MIWI N-terminal arginines orchestrate generation of functional pachytene piRNAs and spermiogenesis

N-terminal arginine (NTR) methylation is a conserved feature of PIWI proteins, which are central components of the PIWI-interacting RNA (piRNA) pathway. The significance and precise function of PIWI NTR methylation in mammals remains unknown. In mice, PIWI NTRs bind Tudor domain containing proteins (TDRDs) that have essential roles in piRNA biogenesis and the formation of the chromatoid body. Using mouse MIWI (PIWIL1) as paradigm, we demonstrate that the NTRs are essential for spermatogenesis through the regulation of transposons and gene expression. The loss of TDRD5 and TDRKH interaction with MIWI results in attenuation of piRNA amplification. We find that piRNA amplification is necessary for transposon control and for sustaining piRNA levels including select, nonconserved, pachytene piRNAs that target specific mRNAs required for spermatogenesis. Our findings support the notion that the vast majority of pachytene piRNAs are dispensable, acting as self-serving genetic elements that rely for propagation on MIWI piRNA amplification. MIWI-NTRs also mediate interactions with TDRD6 that are necessary for chromatoid body compaction. Furthermore, MIWI-NTRs promote stabilization of spermiogenic transcripts that drive nuclear compaction, which is essential for sperm formation. In summary, the NTRs underpin the diversification of MIWI protein function

Modulation of Aub-TDRD interactions elucidates piRNA amplification and germplasm formation.

Aub guided by piRNAs ensures genome integrity by cleaving retrotransposons, and genome propagation by trapping mRNAs to form the germplasm that instructs germ cell formation. Arginines at the N-terminus of Aub (Aub-NTRs) interact with Tudor and other Tudor domain-containing proteins (TDRDs). Aub-TDRD interactions suppress active retrotransposons via piRNA amplification and form germplasm via generation of Aub-Tudor ribonucleoproteins. Here, we show that Aub-NTRs are dispensable for primary piRNA biogenesis but essential for piRNA amplification and that their symmetric dimethylation is required for germplasm formation and germ cell specification but largely redundant for piRNA amplification

The Consciousness of Pain: A Thalamocortical Perspective

Deep, dreamless sleep is considered the only “normal” state under which consciousness is lost. The main reason for the voluntary, external induction of an unconscious state, via general anesthesia, is to silence the brain circuitry of nociception. In this article, I describe the perception of pain as a neural and behavioral correlate of consciousness. I briefly mention the brain areas and parameters that are connected to the presence of consciousness, mainly by virtue of their absence under deep anesthesia, and parallel those to brain areas responsible for the perception of pain. Activity in certain parts of the cortex and thalamus, and the interaction between them, will be the main focus of discussion as they represent a common ground that connects our general conscious state and our ability to sense the environment around us, including the painful stimuli. A plethora of correlative and causal evidence has been described thus far to explain the brain’s involvement in consciousness and nociception. Despite the great advancement in our current knowledge, the manifestation and true nature of the perception of pain, or any conscious experience, are far from being fully understood

Die Rolle von <i>Satb2</i>, <i>Ctip2</i> und Fezl in der kortikalen Konnektivität und die Aufklärung ihrer nachgeschalteten Signalwege

Satb2 hat sich als eine wesentliche postmitotische Determinante von Projektionsneuronen erwiesen (Alcamo et al., 2008; Britanova et al., 2008). Eine Möglichkeit für eine solche Funktion von Satb2 ist die Hemmung von Ctip2, einem Transkriptionsfaktor, der an im Tractus corticospinalis gelegenen Motoneuronen (CSMN) der Schicht V und anderen subzerebralen Projektionsneuronen innerhalb der tiefen Kortikalschichten (V und VI) exprimiert wird. In der vorliegenden Studie haben wir festgestellt, dass Unc5h3, ein Rezeptor der netrin-1 Signale abstößt und stark innerhalb der gesamten kortikalen Platte des Satb2-/- heruntergeregelt wird, eine wichtige Rolle bei der Führung von Axonen in die Mittellinie spielt. Unc5h3 wird hauptsächlich in callosalen Projektionsneuronen (Satb2+) exprimiert und weitgehend absent an subzerebralen Projektionsneuronen (Ctip2+) im neonatalen Mauskortex. Überexpression von Unc5h3 im Satb2-armen Neokortex führt zu einer partiellen Wiederherstellung callosaler Projektionen in einer stadiumspezifischen Weise (bei E12.5, nicht aber bei E14.5). Zudem resultiert die zusätzliche Beseitigung von Ctip2 aus dem Satb2-armen Kortex, welche durch die Herstellung von Satb2-/-;Ctip2-/- kombinierten Mutanten erreicht wird, zu einer Wiederaufnahme der Unc5h3 Expression und zu einer vergleichbaren partiellen Rettung von callosalen Projektionen. Vorausgesetzt, dass Satb2-arme Neuronen eine ektopische Überregulation von Ctip2 und einen Verlust von Unc5h3 zeigen, welcher nach der Beseitigung von Ctip2 wiederhergestellt wird, schlussfolgern wir, dass Ctip2 Unc5h3 hemmt. Diese Schlussfolgerung wird durch die Tatsache gestützt, dass Ctip2 in der Lage ist, an putativen Bindungsstellen von Unc5h3 Promoter-Regionen zu binden und dessen Expression in vivo und in vitrozu hemmen. Des Weiteren ist die Expression von DCC, einem weiteren netrin-1 Rezeptor, welcher netrin-1 Signale verarbeitet, in den oberflächlichen Kortexschichten sowohl von Satb2-/- als auch Satb2-/-;Ctip2-/- Mutanten überreguliert, was andeutet, dass Satb2 auf eine gewisse Weise die DCC Expression hemmt. Diese Überregulation kann, zumindest teilweise, das Fehlen einer vollständigen callosalen Wiederherstellung in den Satb2-/- sowohl aufgrund Unc5h3 Überexpression bei E12.5 (ein Zeitpunkt, in welchem tiefe und oberflächliche Schichten beeinflusst werden können), als auch aufgrund der zusätzlichen Beseitigung von Ctip2 (i.e. im Satb2-/-;Ctip2-/- erklären. Parallel haben wir den Effekt der Beseitigung von Satb2 in Fezl-/--Mäusen (Fezl ist ein Transkriptionsfaktor, der von CSMN und anderen subzerebralen Projektionsneuronen exprimiert wird) untersucht. Wir haben herausgefunden, dass im Gegensatz zu den Fez

Disruptions in asymmetric centrosome inheritance and WDR62-Aurora kinase B interactions in primary microcephaly

WOS: 000395685000001PubMed ID: 28272472Recessive mutations in WD repeat domain 62 (WDR62) cause microcephaly and a wide spectrum of severe brain malformations. Disruption of the mouse ortholog results in microcephaly underlain by reduced proliferation of neocortical progenitors during late neurogenesis, abnormalities in asymmetric centrosome inheritance leading to neuronal migration delays, and altered neuronal differentiation. Spindle pole localization of WDR62 and mitotic progression are defective in patient-derived fibroblasts, which, similar to mouse neocortical progenitors, transiently arrest at prometaphase. Expression of WDR62 is closely correlated with components of the chromosome passenger complex (CPC), a key regulator of mitosis. Wild type WDR62, but not disease-associated mutant forms, interacts with the CPC core enzyme Aurora kinase B and staining of CPC components at centromeres is altered in patient-derived fibroblasts. Our findings demonstrate critical and diverse functions of WDR62 in neocortical development and provide insight into the mechanisms by which its disruption leads to a plethora of structural abnormalities.NHGRI NIH HHS [U54 HG006504]; NICHD NIH HHS [R01 HD075822]; NCATS NIH HHS [UL1 TR001863

Disruptions in asymmetric centrosome inheritance and WDR62-Aurora kinase B interactions in primary microcephaly

Recessive mutations in WD repeat domain 62 (WDR62) cause microcephaly and a wide spectrum of severe brain malformations. Disruption of the mouse ortholog results in microcephaly underlain by reduced proliferation of neocortical progenitors during late neurogenesis, abnormalities in asymmetric centrosome inheritance leading to neuronal migration delays, and altered neuronal differentiation. Spindle pole localization of WDR62 and mitotic progression are defective in patient-derived fibroblasts, which, similar to mouse neocortical progenitors, transiently arrest at prometaphase. Expression of WDR62 is closely correlated with components of the chromosome passenger complex (CPC), a key regulator of mitosis. Wild type WDR62, but not disease-associated mutant forms, interacts with the CPC core enzyme Aurora kinase B and staining of CPC components at centromeres is altered in patient-derived fibroblasts. Our findings demonstrate critical and diverse functions of WDR62 in neocortical development and provide insight into the mechanisms by which its disruption leads to a plethora of structural abnormalities