#1 Cell Biology
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1
The human body contains ___ different cell types
~300 different cell types
2
Progeria is
a genetic disease in which patients age so rapidly they die in their second decade of life (early teens -to-> early 20's)
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How do patients with progeria die
from advanced atherosclerosis (a disease which typically effects the elderly)
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How common is progeria
Very rare disease- less than 300 cases world-wide and less than 200 cases in U.S.A.
5
What is atherosclerosis
a cardiovascular disease
the thickening or hardening of arteries by a build up of plaque on inner lining of artery
the thickening or hardening of arteries by a build up of plaque on inner lining of artery
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The nucleus is surrounded by a double bounded (inner and outer membrane) called the
Nuclear envelope
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Cell images that have alot of endoplasmic reticulum tell us what
Cell makes alot of protein
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the ___ lies directly underneith the inner nuclear membrane and forms a tough fibrous network
nuclear lamina
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Lamina means
a thin flat "layer" or membrane
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the ___ connects the nuclear membrane to chromatin inside the nucleus
nuclear lamina
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Where does the nuclear membrane come together with the cytoplasm
Nuclear pores
12
.
Nuclear lamina with envelope stripped away
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3 proteins that make up nuclear lamina
Nuclear Lamins A, B, & C
14
Nuclear lamina 2 functions
1) structural stability
2) important function in connecting/disconnecting the nuclear membrane from chromatin(depending on stage in cell cycle)
2) important function in connecting/disconnecting the nuclear membrane from chromatin(depending on stage in cell cycle)
15
Progeria is a defect in what gene
Defect in Lamin A protein gene
16
Laminopathy is a
group of genetic disorders caused by mutations in genes encoding proteins of the nuclear lamina
e.g. Progeria
e.g. Progeria
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2 stages of cell life
1) Interphase
2) Mitosis
2) Mitosis
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During interphase the lamins are all ___
Dephosphorylated
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Depohosphorylated lamins do what
dephosphorylated lamins nicely bind/connect
the nuclear membrane protein -to-> chromatin
the nuclear membrane protein -to-> chromatin
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During interphase the DNA is organized in
chromatin
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During mitosis the DNA is organized in
Chromsomes
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During interphase, when the nuclear envelope is intact, lamins are in the ___ state
Dephosphorylated state
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In early mitosis lamins are in a ___ state
Lamins are in a phosphorylated state
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In early mitosis lamins are phosphorylated by a
special kind of kinase
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In early mitosis the newly phosphorylated lamins cause ___ connection to break
the chromatin -to-> nuclear membrane connection to break
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The chromatin -to-> nuclear membrane connection to breaking begins
the process of nuclear membrane disassembly
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For mitosis to happen what must happen to the nuclear envelope
nuclear envelope must dissolve via the phosphorylation of lamins
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For mitosis to happen what must happen to the chromatin
must condense into chromosomes
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What is keeping the chromatin from condensing on their ownIn early
the nuclear lamina
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What happens to nuclear envelope after it is dissolved by dephosphorylation of lamins
Fragments stay in cell until mitosis is over
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phosphorylation of lamins -leads to->
condensatition of chromatin into condensed chromosomes
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dephosphorylation of lamins -leads to->
decondensatition of chromosomes into uncondensed chromatin
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Lamins are a type of ___ & responsible for ___
Lamins
-are a type of intermediate filament protein
-responsible for connecting chromatin to the inner nuclear membrane
-are a type of intermediate filament protein
-responsible for connecting chromatin to the inner nuclear membrane
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Late in mitosis(prophase) a ___ returns lamins to the dephosphorylated state
special type of phosphatase
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Late in mitosis(prophase) a phosphatase returns lamins to the ___ state
dephosphorylated state
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Lamins returning to the dephosphorylated state permits
the nuclear membrane assembly to occur
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the relationship/thought/cause of progeria and laminopathies to lamia
if you have a mutation that interferes with lamin function, it will not function properly during mitosis & if cells can't replenish/ regenerate/ renew themselves, laminopathy patients will age very rapidly
38
Hingontons disease is a genetic disorder in the
Huntingtin protein
39
What gene codes for the huntingtin protein
HTT gene
40
Huntington Disease genetic testing results
An abnormal amount(41) trinucleotide CAG repeats in the HTT gene
41
CAG codes for what amino acid
glutamine
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CAG repeats on HTT gene attack
Glutamine residues
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Huntington's disease is an example of which type of inheritence
Autosomal dominant
44
The # of nuclear pores on a cell nucleus is directly correlated with
Metabolic activity
45
(3)Examples of cells with high # of nuclear pores
Cells correlated with high metabolic activity:
1) Liver cells
2) Muscle cells
3) Fat cells
1) Liver cells
2) Muscle cells
3) Fat cells
46
Cell type with the lowest # of nuclear pores
Oocyte
-has almost 0 pores b/c its not metabolically active
*When recruited to be ovulated it becomes one of the most metabolically active cells (most nuclear pores)*
-has almost 0 pores b/c its not metabolically active
*When recruited to be ovulated it becomes one of the most metabolically active cells (most nuclear pores)*
47
All protein translation happens where
Cytoplasm
48
Proteins made in the cytoplasm destined to be used in nucleus get inside via
nuclear pores
49
Annukar term means
"Ring like"
50
Cargo greater than 5-10k Daltons must enter via
Active transport
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Cargo less than or equal to 5-10k Daltons must enter via
Simple diffusion
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When the central plug of the nuclear pore is open
Anything allowed into nucleus by active transport that is bigger than 10k Daltons or more
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When the central plug of the nuclear pore is closed
prevents anything bigger than 5-10k Daltons to enter
Anything less than or equal to 5-10k Daltons must enter via simple diffusion
Anything less than or equal to 5-10k Daltons must enter via simple diffusion
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What does NLS stand for
Nuclear Localization Signals
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NLS used for ___ recognized by ___
used for: attachment to proteins being made in the cytoplasm that need to enter the nucleus
recognized by: Importins
recognized by: Importins
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NLS signal is
5/6 basic amino acids
-Lys-Lys-Lys-Arg-Lys-
-Lys-Lys-Lys-Arg-Lys-
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Importin function
Importins recognize newly synthesized proteins with NLS signal & chaperone them to a nuclear pore
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Importins bind to ___ on cargo and escort cargo to ___
bind to NLS(Nuclear Localization Signals)
escort to a nuclear pore
escort to a nuclear pore
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What is happening in Huntington's disease
The mutant huntingtin protein is gedraded into small fragments <5kDa
These fragments enter nucleus via simple diffusion and "gum up the works"
These fragments enter nucleus via simple diffusion and "gum up the works"
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41 extra glutamine fragments do what to a mutant huntingtin protein
-Cause it to misfold
-Unable to be recognized by importins
-Gets recognized by another protein that chaperones it to the proteosome
-Unable to be recognized by importins
-Gets recognized by another protein that chaperones it to the proteosome
61
The proteosome is
Organelle of protein degregation in a cell
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What happens to a mutant huntingtin protein within a proteosome
-Gets degregated into smaller protein building blocks/fragments that are less than 5-10kDa
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The fragments of a degraded huntingtin protein do what
enter the nucleus via simple diffusion
these then "gum up the works"
these then "gum up the works"
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Proteins are all made in the ___
All made in cytoplasm
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Proteins are brought into nucleus through ___ via ___
nuclear pores via importins
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Proteins are taken out of nucleus through ___ via ___
nuclear pores via exportins
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Exportins help facilitate exiting of the nucleus by binding to proteins as well as ___
ribonuclear protein complexes
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What happens to cargo loaded on exportin in the cytoplasm
Cargo dissociates
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What happens to exportin after cargo dissociates in cytoplasm
Free exportin then returns through a nuclear pore
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There 6 different types of ___
Exportins
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There ___ different types of exportins
6
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What makes each of the 6 types of exportins unique
Each has its own particular subset of proteins it will bind to & export out of nucleus
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Which type of exportin is highly overexpressed in most cancer cells
Exportin-1
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What is the cargo set for Exportin-1
-Tumor Suppressors
-Other Antiproliferative molecules
-Other Antiproliferative molecules
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Where are tumor supressors & other antiproliferative molecules found
The nucleus
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Tumor supressors & other antiproliferative molecules function to do what in the nucleus
Bind to DNA & regulates transcription
(transcription that is needed to go through with the cell cycle)
(transcription that is needed to go through with the cell cycle)
77
What happens when you over express Exportin-1 (3 steps)
1st) You will over-shuttle these tumor suppressors & other antiproliferative molecules out of the nucleus to the cytoplasm
2nd) In the cytoplasm these tumor suppressors cannot work in the cytoplasm nucleus thinks it can divide b/c nothing is there to suppress/ regulate transcription
3rd) This will lead to tumor growth
2nd) In the cytoplasm these tumor suppressors cannot work in the cytoplasm nucleus thinks it can divide b/c nothing is there to suppress/ regulate transcription
3rd) This will lead to tumor growth
78
Exportin-1 has a subset of cargos that are almost exlusively ___
anti-proliferative
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What does SINE stand for
selective inhibitors of nuclear export
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What are SINEs
small molecules that block the catalytic pocket on Exportin-1
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Effect of SINEs
When they block the catalytic pocket on exportin-1, in turn, this keeps tumor suppressors in the nucleus
82
SINE acts as a ___ in the catalytic binding pocket of Exportin-1 so that ___ & the cell maintains ___
-an antagonist
-the tumor suppressors don't get shuttled out of the pocket
-cell maintains the ability to shut down proliferation
-the tumor suppressors don't get shuttled out of the pocket
-cell maintains the ability to shut down proliferation
83
When should SINEs be used
In cancer patients with highly overexpressed Exportin-1 complexes
-In combination with other cancer therapies
-tough to treat cancers
-In combination with other cancer therapies
-tough to treat cancers
84
What makes SINE therapy unique
Its mechanism is unlike any other cancer drug on the market
85
Proteins destined for export have ___
NES (Nuclear Export Signals)
86
Cancer cells that greatly over-express exportin-1 provide what to scientist
These cells provide a therapeutic target
87
Huntington's disease classified as
a "defective nuclear import" disease
*NOTE: NOT a defective nuclear pore*
*NOTE: NOT a defective nuclear pore*