Literature Review - Telomerase Activity
Spermatogenesis is the biological process through which spermatozoa are produced in the male reproductive system. The process begins with spermatogonia, which are undifferentiated male germ cells produced in the seminiferous tubules, and divide via mitosis to yield two primary spermatocytes. Spermatocytes then undergo the first stage of meiosis to produce two secondary spermatocytes, which divide into two spermatids by meiosis II. The spermatids then develop into spermatozoa via a process called spermiogenesis. Spermatogenesis is a continuous process that lasts throughout the life of a male human being as there is a constant supply of spermatogonia. There are two basic types of spermatogonia located in the basement membrane of the seminiferous epithelium, characterized as either a (pale) or A (dark) based on the morphology of the nucleus. A (dark) spermatogonia act as a reserve stem cell population which rarely undergo cell division, whereas A (pale) spermatogonia are actively dividing stem cells responsible for the maintenance of spermatogenesis (Izadyar et al., 2011).
The ability of spermatogonia to replicate continuously can be attributed to the presence of the enzyme telomerase. Telomerase is an important enzyme in the process of cell division as it regulates the length of telomeres (regions of repeated nucleotide sequences at the ends of chromatids that prevent chromosomes from deteriorating or fusing with adjacent chromosomes). Normal DNA replication causes the shortening of telomeres, leading to deterioration and eventually death of the cell. However, telomerase counters this shortening by ensuring that the length of the telomeres is restored, thus prolonging its functionality and lifespan. Common cells that possess enzyme telomerase include stem cells, male and female germline cells, early embryos, granulosa cells, and most cancer cells (Ozturk, 2015).
Since spermatogonia replicate continuously similar to cancer cells, there is the possibility that they are likely to become cancer cells owing to the presence of telomerase in both cells. The main purpose of this paper is to evaluate and compare current literature on the role of telomerase in the process of spermatogenesis and the replication of cancer cells. The paper will also show why spermatogonia cannot easily divide into cancer cells although both contain high levels of the enzyme telomerase.Telomerase Activity in SpermatogenesisTelomeres are important components of chromosomes in eukaryotic cells. Together with the telomere-associated proteins, they contribute to the genomic integrity of the cells in addition to participating in the other functions such as motion, localization and attachment of the chromosomes to the nuclear membrane. In addition, telomeres facilitate the pairing of homologous chromosomes, formation of synapses, and homologous recombination during the process of cell division (Ozturk, 2015). Normally, the length of telomeres in a replicating cell shortens with increasing DNA replications as the replication process is not capable of replenishing the lost portions of the telomere. Other causes for the shortening of telomeres include genetic predisposition, psychological stress, lifestyle factors, genotoxic insults and chronic exposure to reactive oxygen species. Telomerase is important in the process of spermatogenesis as it counters the shortening …
