Weibel-Palade body
Encyclopedia
Weibel-Palade bodies are the storage granules
of endothelial cells, the cells that form the inner lining of the blood vessel
s and heart
. They store and release two principal molecules, von Willebrand factor
and P-selectin
, and thus play a dual role in hemostasis
and inflammation
. They are named after
the two scientist
s who first described them in 1964.
(vWF), a multimeric protein
that plays a major role in blood
coagulation
. The other is P-selectin
, which plays a central role in the ability of inflamed
endothelial cells to recruit passing leukocytes (white blood cells), allowing them to exit the blood vessel (extravasate
) and enter the surrounding tissue, where they can migrate to the site of infection
or injury.
Additional Weibel-Palade body components are the chemokines Interleukin-8 and eotaxin-3, endothelin-1, angiopoietin-2, osteoprotegerin
, the tetraspanin
CD63/lamp3 and α-1,3-fucosyltransferase VI.
. VWD has an estimated prevalence in some human populations of up to 1%, and is most often characterized by prolonged and variable mucocutaneous bleeding. Type III von Willebrand Disease is a severe bleeding disorder, not unlike severe hemophilia type A or B. VWF acts in primary hemostasis
to recruit platelets at a site of injury, and is also important in secondary hemostasis
, acting as a chaperone for coagulation
factor VIII (FVIII).
from vWF dimers. The Golgi then buds off vesicles, covered in a lipid bilayer
, which consist almost exclusively of vWF. The only parallel organelle in physiology is the alpha granule of platelet
s, which also contains vWF. Weibel-Palade bodies are the main source of vWF, though, and α-granules probably play a minor role.
anatomist
Ewald R. Weibel and the Romanian
physiologist
George Emil Palade
in 1964. Prof. Palade was to win the Nobel Prize in Physiology or Medicine
in 1974 for his work on the function of organelles in cells
.
Granule (cell biology)
In cell biology, a granule is a small particle. It can be any structure barely visible by light microscopy. The term is most often used to describe a secretory vesicle.-Leukocytes:...
of endothelial cells, the cells that form the inner lining of the blood vessel
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...
s and heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
. They store and release two principal molecules, von Willebrand factor
Von Willebrand factor
von Willebrand factor is a blood glycoprotein involved in hemostasis. It is deficient or defective in von Willebrand disease and is involved in a large number of other diseases, including thrombotic thrombocytopenic purpura, Heyde's syndrome, and possibly hemolytic-uremic syndrome...
and P-selectin
P-selectin
P-selectin is a cell adhesion molecule on the surfaces of activated endothelial cells, which line the inner surface of blood vessels, and activated platelets...
, and thus play a dual role in hemostasis
Hemostasis
Hemostasis or haemostasis is a process which causes bleeding to stop, meaning to keep blood within a damaged blood vessel . Most of the time this includes blood changing from a liquid to a solid state. Intact blood vessels are central to moderating blood's tendency to clot...
and inflammation
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
. They are named after
Eponym
An eponym is the name of a person or thing, whether real or fictitious, after which a particular place, tribe, era, discovery, or other item is named or thought to be named...
the two scientist
Scientist
A scientist in a broad sense is one engaging in a systematic activity to acquire knowledge. In a more restricted sense, a scientist is an individual who uses the scientific method. The person may be an expert in one or more areas of science. This article focuses on the more restricted use of the word...
s who first described them in 1964.
Constituents
There are two major components stored within Weibel-Palade bodies. One is von Willebrand factorVon Willebrand factor
von Willebrand factor is a blood glycoprotein involved in hemostasis. It is deficient or defective in von Willebrand disease and is involved in a large number of other diseases, including thrombotic thrombocytopenic purpura, Heyde's syndrome, and possibly hemolytic-uremic syndrome...
(vWF), a multimeric protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
that plays a major role in blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
coagulation
Coagulation
Coagulation is a complex process by which blood forms clots. It is an important part of hemostasis, the cessation of blood loss from a damaged vessel, wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel...
. The other is P-selectin
P-selectin
P-selectin is a cell adhesion molecule on the surfaces of activated endothelial cells, which line the inner surface of blood vessels, and activated platelets...
, which plays a central role in the ability of inflamed
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
endothelial cells to recruit passing leukocytes (white blood cells), allowing them to exit the blood vessel (extravasate
Leukocyte extravasation
Leukocyte extravasation is the movement of leukocytes out of the circulatory system, towards the site of tissue damage or infection. This process forms part of the innate immune response, involving the recruitment of non-specific leukocytes...
) and enter the surrounding tissue, where they can migrate to the site of infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
or injury.
Additional Weibel-Palade body components are the chemokines Interleukin-8 and eotaxin-3, endothelin-1, angiopoietin-2, osteoprotegerin
Osteoprotegerin
Osteoprotegerin , also known as osteoclastogenesis inhibitory factor , or tumor necrosis factor receptor superfamily member 11B , is a protein that in humans is encoded by the TNFRSF11B gene...
, the tetraspanin
Tetraspanin
Tetraspanins are a family of membrane proteins found in all multicellular eukaryotes.Tetraspanins, also called tetraspans or the transmembrane 4 superfamily , have four transmembrane domains, intracellular N- and C-termini and two extracellular domains, one short and one longer, typically 100...
CD63/lamp3 and α-1,3-fucosyltransferase VI.
Clinical significance
The importance of Weibel-Palade bodies are highlighted by some human disease mutations. Mutations within vWF are the usual cause of the most common inherited bleeding disorder, von Willebrand diseaseVon Willebrand disease
von Willebrand disease is the most common hereditary coagulation abnormality described in humans, although it can also be acquired as a result of other medical conditions. It arises from a qualitative or quantitative deficiency of von Willebrand factor , a multimeric protein that is required for...
. VWD has an estimated prevalence in some human populations of up to 1%, and is most often characterized by prolonged and variable mucocutaneous bleeding. Type III von Willebrand Disease is a severe bleeding disorder, not unlike severe hemophilia type A or B. VWF acts in primary hemostasis
Hemostasis
Hemostasis or haemostasis is a process which causes bleeding to stop, meaning to keep blood within a damaged blood vessel . Most of the time this includes blood changing from a liquid to a solid state. Intact blood vessels are central to moderating blood's tendency to clot...
to recruit platelets at a site of injury, and is also important in secondary hemostasis
Hemostasis
Hemostasis or haemostasis is a process which causes bleeding to stop, meaning to keep blood within a damaged blood vessel . Most of the time this includes blood changing from a liquid to a solid state. Intact blood vessels are central to moderating blood's tendency to clot...
, acting as a chaperone for coagulation
Coagulation
Coagulation is a complex process by which blood forms clots. It is an important part of hemostasis, the cessation of blood loss from a damaged vessel, wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel...
factor VIII (FVIII).
Production
Multimeric vWF is assembled in the Golgi apparatusGolgi apparatus
The Golgi apparatus is an organelle found in most eukaryotic cells. It was identified in 1898 by the Italian physician Camillo Golgi, after whom the Golgi apparatus is named....
from vWF dimers. The Golgi then buds off vesicles, covered in a lipid bilayer
Lipid bilayer
The lipid bilayer is a thin membrane made of two layers of lipid molecules. These membranes are flat sheets that form a continuous barrier around cells. The cell membrane of almost all living organisms and many viruses are made of a lipid bilayer, as are the membranes surrounding the cell nucleus...
, which consist almost exclusively of vWF. The only parallel organelle in physiology is the alpha granule of platelet
Platelet
Platelets, or thrombocytes , are small,irregularly shaped clear cell fragments , 2–3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes. The average lifespan of a platelet is normally just 5 to 9 days...
s, which also contains vWF. Weibel-Palade bodies are the main source of vWF, though, and α-granules probably play a minor role.
History
Weibel-Palade bodies were initially described by the SwissSwitzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
anatomist
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...
Ewald R. Weibel and the Romanian
Romanians
The Romanians are an ethnic group native to Romania, who speak Romanian; they are the majority inhabitants of Romania....
physiologist
Physiology
Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...
George Emil Palade
George Emil Palade
George Emil Palade was a Romanian cell biologist. Described as "the most influential cell biologist ever", in 1974 he was awarded the Nobel Prize in Physiology and Medicine, together with Albert Claude and Christian de Duve. The prize was granted for his innovations in electron microscopy and...
in 1964. Prof. Palade was to win the Nobel Prize in Physiology or Medicine
Nobel Prize in Physiology or Medicine
The Nobel Prize in Physiology or Medicine administered by the Nobel Foundation, is awarded once a year for outstanding discoveries in the field of life science and medicine. It is one of five Nobel Prizes established in 1895 by Swedish chemist Alfred Nobel, the inventor of dynamite, in his will...
in 1974 for his work on the function of organelles in cells
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
.