NCBI Summary:
This gene produces a precursor transcript from which a long non-coding RNA is derived by RNase P cleavage of a tRNA-like small ncRNA (known as mascRNA) from its 3' end. The resultant mature transcript lacks a canonical poly(A) tail but is instead stabilized by a 3' triple helical structure. This transcript is retained in the nucleus where it is thought to form molecular scaffolds for ribonucleoprotein complexes. It may act as a transcriptional regulator for numerous genes, including some genes involved in cancer metastasis and cell migration, and it is involved in cell cycle regulation. Its upregulation in multiple cancerous tissues has been associated with the proliferation and metastasis of tumor cells. [provided by RefSeq, Mar 2015]
General function
RNA metabolism, RNA binding
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Cellular localization
Cytoplasmic
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MALAT1 is involved in the pathophysiological process of PCOS by modulating TGFβ signaling in granulosa cells. Zhang D et al. (2019) Polycystic ovary syndrome (PCOS) is an endocrine disorder, the etiology of which is complex and unclear. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a conserved long non-coding RNA which has been found to play a role in the pathophysiological process of reproductive system diseases, such as endometriosis and pregnancy loss. However, the role of MALAT1 in PCOS is still unknown. In this study, reduced MALAT1 expression was found in granulosa cells (GCs) from 68 patients with PCOS and 30 healthy controls, which relates to upregulated cell proliferation and downregulated apoptosis. Using phosphorylation pathway profiling array, MALAT1 reduction was identified to contribute to the repression of transforming growth factor beta (TGFβ) signaling in GCs. Subsequently, MALAT1 was confirmed to function as a competing endogenous RNA (ceRNA), interacting with miR-125b and miR-203a. Meanwhile, miR-125b and miR-203a was identified as two novel TGFβ signaling negative regulators by targeting TGFBR1 and TGFBR2. Finally, MALAT1 knockdown was found to induce the upregulation of miR-125b and miR-203a, which further repressed TGFβ signaling, changed some downstream gene expression, and resulted in a disordered cell cycle. In conclusion, MALAT1 reduction was identified in GCs, which may contribute to the pathophysiological processes of PCOS by regulating TGFβ signaling through sponging miR-125b and miR-203a.//////////////////
Ovarian function
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Expression regulated by
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Ovarian localization
Granulosa
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Down-regulation of long non-coding RNA MALAT1 inhibits granulosa cell proliferation in endometriosis by up-regulating P21 via activation of the ERK/MAPK pathway. Li Y et al. (2018) Is there a specific mechanism underlying the association between lung adenocarcinoma transcript 1 (MALAT1) and endometriosis-related infertility? The down-regulation of MALAT1 in endometriosis granulosa cells (GCs) may have an adverse effect on the growth and development of oocytes by inhibiting GC proliferation, due to cell cycle-dependent mechanisms that enhance P21 expression through activation of the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) pathway. The association between endometriosis and infertility is well supported throughout the literature, and endometriosis per se and its surgical treatment have an adverse effect on the ovarian reserve and on oocyte development. MALAT1, one of the most extensively expressed and evolutionarily conserved transcripts, has been implicated to play a role in human development and many diseases. However, little is known about the role of MALAT1 long non-coding RNA (lncRNA) in endometriosis and its associated infertility. We measured MALAT1 lncRNA expression levels in GCs from 52 endometriosis patients and 52 controls. Also, MALAT1 was knocked down in a human GC tumor-derived cell line, KGN, to investigate the role of MALAT1 and its molecular mechanism in cell proliferation. GCs were collected from women with or without endometriosis undergoing IVF or ICSI treatment. All endometriosis patients were diagnosed by laparoscopy or laparotomy, and control patients were limited to male factor or tubal disease and had a normal ovarian reserve. Quantitative real-time PCR (qRT-PCR) was used to measure the differential expression levels of MALAT1 lncRNA between endometriosis patients and controls. The receiver operating characteristic (ROC) curve was drawn to evaluate the diagnostic values of MALAT1 in endometriosis. In the KGN cell line, MALAT1 was knocked down with locked nucleic acid GapmeRs. Cell counting kit-8 assays, ethynyl-2-deoxyuridine assays and flow cytometry were used to study the role of MALAT1 in cell proliferation and cell-cycle progression, and western blotting was performed to detect the potential underlying mechanism. We first found that MALAT1 lncRNA was significantly down-regulated in endometriosis GCs and was associated with the antral follicle count (R = 0.376, P < 0.001 versus control). In addition, MALAT1 lncRNA levels were significantly lower in the GCs of infertile women with advanced stages of endometriosis (P = 0.01 versus control). The ROC curves illustrated strong separation between all the endometriosis patients and the control group (AUC: 0.705; 95% CI: 0.606-0.804; P < 0.001), Stage I-II and control group (AUC: 0.651; 95% CI: 0.536-0.767; P = 0.016), and Stage III-IV and control group (AUC: 0.827; 95% CI: 0.718-0.936; P < 0.001). MALAT1 lncRNA was primarily localized in the nuclei of GCs. We found a negative correlation between MALAT1 lncRNA and P21 mRNA in the GCs from patients (R = -0.628; P < 0.001). MALAT1 knockdown in KGN cells inhibited cell proliferation and cell-cycle progression. In addition, MALAT1 knockdown induced an increase in both the mRNA and protein levels of P21, and of P53, phosphorylated ERK1/2 (p-ERK1/2) and phosphorylated c-Jun N-terminal protein kinase (p-JNK) protein levels, as well as causing a decrease in cyclin dependent kinase 2 (CDK2), cyclin D1 and p-P38 MAPK protein levels. Furthermore, inhibition of the ERK/MAPK pathway with U0126, the up-regulation of p-ERK1/2, P21 and P53, and the down-regulation of CDK2 and cyclin D1 by the knockdown of MALAT1 were all attenuated by MALAT1 knockdown. Therefore, MALAT1 may regulate GC proliferation through P21/P53-dependent control of the cell cycle, and the ERK/MAPK pathway participates in this process. None. The hormonal treatment used in IVF and surgical removal of endometriotic lesions may have altered MALAT1 expression in GCs. The ovarian granulosa-like tumor cell line, KGN, was used for further functional and mechanistic studies due to the difficulties in obtaining human GCs in sizable amounts and maintaining primary cultures. Our finding represents the first example of an lncRNA-based mechanism in endometriosis GCs. Women with endometriosis show altered MALAT1 expression levels in GCs that may impair fertility by regulating the function of GCs. Therefore, analysis of MALAT1 and its molecular mechanisms of action provide new insights into the pathogenesis of endometriosis and its associated infertility. This work was supported by the National Natural Science Foundation of China (grant number: 81671524) and the National key research and development program of China (grant numbers: 2017YFC1001100, 2017YFC1001103). The authors declare there is no conflict of interest.//////////////////
Follicle stages
Primordial, Primary, Secondary
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Transcriptome Analysis of Long Non-coding RNAs and Genes Encoding Paraspeckle Proteins During Human Ovarian Follicle Development. Ernst EH et al. (2018) Emerging evidence indicated that many long non-coding (lnc)RNAs function in multiple biological processes and dysregulation of their expression can cause diseases. Most regulatory lncRNAs interact with biological macromolecules such as DNA, RNA, and protein. LncRNAs regulate gene expression through epigenetic modification, transcription, and posttranscription, through DNA methylation, histone modification, and chromatin remodeling. Interestingly, differential lncRNA expression profiles in human oocytes and cumulus cells was recently assessed, however, lncRNAs in human follicle development has not previously been described. In this study, transcriptome dynamics in human primordial, primary and small antral follicles were interrogated and revealed information of lncRNA genes. It is known that some lncRNAs form a complex with paraspeckle proteins and therefore, we extended our transcriptional analysis to include genes encoding paraspeckle proteins. Primordial, primary follicles and small antral follicles was isolated using laser capture micro-dissection from ovarian tissue donated by three women having ovarian tissue cryopreserved before chemotherapy. After RN sequencing, a bioinformatic class comparison was performed and primordial, primary and small antral follicles were found to express several lncRNA and genes encoding paraspeckle proteins. Of particular interest, we detected the lncRNAs XIST, NEAT1, NEAT2 (MALAT1), and GAS5. Moreover, we noted a high expression of FUS, TAF15, and EWS components of the paraspeckles, proteins that belong to the FET (previously TET) family of RNA-binding proteins and are implicated in central cellular processes such as regulation of gene expression, maintenance of genomic integrity, and mRNA/microRNA processing. We also interrogated the intra-ovarian localization of the FUS, TAF15, and EWS proteins using immunofluorescence. The presence and the dynamics of genes that encode lncRNA and paraspeckle proteins may suggest that these may mediate functions in the cyclic recruitment and differentiation of human follicles and could participate in biological processes known to be associated with lncRNAs and paraspeckle proteins, such as gene expression control, scaffold formation and epigenetic control through human follicle development. This comprehensive transcriptome analysis of lncRNAs and genes encoding paraspeckle proteins expressed in human follicles could potentially provide biomarkers of oocyte quality for the development of non-invasive tests to identify embryos with high developmental potential.//////////////////