NCBI Summary:
This gene encodes a membrane protein that is a member of a class of protein-tyrosine kinases (PTK) characterized by the presence of a second phosphotransferase-related domain immediately N-terminal to the PTK domain. The encoded kinase phosphorylates STAT proteins (signal transducers and activators of transcription) and plays a key role in interferon-alpha/beta and interferon-gamma signal transduction. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Mar 2016]
General function
Enzyme, Transferase
Comment
Cellular localization
Cytoskeleton
Comment
Ovarian function
Initiation of primordial follicle growth, Luteinization, Oogenesis, Oocyte maturation
Comment
Janus Kinase JAK1 maintains the ovarian reserve of primordial follicles in the mouse ovary. Sutherland JM et al. (2018) Is the Janus kinase and signal transducer and activator of transcription (JAK-STAT) signalling pathway involved in ovarian follicle development and primordial follicle activation? JAK1 is a key factor involved in the regulation of primordial follicle activation and maintenance of the ovarian reserve. A series of integrated, intrinsic signalling pathways (including PI3K/AKT, mTOR and KITL) are responsible for regulating the ovarian reserve of non-growing primordial follicles and ultimately female fertility. The JAK-STAT signal transduction pathway is highly conserved with established roles in cell division and differentiation. Key pathway members (specifically JAK1, STAT3 and SOCS4) have been previously implicated in early follicle development. A laboratory animal study was undertaken using the C57Bl/6 inbred mouse strain as a model for human ovarian follicle development. To determine which Jak genes were most abundantly expressed during primordial follicle activation, mRNA expression was analysed across a developmental time-course, with ovaries collected from female mice at post-natal days one (PND1), four (PND4), eight (PND8), as well as at six weeks (6WK) and seven months (7MTH) (n ≥ 4). Functional analysis of JAK1 was performed on PND2 mouse ovaries subjected to in vitro explant culture treated with 12.5μM Ruxolitinib (JAK inhibitor) or vehicle control (DMSO) for 48 hours prior to histological assessment (n ≥ 4). The expression and localisation of the JAK family during ovarian follicle development in the C57Bl/6 inbred mouse strain were evaluated using quantitative PCR, immunoblotting and immunolocalisation. Functional studies were undertaken using the JAK inhibitor Ruxolitinib to investigate the underpinning cellular mechanisms via biochemical in vitro inhibition and histological assessment of intact neonate ovaries. All experiments were replicated at least 3 times using tissue from different mice unless otherwise stated. Jak1 is the predominant Jak mRNA expressed in the C57Bl/6 mouse ovary across all developmental time points assessed (p ≤ 0.05). Forty-eight hour inhibition of JAK1 with Ruxolitinib of PND2 ovaries in vitro demonstrated concomitant acceleration of primordial follicle activation and apoptosis (p ≤ 0. 001) and upregulation of downstream JAK-STAT pathway members STAT3 and suppressors of cytokine signaling 4 (SOCS4). N/A. Results are shown in one species, the C57Bl/6 mouse strain as an established model of human ovary development. Ruxolitinib also inhibits JAK2, with decreased efficacy. However, Jak2 mRNA had limited expression in the mouse ovary, particularly at the neonatal stages of follicle development, thus any effect of Ruxolitinib on primordial follicle activation was unlikely to be mediated via this isoform. This study supports a key role for JAK1 in the maintenance and activation of primordial follicles, with potential for targeting the JAK-STAT pathway as a method of regulating the ovarian reserve and female fertility. This project has been funded by the Australian National Health and Medical Research Council (G1600095) and The Hunter Medical Research Institute Bob and Terry Kennedy Children's Research Project Grant in Pregnancy & Reproduction (G1501433). All authors declare no conflict of interests.//////////////////
Expression regulated by
LH
Comment
Gene expression increased. Luteinization of porcine preovulatory follicles leads to systematic changes in follicular gene expression. Agca C et al. The LH surge initiates the luteinization of preovulatory follicles and causes hormonal and structural changes that ultimately lead to ovulation and the formation of corpora lutea. The objective of the study was to examine gene expression in ovarian follicles (n = 11) collected from pigs (Sus scrofa domestica) approaching estrus (estrogenic preovulatory follicle; n = 6 follicles from two sows) and in ovarian follicles collected from pigs on the second day of estrus (preovulatory follicles that were luteinized but had not ovulated; n = 5 follicles from two sows). The follicular status within each follicle was confirmed by follicular fluid analyses of estradiol and progesterone ratios. Microarrays were made from expressed sequence tags that were isolated from cDNA libraries of porcine ovary. Gene expression was measured by hybridization of fluorescently labeled cDNA (preovulatory estrogenic or -luteinized) to the microarray. Microarray analyses detected 107 and 43 genes whose expression was decreased or increased (respectively) during the transition from preovulatory estrogenic to -luteinized (P<0.01). Cells within preovulatory estrogenic follicles had a gene-expression profile of proliferative and metabolically active cells that were responding to oxidative stress. Cells within preovulatory luteinized follicles had a gene-expression profile of nonproliferative and migratory cells with angiogenic properties. Approximately, 40% of the discovered genes had unknown function.