28.06.2014 Views

Modern - Blog Science Connections

Modern - Blog Science Connections

Modern - Blog Science Connections

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

and nonhistone proteins can serve as acceptors.<br />

Recent data suggest that poly ADP<br />

ribosylation of pro tein is involved in DNA<br />

repair processes while modification by mono<br />

(ADP-ribose )-residues of nuclear proteins appears<br />

to be involved in the maintenance of<br />

cellular differentiation (Juarez-Salinas et al.<br />

1979; Hilz et al. 1980). Therefore, quantitati<br />

on of mono (ADP-ribose)-protein conjugates<br />

was of special interest. Using a sensitive<br />

radioimmunological procedure, two types of<br />

mono(ADP-ribose) protein conjugates could<br />

be determined that differ in their sensitivity<br />

towards neutral NH 2 0H. From analyses in the<br />

cell cycle (Wie1ckens et al. 1979), it had<br />

become evident that the two subfractions of<br />

the mono(ADP-ribose )-conjugates are independently<br />

synthesized and therefore may serve<br />

independent functions in the chromatin. Determination<br />

of these conjugates in differentiating<br />

Dictyostelium discoideum (Bredehorst et<br />

al. 1980) and during liver development (Hilz et<br />

al. 1980) had indicated that it is primarily the<br />

subfraction of the NH 2 0H resistant mono­<br />

(ADP-ribose)-conjugates that correlated with<br />

the degree of (normal) differentiation.<br />

When normal and leukemic lymphocytes<br />

were analyzed for the extent of protein modification<br />

by mono(ADP-ribose )-residues, a marked<br />

reduction was noticed in the chronic<br />

400<br />

CHEMOTHERAPY<br />

, 5.<br />

2.0<br />

;2 300<br />

t:l<br />

(!)<br />

~<br />

"­<br />

...J<br />

o<br />

~<br />

a..<br />

(/)<br />

UJ<br />

=><br />

t:l<br />

(/)<br />

~ 200<br />

------." "­,<br />

LEUKOCYTE COUNT "-,,-<br />

,<br />

- ,<br />

"­ "­ ,<br />

'.<br />

.......<br />

1.5<br />

1.0<br />

r<br />

ITI<br />

c:<br />

" o<br />

n<br />

-<<br />

-4<br />

ITI<br />

n<br />

o<br />

c<br />

:z<br />

-4<br />

x<br />

....... ....... , ,<br />

"- "­<br />

7.<br />

100<br />

0.5<br />

MONO(ADPR) RESIDUES<br />

1. 3.<br />

5.<br />

9.<br />

WEEK<br />

Fig. 2. Time course of ADP ribosylation under combination chemotherapy with chlorambucil/prednisone.<br />

Data from one patient with CLL. For experimental details see Wielckens et al. (1980)<br />

227

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!