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Xu J, Sun X, Chen Z, Ma H, Liu Y. Super-resolution imaging of T lymphocyte activation reveals chromatin decondensation and disrupted nuclear envelope. Commun Biol 2024; 7:717. [PMID: 38858440 PMCID: PMC11164909 DOI: 10.1038/s42003-024-06393-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 05/23/2024] [Indexed: 06/12/2024] Open
Abstract
T lymphocyte activation plays a pivotal role in adaptive immune response and alters the spatial organization of nuclear architecture that subsequently impacts transcription activities. Here, using stochastic optical reconstruction microscopy (STORM), we observe dramatic de-condensation of chromatin and the disruption of nuclear envelope at a nanoscale resolution upon T lymphocyte activation. Super-resolution imaging reveals that such alterations in nuclear architecture are accompanied by the release of nuclear DNA into the cytoplasm, correlating with the degree of chromatin decompaction within the nucleus. The authors show that under the influence of metabolism, T lymphocyte activation de-condenses chromatin, disrupts the nuclear envelope, and releases DNA into the cytoplasm. Taken together, this result provides a direct, molecular-scale insight into the alteration in nuclear architecture. It suggests the release of nuclear DNA into the cytoplasm as a general consequence of chromatin decompaction after lymphocyte activation.
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Affiliation(s)
- Jianquan Xu
- Biomedical Optical Imaging Laboratory, Departments of Medicine and Bioengineering, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Xuejiao Sun
- Biomedical Optical Imaging Laboratory, Departments of Medicine and Bioengineering, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Zhangguo Chen
- UPMC Hillman Cancer Center, Division of Hematology and Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Hongqiang Ma
- Biomedical Optical Imaging Laboratory, Departments of Medicine and Bioengineering, University of Pittsburgh, Pittsburgh, PA, 15213, USA
- Department of Bioengineering, Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Yang Liu
- Biomedical Optical Imaging Laboratory, Departments of Medicine and Bioengineering, University of Pittsburgh, Pittsburgh, PA, 15213, USA.
- Department of Bioengineering, Department of Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology, Cancer Center at Illinois, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA.
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Li Y, Bertozzi A, Mann MRW, Kühn B. Interdependent changes of nuclear lamins, nuclear pore complexes, and ploidy regulate cellular regeneration and stress response in the heart. Nucleus 2023; 14:2246310. [PMID: 37606283 PMCID: PMC10446781 DOI: 10.1080/19491034.2023.2246310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 07/28/2023] [Accepted: 08/04/2023] [Indexed: 08/23/2023] Open
Abstract
In adult mammals, many heart muscle cells (cardiomyocytes) are polyploid, do not proliferate (post-mitotic), and, consequently, cannot contribute to heart regeneration. In contrast, fetal and neonatal heart muscle cells are diploid, proliferate, and contribute to heart regeneration. We have identified interdependent changes of the nuclear lamina, nuclear pore complexes, and DNA-content (ploidy) in heart muscle cell maturation. These results offer new perspectives on how cells alter their nuclear transport and, with that, their gene regulation in response to extracellular signals. We present how changes of the nuclear lamina alter nuclear pore complexes in heart muscle cells. The consequences of these changes for cellular regeneration and stress response in the heart are discussed.
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Affiliation(s)
- Yao Li
- Division of Pediatric Cardiology, Pediatric Institute for Heart Regeneration and Therapeutics (I-HRT), UPMC Children’s Hospital of Pittsburgh, Pittsburgh, PA, USA
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Alberto Bertozzi
- Division of Pediatric Cardiology, Pediatric Institute for Heart Regeneration and Therapeutics (I-HRT), UPMC Children’s Hospital of Pittsburgh, Pittsburgh, PA, USA
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Mellissa RW Mann
- Department of Obstetrics, Gynaecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Magee-Womens Research Institute, Pittsburgh, PA, USA
| | - Bernhard Kühn
- Division of Pediatric Cardiology, Pediatric Institute for Heart Regeneration and Therapeutics (I-HRT), UPMC Children’s Hospital of Pittsburgh, Pittsburgh, PA, USA
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- McGowan Institute of Regenerative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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3
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Malik SC, Lin JD, Ziegler-Waldkirch S, Tholen S, Deshpande SS, Schwabenland M, Schilling O, Vlachos A, Meyer-Luehmann M, Schachtrup C. Tpr Misregulation in Hippocampal Neural Stem Cells in Mouse Models of Alzheimer's Disease. Cells 2023; 12:2757. [PMID: 38067185 PMCID: PMC10706632 DOI: 10.3390/cells12232757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 11/19/2023] [Accepted: 11/29/2023] [Indexed: 12/18/2023] Open
Abstract
Nuclear pore complexes (NPCs) are highly dynamic macromolecular protein structures that facilitate molecular exchange across the nuclear envelope. Aberrant NPC functioning has been implicated in neurodegeneration. The translocated promoter region (Tpr) is a critical scaffolding nucleoporin (Nup) of the nuclear basket, facing the interior of the NPC. However, the role of Tpr in adult neural stem/precursor cells (NSPCs) in Alzheimer's disease (AD) is unknown. Using super-resolution (SR) and electron microscopy, we defined the different subcellular localizations of Tpr and phospho-Tpr (P-Tpr) in NSPCs in vitro and in vivo. Elevated Tpr expression and reduced P-Tpr nuclear localization accompany NSPC differentiation along the neurogenic lineage. In 5xFAD mice, an animal model of AD, increased Tpr expression in DCX+ hippocampal neuroblasts precedes increased neurogenesis at an early stage, before the onset of amyloid-β plaque formation. Whereas nuclear basket Tpr interacts with chromatin modifiers and NSPC-related transcription factors, P-Tpr interacts and co-localizes with cyclin-dependent kinase 1 (Cdk1) at the nuclear chromatin of NSPCs. In hippocampal NSPCs in a mouse model of AD, aberrant Tpr expression was correlated with altered NPC morphology and counts, and Tpr was aberrantly expressed in postmortem human brain samples from patients with AD. Thus, we propose that altered levels and subcellular localization of Tpr in CNS disease affect Tpr functionality, which in turn regulates the architecture and number of NSPC NPCs, possibly leading to aberrant neurogenesis.
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Affiliation(s)
- Subash C. Malik
- Institute of Anatomy and Cell Biology, University of Freiburg, 79104 Freiburg, Germany; (S.C.M.); (J.-D.L.); (S.S.D.)
- Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Jia-Di Lin
- Institute of Anatomy and Cell Biology, University of Freiburg, 79104 Freiburg, Germany; (S.C.M.); (J.-D.L.); (S.S.D.)
- Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Stephanie Ziegler-Waldkirch
- Department of Neurology, Medical Center, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany; (S.Z.-W.); (M.M.-L.)
| | - Stefan Tholen
- Institute of Surgical Pathology, Medical Center, University of Freiburg, 79106 Freiburg, Germany; (S.T.); (O.S.)
| | - Sachin S. Deshpande
- Institute of Anatomy and Cell Biology, University of Freiburg, 79104 Freiburg, Germany; (S.C.M.); (J.-D.L.); (S.S.D.)
- Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Marius Schwabenland
- Institute of Neuropathology, University of Freiburg, 79106 Freiburg, Germany
| | - Oliver Schilling
- Institute of Surgical Pathology, Medical Center, University of Freiburg, 79106 Freiburg, Germany; (S.T.); (O.S.)
| | - Andreas Vlachos
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany;
- Center BrainLinks-BrainTools, University of Freiburg, 79110 Freiburg, Germany
- Center for Basics in Neuromodulation (NeuroModul Basics), Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
| | - Melanie Meyer-Luehmann
- Department of Neurology, Medical Center, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany; (S.Z.-W.); (M.M.-L.)
- Center for Basics in Neuromodulation (NeuroModul Basics), Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
| | - Christian Schachtrup
- Institute of Anatomy and Cell Biology, University of Freiburg, 79104 Freiburg, Germany; (S.C.M.); (J.-D.L.); (S.S.D.)
- Center for Basics in Neuromodulation (NeuroModul Basics), Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
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West G, Sedighi S, Agnetti G, Taimen P. Intermediate filaments in the heart: The dynamic duo of desmin and lamins orchestrates mechanical force transmission. Curr Opin Cell Biol 2023; 85:102280. [PMID: 37972529 DOI: 10.1016/j.ceb.2023.102280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/05/2023] [Accepted: 10/25/2023] [Indexed: 11/19/2023]
Abstract
The intermediate filament (IF) cytoskeleton supports cellular structural integrity, particularly in response to mechanical stress. The most abundant IF proteins in mature cardiomyocytes are desmin and lamins. The desmin network tethers the contractile apparatus and organelles to the nuclear envelope and the sarcolemma, while lamins, as components of the nuclear lamina, provide structural stability to the nucleus and the genome. Mutations in desmin or A-type lamins typically result in cardiomyopathies and recent studies emphasized the synergistic roles of desmin and lamins in the maintenance of nuclear integrity in cardiac myocytes. Here we explore the emerging roles of the interdependent relationship between desmin and lamins in providing resilience to nuclear structure while transducing extracellular mechanical cues into the nucleus.
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Affiliation(s)
- Gun West
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520, Turku, Finland
| | - Sogol Sedighi
- Johns Hopkins University School of Medicine, 21205, Baltimore, MD, USA
| | - Giulio Agnetti
- Johns Hopkins University School of Medicine, 21205, Baltimore, MD, USA; DIBINEM - University of Bologna, 40123, Bologna, Italy.
| | - Pekka Taimen
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520, Turku, Finland; Department of Pathology, Turku University Hospital, 20520, Turku, Finland.
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Mich-Basso JD, Kühn B. Protocol to image and quantify nuclear pore complexes using high-resolution laser scanning confocal microscopy. STAR Protoc 2023; 4:102552. [PMID: 37651236 PMCID: PMC10495640 DOI: 10.1016/j.xpro.2023.102552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 06/13/2023] [Accepted: 08/10/2023] [Indexed: 09/02/2023] Open
Abstract
Nuclear pore complexes are pathways for nuclear-cytoplasmic communication that participate in chromatin organization. Here, we present a protocol to image and quantify the number of nuclear pore complexes in cells. We describe steps for cell plating and culture, immunofluorescence detection, and confocal microscopy visualization of nuclear pore complexes. We then detail quantification and 3D data analysis. This protocol utilizes digital thresholding under human supervision for quantification of nuclear pore complexes. For complete details on the use and execution of this protocol, please refer to Han et al.1.
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Affiliation(s)
- Jocelyn D Mich-Basso
- Division of Cardiology, Pediatric Institute for Heart Regeneration and Therapeutics (I-HRT), UPMC Children's Hospital of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA 15224, USA; Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
| | - Bernhard Kühn
- Division of Cardiology, Pediatric Institute for Heart Regeneration and Therapeutics (I-HRT), UPMC Children's Hospital of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA 15224, USA; Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA.
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Guo QY, Yang JQ, Feng XX, Zhou YJ. Regeneration of the heart: from molecular mechanisms to clinical therapeutics. Mil Med Res 2023; 10:18. [PMID: 37098604 PMCID: PMC10131330 DOI: 10.1186/s40779-023-00452-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 03/22/2023] [Indexed: 04/27/2023] Open
Abstract
Heart injury such as myocardial infarction leads to cardiomyocyte loss, fibrotic tissue deposition, and scar formation. These changes reduce cardiac contractility, resulting in heart failure, which causes a huge public health burden. Military personnel, compared with civilians, is exposed to more stress, a risk factor for heart diseases, making cardiovascular health management and treatment innovation an important topic for military medicine. So far, medical intervention can slow down cardiovascular disease progression, but not yet induce heart regeneration. In the past decades, studies have focused on mechanisms underlying the regenerative capability of the heart and applicable approaches to reverse heart injury. Insights have emerged from studies in animal models and early clinical trials. Clinical interventions show the potential to reduce scar formation and enhance cardiomyocyte proliferation that counteracts the pathogenesis of heart disease. In this review, we discuss the signaling events controlling the regeneration of heart tissue and summarize current therapeutic approaches to promote heart regeneration after injury.
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Affiliation(s)
- Qian-Yun Guo
- Beijing Key Laboratory of Precision Medicine of Coronary Atherosclerotic Disease, Beijing Institute of Heart Lung and Blood Vessel Disease, Clinical Center for Coronary Heart Disease, Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, 100029, China
| | - Jia-Qi Yang
- Beijing Key Laboratory of Precision Medicine of Coronary Atherosclerotic Disease, Beijing Institute of Heart Lung and Blood Vessel Disease, Clinical Center for Coronary Heart Disease, Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, 100029, China
| | - Xun-Xun Feng
- Beijing Key Laboratory of Precision Medicine of Coronary Atherosclerotic Disease, Beijing Institute of Heart Lung and Blood Vessel Disease, Clinical Center for Coronary Heart Disease, Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, 100029, China
| | - Yu-Jie Zhou
- Beijing Key Laboratory of Precision Medicine of Coronary Atherosclerotic Disease, Beijing Institute of Heart Lung and Blood Vessel Disease, Clinical Center for Coronary Heart Disease, Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, 100029, China.
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Walker SG, Langland CJ, Viles J, Hecker LA, Wallrath LL. Drosophila Models Reveal Properties of Mutant Lamins That Give Rise to Distinct Diseases. Cells 2023; 12:cells12081142. [PMID: 37190051 DOI: 10.3390/cells12081142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 04/06/2023] [Accepted: 04/06/2023] [Indexed: 05/17/2023] Open
Abstract
Mutations in the LMNA gene cause a collection of diseases known as laminopathies, including muscular dystrophies, lipodystrophies, and early-onset aging syndromes. The LMNA gene encodes A-type lamins, lamins A/C, intermediate filaments that form a meshwork underlying the inner nuclear membrane. Lamins have a conserved domain structure consisting of a head, coiled-coil rod, and C-terminal tail domain possessing an Ig-like fold. This study identified differences between two mutant lamins that cause distinct clinical diseases. One of the LMNA mutations encodes lamin A/C p.R527P and the other codes lamin A/C p.R482W, which are typically associated with muscular dystrophy and lipodystrophy, respectively. To determine how these mutations differentially affect muscle, we generated the equivalent mutations in the Drosophila Lamin C (LamC) gene, an orthologue of human LMNA. The muscle-specific expression of the R527P equivalent showed cytoplasmic aggregation of LamC, a reduced larval muscle size, decreased larval motility, and cardiac defects resulting in a reduced adult lifespan. By contrast, the muscle-specific expression of the R482W equivalent caused an abnormal nuclear shape without a change in larval muscle size, larval motility, and adult lifespan compared to controls. Collectively, these studies identified fundamental differences in the properties of mutant lamins that cause clinically distinct phenotypes, providing insights into disease mechanisms.
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Affiliation(s)
- Sydney G Walker
- Department of Biochemistry and Molecular Biology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Christopher J Langland
- Department of Biochemistry and Molecular Biology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Jill Viles
- Independent Researcher, Gowrie, IA 50543, USA
| | - Laura A Hecker
- Department of Biology, Clarke University, Dubuque, IA 52001, USA
| | - Lori L Wallrath
- Department of Biochemistry and Molecular Biology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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Wang J, Morgan W, Saini A, Liu T, Lough J, Han L. Single-cell transcriptomic profiling reveals specific maturation signatures in human cardiomyocytes derived from LMNB2-inactivated induced pluripotent stem cells. Front Cell Dev Biol 2022; 10:895162. [PMID: 36518540 PMCID: PMC9742441 DOI: 10.3389/fcell.2022.895162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 11/02/2022] [Indexed: 11/19/2023] Open
Abstract
Mammalian cardiomyocyte maturation entails phenotypic and functional optimization during the late fetal and postnatal phases of heart development, both processes driven and coordinated by complex gene regulatory networks. Cardiomyocytes derived from human induced pluripotent stem cells (iPSCs) are heterogenous and immature, barely resembling their adult in vivo counterparts. To characterize relevant developmental programs and maturation states during human iPSC-cardiomyocyte differentiation, we performed single-cell transcriptomic sequencing, which revealed six cardiomyocyte subpopulations, whose heterogeneity was defined by cell cycle and maturation states. Two of those subpopulations were characterized by a mature, non-proliferative transcriptional profile. To further investigate the proliferation-maturation transition in cardiomyocytes, we induced loss-of-function of LMNB2, which represses cell cycle progression in primary cardiomyocytes in vivo. This resulted in increased maturation in LMNB2-inactivated cardiomyocytes, characterized by transcriptional profiles related to myofibril structure and energy metabolism. Furthermore, we identified maturation signatures and maturational trajectories unique for control and LMNB2-inactivated cardiomyocytes. By comparing these datasets with single-cell transcriptomes of human fetal hearts, we were able to define spatiotemporal maturation states in human iPSC-cardiomyocytes. Our results provide an integrated approach for comparing in vitro-differentiated cardiomyocytes with their in vivo counterparts and suggest a strategy to promote cardiomyocyte maturation.
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Affiliation(s)
- Jie Wang
- Department of Biostatistics and Bioinformatics, Roswell Park Comprehensive Cancer Center, Buffalo, NY, United States
| | - William Morgan
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
- Division of Pediatric Cardiology, Herma Heart Institute, Children’s Hospital of Wisconsin, Milwaukee, WI, United States
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Ankur Saini
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
- Division of Pediatric Cardiology, Herma Heart Institute, Children’s Hospital of Wisconsin, Milwaukee, WI, United States
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Tao Liu
- Department of Biostatistics and Bioinformatics, Roswell Park Comprehensive Cancer Center, Buffalo, NY, United States
| | - John Lough
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Lu Han
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
- Division of Pediatric Cardiology, Herma Heart Institute, Children’s Hospital of Wisconsin, Milwaukee, WI, United States
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
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Effect of the First Feeding on Enterocytes of Newborn Rats. Int J Mol Sci 2022; 23:ijms232214179. [PMID: 36430658 PMCID: PMC9699143 DOI: 10.3390/ijms232214179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/06/2022] [Accepted: 11/11/2022] [Indexed: 11/18/2022] Open
Abstract
The transcytosis of lipids through enterocytes occurs through the delivery of lipid micelles to the microvilli of enterocytes, consumption of lipid derivates by the apical plasma membrane (PM) and then their delivery to the membrane of the smooth ER attached to the basolateral PM. The SER forms immature chylomicrons (iChMs) in the ER lumen. iChMs are delivered at the Golgi complex (GC) where they are subjected to additional glycosylation resulting in maturation of iChMs. ChMs are secreted into the intercellular space and delivered into the lumen of lymphatic capillaries (LCs). The overloading of enterocytes with lipids induces the formation of lipid droplets inside the lipid bilayer of the ER membranes and transcytosis becomes slower. Here, we examined components of the enterocyte-to-lymphatic barriers in newly born rats before the first feeding and after it. In contrast to adult animals, enterocytes of newborns rats exhibited apical endocytosis and a well-developed subapical endosomal tubular network. These enterocytes uptake membranes from amniotic fluid. Then these membranes are transported across the polarized GC and secreted into the intercellular space. The enterocytes did not contain COPII-coated buds on the granular ER. The endothelium of blood capillaries situated near the enterocytes contained only a few fenestrae. The LCs were similar to those in adult animals. The first feeding induced specific alterations of enterocytes, which were similar to those observed after the lipid overloading of enterocytes in adult rats. Enlarged chylomicrons were stopped at the level of the LAMP2 and Neu1 positive post-Golgi structures, secreted, fused, delivered to the interstitial space, captured by the LCs and transported to the lymph node, inducing the movement of macrophages from lymphatic follicles into its sinuses. The macrophages captured the ChMs, preventing their delivery into the blood.
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