Mitosis and cytokinesis are undoubtedly the most spectacular parts of the cell cycle. Errors in the choreography of these processes can lead to aneuploidy or genetic instability, fostering cell death or disease. Here, I give an overview of the many mitotic kinases that regulate cell division and the fidelity of chromosome transmission.

Mitotic kinases as regulators of cell division and its checkpoints

A driving force of the cell cycle is the activation of cyclin-dependent kinases (CDKs), the activities of which are controlled by the ubiquitin-mediated proteolysis of key regulators such as cyclins and CDK inhibitors. Two ubiquitin ligases, the SKP1-CUL1-F-box-protein (SCF) complex and the anaphase-promoting complex/cyclosome (APC/C), are responsible for the specific ubiquitylation of many of these regulators. Deregulation of the proteolytic system might result in uncontrolled proliferation, genomic instability and cancer. Cumulative clinical evidence shows alterations in the ubiquitylation of cell-cycle regulators in the aetiology of many human malignancies. A better understanding of the ubiquitylation machinery will provide new insights into the regulatory biology of cell-cycle transitions and the development of anti-cancer drugs.

/pdf/ubiquitin-ligases-cell-cycle-control-and-cancer-38zd941ss3.pdf

Ubiquitin ligases: cell-cycle control and cancer

Cohesin complexes mediate sister-chromatid cohesion in dividing cells but may also contribute to gene regulation in postmitotic cells. How cohesin regulates gene expression is not known. Here we describe cohesin-binding sites in the human genome and show that most of these are associated with the CCCTC-binding factor (CTCF), a zinc-finger protein required for transcriptional insulation. CTCF is dispensable for cohesin loading onto DNA, but is needed to enrich cohesin at specific binding sites. Cohesin enables CTCF to insulate promoters from distant enhancers and controls transcription at the H19/IGF2 (insulin-like growth factor 2) locus. This role of cohesin seems to be independent of its role in cohesion. We propose that cohesin functions as a transcriptional insulator, and speculate that subtle deficiencies in this function contribute to 'cohesinopathies' such as Cornelia de Lange syndrome.

Cohesin mediates transcriptional insulation by CCCTC-binding factor

https://www.cell.com/molecular-cell/pdf/S1097-2765(02)00540-3.pdf

The anaphase-promoting complex: proteolysis in mitosis and beyond.

The cohesin complex is a major constituent of interphase and mitotic chromosomes. Apart from its role in mediating sister chromatid cohesion, it is also important for DNA double-strand-break repair and transcriptional control. The functions of cohesin are regulated by phosphorylation, acetylation, ATP hydrolysis, and site-specific proteolysis. Recent evidence suggests that cohesin acts as a novel topological device that traps chromosomal DNA within a large tripartite ring formed by its core subunits.

Cohesin: Its Roles and Mechanisms

https://www.andrew.cmu.edu/course/03-541/papers/P1.pdf

Cleavage of Cohesin by the CD Clan Protease Separin Triggers Anaphase in Yeast

The HCV NS5B polymerase, when complexed with certain inhibitors, adopts a confirmation in which the finger loop region defined by amino acid residues 18 to 35 is displaced to expose a binding pocket defined generally by amino acid residues 392, 393, 395, 396, 399, 424, 425, 428, 429, 492, 493, 494, 495, 496, 500 and 503. This newly exposed binding pocket defines a novel target in the search of further chemical entities which are capable of binding to HCV NS5B and modulating, or preferably inhibiting, the polymerase activity of HCV NS5B.

Hepatitis c virus ns5b polymerase inhibitor binding pocket

The present invention relates to racemates, diastereoisomers and optical isomers of tripeptides of general formula (I), pharmaceutically acceptable salts or esters thereof, pharmaceutical preparations containing the same, method for their production and intermediates. Furthermore, it relates to the use of the same for the preparation of a medicament for treating hepatitis C viral infection.

Tripeptides, method for their production, pharmaceutical preparation containing the same, their use and intermediates

In the present invention, there are disclosed racemates, diastereoisomers and optical isomers of a compound of the general formula I, wherein the individual symbols have specific meanings, or pharmaceutically acceptable salts or esters thereof. There is also disclosed the use of the compounds of the general formula I for preparing a medicament intended for the

Peptide inhibitors of hepatitis C virus

Racemates, diastereoisomers and optical isomers of a compound of formula (I): wherein B is H, a C 6 or C 10 aryl, C 7-16 aralkyl; Het or (lower alkyl)-Het, all of which optionally substituted with C 1-6 alkyl; C 1-6 alkoxy; C 1-6 alkanoyl; hydroxy; hydroxyalkyl; halo; haloalkyl; nitro; cyano; cyanoalkyl; amino optionally substituted with C 1-6 alkyl; amido; or (lower alkyl)amide; or B is an acyl derivative of formula R 4 -C(O)-; a carboxyl of formula R 4 -O-C(O)-; an amide of formula R 4 -N( R 5 )-C(O)-; a thioamide of formula R 4 -N( R 5 )-C(S)-;or a sulfonyl of formula R 4 -SO 2 ; R 5 is H or C 1-6 alkyl; and Y is H or C 1-6 alkyl; R 3 is C 1-8 alkyl, C 3-7 cycloalkyl, or C 4-10 alkylcycloalkyl, all optionally substituted with hydroxy, C 1-6 alkoxy, C 1-6 thioalkyl, amido, (lower alkyl)amido, C 6 or C 10 aryl, or C 7-16 aralkyl; R 2 is CH 2 - R 20 , NH- R 20 , O- R 20 or S- R 20 , wherein R 20 is a saturated or unsaturated C 3-7 cycloalkyl or C 4-10 (alkylcycloalkyl), all of which being optionally mono-, di- or trisubstituted with R 21 , or R 20 is a C 6 or C 10 aryl or C 7-14 aralkyl optionally substituted, or R 20 is Het or (lower alkyl)-Het, both optionally substituted, Het or (lower alkyl)-Het; carboxyl; carboxy(lower alkyl); C 6 or C 10 aryl, C 7-14 aralkyl or Het, said aryl, aralkyl or Het being optionally substituted; and R 1 is H; C 1-6 alkyl, C 3-7 cycloalkyl, C 2-6 alkenyl, or C 2-6 alkynyl, all optionally substituted with halogen; or a pharmaceutically acceptable salt or ester thereof.

Poupart Marc-Andre

Papers

Cleavage of Cohesin by the CD Clan Protease Separin Triggers Anaphase in Yeast

Hepatitis c virus ns5b polymerase inhibitor binding pocket

Tripeptides, method for their production, pharmaceutical preparation containing the same, their use and intermediates

Peptide inhibitors of hepatitis C virus

Hepatitis c tripeptide inhibitoren