Communication between distinct subunit interfaces of the cohesin complex promotes its topological entrapment of DNA.

Cohesin mediates higher order chromosome structure. Its biological activities require topological entrapment of DNA within a lumen(s) formed by cohesin subunits. The reversible dissociation of cohesins Smc3p and Mcd1p subunits is postulated to form a regulated gate that allows DNA entry and exit into the lumen. We assessed gate-independent functions of this interface in yeast using a fusion protein that joins Smc3p to Mcd1p. We show that in vivo all the regulators of cohesin promote DNA binding of cohesin by mechanisms independent of opening this gate. Furthermore, we show that this interface has a gate-independent activity essential for cohesin to bind chromosomes. We propose that this interface regulates DNA entrapment by controlling the opening and closing of one or more distal interfaces formed by cohesin subunits, likely by inducing a conformation change in cohesin. Furthermore, cohesin regulators modulate the interface to control both DNA entrapment and cohesin functions after DNA binding

A novel mechanism for the establishment of sister chromatid cohesion by the ECO1 acetyltransferase

Cohesin complex mediates cohesion between sister chromatids, which promotes high-fidelity chromosome segregation. Eco1p acetylates the cohesin subunit Smc3p during S phase to establish cohesion. The current model posits that this Eco1p-mediated acetylation promotes establishment by abrogating the ability of Wpl1p to destabilize cohesin binding to chromosomes. Here we present data from budding yeast that is incompatible with this Wpl1p-centric model. Two independent in vivo assays show that a wpl1∆ fails to suppress cohesion defects of eco1∆ cells. Moreover, a wpl1∆ also fails to suppress cohesion defects engendered by blocking just the essential Eco1p acetylation sites on Smc3p (K112, K113). Thus removing WPL1 inhibition is insufficient for generating cohesion without ECO1 activity. To elucidate how ECO1 promotes cohesion, we conducted a genetic screen and identified a cohesion activator mutation in the SMC3 head domain (D1189H). Smc3-D1189H partially restores cohesion in eco1∆ wpl1∆ or eco1 mutant cells but robustly restores cohesion in cells blocked for Smc3p K112 K113 acetylation. These data support two important conclusions. First, acetylation of the K112 K113 region by Eco1p promotes cohesion establishment by altering Smc3p head function independent of its ability to antagonize Wpl1p. Second, Eco1p targets other than Smc3p K112 K113 are necessary for efficient establishment.National Institutes of Health (U.S.) (Grant R01GM092813

Epoetin alfa increases frataxin production in Friedreich's ataxia without affecting hematocrit.

Objective of the study was to test the efficacy, safety, and tolerability of two single doses of Epoetin alfa in patients with Friedreich's ataxia. Ten patients were treated subcutaneously with 600 IU/kg for the first dose, and 3 months later with 1200 IU/kg. Epoetin alfa had no acute effect on frataxin, whereas a delayed and sustained increase in frataxin was evident at 3 months after the first dose (+35%; P < 0.05), and up to 6 months after the second dose (+54%; P < 0.001). The treatment was well tolerated and did not affect hematocrit, cardiac function, and neurological scale. Single high dose of Epoetin alfa can produce a considerably larger and sustained effect when compared with low doses and repeated administration schemes previously adopted. In addition, no hemoglobin increase was observed, and none of our patients required phlebotomy, indicating lack of erythropoietic effect of single high dose of erythropoietin. © 2010 Movement Disorder Society

Chromosomal Addresses of the Cohesin Component Mcd1p

We identified the chromosomal addresses of a cohesin subunit, Mcd1p, in vivo by chromatin immunoprecipitation coupled with high resolution PCR-based chromosomal walking. The mapping of new Mcd1p-binding sites (cohesin-associated regions [CARs]) in single-copy sequences of several chromosomes establish their spacing (∼9 kb), their sequestration to intergenic regions, and their association with AT-rich sequences as general genomic properties of CARs. We show that cohesins are not excluded from telomere proximal regions, and the enrichment of cohesins at the centromere at mitosis reflects de novo loading. The average size of a CAR is 0.8–1.0 kb. They lie at the boundaries of transcriptionally silenced regions, suggesting they play a direct role in defining the silent chromatin domain. Finally, we identify CARs in tandem (rDNA) and interspersed repetitive DNA (Ty2 and subtelomeric repeats). Each 9-kb rDNA repeat has a single CAR proximal to the 5S gene. Thus, the periodicity of CARs in single-copy regions and the rDNA repeats is conserved. The presence and spacing of CARs in repetitive DNA has important implications for genomic stability and chromosome packaging/condensation

Pds5 is required for homologue pairing and inhibits synapsis of sister chromatids during yeast meiosis

A meiosis-conditional pds5 allele in yeast provides a more detailed understanding of homologue pairing and synaptonemal complex formation

Le impugnazioni incidentali nel processo amministrativo italiano

The article number 96 of the code of civil procedure governs the incidental objections, accepting them to the judicial review, the new trial, the examination pro interesse suo, and, in certain events, the petition to the Highest Court. The appeal has to be proposed by the service of the process adjudication and cross-examination receivers under the vest of an incidental form, otherwise it will run the risk of lapse. The relationship of conditioning-dependence between the main and the incidental appeals can be considered either in the case of a proper than of an untimely incidental appeal. The need to strictly apply the principle of the appeals concentration has oriented the legislator to decree the receivability of the incidental appeal also in case of autonomous judgement charges. L’istituto dell’impugnazione incidentale costituisce applicazione del principio di concentrazione delle impugnazioni. L’art. 96 c.p.a. disciplina le impugnazioni incidentali, ammettendole per l’appello, per la revocazione, per l’opposizione di terzo e, con qualche particolarità, per il ricorso per cassazione. L’impugnazione va proposta in forma incidentale, a pena di decadenza, dai destinatari della notifica della sentenza e dell’atto di integrazione del contraddittorio. Il rapporto di condizionalità-dipendenza, fra impugnazione principale e impugnazione incidentale, sussiste sia nel caso di impugnazione incidentale propria, sia nel caso di impugnazione incidentale tardiva. L’esigenza di applicare in maniera rigorosa il principio di concentrazione delle impugnazioni ha indotto il legislatore a sancire l’ammissibilità dell’impugnazione incidentale anche avverso capi autonomi della sentenza.The article number 96 of the code of civil procedure governs the incidental objections, accepting them to the judicial review, the new trial, the examination pro interesse suo, and, in certain events, the petition to the Highest Court. The appeal has to be proposed by the service of the process adjudication and cross-examination receivers under the vest of an incidental form, otherwise it will run the risk of lapse. The relationship of conditioning-dependence between the main and the incidental appeals can be considered either in the case of a proper than of an untimely incidental appeal. The need to strictly apply the principle of the appeals concentration has oriented the legislator to decree the receivability of the incidental appeal also in case of autonomous judgement charges