Genini et al. (1997) used subtractive cloning to isolate a gene that is downregulated during transformation of normal
myoblasts to rhabdomyosarcoma cells. The gene, termed DRAL for 'down-regulated in rhabdomyosarcoma LIM protein,'
encodes a 279-amino acid polypeptide with an observed mass of 32 kD. The protein sequence contains 4 complete LIM
domains and the second half of a fifth LIM domain. DRAL appears to be a member of the LIM-only class of proteins, which
consist primarily of LIM domains and little else. Southern blotting revealed a single-copy gene that is conserved among
vertebrates.
Northern blotting revealed that the DRAL gene is expressed at highest levels in heart and ovary, and at lower
levels in skeletal muscle, prostate, testis, small intestine, and colon. Results of Northern blotting of tumor cell lines suggested
that this gene may be downregulated during transformation of a variety of cell types.
NCBI Summary:
This gene encodes a member of the four-and-a-half-LIM-only protein family. Family members contain two highly conserved, tandemly arranged, zinc finger domains with four highly conserved cysteines binding a zinc atom in each zinc finger. This protein is thought to have a role in the assembly of extracellular membranes. Also, this gene is down-regulated during transformation of normal myoblasts to rhabdomyosarcoma cells and the encoded protein may function as a link between presenilin-2 and an intracellular signaling pathway. Multiple alternatively spliced variants encoding different isoforms have been identified. [provided by RefSeq, Jan 2016]
General function
Nucleic acid binding, DNA binding, Transcription factor
Comment
Cellular localization
Nuclear
Comment
Ovarian function
Follicle atresia
Comment
Expression, location, and biological effects of four and a half LIM domain protein (FHL2) on granulosa cells in ovine. Zhang L et al. (2020) Previous studies have shown that four and a half LIM domain protein (FHL2) plays an essential role in the regulation of follicular development in mammals. Although the FHL2 genes of human and mouse have been well characterized, the expression and location of FHL2 in ovary and the biological functions of FHL2 on granulosa cells (GCs) of ovine are still not clear. In this study, full-length complementary DNA (cDNA) of FHL2 from ovine follicular GCs was amplified by real-time PCR (RT-PCR). The expression and location of FHL2 in ovary and GCs of ovine were studied by immunohistochemistry and immunofluorescence, and the biological effects of FHL2 on the cell proliferation, cell apoptosis, cell cycles, and expression level of related genes of ovine GCs were also explored by overexpression or knockdown of FHL2. The results indicated that FHL2 was expressed in ovine follicular GCs and the sequence of the FHL2 cDNA was consistent with that predicted in GenBank, which did not cause an amino acid change. According to the results, FHL2 was expressed in ovine ovary and mainly located in the cytoplasm and nucleus of GCs. In addition, overexpression of FHL2 significantly reduced the cell viability, promoted the cell apoptosis and decreased the percentage of G0/G1 and S phase cells. RT-PCR showed that overexpression of FHL2 significantly increased the mRNA expression level of Bax and decreased the expression of Bcl-2 and the Bcl-2/Bax mRNA ratio compared to the control group. Besides, the knockdown of FHL2 gene in ovine GCs significantly improved the cell viability, suppressed the cell apoptosis, decreased the mRNA expression level of Caspase3 gene and increased the Bcl-2/Bax mRNA ratio, and increased the percentage of S and G2/M phase cells. Our results suggest that FHL2 may play an important role in the biological functions of GCs in ovine.//////////////////Up-regulated FHL2 inhibits ovulation through interacting with androgen receptor and ERK1/2 in polycystic ovary syndrome. Zhou R et al. (2020) The ovulatory dysfunction mechanisms underlying polycystic ovary syndrome (PCOS) are not completely understood. There is no effective therapy for PCOS so far. We measured the expression of four and a half LIM domain 2 (FHL2) and other related-genes in human granulosa cells (hGCs) from patients with and without PCOS. To minimise the heterogeneity of patients with PCOS, we only included PCOS patients meeting all three criteria according to the revised Rotterdam consensus. The in vitro effects of FHL2 on ovulatory genes and the underlying mechanisms were examined in KGN cells. The role of FHL2 in ovulation was investigated in vivo by overexpressing FHL2 in rat ovaries via intrabursal lentivirus injection. Increased FHL2 and androgen receptor (AR) expression and decreased CCAAT/enhancer-binding protein β (C/EBPβ) expression were observed in hGCs from patients with PCOS. FHL2 inhibited the expression of ovulation-related genes, including phosphorylated ERK1/2, C/EBPβ, COX2 and HAS2 in KGN cells. It was partially by interacting with AR to act as its co-regulator to inhibit C/EBPβ expression and by binding to ERK1/2 to inhibit its phosphorylation. Moreover, FHL2 abundance in hGCs was positively correlated with the basal serum testosterone concentration of patients with PCOS, and dihydrotestosterone (DHT)-induced FHL2 upregulation was mediated by AR signalling in KGN cells. Additionally, lentiviral-mediated functional FHL2 overexpression in rat ovaries for 1 week contributed to an impaired superovulatory response, displaying decreased numbers of retrieved oocytes and a lower MII oocyte rate. 3-week FHL2 overexpression rat models without superovulation led to acyclicity and polycystic ovary morphology. Our findings provide novel insights into the mechanisms underlying the pathogenesis of PCOS, suggesting that FHL2 could be a potential treatment target for ovulatory obstacles in PCOS. FUND: National Key Research and Development Program of China, National Natural Science Foundation, National Institutes of Health project and Shanghai Commission of Science and Technology.//////////////////
Expression regulated by
Comment
Ovarian localization
Granulosa
Comment
The LIM Domain Protein FHL2 Interacts with the NR5A Family of Nuclear Receptors and CREB to Activate the Inhibin-a Subunit Gene in Ovarian Granulosa Cells. Matulis CK et al. Nuclear receptor transcriptional activity is enhanced by interaction with coactivators. The highly related nuclear receptor 5A (NR5A) subfamily members liver receptor homolog 1 and steroidogenic factor 1 bind to and activate several of the same genes, many of which are important for reproductive function. To better understand transcriptional activation by these nuclear receptors, we sought to identify interacting proteins that might function as coactivators. The LIM domain protein four and a half LIM domain 2 (FHL2) was identified as interacting with the NR5A receptors in a yeast two-hybrid screen of a human ovary cDNA library. FHL2, and the closely related FHL1, are both expressed in the rodent ovary and in granulosa cells. Small interfering RNA-mediated knockdown of FHL1 and FHL2 in primary mouse granulosa cells reduced expression of the NR5A target genes encoding inhibin-a and P450scc. In vitro assays confirmed the interaction between the FHL and NR5A proteins and revealed that a single LIM domain of FHL2 is sufficient for this interaction, whereas determinants in both the ligand binding domain and DNA binding domain of NR5A proteins are important. FHL2 enhances the ability of both liver receptor homolog 1 and steroidogenic factor 1 to activate the inhibin-a subunit gene promoter in granulosa cells and thus functions as a transcriptional coactivator. FHL2 also interacts with cAMP response element-binding protein and substantially augments activation of inhibin gene expression by the combination of NR5A receptors and forskolin, suggesting that FHL2 may facilitate integration of these two signals. Collectively these results identify FHL2 as a novel coactivator of NR5A nuclear receptors in ovarian granulosa cells and suggest its involvement in regulating target genes important for mammalian reproduction.