Introduction to Hedgehog Signaling: Hedgehog Protein Synthesis and Release

hey everyone in this lesson we're going to talk about Hedgehog protein synthesis so this will be the beginning of a series of lessons where I talk about the Hedgehog signaling pathway so in this lesson we're going to focus on how Hedgehog proteins are actually synthesized and released so to begin what are the Hedgehog proteins well they are as I mentioned secreted proteins and they are segment polarity proteins and in mammals are actually three homologs of Hedgehog proteins one is known as sonic so we call it sonic hedgehog or SH H another one is Indian Hedgehog or IH H and the other one is desert or DHH now all these Hedgehog proteins are involved in the Hedgehog signaling pathway and the Hedgehog signaling pathway itself is involved in embryological development and more specifically we see an example of this in the digit or finger finger formation in mammals now the Hedgehog proteins themselves are synthesized within the endoplasmic reticulum and there are actually four mechanisms of release and secretion which we'll talk about in the next slide so how do Hedgehog proteins get synthesized well we mentioned that Hedgehog proteins get synthesized in the endoplasmic reticulum and in fact they actually get synthesized as a precursor protein of about 45 kilo daltons in weight and the precursor protein has two portions as all proteins do it has a end terminal portion in a C terminal portion and the important reason why I have these portions of the protein as separate entities is that they actually have functions in and of themselves and in fact the H HC or the Hedgehog C terminal portion of the protein has a particular function in that it actually adds a cholesterol to the Hedgehog in terminal portion of the protein now as this protein becomes processed within the implants will reticulum the Hedgehog C terminal portion of the probe gets cleaved off in an auto proteolytic cleavage process and this leaves the HH n or the hedgehog in terminal portion of the protein with its cholesterol moiety attached now the h HC portion of the protein gets exported out of the endoplasmic reticulum and degraded by a proteasome in the cell now when we have the HH in protein with its cluster own moiety attached there's actually another protein known as skinny Hedgehog or s ki which is actually within the endoplasmic reticulum membrane and this protein actually acts on the hhn protein and adds a pol medic acid to it so now the hhn protein has a palmitic acid moiety and a cholesterol moiety attached to it now once it has both of these moieties once the h hn has both of these moieties attached to it it actually gets exported out of the inter plasmic reticulum and gets placed into the plasma membrane of the cell now the Hedgehog protein itself now will then be acted on by a protein within the plasma membrane known as dispatched and there's also another protein involved in this process known as Scoob - and what happens is the Scoob - and the H H n over the Hedgehog mature protein get attached to each other and they actually get released from the plasma membrane and in fact this is one of the ways in which the Hedgehog proteins are released so this is the first mechanism so again the first mechanism of Hedgehog protein release is by the Hedgehog protein with its two moieties being acted on by dispatched and the scoop to protein attaching to the Hedgehog protein and then these two proteins the Hedgehog and the Scoob two proteins get released and that is the first mechanism of release of the Hedgehog proteins now another way by which the Hedgehog proteins can be released from the cell involves the Hedgehog proteins accumulating on the plasma membrane so if we keep releasing the hhn protein from the endoplasmic reticulum it can accumulate on the plasma plasma membrane and then these proteins can then actually be released themselves as a soluble multum or so they'll all aggregate together and then they can actually pop off of the plasma membrane and this is in fact the second way that Hedgehog proteins can be released from the cell now the third way is similar to the second way and that the Hedgehog proteins can accumulate within the plasma membrane but this time they actually can interact with a protein known as Naadam and they can interact with the heparin sulfate chains on glyphicon now the heparin sulfate chains enable the Hedgehog proteins to actually recruit lipo foreign Apryl lipoproteins and in this way they can actually get incorporated into a lipoprotein themselves to be released and this is the third way Hedgehog proteins can be released from a cell now the fourth way is again similar in that the Hedgehog proteins can again accumulate within the plasma membrane but this time the plasma membrane itself can actually bud off from the cell as a EXO vesicle and this is the fourth way that Hedgehog proteins can be released from the cell and that is the last way the Hedgehog proteins can release we mentioned that there are four mechanisms and those are the four mechanisms of release of Hedgehog proteins anyways guys that was a quick lesson on Hedgehog protein synthesis and release I hope you found this video helpful if you did please like and subscribe for more videos like this one and as always thank you so much for watching and I'll see you next time

Channel: JJ Medicine

Views: 14,990

Rating: 4.8805971 out of 5

Keywords: Hedgehog signaling, Hedgehog signalling, Hedgehog signalling pathway, Hedgehog signaling pathway, Hedgehog signaling lesson, Hedgehog signalling lesson, Hedgehog signaling animation, Hedgehog signalling animation, Hedgehog protein synthesis, Hedgehog protein production, Hedgehog synthesis, Hedgehog protein signaling, Hedgehog protein signalling, indian hedgehog protein, Hedgehog protein release, Hedgehog protein secretion, hedgehog pathway, hedgehog signaling pathway review

Id: U6xGh2AKaD4

Length: 6min 37sec (397 seconds)

Published: Sun Jan 21 2018