👤 R Melis

Sleep deprivation (SD) impairs information processing through alterations of prefrontal cortex (PFC) function, yet the molecular underpinnings of this process remain poorly understood. We previously showed that SD disrupts sensorimotor gating by elevating prefrontal levels of the neurosteroid allopregnanolone (AP), a positive allosteric modulator of GABA-A receptors. Here we identify a complementary, mechanistically independent process whereby SD alters GABA-A currents in the PFC of mice and rats. SD reduced membrane expression of the chloride exporter KCC2, leading to intracellular chloride accumulation and a depolarizing shift in GABA-A receptor reversal potential that weakened GABAergic inhibition. Pharmacological normalization of chloride homeostasis with bumetanide fully rescued SD-induced deficits in sensorimotor gating and information encoding. SD also upregulated BDNF, and intra-PFC antagonism of its receptor TrkB restored KCC2 expression and normalized information processing, identifying BDNF-TrkB signaling as an upstream driver of chloride dysregulation. Notably, blocking AP synthesis rescued behavioral deficits without correcting chloride imbalance, confirming mechanistic independence. Finally, combined administration of AP and a KCC2 blocker produced information-processing deficits akin to those induced by SD. These findings identify TrkB-dependent disruption of prefrontal chloride homeostasis as a druggable mechanism underlying sleep loss-induced cognitive dysfunction. Show less

Deficiency of 17β-hydroxysteroid dehydrogenase type 3 (17βHSD3), an enzyme converting androstenedione (A) to testosterone (T), is a rare cause of autosomal recessive 46,XY disorder of sexual development (DSD). A 18-years phenotypically female patient from southern Italy presented with primary amenorrhea. She had deep voice, macrocephaly, enlarged and bulbous nasal tip, macrostomia, facial acne, breast asymmetry, hypoplasia of the first finger of right hand, proximal implant of the fifth metatarsus bilaterally as well as an increased muscle mass and hirsutism, with hair distribution on face, neck, chest, abdomen, pubic region and on upper and lower limbs. Genital exam showed thickened labra majora with absence of labra minora and a blind-ending pseudo-vagina with clitoris enlargement. Karyotype analysis showed a male genotype (46,XY). Hormonal evaluation showed decreased T (188 ng/dL-6.5 nmol/L) and increased A (10 ng/mL-34,96 nmol/L), considering male reference ranges, resulting in a decreased T/A ratio (0,186). MRI identified testicles in inguinal regions. Human Chorionic Gonadotropin test showed T/A ratio permanently under 0,8. These evidences were suggestive of a 46,XY DSD due to 17βHSD3 deficiency. An homozygous mutation (IVS3 -1 G>C or c.326-1G>C) of the 17βHSD3 gene was discovered. Psychologist identified a well determined female gender identity. It was decided to proceed with gonadectomy and vaginal enlargement by use of dilatators. The case described represents a new case of DSD due to 17βHSD3 deficiency. This patient, raised as a girl, is diagnosed in a very late stage. The identified mutation, previously reported only in Dutch and Brazilian population, is one of 27 presently known mutations of 17βHSD3 gene and is never reported in Italian population. Show less

The discs-large family is a collection of proteins that have a common structural organization and are thought to be involved in signal transduction and mediating protein-protein interactions at the cytoplasmic surface of the cell membrane. The defining member of this group of proteins is the gene product of the Drosophila lethal (1) discs large (dlg) 1 locus, which was originally identified by the analysis of recessive lethal mutants. Germline mutations in dlg result in loss of apical-basolateral polarity, disruption of normal cell-cell adhesion, and neoplastic overgrowth of the imaginal disc epithelium. We have isolated and characterized a novel human gene, DLG3, that encodes a new member of the discs-large family of proteins. The putative DLG3 gene product has a molecular weight of 66 kDa and contains a discs-large homologous region, a src oncogene homology motif 3, and a domain with homology to guanylate kinase. The DLG3 gene is located on chromosome 17, in the same segment, 17q12-q21, as the related gene, DLG2. The products of the DLG2 and DLG3 genes show 36% identity and 58% similarity to each other, and both show nearly 60% sequence similarity to p55, an erythroid phosphoprotein that is a component of the red cell membrane. We suggest that p55, DLG2, and DLG3 are closely related members of a gene family, whose protein products have a common structural organization and probably a similar function. Show less