Alternative titles; symbols
HGNC Approved Gene Symbol: INSL3
SNOMEDCT: 204878001; ICD10CM: Q53.9; ICD9CM: 752.51;
Cytogenetic location: 19p13.11 Genomic coordinates (GRCh38): 19:17,816,512-17,821,519 (from NCBI)
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
|---|---|---|---|---|
| 19p13.11 | Cryptorchidism | 219050 | Autosomal dominant | 3 |
Leydig insulin-like protein belongs to the insulin-like hormone superfamily (Adham et al., 1993), which comprises insulin (176730), relaxin (179730), and insulin-like growth factors I (IGF1; 147440) and II (IGF2; 147470). The members of this family are characterized by a signal peptide, a B-chain, a connecting C-peptide, and an A-chain. Burkhardt et al. (1994) reported the isolation and sequencing of the human Leydig insulin-like protein. The deduced amino acid sequence of the pro-Leydig insulin-like protein has a primary structure more similar to that of proinsulin than to pro-IGF1 and pro-IGF2. The protein, designated INSL3, is expressed exclusively in prenatal and postnatal Leydig cells.
To determine the functional region of the mouse Insl3 promoter and factors controlling Insl3 gene expression, Zimmermann et al. (1998) used 2.1 kb of the 5-prime-flanking region of the mouse Insl3 gene to generate chimeric constructs with the chloramphenicol acetyltransferase (CAT) gene. Transient transfections of MA10 Leydig cells, LTK- fibroblasts, and F9 embryonic cells by a series of 5-prime-deleted mouse Insl3 promoter-CAT constructs revealed that the sequence between nucleotides -157 and +4 directed the transcription of the reporter gene in MA10 but not in LTK- and F9 cells, indicating that the determinants of Leydig cell-specific expression reside within this region. DNase I footprint analysis revealed that the sequences designated SF-1/1, SF-1/2, and SF-1/3 within 3 DNase I-protected regions are homologous to the consensus binding site of steroidogenic factor-1 (SF1; 184757). The authors concluded that SF1 plays an essential role in transcriptional activation of the Insl3 promoter.
Kumagai et al. (2002) noted that, like male mice lacking Insl3, male mice lacking the Lgr8 gene (606655) show cryptorchidism. Using HEK293 cells transfected with human LGR8, they demonstrated increased cAMP production following treatment with human, rat, or ovine INSL3. Crosslinking experiments confirmed direct interaction between INSL3 and LGR8. Cultured rat gubernacular cells expressed endogenous Lgr8, and treatment with Insl3 led to a dose-dependent increase in cAMP production and increased cell proliferation. Kumagai et al. (2002) concluded that LGR8 is a cellular receptor for INSL3.
Wikstrom et al. (2006) studied changes in INSL3 levels during spontaneous puberty in healthy boys, boys with aromatase inhibitor-induced hypergonadotropic hyperandrogenism, and boys with Leydig cell dysfunction (Klinefelter syndrome). Onset of puberty was associated with a significant increase in INSL3 levels. Adult INSL3 levels (greater than 0.55 ng/ml) were attained at bone ages of 13 to 14 years. Boys with letrozole-induced hypergonadotropic hyperandrogenism had, after 12 months of therapy, higher INSL3 levels than did placebo-treated boys. In Klinefelter syndrome boys during spontaneous puberty, after an initial increase similar to that in healthy boys, INSL concentrations leveled off despite hyperstimulation by luteinizing hormone (LH; see 152780). Positive correlations occurred between serum INSL3 and LH and between INSL3 and testosterone levels in all 3 groups (P less than 0.0001). The authors concluded that serum INSL3 concentrations may serve as novel markers for onset and normal progression of puberty.
Burkhardt et al. (1994) reported that the INSL3 gene comprises 2 exons and 1 intron, and that the organization of the gene is similar to that of insulin and relaxin. The transcription start site is localized 14 bp upstream of the translation start site. The human genome contains a single copy of the INSL3 gene.
By isotopic in situ hybridization, Burkhardt et al. (1994) mapped the INSL3 gene to 19p13.2-p12.
Tomboc et al. (2000) used SSCP analysis to screen the coding regions of the 2-exon INSL3 gene in genomic DNA samples obtained from 145 formerly cryptorchid patients and 36 adult male controls. Two mutations and several polymorphisms were identified. Both mutations were located in the connecting peptide region of the protein. The authors concluded that the frequency of INSL3 gene mutations as a cause of cryptorchidism is low, because only 2 of 145 (1.4%) formerly cryptorchid patients were found to have mutations: arg63 to ter (R63X; 146738.0005), which was likely to be pathogenetic because it was found in a boy with undescended right testis and history of incarcerated right inguinal hernia, and pro93 to leu (P93L; 146738.0002), which was found in an 8-month-old baby with nonpalpable intraabdominal right testis.
Canto et al. (2003) studied genomic DNA from 150 patients with idiopathic cryptorchidism. A heterozygous asn86-to-lys mutation (N86K; 146738.0001) in the INSL3 gene was found in 1 patient whose mother was a heterozygous carrier of the mutation and whose father was homozygous wildtype.
Ferlin et al. (2003) sequenced the INSL3 and LGR8 genes in a cohort of 87 patients with corrected cryptorchidism and 80 controls and found 3 mutations in the INSL3 gene in 4 patients (e.g., 146738.0002) and 1 LGR8 mutation (see 606655.0001) in 4 patients (8 of 87, 9.2%). The authors concluded that INSL3-LGR8 mutations are frequently associated with human cryptorchidism and are maternally inherited.
Nef and Parada (1999) showed that mice mutant for Insl3, which is expressed in the developing testis, are viable, but exhibit bilateral cryptorchidism due to developmental abnormalities of the gubernaculum, resulting in abnormal spermatogenesis and infertility. Female homozygotes have impaired fertility associated with deregulation of the estrous cycle. The findings revealed roles for INSL3 in the development of the urogenital tract and in female fertility. INSL3 may act as a hormone to regulate the growth and differentiation of the gubernaculum, thereby mediating intraabdominal testicular descent.
Zimmermann et al. (1999) also reported that mice deficient in Insl3 displayed bilateral cryptorchidism and gubernaculum feminization during embryogenesis. The findings of Nef and Parada (1999) differed from those of Zimmermann et al. (1999) in 2 respects: first, Nef and Parada (1999) found that heterozygous mice had partial cryptorchidism, suggesting dosage sensitivity of Insl3 for testicular descent. In contrast, Zimmermann et al. (1999) did not observe delays in testicular descent in heterozygous males. The heterozygous phenotype appeared to resemble most cases of human cryptorchidism, where partial testicular descent at birth often self-corrects. In the second place, Zimmermann et al. (1999) found no effects on the estrous cycle.
Adham et al. (2002) investigated whether in vivo the Insl3-mediated gubernaculum development is independent of androgens. They generated transgenic male and female mice that overexpressed Insl3 in the pancreas during fetal and postnatal life. Expression of the transgenic allele in the Insl3-deficient mice rescued the cryptorchidism in male mutants, indicating that the islet beta-cells efficiently processed the Insl3 gene product to the functional hormone. All transgenic females displayed bilateral inguinal hernia. The processus vaginalis developed containing intestinal loops. The mullerian derivatives gave rise to oviduct, uterus, and upper vagina, and wolffian duct derivatives were missing, indicating the absence of the androgen- and anti-mullerian hormone-mediated activities in transgenic females. The ovaries descended into a position over the bladder and attached to the abdominal wall via the well developed cranial suspensory ligament and the gubernaculum. Administration of dihydrotestosterone during prenatal development suppressed formation of the cranial suspensory ligament and thereby allowed the descent of the ovaries into the processus vaginalis. The authors concluded that Insl3-mediated activity induces gubernaculum development and precludes a role of androgen in this process. Furthermore, they noted that the transgenic females exhibited reduced fertility, which is due to fetal mortality during midgestation.
In 1 of 150 patients with idiopathic cryptorchidism (219050), Canto et al. (2003) found a heterozygous 2560C-G transversion in exon 2 of the INSL3 gene, resulting in an asn86-to-lys (N86K) substitution in the A-chain of the protein. The change was considered probably deleterious because it led to a nonconservative amino acid substitution, changing a highly conserved residue.
In a patient with unilateral cryptorchidism (219050), Tomboc et al. (2000) identified a heterozygous 2511C-T transition in the INSL3 gene, resulting in a pro69-to-leu (P69L) substitution.
In a patient with unilateral cryptorchidism, Ferlin et al. (2003) detected the same mutation, which they reported as a heterozygous 278C-T transition in the INSL3 gene that caused a pro93-to-leu (P93L) change within an alpha-helix of the insulin-like-3 protein. The mutation was inherited from the phenotypically normal mother.
In a patient with unilateral cryptorchidism (219050) originally reported by Marin et al. (2001), Ferlin et al. (2003) found a heterozygous 304C-T transition in the INSL3 gene that caused an arg102-to-cys (R102C) amino acid change. The mutation was inherited from the mother, whose history was negative for reproductive dysfunction and any other pathologic condition.
In 2 patients with bilateral cryptorchidism (219050) with bilateral severe testiculopathy, Ferlin et al. (2003) detected a heterozygous 305G-A transition in the INSL3 gene that caused an arg102-to-his (R102H) change in the insulin-like-3 protein.
In a patient with unilateral cryptorchidism (219050), Tomboc et al. (2000) identified a 2450C-T transition in the INSL3 gene, resulting in an arg49-to-ter (R49X) substitution.
Adham, I. M., Burkhardt, E., Benahmed, M., Engel, W. Cloning of a cDNA for a novel insulin-like hormone of the testicular Leydig cells. J. Biol. Chem. 268: 26668-26672, 1993. [PubMed: 8253799]
Adham, I. M., Steding, G., Thamm, T., Bullesbach, E. E., Schwabe, C., Paprotta, I., Engel, W. The overexpression of the Insl3 in female mice causes descent of the ovaries. Molec. Endocr. 16: 244-252, 2002. [PubMed: 11818498] [Full Text: https://doi.org/10.1210/mend.16.2.0772]
Burkhardt, E., Adham, I. M., Brosig, B., Gastmann, A., Mattei, M.-G., Engel, W. Structural organization of the porcine and human genes coding for a Leydig cell-specific insulin-like peptide (LEY I-L) and chromosomal localization of the human gene (INSL3). Genomics 20: 13-19, 1994. [PubMed: 8020942] [Full Text: https://doi.org/10.1006/geno.1994.1121]
Canto, P., Escudero, I., Soderlund, D., Nishimura, E., Carranza-Lira, S., Gutierrez, J., Nava, A., Mendez, J. P. A novel mutation of the insulin-like 3 gene in patients with cryptorchidism. J. Hum. Genet. 48: 86-90, 2003. [PubMed: 12601553] [Full Text: https://doi.org/10.1007/s100380300012]
Ferlin, A., Simonato, M., Bartoloni, L., Rizzo, G., Bettella, A., Dottorini, T., Dallapiccola, B., Foresta, C. The INSL3-LGR8/GREAT ligand-receptor pair in human cryptorchidism. J. Clin. Endocr. Metab. 88: 4273-4279, 2003. [PubMed: 12970298] [Full Text: https://doi.org/10.1210/jc.2003-030359]
Kumagai, J., Hsu, S. Y., Matsumi, H., Roh, J.-S., Fu, P., Wade, J. D., Bathgate, R. A. D., Hsueh, A. J. W. INSL3/leydig insulin-like peptide activates the LGR8 receptor important in testis descent. J. Biol. Chem. 277: 31283-31286, 2002. [PubMed: 12114498] [Full Text: https://doi.org/10.1074/jbc.C200398200]
Marin, P., Ferlin, A., Moro, E., Rossi, A., Bartoloni, L., Rossato, M., Foresta, C. Novel insulin-like 3 (INSL3) gene mutation associated with human cryptorchidism. Am. J. Med. Genet. 103: 348-349, 2001. [PubMed: 11746019]
Nef, S., Parada, L. F. Cryptorchidism in mice mutant for Insl3. Nature Genet. 22: 295-299, 1999. [PubMed: 10391220] [Full Text: https://doi.org/10.1038/10364]
Tomboc, M., Lee, P. E., Mitwally, M. F., Schneck, F. X., Bellinger, M., Witchel, S. F. Insulin-like 3/relaxin-like factor gene mutations are associated with cryptorchidism. J. Clin. Endocr. Metab. 85: 4013-4018, 2000. [PubMed: 11095425] [Full Text: https://doi.org/10.1210/jcem.85.11.6935]
Wikstrom, A. M., Bay, K., Hero, M., Andersson, A.-M., Dunkel, L. Serum insulin-like factor 3 levels during puberty in healthy boys and boys with Klinefelter syndrome. J. Clin. Endocr. Metab. 91: 4705-4708, 2006. [PubMed: 16926256] [Full Text: https://doi.org/10.1210/jc.2006-0669]
Zimmermann, S., Schwarzler, A., Buth, S., Engel, W., Adham, I. M. Transcription of the Leydig insulin-like gene is mediated by steroidogenic factor-1. Molec. Endocr. 12: 706-713, 1998. [PubMed: 9605933] [Full Text: https://doi.org/10.1210/mend.12.5.0107]
Zimmermann, S., Steding, G., Emmen, J. M., Brinkmann, A. O., Nayernia, K., Holstein, A. F., Engel, W., Adham, I. M. Targeted disruption of the Insl3 gene causes bilateral cryptorchidism. Molec. Endocr. 13: 681-691, 1999. [PubMed: 10319319] [Full Text: https://doi.org/10.1210/mend.13.5.0272]