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Profession: Medial Doctor, Lecturer, Pathologist
Previous Employment: Military physician
Research: Bone marrow, skin structure, connective tissue structure
Other Education: Classical studies in high school
Accomplishments: Meteucci Prize for highest grades in college, numerous publications (even before the age of 20)
Social Beliefs: Italian liberation from Austria Bizzozero's discovery of his nodes Please, sit with me and imagine a world without electrical plugs. There is no machinery hum ringing in your subconscious. The light from a kerosine lamp is being reflected into your microscope. You are staring at the epidermis of human skin through the microscope... hours pass.... stratum corneum... stratum granulosum... stratum spinosum... stratum germinativum... stratum corneum... stratum granulosum... stratum spinosum... stratum germinativum... stratum corneum... stratum granulosum... stratum spinosum... stratum germinativum... Nodes or not nodes? Are you seriously delving into definitions? OF COURSE I AM! The history and contemporary knowledge of desmosomes The structure that is a desmosome -An area of adherence between two cells
-Cadherins on the outside of the cell link to keratin intermediate filaments inside the cell (cytoplasmic plaque)
-Found on lateral aspect of cells
The function of desmosomes -A primary function of a desmosome is to form stable adhesive junctions between cells (Dubash, 2011).
Diseases related to desmosomes... -Naxos Disease
That is an impressive resume, my friend. Bizzozero studied the stratum spinosum of the epidermis and saw that there were "dense bodies" connecting the keratinocytes. He named them nodes because in anatomy nodes are small masses or lumps. He did not have the means to know what they were actually made of. Bizzozero was not incorrect; he was imprecise due to his technological handicap. So are they nodes?
One might think that while looking at it in the same manner we could call them that. But now we know that they are not just dense bodies between the cells... but let's give the man a little credit for being the empiricist he was. STRATUM SPINOSUM! Bizzozero noted the darker areas of the stratum spinosum and concluded that these held each cell to the adjacent cell. THE SCIENTIFIC COMMUNITY "We think that the dark areas that you are seeing are cellular bridges that create cytoplasmic continuity." BIZZOZERO "No I'm pretty sure that these dense bodies create cellular adhesion..." THE SCIENTIFIC COMMUNITY "We don't think so. You're wrong." THE RESEARCHER "I'm noticing a trend in the history of science..." Bizzozero "How would I know who she is? Back to the topic of these nodes connecting cells..." THE SCIENTIFIC COMMUNITY "Give it up. Anyway, we have Mr. Ranvier on our side...Perhaps you've heard of him?" "Who is this girl and why is she talking?" THE SCIENTIFIC COMMUNITY THE RESEARCHER "If only you had electron microscopy, Dr. Bizzozero!" Although his thoughts were correct, it would not be until decades after his death that his theory would be validated. -Researchers now believe that desmosomes serve more purposes than just cellular adhesion. Studies have shown that desmosomal proteins play a role in cell signaling. -Ectodermal Dysplasia - Cancer -cardiomyopathy
-wooly hair -skin fragility
-sparse hair - desmosome proteins may have tumor suppressing properties (more research to be done) A Likeness of Bizzozero In a world where there were no desmosomes... Without desmosomes vertebrates would be unable to maintain tissue creation and homeostasis and would not have structural support. Lindsey Mendez
Case Western Reserve University
December 2012 Nodes are actually desmosomes In 1920, Joseph Schaffer coined the term desmosome by combining two Greek words "desmo" and "soma."
"Desmo" means bond and "soma" means body.
Therefore, we no longer call these adhering structures Bizzozero's Nodes. Junctional Complex Differences Zonula occludens: tight seal formed by claudins and occludins
Zonula adherens: junctional complex just basal to a zonula occludens; is made of extracellular domains of plasma membrane cell adhesion molecules
Macula adherens: made of cadherins and keratin intermediate tono filaments Please remember that desmosomes are sites of adjacent cell adhesion AND they occur along areas of lateral intercalated discs. This mixed with gap junctions makes them an important character especially between cardiac myocytes. What proteins make up a desmosome? Transmembrane:
cadherins, desmogleins, and desmocallins
plakophilins and plakoglobin Transmembrane Proteins Cadherins, desmogleins and desmocallins connect cells together by interacting with the extracellular space. Intracellular Proteins Intermediate filaments are "cytoskeletal fibers found in virtually all tissues."
Plakophilins and plakoglobins are part of the armidillo protein family --> they provide stability
Desmoplakin, a plakin family member, tethers the intermediate filaments with the desmosomal junctional complex Oh, and did I mention that desmosomes are also called macula adherens which means "adhering spot?" References Dubash, Adi D. and Kathleen J. Green. Desmosomes. Current Biology. 2011, July 26 21(14).
Emanuella, Delva et al. The Desmosome. Coldspring Harbor Perspectives on Biology, 2009, August 1 (2).
Holthofer, Bastian et al. Structure and Function of Desmosomes. International Review of Cytology, 2007, 264.
Paolo Mazzarello, Allesandro L. Calligaro and Alberto Calligaro. Guilo Bizzozero: a pioneer of cell biology. Nature Reviews. Molecular Cell Biology. 2001, October. 2 (10).
National Foundation for Ectodermal Dysplasias. <http://nfed.org/>. 2010. (accessed 10 December 2012).
Protonotarios, Nikos and Adalena Tsatsopoulou. Naxos Disease. Indian Pacing and Electrophysiology Journal. 2005. 5 (2).