1
|
Brinkmeier ML, Wang SQ, Pittman H, Cheung LY, Prasov L. Myelin regulatory factor ( Myrf ) is a critical early regulator of retinal pigment epithelial development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.26.591281. [PMID: 38746430 PMCID: PMC11092522 DOI: 10.1101/2024.04.26.591281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Myelin regulatory factor (Myrf) is a critical transcription factor in early retinal and retinal pigment epithelial development, and human variants in MYRF are a cause for nanophthalmos. Single cell RNA sequencing (scRNAseq) was performed on Myrf conditional knockout mice ( Rx>Cre Myrf fl/fl ) at 3 developmental timepoints. Myrf was expressed specifically in the RPE, and expression was abrogated in Rx>Cre Myrf fl/fl eyes. scRNAseq analysis revealed a loss of RPE cells at all timepoints resulting from cell death. GO-term analysis in the RPE revealed downregulation of melanogenesis and anatomic structure morphogenesis pathways, which were supported by electron microscopy and histologic analysis. Novel structural target genes including Ermn and Upk3b , along with macular degeneration and inherited retinal disease genes were identified as downregulated, and a strong upregulation of TGFß/BMP signaling and effectors was observed. Regulon analysis placed Myrf downstream of Pax6 and Mitf and upstream of Sox10 in RPE differentiation. Together, these results suggest a strong role for Myrf in the RPE maturation by regulating melanogenesis, cell survival, and cell structure, in part acting through suppression of TGFß signaling and activation of Sox10 . SUMMARY STATEMENT Myrf regulates RPE development, melanogenesis, and is important for cell structure and survival, in part through regulation of Ermn , Upk3b and Sox10, and BMP/TGFb signaling.
Collapse
|
2
|
A Human Retinal Pigment Epithelium-Based Screening Platform Reveals Inducers of Photoreceptor Outer Segments Phagocytosis. Stem Cell Reports 2020; 15:1347-1361. [PMID: 33242397 PMCID: PMC7724476 DOI: 10.1016/j.stemcr.2020.10.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/28/2020] [Accepted: 10/30/2020] [Indexed: 11/20/2022] Open
Abstract
Phagocytosis is a key function in various cells throughout the body. A deficiency in photoreceptor outer segment (POS) phagocytosis by the retinal pigment epithelium (RPE) causes vision loss in inherited retinal diseases and possibly age-related macular degeneration. To date, there are no effective therapies available aiming at recovering the lost phagocytosis function. Here, we developed a high-throughput screening assay based on RPE derived from human embryonic stem cells (hRPE) to reveal enhancers of POS phagocytosis. One of the hits, ramoplanin (RM), reproducibly enhanced POS phagocytosis and ensheathment in hRPE, and enhanced the expression of proteins known to regulate membrane dynamics and ensheathment in other cell systems. Additionally, RM rescued POS internalization defect in Mer receptor tyrosine kinase (MERTK) mutant hRPE, derived from retinitis pigmentosa patient induced pluripotent stem cells. Our platform, including a primary phenotypic screening phagocytosis assay together with orthogonal assays, establishes a basis for RPE-based therapy discovery aiming at a broad patient spectrum.
Collapse
|
3
|
Sustentacular Cell Enwrapment of Olfactory Receptor Neuronal Dendrites: An Update. Genes (Basel) 2020; 11:genes11050493. [PMID: 32365880 PMCID: PMC7291085 DOI: 10.3390/genes11050493] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/23/2020] [Accepted: 04/27/2020] [Indexed: 12/12/2022] Open
Abstract
The pseudostratified olfactory epithelium (OE) may histologically appear relatively simple, but the cytological relations among its cell types, especially those between olfactory receptor neurons (ORNs) and olfactory sustentacular cells (OSCs), prove more complex and variable than previously believed. Adding to the complexity is the short lifespan, persistent neurogenesis, and continuous rewiring of the ORNs. Contrary to the common belief that ORN dendrites are mostly positioned between OSCs, recent findings indicate a sustentacular cell enwrapped configuration for a majority of mature ORN dendrites at the superficial layer of the OE. After vertically sprouting out from the borderlines between OSCs, most of the immature ORN dendrites undergo a process of sideways migration and terminal maturation to become completely invaginated into and enwrapped by OSCs. Trailing the course of the dendritic sideways migration is the mesodendrite (mesentery of the enwrapped dendrite) made of closely apposed, cell junction connected plasma membrane layers of neighboring folds of the host sustentacular cell. Only a minority of the mature ORN dendrites at the OE apical surface are found at the borderlines between OSCs (unwrapped). Below I give a brief update on the cytoarchitectonic relations between the ORNs and OSCs of the OE. Emphasis is placed on the enwrapment of ORN dendrites by OSCs, on the sideways migration of immature ORN dendrites after emerging from the OE surface, and on the terminal maturation of the ORNs. Functional implications of ORN dendrite enwrapment and a comparison with myelination or Remak’s bundling of axons or axodendrites in the central and peripheral nervous system are also discussed.
Collapse
|
4
|
Raasakka A, Kursula P. Flexible Players within the Sheaths: The Intrinsically Disordered Proteins of Myelin in Health and Disease. Cells 2020; 9:cells9020470. [PMID: 32085570 PMCID: PMC7072810 DOI: 10.3390/cells9020470] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/16/2020] [Accepted: 02/16/2020] [Indexed: 02/07/2023] Open
Abstract
Myelin ensheathes selected axonal segments within the nervous system, resulting primarily in nerve impulse acceleration, as well as mechanical and trophic support for neurons. In the central and peripheral nervous systems, various proteins that contribute to the formation and stability of myelin are present, which also harbor pathophysiological roles in myelin disease. Many myelin proteins have common attributes, including small size, hydrophobic segments, multifunctionality, longevity, and regions of intrinsic disorder. With recent advances in protein biophysical characterization and bioinformatics, it has become evident that intrinsically disordered proteins (IDPs) are abundant in myelin, and their flexible nature enables multifunctionality. Here, we review known myelin IDPs, their conservation, molecular characteristics and functions, and their disease relevance, along with open questions and speculations. We place emphasis on classifying the molecular details of IDPs in myelin, and we correlate these with their various functions, including susceptibility to post-translational modifications, function in protein–protein and protein–membrane interactions, as well as their role as extended entropic chains. We discuss how myelin pathology can relate to IDPs and which molecular factors are potentially involved.
Collapse
Affiliation(s)
- Arne Raasakka
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, NO-5009 Bergen, Norway;
| | - Petri Kursula
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, NO-5009 Bergen, Norway;
- Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Aapistie 7A, FI-90220 Oulu, Finland
- Correspondence:
| |
Collapse
|
5
|
Faigle W, Cruciani C, Wolski W, Roschitzki B, Puthenparampil M, Tomas-Ojer P, Sellés-Moreno C, Zeis T, Jelcic I, Schaeren-Wiemers N, Sospedra M, Martin R. Brain Citrullination Patterns and T Cell Reactivity of Cerebrospinal Fluid-Derived CD4 + T Cells in Multiple Sclerosis. Front Immunol 2019; 10:540. [PMID: 31024521 PMCID: PMC6467957 DOI: 10.3389/fimmu.2019.00540] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 02/27/2019] [Indexed: 01/11/2023] Open
Abstract
Immune responses to citrullinated peptides have been described in autoimmune diseases like rheumatoid arthritis (RA) and multiple sclerosis (MS). We investigated the post-translational modification (PTM), arginine to citrulline, in brain tissue of MS patients and controls (C) by proteomics and subsequently the cellular immune response of cerebrospinal fluid (CSF)-infiltrating T cells to citrullinated and unmodified peptides of myelin basic protein (MBP). Using specifically adapted tissue extraction- and combined data interpretation protocols we could establish a map of citrullinated proteins by identifying more than 80 proteins with two or more citrullinated peptides in human brain tissue. We report many of them for the first time. For the already described citrullinated proteins MBP, GFAP, and vimentin, we could identify additional citrullinated sites. The number of modified proteins in MS white matter was higher than control tissue. Citrullinated peptides are considered neoepitopes that may trigger autoreactivity. We used newly identified epitopes and previously reported immunodominant myelin peptides in their citrullinated and non-citrullinated form to address the recognition of CSF-infiltrating CD4+ T cells from 22 MS patients by measuring proliferation and IFN-γ secretion. We did not detect marked responses to citrullinated peptides, but slightly more strongly to the non-modified version. Based on these data, we conclude that citrullination does not appear to be an important activating factor of a T cell response, but could be the consequence of an immune- or inflammatory response. Our approach allowed us to perform a deep proteome analysis and opens new technical possibilities to analyze complex PTM patterns on minute quantities of rare tissue samples.
Collapse
Affiliation(s)
- Wolfgang Faigle
- Neuroimmunology and MS Research Section, Neurology Clinic, University Zurich, University Hospital Zurich, Zurich, Switzerland
| | - Carolina Cruciani
- Neuroimmunology and MS Research Section, Neurology Clinic, University Zurich, University Hospital Zurich, Zurich, Switzerland
| | - Witold Wolski
- Functional Genomics Center Zurich, ETH Zurich & University of Zurich, Zurich, Switzerland
| | - Bernd Roschitzki
- Functional Genomics Center Zurich, ETH Zurich & University of Zurich, Zurich, Switzerland
| | - Marco Puthenparampil
- Neuroimmunology and MS Research Section, Neurology Clinic, University Zurich, University Hospital Zurich, Zurich, Switzerland
| | - Paula Tomas-Ojer
- Neuroimmunology and MS Research Section, Neurology Clinic, University Zurich, University Hospital Zurich, Zurich, Switzerland
| | - Carla Sellés-Moreno
- Neuroimmunology and MS Research Section, Neurology Clinic, University Zurich, University Hospital Zurich, Zurich, Switzerland
| | - Thomas Zeis
- Neurobiology, Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Ivan Jelcic
- Neuroimmunology and MS Research Section, Neurology Clinic, University Zurich, University Hospital Zurich, Zurich, Switzerland
| | - Nicole Schaeren-Wiemers
- Neurobiology, Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Mireia Sospedra
- Neuroimmunology and MS Research Section, Neurology Clinic, University Zurich, University Hospital Zurich, Zurich, Switzerland
| | - Roland Martin
- Neuroimmunology and MS Research Section, Neurology Clinic, University Zurich, University Hospital Zurich, Zurich, Switzerland
| |
Collapse
|
6
|
Zhang C, Wang F, Xie Z, Chen L, Sinkemani A, Yu H, Wu X. AMOT130 linking F-actin to YAP is involved in intervertebral disc degeneration. Cell Prolif 2018; 51:e12492. [PMID: 30039887 DOI: 10.1111/cpr.12492] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 06/11/2018] [Indexed: 12/14/2022] Open
Abstract
OBJECTIVES Dysregulation of YAP by the Hippo signalling is associated with intervertebral disc degeneration (IDD). However, the relationship between the F-actin and Hippo pathway in IDD, and their effects on YAP remain poorly understood. METHODS The characteristics of Hippo pathway and F-actin the in the NP (nucleus pulposus) and annulus fibrosus of immature, mature, ageing and disc degeneration model rats were observed by immunofluorescence, western blot and qPCR. Nucleus pulposus cells (NPCs) were transfected with lentivirus Sh-LATS A, Sh-LATS B and harvested for SA-β-gal staining, qPCR, western blotting and immunofluorescence staining to investigate the mechanism of Hippo pathway and F-actin interact in NPCs. RESULTS We observed moderate decreases in F-actin and YAP expression with age in healthy intervertebral discs (IVDs). F-actin stress fibres distributed throughout the cytoplasm disappeared following treatment with latrunculin B (Lat B), resulting in a punctate distribution. Depletion of large tumour suppressor homologues 1/2 (LATS1/2) did not decrease the rate of cellular senescence, and YAP remained in the cytoplasm following Lat B treatment. Furthermore, angiomotin 130 (AMOT130) was associated with F-actin through a conserved actin-binding domain to retain YAP in the cytoplasm. CONCLUSIONS This study showed that a mechanism by which Hippo pathway and F-actin synergize to modulate YAP activation and localization in the context of IDD and help to control NPCs proliferation.
Collapse
Affiliation(s)
- Cong Zhang
- Department of Spine Surgery, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China.,Surgery Research Center, School of Medicine, Southeast University, Nanjing, China
| | - Feng Wang
- Department of Spine Surgery, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China.,Surgery Research Center, School of Medicine, Southeast University, Nanjing, China
| | - Zhiyang Xie
- Department of Spine Surgery, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China
| | - Lu Chen
- Department of Spine Surgery, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China
| | - Arjun Sinkemani
- Department of Spine Surgery, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China
| | - Haomin Yu
- Department of Spine Surgery, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China
| | - Xiaotao Wu
- Department of Spine Surgery, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China.,Surgery Research Center, School of Medicine, Southeast University, Nanjing, China
| |
Collapse
|
7
|
Malamon JS, Kriete A. Integrated Systems Approach Reveals Sphingolipid Metabolism Pathway Dysregulation in Association with Late-Onset Alzheimer's Disease. BIOLOGY 2018; 7:biology7010016. [PMID: 29425116 PMCID: PMC5872042 DOI: 10.3390/biology7010016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 01/22/2018] [Accepted: 02/06/2018] [Indexed: 01/21/2023]
Abstract
Late-onset Alzheimer’s disease (LOAD) and age are significantly correlated such that one-third of Americans beyond 85 years of age are afflicted. We have designed and implemented a pilot study that combines systems biology approaches with traditional next-generation sequencing (NGS) analysis techniques to identify relevant regulatory pathways, infer functional relationships and confirm the dysregulation of these biological pathways in LOAD. Our study design is a most comprehensive systems approach combining co-expression network modeling derived from RNA-seq data, rigorous quality control (QC) standards, functional ontology, and expression quantitative trait loci (eQTL) derived from whole exome (WES) single nucleotide variant (SNV) genotype data. Our initial results reveal several statistically significant, biologically relevant genes involved in sphingolipid metabolism. To validate these findings, we performed a gene set enrichment analysis (GSEA). The GSEA revealed the sphingolipid metabolism pathway and regulation of autophagy in association with LOAD cases. In the execution of this study, we have successfully tested an integrative approach to identify both novel and known LOAD drivers in order to develop a broader and more detailed picture of the highly complex transcriptional and regulatory landscape of age-related dementia.
Collapse
Affiliation(s)
- John Stephen Malamon
- Bossone Research Center, School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA.
| | - Andres Kriete
- Bossone Research Center, School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA.
| |
Collapse
|
8
|
Liang F. Olfactory receptor neuronal dendrites become mostly intra-sustentacularly enwrapped upon maturity. J Anat 2018; 232:674-685. [PMID: 29313978 DOI: 10.1111/joa.12777] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2017] [Indexed: 10/18/2022] Open
Abstract
The mammalian olfactory epithelium (OE) sustains persistent neurogenesis even in the adult. Sustentacular cells therein play both epithelial and neuroglial roles, although their relation with olfactory receptor neurons (ORNs) and their function in ORN maturation remain insufficiently understood. Sustentacular wrapping of ORN dendrites has been long known but always considered a minor presence, as opposed to the supposedly unwrapped majority of ORN dendrites at inter-sustentacular borderlines. Using immunofluorescence, confocal and immuno-electron microscopy, the current study examined cytoarchitectonic organization and maturation of ORN dendrites at the rat OE apical layer. Contrary to common belief, the observations here on tangential histological sections of the OE apical junctional belt layer showed on average 53.93% sustentacular cell-enwrapped, 18.46% partially wrapped (in the vertical grooves on the sides of sustentacular apices) and 27.61% unwrapped ORN dendrites (at the borderlines between sustentacular cells). The enwrapped dendrites were found within the confines of sustentacular apices but linked to the sides of the latter each by a mesentery (mesodendrite) of sustentacular plasma membranes and autotypic cell junctions. Up to six dendrites were seen in one sustentacular apical process. As marked by high and low immunoreactivity for class III beta-tubulin, respectively, immature and mature ORN dendrites accounted on average for 12.46 and 87.54% of the total ORN dendrites at the OE apical layer. By correlative analysis of the maturity level and wrapping status, most immature ORN dendrites were found unwrapped (immature unwrapped = 9.71% of the total dendrites), and practically no immature dendrites appeared enwrapped. In contrast, mature ORN dendrites comprised all the enwrapped (mature enwrapped = 53.93% of the total), most of the partially wrapped (mature partially wrapped = 15.71% of the total) and a portion of the unwrapped ORN dendrites (mature unwrapped = 17.9% of the total dendrites). Based on the current findings and previous data by other researchers, it is concluded that immature ORN dendrites emerge vertically from the OE apical surface between sustentacular cell apices. A large majority of the newly emerged dendrites then undergo sideways migration, sustentacular enwrapment and further maturation. Only a small minority of the newly emerged dendrites reach maturity and remain unwrapped. These divergent maturational courses imply structural or functional differences between the enwrapped and unwrapped mature ORN dendrites.
Collapse
Affiliation(s)
- Fengyi Liang
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| |
Collapse
|