scholarly journals Possible mechanisms underlying the dynamic assembly of calcium entry units: The role of temperature and pH

2021 ◽  
Vol 154 (9) ◽  
Author(s):  
Barbara Girolami ◽  
Matteo Serano ◽  
Laura Pietrangelo ◽  
Feliciano Protasi
Keyword(s):  
Molecular Mechanisms ◽  
Prolonged Exercise ◽  
Ex Vivo ◽  
Calcium Entry ◽  
Skeletal Muscle Function ◽  
Fatigue Protocol ◽  
Ec Coupling ◽  
Dynamic Assembly ◽  
Higher Temperature

Skeletal muscle function is regulated by intracellular Ca2+ levels. Two main mechanisms control movements of Ca2+ ions from intracellular stores (i.e., the sarcoplasmic reticulum; SR) and from extracellular space: (1) excitation–contraction (EC) coupling and (2) store-operated Ca2+ entry (SOCE). SOCE allows recovery of extracellular Ca2+ during prolonged muscle activity, when the SR undergoes depletion. We recently discovered that prolonged exercise leads to formation of calcium entry units (CEUs), intracellular junctions located at the I band that are formed by two distinct elements: SR stacks and transverse tubules (TTs). Assembly of CEUs during exercise promotes the interaction between STIM1 and Orai1, the two main proteins that mediate SOCE, and increases muscle resistance to fatigue in the presence of extracellular Ca2+. The molecular mechanisms underlying the exercise-dependent remodeling of SR and TT leading to CEU assembly remain to be fully elucidated. Here, we first verified whether CEUs can assemble ex vivo (in the absence of blood supply and innervation), subjecting excised EDL muscles from mice to an ex vivo incremental fatigue protocol (80 Hz tetanus stimulation lasting 45 min): the data collected demonstrate that CEUs can assemble ex vivo in isolated EDL muscles. We then evaluated if intracellular parameters that are affected by exercise, such as temperature and pH, may influence the assembly of CEUs. We found that higher temperature (36°C versus 25°C) and lower pH (7.2 versus 7.4) promotes formation of CEUs increasing the percentage of fibers containing SR stacks, the number of SR stacks/area, and the elongation of TTs at the I band. Importantly, increased assembly of CEUs at higher temperature (36°C) or at lower pH (7.2) correlated with increased fatigue resistance of EDL muscles in the presence of extracellular Ca2+, suggesting that CEUs assembled ex vivo are functional.

scholarly journals Role of Insulin Receptor Substrate-1 Serine 307 Phosphorylation and Adiponectin in Adipose Tissue Insulin Resistance in Late Pregnancy

Endocrinology ◽  
2007 ◽  
Vol 148 (12) ◽  
pp. 5933-5942 ◽  
Author(s):  
Julio Sevillano ◽  
Javier de Castro ◽  
Carlos Bocos ◽  
Emilio Herrera ◽  
M. Pilar Ramos
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Insulin Receptor ◽  
Tyrosine Phosphorylation ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Late Pregnancy ◽  
Serine Phosphorylation ◽  
Pregnant Rats

Insulin resistance is a hallmark of late pregnancy both in human and rat. Adipose tissue is one of the tissues that most actively contributes to this reduced insulin sensitivity. The aim of the present study was to characterize the molecular mechanisms of insulin resistance in adipose tissue at late pregnancy. To this end, we analyzed the insulin signaling cascade in lumbar adipose tissue of nonpregnant and pregnant (d 20) rats both under basal and insulin-stimulated conditions. We found that the levels of relevant signaling proteins, such as insulin receptor (IR), IR substrate-1 (IRS-1), phosphatidylinositol 3-kinase, 3-phosphoinositide-dependent kinase-1, ERK1/2, and phosphatase and tensin homolog (PTEN) did not change at late pregnancy. However, insulin-stimulated tyrosine phosphorylation of both IR and IRS-1 were significantly decreased, coincident with decreased IRS-1/p85 association and impaired phosphorylation of AKR mouse thymoma viral protooncogene (Akt) and ERK1/2. This impaired activation of IRS-1 occurred together with an increase of IRS-1 phosphorylation at serine 307 and a decrease in adiponectin levels. To corroborate the role of IRS-1 in adipose tissue insulin resistance during pregnancy, we treated pregnant rats with the antidiabetic drug englitazone. Englitazone improved glucose tolerance, and this pharmacological reversal of insulin resistance was paralleled by an increase of adiponectin levels in adipose tissue as well as by a reduction of IRS-1 serine phosphorylation. Furthermore, the impaired insulin-stimulated tyrosine phosphorylation of IRS-1 in adipose tissue of pregnant animals could be restored ex vivo by treating isolated adipocytes with adiponectin. Together, our findings support a role for adiponectin and serine phosphorylation of IRS-1 in the modulation of insulin resistance in adipose tissue at late pregnancy.

Rhodiola and salidroside in the treatment of metabolic disorders

2019 ◽  
Vol 19 (19) ◽  
pp. 1611-1626 ◽  
Author(s):  
Xiang-Li Bai ◽  
Xiu-Ling Deng ◽  
Guang-Jie Wu ◽  
Wen-Jing Li ◽  
Si Jin
Keyword(s):  
Metabolic Disorders ◽  
Energy Homeostasis ◽  
Molecular Mechanisms ◽  
Metabolic Diseases ◽  
Ex Vivo ◽  
Treatment Strategies ◽  
Ampk Signaling ◽  
Beneficial Effects

Over the past three decades, the knowledge gained about the mechanisms that underpin the potential use of Rhodiola in stress- and ageing-associated disorders has increased, and provided a universal framework for studies that focused on the use of Rhodiola in preventing or curing metabolic diseases. Of particular interest is the emerging role of Rhodiola in the maintenance of energy homeostasis. Moreover, over the last two decades, great efforts have been undertaken to unravel the underlying mechanisms of action of Rhodiola in the treatment of metabolic disorders. Extracts of Rhodiola and salidroside, the most abundant active compound in Rhodiola, are suggested to provide a beneficial effect in mental, behavioral, and metabolic disorders. Both in vivo and ex vivo studies, Rhodiola extracts and salidroside ameliorate metabolic disorders when administered acutely or prior to experimental injury. The mechanism involved includes multi-target effects by modulating various synergistic pathways that control oxidative stress, inflammation, mitochondria, autophagy, and cell death, as well as AMPK signaling that is associated with possible beneficial effects on metabolic disorders. However, evidence-based data supporting the effectiveness of Rhodiola or salidroside in treating metabolic disorders is limited. Therefore, a comprehensive review of available trials showing putative treatment strategies of metabolic disorders that include both clinical effective perspectives and fundamental molecular mechanisms is warranted. This review highlights studies that focus on the potential role of Rhodiola extracts and salidroside in type 2 diabetes and atherosclerosis, the two most common metabolic diseases.

scholarly journals Novel Role of UHRF1 in DNA methylation-mediated repression of latent HIV-1

2021 ◽  
Author(s):  
Roxane Verdikt ◽  
Sophie Bouchat ◽  
Alexander O. Pasternak ◽  
Lorena Nestola ◽  
Gilles Darcis ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Proof Of Concept ◽  
Methylation Inhibitor ◽  
Dna Methylation Inhibitor ◽  
Latent Hiv ◽  
Hiv 1 ◽  
Patient Cell

The multiplicity, heterogeneity and dynamic nature of HIV-1 latency mechanisms are reflected in the current lack of functional cure for HIV-1 and in the various reported ex vivo potencies of latency-reversing agents. Here, we investigated the molecular mechanisms underlying the potency of the DNA methylation inhibitor 5-aza-2'-deoxycytidine (5-AzadC) in HIV-1 latency reversal. Doing so, we uncovered specific demethylation CpG signatures induced by 5-AzadC in the HIV-1 promoter. By analyzing the binding modalities to these CpG, we revealed the recruitment of the epigenetic integrator UHRF1 to the HIV-1 promoter. We further demonstrated the role of UHRF1 in DNA methylation-mediated silencing of the latent HIV-1 promoter. As a proof-of-concept to this molecular characterization, we showed that pharmacological downregulation of UHRF1 in ex vivo HIV+ patient cell cultures resulted in potent reactivation of latent HIV-1. Together, we identify UHRF1 as a novel actor in HIV-1 gene silencing and highlight that it constitutes a new molecular target for HIV-1 curative strategies.

scholarly journals The Role of DOT1L Methyltransferase Activity in Fetal Hematopoiesis

2020 ◽  
Author(s):  
Carrie A. Malcom ◽  
Joanna Piaseka-Srader ◽  
V. Praveen Chakravarthi ◽  
Shaon Borosha ◽  
Anamika Ratri ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Mutant Mouse ◽  
Ex Vivo ◽  
Hematopoietic Differentiation ◽  
Wild Type ◽  
Hematopoietic Progenitors ◽  
Methyltransferase Activity ◽  
Mutant Mouse Line ◽  
Fetal Hematopoiesis

ABSTRACTEarly mammalian erythropoiesis requires the DOT1L methyltransferase. We demonstrated that loss of DOT1L in mutant mice resulted in lethal anemia during midgestation. The molecular mechanisms by which DOT1L regulates embryonic erythropoiesis have not yet been elucidated. In this study, a methyltransferase mutant mouse line (Dot1L-MM) was generated to determine whether the methyltransferase activity of DOT1L is essential for erythropoiesis. Dot1L-MM mice displayed embryonic lethality between embryonic days 10.5 and 13.5, similar to Dot1lL knockout (Dot1L-KO) mice. However, when examined at E10.5, unlike the Dot1L-KO, Dot1L-MM embryos did not exhibit evidence of anemia. In ex vivo hematopoietic differentiation cultures, Dot1L-KO and Dot1L-MM yolk sac (YS) cells both formed reduced numbers of myeloid, and mixed hematopoietic colonies. Erythroid colonies were able to be formed in numbers equal to wildtype embryos. Extensively self-renewing erythroblast (ESRE) cultures were established using YS cells from E10.5 embryos. Dot1L-KO and Dot1L-MM cells expanded significantly less than wild-type cells and exhibited increased cell death. Strikingly, Dot1L-KO and Dot1L-MM cells of YS origin exhibited profound genomic instability, implicating DOT1L methyltransferase activity in maintenance of the genome as well as viability of hematopoietic progenitors. Our results indicate that the methyltransferase activity of DOT1L plays an important role early murine hematopoiesis.

scholarly journals A Matter of Choice: Inhibition of c-Rel Shifts Neuronal to Oligodendroglial Fate in Human Stem Cells

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 1037 ◽  
Author(s):  
Lucia Mercedes Ruiz-Perera ◽  
Johannes Friedrich Wilhelm Greiner ◽  
Christian Kaltschmidt ◽  
Barbara Kaltschmidt
Keyword(s):  
Stem Cells ◽  
Molecular Mechanisms ◽  
Neuronal Development ◽  
Therapeutic Potential ◽  
Ex Vivo ◽  
Transcript Level ◽  
Human Stem Cells ◽  
Human Neural Stem Cells ◽  
Essential Function

The molecular mechanisms underlying fate decisions of human neural stem cells (hNSCs) between neurogenesis and gliogenesis are critical during neuronal development and neurodegenerative diseases. Despite its crucial role in the murine nervous system, the potential role of the transcription factor NF-κB in the neuronal development of hNSCs is poorly understood. Here, we analyzed NF-κB subunit distribution during glutamatergic differentiation of hNSCs originating from neural crest-derived stem cells. We observed several peaks of specific NF-κB subunits. The most prominent nuclear peak was shown by c-REL subunit during a period of 2–5 days after differentiation onset. Furthermore, c-REL inhibition with pentoxifylline (PTXF) resulted in a complete shift towards oligodendroglial fate, as demonstrated by the presence of OLIG2+/O4+-oligodendrocytes, which showed PDGFRα, NG2 and MBP at the transcript level. In addition c-REL impairment further produced a significant decrease in neuronal survival. Transplantation of PTXF-treated predifferentiated hNSCs into an ex vivo oxidative-stress-mediated demyelination model of mouse organotypic cerebellar slices further led to integration in the white matter and differentiation into MBP+ oligodendrocytes, validating their functionality and therapeutic potential. In summary, we present a human cellular model of neuronal differentiation exhibiting a novel essential function of NF-κB-c-REL in fate choice between neurogenesis and oligodendrogenesis which will potentially be relevant for multiple sclerosis and schizophrenia.

scholarly journals The mechanosensitive ion channel Piezo2 mediates sensitivity to mechanical pain in mice

2018 ◽  
Vol 10 (462) ◽  
pp. eaat9897 ◽  
Author(s):  
Swetha E. Murthy ◽  
Meaghan C. Loud ◽  
Ihab Daou ◽  
Kara L. Marshall ◽  
Frederick Schwaller ◽  
...  
Keyword(s):  
Nerve Injury ◽  
Sensory Neurons ◽  
Mechanical Allodynia ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Mechanical Stimuli ◽  
C Fiber ◽  
Mechanosensitive Ion Channel ◽  
Deficient Mice

The brush of a feather and a pinprick are perceived as distinct sensations because they are detected by discrete cutaneous sensory neurons. Inflammation or nerve injury can disrupt this sensory coding and result in maladaptive pain states, including mechanical allodynia, the development of pain in response to innocuous touch. However, the molecular mechanisms underlying the alteration of mechanical sensitization are poorly understood. In mice and humans, loss of mechanically activated PIEZO2 channels results in the inability to sense discriminative touch. However, the role of Piezo2 in acute and sensitized mechanical pain is not well defined. Here, we showed that optogenetic activation ofPiezo2-expressing sensory neurons induced nociception in mice. Mice lackingPiezo2in caudal sensory neurons had impaired nocifensive responses to mechanical stimuli. Consistently, ex vivo recordings in skin-nerve preparations from these mice showed diminished Aδ-nociceptor and C-fiber firing in response to mechanical stimulation. Punctate and dynamic allodynia in response to capsaicin-induced inflammation and spared nerve injury was absent in Piezo2-deficient mice. These results indicate that Piezo2 mediates inflammation- and nerve injury–induced sensitized mechanical pain, and suggest that targeting PIEZO2 might be an effective strategy for treating mechanical allodynia.

Abstract MP150: Inositol 1,4,5-trisphosphate Receptors Selectively Regulate Detrimental Cardiac Fibrosis by Modulating ER-phagy

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Gaetano Santulli ◽  
Marco Morelli ◽  
Xujun Wang ◽  
John Ferrante ◽  
Jessica Gambardella
Keyword(s):  
Molecular Mechanisms ◽  
Cardiac Fibrosis ◽  
Ex Vivo ◽  
Myocardial Dysfunction ◽  
Association Studies ◽  
Experimental Studies ◽  
Genome Wide Association Studies ◽  
Inositol 1,4,5 Trisphosphate

Background: Therapeutic strategies that specifically target excessive post-ischemic cardiac fibrosis are lacking but desperately needed; thus, it is critical to understand the molecular mechanisms underlying these processes. Genome-wide association studies have revealed an association between inositol 1,4,5-trisphosphate receptors (IP3Rs) and ischemic heart disease. However, experimental studies examining the exact role of IP3Rs in post-ischemic cardiac fibrosis are missing. Aim: We hypothesize that IP3Rs play a key role in the regulation of cardiac myofibroblasts (myoFBs) in healing the infarcted heart after myocardial infarction (MI). Methods: We performed an integrated set of in vivo, ex vivo , and in vitro experiments aiming at identifying the functional role of cardiac myoFB IP3Rs in post-ischemic cardiac remodeling. We generated cardiac myo-FB-specific Triple IP3R knock-out (IP3R TKO ) mice ( Cre/lox recombination technique; Promoter: Periostin ), allowing us to overcome the difficulties encountered following the KO or KD of a single (of the three existent) IP3Rs, a strategy that has been shown to induce compensatory upregulation of the other isoforms. Results: After MI, IP3Rs are significantly upregulated in myoFBs of the remote regions but not in the scar area. IP3R TKO mice display a significantly reduced interstitial cardiac fibrosis and a markedly attenuated myocardial dysfunction following MI compared with control IP3R flox or Periostin Cre littermates. Moreover, FBs lacking IP3Rs exhibit significantly reduced migratory and secretory capacities, a finding confirmed both in murine and human FBs. Mechanistically, we show that IP3Rs modulate endoplasmic reticulum autophagy (ER-phagy) in primary isolated myoFBs following ischemic injury. Conclusions: Taken together, our findings indicate for the first time that IP3Rs are essential for the regulation of post-ischemic cardiac fibrosis.

scholarly journals Histone acetyltransferase and Polo-like kinase 3 inhibitors prevent rat galactose-induced cataract

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Fumito Kanada ◽  
Yoshihiro Takamura ◽  
Seiji Miyake ◽  
Kazuma Kamata ◽  
Mayumi Inami ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Histone Acetyltransferase ◽  
Ex Vivo ◽  
Causative Factor ◽  
Mrna Levels ◽  
Cataract Formation ◽  
Diabetic Cataract ◽  
Novel Approach ◽  
Hat Inhibitor

AbstractDiabetic cataracts can occur at an early age, causing visual impairment or blindness. The detailed molecular mechanisms of diabetic cataract formation remain incompletely understood, and there is no well-documented prophylactic agent. Galactose-fed rats and ex vivo treatment of lenses with galactose are used as models of diabetic cataract. To assess the role of histone acetyltransferases, we conducted cataract prevention screening with known histone acetyltransferase (HAT) inhibitors. Ex vivo treatment with a HAT inhibitor strongly inhibited the formation of lens turbidity in high-galactose conditions, while addition of a histone deacetylase (HDAC) inhibitor aggravated turbidity. We conducted a microarray to identify genes differentially regulated by HATs and HDACs, leading to discovery of a novel cataract causative factor, Plk3. Plk3 mRNA levels correlated with the degree of turbidity, and Plk3 inhibition alleviated galactose-induced cataract formation. These findings indicate that epigenetically controlled Plk3 influences cataract formation. Our results demonstrate a novel approach for prevention of diabetic cataract using HAT and Plk3 inhibitors.

How do histone modifications contribute to transgenerational epigenetic inheritance in C. elegans?

2020 ◽  
Vol 48 (3) ◽  
pp. 1019-1034 ◽  
Author(s):  
Rachel M. Woodhouse ◽  
Alyson Ashe
Keyword(s):  
Histone Modifications ◽  
Molecular Mechanisms ◽  
Epigenetic Inheritance ◽  
Nematode Caenorhabditis Elegans ◽  
Histone Methyltransferases ◽  
Transgenerational Epigenetic Inheritance ◽  
C Elegans ◽  
Recent Developments ◽  
Gene Regulatory

Gene regulatory information can be inherited between generations in a phenomenon termed transgenerational epigenetic inheritance (TEI). While examples of TEI in many animals accumulate, the nematode Caenorhabditis elegans has proven particularly useful in investigating the underlying molecular mechanisms of this phenomenon. In C. elegans and other animals, the modification of histone proteins has emerged as a potential carrier and effector of transgenerational epigenetic information. In this review, we explore the contribution of histone modifications to TEI in C. elegans. We describe the role of repressive histone marks, histone methyltransferases, and associated chromatin factors in heritable gene silencing, and discuss recent developments and unanswered questions in how these factors integrate with other known TEI mechanisms. We also review the transgenerational effects of the manipulation of histone modifications on germline health and longevity.

Mesophyll conductance: the leaf corridors for photosynthesis

2020 ◽  
Vol 48 (2) ◽  
pp. 429-439 ◽  
Author(s):  
Jorge Gago ◽  
Danilo M. Daloso ◽  
Marc Carriquí ◽  
Miquel Nadal ◽  
Melanie Morales ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Main Role ◽  
Mesophyll Conductance ◽  
Future Studies ◽  
Cell Structures ◽  
Leaf Tissues ◽  
Change Framework ◽  
Chloroplast Stroma

Besides stomata, the photosynthetic CO2 pathway also involves the transport of CO2 from the sub-stomatal air spaces inside to the carboxylation sites in the chloroplast stroma, where Rubisco is located. This pathway is far to be a simple and direct way, formed by series of consecutive barriers that the CO2 should cross to be finally assimilated in photosynthesis, known as the mesophyll conductance (gm). Therefore, the gm reflects the pathway through different air, water and biophysical barriers within the leaf tissues and cell structures. Currently, it is known that gm can impose the same level of limitation (or even higher depending of the conditions) to photosynthesis than the wider known stomata or biochemistry. In this mini-review, we are focused on each of the gm determinants to summarize the current knowledge on the mechanisms driving gm from anatomical to metabolic and biochemical perspectives. Special attention deserve the latest studies demonstrating the importance of the molecular mechanisms driving anatomical traits as cell wall and the chloroplast surface exposed to the mesophyll airspaces (Sc/S) that significantly constrain gm. However, even considering these recent discoveries, still is poorly understood the mechanisms about signaling pathways linking the environment a/biotic stressors with gm responses. Thus, considering the main role of gm as a major driver of the CO2 availability at the carboxylation sites, future studies into these aspects will help us to understand photosynthesis responses in a global change framework.

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