Document Detail

Immunohistochemical analysis of the proapoptotic protein Par-4 in normal rat tissues.
MedLine Citation:
PMID:  9269897     Owner:  NLM     Status:  MEDLINE    
Prostate apoptosis response 4 (par-4) is a recently identified gene that encodes a transcription factor, Par-4, with a leucine zipper domain. Par-4 protein is constitutively expressed in various cell lines and is functionally required but not sufficient for apoptosis. Induction of Par-4 in cultured cells is found exclusively during apoptosis, and ectopic overexpression of Par-4 enhances the potency of apoptotic stimuli. Western or Northern blot analysis on mRNA or protein extracts, respectively, from rat organs revealed that the expression of Par-4 was ubiquitous and was not restricted to any specific organ(s). To further identify specific cell types that expressed Par-4, we performed an immunohistochemical analysis of the protein in paraffin-embedded sections of various organs from rats. Our findings indicated that consistent with its proapoptotic role, Par-4 is expressed in apoptotic granulosa cells of atretic ovarian follicles and in terminally differentiated cells, such as the cardiomyocytes, cerebellar Purkinje cells, and pyramidal cells of the hypothalamus. Moreover, testosterone ablation by castration of rats caused an early and transient induction of Par-4 in the ductal cells of the prostate that undergo apoptosis. By contrast, in tissues in which the cells could be visually differentiated from their mature counterparts, Par-4 expression was lowest in the mature cells. This was the case for epithelia of the mammary and the prostate gland in which the basal cells maintained higher protein levels of Par-4 than did the terminally differentiated ductal cells. Similarly, cells of the stratum corneum of the skin and cells on top of the duodenal villi stained less intensely for Par-4 as compared to the stem cells in the stratum basale and at the bottom of the crypts of Lieberkühn, respectively. It is possible that Par-4 has to be down-regulated for successful differentiation in these tissues. Taken together, the widespread expression of Par-4 in various adult cell types underscores the physiological importance of the protein. The observation of constitutive Par-4 expression in the stem cell compartments is inconsistent with the probability of apoptosis per se and can be extended to determine whether Par-4 plays a role in other cellular processes.
E R Boghaert; S F Sells; A J Walid; P Malone; N M Williams; M H Weinstein; R Strange; V M Rangnekar
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Cell growth & differentiation : the molecular biology journal of the American Association for Cancer Research     Volume:  8     ISSN:  1044-9523     ISO Abbreviation:  Cell Growth Differ.     Publication Date:  1997 Aug 
Date Detail:
Created Date:  1997-09-24     Completed Date:  1997-09-24     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  9100024     Medline TA:  Cell Growth Differ     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  881-90     Citation Subset:  IM    
Department of Surgery, University of Kentucky, Lexington 40536, USA.
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MeSH Terms
Apoptosis / physiology*
Apoptosis Regulatory Proteins
Carrier Proteins / analysis*,  genetics
Endothelium / chemistry
Epithelium / chemistry
Gene Expression Regulation, Developmental
Intracellular Signaling Peptides and Proteins*
Mammary Glands, Animal / chemistry
Organ Specificity
Ovary / chemistry,  cytology
Prostate / chemistry
RNA, Messenger / analysis
Rats, Sprague-Dawley
Testosterone / physiology
Grant Support
Reg. No./Substance:
0/Apoptosis Regulatory Proteins; 0/Carrier Proteins; 0/Intracellular Signaling Peptides and Proteins; 0/RNA, Messenger; 0/prostate apoptosis response-4 protein; 58-22-0/Testosterone

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