RNA interference
I was once asked why our A&P textbook (Anatomy & Physiology 7th edition) includes information about RNA interference (RNAi) while most other A&P textbooks do not. Why do students need to know about that?
This question is almost certainly triggered by the questioner's years of experience teaching A&P successfully without mentioning RNAi or its roles in human biology.
If it ain't broke, don't fix it, right? Good advice in general, I guess, but this maxim does not apply to the idea that we need to continually update our courses in order to serve our students well.
The recent discovery in 1998 of RNAi and its functions is one reason it has been slow to enter the commonly taught A&P curriculum. But its important role in human biology is now widely recognized.
What is RNA interference (RNAi)?
It is a recently discovered process in cells that stops the action of specific genes by destroying mRNA and thus preventing translation of the gene product.
The diagram below summarizes the process of RNAi:
- Dicer (enzyme) chops double-stranded RNA (dsRNA) into small pieces called short interfering RNA (siRNA)
- siRNA combines with protein subunits to form an RNA-induced silencing complex (RISC)
- The siRNA within RISC unzips, exposing anticodons and thus "activating" the RISC
- Activated RISC binds to target mRNA (with complementary codons)
- RISC causes target mRNA to break apart, preventing translation of the gene product
Click image for source and link to high-resolution image
In Anatomy & Physiology 7th edition is explained and illustrated in a full-page boxed essay entitled The RNA Revolution on p. 112 (see also pp. 58 and 111).
Here are a few (of many) reasons that including RNAi in an A&P course is useful:
- RNAi plays a role in defending our cells against viruses by stopping viral genetic code from being translated in host cells
- This may one day play a key role in understanding previously unknown immune mechanisms
- RNAi mechanisms may be harnessed to develop therapies to manage or even cure a variety of viral infections
- RNAi mechanisms may one day serve as the basis for a new type of "vaccine" against viral infections
- This may one day play a key role in understanding previously unknown immune mechanisms
- RNAi likely plays a role in the normal regulation of gene activity in a cell by preventing translation of the gene product(s)
- Knowledge of RNAi mechanisms will probably be essential in understanding the genetic mechanisms of normal human biology . . . an understanding that is already taking a central role in clinical medicine
- Knowledge of RNAi mechanisms will probably be essential in understanding the genetic mechanisms of normal human biology . . . an understanding that is already taking a central role in clinical medicine
- RNAi is increasingly used as method for "knocking out" a particular gene's effects in research animals in order to study the gene's functions
- RNAi is becoming a more frequently used research tool in life science research . . . thus making knowledge of RNAi essential to making research applications to clinical science
- RNAi is becoming a more frequently used research tool in life science research . . . thus making knowledge of RNAi essential to making research applications to clinical science
- RNAi is being used to treat genetic disease. . . an application that will likely expand greatly over the next few decades
- See p. 1124 in Anatomy & Physiology 7th editionregarding RNAi therapy
- RNAi therapy is already in use and promises to be a common type of therapy in the coming decades
- See p. 1124 in Anatomy & Physiology 7th editionregarding RNAi therapy
- RNAi has been shown to be a mechanism of disease
- For example, certain forms of progressive hearing loss were recently shown to result from inherited mutations in microRNA that perform gene silencing in the hair cells of the spiral (Corti) organ of the ear
- As science discovers more RNAi mechanisms, our understanding of disease will broaden
- For example, certain forms of progressive hearing loss were recently shown to result from inherited mutations in microRNA that perform gene silencing in the hair cells of the spiral (Corti) organ of the ear
How deeply to cover RNA interference in a beginning A&P course? I think mentioning what it is—in simple terms—and some of its primary functions in humans is quite enough. Although my two-semester A&P textbook does provide a diagram of the steps involved, that is meant more as a help in visualizing it as a process and not necessarily as a "you need to know every detail of this process" illustration.
Simple coverage is enough to introduce beginning students sufficiently to be prepared for their inevitable later encounters with RNAi.
Teaching Resources
This article written for public consumption summarizes the discovery of RNA interference. It includes some excellent diagrams. It was originally produced to explain the 2006 Nobel Prize in Medicine or Physiology given to Fire and Mellow "for their discovery of RNA interference—gene silencing by double-stranded RNA."
RNA interference
from NobelPrize.org
Nova ScienceNOW (the PBS television series) has a number of FREE resources you can use in your course:
- RNA interference is a 15-minute video explaining RNA interference
- RNAi Explained interactive presentation summarizes the process of RNA interference in very simple terms
- The RNAi Cure illustrated article summarizes the use of RNAi to treat genetic disorders
HINT: I use the ScienceNOW video and other resources in my course as an "extra credit" activity that includes an online quiz that reviews the material presented in program and related resources. |
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This interactive Flash presentation from HMMI is a great teaching and learning resource that students can use for FREE:
Biointeractive: RNA interference
This video is more detailed than needed for the typical A&P course, but is a good visualization of the process.
