scholarly journals Phospholipid Composition of APOE Lipoproteins Affects Microglia Activation in an Isoform-specific Manner

2020 ◽  
Author(s):  
Nicholas Fitz ◽  
KyongNyon Nam ◽  
Cody Wolfe ◽  
Florent Letronne ◽  
Brittany Playso ◽  
...  
Keyword(s):  
Phospholipid Composition ◽  
Time Lapse ◽  
Postmortem Brain ◽  
Two Photon ◽  
Activated State ◽  
Microglial Migration ◽  
Human Apoe3 ◽  
High Level ◽  
Microglial Response

Abstract Apolipoprotein E4 (APOE) is the strongest genetic risk factor for Alzheimer’s disease (AD). Our lipidomic analysis identified a common phospholipid signature with a high level of correlation between APOEε3/3 and APOEε4/4 AD postmortem brain samples and native lipoproteins isolated from astrocyte conditioned media of mice expressing human APOE3 or APOE4. Behavioral testing demonstrated that native E3 lipoproteins were more effective than E4 at ameliorating the harmful effects of Aβ on cognition. We posit that APOE isoform-specific differences in the phospholipid composition of native lipoproteins prompt a differential microglial response. Using time-lapse in vivo two-photon imaging we compared the effect of E3 or E4 infused with Aβ and determined that E3 lipoproteins induced a faster microglial migration towards Aβ. To determine how E3 and E4 lipoproteins affect microglial transcriptome in response to Aβ we performed bulk and single cell RNA-seq of WT and Trem2ko mice. We show that compared to E4, cortical infusion of E3 lipoproteins upregulated a higher proportion of genes associated with an activated immune response accompanied by a downregulation of homeostatic genes. scRNA-seq identified microglia-specific clusters affected by Trem2 deficiency suggesting that lack of Trem2 impairs the transition of microglia from homeostatic to an activated state. Compared to E3, E4-expressing microglia showed a reduced Aβ uptake that was additionally aggravated by Trem2 deficiency. Together, our findings have elucidated unique phenotypic and transcriptional differences in the microglial response to Aβ in the presence of E3 or E4 lipoproteins which could impact AD pathogenesis.

scholarly journals Conditioning sharpens the spatial representation of rewarded stimuli in mouse primary visual cortex

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Pieter M Goltstein ◽  
Guido T Meijer ◽  
Cyriel MA Pennartz
Keyword(s):  
Visual Space ◽  
Spatial Separation ◽  
Time Lapse ◽  
Optical Signal ◽  
Population Coding ◽  
Cortical Representation ◽  
Population Activity ◽  
Two Photon ◽  
Structure Of Population

Reward is often employed as reinforcement in behavioral paradigms but it is unclear how the visuospatial aspect of a stimulus-reward association affects the cortical representation of visual space. Using a head-fixed paradigm, we conditioned mice to associate the same visual pattern in adjacent retinotopic regions with availability and absence of reward. Time-lapse intrinsic optical signal imaging under anesthesia showed that conditioning increased the spatial separation of mesoscale cortical representations of reward predicting- and non-reward predicting stimuli. Subsequent in vivo two-photon calcium imaging revealed that this improved separation correlated with enhanced population coding for retinotopic location, specifically for the trained orientation and spatially confined to the V1 region where rewarded and non-rewarded stimulus representations bordered. These results are corroborated by conditioning-induced differences in the correlation structure of population activity. Thus, the cortical representation of visual space is sharpened as consequence of associative stimulus-reward learning while the overall retinotopic map remains unaltered.

scholarly journals Protocadherin-19 and N-cadherin interact to control cell movements during anterior neurulation

2010 ◽  
Vol 191 (5) ◽  
pp. 1029-1041 ◽  
Author(s):  
Sayantanee Biswas ◽  
Michelle R. Emond ◽  
James D. Jontes
Keyword(s):  
Cell Adhesion ◽  
Control Cell ◽  
Time Lapse ◽  
Image Sequences ◽  
Cell Movements ◽  
Calcium Dependent ◽  
Two Photon ◽  
Cadherin Superfamily

The protocadherins comprise the largest subgroup within the cadherin superfamily, yet their cellular and developmental functions are not well understood. In this study, we demonstrate that pcdh19 (protocadherin 19) acts synergistically with n-cadherin (ncad) during anterior neurulation in zebrafish. In addition, Pcdh19 and Ncad interact directly, forming a protein–protein complex both in vitro and in vivo. Although both molecules are required for calcium-dependent adhesion in a zebrafish cell line, the extracellular domain of Pcdh19 does not exhibit adhesive activity, suggesting that the involvement of Pcdh19 in cell adhesion is indirect. Quantitative analysis of in vivo two-photon time-lapse image sequences reveals that loss of either pcdh19 or ncad impairs cell movements during neurulation, disrupting both the directedness of cell movements and the coherence of movements among neighboring cells. Our results suggest that Pcdh19 and Ncad function together to regulate cell adhesion and to mediate morphogenetic movements during brain development.

scholarly journals Oxysterols and EBI2 promote osteoclast precursor migration to bone surfaces and regulate bone mass homeostasis

2015 ◽  
Vol 212 (11) ◽  
pp. 1931-1946 ◽  
Author(s):  
Erin Nevius ◽  
Flavia Pinho ◽  
Meera Dhodapkar ◽  
Huiyan Jin ◽  
Kristina Nadrah ◽  
...  
Keyword(s):  
Bone Mass ◽  
Therapeutic Potential ◽  
Time Lapse ◽  
Two Photon Microscopy ◽  
Two Photon ◽  
Time Lapse Microscopy ◽  
Necessary And Sufficient ◽  
Gαi Protein

Bone surfaces attract hematopoietic and nonhematopoietic cells, such as osteoclasts (OCs) and osteoblasts (OBs), and are targeted by bone metastatic cancers. However, the mechanisms guiding cells toward bone surfaces are essentially unknown. Here, we show that the Gαi protein–coupled receptor (GPCR) EBI2 is expressed in mouse monocyte/OC precursors (OCPs) and its oxysterol ligand 7α,25-dihydroxycholesterol (7α,25-OHC) is secreted abundantly by OBs. Using in vitro time-lapse microscopy and intravital two-photon microscopy, we show that EBI2 enhances the development of large OCs by promoting OCP motility, thus facilitating cell–cell interactions and fusion in vitro and in vivo. EBI2 is also necessary and sufficient for guiding OCPs toward bone surfaces. Interestingly, OCPs also secrete 7α,25-OHC, which promotes autocrine EBI2 signaling and reduces OCP migration toward bone surfaces in vivo. Defective EBI2 signaling led to increased bone mass in male mice and protected female mice from age- and estrogen deficiency–induced osteoporosis. This study identifies a novel pathway involved in OCP homing to the bone surface that may have significant therapeutic potential.

CMT disease 2A and demyelination decouple ATP and ROS production by axonal mitochondria

2018 ◽  
Author(s):  
Gerben van Hameren ◽  
Graham Campbell ◽  
Marie Deck ◽  
Jade Berthelot ◽  
Roman Chrast ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Time Lapse ◽  
Ros Production ◽  
Oxygen Species ◽  
Myelinated Axons ◽  
Charcot Marie Tooth ◽  
Atp Production ◽  
Two Photon ◽  
Demyelinating Peripheral Neuropathy

AbstractMitochondria are critical for the function and maintenance of myelinated axons notably through ATP production. A by-product of this activity is reactive oxygen species (ROS), which are highly deleterious for neurons. While ROS and metabolism are involved in several neurodegenerative diseases, it is still unclear how axonal activity or myelin modulates ATP and ROS production in axonal mitochondria. We imaged and quantified mitochondrial ATP and hydrogen peroxide (H2O2) in resting or stimulated peripheral nerve myelinated axons in vivo, using genetically-encoded fluorescent probes, two-photon time-lapse and CARS imaging. ATP and H2O2 productions are intrinsically higher in nodes of Ranvier even in resting conditions. Axonal firing increased both ATP and H2O2 productions but with different dynamics. In neuropathic MFN2R94Q mice, mimicking Charcot-Marie-Tooth 2A disease, defective mitochondria failed to upregulate ATP production following axonal activity. However, H2O2 production was dramatically sustained. Mimicking demyelinating peripheral neuropathy resulted in a reduced production of ATP while H2O2 level soared. Taken together, our results suggest that ATP and ROS productions are decoupled under neuropathic conditions, which may compromise axonal function and integrity.

scholarly journals Remyelination alters the pattern of myelin in the cerebral cortex

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Jennifer Orthmann-Murphy ◽  
Cody L Call ◽  
Gian C Molina-Castro ◽  
Yu Chen Hsieh ◽  
Matthew N Rasband ◽  
...  
Keyword(s):  
Time Lapse ◽  
Cognitive Disability ◽  
Cortical Circuits ◽  
Cortical Layers ◽  
Two Photon ◽  
Myelin Sheaths ◽  
Adult Mice ◽  
Cortical Gray Matter ◽  
Circuit Function

Destruction of oligodendrocytes and myelin sheaths in cortical gray matter profoundly alters neural activity and is associated with cognitive disability in multiple sclerosis (MS). Myelin can be restored by regenerating oligodendrocytes from resident progenitors; however, it is not known whether regeneration restores the complex myelination patterns in cortical circuits. Here, we performed time lapse in vivo two photon imaging in somatosensory cortex of adult mice to define the kinetics and specificity of myelin regeneration after acute oligodendrocyte ablation. These longitudinal studies revealed that the pattern of myelination in cortex changed dramatically after regeneration, as new oligodendrocytes were formed in different locations and new sheaths were often established along axon segments previously lacking myelin. Despite the dramatic increase in axonal territory available, oligodendrogenesis was persistently impaired in deeper cortical layers that experienced higher gliosis. Repeated reorganization of myelin patterns in MS may alter circuit function and contribute to cognitive decline.

scholarly journals Remyelination alters the pattern of myelin in the cerebral cortex

2020 ◽  
Author(s):  
Jennifer Orthmann-Murphy ◽  
Cody L. Call ◽  
Gian Carlo Molina-Castro ◽  
Yu Chen Hsieh ◽  
Matthew N. Rasband ◽  
...  
Keyword(s):  
Time Lapse ◽  
Cognitive Disability ◽  
Cortical Circuits ◽  
Cortical Layers ◽  
Two Photon ◽  
Myelin Sheaths ◽  
Adult Mice ◽  
Cortical Gray Matter ◽  
Circuit Function

ABSTRACTDestruction of oligodendrocytes and myelin sheaths in cortical gray matter profoundly alters neural activity and is associated with cognitive disability in multiple sclerosis (MS). Myelin can be restored by regenerating oligodendrocytes from resident progenitors; however, it is not known whether regeneration restores the complex myelination patterns in cortical circuits. Here we performed time lapse in vivo two photon imaging in somatosensory cortex of adult mice to define the kinetics and specificity of myelin regeneration after acute oligodendrocyte ablation. These longitudinal studies revealed that the pattern of myelination in cortex changed dramatically after regeneration, as new oligodendrocytes were formed in different locations and new sheaths were often established along axon segments previously lacking myelin. Despite the dramatic increase in axonal territory available, oligodendrogenesis was persistently impaired in deeper cortical layers that experienced higher gliosis. The repeated reorganization of myelin patterns in MS may alter circuit function and contribute to cognitive decline.

Ultrastructure of melanocyte-keratinocyte interactions and pigment transfer in vitro

1978 ◽  
Vol 36 (2) ◽  
pp. 650-651
Author(s):  
Raul I. Garcia ◽  
Evelyn A. Flynn ◽  
George Szabo
Keyword(s):  
Direct Injection ◽  
Skin Pigmentation ◽  
Freeze Fracture ◽  
Pigment Granule ◽  
Time Lapse ◽  
Ultrastructural Level ◽  
Lanthanum Tracer ◽  
A Cell

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

In vivo imaging of liver injury and regeneration by functional two-photon microscopy

2016 ◽  
Vol 54 (12) ◽  
pp. 1343-1404
Author(s):  
A Ghallab ◽  
R Reif ◽  
R Hassan ◽  
AS Seddek ◽  
JG Hengstler
Keyword(s):  
Liver Injury ◽  
In Vivo Imaging ◽  
Two Photon Microscopy ◽  
Two Photon

scholarly journals High-speed volumetric two-photon fluorescence imaging of neurovascular dynamics

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiang Lan Fan ◽  
Jose A. Rivera ◽  
Wei Sun ◽  
John Peterson ◽  
Henry Haeberle ◽  
...  
Keyword(s):  
Blood Flow ◽  
High Speed ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Laser Scanning Microscopy ◽  
Fluorescence Signal ◽  
Imaging Method ◽  
Spatiotemporal Resolution ◽  
Two Photon

AbstractUnderstanding the structure and function of vasculature in the brain requires us to monitor distributed hemodynamics at high spatial and temporal resolution in three-dimensional (3D) volumes in vivo. Currently, a volumetric vasculature imaging method with sub-capillary spatial resolution and blood flow-resolving speed is lacking. Here, using two-photon laser scanning microscopy (TPLSM) with an axially extended Bessel focus, we capture volumetric hemodynamics in the awake mouse brain at a spatiotemporal resolution sufficient for measuring capillary size and blood flow. With Bessel TPLSM, the fluorescence signal of a vessel becomes proportional to its size, which enables convenient intensity-based analysis of vessel dilation and constriction dynamics in large volumes. We observe entrainment of vasodilation and vasoconstriction with pupil diameter and measure 3D blood flow at 99 volumes/second. Demonstrating high-throughput monitoring of hemodynamics in the awake brain, we expect Bessel TPLSM to make broad impacts on neurovasculature research.

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