TIROSIN CHINASI
CITOPLASMATICHE
TIROSIN CHINASI CITOPLASMATICHE
PH
SH3
KINASE DOMAIN
SH2
Tec (Btk/Itk/Bmx)
FAK/Pyk2
KINASE DOMAIN
Focal adhesion targeting (paxillin binding)
(FERM)
KINASE DOMAIN
SH2
Ac. miristico/palmitico
Ac. miristico
SH3
SH2
SH2
SH2
SH3
SH2
KINASE DOMAIN
KINASE DOMAIN
KINASE DOMAIN
KINASE DOMAIN
Jak
Src
(Blk, Lck, Lyn, Fyn, Fgr, Hck, Yes)
ZAP70/Syk
Abl/Arg
G. Steven Martin : THE HUNTING OF THE SRC, Nature Reviews Molecular Cell Biology 2, 467-475 (2001)
Integrine
Src
FAK e membri della famiglia del Src costituiscono un’unità di trasduzione del segnale da parte
di molecole adesive definite INTEGRINE
SH3
SH3
YP397
SH2
Src
SH1
SH2
Src
SH1
Outside-in signaling
FAK
Autofosforilazione
Interazioni con altre proteine
(Src, PI3 chinasi, PLCg)
Sito di interazione con Grb2
SH2
SH2
YP
F1
F2
dominio FERM
F3
YP
dominio catalitico
dominio FAT
C
N
Poli-P
Interazione con catena b delle integrine
e fattori di crescita
Interazione con fosfatidil inositolo (4,5)
bisfosfato (PIP2)
Interazione con proteine favorenti la
polimerizzazione dell’actina (complesso Arp
2/3)
SH3
Interazione con Cas
Interazione con paxillina
Anche FAK come Src viene attivata in seguito alla rottura di interazioni intermolecolari che
la mantengono in uno stato inibito.
Il distacco da proteine della matrice extracellulare induce una forma di apoptosi (chiamata “anoikis”)
che determina il fenomeno della cosiddetta “crescita dipendente dall’ancoraggio”
SH3
YP397
AKT
PI3K
PROLIFERAZIONE E
SOPRAVVIVENZA
SH2
Src
PY
Fosfatidilinositolo 4,5 fosfato
P P
P
Fosfatidilinositolo 3,4,5 fosfato
P
IP3
P P P P P P
SH3
YP397
PIP5-chinasi g
SH2
Src
PLCg
PI3-chinasi
GEFs
SH1
Poli-P
Crk
PY
PY
PY
Dock180
Cas
PH
paxillina
YP925
Grb2
Rac, Cdc42
Poli-P
Sos
Rac
Ras
PAK
Polimerizzazione dell ’actina
e protrusione del lamellopodio
JNK
Interazione con altre
Proteine citoscheletriche e segnalanti
Raf
MAPK
MAPK (ERK1/2)
Movimento cellulare
Proliferazione e sopravvivenza cellulare
TRASCRIZIONE GENICA
FAK, Src e altre chinasi vengono inibite da tirosin fosfatasi che sono sensibili all’azione
inibitoria di ROIs
FAK, Src, GF-Rs,
MAP chinasi (JNK, ERKs)
inattive
FAK, Src, GF-Rs,
MAP chinasi (JNK, ERKs)
attive
Protein fosfatasi
attiva
Protein fosfatasi
inattiva
La transizione epitelio-mesenchimale rappresenta una modificazione tipica dei tumori epiteliali
metastatici
An epithelial-mesenchymal transition (EMT) is a biologic process that allows a polarized epithelial cell, which normally
interacts with basement membrane via its basal surface, to undergo multiple biochemical changes that enable it to
assume a mesenchymal cell phenotype, which includes enhanced migratory capacity, invasiveness, elevated resistance
to apoptosis, and greatly increased production of ECM components .
The completion of an EMT is signaled by the degradation of underlying basement membrane and the formation of a
mesenchymal cell that can migrate away from the epithelial layer in which it originated. (Kalluri and Weinberg, J. Clin.
Invest. 119:1420, 2009)
EPITHELIAL-MESENCHIMAL TRANSITION
MESENCHIMAL-EPITHELIAL TRANSITION
giunzioni serrate (tight junction)
F-actina
microtubuli
Previene endocitosi e degradazione E- caderina
giunzioni aderenti (adherens junctions)
E-caderina
E-caderina
b cat.
Rac
a cat.
Rho
Movimento
F-actina
b cat.
Migrazione nel nucleo e trascrizione geni
implicati nella proliferazione cellulare
L’aumentata stimolazione con fattori di crescita altera funzioni di E-caderine
In diversi modi
giunzioni serrate (tight junction)
F-actina
giunzioni aderenti (adherens junctions)
E-caderina
b cat.
a cat.
F-actina
Recettori per fattori di crescita:
TGFbRI e II, IGF-1R, EGFR, c-Met
L’aumentata stimolazione con fattori di crescita altera funzioni di E-caderine
In diversi modi
1.
Il promotore del gene per le E-caderine viene represso da repressori trascrizionali
(Snail, Twist, Slug e altri) indotti da Recettori per GF e altre vie attivate nel corso di “progressione”
tumorale (compreso Nf-kB).
2. Tirosin chinasi recettoriali (EGFR, IGF-1R, c-Met, FGF) e non recettoriali (c-Src) inducono
fosforilazione e successiva ubiquitinilazione di E-caderine e catenina con conseguente degradazione
nel proteosoma. La fosforilazione di E-caderina comporta anche il distacco di a e b catenine.
3. Proteasi (metallo-proteasi – MMP) proteolizzano E-caderine alterando contatti cellula-cellula.
4. Gli stessi segnali che “down-regolano” espressione di E-caderine aumentano espressione di Ncaderine (il cosiddetto “caderin-switch”), che sono espresse da cellule mesenchimali e regolano
positivamente il movimento cellulare.
movimento
Sress fibers, focal adhesion
Rac
Cdc42
Rho
E-caderina
b cat.
a cat.
F-actina
Inibizione di GSK da parte di GF-Rs o altri stimoli favorisce la progressione neoplastica
P
Snail
P
b cat.
E-caderina
GSK-3
b cat.
P
PP
Repressione sintesi E-caderine
Trascrizione geni implicati in proliferazione e progressione
NUCLEO
DEGRADAZIONE
Un meccanismo aggiuntivo di regolazione della funzione di bcatenica è rappresentato da un suo aumento di
espressione in cellule stimolate con proteine wnt (ampia famiglia di fattori di crescita poco caratterizzati)
Gene onco-soppressore, la cui
mutazione in cellule della linea
germinale determina la
Poliposi Adenomatosa Famigliare
del Colon
a | In the absence of WNT signalling, -catenin levels in the cytoplasm and nucleus are low as a result of continuous
phosphorylation by the serine/threonine kinases CK1 (casein kinase 1) and GSK3 (glycogen synthase kinase 3), leading to
binding of -transducin-repeat-containing protein (TRCP) and to ubiquitylation and degradation by the proteasome. The
destruction complex is composed of CK1 and GSK3, as well as the anchor proteins AXIN1 (axis inhibition protein 1 ) and
APC (adenomatous polyposis coli). In the nucleus, TCF (T-cell factor) molecules are bound by co-repressors such as
GRG/TLE (Groucho/transducin-like enhancer) proteins that shut off expression of WNT target genes. Other components
of the repressor complex include CTbP (C-terminal binding protein) and HDACs (histone deacetylases). -catenin in the
nucleus is inhibited from binding TCF by ICAT (cell autonomous inhibitor of -catenin and TCF) . The Frizzled receptor
complex — composed of Frizzled and LRP5 (LDL-receptor-related protein 5) or LRP6 — can also be actively inhibited by
receptor-bound soluble inhibitors such as DKK1 (Dickkopf homologue 1). b | Upon binding of a lipid-modified WNT
protein to the receptor complex, a signalling cascade is initiated. LRP is phosphorylated by CK1 and GSK3, and AXIN1 is
recruited to the plasma membrane. The kinases in the -catenin destruction complex are inactivated and -catenin
translocates to the nucleus to form an active transcription factor complex with TCF, leading to transcription of a large set
of target genes. In the nucleus, -catenin binds to TCF and LEF factors and recruits co-factors such as legless (LGS; also
known as BCL9) and Pygopus (PYGO), CBP/p300, Brahma and MED12 to initiate transcription99, 100, 101. DVL,
mammalian homologue of Drosophila Dishevelled; PP2A, protein phosphatase 2A.
WNT PROTEINS POSSONO ANCHE ATTIVARE RHO GTPASI E SEGNALI CALCIO
a | Planar cell polarity (PCP) signalling does not involve -catenin, LRP (LDL-receptorrelated protein) or TCF (T-cell factor) molecules, but leads to the activation of the small
GTPases RHOA (RAS homologue gene-family member A) and RAC1, which activate the
stress kinase JNK (Jun N-terminal kinase) and ROCK (RHO-associated coiled-coilcontaining protein kinase 1) and leads to remodelling of the cytoskeleton and changes
in cell adhesion and motility. Through largely unknown mechanisms, canonical -catenin
signalling can be inhibited by the PCP pathway. b | WNT–Ca2+ signalling is mediated
through G proteins and phospholipases and leads to transient increases in cytoplasmic
free calcium that subsequently activate the kinases PKC (protein kinase C) and CAMKII
(calcium calmodulin mediated kinase II) and the phosphatase calcineurin. The
activation of PLC (phospholipase C) by DVL (mammalian homologue of Drosophila
Dishevelled) leads to the cleavage of PtdIns(4,5)P2 (phosphatidylinositol-4,5bisphosphate) into InsP3 (inositol trisphosphate) and DAG (diacylglycerol). DAG,
together with calcium, activates PKC, whereas InsP3 binding to receptors on the
membranes of intracellular calcium stores leads to a transient increase in cytoplasmic
free calcium, often also triggering an increase from extracellular stores. AP1, activator
protein 1; CDC42, cell-division cycle 42; DAAM, Dishevelled-associated activator of
morphogenesis; NFAT, nuclear factor of activated T cells; PDE6, phosphodiesterase 6.
Dipartimento di Patologia
Sezione di Patologia Generale
Università di Verona
Granulocyte/macrophage progenitors
Megakaryocyte/erythrocyte progenitors
Common myeloid progenitors
Haematopoietic stem cell
Chronic myeloid leukemia-blast phase (70%)
Common lymphoid progenitors
Chronic myeloid leukemia-blast phase
(30%)
Chronic myeloid leukemia-chronic phase
R. Ren, 5:172-183
Weisberg et al. 7:345, 2007
With the aid of several mediator proteins, BCR-ABL associates with Ras and stimulates its activation. The adaptor protein, growth factor receptor-bound protein 2
(GRB2), interacts with BCR-ABL through the proximal SRC homology 2 (SH2)-binding site that develops when the tyrosine 177 (Y177) residue of BCR-ABL is
autophosphorylated. GRB2, when bound to BCR-ABL, interacts with the son of sevenless (SOS) protein. The resulting BCR–ABL–GRB2–SOS protein complex activates
Ras. The adaptor proteins CRKL (CRK-like) and SHC (SH2-containing protein) can also mediate the BCR-ABL activation of Ras. Ras and the mitogen activated protein
kinase (MAPK) pathway are coupled by Raf (a serine/threonine kinase). Raf catalyses the phosphorylation of the mitogen-activated and extracellular-signal regulated
kinase kinases 1 and 2 (MEK1 and MEK2); this results in their activation. Through the stimulation of the Ras–Raf pathway, BCR-ABL increases growth factorindependent cell growth. BCR-ABL also associates with and activates the phosphatidylinositol-3 kinase (PI3K) pathway, suppressing programmed cell death and
increasing cell survival. BCR-ABL is associated with components of the focal adhesion(that is, actin, paxillin and focal adhesion kinase, or FAK); the activation of CRKL–
FAK–PYK2 leads to a decrease in cell adhesion. BCR-ABL also associates with the Janus kinase and signal transducer and activator of transcription (JAK–STAT)
pathway. Finally, BCR-ABL activates pathways that lead to atypical responses to chemotactic factors, which leads to an increase in cell migration. BCR-ABL also
associates with survival proteins that interact with the mitochondrial-based BCL2 family. CAS, p130 CRK-associated substrate; GAB2, GRB2-associated binding protein
2; SHIP, SH2-containing inositol-5-phosphatase
(Imatinib mesilato)
Figure 1.6
Copyright © 2011 Academic Press Inc.
Esempi di difese locali
Figure 3.1
Copyright © 2011 Academic Press Inc.
Figure 1.2
Copyright © 2011 Academic Press Inc.
NECROSI
DAMP: Damage associated molecular pattern
Pattern recognition receptors
Pathogen associated molecular pattern Figure 1.3
Copyright © 2011 Academic Press Inc.
Figure 1.4
Copyright © 2011 Academic Press Inc.
TRASDUZIONE DEL SEGNALE DA PARTE DI RECETTORI IMMUNI
ITAM (Immunoreceptor tyrosine-based inhibitory motif) : DExxYxxL/I(x)6-7YxxL/I
FcgRIIA
ITAM
FcgRIIB
ITIM: I/VxxYxxL/V
Immunoreceptor tyrosine-based inhibitory motif
TRASDUZIONE DEL SEGNALE DA PARTE DI RECETTORI IMMUNI
attivazione
C-type lectins
Lyn
Fyn/ Lck
ZAP70
Lyn
Syk
Syk
Lyn/Hck/Fgr
Syk
Syk
Abl
Lipide fosfatasi
Protein fosfatasi
ANCHE ALCUNE FAMIGLIE DI INTEGRINE (b2 E b3) TRASDUCONO IL SEGNALE
MEDIANTE UN MODULO BASATO SU ADATTATORI CON SEQUENZA ITAM E SYK
ITAM
?
YP
YP
SYK
SFK