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Developmental expression of protein kinase C subspecies in rat brain-pituitary axis
S Garcia-Navarro1, Y Marantz, R Eyal
1Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel.
Insights
Neonatal brain protein kinase C (PKC) activity significantly increases during the first week of life. Pituitary PKC activity decreases with age, despite a rise in PKC-labeled cells, indicating complex developmental regulation.
Area of Science:
- Neuroscience
- Developmental Biology
- Molecular Biology
Background:
- Protein Kinase C (PKC) plays crucial roles in cellular signaling.
- Understanding PKC subspecies expression during development is vital for comprehending neural and endocrine maturation.
Purpose of the Study:
- To investigate the neonatal developmental expression patterns of various protein kinase C (PKC) subspecies in rat brain and pituitary glands.
- To elucidate the differential regulation of PKC subspecies in these tissues during early life.
Main Methods:
- Enzymatic activity assays were performed to quantify PKC activity.
- Immunohistochemistry was used to assess the cellular localization and abundance of PKC.
- Western blot analysis with type-specific antibodies identified and quantified specific PKC subspecies.
Main Results:
- Rat brain PKC activity showed a substantial increase (455%) in the first week, with particulate fraction activity rising dramatically.
- Pituitary gland PKC activity was high at birth and decreased with age, contrasting with an increase in PKC-immunolabeled cells.
- Specific PKC subspecies exhibited distinct developmental trajectories; brain PKC tau and delta increased, while PKC zeta decreased, and pituitary PKC delta showed a marked decrease in its major band.
Conclusions:
- Neonatal brain development is characterized by a rapid surge in PKC activity, particularly in the particulate fraction.
- Pituitary PKC expression displays a complex inverse relationship between enzymatic activity and cellular labeling during development.
- Differential regulation of PKC subspecies in the brain and pituitary highlights tissue-specific roles during rat ontogeny.
Abstract:
We have examined the neonatal developmental expression of protein kinase C subspecies (PKCs) in rat brain, pituitary glands and cells by enzymatic activity assays, immunohistochemistry and Western blot analysis with type-specific antibodies. A very large increase (455%) was noticed in brain PKC activity during the first week of life with the particulate fraction (22% of total enzyme activity on day 1) increasing dramatically (900%) during the first week to 50% of enzyme activity. In contrast, the pituitary gland showed high activity on day 1 that decreased progressively to reach the lowest levels at 1 year of age. Paradoxically, the number of pituitary cells immunolabeled for PKC increases as a function of age. Western blot analysis showed only small changes in PKC alpha, PKC beta and PKC epsilon when brains from 6-day-old and 3-month-old female rats were compared, whereas PKC tau and PKC delta increased markedly during this period. On the other hand, brain PKC zeta decreased between 6 days and 3 months of age. Western blot analysis showed no major changes in pituitary PKC alpha, PKC beta and PKC zeta when 6-day-old and 3-month-old female rats were compared, while PKC tau was not detected. The major band of pituitary PKC delta (76 kDa) decreased markedly between 6 days and 3 months of age whereas the minor band (68 kDa) did not change.(ABSTRACT TRUNCATED AT 250 WORDS)