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Ohguro H, Watanabe M, Hikage F, Sato T, Nishikiori N, Umetsu A, Higashide M, Ogawa T, Furuhashi M. Fatty Acid-Binding Protein 4-Mediated Regulation Is Pivotally Involved in Retinal Pathophysiology: A Review. Int J Mol Sci 2024; 25:7717. [PMID: 39062961 PMCID: PMC11277531 DOI: 10.3390/ijms25147717] [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: 06/01/2024] [Revised: 07/09/2024] [Accepted: 07/11/2024] [Indexed: 07/28/2024] Open
Abstract
Fatty acid-binding proteins (FABPs), a family of lipid chaperone molecules that are involved in intracellular lipid transportation to specific cellular compartments, stimulate lipid-associated responses such as biological signaling, membrane synthesis, transcriptional regulation, and lipid synthesis. Previous studies have shown that FABP4, a member of this family of proteins that are expressed in adipocytes and macrophages, plays pivotal roles in the pathogenesis of various cardiovascular and metabolic diseases, including diabetes mellitus (DM) and hypertension (HT). Since significant increases in the serum levels of FABP4 were detected in those patients, FABP4 has been identified as a crucial biomarker for these systemic diseases. In addition, in the field of ophthalmology, our group found that intraocular levels of FABP4 (ioFABP4) and free fatty acids (ioFFA) were substantially elevated in patients with retinal vascular diseases (RVDs) including proliferative diabetic retinopathy (PDR) and retinal vein occlusion (RVO), for which DM and HT are also recognized as significant risk factors. Recent studies have also revealed that ioFABP4 plays important roles in both retinal physiology and pathogenesis, and the results of these studies have suggested potential molecular targets for retinal diseases that might lead to future new therapeutic strategies.
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Affiliation(s)
- Hiroshi Ohguro
- Departments of Ophthalmology, School of Medicine, Sapporo Medical University, S1W17, Chuo-ku, Sapporo 060-8556, Japan; (M.W.); (F.H.); (N.N.); (A.U.); (M.H.)
| | - Megumi Watanabe
- Departments of Ophthalmology, School of Medicine, Sapporo Medical University, S1W17, Chuo-ku, Sapporo 060-8556, Japan; (M.W.); (F.H.); (N.N.); (A.U.); (M.H.)
| | - Fumihito Hikage
- Departments of Ophthalmology, School of Medicine, Sapporo Medical University, S1W17, Chuo-ku, Sapporo 060-8556, Japan; (M.W.); (F.H.); (N.N.); (A.U.); (M.H.)
| | - Tatsuya Sato
- Departments of Cardiovascular, Renal and Metabolic Medicine, Sapporo Medical University, S1W17, Chuo-ku, Sapporo 060-8556, Japan; (T.S.); (T.O.)
- Departments of Cellular Physiology and Signal Transduction, Sapporo Medical University, S1W17, Chuo-ku, Sapporo 060-8556, Japan
| | - Nami Nishikiori
- Departments of Ophthalmology, School of Medicine, Sapporo Medical University, S1W17, Chuo-ku, Sapporo 060-8556, Japan; (M.W.); (F.H.); (N.N.); (A.U.); (M.H.)
| | - Araya Umetsu
- Departments of Ophthalmology, School of Medicine, Sapporo Medical University, S1W17, Chuo-ku, Sapporo 060-8556, Japan; (M.W.); (F.H.); (N.N.); (A.U.); (M.H.)
| | - Megumi Higashide
- Departments of Ophthalmology, School of Medicine, Sapporo Medical University, S1W17, Chuo-ku, Sapporo 060-8556, Japan; (M.W.); (F.H.); (N.N.); (A.U.); (M.H.)
| | - Toshifumi Ogawa
- Departments of Cardiovascular, Renal and Metabolic Medicine, Sapporo Medical University, S1W17, Chuo-ku, Sapporo 060-8556, Japan; (T.S.); (T.O.)
- Departments of Cellular Physiology and Signal Transduction, Sapporo Medical University, S1W17, Chuo-ku, Sapporo 060-8556, Japan
| | - Masato Furuhashi
- Departments of Cardiovascular, Renal and Metabolic Medicine, Sapporo Medical University, S1W17, Chuo-ku, Sapporo 060-8556, Japan; (T.S.); (T.O.)
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Umetsu A, Furuhashi M, Watanabe M, Ohkawa E, Tsugeno Y, Suzuki S, Itoh K, Ida Y, Hikage F, Ohguro H. Fatty acid metabolism is involved in both retinal physiology and the pathology of retinal vascular diseases. Prostaglandins Leukot Essent Fatty Acids 2022; 183:102473. [PMID: 35820353 DOI: 10.1016/j.plefa.2022.102473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/23/2022] [Accepted: 07/04/2022] [Indexed: 12/29/2022]
Abstract
To study the pathophysiological roles of the fatty acid-binding proteins (FABPs) within the retina, we performed; (1) immunolabeling of human retinas, wild type (WT) rat and mouse retinas, rat models for diabetic retinopathy (DR) and retinitis pigmentosa (RP) with anti-FABP3, FABP4, FABP5, FABP7, FABP8 and FABP12, (2) electroretinogram (ERG) measurements of WT and FABP4-deficient (Fabp4-/-) mice, (3) ELISA or gas chromatography measurements of plasma (P-) and vitreous (V-) levels of FABP4 and vascular endothelial growth factor A (VEGFA), and fatty acids (FAs) from patients with retinal vascular disease (RVD) including proliferative DR (PDR, n = 30) and retinal vein occlusion (RVO, n = 18) and non-RVD (n = 18). Within the human retina, diverse expressions of FABP3, FABP4, FABP7 and FABP8 were identified. In contrast, positive immunoreactivities toward only FABP4 and FABP12 were detected in the cases of rat and mouse retinas, and interestingly, the FABP4 labeling patterns for the WT, DR and RP rat retinas were different. The ERG amplitudes of Fabp4-/- mice were enhanced compared with those of WT mice. The concentrations of V-FABP4, V-VEGFA and total FAs were significantly higher in RVD patients than in non-PDR patients (P < 0.05). The V-FAs levels of each were significantly and positively correlated with V-FABP4 and V-VEGFA, although no significant correlation between vitreous (V-) and plasma (P-) FABP4, VEGFA and FAs were detected. The current study reveals that V-FAs appear to have significant roles in both retinal physiology as well as the pathogenesis of RVD with FABP4, which is commonly expressed within the retina in most species.
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Affiliation(s)
- Araya Umetsu
- Department of Ophthalmology, Sapporo Medical University School of Medicine, Japan
| | - Masato Furuhashi
- Cardiovascular, Renal and Metabolic Medicine, Sapporo Medical University School of Medicine, Japan
| | - Megumi Watanabe
- Department of Ophthalmology, Sapporo Medical University School of Medicine, Japan
| | - Ei Ohkawa
- Department of Ophthalmology, Sapporo Medical University School of Medicine, Japan
| | - Yuri Tsugeno
- Department of Ophthalmology, Sapporo Medical University School of Medicine, Japan
| | - Soma Suzuki
- Department of Ophthalmology, Sapporo Medical University School of Medicine, Japan
| | - Kaku Itoh
- Department of Ophthalmology, Sapporo Medical University School of Medicine, Japan
| | - Yosuke Ida
- Department of Ophthalmology, Sapporo Medical University School of Medicine, Japan
| | - Fumihito Hikage
- Department of Ophthalmology, Sapporo Medical University School of Medicine, Japan
| | - Hiroshi Ohguro
- Department of Ophthalmology, Sapporo Medical University School of Medicine, Japan.
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Campbell WA, Tangeman A, El-Hodiri HM, Hawthorn EC, Hathoot M, Blum S, Hoang T, Blackshaw S, Fischer AJ. Fatty acid-binding proteins and fatty acid synthase influence glial reactivity and promote the formation of Müller glia-derived progenitor cells in the chick retina. Development 2022; 149:274285. [PMID: 35132991 PMCID: PMC8959147 DOI: 10.1242/dev.200127] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 01/18/2022] [Indexed: 11/20/2022]
Abstract
A recent comparative transcriptomic study of Müller glia (MG) in vertebrate retinas revealed that fatty acid binding proteins (FABPs) are among the most highly expressed genes in chick ( Hoang et al., 2020). Here, we investigate how FABPs and fatty acid synthase (FASN) influence glial cells in the chick retina. During development, FABP7 is highly expressed by retinal progenitor cells and maturing MG, whereas FABP5 is upregulated in maturing MG. PMP2 (FABP8) is expressed by oligodendrocytes and FABP5 is expressed by non-astrocytic inner retinal glial cells, and both of these FABPs are upregulated by activated MG. In addition to suppressing the formation of Müller glia-derived progenitor cells (MGPCs), we find that FABP-inhibition suppresses the proliferation of microglia. FABP-inhibition induces distinct changes in single cell transcriptomic profiles, indicating transitions of MG from resting to reactive states and suppressed MGPC formation, with upregulation of gene modules for gliogenesis and decreases in neurogenesis. FASN-inhibition increases the proliferation of microglia and suppresses the formation of MGPCs. We conclude that fatty acid metabolism and cell signaling involving fatty acids are important in regulating the reactivity and dedifferentiation of MG, and the proliferation of microglia and MGPCs.
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Affiliation(s)
- Warren A Campbell
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Allen Tangeman
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Heithem M El-Hodiri
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Evan C Hawthorn
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Maddie Hathoot
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Sydney Blum
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Thanh Hoang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Andy J Fischer
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
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Finnegan S, Robson JL, Wylie M, Healy A, Stitt AW, Curry WJ. Protein expression profiling during chick retinal maturation: a proteomics-based approach. Proteome Sci 2008; 6:34. [PMID: 19077203 PMCID: PMC2648947 DOI: 10.1186/1477-5956-6-34] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Accepted: 12/10/2008] [Indexed: 11/16/2022] Open
Abstract
Background The underlying pathways that drive retinal neurogenesis and synaptogenesis are still relatively poorly understood. Protein expression analysis can provide direct insight into these complex developmental processes. The aim of this study was therefore to employ proteomic analysis to study the developing chick retina throughout embryonic (E) development commencing at day 12 through 13, 17, 19 and post-hatch (P) 1 and 33 days. Results 2D proteomic and mass spectrometric analysis detected an average of 1514 spots per gel with 15 spots demonstrating either modulation or constitutive expression identified via MS. Proteins identified included alpha and beta-tubulin, alpha enolase, B-creatine kinase, gamma-actin, platelet-activating factor (PAF), PREDICTED: similar to TGF-beta interacting protein 1, capping protein (actin filament muscle Z line), nucleophosmin 1 (NPM1), dimethylarginine dimethylaminohydrolase, triosphoaphate isomerase, DJ1, stathmin, fatty acid binding protein 7 (FABP7/B-FABP), beta-synuclein and enhancer of rudimentary homologue. Conclusion This study builds upon previous proteomic investigations of retinal development and represents the addition of a unique data set to those previously reported. Based on reported bioactivity some of the identified proteins are most likely to be important to normal retinal development in the chick. Continued analysis of the dynamic protein populations present at the early stages and throughout retinal development will increase our understanding of the molecular events underpinning retinogenesis.
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Affiliation(s)
- Sorcha Finnegan
- Centre for Vision Sciences, Queen's University of Belfast, Institute of Clinical Sciences, Royal Victoria Hospital, Belfast, Northern Ireland.
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Chang ML, Wu CH, Jiang-Shieh YF, Shieh JY, Wen CY. Reactive changes of retinal astrocytes and Müller glial cells in kainate-induced neuroexcitotoxicity. J Anat 2007; 210:54-65. [PMID: 17229283 PMCID: PMC2100256 DOI: 10.1111/j.1469-7580.2006.00671.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The aim of this study was to investigate reactive changes of astrocytes and Müller glial cells in rats subjected to kainate treatment, which leads to neuronal degeneration in the ganglion cell layer and the inner border of the inner nuclear layer as confirmed by labelling with Fluoro-Jade B, a marker for degenerating neurons and fibres. Both the astrocytes and the Müller glial cells reacted vigorously to kainate injection as shown by their up-regulated expression of nestin, glial fibrillary acidic protein and glutamine synthetase. A major finding was the induced expression of nestin together with glial fibrillary acidic protein beginning at 1 day post-injection of kainate. The marked nestin expression appeared to be most intense at 1 day and was sustained till 2 weeks as compared with the untreated/normal retina. Western blotting analysis confirmed a marked increase in expression of nestin, glial fibrillary acidic protein and glutamine synthetase as compared with untreated/normal retina. Double labelling study revealed that astrocytes and Müller glial cells expressed the radial glia marker nestin, and incorporated bromodeoxyuridine to re-enter into their cell cycle. The induced expression of these proteins in astrocytes and Müller glial cells indicated an induction of gliotic responses and de-differentiation that may be associated with regenerative efforts after kainate-induced injury. Indeed, with the acquisition of an immature molecular profile as manifested by the induced expression of brain lipid-binding protein and doublecortin in astrocytes and Müller glial cells, the potential of these cells to de-differentiate in retinal neurodegeneration is greatly amplified.
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Affiliation(s)
- Min-Lin Chang
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan UniversityTaipei, Taiwan
| | - Ching-Hsiang Wu
- Department of Biology and Anatomy, National Defense Medical CenterTaipei, Taiwan
| | - Ya-Fen Jiang-Shieh
- Department of Anatomy, College of Medicine, National Cheng Kung UniversityTaiwan
| | - Jeng-Yung Shieh
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan UniversityTaipei, Taiwan
| | - Chen-Yuan Wen
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan UniversityTaipei, Taiwan
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Helle T, Deiss S, Schwarz U, Schlosshauer B. Glial and neuronal regulation of the lipid carrier R-FABP. Exp Cell Res 2003; 287:88-97. [PMID: 12799185 DOI: 10.1016/s0014-4827(03)00109-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Neuroembryogenesis critically depends on signaling molecules that modulate cell proliferation, differentiation, and the formation of neural networks. In an attempt to identify potential morphogenetic active components that are distributed in a graded fashion in the developing nervous system, we generated substraction libraries of the embryonic nasal and temporal chick retina. Selected clones were analyzed by sequencing, Northern and Western blotting, in situ hybridization, and immunocytochemistry. Retinal fatty acid-binding protein (R-FABP) mRNA displayed the most pronounced topographic gradient. R-FABP was most strongly expressed in nasal retina, though topographic differences were not evident on the protein level. R-FABP expression was subject to a pronounced spatio-temporal regulation. Peak expression was at the period of cell generation/migration and differentiation. To identify the cell types involved in R-FAPB synthesis, ganglion cells as the only retinal projection neurons were enriched by enzymatic delayering. Cell somata, axons, and growth cones were R-FABP immunoreactive. Most interestingly, R-FABP immunoreactivity was critically dependent on the growth substratum. It was abrogated when axons grew on isolated glial endfeet. Radial glia purified by complement-mediated cytolysis also expressed R-FABP at moderate levels. The expression level was significantly increased during mitosis and dropped down again in postmitotic cells. Further on, transient loss of cell-cell and substratum contact induced a subcellular redistribution of R-FABP. In conjunction with the morphogen-binding activity of other FABP family members and their impact on cell migration and tissue differentiation, R-FABP characteristics suggest a regulatory function during retinal histogenesis but not during topographic map formation.
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Affiliation(s)
- Thomas Helle
- Max-Planck-Institute for Developmental Biology, Spemannstrasse 35/Abt. II; D-72076, Tuebingen, Germany
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Allen GW, Liu J, Kirby MA, De León M. Induction and axonal localization of epithelial/epidermal fatty acid-binding protein in retinal ganglion cells are associated with axon development and regeneration. J Neurosci Res 2001; 66:396-405. [PMID: 11746357 DOI: 10.1002/jnr.1232] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Epithelial/epidermal fatty acid-binding protein (E-FABP) is induced in peripheral neurons during nerve regeneration and is found at high levels in central neurons during neuronal migration and development. Furthermore, E-FABP expression is required for normal neurite outgrowth in PC12 cells treated with nerve growth factor (NGF). The present study examined whether E-FABP plays a role in retinal ganglion cell (RGC) differentiation and axon growth. Rat retinal tissues from embryonic (E) and postnatal (P) development through adulthood were examined using immunocytochemical labeling with E-FABP and growth-associated protein 43 (GAP-43) antibodies. E-FABP colocalized with GAP-43 at E14 through P10. At E14, E-FABP immunoreactivity was confined to the somas of GAP-43-positive cells in the ganglion cell layer, but it was localized to their axons by E15. The axons in the optic nerve were GAP-43-positive and E-FABP-negative on E15, but the two proteins were colocalized by E18. Retinal cultures at E15 confirmed that E-FABP and GAP-43 colocalize in RGCs. Postnatally, labeling was present between P1 and P10 but decreased at older ages and was minimally present or absent in adult animals. Western immunoblotting revealed that at E18, P1, and P10 E-FABP levels were at least fourfold greater than those in the adult. By P15, protein levels were only twofold greater, with adult levels reached by P31. Furthermore, E-FABP could be reinduced during axon regeneration. Dissociated P15 retinal cells cultured in the presence of brain-derived neurotrophic factor, ciliary neurotrophic factor, and basic fibroblast growth factor exhibited sixfold more GAP-43 and E-FABP double-positive RGCs (cell body and axons) than controls. Moreover, all GAP-43-immunoreactive RGCs were also positive for E-FABP. Taken together, these results indicate the following: 1) E-FABP is expressed in RGCs as they reached the ganglion cell layer and 2) E-FABP plays a functional role in the elaboration of RGC axons in both development and regeneration.
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Affiliation(s)
- G W Allen
- Department of Physiology and Pharmacology, Center for Molecular Biology and Gene Therapy, Loma Linda University, Loma Linda, California 92350, USA
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Liu Y, Longo LD, De León M. In situ and immunocytochemical localization of E-FABP mRNA and protein during neuronal migration and differentiation in the rat brain. Brain Res 2000; 852:16-27. [PMID: 10661491 DOI: 10.1016/s0006-8993(99)02158-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The present study compares the temporal-spatial expression and tissue localization of the rat epidermal type fatty acid binding protein (E-FABP) (DA11/C-FABP/S-FABP/LEBP/KLBP) in the developing rat central nervous system (CNS). In situ hybridization (ISH) and immunocytochemistry (ICC) studies demonstrate that mRNA E-FABP and protein are expressed at high levels during neurogenesis, neuronal migration, and terminal differentiation. Migrating pyramidal cells in the cerebral cortex, Purkinje cells and deep nuclear neurons in the cerebellum, and neurons in the olfactory bulb and retina exhibited a strong E-FABP-like immunoreactivity (E-FABP-LI) throughout the entire process of differentiation and migration. The levels of E-FABP mRNA and protein were dramatically higher in prenatal and early postnatal neurons, as compared to adult neurons. The E-FABP antibody immunoreacted with growing neurites, and nuclear and cytoplasmic regions of neurons. The intracellular multiregional pattern of localization of E-FABP and its differential temporal expression during development, are consistent with its proposed role in transporting long chain free fatty acids and/or other hydrophobic ligands during neuronal differentiation and axon growth.
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Affiliation(s)
- Y Liu
- Department of Physiology and Pharmacology, School of Medicine, Loma Linda University, CA 92354, USA
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Rodriguez de Turco EB, Parkins N, Ershov AV, Bazan NG. Selective retinal pigment epithelial cell lipid metabolism and remodeling conserves photoreceptor docosahexaenoic acid following phagocytosis. J Neurosci Res 1999. [DOI: 10.1002/(sici)1097-4547(19990815)57:4<479::aid-jnr7>3.0.co;2-u] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Liu Y, Molina CA, Welcher AA, Longo LD, De Leon M. Expression of DA11, a neuronal-injury-induced fatty acid binding protein, coincides with axon growth and neuronal differentiation during central nervous system development. J Neurosci Res 1997; 48:551-62. [PMID: 9210525 DOI: 10.1002/(sici)1097-4547(19970615)48:6<551::aid-jnr8>3.0.co;2-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
DA11 is the first fatty acid binding protein (FABP) for which gene expression has been shown to be upregulated following neuronal injury in the adult peripheral nervous system. To understand better the potential regulatory role(s) of this unique FABP in axonal growth and neuronal differentiation, we undertook a temporal and spatial study of DA11 gene expression in the developing rat central nervous system (CNS). Transient upregulation of DA11 mRNA and protein levels in CNS tissues were quantified by Northern blot hybridization and Western immunoblot analyses at different developmental ages. Homogenates of embryonic and neonatal cerebral cortex, cerebellum, brain stem, and hippocampal tissues contained 100-fold more DA11 mRNA and protein than corresponding adult tissues. Significant increase in DA11 mRNA was observed as early as embryonic day (E) 14 in cerebral cortex and cerebellum and E19 in brain stem and hippocampus. Postnatal levels of DA11 remained elevated through postnatal day (P) 10 in cerebral cortex, P14 in brain stem and hippocampus, and P20 in cerebellum. Localization of DA11-like immunoreactivity to specific CNS tissues, cell types, and intracellular compartments at P9 revealed a spatial pattern of neuronal expression different than that reported for other FABPs. DA11 protein was detected in the nucleus, cytoplasm, axons, and dendrites of differentiating neurons in cerebral cortex, hippocampus, cerebellum, brain stem, spinal cord, and olfactory bulb. The strong association of DA11 gene expression with development throughout the CNS suggests that this unique FABP plays an important role in axonal growth and neuronal differentiation in many different neuronal populations.
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Affiliation(s)
- Y Liu
- Department of Physiology and Pharmacology, Loma Linda University School of Medicine, California 92350, USA
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11
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Abstract
Fatty acid binding proteins (FABP) constitute a family of small, cytosolic carriers of hydrophobic ligands. These proteins are thought to be important for lipid trafficking toward specific metabolic pathways, and are potentially important for the establishment of characteristic lipid compositions of neural tissue. In the embryonic chick retina and brain, FABP resembles the heart subtype, as determined by protein characterization and immunoblot studies. In this paper, the developmental expression and cellular localization of chick retinal FABP were examined. Results of immunoblot analysis suggest that FABP is maximally expressed around embryonic day 9 (E9) and declines thereafter. In adult retinas, FABP is barely detectable on a Western blot. Immunohistochemical staining of the retina shows light labeling on day E6 and a more intense staining throughout the retina on day E9. As the retina differentiates, labeling becomes increasingly localized. By day E18 subpopulations of ganglion cells and photoreceptor inner segments are stained, as are all photoreceptor cell bodies, most of the inner nuclear layer, and the nerve fiber layer. Staining is decreased in older retinas such that in adult animals, only light staining of the photoreceptor cell bodies is visible. The decrease in relative amount of FABP in the retina after day E9 suggests a role for FABP in the early stages of retinal differentiation. Localization in the retina is consistent with this hypothesis, as label becomes more restricted to those cells undergoing maturation at a particular developmental age. Thus, in young embryos (E6-E9), FABP immunolabeling is apparent throughout the retina, and transiently localizes at different ages (E12-E15) to plexiform and nuclear layers.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- P Sellner
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City 66160-7400
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