The Impact of the PI3K/Akt Signaling Pathway in Anxiety and Working Memory in Young and Middle-Aged PDK1 K465E Knock-In Mice

Dysfunction and dysregulation at the genetic, neural, and behavioral levels point at the fine-tuning of broadly spread networks as critical for a wide array of behaviors and mental processes through the life span. This brain-based evidence, from basic to behavioral neuroscience levels, is leading to a new conceptualization of mental health and disease. Thus, the Research Domain Criteria considers phenotypic differences observed among disorders as explained by variations in the nature and degree of neural circuitry disruptions, under the modulation of several developmental, compensatory, environmental, and epigenetic factors. In this context, we aimed to describe for the first time the in vivo behavioral impact of tweaking the PI3K/Akt signaling pathway known to play an essential role in the regulation of cellular processes, leading to diverse physiological responses. We explored the effects in young (YA, 3-4 months of age) and mature (MA, 11-14 months of age) male and female PDK1 K465E knock-in mice in a battery of tests under different anxiogenic conditions. The results evidenced that the double mutation of the PDK1 pleckstrin homology (PH) domain resulted in an enhancement of the negative valence system shown as an increase of responses of fear- and anxiety-like behaviors in anxiogenic situations. Interestingly, this seemed to be specific of YA and found regulated at middle age. In contrast, cognitive deficits, as measured in a spatial working memory task, were found in both YA and MA mutants and independently of the level of their anxious-like profiles. These distinct age- and function-dependent impacts would be in agreement with the distinct cortical and limbic deficits in the Akt signaling in the brain we have recently described in these same animals. The elicitation of age- and neuronal-dependent specific patterns suggests that fine-tuning the intensity of the PKB/Akt signal that enables diverse physiological response has also its in vivo translation into the negative valence system and age is a key regulatory factor

Sex-dependent signatures, time frames and longitudinal fine-tuning of the marble burying test in normal and ad-pathological aging mice

Altres ajuts: This work was funded by UAB-GE-260408 to L.G.-L.It also received financial support from Memorial Mercedes Llort Sender 2021/80/09241941.6.The marble burying (MB) test, a classical test based on the natural tendency of rodents to dig in diverse substrates and to bury small objects, is sensitive to some intrinsic and extrinsic factors. Here, under emerging neuroethological quantitative and qualitative analysis, the MB performance of 12-month-old male and female 3xTg-AD mice for Alzheimer's disease and age-matched counterparts of gold-standard C57BL6 strain with normal aging unveiled sex-dependent signatures. In addition, three temporal analyses, through the (1) time course of the performance, and (2) a repeated test schedule, identified the optimal time frames and schedules to detect sex-and genotype-dependent differences. Besides, a (3) longitudinal design from 12 to 16 months of age monitored the changes in the performance with aging, worsening in AD-mice, and modulation through the repeated test. In summary, the present results allow us to conclude that (1) the marble burying test is responsive to genotype, sex, aging, and its interactions; (2) the male sex was more sensitive to showing the AD-phenotype; (3) longitudinal assessment shows a reduction in females with AD pathology; (4) burying remains stable in repeated testing; (5) the time-course of marbles burying is useful; and (6) burying behavior most likely represents perseverative and/or stereotyped-like behavior rather than anxiety-like behavior in 3xTg-AD mice

Nova descoberta sobre la formació de neurones

Investigadors del Institut de Neurociències i del Departament de Bioquímica i Biologia Molecular de la UAB han definit una via de senyalització intracel·lular clau per a la correcta formació de les neurones. La recerca, liderada pel doctor Jose R. Bayascas, ha estat publicada a Molecular and Cellular Biology, i pot permetre en el futur desenvolupar fàrmacs d'interès terapèutic, especialment en el camp de la psiquiatria.Investigadores del Instituto de Neurociencias y del Departamento de Bioquímica y Biología Molecular de la UAB han definido una vía de señalización intracelular clave para la correcta formación de las neuronas. La investigación, liderada por el doctor Jose R. Bayascas, ha sido publicada en Molecular and Cellular Biology y puede permitir desarrollar fármacos de interés terapéutico en el futuro, especialmente en el campo de la psiquiatría

Molecular Insights into the Regulation of 3-Phosphoinositide-Dependent Protein Kinase 1 : Modeling the Interaction between the Kinase and the Pleckstrin Homology Domains

The 3-phosphoinositide-dependent protein kinase 1 (PDK1) K465E mutant kinase can still activate protein kinase B (PKB) at the membrane in a phosphatidylinositol-3,4,5-trisphosphate (PIP3, PtdIns(3,4,5)P3) independent manner. To understand this new PDK1 regulatory mechanism, docking and molecular dynamics calculations were performed for the first time to simulate the wild-type kinase domain-pleckstrin homology (PH) domain complex with PH-in and PH-out conformations. These simulations were then compared to the PH-in model of the KD-PH(mutant K465E) PDK1 complex. Additionally, three KD-PH complexes were simulated, including a substrate analogue bound to a hydrophobic pocket (denominated the PIF-pocket) substrate-docking site. We find that only the PH-out conformation, with the PH domain well-oriented to interact with the cellular membrane, is active for wild-type PDK1. In contrast, the active conformation of the PDK1 K465E mutant is PH-in, being ATP-stable at the active site while the PIF-pocket is more accessible to the peptide substrate. We corroborate that both the docking-site binding and the catalytic activity are in fact enhanced in knock-in mouse samples expressing the PDK1 K465E protein, enabling the phosphorylation of PKB in the absence of PIP3binding

Acox2 is a regulator of lysine crotonylation that mediates hepatic metabolic homeostasis in mice

Acyl-CoA oxidase 2 (Acox2) is an enzyme involved in peroxisomal bile acid synthesis and branched-chain fatty acid degradation. Acox2 knockout (−/−) mice spontaneously developed liver cancer with marked lymphocytic infiltrate. Tandem-affinity purification coupled with mass spectrometry analysis revealed that Acox2 interacted with methylcrotonoyl-CoA carboxylase followed by co-immunoprecipitation confirmation. Here we reported that non-histone lysine crotonylation (Kcr) levels were downregulated in Acox2 −/− mice livers. Interestingly, Kcr signals were concentrated in the nucleus of tumor cells but mostly located in the cytoplasm of adjacent normal liver cells of Acox2 −/− mice. Quantitative analysis of the global crotonylome further revealed that 54% (27/50) of downregulated non-histone Kcr sites were located in mitochondrial (11/50) and peroxisomal (17/50) enzymes including Ehhadh, Scp2, Hsd17b4, Crot, Etfa, Cpt1a, Eci1/2, Hadha, Etfdh, and Idh2. Subsequent site-directed mutagenesis and transcriptome analysis revealed that Ehhadh K 572 cr might have site-specific regulatory roles by downregulating TOP3B expression that lead to increased DNA damage in vitro. Our findings suggested Acox2 is a regulator of Kcr that might play critical role on hepatic metabolic homeostasis

Mutation of the 3-phosphoinositide-dependent protein kinase-1 (PDK1) substrate-docking site in the developing brain causes microcephaly with abnormal brain morphogenesis independently of Akt, leading to impaired cognition and disruptive behaviors

The phosphoinositide 3-kinase (PI 3-kinase)/Akt signaling pathway plays essential roles during neuronal development. The 3-phosphoinositide-dependent protein kinase 1 (PDK1) coordinates the PI 3-kinase signals by activating twenty three kinases of the AGC family including Akt. Phosphorylation of a conserved docking site in the substrate is a requisite for PDK1 to recognize, phosphorylate and activate most of these kinases, with the exception of Akt. We exploited this differential mechanism of regulation by generating neuronal-specific conditional knock-in mice expressing the mutant form of PDK1 L155E in which the substrate-docking site binding motif, termed the PIF-pocket, was disrupted. As a consequence, activation of all the PDK1 substrates tested excluding Akt was abolished. Mice exhibited microcephaly, altered cortical layering and reduced circuitry, leading to cognitive deficits and exacerbated disruptive behavior combined with diminished motivation. The abnormal patterning of the adult brain arise from the reduced ability of the embryonic neurons to polarize and extend their axons, therefore highlighting the essential roles that the PDK1 signaling beyond Akt plays in mediating the neuronal responses that are instructive for brain development

The ERK5/NF-κB signaling pathway targets endometrial cancer proliferation and survival

Endometrial cancer (EC) is the most common type of gynecologic cancer in women of developed countries. Despite surgery combined with chemo-/radiotherapy regimens, overall survival of patients with high-risk EC tumors is poor, indicating a need for novel therapies. The MEK5-ERK5 pathway is activated in response to growth factors and to different stressors, including oxidative stress and cytokines. Previous evidence supports a role for the MEK5-ERK5 pathway in the pathology of several cancers. We investigated the role of ERK5 in EC. In silico analysis of the PanCancer Atlas dataset showed altera- tions in components of the MEK5-ERK5 pathway in 48% of EC patients. Here, we show that ERK5 inhibition or silencing decreased EGF-induced EC cell proliferation, and that genetic deletion of MEK5 resulted in EC impaired proliferation and reduced tumor growth capacity in nude mice. Pharmacologic inhibition or ERK5 silencing impaired NF-kB pathway in EC cells and xenografts. Furthermore, we found a positive correlation between ERK5 and p65/RELA protein levels in human EC tumor samples. Mechanistically, genetic or pharmacologic impairment of ERK5 resulted in downregulation of NEMO/ IKKγ expression, leading to impaired p65/RELA activity and to apoptosis in EC cells and xenografts, which was rescued by NEMO/IKKγ overexpression. Notably, ERK5 inhibition, MEK5 deletion or NF-kB inhibition sensitized EC cells to standard EC chemotherapy (paclitaxel/carboplatin) toxicity, whereas ERK5 inhibition synergized with paclitaxel to reduce tumor xenograft growth in mice. Together, our results suggest that the ERK5-NEMO-NF-κB pathway mediates EC cell prolifera- tion and survival. We propose the ERK5/NF-κB axis as new target for EC treatment.The online version contains supplementary material available at 10.1007/s00018-022-04541-

MicroRNA-497 impairs the growth of chemoresistant neuroblastoma cells by targeting cell cycle, survival and vascular permeability genes

Despite multimodal therapies, a high percentage of high-risk neuroblastoma (NB) become refractory to current treatments, most of which interfere with cell cycle and DNA synthesis or function, activating the DNA damage response (DDR). In cancer, this process is frequently altered by deregulated expression or function of several genes which contribute to multidrug resistance (MDR). MicroRNAs are outstanding candidates for therapy since a single microRNA can modulate the expression of multiple genes of the same or different pathways, thus hindering the development of resistance mechanisms by the tumor. We found several genes implicated in the MDR to be overexpressed in high-risk NB which could be targeted by microRNAs simultaneously. Our functional screening identified several of those microRNAs that reduced proliferation of chemoresistant NB cell lines, the best of which was miR-497. Low expression of miR-497 correlated with poor patient outcome. The overexpression of miR-497 reduced the proliferation of multiple chemoresistant NB cell lines and induced apoptosis in MYCN-amplified cell lines. Moreover, the conditional expression of miR-497 in NB xenografts reduced tumor growth and inhibited vascular permeabilization. MiR-497 targets multiple genes related to the DDR, cell cycle, survival and angiogenesis, which renders this molecule a promising candidate for NB therapy

The long form of fas apoptotic inhibitory molecule is expressed specifically in neurons and protects them against death receptor-triggered apoptosis

Death receptors (DRs) and their ligands are expressed in developing nervous system. However, neurons are generally resistant to death induction through DRs and rather their activation promotes neuronal outgrowth and branching. These results suppose the existence of DRs antagonists expressed in the nervous system. Fas apoptosis inhibitory molecule (FAIMS ) was first identified as a Fas antagonist in B-cells. Soon after, a longer alternative spliced isoform with unknown function was identified and named FAIML. FAIMS is widely expressed, including the nervous system, and we have shown previously that it promotes neuronal differentiation but it is not an anti-apoptotic molecule in this system. Here, we demonstrate that FAIML is expressed specifically in neurons, and its expression is regulated during the development. Expression could be induced by NGF through the extracellular regulated kinase pathway in PC12(pheochromocytoma cell line) cells. Contrary to FAIMS , FAIML does not increase the neurite outgrowth induced by neurotrophins and does not interfere with nuclear factor ĸB pathway activation as FAIMS does. Cells overexpressing FAIML are resistant to apoptotic cell death induced by DRs such as Fas or tumor necrosis factor R1. Reduction of endogenous expression by small interfering RNA shows that endogenousFAIML protects primary neurons from DR-induced cell death. The detailed analysis of this antagonism shows thatFAIML can bind to Fas receptor and prevent the activation of the initiator caspase-8 induced by Fas. In conclusion, our results indicate that FAIML could be responsible for maintaining initiator caspases inactive after receptor engagement protecting neurons from the cytotoxic action of death ligands