The E705K Mutation in hPMS2 Exerts Recessive, Not Dominant, Effects on Mismatch Repair

The hPMS2 mutation E705K is associated with Turcot syndrome. To elucidate the pathogenesis of hPMS2-E705K, we modeled this mutation in yeast and characterized its expression and effects on mutation avoidance in mammalian cells. We found that while hPMS2-E705K (pms1-E738K in yeast) did not significantly affect hPMS2 (Pms1p in yeast) stability or interaction with MLH1, it could not complement the mutator phenotype in MMR-deficient mouse or yeast cells. Furthermore, hPMS2-E705K/pms1-E738K inhibited MMR in wild-type (WT) mammalian cell extracts or yeast cells only when present in excess amounts relative to WT PMS2. Our results strongly suggest that hPMS2-E705K is a recessive loss-of-function allele

Identification of spindle complexes in the cranial muscles.

<p><b>(a)</b> A spindle complex located in the masseter that is labeled by anti-Neurofilament H (green) with the nuclei in the underlying muscle labeled with DAPI (grey) at three imaging depths. Two nuclear bag fibers, labeled 1 and 4, and two chain fibers, labeled 2 and 3, form this complex. <b>(b,c)</b> Spindle sensory afferent fibers labeled by anti-Neurofilament H in the masseter (panel b) and the mystacial pad muscles (panel c). The muscle is stained with cytochrome oxidase (brown). <b>(d)</b> Fraction of labeled spindles relative to the number of labeled endplates in the same section, together with the fraction of observed intrafusal fibers per extrafusal fiber in the same section. <b>(e,f)</b>. Transverse sections of masseter (panel e) and mystacial pad (panel f), stained with hematoxylin and eosin stain to highlight all muscle fibers, together with higher magnification images that highlight intrafusal fibers (arrows). The raw data for panels b through f are in supplemental information <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002253#pbio.1002253.s001" target="_blank">S1 Data</a>.</p

Identification of alpha and gamma motoneurons that innervate cranial muscles.

<p><b>(a)</b> Rat brainstem section containing trigeminal and lateral facial motor nuclei. The section is labeled with anti-ChAT (green) anti-NeuN (red) and DAPI (blue). <b>(b)</b> Sample outlines of motoneurons in the trigeminal and lateral facial motor nuclei based on anti-ChAT labeling. <b>(c)</b> anti-ChAT labeling of motoneurons in the trigeminal motor nucleus. <b>(d)</b> anti-NeuN labeling of the neurons in <b>panel c</b>. <b>(e)</b> anti-ChAT and anti-NeuN labeling of the neurons in <b>panel c. (f)</b> anti-ChAT labeling of motoneurons in the facial motor nucleus. <b>(g)</b> anti-NeuN labeling of the neurons in <b>panel f</b>. <b>(h)</b> anti-ChAT and anti-NeuN labeling of the neurons in <b>panel f. (i)</b> Luminance of anti-NeuN label versus area of anti-ChAT label for trigeminal motoneurons in three rats. <b>(j)</b> Luminance of anti-NeuN label versus area of anti-ChAT label for facial motoneurons in three rats. <b>(k)</b> Histograms of the first principal component of log(Luminance) and log(Area) for the trigeminal motoneurons in <b>panel i. (l)</b> Histograms of the first principal component of log(Luminance) and log(Area) for the facial motoneurons in <b>panel j.</b> The raw data for panels i and j are in supplemental information <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002253#pbio.1002253.s002" target="_blank">S2 Data</a> and that for panels k and l are in supplemental information <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002253#pbio.1002253.s003" target="_blank">S3 Data</a>.</p

Schemes for demodulation of touch signals by vibrissa whisking signals.

<p><b>(a)</b> A scheme for a parallel pathway for the ex-afferent signal and a reafferent signal that encodes phase in the whisk cycle independent of touch to the vibrissae. The slope of the f-I curve is assumed to be modulated by the reafferent signal, as can occur if re-afference drives shunting inhibition. This scheme is relevant if the encoding of whisking by the skin and fur serves as the reafferent signal. <b>(b)</b> A scheme for a single pathway for both the ex-afferent signal, which encodes touch to the vibrissa, and re-afferent signal, which encodes phase in the whisk cycle, measured in terms of free whisking in air. The signals are mixed by a spike rate versus input current (f-I) function that has an accelerating slope. This scheme is relevant if both the ex-afferent and re-afferent input share the same ascending lemniscal input from VPM to layer 4 cortical neurons.</p

Spiking responses of additional VPM and PO thalamic and ZIv neurons to whisking in air.

<p><b>(a)</b> Spike rate versus phase in the whisk cycle (blue histogram, left) and sinusoidal fit (red, right). Multi-unit activity at the same recording site was elicited in response to deflections vibrissa A2. The recording site was identified in VPM thalamus in post-hoc histology (right). <b>(b)</b> Spike rate versus phase in the whisk cycle and sinusoidal fit for a unit located in VPM thalamus. The unit was located among units that responded to brushing the naris (right). <b>(c)</b> Spike rate versus phase in the whisk cycle and sinusoidal fit for a unit located in PO thalamus. <b>(d)</b> Spike rate versus phase in the whisk cycle and sinusoidal fit for a unit located in ZIv. <b>(e)</b> Mean spike rates during whisking and non-whisking epochs for all VPM thalamic (blue and cyan), PO thalamic (green), and ZIv (red) neurons in this study. VPM neurons that have macrovibrissa receptive fields (blue), as well as those that have facial skin, fur, or micro-vibrissa receptive fields (cyan) are shown. Solid symbols correspond to statistically significant modulation and open symbols to non-significant modulation (Kuiper test, <i>p</i> < 0.05). The raw data for panel e are in supplemental information <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002253#pbio.1002253.s005" target="_blank">S5 Data</a>.</p

Modulation of spiking activity with free-air whisking in the trigeminal nuclei.

<p><b>(a)</b> Whisking modulation, M_Whisk, versus mean spike rate for all units, using the notation of <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002253#pbio.1002253.g005" target="_blank">Fig 5d</a>. Contours with constant value of SNR_Whisk are shown as dashed lines for a temporal window of 165 ms. Approximate receptive fields at the recording sites are labeled. <b>(b)</b> Plot of the preferred phase (polar axis) versus SNR_Whisk (radial axis) for all trigeminal units. The raw data for panels a and b are in supplemental information <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002253#pbio.1002253.s004" target="_blank">S4 Data</a>.</p

Spiking responses of units in nucleus PrV and SpVIr to free-air whisking.

<p><b>(a)</b> Spike rate versus phase in the whisk cycle (blue histogram, left) and sinusoidal fit (red, left) of a unit in nucleus PrV. Multi-unit activity at the same recording site was elicited in response to deflections of vibrissa B1 (right). <b>(b)</b> Same as <b>panel a</b>, but for a unit in nucleus PrV that is located among units that responded to brushing the fur on the upper lip. <b>(c)</b> Spike rate versus phase in the whisk cycle (blue histogram, left) and sinusoidal fit (red, left) for a unit in nucleus SpVIr. Location of the recording site in a horizontal brainstem section (right). <b>(d)</b> Mean spike rates during whisking and non-whisking epochs for all putative single-unit (circles) and multi-unit (squares) recordings in nuclei SpVIr (green) and PrV (blue and cyan). PrV units that have macrovibrissa receptive fields (blue), as well as those that have facial skin, fur, or micro-vibrissa receptive fields (cyan) are shown. Of all of these trigeminal units, 49/56 units across three rats in nucleus PrV and 16/24 units across three rats in nucleus SpVIr were significantly modulated (Kuiper test, <i>p</i> < 0.05); solid symbols correspond to statistically significant modulation and open symbols to non-significant modulation. The raw data for panel d are in supplemental information <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002253#pbio.1002253.s004" target="_blank">S4 Data</a>.</p

Map of vibrissa ascending pathways from the periphery to cortex.

<p>Dashed arrows represent individual barrelettes, barreloids, and barrels. The classical lemniscal pathway, including neurons with single- and multi-vibrissae receptive fields through the head and core of the barreloids, respectively, is shown in blue. The paralemniscal pathway is shown in green, and a third, extralemniscal pathway in grey. Inhibitory interactions are shown in black. Abbreviations: PrV, principal trigeminal nucleus; SpVIr and SpVIc, rostral and caudal divisions of spinal nucleus interpolaris, respectively; SpVM, spinal nucleus muralis; SpVC, spinal nucleus caudalis; VPMdm, dorsomedial aspect of the ventral posterior medial nucleus of dorsal thalamus; PO, medial division of the posterior group nucleus; nRt, nucleus reticularis; and ZIv, ventral aspect of the zona incerta. An original figure constructed with elements from Fig 3 in reference [<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002253#pbio.1002253.ref019" target="_blank">19</a>] and data from reference [<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002253#pbio.1002253.ref041" target="_blank">41</a>] to define the trigeminal borders.</p

Compendium on modulation of spiking by free-air whisking by units in the thalamus and zona incerta.

<p>Modulation depth, M_Whisk, versus mean spike rate for individual neurons in VPM, PO, and ZIv. Conventions are as in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002253#pbio.1002253.g008" target="_blank">Fig 8e</a>. Contours with constant values of SNR_Whisk are shown as dashed lines, and approximate receptive fields at the recording sites are labeled. <b>(b)</b> Plot of the preferred phase (polar axis) versus SNR_Whisk (radial axis) for the units in panel a. <b>(c)</b> The value of SNR_Whisk versus perpendicular distance to the VPM/PO border for the labeled VPM and PO recording sites in panel a. The values of SNR_Whisk for neurons in ZIv are shown at the right end (red). <b>(d)</b> Rostral view of the reconstructed locations of recording sites (circles) and select anatomical borders in three dimensions. The colors of the circles represent the SNR_Whisk for each recorded neuron; gray corresponds to neurons that were not significantly modulated by whisking phase. Labeled structures correspond to the third ventricle (3v, yellow), habenula (Hb, teal), mammothalamic tract (mt, gray), thalamic reticular nucleus (Rt, blue), and ventral division of zona incerta (ZIv, green). The anatomical axes are shown in the lower right hand corner: dorsal (D), medial (M), and caudal (C). <b>(e)</b> An oblique view of the reconstruction in panel d. The raw data for panels a through c are in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002253#pbio.1002253.s004" target="_blank">S4 Data</a>.</p