Increased Stress-Activated Protein Kinase Astivity During PGF2alpha Mediated Apoptotic Cell Death in Buffalo Corpus Luteum

Yadav, Vijay K and Natrajan, T and Medhamurthy, R (2001) Increased Stress-Activated Protein Kinase Astivity During PGF2alpha Mediated Apoptotic Cell Death in Buffalo Corpus Luteum. In: XXV All India Cell Biology Conference, Bangalore, A 59.

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Abstract

Corpus luteum (CL) is a transient endocrine structure which develops from the remains of the Graffian follicle after ovulation in mammals. Prolongation of its function is required during pregnancy, while cessation of its function is a must for the initiation of a new reproductive cycle. In a number of farm animals including the bovine species, Prostaglandin F2a (PGF2a) is recognized as a physiological death signal/luteolysin for the regression of the corpus luteum. Despite the central role played by PGF2a in luteolysis, actual mechanisms during luteolysis are poorly defined. However, it is well established that regression of CL by PGF2a is brought about by the process of apoptosis. In the present study, CL from buffaloes (Bubalus bubalis) has been employed to examine whether PGF2a induces regression of CL by apoptosis as previously reported for the CL of dairy cow (Bos taurus). Also, the role played by the members belonging to the superfamily of mitogen activated protein kinases (MAPK) during luteal regression was investigated, since MAPK have been shown to play a very important role during growth, differentiation and cell death. Individual CL was collected from the buffaloes at 0, 4, 12 and 18 h after injection of luteolyzing dose of PGF2a and the CL was processed for morphological and biochemical characterization of the apoptosis. Administration of PGF2a to buffalo cows lead to a precipitous fall in serum progesterone concentrations within 4 h and the decrease was maximal by 18 h. DAPI staining of cryosections of the CL tissue collected 18 h post PGF2a injection showed increased nuclear condensation and loss of nuclei in some of the cells. To quantitate low molecular weight (LMW) DNA fragments, genomic DNA was end labeled using [a-32P] dATP by tdt enzyme. There was a 3-4 fold increase in the LMW DNA fragments 18 h post PGF2a injection. Western blot analysis of the CL tissue lysates was carried out for assessing the role played by MAP kinases and apoptotic factors during the PGF2a-induced luteolysis. There was a significant increase in the phospho-JNK levels (the active form of JNK), a decrease in the pBAD levels (the inactive form of BAD) and no change in the p38 MAPK, ERK1/2, JNK1/2, BAD and PP2A levels during the PGF2a-induced luteolysis. These results demonstrate that similar to the dairy cow CL, the buffalo CL undergoes apoptotic cell death during PGF2a-induced luteolysis and provide evidence that stress-activated protein kinases appear to be involved in the PGF2a-induced apoptosis of luteal cells.

Item Type:	Conference Poster
Keywords:	Corpus Luteum
Department/Centre:	Division of Biological Sciences > Molecular Reproduction, Development & Genetics
Date Deposited:	04 Sep 2004
Last Modified:	16 Jan 2013 11:42
URI:	http://eprints.iisc.ac.in/id/eprint/145

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