Download Lecture 8 Intermediate filaments

Lecture 8
Intermediate filaments
Microfilaments
(actin filaments):
5-9 nm
Microtubules:
25 nm
Intermediate
filaments:
10 nm
Intermediate filaments
Ishikawa, H., Bischoff, R. & Holtzer, H. (1968). Mitosis and intermediate filamentsized filaments in developing skeletal muscle. J. Cell Biol. 38, 538–555.
Intermediate filaments
Intermediate filaments
in the cytoplasm of the mammalian cell
20 µm
IF in a glial cell
Filaments of fibrillary acidic protein
100 µm
Two types of intermediate filaments in cells of
the nervous system
Neurofilaments in
a nerve cell axon
Glial filaments in
glial cells
Cross-section of
an axon showing
both MT and IF
IF anchored to desmosomes and hemidesmosomes
Extracellular
matrix
Plectin cross-links IF to microfilaments and MT
IF organization in metazoan cells
Herrman et al. (2007). Nat. Rev. Mol. Cell. Biol. 8: 562-573
Demonstration of mechanical connections
between extracellular matrix and nucleoplasm
“Harpooning” of the cell
by a micropipette
Maniotis et al. (1997). Proc. Natl Acad. Sci. USA 94, 849–854.
>65 genes encoding IF proteins in humans
Tissue-specific expression of IF
IFs in tumor diagnostics
Components of IFs (in contrast to MF and MT)
are not globular proteins
Levels of organization and assembly of IF
A model of intermediate filament construction
A model of intermediate filament assembly
ULF= unit-length filaments
Krimse et al. (2007). A Quantitative Kinetic Model for the in Vitro Assembly of
Intermediate Filaments from Tetrameric Vimentin. J. Biol. Chem. 282, 18563-18572.
IF assembly in vivo
Cell
fusion
A model of intermediate filament construction
Coiled-coil structure is an ubiquitous feature
of intermediate filaments
Coiled-coil structure is an ubiquitous feature
of intermediate filaments
a,d: small apolar residues
(Leu, Ile, Met, Val)
Structural model of cytoplasmic and nuclear
intermediate filament protein dimers
Herrman et al. (2007). Nat. Rev. Mol. Cell. Biol. 8: 562-573
Francis Crick: Discoverer of the genetic code
(Matt Ridley, 2006, HarperCollins)
In the […] laboratory he took charge of making sure that everybody knew about
everyone else’s scientific work. […] ‘Crick week’ was a week of seminars when
the lab members told each other about their results. Sitting at the front, Crick was a
terrifying presence, concentrating hard, interrupting frequently, and of course at the
end giving a licid summary of not only what the speaker had just said but what they
should have said and what it all meant. […] Even those asking questions were
sometimes corrected: “The question you should have asked is … and the answer is
…”. Graeme Mitchison recalls that, as a result, the seminars were both a terrifying
ordeal, and an excellent spectator sport.
Major types of IF in vertebrate cells
TYPES OF IF
COMPONENT POLYPEPTIDES
LOCALIZATION
Nuclear
Lamins A, B, and C
Nuclear lamina (inner lining
of nuclear envelope)
Vimentin-like
Vimentin
Many cells of mesenchymal
origin
Desmin
Muscle
Glial fibrillary acidic protein
Glial cells
Peripherin
Some neurons
Type I keratins (acidic)
Epithelial cells and their
derivatives (e.g., hair and
nails)
Epithelial
Type II keratins (basic)
Axonal
Neurofilament proteins (NF-L,
NF-M, and NF-H)
Nuclear lamina (inner lining
of nuclear envelope)
The domain organization of intermediate
filament protein monomers
Heterooligomeric character of IFs is a basis of
intra- and interfilament heterogeneity
A strong filament formed from elongated fibrous
subunits with strong lateral contacts
Atomic Force Microscopy as a tool for biology
Herrman et al. (2007). Nat. Rev. Mol. Cell. Biol. 8: 562-573
Mechanical properties of actin, tubulin,
and vimentin polymers
Dynamic nature of IF within a cell –
FRAP technique
http://www.ibiology.org/ibioseminars/cell-biology/robert-goldman-part-1.html
Bob Goldman on IF (iBiology.org)
http://www.ibiology.org/ibioseminars/cell-biology/robert-goldman-part-1.html
Lev Sergejevič Teremin (1896-1993)
What regulates a stability of
intermediate filaments?
The nuclear lamina is composed of a
special class of IF
Gerace, L., Blum, A. & Blobel, G. (1978). Immunocytochemical localization of the
major polypeptides of the nuclear pore complex-lamina fraction. J. Cell Biol. 79,
546–566
Gerace, L. & Blobel, G. (1980). The nuclear envelope lamina is reversibly
depolymerized during mitosis. Cell 19, 277–287. The nuclear lamina
The nuclear lamina
Nuclear pore
complex
CYTOSOL
Nuclear envelope
Nuclear lamina
Chromatin
NUCLEUS
The nuclear lamina
1 µm
nuclear lamina in a frog oocyte
Disassembly of nuclear lamina in prophase is
driven by phoshorylation of lamins by Cdk2p
>230 mutations in lamin A cause a complex set
of at least 13 different human diseases
Hutchinson-Gilford progeria
atypical Werner syndrome
muscular dystrophies
cardiomyopathy
http://www.cell.com/abstract/S0092-8674(12)00401-1
Hutchinson-Gilford progeria is caused by deletion in lamin A gene
leading to aberant processing of the protein
Coutinho et al. (2009). Immunity & Ageing 6:4
Participation of lamin B in the organization
of spindle pole
Lamins A & C: present primarily in differentiated cells
Lamin B: essential for cell survival
RNAi-mediated reduction of lamin B in C. elegans and HeLa
cells: spindle defects & chromosome mis-segregation
Ma et al. (2009). Requirement for Nudel and dynein for assembly of the
lamin B spindle matrix Nat. Cell Biol. 11: 247-256
Nuclear lamina is important for recruitment of defined
chromosomal regions and participates in gene
regulation
Disturbance of association of chromosomes with
nuclear lamina in cells from Down syndrome patients
may cause a transcriptome-wide effects
Pope & Gilbert (2014). Nature 508: 323-324.
Letourneau et al. (2014). Nature 508: 345-350.
Keratin filaments join cells together in cell sheets
Keratin-green; Desmosomes-blue
Different keratins are present
in different skin layers
Blistering of the skin caused
by a mutant keratin gene
basal cell of epidermis
basal lamina
defective keratin
network
hemidesmosome
40 µm
Wild-type mouse
Mouse expressing
abnormal keratin
J. Cell Biol. 115: 1661-1674 (1991)
Epidermolysis bullosa hereditaria simplex
Coulombe, P. A. et al. (1991). Point mutations in human keratin 14 genes of
epidermolysis bullosa simplex patients: genetic and functional analyses. Cell
66, 1301–1311
Alexander disease: autosomal-dominant
neurodegenerative disorder caused by
mutations in the gene for glial fibrillary
acidic protein (GFAP)
Desmin filaments in muscle
Destruction of muscle architecture
in desminopathy (muscular dystrophies
and/or cardiomyopathies)
Desmin aggregates
(red) in myofibres
Skeletal muscle from
a patient
(left: massive accumulation
of granulofilamentous
material)
Herrman et al. (2007). Nat. Rev. Mol. Cell. Biol. 8: 562-573
The assembly and decay of desmin mutants
WT desmin
mutant desmins
Herrman et al. (2007). Nat. Rev. Mol. Cell. Biol. 8: 562-573