is vital for experimental accuracy. Hypothermia can trigger tau hyperphosphorylation, while hyperthermia leads to its dephosphorylation. Nevertheless, the rapidity of tau phosphorylation in response to unintentional temperature variations remains unknown. In cell cultures, the most significant temperature change occurs when the cells are removed from the incubator before harvesting, and in animal models, during anesthesia prior to euthanasia. In this study, we investigate the kinetics of tau phosphorylation in N2a and SH-SY5Y neuronal cell lines, as well as in mice exposed to anesthesia. We observed changes in tau phosphorylation within the few seconds upon transferring cell cultures from their 37°C incubator to room temperature conditions. However, cells placed directly on ice post-incubation exhibited negligible phosphorylation changes. In vivo, isoflurane anesthesia rapidly resulted in tau hyperphosphorylation within the few seconds needed to lose the pedal withdrawal reflex in mice. These findings emphasize the critical importance of preventing temperature variation in researches focused on tau. To ensure accurate results, we recommend avoiding anesthesia before euthanasia and promptly placing cells on ice after removal from the incubator. By controlling temperature fluctuations, the reliability and validity of tau phosphorylation studies can be significantly enhanced.
In the past decade, several groups have reported that microRNAs (miRNAs) can participate in the regulation of tau protein at different levels, including its expression, alternative splicing, ...phosphorylation, and aggregation. These observations are significant, since the abnormal regulation and deposition of tau is associated with nearly 30 neurodegenerative disorders. Interestingly, miRNA profiles go awry in tauopathies such as Alzheimer's disease, progressive supranuclear palsy, and frontotemporal dementia. Understanding the role and impact of miRNAs on tau biology could therefore provide important insights into disease risk, diagnostics, and perhaps therapeutics. In this Perspective article, we discuss recent advances in miRNA research related to tau. While proof-of-principle studies hold promise, physiological validation remains limited. To help fill this gap, we describe herein a pure tauopathy mouse model deficient for the miR-132/212 cluster. This miRNA family is strongly downregulated in human tauopathies and shown to regulate tau
in vitro
and
in vivo
. No significant differences in survival, motor deficits or body weight were observed in PS19 mice lacking miR-132/212. Age-specific effects were seen on tau expression and phosphorylation but not aggregation. Moreover, various miR-132/212 targets previously implicated in tau modulation were unaffected (GSK-3β, Foxo3a, Mapk1, p300) or, unexpectedly, reduced (Mapk3, Foxo1, p300, Calpain 2) in miR-132/212-deficient PS19 mice. These observations highlight the challenges of miRNA research in living models, and current limitations of transgenic tau mouse models lacking functional miRNA binding sites. Based on these findings, we finally recommend different strategies to better understand the role of miRNAs in tau physiology and pathology.
Propagation of hyperphosphorylated and aggregated tau protein is a hallmark of Alzheimer’s disease (AD). Previously, we demonstrated that tau phosphorylation is inversely correlated with body ...temperature (BT) variations during the sleep/wake cycle. Tau is hyperphosphorylated during sleep (when BT is lower), compared to wakefulness (when BT is higher). Interestingly, it has been shown that tau in ISF and CSF is increased during wakefulness, suggesting increased secretion. We thus hypothesized that tau secretion might be regulated by BT during the sleep/wake cycle.
Bisphenol A (BPA) is an industrial chemical widely used in the production of polycarbonate and epoxy resins. Identified as an endocrine-disrupting chemical (EDC), BPA is a matter of existing or ...ongoing restrictive regulations and then is increasingly being replaced by other analogues used as BPA’s substitutes. Human biomonitoring studies focusing on both BPA and emerging related analogues consequently appear as a requirement either for documenting the efficiency of regulatory actions toward BPA and for fuelling incoming risk assessment studies toward BPA’s substitutes. In particular, the increasing concern about the late effects consecutive to early exposures naturally identify human breast milk as a target biological matrix of interest for priority exposure assessment focused on critical sub-populations such as pregnant women, fetuses, and/or newborns. In this context, an accurate and sensitive analytical method based on gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) was developed for the quantification of 18 “BPA-like” compounds in breast milk samples at trace levels (<0.05 μg kg
−1
). The method includes a preliminary protein precipitation step followed by two successive solid-phase extraction (SPE) stages. Quantification of the targeted compounds was achieved according to the isotopic dilution method using
13
C
12
-BPA as internal standard. The method was validated according to current EU guidelines and criteria. Linearity (
R
2
) was better than 0.99 for each molecule within the concentration range 0–5 μg kg
−1
. The detection and quantification limits ranged from 0.001 to 0.030 μg kg
−1
and from 0.002 to 0.050 μg kg
−1
, respectively. The analytical method was successfully applied to the first set of human breast milk samples (
n
= 30) originating from French women in the Region Pays-de-la-Loire. The measured levels of BPA were found in the <LOQ–1.16 μg kg
−1
range. BPS was detected in only one sample at 0.23 μg kg
−1
, while the other targeted molecules were not detected. The proposed methodology then appeared suitable for the further monitoring of a potential decrease of BPA levels and an increase of other BPA analogue levels as reflective of the expected incoming trend in terms of human exposure.
Graphical abstract
Analytical strategy for the determination of bisphenol compounds in human breast milk samples
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In developed countries, where omphalitis has become rare and related mortality nil, benefits of antiseptic use in umbilical cord care have not been demonstrated. We aimed to assess the noninferiority ...of dry care compared with antiseptics in France where antiseptic use is widespread.
We conducted a noninferiority, cluster-randomized, 2-period crossover trial, in 6 French university maternity units including all infants born after 36 weeks' gestation. Maternity units were randomly assigned to provide either their usual antiseptic care or a dry care umbilical cord method for a 4-month period, and then units switched to the alternate cord cleansing method for a 4-month period. The primary outcome was neonatal omphalitis, adjudicated by an independent blinded committee based on all available photographs, clinical, and bacteriological data. We used a noninferiority margin of 0.4%. Analysis was performed per protocol and by intention to treat.
Among 8698 participants, omphalitis occurred in 3 of 4293 (0.07%) newborns in the dry care group and in none of the 4404 newborns in the antiseptic care group (crude difference: 0.07; 95% confidence interval: -0.03 to 0.21). Late neonatal infection, parental appreciation of difficulty in care, and time to separation of the cord were not significantly different between the 2 groups.
Dry cord was noninferior to the use of antiseptics in preventing omphalitis in full-term newborns in a developed country. Antiseptic use in umbilical cord care is therefore unnecessary, constraining, and expensive in high-income countries and may be replaced by dry care.
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