Download Document

Genetics of Vascular Diseases
Jake Lusis
3-730 MRL
[email protected]
Carl Miller, ~1938, Oslo County Hospital, Norway
Inheritance of:
Cholesterol level (mg/dl):
330
210
Tendon xanthomas:
Early coronary artery disease (under 55 years of age):
210
410
490
200
460
210
190
180
420
430
Cosegregation of triad of xanthomas, high cholesterol
and early heart disease
Tendon Xanthomas
Inheritance of:
Cholesterol level (mg/dl):
210
230
Tendon xanthomas:
Early coronary artery disease (under 55 years of age):
190
400
210
210
430
420
170
420
810
490
180
420
This individual died from
severe CAD at age 7
Lecture delivered in Sweden Dec 9, 1985 when they
received the Nobel Prize in Physiology. Published in
Science, 232, 34-47, 1986
Experiments with 125I-LDL and skin fibroblasts
skin fibroblasts from normal and FH individuals
add labeled 125I-LDL ( )
incubate to allow binding
wash away unbound LDL and follow label
- 125I-LDL on surface can be displaced from cells by anionic polymers
- 125I-LDL that has been internalized cannot be displaced from cells
- 125I-LDL that has been degraded to amino acids is soluble in tricholoroacetic acid
Experiments with fibroblasts from normal and FH individuals
Normal
FH homozygote
Sequential steps in LDL receptor pathway: Discovery of
receptor mediated endocytosis
Degradation of LDL by lymphocytes and following injection
Cloning of the Human LDL Receptor
isolate plasma membrane
cultured skin fibroblasts
purify such that a single protein
remains upon electrophoresis
extract proteins with
detergent and subject to
chromatography
125I-LDL
bound
digest the protein and
sequence the resulting
peptides
-ASN-PHE-THR-SER-
based on the amino acid
sequence, synthesize
corresponding oligonucleotide
probes
….CACTCGACAGCGAAC...
probe cDNA and
genomic libraries.
Confirm identity of
clones by sequencing
and expression
studies
Domain structure of the LDL receptor
Five classes of LDL receptor mutations
Development of drugs to treat hypercholesterolemia based on
concepts learned from FH studies
Combined heart-liver transplant in an individual with
homozygous FH
Lessons from familial hypercholesterolemia
• Studies of an uncommon disease (FH) can have
important implications for a common disease
(coronary artery disease)
• Genetics studies of clinical traits can lead to an
understanding of basic biologic mechanisms
(receptor mediated endocytosis, cholesterol
homeostasis) as well as new therapies (statins).
Francis Collins (1995)
Schematic of the approach generally utilized for positional cloning
BACs
Families
+
Linkage
Analysis
Finer
Genetic
Mapping
Physical
Mapping
and
Cloning
Normal
Candidate
cDNAs
..A A C T C
Transcript
Identification
Mutation
Search
..A A G T C
Mutation
Genetic
Markers
Marfan Syndrome
-autosomal dominant disorder characterized by weakened connective tissue
-most life-treatening is aortic dissection (an aneurysm of the aorta)
-other symptoms include mitral valve prolapse, emphysema-like lung disease, and
ocular and skin disorders
-patients tend to be tall and lanky, with very long limbs, fingers and toes
Fibrillin 1 Gene Mutated in Marfan Syndrome Patients
(A) Single-strand conformational polymorphism screen
(B) DNA sequence
Letter
Nature Genetics 33, 407 - 411 (2003)
Published online: 24 February 2003;
Dysregulation of TGF- activation contributes to
pathogenesis in Marfan syndrome
Enid R. Neptune1, 2, Pamela A. Frischmeyer2, Dan E.
Arking2, Loretha Myers2, Tracie E. Bunton3, Barbara
Gayraud4, Francesco Ramirez4, Lynn Y. Sakai5 & Harry
C. Dietz2, 6
Lung histopathology and morphometry of mice
deficient in fibrillin-1.
Active TGF-B expression and signaling in lung
tissue of mice deficient in fibrillin-1.
Neutralizing antibody to TGF- rescues lung
maturation in mice deficient in fibrillin-1.
Mice deficient in fibrillin-1 have preserved lung cell
proliferation but greater apoptosis.
Model
Fibrillin deficiency
TGFB not sequestered
TGFB activated
Apoptosis in lung, bone overgrowth, etc.
A lesson: Structural matrix elements serve crucial
regulatory roles in cytokine activation and signalling
Identification of Mendelian and complex trait genes
1980-2002
Number of Mendelian genes
1600
Mendelian traits
100
All complex traits
90
Human complex traits
80
1400
70
1200
60
1000
50
800
40
600
30
400
20
200
10
0
1980
Number of complex trait genes
1800
0
1985
1990
Year
1995
2000
Glazer, et al. (2002) Science
Nature Genetics 34, 383 - 394 (2003)
VEGF is a modifier of amyotrophic lateral sclerosis in mice
and humans and protects motoneurons against ischemic
death
Diether Lambrechts1, Erik Storkebaum1, Masafumi
Morimoto1, Jurgen Del-Favero2, Frederik Desmet1,
Stefan L Marklund3, Sabine Wyns1, Vincent Thijs1,
Jörgen Andersson3, Ingrid van Marion4, Ammar AlChalabi5, Stephanie Bornes6, Rhiannon Musson4,
Valerie Hansen5, Lars Beckman3, Rolf Adolfsson7,
Hardev Singh Pall4, Hervé Prats6, Severine Vermeire1,
Paul Rutgeerts1, Shigehiro Katayama8, Takuya Awata8,
Nigel Leigh5, Loïc Lang-Lazdunski9, Mieke Dewerchin1,
Christopher Shaw5, Lieve Moons1, Robert Vlietinck1, 10,
Karen E Morrison4, Wim Robberecht1, Christine Van
Broeckhoven2, Désiré Collen1, Peter M Andersen3
& Peter Carmeliet1
VEGF Polymorphisms
Lesson
Basic vascular biology studies (regulation
of VEGF expression in response to
hypoxia) can lead to an understanding of a
complex disease