Plant-Origin Components: New Players to Combat Antibiotic Resistance in Klebsiella pneumoniae.

Klebsiella pneumoniae (Kpn) is an opportunistic pathogen that causes intrahospital complications such as pneumonia, liver abscesses, soft tissue infections, urinary infections, bacteraemia, and, in some cases, death. Since this bacterium has a higher frequency than other Gram-negative pathogens, it has become an important pathogen to the health sector. The adaptative genome of Kpn likely facilitates increased survival of the pathogen in diverse situations. Therefore, several studies have been focused on developing new molecules, synergistic formulations, and biomaterials that make it possible to combat and control infections with and dispersion of this pathogen. Note that the uncontrolled antibiotic administration that occurred during the pandemic led to the emergence of new multidrug-resistant strains, and scientists were challenged to overcome them. This review aims to compile the latest information on Kpn that generates intrahospital infections, specifically their pathogenicity-associated factors. Furthermore, it explains the natural-product-based treatments (extracts and essential oils) developed for Kpn infection and dispersion control.

Transcriptome-Wide Analysis of Low-Concentration Exposure to Bisphenol A, S, and F in Prostate Cancer Cells.

Bisphenol A (BPA) is a ubiquitous synthetic compound used as a monomer in the production of polycarbonate plastics and epoxy resins. Even at low doses, BPA has been associated with the molecular progression of diseases such as obesity, metabolic syndrome, and hormone-regulated cancers due to its activity as an endocrine-disrupting chemical (EDC). Consequently, the use of BPA has been regulated worldwide by different health agencies. BPA structural analogs such as bisphenol S and bisphenol F (BPS and BPF) have emerged as industrial alternatives, but their biological activity in the molecular progression of cancer remains unclear. Prostate cancer (PCa) is a hormone-dependent cancer, and the role of BPA structural analogs in PCa progression is still undescribed. In this work, we use an in vitro model to characterize the transcriptomic effect of low-concentration exposure to bisphenol A, S, or F in the two main stages of the disease: androgen dependency (LNCaP) and resistance (PC-3). Our findings demonstrated that the low concentration exposure to each bisphenol induced a differential effect over PCa cell lines, which marks the relevance of studying the effect of EDC compounds through all the stages of the disease.

Differential expression of Dp71 and Dp40 isoforms in proliferating and differentiated neural stem cells: Identification of Dp40 splicing variants.

Dp71 and Dp40 are the main products of the DMD gene in the central nervous system, and they are developmentally regulated from the early stages of embryonic development to adulthood. To further study the roles of Dp71 and Dp40 during cell proliferation and neural differentiation, we analyzed Dp71/Dp40 isoform expression at the mRNA level by RT-PCR assays to identify alternative splicing (AS) in the isoforms expressed in rat neural stem/progenitor cells (NSPCs) and in differentiated cells (neurons and glia). We found that proliferating NSPCs expressed Dp71d, Dp71dΔ71, Dp71f, Dp71fΔ71, Dp71dΔ74 and Dp40, as well as two Dp40 isoforms: Dp40Δ63,64 and Dp40Δ64-67. In differentiated cells we also found the expression of Dp71d, Dp71dΔ71, Dp71f, Dp71fΔ71 and Dp40. However, the expression frequencies were different in both stages. In addition, in differentiated cells, we found Dp71fΔ71-74, and interestingly, we did not find the expression of Dp71dΔ74 or the newly identified Dp40 isoforms. In this work we show that NSPC differentiation is accompanied by changes in Dp71/Dp40 isoform expression, suggesting different roles for these isoforms in NSPCs proliferation and neuronal differentiation, and we describe, for the first time, alternative splicing of Dp40.

Negative feedback-loop mechanisms regulating HOG- and pheromone-MAPK signaling in yeast.

The pheromone response and the high osmolarity glycerol (HOG) pathways are considered the prototypical MAPK signaling systems. They are the best-understood pathways in eukaryotic cells, yet they continue to provide insights in how cells relate with the environment. These systems are subjected to tight regulatory circuits to prevent hyperactivation in length and intensity. Failure to do this may be a matter of life or death specially for unicellular organisms such as Saccharomyces cerevisiae. The signaling pathways are fine-tuned by positive and negative feedback loops exerted by pivotal control elements that allow precise responses to specific stimuli, despite the fact that some elements of the systems are common to different signaling pathways. Here we describe the experimentally proven negative feedback loops that modulate the pheromone response and the HOG pathways. As described in this review, MAP kinases are central mechanistic components of these feedback loops. They have the capacity to modulate basal signaling activity, a fast extranuclear response, and a longer-lasting transcriptional process.

Wnt/ß-Catenin/TCF Pathway Is a Phase-Dependent Promoter of Colony Formation and Mesendodermal Differentiation During Human Somatic Cell Reprogramming.

Somatic cell reprogramming is a biphasic phenomenon that goes through a mesenchymal-to-epithelial transition, called initiation phase, followed by a maturation phase wherein reprogramming cells acquire pluripotency. Here, we show that these phases display a differential response to Wnt signaling activation. Wnt signaling increases colony formation by promoting cellular epithelialization during the initiation phase in a TCF7-dependent manner. However, during maturation phase, it is also responsible for inducing mesendodermal differentiation, which is negatively regulated by TCF7L1. Thus, Wnt signaling inhibition or TCF7L1 overexpression downregulates mesendodermal gene expression without perturbing pluripotency. Together, our results demonstrate that a phase-specific modulation of Wnt signaling leads to an improved reprogramming efficiency in terms of colony output and pluripotency acquisition. This work provides new insights into the cell context-dependent roles of Wnt signaling during human somatic cell reprogramming. Stem Cells 2018;36:683-695.

Dp71Δ78-79 dystrophin mutant stimulates neurite outgrowth in PC12 cells via upregulation and phosphorylation of HspB1.

PC12 cells acquire a neuronal phenotype in response to nerve growth factor (NGF). However, this phenotype is more efficiently achieved when the Dp71Δ78-79 dystrophin mutant is stably expressed in PC12-C11 cells. To investigate the effect of Dp71Δ78-79 overexpression on the protein profile of PC12-C11 cells, we compared the expression profiles of undifferentiated and NGF-differentiated PC12-C11 and PC12 cells by 2DE. In undifferentiated cultures, one protein was downregulated, and five were upregulated. Dp71Δ78-79 overexpression had a greater effect on differentiated cultures, with ten proteins downregulated and seven upregulated. The protein with the highest upregulation was HspB1. Changes in HspB1 expression were validated by Western blot and immunofluorescence analyses. Interestingly, the neurite outgrowth in PC12-C11 cells was affected by a polyclonal antibody against HspB1, and the level of HspB1 and HspB1Ser86 decreased, suggesting an important role for this protein in this cellular process. Our results show that Dp71Δ78-79 affects the expression level of some proteins and that the stimulated neurite outgrowth produced by this mutant is mainly through upregulation and phosphorylation of HspB1.

Antiproliferative and Antimigratory Activity of Poly-gallic Acid in Cancer Cell Lines.

BACKGROUND/AIM: Enzyme-mediated grafting of poly (gallic acid) (PGAL) and L-arginine and a-L-lysine onto PGAL produces reactive oxygen species (ROS)-suppressor multiradical molecules with low cytotoxicity, high thermostability and water solubility with cancer treatment potential. This study examined the anticancer effects of these molecules in hepatic (HepG2, ATCC HB-8065), breast (MCF7, ATCC HTB-22), and prostate (PC-3, ATCC CRL-1435 and DU 145, ATCC HTB-81) cancer cell lines, as well as in fibroblasts from healthy human skin as control cells. MATERIALS AND METHODS: PGAL was synthesized by the oxidative polymerization of the naturally abundant GA using laccase from Trametes versicolor. Insertions of amino acids L-arginine and α-L-lysine on the PGAL chain were carried out by microwave. The cells of dermal fibroblast (Fb) were obtained from primary skin cultures and isolated from skin biopsies. The cancer cells lines of hepatic (HepG2), breast (MCF7), and prostate (PC-3, DU 145) were obtained from ATCC. The viability of the cancer cells and the primary culture was obtained by the MTT assay. Proliferation was demonstrated by crystal violet assay. Cell migration was determined by Wound healing assay. Finally, cell cycle analysis was carried out with cells. RESULTS: The results show that 200 µg/ml of PGAL cultured in vitro with prostate cancer cells decreased viability, proliferation, and migration, as well as arrested cells in the G1 and S phases of the cell cycle. In contrast, the dermal fibroblasts and the hepatic line remained unaffected. The random grafting of L-Arg and a-L-Lys onto the PGAL chain also decreased the viability of prostate cancer cells. CONCLUSION: PGAL and PGAL-grafted amino acids are potential adjuvants for prostate cancer treatment, with improved physicochemical characteristics compared to GA.

Expression of Dystrophin Dp71 Splice Variants Is Temporally Regulated During Rodent Brain Development.

Dystrophin Dp71 is the major product of the Duchenne muscular dystrophy (DMD) gene in the brain, and its loss in DMD patients and mouse models leads to cognitive impairments. Dp71 is expressed as a range of proteins generated by alternative splicing of exons 71 to 74 and 78, classified in the main Dp71d and Dp71f groups that contain specific C-terminal ends. However, it is unknown whether each isoform has a specific role in distinct cell types, brain regions, and/or stages of brain development. In the present study, we characterized the expression of Dp71 isoforms during fetal (E10.5, E15.5) and postnatal (P1, P7, P14, P21 and P60) mouse and rat brain development. We finely quantified the expression of several Dp71 transcripts by RT-PCR and cloning assays in samples from whole-brain and distinct brain structures. The following Dp71 transcripts were detected: Dp71d, Dp71d∆71, Dp71d∆74, Dp71d∆71,74, Dp71d∆71-74, Dp71f, Dp71f∆71, Dp71f∆74, Dp71f∆71,74, and Dp71fΔ71-74. We found that the Dp71f isoform is the main transcript expressed at E10.5 (> 80%), while its expression is then progressively reduced and replaced by the expression of isoforms of the Dp71d group from E15.5 to postnatal and adult ages. This major finding was confirmed by third-generation nanopore sequencing. In addition, we found that the level of expression of specific Dp71 isoforms varies as a function of postnatal stages and brain structure. Our results suggest that Dp71 isoforms have different and complementary roles during embryonic and postnatal brain development, likely taking part in a variety of maturation processes in distinct cell types.

Estimation of the relative biological effectiveness (RBE) of the Lu-DOTA-iPSMA177 radiopharmaceutical.

Relative biological effectiveness is a radiobiological parameter relevant in radiotherapy planning and useful in evaluating the physiological impact of radiation in different tissues. Targeted radionuclide therapy allows the selective and specific deposition of higher radiation doses in a noninvasive way and without collateral effects through the administration of radiopharmaceuticals. Lu-DOTA-177(hydrazinylnicotinoyl-Lys-(Nal)-NH-CO-NH-Glu) also called Lu-iPSMA177 is a third generation radiopharmaceutical composed by a peptide that recognizes the prostate-specific membrane antigen (PSMA), a membrane protein overexpressed in several types of cancer and that mediates the radiopharmaceutical's recognition of cancer cells. The present study reports radiobiological parameters of Lu-iPSMA177 and demonstrates the superiority of targeted radiopharmaceuticals over external radiotherapy treatment options in terms of their relative biological effectiveness. The relative biological effectiveness value of 1.020±0.003 for the LINAC, estimated by fitting the linear-quadratic model equation to the resulting survival curves, was like those of 1.25±0.04,1.060±0.005and1.00±0.04 obtained by an alternative method in relation to the mean lethal doses at 90, 80 or 60 survival percent respectively. While the relative biological effectiveness values of 5.65±0.13,4.72±0.27and2.87±0.19 estimated for Lu-iPSMA177 were significantly higher than those for the LINAC. The results confirm that the biological effect produced by the deposition of a radiation absorbed dose delivered by the LINAC can be induced with a quarter of that dose using Lu-iPSMA177 due to the energy distribution, dose-rate and energy fluence.

SFRP1 induces a stem cell phenotype in prostate cancer cells.

Prostate cancer (PCa) ranks second in incidence and sixth in deaths globally. The treatment of patients with castration-resistant prostate cancer (CRPC) continues to be a significant clinical problem. Emerging evidence suggests that prostate cancer progression toward castration resistance is associated with paracrine signals from the stroma. SFRP1 is one of the extracellular proteins that modulate the WNT pathway, and it has been identified as a mediator of stromal epithelium communication. The WNT pathway is involved in processes such as cell proliferation, differentiation, cell anchoring, apoptosis, and cell cycle regulation as well as the regulation of stem cell populations in the prostatic epithelium. In the present study, we explored the role of exogenous SFRP1 on the stem cell phenotype in prostate cancer. The results reveal that cancer stem cell markers are significantly increased by exogenous SFRP1 treatments, as well as the downstream target genes of the Wnt/-catenin pathway. The pluripotent transcription factors SOX2, NANOG, and OCT4 were also up-regulated. Furthermore, SFRP1 promoted prostate cancer stem cell (PCSC) properties in vitro, including tumorsphere formation, migration, bicalutamide resistance, and decreased apoptosis. Taken together, our results indicate that SFRP1 participates in the paracrine signaling of epithelial cells, influencing them and positively regulating the stem cell phenotype through deregulation of the WNT/ß-catenin pathway, which could contribute to disease progression and therapeutic failure. This research increases our molecular understanding of how CRPC progresses, which could help us find new ways to diagnose and treat the disease.

Unraveling the Role of EV-Derived miR-150-5p in Prostate Cancer Metastasis and Its Association with High-Grade Gleason Scores: Implications for Diagnosis.

Metastasis remains the leading cause of mortality in prostate cancer patients. The presence of tumor cells in lymph nodes is an established prognostic indicator for several cancer types, such as melanoma, breast, oral, pancreatic, and cervical cancers. Emerging evidence highlights the role of microRNAs enclosed within extracellular vesicles as facilitators of molecular communication between tumors and metastatic sites in the lymph nodes. This study aims to investigate the potential diagnostic utility of EV-derived microRNAs in liquid biopsies for prostate cancer. By employing microarrays on paraffin-embedded samples, we characterized the microRNA expression profiles in metastatic lymph nodes, non-metastatic lymph nodes, and primary tumor tissues of prostate cancer. Differential expression of microRNAs was observed in metastatic lymph nodes compared to prostate tumors and non-metastatic lymph node tissues. Three microRNAs (miR-140-3p, miR-150-5p, and miR-23b-3p) were identified as differentially expressed between tissue and plasma samples. Furthermore, we evaluated the expression of these microRNAs in exosomes derived from prostate cancer cells and plasma samples. Intriguingly, high Gleason score samples exhibited the lowest expression of miR-150-5p compared to control samples. Pathway analysis suggested a potential regulatory role for miR-150-5p in the Wnt pathway and bone metastasis. Our findings suggest EV-derived miR-150-5p as a promising diagnostic marker for identifying patients with high-grade Gleason scores and detecting metastasis at an early stage.

Aptamers as Theragnostic Tools in Prostate Cancer.

Despite of the capacity that several drugs have for specific inhibition of the androgen receptor (AR), in most cases, PCa progresses to an androgen-independent stage. In this context, the development of new targeted therapies for prostate cancer (PCa) has remained as a challenge. To overcome this issue, new tools, based on nucleic acids technology, have been developed. Aptamers are small oligonucleotides with a three-dimensional structure capable of interacting with practically any desired target, even large targets such as mammalian cells or viruses. Recently, aptamers have been studied for treatment and detection of many diseases including cancer. In PCa, numerous works have reported their use in the development of new approaches in diagnostics and treatment strategies. Aptamers have been joined with drugs or other specific molecules such as silencing RNAs (aptamer-siRNA chimeras) to specifically reduce the expression of oncogenes in PCa cells. Even though these studies have shown good results in the early stages, more research is still needed to demonstrate the clinical value of aptamers in PCa. The aim of this review was to compile the existing scientific literature regarding the use of aptamers in PCa in both diagnosis and treatment studies. Since Prostate-Specific Membrane Antigen (PSMA) aptamers are the most studied type of aptamers in this field, special emphasis was given to these aptamers.

Clinical features and severe acute respiratory syndrome-coronavirus-2 structural protein-based serology of Mexican children and adolescents with coronavirus disease 2019.

Severe acute respiratory syndrome (SARS)-coronavirus (CoV)-2 infection in children and adolescents primarily causes mild or asymptomatic coronavirus disease 2019 (COVID-19), and severe illness is mainly associated with comorbidities. However, the worldwide prevalence of COVID-19 in this population is only 1%-2%. In Mexico, the prevalence of COVID-19 in children has increased to 10%. As serology-based studies are scarce, we analyzed the clinical features and serological response (SARS-CoV-2 structural proteins) of children and adolescents who visited the Hospital Infantil de México Federico Gómez (October 2020-March 2021). The majority were 9-year-old children without comorbidities who were treated as outpatients and had mild-to-moderate illness. Children aged 6-10 years and adolescents aged 11-15 years had the maximum number of symptoms, including those with obesity. Nevertheless, children with comorbidities such as immunosuppression, leukemia, and obesity exhibited the lowest antibody response, whereas those aged 1-5 years with heart disease had the highest levels of antibodies. The SARS-CoV-2 spike receptor-binding domain-localized peptides and M and E proteins had the best antibody response. In conclusion, Mexican children and adolescents with COVID-19 represent a heterogeneous population, and comorbidities play an important role in the antibody response against SARS-CoV-2 infection.

Embryonic neural stem/progenitor cells as model to characterize dystrophin and dystrophin-associated proteins expression during neuronal or astrocytic differentiation.

Neural stem/progenitor cells (NSPC) are multipotent cells that renew themselves and could differentiate into neurons and macro glia (astrocytes and oligodendrocytes) of the nervous system during embryonic development. Duchenne muscular dystrophy is a severe type of muscular dystrophy caused by mutations in the dmd gene, and one-third of patients cursed with neuro-cognitive impairments. In this data article, we take advantage of the differentiation capacity of NSPC as a model to increase our knowledge in the neuronal and/or astrocytic differentiation and to evaluate the expression of dystrophins and dystrophin-associated proteins. We showed the characterization of undifferentiated and neuron and/or astrocyte differentiated NSPC. In addition, we evaluated the expression and subcellular localization of dystrophins and ß-dystroglycan in undifferentiated NSPC and differentiated to neurons and astrocytes.•Primary culture of NSPC was characterized by the expression of multipotent markers nestin and Sox2.•Neuronal or astrocytic differentiation of NSPC was performed by basic fibroblast growth factor (FGF2) withdrawal, histamine or ciliary neurotrophic factor (CNTF) treatment, and expression of ßIII-tubulin or glial fibrillary acidic protein (GFAP) as differentiation markers for neurons or astrocytes was evaluated.•This study will contribute to the understanding of dystrophins and dystrophin-associated proteins expression and function during neuronal or astrocytic differentiation of NSPC.

Pseudotyped Vesicular Stomatitis Virus-Severe Acute Respiratory Syndrome-Coronavirus-2 Spike for the Study of Variants, Vaccines, and Therapeutics Against Coronavirus Disease 2019.

World Health Organization (WHO) has prioritized the infectious emerging diseases such as Coronavirus Disease (COVID-19) in terms of research and development of effective tests, vaccines, antivirals, and other treatments. Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2), the etiological causative agent of COVID-19, is a virus belonging to risk group 3 that requires Biosafety Level (BSL)-3 laboratories and the corresponding facilities for handling. An alternative to these BSL-3/-4 laboratories is to use a pseudotyped virus that can be handled in a BSL-2 laboratory for study purposes. Recombinant Vesicular Stomatitis Virus (VSV) can be generated with complementary DNA from complete negative-stranded genomic RNA, with deleted G glycoprotein and, instead, incorporation of other fusion protein, like SARS-CoV-2 Spike (S protein). Accordingly, it is called pseudotyped VSV-SARS-CoV-2 S. In this review, we have described the generation of pseudotyped VSV with a focus on the optimization and application of pseudotyped VSV-SARS-CoV-2 S. The application of this pseudovirus has been addressed by its use in neutralizing antibody assays in order to evaluate a new vaccine, emergent SARS-CoV-2 variants (delta and omicron), and approved vaccine efficacy against variants of concern as well as in viral fusion-focused treatment analysis that can be performed under BSL-2 conditions.

Characterization of the expression of dystrophins and dystrophin-associated proteins during embryonic neural stem/progenitor cell differentiation.

Duchenne muscular dystrophy (DMD) is a genetic disease caused by mutations in the dystrophin gene. Dystrophin is required for the organization of a complex consisting of dystroglycans, sarcoglycans, dystrobrevins and syntrophins, known as the dystrophin-associated proteins complex (DAPC). In addition to muscle degeneration, cognitive impairment has been reported in DMD patients. To characterize a suitable model for studying the embryonic cerebral functions of dystrophin, we analyzed the expression patterns of dystrophins/DAPC in undifferentiated and differentiated embryonic neural stem/progenitor cells (NSPC). We found that NSPC express mRNAs for dystrophins Dp427, Dp140, Dp71 and Dp40; ß-dystroglycan; α- and ß-dystrobrevin; α1-, ß1-, ß2- and γ2-syntrophin; and ß-, γ-, δ- and ε-sarcoglycan. Some of these were differentially regulated during neuronal or astrocytic differentiation. Interestingly, the protein expression levels of Dp140, ß-dystroglycan and α2-dystrobrevin were also differentially regulated. Additionally, we found that proliferating NSPC and differentiated neurons and astrocytes show immuno-positive staining for dystrophins and ß-dystroglycan. Our results show that dystrophins and DAPC components are expressed and regulated during the neuronal or astrocytic differentiation of NSPC, suggesting that these proteins may have different roles in the brain development.

Histamine up-regulates fibroblast growth factor receptor 1 and increases FOXP2 neurons in cultured neural precursors by histamine type 1 receptor activation: conceivable role of histamine in neurogenesis during cortical development in vivo.

BACKGROUND: During rat development, histamine (HA) is one of the first neuroactive molecules to appear in the brain, reaching its maximal value at embryonic day 14, a period when neurogenesis of deep layers is occurring in the cerebral cortex, suggesting a role of this amine in neuronal specification. We previously reported, using high-density cerebrocortical neural precursor cultures, that micromolar HA enhanced the effect of fibroblast growth factor (FGF)-2 on proliferation, and that HA increased neuronal differentiation, due to HA type 1 receptor (H(1)R) activation. RESULTS: Clonal experiments performed here showed that HA decreased colony size and caused a significant increase in the percentage of clones containing mature neurons through H(1)R stimulation. In proliferating precursors, we studied whether HA activates G protein-coupled receptors linked to intracellular calcium increases. Neural cells presented an increase in cytoplasmic calcium even in the absence of extracellular calcium, a response mediated by H(1)R. Since FGF receptors (FGFRs) are known to be key players in cell proliferation and differentiation, we determined whether HA modifies the expression of FGFRs1-4 by using RT-PCR. An important transcriptional increase in FGFR1 was elicited after H(1)R activation. We also tested whether HA promotes differentiation specifically to neurons with molecular markers of different cortical layers by immunocytochemistry. HA caused significant increases in cells expressing the deep layer neuronal marker FOXP2; this induction of FOXP2-positive neurons elicited by HA was blocked by the H(1)R antagonist chlorpheniramine in vitro. Finally, we found a notable decrease in FOXP2+ cortical neurons in vivo, when chlorpheniramine was infused in the cerebral ventricles through intrauterine injection. CONCLUSION: These results show that HA, by activating H(1)R, has a neurogenic effect in clonal conditions and suggest that intracellular calcium elevation and transcriptional up-regulation of FGFR1 participate in HA-induced neuronal differentiation to FOXP2 cells in vitro; furthermore, H(1)R blockade in vivo resulted in decreased cortical FOXP2+ neurons.

Activin and TGF-ß effects on brain development and neural stem cells.

Transforming Growth Factor-ß (TGF-ß) family members are ubiquitously expressed, participating in the regulation of many processes in different cell types both in embryonic and adult stages. Several members of this family, including Activins, TGF-ß1-3 and Nodal, have been implicated in the development and maintenance of various organs, in which stem cells play important roles. Although TGF-ß was initially considered an injury-related cytokine, it became clear that not only TGF-ß, but other members of this family, play critical roles in morphogenesis and cell lineage specification. During brain development, Activin and TGF-ßs as well as their cognate receptors, are expressed in different patterns. The roles of Activin and TGF-ß during CNS development are sometimes contradictory, because these proteins present different actions depending on the cell type and the context. The aim of this review is to summarize current information on the actions of TGF-ß members during developing brain, and also on Neural Stem/Progenitor Cells (NSPC). We focus on the TGF-ß subgroup, specifically on the effects of TGF-ß1 and Activin A. In the first section we describe the main characteristics of the ligands, its receptors as well as the proteins and mechanisms involved in signaling. Next, we discuss the main advances concerning TGF-ß1 and Activin actions during brain development and their roles in NSPC fate decision and neuroprotection both in vitro and in vivo. The emerging picture from these studies suggests that these growth factors can be used to manipulate neurogenesis and might help to achieve restoration after brain deterioration.

Activin A promotes neuronal differentiation of cerebrocortical neural progenitor cells.

BACKGROUND: Activin A is a protein that participates principally in reproductive functions. In the adult brain, Activin is neuroprotective, but its role in brain development is still elusive. METHODOLOGY/PRINCIPAL FINDINGS: We studied if Activin A influences proliferation, differentiation or survival in rat cerebrocortical neural progenitor cells (NPC). After stimulation of NPC with Activin A, phosphorylation and nuclear translocation of Smad 2/3 were induced. In proliferating NPC, Activin produced a significant decrease in cell area and also a discrete increase in the number of neurons in the presence of the mitogen Fibroblast Growth Factor 2. The percentages of cells incorporating BrdU, or positive for the undifferentiated NPC markers Nestin and Sox2, were unchanged after incubation with Activin. In differentiating conditions, continuous treatment with Activin A significantly increased the number of neurons without affecting astroglial differentiation or causing apoptotic death. In cells cultured by extended periods, Activin treatment produced further increases in the proportion of neurons, excluding premature cell cycle exit. In clonal assays, Activin significantly increased neuronal numbers per colony, supporting an instructive role. Activin-induced neurogenesis was dependent on activation of its receptors, since incubation with the type I receptor inhibitor SB431542 or the ligand-trap Follistatin prevented neuronal differentiation. Interestingly, SB431542 or Follistatin by themselves abolished neurogenesis and increased astrogliogenesis, to a similar extent to that induced by Bone Morphogenetic Protein (BMP)4. Co-incubation of these Activin inhibitors with the BMP antagonist Dorsomorphin restored neuronal and astrocytic differentiation to control levels. CONCLUSIONS: Our results show an instructive neuronal effect of Activin A in cortical NPC in vitro, pointing out to a relevant role of this cytokine in the specification of NPC towards a neuronal phenotype.