Changes In Cellular Function Research Articles

Synergistic effects on mesenchymal stem cell-based cartilage regeneration by chondrogenic preconditioning and mechanical stimulation

BackgroundMesenchymal stem cells (MSCs) hold promising translational potential in cartilage regeneration. However, the efficacy of MSC-based tissue engineering is not satisfactory in the treatment of cartilage defect because of the inevitable cellular functional changes during ex vivo cell expansion. How to maintain the chondrogenic capacity of MSCs to improve their therapeutic outcomes remains an outstanding question.MethodsBone marrow-derived MSCs were firstly primed in chondrogenic induction medium which was then replaced with normal growth medium to attain the manipulated cells (M-MSCs). Methacrylated hyaluronic acid (MeHA) was synthesized as a scaffold to encapsulate the cells. The MSC- or M-MSC-laden constructs were treated with dynamic compressive loading (DL) in a bioreactor or with free loading (FL) for 14 days. Afterwards, the constructs were implanted in nude mice or rat models of osteochondral defects to test their efficiency in cartilage regeneration or repair.ResultsData showed that the resulting M-MSCs exhibited superior chondrogenic differentiation potential and survivability compared with untreated MSCs. More importantly, we found that DL significantly promoted neocartilage formation in the MeHA hydrogel encapsulated with M-MSCs after 30 days of implantation in nude mice. Furthermore, the constructs laden with M-MSCs after DL for 14 days significantly enhanced cartilage healing in a rat model of osteochondral defect.ConclusionsFindings from this study highlight the importance of maintaining chondrogenic potential of MSCs by in-vitro chondrogenic preconditioning and a synergistic effect of mechanical stimulation in cartilage engineering, which may shed light on the stem cell-based tissue engineering for cartilage repair.

Responsive monitoring of mitochondrial redox states in heart muscle predicts impending cardiac arrest.

Assessing the adequacy of oxygen delivery to tissues is vital, particularly in the fields of intensive care medicine and surgery. As oxygen delivery to a cell becomes deficient, changes in mitochondrial redox state precede changes in cellular function. We describe a technique for the continuous monitoring of the mitochondrial redox state on the epicardial surface using resonance Raman spectroscopy. We quantify the reduced fraction of specific electron transport chain cytochromes, a metric we name the resonance Raman reduced mitochondrial ratio (3RMR). As oxygen deficiency worsens, heme moieties within the electron transport chain become progressively more reduced, leading to an increase in 3RMR. Myocardial 3RMR increased from baseline values of 18.1 ± 5.9 to 44.0 ± 16.9% (P = 0.0039) after inferior vena cava occlusion in rodents (n = 8). To demonstrate the diagnostic power of this measurement, 3RMR was continuously measured in rodents (n = 31) ventilated with 5 to 8% inspired oxygen for 30 min. A 3RMR value exceeding 40% at 10 min predicted subsequent cardiac arrest with 95% sensitivity and 100% specificity [area under the curve (AUC), 0.98], outperforming all current measures, including contractility (AUC, 0.51) and ejection fraction (AUC, 0.39). 3RMR correlated with indices of intracellular redox state and energy production. This technique may permit the real-time identification of critical defects in organ-specific oxygen delivery.

Executing clinical proteomic studies using mass spectrometry

SummaryBiomarkers are tools of personalized medicine and potentially valuable end points for clinical studies. They can be used to measure a patient's risk to certain disease and the severity of the disease, and to predict and/or measure the patient's therapeutic response to treatment. Mass spectrometry (MS) enables simultaneous detection and quantification of most proteins, and therefore has become an attractive method for biomarker discovery in the recent years. It can be used to detect changes in cellular functions and metabolism in a more comprehensive way than the traditional immunoassays. In this presentation, the techniques used in sample preparation and MS will be demonstrated in a practical way. The presentation will cover methods used through the different phases of clinical proteomic studies from planning to discovery and validation of discovered biomarkers.

3D Microstructure Inhibits Mesenchymal Stem Cells Homing to the Site of Liver Cancer Cells on a Microchip.

The cell microenvironment consists of multiple types of biophysical and biochemical factors, and represents a complex integrated system that is variable in both time and space. Studies show that changes in biochemical and biophysical factors in cell microenvironments result in significant changes in cellular forms and functions, especially for stem cells. Mesenchymal stem cells (MSCs) are derived from adult stem cells of the mesoderm and play an important role in tissue engineering, regenerative medicine and even cancer therapy. Furthermore, it is found that MSCs can interact with multiple types of tumor cells. The interaction is reflected as two totally different aspects. The negative aspect is that MSCs manifest as tumor-associated fibroblasts and could induce migration of cancer cells and promote tumor formation. On the other hand, MSCs can home to sites of the tumor microenvironment, directionally migrate toward tumor cells and cause tumor cell apoptosis. In this study, we designed and made a simple microfluidic chip for cell co-culture, and studied stem cell homing behavior in the interaction between MSCs and liver cancer cells. Moreover, by etching a three-dimensional microstructure on the base and adding transforming growth factor-β (TGF-β) in the co-culture environment, we studied the impact of biophysical and biochemical factors on stem cell homing behavior, and the causes of such impact.

Deblurring Signal Network Dynamics.

To orchestrate the function and development of multicellular organisms, cells integrate intra- and extracellular information. This information is processed via signal networks in space and time, steering dynamic changes in cellular structure and function. Defects in those signal networks can lead to developmental disorders or cancer. However, experimental analysis of signal networks is challenging as their state changes dynamically and differs between individual cells. Thus, causal relationships between network components are blurred if lysates from large cell populations are analyzed. To directly study causal relationships, perturbations that target specific components have to be combined with measurements of cellular responses within individual cells. However, using standard single-cell techniques, the number of signal activities that can be monitored simultaneously is limited. Furthermore, diffusion of signal network components limits the spatial precision of perturbations, which blurs the analysis of spatiotemporal processing in signal networks. Hybrid strategies based on optogenetics, surface patterning, chemical tools, and protein design can overcome those limitations and thereby sharpen our view into the dynamic spatiotemporal state of signal networks and enable unique insights into the mechanisms that control cellular function in space and time.

Endoplasmic reticulum stress in the pathogenesis of hypertension.

What is the topic of this review? This review highlights the emerging role of disruptions in endoplasmic reticulum (ER) function, namely ER stress, as a contributor to hypertension. What advances does it highlight? This review presents an integrative view of ER stress in cardiovascular control systems, including systems within the brain, kidney and peripheral vasculature, as related to development of hypertension. The endoplasmic reticulum (ER) is a cellular organelle specialized in the synthesis, folding, assembly and modification of proteins. In situations of increased protein demand, complex signalling pathways, termed the unfolded protein response, influence a series of cellular feedback loops to control ER function strictly. Although this is initially a compensatory attempt to maintain cellular homeostasis, chronic activation of the unfolded protein response, known as ER stress, leads to sustained changes in cellular function. A growing body of literature points to ER stress in diverse cardioregulatory systems, including the brain, kidney and vasculature, as central to the development of hypertension. Here, these recent findings from essential and obesity-related forms of hypertension are highlighted in an integrative manner, with discussion of the potential upstream causes and downstream consequences of ER stress. Given that hypertension is a leading medical and socio-economic global challenge, emerging findings suggest that targeting ER stress might represent a viable strategy for the treatment of hypertensive disease.

Nano-bio compatibility of PEGylated reduced graphene oxide on mesenchymal stem cells

Graphene, with its unique physico-chemical properties, has found widespread biomedical application. It is used as a carrier for drug or gene delivery, photothermal therapy, bioimaging, in antibacterial agents and for the development of biosensors. Besides this, graphene has the scope to be used for wound healing, tissue engineering and regenerative medicine. In the present study, polyethylene-glycol-(PEG)ylated reduced graphene oxide (PrGO) was synthesized, characterized, and its interaction with mouse bone marrow mesenchymal stem cells (MSCs) was studied. in vitro cytotoxicity and differentiation study showed PrGO neither induced toxicity nor impaired the differentiation potential of the stem cells. PrGO was effectively internalized by MSCs and distributed throughout the cytoplasm. None of the PrGO was seen in the nucleus. Although it seems to induce increased reactive oxygen species (ROS) production inside the cell, no change in cell proliferation or cellular function was observed. Hence it is recommended that the synthesized PrGO is applicable for tissue engineering, and can also be used as a substrate platform for stem cell culture and differentiation.

Kv1.2 Channels at the Interface of Redox and Electrical Excitability

Kv1.2 is a prominent neuronal potassium channel subtype linked to severe epilepsies and movement disorders. We have demonstrated that neuronal and heterologously-expressed Kv1.2 channels exhibit use-dependent activation, a behavior characterized by progressive potentiation of channel activity during trains of repetitive stimuli. Use-dependent activation arises from a gating mode shift from a ‘reluctant’ slowly-activating mode to a ‘willing’ rapidly-activating mode with hyperpolarized voltage-dependence of activation. Moreover, Kv1.2 subunits recruit this use-dependent phenotype to heteromeric channel complexes. In this study, we demonstrate that use-dependent activation of Kv1.2 channel complexes is strongly regulated by a variety of exogenous and physiological redox species. Under ambient redox conditions, Kv1.2 channels exhibit marked cell-to-cell variability of use-dependent activation. However, exposure to mild reducing conditions normalizes this response, such that a pronounced use-dependent phenotype is consistently observed, together with a dramatic depolarizing shift of voltage-dependent activation with a V1/2 of 51+/- 6 mV. Mutagenesis of candidate cysteine residues in Kv1.2 did not affect redox sensitivity, therefore we hypothesize a role for an extrinsic redox-sensitive interacting partner. Using a variety of redox buffers, we demonstrate that use-dependent activation is steeply regulated by redox potentials between −50 and −100 mV, within the typical extracellular range. Furthermore, effects of membrane-impermeable reducing agents demonstrate that use-dependent activation is regulated by the extracellular redox state. Taken together, these findings suggest that Kv1.2 is a unique transducer of the extracellular environment, and may translate altered extracellular redox conditions to changes in cellular electrical function.

Skin aging and microRNAs

Skin aging, a manifestation of body senescence, is caused by changes of cellular structures and functions, as well as extracellular matrix (ECM) components in the epidermis and dermis. MicroRNAs (miRNAs), a kind of small non-coding endogenous RNA molecule, have been demonstrated to be related to senescence of the epidermis and dermis as well as ultraviolet (UV)-induced skin aging. In the dermis, miRNAs can affect the senescence of fibroblasts by targeting ECM components and cellular adhesion molecules, or by regulating cell cycle, telomerase activity, intracellular signaling pathways, oxidative stress, and so on. In the epidermis, miRNAs play a role in the senescence of keratinocytes through chromatin remodeling and the P63 pathway, and affect the senescence of Langerhans cells by targeting the transforming growth factor-β-dependent/independent pathway. In UV-induced skin aging, miRNAs participate in the process of skin aging via histone methylation, cell cycle regulators, transcriptional activitors, and so on. In addition, some miRNAs such as miR-125b participate in skin aging likely through epidermal stem cells. Key words: Skin aging; MicroRNAs; Dermis; Keratinocytes; Ultraviolet rays; Langerhans cells

PS 11-40 MENTHOL INHIBITS ENHANCED STORE-OPERATED CALCIUM ENTRY IN PLATELETS IS ASSOCIATED WITH PERIPHERAL ARTERY DISEASE FROM HYPERTENSION WITH TYPE 2 DIABETES

Objective: Menthol, a natural compound, is responsible for the minty flavor and smell of the mint plant and is widely used in food and drugs. A recent study showed that menthol modifies PLC signaling, which then leads to changes in cellular functions. Platelet dysfunction plays an important role in thrombosis in diabetes with peripheral artery disease (PAD). Store-operated calcium entry (SOCE) and stromal interaction molecule 1 (STIM1) regulate platelet activity by modulating calcium influx. We hypothesized that enhanced SOCE in platelets is associated with diabetes with PAD. Design and Method: We studied the activity of platelets from healthy participants (NT), type 2 diabetic patients (DM) and hypertension with type 2 diabetes (HDM). Platelet calcium influx and protein expression of STIM1 and sarcoendoplasmic reticulum Ca2+-ATPase 3 (SERCA3) were investigated. Results: Compared with that in platelets from DM, calcium influx was significantly increased in platelets from HDM in the absence of extracellular calcium after the discharge of intracellular Ca2+ stores by thapsigargin. Compared with platelets from DM without PAD, platelets from DM with PAD exhibited significantly increased SOCE. Menthol administration completely inhibited calcium influx in platelets from diabetic patients without PAD, but this effect was blunted in those from diabetic patients with PAD. Furthermore, the increased SOC calcium influx was correlated with the ankle brachial index (ABI) in diabetic patients. High glucose significantly up-regulated STIM1 and SERCA3 protein expression and induced the phosphorylation of phospholipase C (PLC) in platelets from healthy participants. This effect was attenuated in the presence of menthol or U73122, an inhibitor of PLC. Similarly, significant increases in STIM1 and SERCA3 protein expression were found in platelets from diabetic patients compared to those from healthy participants. Conclusions: Platelets from hypertension diabetic patients with PAD exhibited enhanced Store-operated calcium influx, which was associated with elevated STIM1/SERCA3 expression via a PLC-dependent pathway and was inhibited by menthol.

Critical importance of appropriate fixation conditions for faithful imaging of receptor microclusters.

ABSTRACTReceptor clustering is known to trigger signalling events that contribute to critical changes in cellular functions. Faithful imaging of such clusters by means of fluorescence microscopy relies on the application of adequate cell fixation methods prior to immunolabelling in order to avoid artefactual redistribution by the antibodies themselves. Previous work has highlighted the inadequacy of fixation with paraformaldehyde (PFA) alone for efficient immobilisation of membrane-associated molecules, and the advantages of fixation with PFA in combination with glutaraldehyde (GA). Using fluorescence microscopy, we here highlight how inadequate fixation can lead to the formation of artefactual clustering of receptors in lymphatic endothelial cells, focussing on the transmembrane hyaluronan receptors LYVE-1 and CD44, and the homotypic adhesion molecule CD31, each of which displays their native diffuse surface distribution pattern only when visualised with the right fixation techniques, i.e. PFA/GA in combination. Fluorescence recovery after photobleaching (FRAP) confirms that the artefactual receptor clusters are indeed introduced by residual mobility. In contrast, we observed full immobilisation of membrane proteins in cells that were fixed and then subsequently permeabilised, irrespective of whether the fixative was PFA or PFA/GA in combination. Our study underlines the importance of choosing appropriate sample preparation protocols for preserving authentic receptor organisation in advanced fluorescence microscopy.

Interaction of ARF-1.1 and neuronal calcium sensor-1 in the control of the temperature-dependency of locomotion in Caenorhabditis elegans.

Neuronal calcium sensor-1 (NCS-1) mediates changes in cellular function by regulating various target proteins. Many potential targets have been identified but the physiological significance of only a few has been established. Upon temperature elevation, Caenorhabditis elegans exhibits reversible paralysis. In the absence of NCS-1, worms show delayed onset and a shorter duration of paralysis. This phenotype can be rescued by re-expression of ncs-1 in AIY neurons. Mutants with defects in four potential NCS-1 targets (arf-1.1, pifk-1, trp-1 and trp-2) showed qualitatively similar phenotypes to ncs-1 null worms, although the effect of pifk-1 mutation on time to paralysis was considerably delayed. Inhibition of pifk-1 also resulted in a locomotion phenotype. Analysis of double mutants showed no additive effects between mutations in ncs-1 and trp-1 or trp-2. In contrast, double mutants of arf-1.1 and ncs-1 had an intermediate phenotype, consistent with NCS-1 and ARF-1.1 acting in the same pathway. Over-expression of arf-1.1 in the AIY neurons was sufficient to rescue partially the phenotype of both the arf-1.1 and the ncs-1 null worms. These findings suggest that ARF-1.1 interacts with NCS-1 in AIY neurons and potentially pifk-1 in the Ca2+ signaling pathway that leads to inhibited locomotion at an elevated temperature.

In Vitro Infection with Dengue Virus Induces Changes in the Structure and Function of the Mouse Brain Endothelium.

BackgroundThe neurological manifestations of dengue disease are occurring with greater frequency, and currently, no information is available regarding the reasons for this phenomenon. Some viruses infect and/or alter the function of endothelial organs, which results in changes in cellular function, including permeability of the blood-brain barrier (BBB), which allows the entry of infected cells or free viral particles into the nervous system.MethodsIn the present study, we standardized two in vitro models, a polarized monolayer of mouse brain endothelial cells (MBECs) and an organized co-culture containing MBECs and astrocytes. Using these cell models, we assessed whether DENV-4 or the neuro-adapted dengue virus (D4MB-6) variant infects cells or induces changes in the structure or function of the endothelial barrier.ResultsThe results showed that MBECs, but not astrocytes, were susceptible to infection with both viruses, although the percentage of infected cells was higher when the neuro-adapted virus variant was used. In both culture systems, DENV infection changed the localization of the tight junction proteins Zonula occludens (ZO-1) and Claudin-1 (Cln1), and this process was associated with a decrease in transendothelial resistance, an increase in macromolecule permeability and an increase in the paracellular passing of free virus particles. MBEC infection led to transcriptional up-regulation of adhesion molecules (VCAM-1 and PECAM) and immune mediators (MCP-1 and TNF- α) that are associated with immune cell transmigration, mainly in D4MB-6-infected cells.ConclusionThese results indicate that DENV infection in MBECs altered the structure and function of the BBB and activated the endothelium, affecting its transcellular and paracellular permeability and favoring the passage of viruses and the transmigration of immune cells. This phenomenon can be harnessed for neurotropic and neurovirulent strains to infect and induce alterations in the CNS.

Connecting common genetic polymorphisms to protein function: A modular project sequence for lecture or lab

Single nucleotide polymorphisms (SNPs) in DNA can result in phenotypes where the biochemical basis may not be clear due to the lack of protein structures. With the growing number of modeling and simulation software available on the internet, students can now participate in determining how small changes in genetic information impact cellular protein structure and function. We have developed a modular series of activities to engage lab or lecture students in examining the basis for common phenotypes. The activities range from basic phenotype testing/observation to DNA sequencing and simulation of protein structure and dynamics. We provide as an example study of the bitterness receptor TAS2R38 and PTC tasting, however these activities are applicable to other SNPs or genomic variants with a direct connection to an observable phenotype. These activities are modular and can be mixed to meet the student capabilities and infrastructure availability. The complete sequence of activities will demonstrate the direct connection between gene structure, protein structure and organism function. © 2016 by The International Union of Biochemistry and Molecular Biology, 44(6):526-536, 2016.

Metabolic regulation of immune responses: therapeutic opportunities.

Immune cell metabolism is dynamically regulated in parallel with the substantial changes in cellular function that accompany immune cell activation. While these changes in metabolism are important for facilitating the increased energetic and biosynthetic demands of activated cells, immune cell metabolism also has direct roles in controlling the functions of immune cells and shaping the immune response. A theme is emerging wherein nutrients, metabolic enzymes, and metabolites can act as an extension of the established immune signal transduction pathways, thereby adding an extra layer of complexity to the regulation of immunity. This Review will outline the metabolic configurations adopted by different immune cell subsets, describe the emerging roles for metabolic enzymes and metabolites in the control of immune cell function, and discuss the therapeutic implications of this emerging immune regulatory axis.

Molecular Mechanisms of Pulmonary Vascular Remodeling in Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is a devastating disease that is precipitated by hypertrophic pulmonary vascular remodeling of distal arterioles to increase pulmonary artery pressure and pulmonary vascular resistance in the absence of left heart, lung parenchymal, or thromboembolic disease. Despite available medical therapy, pulmonary artery remodeling and its attendant hemodynamic consequences result in right ventricular dysfunction, failure, and early death. To limit morbidity and mortality, attention has focused on identifying the cellular and molecular mechanisms underlying aberrant pulmonary artery remodeling to identify pathways for intervention. While there is a well-recognized heritable genetic component to PAH, there is also evidence of other genetic perturbations, including pulmonary vascular cell DNA damage, activation of the DNA damage response, and variations in microRNA expression. These findings likely contribute, in part, to dysregulation of proliferation and apoptosis signaling pathways akin to what is observed in cancer; changes in cellular metabolism, metabolic flux, and mitochondrial function; and endothelial-to-mesenchymal transition as key signaling pathways that promote pulmonary vascular remodeling. This review will highlight recent advances in the field with an emphasis on the aforementioned molecular mechanisms as contributors to the pulmonary vascular disease pathophenotype.

Endotoxin Disrupts Circadian Rhythms in Macrophages via Reactive Oxygen Species.

The circadian clock is a transcriptional network that functions to regulate the expression of genes important in the anticipation of changes in cellular and organ function. Recent studies have revealed that the recognition of pathogens and subsequent initiation of inflammatory responses are strongly regulated by a macrophage-intrinsic circadian clock. We hypothesized that the circadian pattern of gene expression might be influenced by inflammatory stimuli and that loss of circadian function in immune cells can promote pro-inflammatory behavior. To investigate circadian rhythms in inflammatory cells, peritoneal macrophages were isolated from mPer2luciferase transgenic mice and circadian oscillations were studied in response to stimuli. Using Cosinor analysis, we found that LPS significantly altered the circadian period in peritoneal macrophages from mPer2luciferase mice while qPCR data suggested that the pattern of expression of the core circadian gene (Bmal1) was disrupted. Inhibition of TLR4 offered protection from the LPS-induced impairment in rhythm, suggesting a role for toll-like receptor signaling. To explore the mechanisms involved, we inhibited LPS-stimulated NO and superoxide. Inhibition of NO synthesis with L-NAME had no effect on circadian rhythms. In contrast, inhibition of superoxide with Tempol or PEG-SOD ameliorated the LPS-induced changes in circadian periodicity. In gain of function experiments, we found that overexpression of NOX5, a source of ROS, could significantly disrupt circadian function in a circadian reporter cell line (U2OS) whereas iNOS overexpression, a source of NO, was ineffective. To assess whether alteration of circadian rhythms influences macrophage function, peritoneal macrophages were isolated from Bmal1-KO and Per-TKO mice. Compared to WT macrophages, macrophages from circadian knockout mice exhibited altered balance between NO and ROS release, increased uptake of oxLDL and increased adhesion and migration. These results suggest that pro-inflammatory stimuli can disrupt circadian rhythms in macrophages and that impaired circadian rhythms may contribute to cardiovascular diseases by altering macrophage behavior.

Impact of the Type I Interferon Receptor on the Global Gene Expression Program During the Course of Dendritic Cell Maturation Induced by Polyinosinic Polycytidylic Acid

Dendritic cell (DC) maturation involves widespread changes in cellular function and gene expression. The regulatory role of IFNAR in the program of DC maturation remains incompletely defined. Thus, the time evolution impact of IFNAR on this process was evaluated. Changes in DC phenotype, function, and gene expression induced by poly I:C were measured in wild-type and IFNAR(-/-) DC at 9 time points over 24 h. Temporal gene expression profiles were filtered on consistency and response magnitude across replicates. The number of genes whose expression was altered by poly I:C treatment was greatly reduced in IFNAR(-/-) DC, including the majority of the downregulated gene expression program previously observed in wild-type (WT) DC. Furthermore, the number of genes upregulated was almost equal between WT and IFNAR(-/-) DC, yet the identities of those genes were distinct. Integrating these data with protein-protein interaction data revealed several novel subnetworks active during maturation, including nucleotide synthesis, metabolism, and repair. A subnetwork associated with redox activity was uniquely identified in IFNAR(-/-) DC. Overall, temporal gene expression and network analyses identified many genes regulated by the type I interferon response and revealed previously unidentified aspects of the DC maturation process.

Innate immune reconstitution with suppression of HIV-1.

Progressive HIV-1 infection leads to both profound immune suppression and pathologic inflammation in the majority of infected individuals. While adaptive immune dysfunction, as evidenced by CD4+ T cell depletion and exhaustion, has been extensively studied, less is known about the functional capacity of innate immune cell populations in the context of HIV-1 infection. Given the broad susceptibility to opportunistic infections and the dysregulated inflammation observed in progressive disease, we hypothesized that there would be significant changes in the innate cellular responses. Using a cohort of patients with multiple samplings before and after antiretroviral therapy (ART) initiation, we demonstrated increased responses to innate immune stimuli following viral suppression, as measured by the production of inflammatory cytokines. Plasma viral load itself had the strongest association with this change in innate functional capacity. We further identified epigenetic modifications in the TNFA promoter locus in monocytes that are associated with viremia, suggesting a molecular mechanism for the observed changes in innate immune function following initiation of ART. These data indicate that suppression of HIV-1 viremia is associated with changes in innate cellular function that may in part determine the restoration of protective immune responses.

Chronic stress induces persistent changes in global DNA methylation and gene expression in the medial prefrontal cortex, orbitofrontal cortex, and hippocampus

Chronic stress is associated with a plethora of cognitive symptoms such as emotional dysregulation and impaired executive function that have been attributed to modifications in neuroanatomy in the orbitofrontal cortex (OFC), medial prefrontal cortex (mPFC), and hippocampus (HPC). While many studies have examined stress-induced changes in neuronal morphology, synaptic plasticity, and cellular function, there has been little investigation into persistent changes in gene expression that may be responsible for the maintenance of these changes. This study exposed adult rats to a chronic stressor and then examined changes in mRNA gene expression in the OFC, mPFC and HPC following a two-week withdrawal period. mRNA bio-sequencing results revealed sex- and region-dependent changes. Surprisingly the greatest changes in gene expression were found in the OFC, and similar to anatomical studies, analysis of gene changes with Ingenuity Pathway Analysis software demonstrated that the mPFC and OFC exhibited contrasting activation of canonical pathways and functional networks. The HPC demonstrated the largest degree of sex-dependent change in gene expression. In general, chronic stress induced persistent changes in gene expression in the three brain regions we examined and these changes could be associated with the commonly reported cognitive symptoms. The current study highlights the region- and sex-dependent nature of the brain’s response to chronic stress and the difficulty we face when attempting to develop treatment options.