Disease relevance of Insl3

• Mutations of Insl3 or Great cause cryptorchidism (undescended testes) in mice [1].
• In mutant females Insl3 over expression resulted in transabdominal descent of the ovaries to the low abdominal position with the subsequent development of inguinal hernia [2].
• Insl3 is responsible for testicular descent through virilization and outgrowth of the embryonic gubernaculum [3].
• Deletion of the relaxin-like factor (RLF) gene in mice causes retention of testicles and infertility [4].

High impact information on Insl3

• Leydig insulin-like hormone (Insl3) is a member of the insulin hormone superfamily expressed in the developing testis [5].
• Cryptorchidism in mice mutant for Insl3 [5].
• Finally, a constitutively active form of Rlf can stimulate transcriptional activation and cell growth [6].
• Stimulation of gene induction and cell growth by the Ras effector Rlf [6].
• These results suggest that Insl3-mediated activity induces gubernaculum development and precludes a role of androgen in this process [7].

Chemical compound and disease context of Insl3

• Involvement of insulin-like factor 3 (Insl3) in diethylstilbestrol-induced cryptorchidism [8].
• In addition, Insl3 expression causes inguinal hernia in females, suggesting that a combination of estrogen and Insl3 action disrupts proper development of the muscular and connective tissue structures of the abdomen [9].

Biological context of Insl3

• Transgenic overexpression of Insl3, the cognate ligand for Lgr8, does not rescue the mutant phenotype of Lgr7-deficient female mice indicating nonoverlapping functions of the two receptors [10].
• Despite its importance for male sex differentiation and reproductive function in both sexes, very little is known regarding the molecular mechanisms that regulate Insl3 expression [11].
• We show here that mice mutant for Insl3 are viable, but exhibit bilateral cryptorchidism due to developmental abnormalities of the gubernaculum, resulting in abnormal spermatogenesis and infertility [5].
• RESULTS: Of the mice 11 Insl3 homozygote males had significantly impaired testicular descent at embryonic day 16.5 and birth (p <0.01), and the cord was thin and elongated, while 14 heterozygotes and 7 wild-types had normal testicular descent [12].
• MATERIALS AND METHODS: Mice with Insl3 homozygotes (-/-), heterozygotes (+/-) and wild-types (+/+) were examined at embryonic day 16.5 and birth [12].

Anatomical context of Insl3

• Finally, we found that NR4A1 is also implicated in cAMP-induced Insl3 transcription in Leydig cells [11].
• Using RT-PCR, we found that Nr4a1 is coexpressed with Insl3 in purified Leydig cells and in several Leydig cell lines [11].
• The Insl3 gene (originally designated Ley I-L), a member of the insulin-like superfamily, is specifically expressed in Leydig cells of the fetal and postnatal testis and in theca cells of the postnatal ovary [13].
• Microscopically, the gubernaculum of Insl3 homozygotes was small with some muscle development but no central core of mesenchyme at embryonic day 16 [12].
• The insulin-like factor 3 (Insl3), a member of the insulin-like hormone family, is exclusively synthesized in gonads [14].

Associations of Insl3 with chemical compounds

• Male sexual differentiation relies upon testicular secretion of the hormones testosterone, Mullerian inhibiting substance, and insulin-3 (Insl3) [3].
• Tryptophan B27 in the relaxin-like factor (RLF) is crucial for RLF receptor-binding [15].
• Consistent with this observation, alanine substitution of one of these residues (K687) in Rlf significantly reduced affinity for Ras-GTP [16].
• Tissues were fixed in 10% neutral buffered formalin, and utilizing two different antibodies to relaxin-like factor, W3 rabbit anti-bovine and 2-8F mouse anti-bovine, relaxin-like factor was localized in fibroblast-like cells [17].
• Gubernaculum cells in primary culture showed an increased uptake of 5-bromo-2'-deoxyuridine in the presence of RLF compared with controls [4].

Physical interactions of Insl3

• There was substantial atrophy of the urogenital complex and significantly (P < 0.0005) reduced levels of testosterone-dependent testicular relaxin-like factor mRNA expression [18].

Other interactions of Insl3

• Our data indicate that neither Insl3 nor Lgr8 contribute to the RLN signaling pathway [10].
• We tested whether transgenic over expression of Insl3 can reverse inguinoscrotal cryptorchidism in mice deficient in Gnrhr or Hoxa10 genes [2].
• MATERIALS AND METHODS: Hoxa10 and Gnrhr deficient mice were intercrossed with Insl3 transgenic mice [2].
• In double-mutant male mice for Insl3 and androgen receptor genes, testes are positioned adjacent to the kidneys and steadied in the abdomen by the CSL [13].
• Possible factors involved in gubernaculum development are androgens, anti-Müllerian hormone (AMH), and insulin-like factor (Insl3) [19].

Analytical, diagnostic and therapeutic context of Insl3

• Molecular cloning and expression of the relaxin-like factor from the mouse testis [20].
• More extensive Southern blot, polymerase chain reaction and sequencing analyses showed that the published mouse sequence for exon 23 of the JAK3 gene in fact comprises two exons, 23A and 23B, separated by an additional novel intron of 2.2 kb, and that within this intron the promoter and exon 1 of the mouse RLF gene are encoded [21].
• Animal models support this hypothesis, and in particular INSL3 (Leydig insulin-like 3 hormone) has been proposed as putative gene for cryptorchidism, since male mice mutant for Insl3 exhibit bilateral abdominal cryptorchidism due to alteration of gubernaculum development [22].
• Sequence analysis in combination with mass spectrometry and tryptic peptide mapping showed unambiguously that RLF is larger than previously assumed and that it has the relaxin-type disulfide bond distribution that makes it a bona fide member of the relaxin family of hormones [23].
• Sequence analysis of bovine testicular and luteal RLF and cDNA shows that the same gene is expressed in both male and female gonads [24].

References