Browsing by Subject "MOTILITY"

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  • Sakha, Prasanna; Vesikansa, Aino; Orav, Ester; Heikkinen, Joonas; Kukko-Lukjanov, Tiina-Kaisa; Shintyapina, Alexandra; Franssila, Sami; Jokinen, Ville; Huttunen, Henri J.; Lauri, Sari E. (2016)
    Kainate type of glutamate receptors (KARs) are highly expressed during early brain development and may influence refinement of the circuitry, via modulating synaptic transmission and plasticity. KARs are also localized to axons, however, their exact roles in regulating presynaptic processes remain controversial. Here, we have used a microfluidic chamber system allowing specific manipulation of KARs in presynaptic neurons to study their functions in synaptic development and function in vitro. Silencing expression of endogenous KARs resulted in lower density of synaptophysin immunopositive puncta in microfluidically isolated axons. Various recombinant KAR subunits and pharmacological compounds were used to dissect the mechanisms behind this effect. The calcium permeable (Q) variants of the low-affinity (GluK1-3) subunits robustly increased synaptophysin puncta in axons in a manner that was dependent on receptor activity and PKA and PKC dependent signaling. Further, an associated increase in the mean active zone length was observed in electron micrographs. Selective presynaptic expression of these subunits resulted in higher success rate of evoked EPSCs consistent with higher probability of glutamate release. In contrast, the calcium-impermeable (R) variant of GluK1 or the high-affinity subunits (GluK4,5) had no effect on synaptic density or transmission efficacy. These data suggest that calcium permeable axonal KARs promote efferent connectivity by increasing the density of functional presynaptic release sites.
  • Abdel-Rahman, Wael M.; Ruosaari, Saila; Knuutila, Sakari; Peltomäki, Päivi T (2012)
  • Maes, Alexandre; Gracia, Celine; Innocenti, Nicolas; Zhang, Kaiyang; Aurell, Erik; Hajnsdorf, Eliane (2017)
    Polyadenylation is thought to be involved in the degradation and quality control of bacterial RNAs but relatively few examples have been investigated. We used a combination of 5 '-tagRACE and RNA-seq to analyze the total RNA content from a wild-type strain and from a poly(A) polymerase deleted Mutant. A total of 178 transcripts were either up- or down-regulated in the mutant when compared to the wild-type strain. Poly(A) polymerase up-regulates the expression of all genes related to the FliA regulon and several previously unknown transcripts, including numerous transporters. Notable down-regulation of genes in the expression of antigen 43 and components of the type 1 fimbriae was detected. The major consequence of the absence of poly(A) polymerase was the accumulation of numerous sRNAs, antisense transcripts, REP sequences and RNA fragments resulting from the processing of entire transcripts. A new algorithm to analyze the position and composition of post-transcriptional modifications based on the sequence of unencoded 3 '-ends, was developed to identify polyadenylated molecules. Overall our results shed new light on the broad spectrum of action of polyadenylation on gene expression and demonstrate the importance of poly(A) dependent degradation to remove structured RNA fragments.
  • Nevalainen, Elisa M.; Braun, Attila; Vartiainen, Maria K.; Serlachius, Martina; Andersson, Leif C.; Moser, Markus; Lappalainen, Pekka (2011)