RESUMO
Brain-derived neurotrophic factor (BDNF) is vital for synaptic plasticity, cell persistence, and neuronal development in peripheral and central nervous systems (CNS). Numerous intracellular signalling pathways involving BDNF are well recognized to affect neurogenesis, synaptic function, cell viability, and cognitive function, which in turn affects pathological and physiological aspects of neurons. Stroke has a significant psycho-socioeconomic impact globally. Central post-stroke pain (CPSP), also known as a type of chronic neuropathic pain, is caused by injury to the CNS following a stroke, specifically damage to the somatosensory system. BDNF regulates a broad range of functions directly or via its biologically active isoforms, regulating multiple signalling pathways through interactions with different types of receptors. BDNF has been shown to play a major role in facilitating neuroplasticity during post-stroke recovery and a pro-nociceptive role in pain development in the nervous system. BDNF-tyrosine kinase receptors B (TrkB) pathway promotes neurite outgrowth, neurogenesis, and the prevention of apoptosis, which helps in stroke recovery. Meanwhile, BDNF overexpression plays a role in CPSP via the activation of purinergic receptors P2X4R and P2X7R. The neuronal hyperexcitability that causes CPSP is linked with BDNF-TrkB interactions, changes in ion channels and inflammatory reactions. This review provides an overview of BDNF synthesis, interactions with certain receptors, and potential functions in regulating signalling pathways associated with stroke and CPSP. The pathophysiological mechanisms underlying CPSP, the role of BDNF in CPSP, and the challenges and current treatment strategies targeting BDNF are also discussed.
Assuntos
Fator Neurotrófico Derivado do Encéfalo , Acidente Vascular Cerebral , Humanos , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Animais , Acidente Vascular Cerebral/metabolismo , Acidente Vascular Cerebral/complicações , Neuralgia/metabolismo , Neuralgia/etiologia , Neuralgia/tratamento farmacológico , Receptor trkB/metabolismo , Transdução de Sinais/fisiologia , Plasticidade Neuronal/fisiologiaRESUMO
An advanced understanding of sperm function is relevant for evidence-based male fertility prediction and addressing male infertility. A standard breeding soundness evaluation (BSE) merely identifies gross abnormalities in bulls, whereas selection based on single nucleotide polymorphisms and genomic estimated breeding values overlooks sub-microscopic differences in sperm. Molecular tools are important for validating genomic selection and advancing knowledge on the regulation of male fertility at an interdisciplinary level. Therefore, research in this field is now focused on developing a combination of in vitro sperm function tests and identifying biomarkers such as sperm proteins with critical roles in fertility. The Na+-K+ ATPase is a ubiquitous transmembrane protein and its α4 isoform (ATP1A4) is exclusively expressed in germ cells and sperm. Furthermore, ATP1A4 is essential for male fertility, as it interacts with signaling molecules in both raft and non-raft fractions of the sperm plasma membrane to regulate capacitation-associated signaling, hyperactivation, sperm-oocyte interactions, and activation. Interestingly, ATP1A4 activity and expression increase during capacitation, challenging the widely accepted dogma of sperm translational quiescence. This review discusses the literature on the role of ATP1A4 during capacitation and fertilization events and its prospective use in improving male fertility prediction.
Assuntos
ATPase Trocadora de Sódio-Potássio , Testículo , Animais , Bovinos , Fertilidade/genética , Masculino , Isoformas de Proteínas/metabolismo , Sêmen/metabolismo , ATPase Trocadora de Sódio-Potássio/genética , ATPase Trocadora de Sódio-Potássio/metabolismo , Motilidade dos Espermatozoides , Espermatozoides/metabolismo , Testículo/metabolismoRESUMO
The plasma membrane of sperm contains highly dynamic lipid microdomains (rafts), which house signaling proteins with a role in regulating capacitation. We reported that ATP1A4, the testis-specific isoform of Na/K-ATPase, interacted with caveolin-1, Src, epidermal growth factor receptor (EGFR) and extracellular signal-regulated kinases 1/2 (ERK1/2) in raft and non-raft domains of the plasma membrane of bovine sperm during capacitation. The objective of the present study was to use a proteomic approach to characterize the ATP1A4 interactome in rafts and non-rafts from capacitated bovine sperm. The non-raft interactome included hexokinase 1, plakophilin 1, desmoglein 1, 14-3-3 protein ζ/δ, cathepsin D and heat shock protein beta1 proteins exclusively, whereas glutathione S-transferase and annexin A2 were unique to raft interactome. However, a disintegrin and metalloprotease 32 (ADAM 32), histone H4, actin, acrosin, serum albumin and plakoglobin were identified in both raft and non-raft fractions of capacitated sperm. Based on gene ontology studies, these differentially interacted proteins were implicated in cell-cell adhesion, signal transduction, fertilization, metabolism, proteolysis and DNA replication, in addition to acting as transport/carrier and cytoskeletal proteins. Overall, we identified proteins not previously reported to interact with ATP1A4; furthermore, we inferred that ATP1A4 may have a role in sperm capacitation.
Assuntos
Microdomínios da Membrana/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Espermatozoides/metabolismo , Animais , Anexina A2/metabolismo , Catepsina D/metabolismo , Bovinos , Desmogleínas/metabolismo , Glutationa Transferase/metabolismo , Proteínas de Choque Térmico/metabolismo , Hexoquinase/metabolismo , Isoenzimas/genética , Isoenzimas/metabolismo , Masculino , Placofilinas/metabolismo , Ligação Proteica , ATPase Trocadora de Sódio-Potássio/genéticaRESUMO
Interaction of Na/K-ATPase with its ligand ouabain has been implicated in the regulation of various biological processes. The objective was to investigate roles of Na/K-ATPase isoforms in formation and function of junctional complexes in Sertoli cells. Primary cultures of Sertoli cells were obtained by enzymatic digestion of 20-day-old rat testes and grown on Matrigel-coated dishes for 7 days. Sertoli cells predominantly expressed the ubiquitous isoform of Na/K-ATPase (ATP1A1), confirmed by immunoblotting, PCR, immunofluorescence, and mass spectrometry. Treatment of Sertoli cells with 50 nM ouabain increased transepithelial electrical resistance (TER) and expression of claudin 11 (tight junctions) and connexin 43 (gap junctions), whereas 1 mM ouabain had opposite effects. Involvement of Src-EGFR-ERK1/2-CREB pathway in ouabain-mediated expression of claudin 11 and connexin 43 was evaluated. Incubation of Sertoli cells with 50 nM ouabain increased content of p-Src, p-EGFR, p-ERK1/2, and p-CREB; in contrast, 1 mM ouabain decreased phosphorylation of these signaling molecules. Preincubation of Sertoli cells with inhibitors of Src and MAPK pathways inhibited ouabain-induced effects on these signaling molecules, TER, and expression of claudin 11 and connexin 43. In conclusion, we inferred that ATP1A1 regulated Sertoli cell tight junctions and gap junctions through the Src-EGFR-ERK1/2-CREB pathway. Ouabain is an endogenous steroid; therefore, its interaction with ATP1A1 may be a critical signaling mechanism for the regulation of Sertoli cell function and male fertility.
Assuntos
Claudinas/metabolismo , Conexina 43/metabolismo , Receptores ErbB/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Quinases da Família src/metabolismo , Animais , Claudinas/genética , Conexina 43/genética , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/genética , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Receptores ErbB/genética , MAP Quinases Reguladas por Sinal Extracelular/genética , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Regulação da Expressão Gênica/fisiologia , Masculino , Ratos , Ratos Sprague-Dawley , Células de Sertoli/fisiologia , ATPase Trocadora de Sódio-Potássio/química , ATPase Trocadora de Sódio-Potássio/genética , Quinases da Família src/genéticaRESUMO
Capacitation comprises a series of structural and functional modifications of sperm that confer fertilizing ability. We previously reported that the testis-specific isoform of Na/K-ATPase (ATP1A4) regulated bovine sperm capacitation through signaling mechanisms involving kinases. During subsequent investigations to elucidate mechanisms by which ATP1A4 regulates sperm capacitation, we observed that ATP1A4 was localised in both raft and non-raft fractions of the sperm plasma membrane and that its total content was increased in both membrane fractions during capacitation. The objective of the present study was to investigate mechanism(s) of capacitation-associated increase in the content of ATP1A4. Despite the widely accepted dogma of transcriptional/translational quiescence, incubation of sperm with either ouabain (specific ligand for ATP1A4) or heparin increased ATP1A4 content in raft and non-raft sperm membrane fractions, total sperm protein extracts (immunoblotting) and fixed sperm (flow cytometry), with a concurrent increase in Na/K-ATPase enzyme activity. This capacitation-associated increase in ATP1A4 content was partially decreased by chloramphenicol (mitochondrial translation inhibitor) but not affected by actinomycin D (transcription inhibitor). To demonstrate de novo ATP1A4 synthesis, we evaluated incorporation of bodipy conjugated lysine in this protein during capacitation. A partial decrease in bodipy-lysine incorporation occurred in ATP1A4 from sperm capacitated in the presence of chloramphenicol. Therefore, increased ATP1A4 content during capacitation was attributed to mitochondrial translation of ATP1A4 mRNA present in ejaculated sperm, rather than gene transcription. To our knowledge, this is the first report demonstrating ATP1A4 synthesis during bovine sperm capacitation.
Assuntos
Ribossomos Mitocondriais/metabolismo , Biossíntese de Proteínas , ATPase Trocadora de Sódio-Potássio/metabolismo , Capacitação Espermática , Testículo/metabolismo , Aminoácidos/metabolismo , Animais , Bovinos , Cloranfenicol/farmacologia , Dactinomicina/farmacologia , Detergentes/farmacologia , Citometria de Fluxo , Fluorescência , Gangliosídeo G(M1)/metabolismo , Isoenzimas/metabolismo , Masculino , Microdomínios da Membrana/metabolismo , Ribossomos Mitocondriais/efeitos dos fármacos , Especificidade de Órgãos/efeitos dos fármacos , Fosfoproteínas/metabolismo , Biossíntese de Proteínas/efeitos dos fármacos , Reprodutibilidade dos Testes , Solubilidade , Capacitação Espermática/efeitos dos fármacos , Frações Subcelulares/efeitos dos fármacos , Frações Subcelulares/metabolismo , Testículo/efeitos dos fármacosRESUMO
Highly dynamic lipid microdomains (rafts) in the sperm plasma membrane contain several signaling proteins that regulate sperm capacitation. Na/K-ATPase isoforms (testis-specific isoform ATP1A4 and ubiquitous isoform ATP1A1) are abundant in bovine sperm plasma membrane. We previously reported that incubation of bovine sperm with ouabain, a specific Na/K-ATPase ligand, induced tyrosine phosphorylation of several sperm proteins during capacitation. The objective of this study was to investigate the roles of lipid rafts and non-rafts in Na/K-ATPase enzyme activity and signaling during bovine sperm capacitation. Content of ATP1A4 and, to a lesser extent, ATP1A1 was increased in raft and non-raft fractions of capacitated sperm, although non-raft enzyme activities of both isoforms were higher than the corresponding activities in rafts from capacitated sperm. Yet, ATP1A4 was the predominant isoform responsible for total Na/K-ATPase activity in both rafts and non-rafts. A comparative increase in phosphorylation of signaling molecules was observed in both raft (CAV1) and non-raft (EGFR and ERK1/2) membrane fractions during capacitation. Although SRC was phosphorylated in both membrane fractions, the non-raft fraction possessed more of this activated form. We also inferred, by immunoprecipitation, that ATP1A4 interacted with CAV1 and EGFR in the raft fraction, whereas interactions of ATP1A4 with SRC, EGFR, and ERK1/2 occurred in the non-raft fraction of ouabain-capacitated sperm; conversely, ATP1A1 interacted only with CAV1 in both fractions of uncapacitated and capacitated sperm. In conclusion, both raft and non-raft cohorts of Na/K-ATPase isoforms contributed to phosphorylation of signaling molecules during bovine sperm capacitation.
Assuntos
Sistema de Sinalização das MAP Quinases/fisiologia , Microdomínios da Membrana/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Capacitação Espermática/fisiologia , Espermatozoides/metabolismo , Animais , Bovinos , Masculino , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Espermatozoides/citologiaRESUMO
Our objectives were to examine changes in endometrial and luteal gene expression during estrus, diestrus, pregnancy and treatments to induce luteolysis and putatively induce luteostasis. Groups were: Diestrus (DIEST), Estrus (ESTR), Pregnant (PREG), Oxytocin (OXY), Carbetocin (CARB), and Meclofenamic acid (MFA). Blood was obtained from day (D)12 to D15 for measurement of oxytocinase, also referred to as leucyl-cysteinyl aminopeptidase (LNPEP) and progesterone. Luteal biopsies were obtained on D12 and D15 and an endometrial biopsy on D15. Real-time RT-PCR was performed for the following genes: PGR, ESR1, OXTR,OXT, LNPEP, PTGS2, PTGFR, PLA2G2C, PTGES, SLC2A4, and SLC2A1. Regarding serum LNPEP, PREG and OXY (p-value<0.001) had higher concentrations than DIEST mares. Endometrial PTGES expression was higher (p-value <0.04) in DIEST, PREG and OXY than other groups. Endometrium from ESTR had increased expression of OXT (p-value < 0.02) compared to MFA and OXY mares. Carbetocin treatment: decreased serum progesterone and LNPEP; increased endometrial PLA2G2C; decreased endometrial PTGES; and decreased luteal aromatase and PTGES. Treatment with MFA: decreased endometrial PLA2G2C, increased endometrial PTGES; and resulted in less OXTR and OXT luteal abundance on D12 compared to D15. Endometrial and luteal expression of LNPEP is affected by physiologic stage and treatment and is involved in luteal function and pregnancy recognition pathways through effects on oxytocin and prostaglandin synthesis in the horse.
Assuntos
Ocitocina , Progesterona , Gravidez , Cavalos , Animais , Feminino , Ocitocina/metabolismo , Ácido Meclofenâmico/metabolismo , Cistinil Aminopeptidase/metabolismo , Corpo Lúteo/fisiologia , Expressão Gênica , Endométrio/metabolismoRESUMO
Our understanding of the temporal changes in endometrial and luteal gene transcripts related to the actions of oxytocin and prostaglandin during early equine pregnancy is incomplete. Additionally, the role of oxytocinase, also known as Leucyl-cystinyl aminopeptidase (LNPEP), during early pregnancy in mares has not been previously investigated. Luteal and endometrial biopsies were obtained on Day (D)8, D10, D12 and D15 post-ovulation in pregnant (PREG) and diestrus (DIEST) mares for real-time qPCR. Differences in endometrial gene expression occurred over time in: SLC2A4, SLC2A1, PTGES, OXTR and LNPEP. PTGFR and PLA2G2C had lower relative abundance in PREG D15 endometrium compared to D10. OXT and OXTR were increased on D10 and 15 PREG, respectively. Regarding luteal mRNA relative abundance, ESR1, PTGS2, PTGFR, and PTGES had higher relative abundance in D12 of DIEST and PREG. Luteal expression of OXTR and OXT had higher relative abundance in D15 compared to D8, and LNPEP had higher relative abundance in D10 and 12. Endometrial and luteal PTGES had an increased mRNA abundance in both D12 DIEST and PREG mares, which may lead to additional luteoprotective prostaglandin E2 (PGE2) secretion. Furthermore, luteal SLC2A1 had higher relative abundance in pregnancy, and likely supports the high metabolic activity of luteal tissue by increasing glucose uptake. Oxytocinase is present in endometrial and luteal tissue and its role in oxytocin induced prostaglandin secretion is uncertain.
Assuntos
Dinoprostona , Ocitocina , Animais , Ciclo-Oxigenase 2/metabolismo , Cistinil Aminopeptidase/genética , Cistinil Aminopeptidase/metabolismo , Dinoprostona/metabolismo , Endométrio/metabolismo , Feminino , Expressão Gênica , Glucose/metabolismo , Cavalos/genética , Ocitocina/farmacologia , Gravidez , Prostaglandinas/metabolismo , RNA Mensageiro/metabolismoRESUMO
A standard bull breeding soundness evaluation (BBSE) identifies bulls with semen that is grossly abnormal. Nonetheless, semen samples classified as satisfactory based on these traditional approaches differ in fertility; perhaps there are submicroscopic differences in sperm characteristics affecting fertility. Therefore, a better understanding of molecular regulation of sperm function could promote development of novel, evidence-based approaches to predict male fertility. Recently the α4 isoform of Na/K-ATPase (ATP1A4) has received considerable attention, due to its testis- specific expression in post-meiotic germ cells and mature sperm, in addition to its regulation of sperm motility and capacitation. Using fresh bull sperm, we determined that ATP1A4 resided in specialized microdomains (raft and non-raft) of the sperm plasma membrane and activated specific signaling (caveolin-1, EGFR, Src, ERK1/2) molecules during sperm capacitation. Furthermore, ATP1A4 was the predominant isoform responsible for total Na/K-ATPase activity in capacitated sperm. Despite the widely accepted dogma of transcriptional/translational quiescence, bovine sperm translated ATP1A4 mRNA on mitochondrial or mitochondrial-type ribosomes, increasing their content and activity during capacitation. Proteomic analysis of raft and non-raft fractions revealed a significant interaction between ATP1A4 and plakoglobin, a member of the ß-catenin family of proteins involved in cell adhesion, in the equatorial segment of capacitated sperm, suggesting a potential role in sperm-oolemma fusion. In frozen-thawed sperm, ATP1A4 content and activity was greater in high- versus low-fertility bulls. Additionally, ATP1A4-induced increases in ROS, calcium, actin polymerization and tyrosine phosphorylation were also involved in regulating post-thaw sperm function in these bulls. Overall, results demonstrated that ATP1A4 had unique roles in controlling several aspects of sperm physiology, acting through well-established enzyme activity and signaling functions. Consequently, isoforms of Na/K-ATPase are potential biomarkers for male fertility.
RESUMO
The objective was to investigate expression patterns of proteins in pyriform sperm, a common morphological abnormality in bull sperm. Ejaculates were collected from sexually mature Holstein bulls (n=3) twice weekly for 10 weeks (pre-thermal insult samples). Testicular temperature was elevated in all bulls by scrotal insulation for 72 consecutive hours during week 2. Total sperm proteins were extracted from pre- and post-thermal insult sperm samples and subjected to two-dimensional gel electrophoresis. Among the protein spots detected, 131 spots were significantly expressed (False Detection Rate <0.01) with ≥ 2 fold changes between normal and pyriform sperm. Among them, 25 spots with ≥ 4 fold difference in expression patterns were identified using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Expression of several proteins involved in sperm capacitation, sperm-egg interaction and sperm cytoskeletal structure was decreased in pyriform sperm, whereas proteins regulating antioxidant activity, apoptosis and metabolic activity were increased. Contents of reactive oxygen species and ubiquitinated proteins were higher in pyriform sperm. In addition to understanding the molecular basis of functional deficiencies in sperm with specific morphological abnormalities, comparing normal versus morphologically abnormal sperm appeared to be a suitable experimental model for identifying important sperm functional proteins. BIOLOGICAL SIGNIFICANCE: To our knowledge, this study is the first report on differential expression of proteins in pyriform bovine sperm versus morphologically normal sperm. We report that expression of several proteins involved in sperm capacitation, sperm-egg interaction and sperm cytoskeletal structure was decreased in pyriform sperm, whereas proteins which regulate antioxidant activity, apoptosis and metabolic activity were increased. Contents of reactive oxygen species and ubiquitinated proteins were higher in pyriform sperm. In addition to understanding the molecular basis of functional deficiencies in sperm with specific morphological abnormalities, our results suggest that comparing normal versus morphologically abnormal sperm appeared to be a suitable experimental model for identifying important sperm functional proteins.