Dissertation
Prostasomes: membrane vesicles with vital skills!
Mammalian cells produce membrane vesicles that play a vital role as messengers in the communication between production cells and target cells. In her doctoral dissertation, Doctoral Candidate Marian Aalberts describes the differences, composition and function of prostasomes, which are membrane vesicles secreted by prostate cells into seminal fluid. In men with prostate cancer, the prostasomes may also enter the bloodstream. Prostasomes stimulate the motility of sperm cells and influence their capacitation – the process that gives sperm cells their ability to fertilise egg cells. Prostasomes also increase the sperm cells’ chances of survival in the fallopian tubes by influencing the female immune system. However, scientists currently know little about how the prostasomes perform these various functions.
Aalberts has isolated two types of prostasomes from human seminal fluid: a larger type (100nm) and a smaller type (50nm), which differed in their composition. Researchers have long known that membrane vesicles secreted by other types of cells can contain RNA as well as proteins and fats, and that the RNA in the vesicles can influence protein production in target cells. Aalberts has proven that the 100nm prostasomes contain a previously unknown type of RNA molecule. Although their physiological functions are as yet unknown, the presence of these RNA molecules in the blood may be an indication of prostate cancer.
In horses, the 50nm prostasomes appeared to attach themselves selectively to capacitated sperm cells, but not to uncapacitated sperm cells. The prostasomes delayed the completion of the capacitation process, perhaps in order to allow the sperm cells to find an egg cell before capacitation.
| Date and time: |
4/9/2012 12:45 |
| Location: |
University Hall, Domplein 29, Utrecht |
| |
| PhD student: |
Marian Aalberts |
| Faculty: |
Faculty of Veterinary Medicine |
| Thesis: |
Characterization of two types of prostasomes with distinct molecular compositions |
| Supervisor 1: |
Prof. W. Stoorvogel, PhD |
| Supervisor 2: |
Prof. T.A.E. Stout, PhD, DVM |