Asymmetrical allocation ofJAK1mRNAduring spermatogonial stem cell division inXenopus laevis

Abstract

During Xenopus spermatogenesis, each primary spermatogonium (PG), the largest single cell in the testis, undergoes mitotic divisions with a concomitant decrease in size to produce smaller differentiating spermatogonia. The spermatogonial stem cells (SSCs) occur in this PG population. Taking advantage of identifiable and isolatable properties of Xenopus SSCs, we examined JAK1 gene expression during the spermatogenesis because there have been reports on the important role of JAK/STAT pathway in regulating the status of SSCs in Drosophila and mouse. Surprisingly, in situ hybridization revealed the presence of JAK1 mRNA in the differentiating spermatogonia and primary spermatocytes as well as some PGs. Inhibition of JAK1 activity in the testis caused a decrease in percentage of BrdU-incorporating spermatogonia, suggesting that JAK1 was at least involved in regulation of spermatogonial proliferation. Interestingly, single cell reverse transcription-polymerase chain reaction (RT-PCR) clearly showed two different types of SSCs: SSCs with JAK1 mRNA (JAK1 + ) or without JAK1 mRNA (JAK1 À ). Since JAK1 À SSC level was increased by induction of testis regeneration, self-renewing SSCs were thought to be JAK1À . In addition, we found barrel-shaped PGs, in which JAK1 mRNA was localized asymmetrically to one half of the cell. The stainability with propidium iodide and morphology of two nuclei in the barrelshaped PG were similar to those of PG nucleus. Based on the above observations, we propose the hypothesis that JAK1 + SSC is preparing for production of PGs destined to differentiate (destined PGs) and the accumulated JAK1 mRNA in the SSC is distributed exclusively into the destined PGs through mitotic division.

The Regulatory Effects of JAK2/STAT3 on Spermatogenesis and the Redox Keap1/Nrf2 Axis in an Animal Model of Testicular Ischemia Reperfusion Injury

“…Thus, JAK2 activation during testicular oxidative stress and triggering apoptosis is considered a protective mechanism to preserve overall testicular function. This further confirms that JAK2 expression is modulated in parallel to the changes in the testis microenvironment in support of maintaining balanced testis homeostasis during adverse pathological conditions such as tIRI [29].…”

“…During the early developmental stages of the testis, the JAK/STAT pathway is the mediator of key signals produced by the somatic gonad cells that regulate the development of male germ cells [ 28 ]. It was reported that the JAK2 gene expression is respectively altered to correspond to the status of the testis, which links its activity to the homeostasis of the testis [ 29 ]. Furthermore, the survival of germ cells in the presence of reproductive toxins was attributed to the activation of the JAK/STAT pathway [ 30 ].…”

A Study of Differential Expression of Testicular Genes in Various Reproductive Phases of Hemidactylus flaviviridis (Wall Lizard) to Derive Their Association with Onset of Spermatogenesis and Its Relevance to Mammals

“…As the active testis of wall lizards and adult testis of mice are highly proliferative, a higher expression of Arih1 in those phases of testis in wall lizards and mice can be justified. In the predicted interactome database, this protein interacts with the JAK1, which is a protein-tyrosine kinase found in human spermatozoa [ 32 ] and helps in germ cell differentiation in Xenopus [ 33 ]. RASSF7 is a ras association domain-containing protein 7, which negatively regulates stress-induced JNK activation [ 34 ].…”