Editing DNA vaccine (section)

=== DNA uptake mechanism ===

When DNA uptake and subsequent expression was first demonstrated ''in vivo'' in [[muscle]] cells,<ref name=Wolff1992>{{cite journal | vauthors = Wolff JA, Dowty ME, Jiao S, Repetto G, Berg RK, Ludtke JJ, Williams P, Slautterback DB | display-authors = 6 | title = Expression of naked plasmids by cultured myotubes and entry of plasmids into T tubules and caveolae of mammalian skeletal muscle | journal = Journal of Cell Science | volume = 103 | issue = 4 | pages = 1249–1259 | date = December 1992 | pmid = 1487500 | doi = 10.1242/jcs.103.4.1249 | series = 103 }}</ref> these cells were thought to be unique because of their extensive network of T-tubules. Using [[electron microscopy]], it was proposed that DNA uptake was facilitated by [[caveolae]] (or, non-clathrin coated pits).<ref name=Anderson1992>{{cite journal | vauthors = Anderson RG, Kamen BA, Rothberg KG, Lacey SW | title = Potocytosis: sequestration and transport of small molecules by caveolae | journal = Science | volume = 255 | issue = 5043 | pages = 410–411 | date = January 1992 | pmid = 1310359 | doi = 10.1126/science.1310359 | bibcode = 1992Sci...255..410A }}</ref> However, subsequent research revealed that other cells (such as [[keratinocytes]], [[fibroblasts]] and [[epithelial]] [[Langerhans cells]]) could also internalize DNA.<ref name=Raz1996/><ref name=Casares1997>{{cite journal | vauthors = Casares S, Inaba K, Brumeanu TD, Steinman RM, Bona CA | title = Antigen presentation by dendritic cells after immunization with DNA encoding a major histocompatibility complex class II-restricted viral epitope | journal = The Journal of Experimental Medicine | volume = 186 | issue = 9 | pages = 1481–1486 | date = November 1997 | pmid = 9348305 | pmc = 2199124 | doi = 10.1084/jem.186.9.1481 }}</ref> The mechanism of DNA uptake is not known.

Two theories dominate – that ''in vivo'' uptake of DNA occurs non-specifically, in a method similar to [[phagocytosis|phago]]- or [[pinocytosis]],<ref name=Lewis1999 /> or through specific receptors.<ref name=Bennett1985>{{cite journal | vauthors = Bennett RM, Gabor GT, Merritt MM | title = DNA binding to human leukocytes. Evidence for a receptor-mediated association, internalization, and degradation of DNA | journal = The Journal of Clinical Investigation | volume = 76 | issue = 6 | pages = 2182–2190 | date = December 1985 | pmid = 3001145 | pmc = 424340 | doi = 10.1172/JCI112226 }}</ref> These might include a 30kDa surface [[immune receptor|receptor]], or {{Clarify | text = [[macrophage]] scavenger receptors. | date = November 2021 | reason = Unclear if 'scavanger' is a modifer for macrophage, or receptor, i.e. does scavenger meant to indicate that macrophage is a scavanger, or meant to indicate specific types of macrophage's receptors?}} The 30kDa surface receptor binds specifically to 4500-bp DNA fragments (which are then internalised) and is found on professional APCs and T-cells. Macrophage scavenger receptors bind to a variety of macromolecules, including poly[[ribonucleotides]] and are thus candidates for DNA uptake.<ref name=Bennett1985 /><ref name=Bennet1988>{{cite journal | vauthors = Bennet RM, Hefeneider SH, Bakke A, Merritt M, Smith CA, Mourich D, Heinrich MC | title = The production and characterization of murine monoclonal antibodies to a DNA receptor on human leukocytes | journal = Journal of Immunology | volume = 140 | issue = 9 | pages = 2937–2942 | date = May 1988 | doi = 10.4049/jimmunol.140.9.2937 | pmid = 2452195 | s2cid = 22923379 | url = http://www.jimmunol.org/cgi/content/abstract/140/9/2937 | doi-access = free }}</ref> Receptor-mediated DNA uptake could be facilitated by {{Clarify | text = the presence of [[guanine|polyguanylate sequences]]. | date = October 2021 | reason = Where are the said polyguanylate sequences?  Presumably DNA.}}{{Citation needed | date = October 2021}} [[Gene gun]] delivery systems, [[Transfection#Lipofection|cationic liposome packaging]], and other delivery methods bypass this entry method, but understanding it may be useful in reducing costs (e.g. by reducing the requirement for cytofectins), which could be important in animal husbandry.