Cellular and biochemical changes occurring during apoptosis of PC12 cells.

Format:

Book

Thesis/Dissertation

Author/Creator:

Messam, Conrad Alexander.

Contributor:

Pittman, Randall N., advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Biochemistry.

Cytology.

Neurosciences.

0317.

0379.

0487.

Penn dissertations--Pharmacology.

Pharmacology--Penn dissertations.

Local Subjects:

Penn dissertations--Pharmacology.

Pharmacology--Penn dissertations.

0317.

0379.

0487.

Physical Description:

128 pages

Contained In:

Dissertation Abstracts International 58-11B.

System Details:

Mode of access: World Wide Web.

text file

Summary:

The goal of this thesis project was to address several features of apoptosis that had not been investigated previously. These included: (1) defining the sequence of morphological changes accompanying apoptosis so that "morphological markers" can be used in future studies as reference points to place cellular and biochemical changes within a temporal sequence of events, (2) determining if all cells in a population undergo similar morphological changes during apoptosis, (3) determining at what point following an apoptotic stimulus cells commit to die, (4) determining if commitment to die can be defined relative to characteristic morphological changes, and (5) determining a role for intracellular Ca$\sp{2+}$ in modulating the execution phase of apoptosis in PC12 cells. Results from time lapse video microscopy experiments indicate that all cells in a population undergo similar and clearly defined morphological changes following an apoptotic stimulus even if they enter the execution phase of apoptosis more than 48 hrs apart. Since the sequence of morphological changes cells go through are stereotyped and very consistent from cell to cell, they can be used as reference points to place other cellular events. The point cells commit to die occurs 2-3 hrs prior to entering the execution phase of apoptosis. Video microscopy data indicate that apoptosis is an inherently asynchronous process even when daughter cells are synchronized following mitosis.

Measurement of intracellular free Ca$\sp{2+}$ in individual apoptotic cells showed a sustained elevation of Ca$\sp{2+}$ occurring 1-2 hrs before cells die. This increased intracellular free Ca$\sp{2+}$ correlates temporally with the onset of the execution phase. To determine if the rise in Ca$\sp{2+}$ affected processes in the execution phase, cells were transfected with the Ca$\sp{2+}$ binding protein, calbindin, or loaded with the Ca$\sp{2+}$ chelator, BAPTA. The execution phase appears to be a highly conserved feature of apoptosis; therefore, it is surprising that its length is considerably shorter in cells expressing calbindin or in cells loaded with BAPTA. Results obtained with calbindin expressing cells and BAPTA loaded cells are consistent with the length of the execution phase of apoptosis being regulated by intracellular free Ca$\sp{2+}.$

Notes:

Thesis (Ph.D. in Pharmacology) -- University of Pennsylvania, 1997.

Source: Dissertation Abstracts International, Volume: 58-11, Section: B, page: 5750.

Supervisor: Randall N. Pittman.

Local Notes:

School code: 0175.

ISBN:

9780591660234

Access Restriction:

Restricted for use by site license.