Aetiology of mixed gonadal dysgenesis (MGD) has not been completely elucidated. Molecular analyses have failed to demonstrate the presence of mutations in sex-determining region on Y chromosome (SRY); it has been suggested that these individuals may bear mutations in other genes involved in the testis-determining pathway. Desert hedgehog's (DHH) importance regarding male sex differentiation has been demonstrated in various studies we describe here, for the first time, two cases of MGD in which a monoallelic single base deletion in DHH is associated with the disorder. Genomic DNA was isolated from paraffin-embedded gonad tissue from 10 unrelated patients with MGD and three controls; in addition to, DNA from peripheral blood leukocytes in 100 controls. Coding sequence abnormalities in DHH were assessed by exon-specific PCR, single-stranded conformation polymorphism (SSCP) and direct sequencing. In two patients, a heterozygous 1086delG in exon 3 was found. Comparing previously described mutations in DHH to the one observed in this study, we can affirm that the phenotypic spectrum of patients with gonadal dysgenesis due to mutations in DHH is variable. This study continues to demonstrate the importance that DHH has in mammalian male sexual differentiation, providing extended evidence that DHH constitutes a key gene in gonadal differentiation.
"All known hedgehog proteins are synthesized as prepro-proteins , whose signal peptide is removed during their traffic through the endoplasmic reticulum, followed by an autocatalytic cleavage into an N-terminal domain (DHH-N), and a C-terminal domain (DHH-C) implicated in the autoproteolysis reaction (Porter et al., 1996). Studies in animals show that Dhh is involved in testicular differentiation (Clark et al., 2000; Pierucci-Alves et al., 2001; Yao et al., 2002; Kawai et al., 2011), and that this function is conserved among mammals (O'Hara et al., 2011); besides, mutations have been described in this gene in individuals with 46,XY PGD (Umehara et al., 2000; Canto et al., 2004; Das et al., 2011; Paliwal et al., 2011) and MGD (Canto et al., 2005). However, DHH is the signaling molecule of the HH family least-studied since; so far, there are only five reports of mutations in this gene and there are no functional studies of mutated DHH proteins. "
[Show abstract][Hide abstract] ABSTRACT: Mutations of Desert hedgehog (DHH) have been associated to 46,XY pure gonadal dysgenesis (PGD) and to mixed gonadal dysgenesis (MGD); however, there have been no functional studies of mutations described in DHH. To determine if mutations p.L162P and Δ1086delG yield functional impairment, we performed in vitro and in silico analysis of both DHH mutants. In complementary DNA of DHH, we performed site-directed mutagenesis, which was confirmed by DNA sequencing. Protein extracts were obtained from HEK293cells transfected with different constructs and analyzed by Western blot; besides, densitometric analysis of chemiluminescent signals was performed. In addition, the structure of the wt-DHH and its two mutant proteins was inferred using in silico protein molecular modeling. In the Western blot analysis, we observed the absence of signal for p.L162P in DHH-N and a diminished signal for Δ1086delG in DHH-C, when compared to wt-DHH. Protein modeling showed notable conformational changes for the side chains of p.L162P, while the secondary structure was drastically modified in Δ1086delG, when compared to wt-DHH. To our knowledge, this is the first study focused to determine by in vitro studies, the effect of two specific mutations in DHH associated with 46,XY PGD and MGD. Our results suggest that both mutations have a deleterious effect on the expression of the DHH mutant proteins.
DNA and cell biology 06/2013; 32(9). DOI:10.1089/dna.2013.2052 · 2.06 Impact Factor
"Over the past decade, molecular defects have been identified in all three paralogous genes of the prototypical Drosophila melanogaster hedgehog gene (hh) typically present in higher animals, such as humans: INDIAN HEDGEHOG (IHH with autosomal dominant Brachydactyly A-1, BDA1; MIM# 112500 and the autosomal recessive disorder acrocapitalfemoral dysplasia, ACFD; MIM# 607778; Gao et al., 2001; McCready et al., 2002; Liu et al., 2006; Lodder et al., 2008; reviewed in Byrnes et al., 2009), DESERT HEDGEHOG (DHH with gonadal dysgenesis; MIM# 605423; Umehara et al., 2000; Canto et al., 2004, 2005) and SONIC HEDGEHOG (with HPE and related disorders, see above). "
[Show abstract][Hide abstract] ABSTRACT: Mutations within either the SHH gene or its related pathway components are the most common, and best understood, pathogenetic changes observed in holoprosencephaly patients; this fact is consistent with the essential functions of this gene during forebrain development and patterning. Here we summarize the nature and types of deleterious sequence alterations among over one hundred distinct mutations in the SHH gene (64 novel mutations) and compare these to over a dozen mutations in disease-related Hedgehog family members IHH and DHH. This combined structural analysis suggests that dysfunction of Hedgehog signaling in human forebrain development can occur through truncations or major structural changes to the signaling domain, SHH-N, as well as due to defects in the processing of the mature ligand from its pre-pro-precursor or defective post-translation bi-lipid modifications with palmitate and cholesterol.
Human Mutation 10/2009; 30(10):E921-35. DOI:10.1002/humu.21090 · 5.14 Impact Factor
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