Non-membran ous cell organelles. Cytoskeleton – structure, function and tissue specificity.
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Transcript of Non-membran ous cell organelles. Cytoskeleton – structure, function and tissue specificity.
Non-membranous cell organelles.Cytoskeleton – structure, function
and tissue specificity. Specialization of the cell surface.
Intercellular junctions.Biological motors – molecular principles
Institute of Histology and EmbryologyAuthor: Prof. MUDr. Jindřich Martínek, DrSc.
Subject: General Histology and general embryology Code: 82241Date: 2013, October, 10th and 12th
NON-MEMBRANOUS CELL ORGANELLS
• NUCLEOLUS• RIBOSOME• CENTRIOLE• CYTOSKELETON
thin filaments - actin
intermediate filament
lamins (A, B, C)
cytokeratins (1 – 20)
desmin, vimentin
nestin
microtubules
Becker: The world of the cell, 1986
NON-MEMBRANOUS CELL ORGANELLES
• NUCLEOLUS – localization in the karyoplasm – nucleolar organizing centers (NORs) - two components (amorphous and granulous) – site of transcription of r-RNAs (ribosomal) – compact, network and ring-form type
• CENTRIOLE – specific organization of microtubeles (9 triplets) – MTOC – microtubular organizing center function, simple and multiple centriolar replication. Role in formation of mitotic and meiotic spindle and basal bodies of cilia and flagella
• CYTOSKELETON – complex of thin (5-7 nm) and intermediate (10-15 nm) filaments and microtubules (24 nm) – actin (thin) filaments with myosin and tubulins (of microtubules) with dynein and kinesin represent molecular motors for intracellular traffic – intermediate filaments are nonpolar – nestin, cytokeratins, vimentin, desmin – tissue specific – cells of epithelial origin (cytokeratin), mesenchymal origin (desmin), muscle tissue (vimentin)
• RIBOSOMES – (15-30 nm) composed of two subunits (small and large) – play a role in translation – protein synthesis – as free polysomes and membrane bounded (GER)
PF
PG
FC
PNC
PNC
Types: compact – initial transcription of rRNA at the single NORs; network – massive transcription in gradually confluent NORs ring-form – decreasing transcription at the single NOR
NUCLELUS – non-membranous cell organelle derived from activated parts of some chromosomes – nucleolar organizing regions (NORs) or nucleolar organizing centers (NOCs)
FC = fibrilar center – NOCPF = pars fibrosa – accumulated transcriptPG = pars granulosa – ribosomal assemblyPNC = perinucleolar chromatin
VISUALISATION OF NUCLEOLAR ORGANISERS USING IMMUNOHISTOCHEMICAL PROBES
TYPES OF NUCLEOLI:a) compact – currently activated nucleolar
organiser b) with nucleolonema – massive
formation of ribonucleoproteins
around NORs - typical network appearancec) ring form – decreased of RNA transcription in
the inactivated nucleolar organiser
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1
1 = perinucleolar chromatin 2 = nucleolar organiser3 = nucleolonemata 4 = nuclear channel system5 = lamelae annulatae 6 = lysosomes
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3
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RIBOSOMES (15 – 30 nm)
free polysomesGERPROTEIN SYNTHESIS
GER
NUCLEUS
NUCLEARPORES
GER
RIBOSOME – TRANSLATION MECHANISM – POLYSOMES
Start codon (AUG)
Currently translating codon (arbitrary)
Scheme of the protein synthesis on freepolysomes (Junqueira´s Basic Histology, Mesher, 2010)
ribosome
mRNA
free proteinin the cytoplasm
Electron micrograph: Histology, Ross, Pawlina 2010Arrows: free polysomesRough (Granular) Endoplasmic Reticulum rER (GER)
GER
GERGER
IMMUNOHISTOCHEMICAL DETECTION OF SOME CYTOSKELATAL COMPONENTSMicrotubules (red), actin filaments (green)– fluorescence microscope
CHARACTERISTICS OF CYTOSKELETAL COMPONENETS
Diameter: 6 – 8 nm 10 – 12 nm 24 nm
Composition: Polymer of G-actin Various proteins Dimers of α- and ß-tubulin
Structure: Double-stranded F-actin helix Ropelike fiber Hollow non-branched cylinder Thin flexible filament Strong, stable structure Exhibit dynamic instability Readily dissociate and reassamble Enzymeactivity: ATP hydrolitic activity None GTP hydrolytic activity
ATP-dependent polymeration GTP-dependent polymerationLocation and functionin the cell: Terminal web Extend across cytoplasm Core of cilia and flagellum Zonula adherens connecting desmosomes Centriole Core of microvilli and hemidesmosomes Mitotic spindle Contractile ring in the Nuclear lamina of nucleus Provide network “railroad dividing cell Support of cell processes tracks“ for movement of Contractile elements Provide mechanical strenght organelles within cell of muscles and resistence to shearing Movement cilia and forces chromosomes (during cell division
Ross, Pawlina: Histology, 2006
Actin filaments Intermediate filaments Microtubules
ACTINthin filaments (5 – 7 nm)G and F actin – ATP dependent
(poly- and depolamerization)
MOLECULAR MOTOR COMPONENTtogether with myosin
Smooth muscle cells
Hearth muscle cells - cardiomyocytes
FUNCTION OF MICROFILAMENTSAND MICROTUBULES IN REGULATIONSAND INTRACELLULAR TRAFIC
THE MOLECULAR MOTOR PROTEINS WORKING WITH MICROFILAMENTS (ACTIN)
Unipolarly organized myosin(myosin monomers – myosin I) –one way movement of cargo
Bipolar organization of myosin(myosin monomers – myosin II) –ontractile activity with oppositedirection movement of actinfilaments – muscle tissue
Unipolarly working myosin (I) –attached to the cytoplasmicmembrane – formation of pseudo-podia movement of cell
THE MOLECULAR MOTOR PROTEINS WORKING WITH TUBULINS OF MICROTUBULES
Scheme: Histology, Ross, Pawlina, 2010
Kinesins move along the MT tothe plus end and can transport cargo (organelles) from the cytocentrum toward the cell peripheryDyneins move along the MT to the minus end, transport cargo (endocytotic vesicles) from the cell periphery toward the MTOC.
INTERMEDIATE FILAMENTS – non-polar lamins A, B, C – nuclear lamina
cytokeratins – cells of germ layer origin
desmin – cells of mesenchymal origin
vimentin – cells of mesenchymal origin neurofilaments – nerve cells
GFAP – glial fibrillary associated protein (acidic) nestin – during cell development
CYTOKERATIN 18 – fission products – APOPTOTIC MARKER
MICROTUBULES (25 nm) tubulin α, β, γ (GTP – dependent polymerization)MOLECULAR MOTOR COMPONENT – together with dynein (+ -) and kinesin (- +)
CENTRIOLAR PAIR - CENTROSOMECILIUM – KINOCILIUM
Ross, Pawlina: Histology, 2006
CENTRIOLES AND CENTRIOLAR REPLICATION
SIMPLE REPLICATION – begins fromexisting centriolar pair
MULTIPLE REPLICATION – starts as synthesis of precursor material (tubulins)and continues as induced assembly of nine procentriolar triplets of microtubules – typical for cells with kinociliary apparatus at the apical surface
Centriolar pair = diplosome – centrosomeCentriole: Procentriole: = 200 nm = 200 nm L = 400 nm L = 200 – 400 nmCentriolar DNA – MTOC – centriolar precursors
Mucus layer
ZONULA OCCLUDENS – freeze fracturing technique
ZONULA OCCLUDENS – tight junctions – missing intercelluar space
RidgesGrooves
Ross, Pawlina: Histology, 2006
Ciliarynecklaces
Golgi complex
Zonula occludens
Desmosome – macula adherens
Cytokeratin – intermediate filaments
Zonula adherens
ZONULA ADHERENS – terminal web – transverally arranged actin filaments inserting via α-actinin and vinculin and catenin into E-cadherin moleculs
GAP JUNCTIONS – NEXUSSES –communicative cell to cell interconnectionsconnexon – canal formationconnexins – membrane proteins
MICROVILLI = 0.1 mlenght = 1 – 5 m – core – actin filamentsRegularly arranged and numerous microvillirepresent specific surface specialization of anabsorptive epithelium – brush border –at the apical pole of cells.Stereocilium – long and branched microvillus
Ross, Pawlina: Histology, 2006
Microvilli at the cell suface and intercellular interconnectionZO = zonula occludens; ZA = zonula adherens; D = desmosome
zoZA
D
SOLITARY (single or individual) CILIUM
Basal body
Axonemal complex
Ciliary sheatPinocytotic vesicle
= 0.25 mL = 3 – 5 (7) m (50 for tail of spermatozoon) Consist of basal body (9 triplets – MTOC) and axonemal complex (9 doubletsand 1 central pair of microtubules).Basal body develops from one ofcentrilar pair and therefore it is lo-cated often in the CYTOCENTRUM.
Ross, Pawlina: Histology, 2006
KINOCILIARY APPARATUS
Oviduct – simple columnar ciliated epithelium
Cilia and microvilliat the cross section
INTERDIGITATIONS
CILIA, MICROVILLI, JUNCTIONAL COMPLEXESAND TERMINAL WEB
IMMUNOFLUORESCENT DETECTIONOF PANCADHERIN IN SEMINIFEROUS TUBULES OF TESTIS (Zonulae adherentes)BETWEEN SERTOLI CELLS PROCESSES
BASOLATERAL LABYRINT
Typical for absorptive type ofepithelial cells as in theproximal tubules (kidney)or in lining of so calledstriated ducts in somesalivary glands.Specific for an intesiveIon transport (energyneeded) by e.g. Na+, K+ ATP-ase asan integral protein of the plasma membrane
Stevens, Lowe: Histology, 1993
Stevens, Lowe: Histology, 1993Ross, Pawlina: Histology, 2006