Apoptosis - Programmed Cell Death

Tijekom evolucije višestanični organizmi uspjeli su razviti različite mehanizme zaštite od djelovanja štetnih utjecaja iz okoline. Apoptoza ili “programirana smrt stanice” jedan je od tih mehanizama kojim stanica aktivno uz utrošak energije i sintezu određenih proteina pokreće vlastitu smrt kao sastavni dio fizioloških procesa ili kao odgovor na određena patološka stanja. Poremećaji u apoptozi vezani su uz mnogobrojne bolesti jer nefunkcionalne, mutirane ili na bilo koji način oštećene stanice koje izmaknu kontrolnim mehanizmima i koje ne obavljaju svoju fiziološku funkciju, mogu dovesti do pojave teških bolesti. Stoga je pravilan tijek apoptotskih procesa ključan za pravilan embrionalni razvoj i za pravilno održavanje stanične homeostaze tkiva. Centralno je mjesto apoptoze proenzimska skupina cisteinskih proteaza u citoplazmi stanica. Kaskadna aktivacija tih proteaza ključna je u genezi morfoloških i biokemijskih apoptotskih promjena. Do danas je već poznat velik broj vanjskih i unutarnjih faktora koji dovode do pojave apoptoze. Poznavanje tih faktora i puno razumijevanje mehanizama apoptotskih procesa otvara potpuno nove mogućnosti u liječenju nekih teških, zasad neizlječivih bolesti.During the evolution, multi-cellular organisms have developed various protective mechanisms against environmental insults. Apoptosis is one of physiological mechanisms where in fact a cell itself actively induces its own death. In contrast to necrosis where the cell death occurs usually as a result of severe physical or chemical extra cellular factors accompanied by inflammatory reactions of tissue, the apoptotic process starts without signs and symptoms of inflammation, and generally starts from the inside of the cell, involving the use of energy and active synthesis of specific proteins. Apoptosis is important for the right balance between the loss of old, non-functional cells and the formation of new ones in certain organs and tissues. In adition, it is a specific answer of an organism to a number of pathological conditions. Thus apoptosis plays a very important role both in physiologic and pathologic processes in the body throughout the life of an organism. A normal development of embryo and foetus is impossible without a very intensive apoptotic process. The dysfunction of the apoptotic mechanism is associated with a number of diseases in humans and animals. The apoptosis starts by triggering different intra- and intercellular signals and stimulations, which involve a number of extrinsic or intrinsic apoptotic pathways resulting in caspase cascade activation. Caspases belongs to the family of cisteine proteases, and have a central role in facilitating a number of morphological and biochemical changes during the programmed cell death. The understanding of these complex pathways offers new approaches to clinical treatment of fatal human diseases. The promising possibilities of application of the knowledge about the mechanism of apoptosis in the treatment of human diseases make the research in this field challenging and exciting

Detection Apoptosis

Apoptoza ili programirana smrt stanice ima vodeću ulogu u mnogim biološkim procesima. Njezino određivanje od velike je važnosti u različitim područjima moderne biologije, uključujući različite studije o embrionalnom razvoju, biologiji tumora te brojnim degenerativnim i imunodeficijentnim bolestima koje se povezuju s poremećajima u apoptozi. Mehanizam aktivacije i pokretanja apoptotskog procesa vrlo je kompleksan i prate ga specifične morfološke i biokemijske promjene stanica, koje često variraju ovisno o tipu stanica i specifičnim uvjetima okoline u kojoj rastu. Upravo zbog tog razloga bitno je upotrijebiti više različitih detekcijskih metoda koje će obuhvatiti različite stadije apoptoze kako bi se izbjegli lažno pozitivni ili lažno negativni rezultati. Svaka od danas poznatih i upotrebljavanih metoda ima svoje prednosti i nedostatke te ni za jednu od njih ne možemo reći da potpuno zadovoljava sve kriterije. U ovom radu prikazan je kratak pregled metoda koje se najčešće rabe pri detekciji apoptoza te osnovni morfološki i biokemijski procesi na kojima se te metode zasnivaju.Apoptosis or programmed cell death is the most important process in a huge number of biological processes. Its detection is very important for different fields of modern biology including embryonic development, tumour biology and numerous degenerative and immunodeficiency syndromes associated with apoptotic disorders. The mechanism of apoptosis activation is very complex and accompanied by specific morphological and biochemical cell changes that differ depending on the cell type and conditions in which the cell grows. For this reason it is essential to use several methods to detect different steps of apoptosis and thus avoid false positive or false negative results. All known and used methods have some advantages and disadvantages, but none completely meets the desired conditions. This short review presents the methods most frequently used to detect apoptosis and the biological and biochemical processes which provide the bases for these methods

Renal expression of organic anion transporter Oat5 in rats and mice exhibits the female-dominant sex differences

The organic anion transporter 5 (Oat5, Slc22a19) was previously localized to the brush-border of proximal tubule (PT) S3 segment in rat and mouse kidneys. Here we report on sex hormone-regulated expression of Oat5 in rat kidneys, after reinvestigating: a) expression of its mRNA by end-point and real time RT-PCR in the tissue, b) abundance of its protein by Western blotting (WB) in isolated membranes, and c) immunolocalization in tissue cryosections. In untreated male (M) and female (F) adult rats, the expression of Oat5 mRNA was predominant in the outer stripe (OS), exhibiting sex differences (M<F), upregulated by castration, and unaffected by ovariectomy. In castrated M, testosterone treatment strongly downregulated, whereas estradiol and progesterone treatment weakly upregulated its expression. By WB, a single protein band of ~72 kDa in variously-treated animals exhibited a density pattern comparable to that of mRNA. By immunostaining, Oat5 protein was localized to the brush-border of S1/S2 in the cortex (CO) (weakly) and in S3 of the OS and medullary rays (strongly) with the F-dominant intensity. In variously-treated rats, the immunostaining pattern matched that of mRNA and WB data. In prepubertal rats, the renal expression of Oat5 mRNA and protein was weak and sex-independent. In adult mice, the sex-dependent pattern of renal Oat5 protein expression was comparable to that in rats. Therefore, the renal expression of Oat5 in rats (and mice) exhibits zonal (CO<OS) and sex differences (M<F), which appear after puberty, largely due to androgen-driven downregulation of its mRNA and protein expression