genetics of vascular diseases jake lusis 3-730 mrl [email protected]
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Carl Miller, ~1938, Oslo County Hospital, Norway
Inheritance of:
Cholesterol level (mg/dl):
Tendon xanthomas:
Early coronary artery disease (under 55 years of age):
330 210
Tendon Xanthomas
Cosegregation of triad of xanthomas, high cholesterol and early heart disease
210190 400
210 430 490420 180
170420
Inheritance of:
Cholesterol level (mg/dl):
Tendon xanthomas:
Early coronary artery disease (under 55 years of age):
210 230
810 420
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
FH homozygote
Normal
Experiments with fibroblasts from normal and FH individuals
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
cultured skin fibroblastsisolate plasma membrane
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 cloningSchematic of the approach generally utilized for positional cloning
FamiliesFamilies PhysicalPhysical
MappingMapping
andand
CloningCloning
FinerFiner
GeneticGenetic
MappingMappingLinkageLinkage
AnalysisAnalysis++
TranscriptTranscript
IdentificationIdentification
CandidateCandidatecDNAscDNAs
MutationMutation
SearchSearch
..A A C T C..A A C T C
..A A G T C..A A G T C
BACsBACs
NormalNormal
MutationMutation
GeneticGeneticMarkersMarkers
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.
Figure 3
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
TGF 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
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Year
Number of Mendelian genes
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Number of complex trait genes
Mendelian traits
All complex traits
Human complex traits
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 deathDiether Lambrechts1, Erik Storkebaum1, Masafumi Morimoto1, Jurgen Del-Favero2, Frederik Desmet1, Stefan L Marklund3, Sabine Wyns1, Vincent Thijs1, Jörgen Andersson3, Ingrid van Marion4, Ammar Al-Chalabi5, 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