Last unit Flashcards
_____ _______ occurs whenever cells touch appropriate substrata
cell adhesion
In epithelia, cells form specialized, morphologically distinct devices called _______ ________
intercellular junctions
Four major classes of molecules in the ECF
- glycosaminoglycans (GAGs), usually linked covalently to proteins to form proteoglycans;
- fibrous proteins, such as collagen and elastin;
- multidomain adapter proteins, such as fibronectin and laminin;
- water and many solutes.
glycosaminoglycans (GAGs) are usually linked covalently to proteins to form _________
proteoglycans
elastin and collagen are examples of
fibrous proteins
Fibronectin and laminin are examples of
multidomain adapter protiens
The proteoglycan molecules form a highly ________ ___ in which the fibrous and multidomain proteins are embedded
hydrated gel
Two of the basal lamina’s characteristic components are:
collagen IV and laminin
GAGs consist of unbranched ________ chains composed of ________ repeats.
polysaccharide, disaccharide
Sulfation and carboxyl groups convey to the GAGs a high negative charge and, thus, the capacity to become _____ ______
highly hydrated
Glucosamines typically bind to specific proteins, with the exception of ______ ______
hylaluronic acid
purposes of GAGs
- create hydrogel in ECM
- Maintain gradients of different signaling morphogens
- Cell adhesion
- Preventing liquid leakage between high and low pressure environments
proteoglycans are covalently linked complexes of _____ and _______, typically of very high molecular weight.
GAGs and protein
_____ ______ are the most abundant proteins in mammals (about 25% of protein mass)
fibrous proteins
Which type of collagen is the most common form, abundant in connective tissues?
Collagen I
Which type of collagen is characteristic of the basal lamina
Collagen IV
Fibronectin
Component of ECM:large, dimeric glycoprotein whose two large subunits are linked together by disulfide bonds. Each subunit is folded into a series of functionally distinct binding domains.
Laminin
very large protein, composed of three subunits (α,β,γ) that form an asymmetric, disulfide-linked cross with the longer arm formed by a helical structure containing long stretches of all three subunits. Laminin is found in the basal lamina only (hence its name).
Cadherins
single-pass transmembrane glycoproteins that operate as homodimers. They are very common in intercellular junctional complexes. Must be anchored to actin cytoskeleton
Integrins
These are the “classic” adhesion molecules interacting with the ECM. Thus, their binding is heterophilic. Integrins are composed of α/β heterodimers. Many different α and β sub-units exist (both are transmembrane glycoproteins). They are mixed and matched to some degree.
What accounts for the large variety of integrins?
Since both subunits participate in ligand binding, this results in a large variety of integrins with distinct binding selectivities
CAMs
proteins located on the cell surface involved in binding with other cells or with (ECM) in cell adhesion.
Structure of CAMs
an intracellular domain that interacts with the cytoskeleton, a transmembrane domain, and an extracellular IgG like domain that interacts with other CAMs
Signaling molecules can be ________ by cell-cell adhesion
activated
endosymbiont hypothesis
the inner mitochondria membrane is derived from bacteria, while the outer membrane would be derived from eukaryotic cell.
Comment on the permeability of the mitochondrial membranes
The outer membrane is semi-permeable. The inner membrane is much less-permeable and contains most of the machinery required for oxidative phsophorylation
cristae
area of inner membrane with large number of infoldings
Mitochondrial matrix
The central space of mitochondria
TOM (translocase of outer membrane) and TIM (translocase of inner membrane) complexes
Import mitochondrial proteins into the mitochondria after they are synthesized in cytosol
Mitochondria are very dynamic organelles that undergo constant ____ and ____.
fusion and fission
Fusion plays a key role in:
repairing damaged mitochondria
Fission is required for
mitophagy
cellular GTPases for fusion
Mfn and OPA1
Cellular GTPases for fission
Fis1 and Drp
Most of the free energy released during oxidation of glucose is retained in the:
reducing coenzymes such as NADH
Electron transport across the inner membrane generates
a proton concentration gradient, electric potential
ATP synthase consists from two main parts:
F1 and F0.
F0 protein complex of ATP synthase
spans the inner mitochondria membrane and forms a proton channel.F0 uses the energy of proton movement through the channel to generate ATP.
How many protons are needed to generate 1 ATP molecule in ATP synthase?
3
Once made, ATP is transported out of mitochondria via the—–
ATP-ADP antiporter
Release of cytochrome c from the mitochondria depends on
Bak/Bax-dependent permeabilization of outer mitochondria membrane
apoptosome
Cytochrome c bound to several cytpolasmic proteins forming protein complex
Apoptosome activates ______, thus intiating apoptosis
caspases
When/why might ATP synthase become an ATPase
in the absence of proton gradient, ATP synthase is converted into ATPase, thus using up available ATP. That leads to ATP depletion and necrosis.
Damaged mitochondria are incapable of producing ATP, and also generate excessive amounts of:
reactive oxygen (ROS)
mitochondrial proteases responsible for recognizing and degrading misfolded proteins
mAAA, iAAA and Lon
Regulation of mitochondrial quality
- mitochondrial proteases mAAA, iAAA and Lon recognize and degrade misfolded proteins.
- damaged mitochondria can be “fixed” by fusing with healthy mitochondria, or eliminated by mitophagy.
- If mitochondria damage is extensive, mitochondria induces apoptotic cell death
hereditary spastic paraplegia
caused by a Mutation in mAAA protease, no quality control of misfolded proteins so they aggregate and cause ROS which kill neurons
Byproducts of glycolysis
2ATP, 2NADH, Pyruvate
Products of the TCA cycle
4 NADH, 1 FADH, Acetyl CoA
of H+ pumped across membrane per NADH
3 H+
What degrades misfolded proteins in the outer membrane of the mitochondria?
Proteosome, as usual
What degrades misfolded proteins in the inner membrane of the mitochondria?
mAAA
What recognizes and degrades misfolded proteins in the matrix?
Lon
Parts of ATP synthase
H+ channel, globular head (alternates alpha and beta subunits) and a shaft that secures the head
Steps of ATPase action (conformational changes)
1) binds ADP and Pi
2) Brings them together to make ATP
3) Affinity for ATP decreases, releases it
2 times when a cell can “decide to die” or not
1) Bax/Bac-if they get apoptotic signal they oligimerize and form channel so that cyt c leaks out
2) If cyt c is reduced at the last minute, cell will survive
ketoconazole
anti fungal drug but used in prostate cancer because it suppresses the adrenal glands, and therefore a circulating source of testosterone
Structural parts of the androgen receptor
- N terminus transactivation domain (NTD)
- DNA binding domain (DBD)
- Hinge region
- C-terminus ligand binding domain (LBD
Androgen receptor mechanism
The AR resides in the cytoplasm when not associated with an androgen
Testosterone is the most common androgen
Upon ligand binding inhibitory chaperones are dissociated and AR moves to the nucleus
AR undergoes homo-dimerization and binds to the androgen-responsive elements of the DNA
After binding, AR recruits co-activators and gene expression occurs.
Sources of testosterone
Testis – 90-95% of systemic testosterone
Adrenal glands 5-10% of systemic testosterone
Intracrine androgen production in the prostate cancer cells themselves
Ways to reduce testosterone
1) Surgical orchiectomy or medical castration
2) Block receptor activity with an anti-androgen (e.g. bicalutamide)
Mechanisms of resistance to hormone therapy in PCA
- AR activation via non-gonadal testosterone (most common)
- Overexpression of AR
- AR mutation leading to promiscuous AR activation
- Truncated form of AR, with constitutive activation of the ligand binding domain
Abiraterone
potent inhibitor of CYP 17 that blocks testosterone production from all 3 sources
Main side effects of Abiraterone
Excess of mineral corticoid, causing:
Hypokalemia
Edema
Hypertension
Enzalutamide (MDV3100)
antiandrogen drug
Mechanism of action of Enzalutamide
Blocks testosterone binding
Inhibits nuclear translocation
Inhibits Co-activator recruitment
Inhibits DNA binding of AR
Benefits of Enzalutamide over old therapy (bicalutamide)
5-8X stronger binding
No known partial agonist properties like biclutamide
Does Enzalutamide reduce the levels of testosterone?
No, it inhibits receptor activity
Epithelia function
- Protection
- Selective transport
- Biochemical modification of molecules (e.g. liver detoxifies)
- Communication (i.e. olfaction, taste, etc)
endothelium
A tissue that faces blood and lymph
mesothelium
the sheets of cells that line the enclosed internal spaces of the body cavities
The surface layer of all mucosae is an _______
epithelium
Which germ layer is epithelium derived from?
all 3!
mucosae
moist internal linings (mouth, nose, throat, GI tract, reproductive systems, etc.) that separate “outside” from “inside”
submucosa
deeper CT tissue
Most common CF mutation
F508del, although 1500 disease causing mutations are known
Typical features of CF
- Greasy, bulky, malodorous stools;
- failure to thrive due to exocrine pancreatic insufficiency
- Recurrent respiratory infections with opportunistic bacteria (e.g. Staphylococcus aureus, Pseudomonas aeruginosa and Burkholderia cepacia)
- Chronic sinus infections
- Digital clubbing on examination.
- Bronchiectasis
- Sweat chloride > 60 mmol/L.
most common presentation of CF
failure to thrive
What causes “failure to thrive” in CF patients
Children don’t gain weight despite good appetite and have frequent, bulky, foul-smelling, oily stools. A result of exocrine pancreatic insufficiency, the failure of the pancreas to produce sufficient digestive enzymes to break down and absorb fats and protein. Pancreatic insufficiency occurs in > 85% of persons with CF.
Infants with undiagnosed CF may also present with :
- hypoproteinemia with or without edema,
- anemia
- deficiency of the fat-soluble vitamins A, D, E, and K, because of ongoing steatorrhea
Other findings that should prompt a diagnostic evaluation for CF include:
bronchiectasis, rectal prolapse, nasal polyps, chronic sinusitis, and unexplained pancreatitis or cirrhosis
What GI issue present at birth might indicate CF?
Meconium ileus, a severe intestinal obstruction resulting from inspissation of tenacious meconium in the terminal ileum. Approximately 15% of newborns with CF present at birth with meconium ileus
Respiratory clinical manifestations of CF
productive cough, wheezing, chronic bronchitis and recurrent pneumonias, progressive obstructive airways disease, exercise intolerance, dyspnea, and hemoptysis. Chronic airway infection with bacteria
The predominant pathogen present in CF patients with infection
Pseudomonas aeruginosa
Infection associated with rapid decline in pulmonary function in CF patients
characteristic mucoid Pseudomonas
An acute change in respiratory signs and symptoms from the subject’s baseline is generically termed a ________ _________.
pulmonary exacerbation
Clinically, a CF exacerbation is typically manifested by:
increased cough and sputum production, decreased exercise tolerance, malaise, and anorexia
Symptoms of a CF exacerbation are typically associated with what?
decreased measures of lung function, new chest radiographic findings, or both.
Treatment for pulmonary exacerbations generally consists of:
antibiotics and augmented airway clearance and often requires hospitalization for 1-2 weeks.
CF is a syndrome of chronic _____ _______, malabsorption and _______ ________
sinopulmonary infections, nutritional abnormalities
Median predicted survival age for CF
37
Sinus symptoms in CF patients
sinusitis, nasal polyps
Lung dysfunction in CF
Endobronchitis, bronchiectasis
Pancreas dysfunction in CF
exocrine insufficiency, CF related diabetes
Intestinal dysfunction in CF
meconium ileus, constipation
Liver dysfunction in CF
Focal sclerosis
Reproductive implications of CF
Vas deferens doesn’t develop in males, functionally infertile but can still father children
Where is the CF gene located and how large is it?
Large gene of 250,000 base pairs with 27 exons
located on chromosome 7
At what stage of molecular processing does the DF508 mutation cause problems?
AA deletion, blocks protein processing
End stage CF is characterized by:
Bronchiectasis
Infection
Inflammation
Mucus Plugging
The CTFR protein is a member of the ____________ superfamily
ATP-binding cassette (ABC)
CTFR protein structure
2 six membrane spanning domains (MSD)
2 nucleotide-binding domains (NBD)
Unique, highly charged regulatory (R) domain
Because CL- can not exit the cell but Na+ (and with it water) continue to enter the cell, what happens?
The mucous layer is excessively sticky and it depletes the pericilliary layer
Criteria for diagnosis of CF
Positive NBS OR
>1 clinical feature of CF OR
Family h/o CF
+
Sweat chloride 60 mmol/L &/OR
2 CF mutations
Typical treatment for CF
- Pancreatic enzymes,
- vitamins (problems digesting fat soluble vitamins), -salt
- Vit. E (deficiency=cognitive problem)
- Vest to break up mucus, Huff coughs to cough up mucus
- Inhaled medicine to break up mucus
- Antibiotics because bacteria get trapped
Ivacaftor
CFTR potentiator, Only approved for patients with at least one G551D mutation (4% of CF patients)
Epithelial tumor is called a ______
carcinoma
What value indicates a sweat test positive for CF?
Cl- > 60 mmol/L is diagnostic for cystic fibrosis
Characteristics of epithelial stem cells
1) Capacity for self-renewal
2) Capacity for cell division
3) Generates cells that differentiate and become specified
4) Tightly regulated
Stem cell lineage
Stem cell, its intermediate progeny, and all of the differentiated progeny it makes
Transit amplifying cells
transitional intermediates: daughters that also proliferate themselves (undergo cell division cycles), often at faster rates
Main developmental signaling pathways
Wnt, sonic hedgehog, notch, FGF(RTKs), TGFB
Gland
an elaboration of epithelial sheets that exists for specific secretion
Exocrine glands
secrete on the surface of epithelial sheets and secrete from the APICAL membrane
Endocrine glands
Secrete hormones into blood and work at long distances, Secrete final product from the BASOLATERAL membrane
2 general classes of secretions
Mucous and serous (watery:sweat)
Goblet cells
single cell that creates mucous of the gut (a single-cell exocrine gland)
Acini
A cluster of cells that resembles a “berry,” the berry-shaped termination of an exocrine gland, where the secretion is produced
Simple epithelia
one sheet of cells, one side faces the space and the other the connective tissue
Stratified epithelia
multiple layers of cells, layers of cells do not attach to the basal lamina (not every cell touches the basal lamina)
Transitional epithelium
found in the bladder. Stratified but when it is stretched they form a single sheet
Polarization of epithelial cells
Apical vs basolateral
also internally polarized (secretory vessels and cytoskeleton, for example)
Transcytosis
endocytosis–> crossing of cell–> exocytosis without stopping at the ER or golgi
Claudins
The most important components of the tight junctions, proteins that establish the paracellular barrier that controls the flow of molecules in the intercellular space between the cells of an epithelium
Desmosomes
A cell-to-cell adhesion structure localized on the LATERAL sides of plasma membranes.
Desmosomes help to resist shearing forces. Contain cadherins that attach to intermediate filaments