Expanding the HPSE2 Genotypic Spectrum in Urofacial Syndrome, A Disease Featuring a Peripheral Neuropathy of the Urinary Bladder.

Urofacial (also called Ochoa) syndrome (UFS) is an autosomal recessive congenital disorder of the urinary bladder featuring voiding dysfunction and a grimace upon smiling. Biallelic variants in HPSE2, coding for the secreted protein heparanase-2, are described in around half of families genetically studied. Hpse2 mutant mice have aberrant bladder nerves. We sought to expand the genotypic spectrum of UFS and make insights into its pathobiology. Sanger sequencing, next generation sequencing and microarray analysis were performed in four previously unreported families with urinary tract disease and grimacing. In one, the proband had kidney failure and was homozygous for the previously described pathogenic variant c.429T>A, p.(Tyr143*). Three other families each carried a different novel HPSE2 variant. One had homozygous triplication of exons 8 and 9; another had homozygous deletion of exon 4; and another carried a novel c.419C>G variant encoding the missense p.Pro140Arg in trans with c.1099-1G>A, a previously reported pathogenic splice variant. Expressing the missense heparanase-2 variant in vitro showed that it was secreted as normal, suggesting that 140Arg has aberrant functionality after secretion. Bladder autonomic neurons emanate from pelvic ganglia where resident neural cell bodies derive from migrating neural crest cells. We demonstrated that, in normal human embryos, neuronal precursors near the developing hindgut and lower urinary tract were positive for both heparanase-2 and leucine rich repeats and immunoglobulin like domains 2 (LRIG2). Indeed, biallelic variants of LRIG2 have been implicated in rare UFS families. The study expands the genotypic spectrum in HPSE2 in UFS and supports a developmental neuronal pathobiology.

Mitochondria of human spermatozoa are preferentially susceptible to apoptosis.

Although elements of type I and II apoptosis have been demonstrated in human spermatozoa, their functionality has not been evaluated. The first dynamic studies revealed no type I apoptosis signal transduction via CD95. The aim of our study was to clarify whether type II apoptosis can be induced in human spermatozoa. Betulinic acid, a cytotoxic agent and highly specific inductor of type II apoptosis, acts by a direct effect on mitochondria. Motility, mitochondrial transmembrane potential, and active caspase-9 and -3 were examined in human ejaculated spermatozoa of 33 semen samples from healthy volunteers after incubation with 60 microg/mL betulinic acid for 10 and 60 min, respectively. Untreated aliquots of each sample served as negative controls. Treatment with betulinic acid resulted in the induction of type II apoptosis measured by disruption of mitochondrial transmembrane potential and activation of caspase-9 and -3. The loss of mitochondrial energy supply resulted in a significant decrease of spermatozoal motility and velocity. In spermatozoa, mitochondria are tightly packed and located exclusively in the midpiece region. This might contribute to their susceptibility against the induction of type II apoptosis and should be considered for therapeutic interventions and might have a future in the development of advanced birth control methods.