title: Calcium buffer proteins are specific markers of human retinal neurons.
abstract: Ca(2+)-buffer proteins (CaBPs) modulate the temporal and spatial characteristics of transient intracellular Ca(2+)-concentration changes in neurons in order to fine-tune the strength and duration of the output signal. CaBPs have been used as neurochemical markers to identify and trace neurons of several brain loci including the mammalian retina. The CaBP content of retinal neurons, however, varies between species and, thus, the results inferred from animal models cannot be utilised directly by clinical ophthalmologists. Moreover, the shortage of well-preserved human samples greatly impedes human retina studies at the cellular and network level. Our purpose has therefore been to examine the distribution of major CaBPs, including calretinin, calbindin-D28, parvalbumin and the recently discovered secretagogin in exceptionally well-preserved human retinal samples. Based on a combination of immunohistochemistry, Neurolucida tracing and Lucifer yellow injections, we have established a database in which the CaBP marker composition can be defined for morphologically identified cell types of the human retina. Hence, we describe the full CaBP make-up for a number of human retinal neurons, including HII horizontal cells, AII amacrine cells, type-1 tyrosine-hydroxylase-expressing amacrine cells and other lesser known neurons. We have also found a number of unidentified cells whose morphology remains to be characterised. We present several examples of the colocalisation of two or three CaBPs with slightly different subcellular distributions in the same cell strongly suggesting a compartment-specific division of labour of Ca(2+)-buffering by CaBPs. Our work thus provides a neurochemical framework for future ophthalmological studies and renders new information concerning the cellular and subcellular distribution of CaBPs for experimental neuroscience.
authors.affiliation: Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, H-1094, Hungary.|MTA-PTE NAP B Retinal Electrical Synapses Research Group, Pécs, H-7624, Hungary.
authors.forename: Orsolya
authors.identifier: 0000-0002-1388-8294
authors.initials: O
authors.lastname: Kántor
authors.affiliation: Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, H-1094, Hungary.
authors.forename: Szilvia
authors.initials: S
authors.lastname: Mezey
authors.affiliation: Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, H-1094, Hungary.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Adeghate
authors.affiliation: Life Imaging Center, Center for Biological Systems Analysis, Albert Ludwigs University, Freiburg, 79104, Germany.|BIOSS Centre for Biological Signaling Studies, Albert Ludwigs University, Freiburg, 79104, Germany.
authors.forename: Angela
authors.initials: A
authors.lastname: Naumann
authors.affiliation: Life Imaging Center, Center for Biological Systems Analysis, Albert Ludwigs University, Freiburg, 79104, Germany.|BIOSS Centre for Biological Signaling Studies, Albert Ludwigs University, Freiburg, 79104, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Nitschke
authors.affiliation: Department of Ophthalmology, Semmelweis University, Budapest, H-1085, Hungary.|Department of Human Morphology and Developmental Biology, Semmelweis University, Budapest, H-1094, Hungary.
authors.forename: Anna
authors.initials: A
authors.lastname: Énzsöly
authors.affiliation: Department of Human Morphology and Developmental Biology, Semmelweis University, Budapest, H-1094, Hungary.
authors.forename: Arnold
authors.initials: A
authors.lastname: Szabó
authors.affiliation: Department of Human Morphology and Developmental Biology, Semmelweis University, Budapest, H-1094, Hungary.
authors.forename: Ákos
authors.initials: Á
authors.lastname: Lukáts
authors.affiliation: Department of Ophthalmology, Semmelweis University, Budapest, H-1085, Hungary.
authors.forename: János
authors.initials: J
authors.lastname: Németh
authors.affiliation: Complex Systems and Computational Neuroscience Group, Wigner Research Center for Physics, Hungarian Academy of Sciences, Budapest, H-1121, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Somogyvári
authors.affiliation: MTA-PTE NAP B Retinal Electrical Synapses Research Group, Pécs, H-7624, Hungary. volgyi01@gamma.ttk.pte.hu.|Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, H-7624, Hungary. volgyi01@gamma.ttk.pte.hu.|Department of Ophthalmology, New York University Langone Medical Center, New York, NY 10016, USA. volgyi01@gamma.ttk.pte.hu.|Szentágothai Research Center, University of Pécs, Ifjúság Street 20, H-7624, Pécs, Hungary. volgyi01@gamma.ttk.pte.hu.
authors.forename: Béla
authors.initials: B
authors.lastname: Völgyi
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000378:metabolism*; D002021:Buffers; D064032:Calbindin 2 / Q000378:metabolism; D064026:Calbindins / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010320:Parvalbumins / Q000378:metabolism; D055351:Retinal Neurons / Q000166:cytology / Q000378:metabolism*; D064046:Secretagogins / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D015415:Biomarkers; D002021:Buffers; D064032:Calbindin 2; D064026:Calbindins; D002135:Calcium-Binding Proteins; D010320:Parvalbumins; D064046:Secretagogins; D014446:Tyrosine 3-Monooxygenase
keywords: Calbindin; Calretinin; Parvalbumin; Retina; Secretagogin