Team:MIT/Treatment

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<li><a href="#description">Description</a></li>

<li><a href="#description">Description</a></li>

<li><a href="#experiments">Experiments</a></li>

<li><a href="#experiments">Experiments</a></li>

<li><a href="#parts">Parts</a></li>

<li><a href="#parts">Parts</a></li>

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<font size=4><br />Down-regulating Aβ production and up-regulating Aβ degradation</font><br /><br />

<font size=4><br />Down-regulating Aβ production and up-regulating Aβ degradation</font><br /><br />

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<h2>Description</h2><a name="description"></a>

<h2>Description</h2><a name="description"></a>

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The second response activated by the release of rtTA is transcriptional expression of a miRNA targeted specifically to BACE1. We constructed four independent miRNA-generating vectors, each targeted to a different region of the BACE1 mRNA sequence. The benefit of having multiple unique miRNA’s is the ability to test the relative efficacy of each at down-regulating BACE1 translational expression. Predicting an effective miRNA depends on a variety of factors ranging from the sequence of bases that flank the guide region, to the degree of complementarity between the miRNA and its target, to the region of the target that the miRNA binds. <br>

The second response activated by the release of rtTA is transcriptional expression of a miRNA targeted specifically to BACE1. We constructed four independent miRNA-generating vectors, each targeted to a different region of the BACE1 mRNA sequence. The benefit of having multiple unique miRNA’s is the ability to test the relative efficacy of each at down-regulating BACE1 translational expression. Predicting an effective miRNA depends on a variety of factors ranging from the sequence of bases that flank the guide region, to the degree of complementarity between the miRNA and its target, to the region of the target that the miRNA binds. <br>

<h2>Experiments</h2><a name="experiments" ></a>

<h2>Experiments</h2><a name="experiments" ></a>

To test our miRNA’s effectiveness at down-regulating BACE1 expression we transfected separate HEK293 cultures with either (1) BACE1 under constitutive expression by the Hef1a promoter or (2) with BACE1 under constitutive expression by the Hef1a promoter and with a miRNA-generating vector inducibly regulated by the TRE promoter. We performed these transfections in duplicate—once with native BACE1, and then once with eYFP-tagged BACE1. There were two variants of this eYFP-tagged BACE1 construct—one with eYFP linked to the N-terminus of Bace1 and another with eYFP on the C-terminus. We created these two variants after considering the possibility that linking eYFP to either terminus of Bace1 might interfere with the peptide’s native structure or function. <br /> <br />

To test our miRNA’s effectiveness at down-regulating BACE1 expression we transfected separate HEK293 cultures with either (1) BACE1 under constitutive expression by the Hef1a promoter or (2) with BACE1 under constitutive expression by the Hef1a promoter and with a miRNA-generating vector inducibly regulated by the TRE promoter. We performed these transfections in duplicate—once with native BACE1, and then once with eYFP-tagged BACE1. There were two variants of this eYFP-tagged BACE1 construct—one with eYFP linked to the N-terminus of Bace1 and another with eYFP on the C-terminus. We created these two variants after considering the possibility that linking eYFP to either terminus of Bace1 might interfere with the peptide’s native structure or function. <br /> <br />

After transfection and Doxycycline-induction of our miRNA-generating vectors, we used flow cytometry to verify that the miRNA-generating vectors were being expressed. Proper splicing of the mature miRNA out of the expression vector leaves an intact mKate coding sequence in the vector, so emission of red fluorescence from our transfected HEK293 indicates proper miRNA processing. <br /> <br />

After transfection and Doxycycline-induction of our miRNA-generating vectors, we used flow cytometry to verify that the miRNA-generating vectors were being expressed. Proper splicing of the mature miRNA out of the expression vector leaves an intact mKate coding sequence in the vector, so emission of red fluorescence from our transfected HEK293 indicates proper miRNA processing. <br /> <br />

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The one important difference between the BACE1 and BACE2 experiments was only that the BACE2 experiment required a simpler initial transfection. We transfected two cultures of HEK293 with either (1) a vector inducibly expressing BACE2 under control of the TRE promoter or (2) with a vector inducibly expressing BACE2 under control of a TRE promoter and with a vector constitutively expressing the rtTA transcription factor. So by comparing the amount of BACE2 expression in the induced versus un-induced transfection samples, we could determine our effectiveness at up-regulating BACE2 expression. <br /> <br />

The one important difference between the BACE1 and BACE2 experiments was only that the BACE2 experiment required a simpler initial transfection. We transfected two cultures of HEK293 with either (1) a vector inducibly expressing BACE2 under control of the TRE promoter or (2) with a vector inducibly expressing BACE2 under control of a TRE promoter and with a vector constitutively expressing the rtTA transcription factor. So by comparing the amount of BACE2 expression in the induced versus un-induced transfection samples, we could determine our effectiveness at up-regulating BACE2 expression. <br /> <br />

<h2>Parts</h2><a name="parts" ></a>

<h2>Parts</h2><a name="parts" ></a>