This work was supported by the Alzheimer&#8217;s Association (NIRG-10-171721; to U.H.), National Institute of Mental Health (MH096702; to U.H.), National Institute of Neurological Disorders and Stroke (NS081333; to C.M.T.), and pilot study awards from the National Institute on Aging-funded Alzheimer&#8217;s Disease Research Center at Columbia University (AG008702; to J.B. and Y.Y.J.) that also supports the New York Brain Bank. We thank members of the Hengst laboratory for comments and discussions

All animal procedures were approved by the IACUC of Columbia University and applicable guidelines for the care and use of laboratory animals were followed. Note: Prepare all buffers used for the ISH procedures in RNase-free or DEPC-treated water. This recommendation is not strictly necessary after ISH has been completed but it is suggested that buffers are still prepared in autoclaved double-distilled water and/or sterilized by filtering.
1. Detection of Atf4 mRNA Localized to Cholinerg...

<ol>
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In this report we describe the use of a high-resolution ISH technology in the detection of axonally localized Atf4 mRNA. These and previous published studies show that this technology is compatible with antibody-based protein detection in tissues or even whole embryos33. Importantly, it has been recently used for the detection of Arc mRNA within dendrites of hippocampal neurons34. It can also be combined with histological dyes for tissue staining. Finally, it is suitable for the si...

Axonal mRNA recruitment and local translation enable axons to respond to extracellular stimuli in a temporally and spatially acute manner1. Intra-axonal protein synthesis is best understood in the context of neurodevelopment where it plays crucial roles in growth cone behavior2-8, axon pathfinding9-11 and retrograde signaling12,13. But far less is known about the functional significance of axonal protein synthesis in post-developmental neurons when axonal mRNA and ribosome levels are greatly reduced14,15. Mature vertebrate axons have long been thought to be translationally inactive16. However, recent studies indicate that local translation is reactivated in mature axons under pathological conditions. For instance, a subset of mRNAs is recruited to regenerating axons following nerve injury and intra-axonal protein synthesis is required for the correct regeneration of these axons17. Additionally, our group has demonstrated that specific mRNAs are recruited to axons after local exposure to the Alzheimer&#8217;s disease peptide A&#946;1-42, and local translation of the transcription factor ATF4 is required to propagate the neurodegenerative effects of A&#946;1-42 from axons to the neuronal soma18. Finally, high throughput analyses have revealed that mature axons have a more complex and dynamic transcriptome than expected18-21, especially under pathological conditions. In light of these studies, a highly sensitive and specific method to detect axonally localized mRNAs in the adult nervous system is needed.
Much of the work on mRNA recruitment and local translation in mature axons has been performed on cultured neurons. This is especially true for transcriptome analyses since specialized culturing methods exist that allow the isolation of axons from the somato-dendritic compartment18-20. Although such studies have given valuable insight into the role of local translation in mature axons, the question whether cultured neurons faithfully represent the situation in vivo or if mRNA recruitment is an adaptive response of axons to culturing conditions is still open. Few studies have provided evidence of mRNA recruitment to mature axons in vivo. For example, the transcript coding for the olfactory marker protein has been detected in axons in adult sensory neurons22. A transgene containing the 3&#8217; UTR of &#946;-actin mRNA is transported to axons in peripheral and central nervous system neurons in mice and is locally translated after developmental periods23. Lamin b2 mRNA is localized to retinal axons in Xenopues laevis tadpoles and its depletion affects axon maintenance after axonal development21. Interference with the axonal transport of the mRNA encoding for cytochrome C oxidase IV alters mouse behavior24. Finally, Atf4 mRNA is found in adult axons of mice and human brains in the context of A&#946;1-42-induced neurodegeneration18.
High throughput transcriptome analyses have proven to be useful to identify mRNA profiles in isolated axons in vitro but have limitations for in vivo studies since in whole tissues axons are never found in isolation but intermingled with neuronal cell bodies, glial cells and other cell types. Thus, such analyses have to be combined with imaging techniques that confirm the subcellular localization of mRNAs. RNA in situ hybridization (RNA ISH) allows the detection and visualization of specific RNA sequences in cells and tissues. However, original RNA ISH assays were suitable only for the identification of highly abundant RNAs25, which is rarely the case for axonally localized mRNAs. For the last decades increasing efforts have been put into developing novel technologies that allow the detection of mRNAs at the single-molecule level25,26. For instance, Singer and colleagues have developed ISH probes to detect mRNAs in single cells, consisting in 5 non-overlapping fluorescently labelled 50-mers (for details refer to 27). The main difference between the above mentioned techniques and the one here described is that the later uses 20 double Z-structure (not linear) probes that typically target ~ 1 kb region of the RNA of interest ensuring specificity and low background levels. Probes are then hybridized with preamplifier and amplifier sequences that are finally fluorescently labeled or conjugated with enzymes that allow chromogenic reactions. These amplification steps improve the signal-to-noise ratio compared to other ISH technologies28. Here we describe two protocols using RNAscope combined either with fluorescence immunocytochemistry or with histological dyes allowing axonal counterstaining. Both protocols are suitable to visualize axonal localization of Atf4 mRNA in adult mouse and human brains.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>custom probe targeting residues 20-1381 of the mouse Atf4 mRNA (NM_009716)</td>
			<td>Advanced Cell Diagnostics</td>
			<td>-</td>
			<td>probe</td>
		</tr>
		<tr>
			<td>custom probe targeting residues 15-1256 of the human ATF4 mRNA (NM_001675.2)</td>
			<td>Advanced Cell Diagnostics</td>
			<td>-</td>
			<td>probe</td>
		</tr>
		<tr>
			<td>negative control probe-DapB</td>
			<td>Advanced Cell Diagnostics</td>
			<td align="right">310043</td>
			<td>probe</td>
		</tr>
		<tr>
			<td>positive control probe-mouse Polr2A (optional)</td>
			<td>Advanced Cell Diagnostics</td>
			<td align="right">312471</td>
			<td>probe</td>
		</tr>
		<tr>
			<td>positive control probe-human PPIB (optional)</td>
			<td>Advanced Cell Diagnostics</td>
			<td align="right">313901</td>
			<td>probe</td>
		</tr>
		<tr>
			<td>RNAscope Fluorescent Multiplex Reagent Kit (for fluorescence detection)</td>
			<td>Advanced Cell Diagnostics</td>
			<td align="right">320850</td>
			<td>In situ hybridization kit</td>
		</tr>
		<tr>
			<td>RNAscope 2.0 HD Reagent Kit - BROWN (for chromogenic detection)</td>
			<td>Advanced Cell Diagnostics</td>
			<td align="right">310035</td>
			<td>In situ hybridization kit</td>
		</tr>
		<tr>
			<td>Goat polyclonal anti-ChAT antibody</td>
			<td>Millipore</td>
			<td>AB144P</td>
			<td></td>
		</tr>
		<tr>
			<td>Luxol Fast Blue-Cresyl Echt Violet Stain Kit</td>
			<td>American MasterTech</td>
			<td>KTLFB</td>
			<td></td>
		</tr>
		<tr>
			<td>Clearify clearing agent (xylene substitute)</td>
			<td>American MasterTech</td>
			<td>CACLEGAL</td>
			<td></td>
		</tr>
		<tr>
			<td>ProLong Gold mounting&#160; medium with DAPI</td>
			<td>Life Technologies</td>
			<td>P36935</td>
			<td></td>
		</tr>
		<tr>
			<td>DPX mounting medium</td>
			<td>Sigma</td>
			<td align="right">6522</td>
			<td></td>
		</tr>
	</tbody>
</table>

detection of axonally localized mrnas in brain sections using high-resolution in situ hybridization

mRNAs are frequently localized to vertebrate axons and their local translation is required for axon pathfinding or branching during development and for maintenance, repair or neurodegeneration in postdevelopmental periods. High throughput analyses have recently revealed that axons have a more dynamic and complex transcriptome than previously expected. These analysis, however have been mostly done in cultured neurons where axons can be isolated from the somato-dendritic compartments. It is virtually impossible to achieve such isolation in whole tissues in vivo. Thus, in order to verify the recruitment of mRNAs and their functional relevance in a whole animal, transcriptome analyses should ideally be combined with techniques that allow the visualization of mRNAs in situ. Recently, novel ISH technologies that detect RNAs at a single-molecule level have been developed. This is especially important when analyzing the subcellular localization of mRNA, since localized RNAs are typically found at low levels. Here we describe two protocols for the detection of axonally-localized mRNAs using a novel ultrasensitive RNA ISH technology. We have combined RNAscope ISH with axonal counterstain using fluorescence immunohistochemistry or histological dyes to verify the recruitment of Atf4 mRNA to axons in vivo in the mature mouse and human brains.

A brief summary of the procedures described above is shown in Figure 1.
Optimal detection of Atf4 mRNA granules in cholinergic axons using heat-induced unmasking
When assessing axonal localization of mRNAs, it is critical to be able to identify the axons and to be able to visualize low abundant RNAs. The RNA ISH technology described here enables the detection of RNAs at a single-molecule resolution. Standard protocols using this technology ...

Watch this Scientific Journal Video about Detection of Axonally Localized mRNAs in Brain Sections Using High-Resolution In Situ Hybridization at JoVE.com

Detection of Axonally Localized mRNAs in Brain Sections Using High-Resolution In Situ Hybridization

RNA in situ hybridization (ISH) enables the visualization of RNAs in cells and tissues. Here we show how combination of RNAscope ISH with immunohistochemistry or histological dyes can be successfully used to detect mRNAs localized to axons in sections of mouse and human brains.

Detection of Axonally Localized mRNAs in Brain Sections Using High-Resolution In Situ Hybridization

mRNAs are frequently localized to vertebrate axons and their local translation is required for axon pathfinding or branching during development and for ...

detection-axonally-localized-mrnas-brain-sections-using-high

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11.7K vistas.  Columbia University. RNA in situ hybridization (ISH) enables the visualization of RNAs in cells and tissues. Here we show how combination of RNAscope ISH with immunohistochemistry or histological dyes can be successfully used to detect mRNAs localized to axons in sections of mouse and human brains.