Mapping of the minimal inorganic phosphate transporting unit of human PiT2 suggests a structure universal to PiT-related proteins from all kingdoms of life

<p>Abstract</p> <p>Background</p> <p>The inorganic (P_i) phosphate transporter (PiT) family comprises known and putative Na⁺- or H⁺-dependent P_i-transporting proteins with representatives from all kingdoms. The mammalian members are placed in the outer cell membranes and suggested to supply cells with P_ito maintain house-keeping functions. Alignment of protein sequences representing PiT family members from all kingdoms reveals the presence of conserved amino acids and that bacterial phosphate permeases and putative phosphate permeases from archaea lack substantial parts of the protein sequence when compared to the mammalian PiT family members. Besides being Na⁺-dependent P_i(NaP_i) transporters, the mammalian PiT paralogs, PiT1 and PiT2, also are receptors for gamma-retroviruses. We have here exploited the dual-function of PiT1 and PiT2 to study the structure-function relationship of PiT proteins.</p> <p>Results</p> <p>We show that the human PiT2 histidine, H₅₀₂, and the human PiT1 glutamate, E₇₀, - both conserved in eukaryotic PiT family members - are critical for P_itransport function. Noticeably, human PiT2 H₅₀₂is located in the C-terminal PiT family signature sequence, and human PiT1 E₇₀is located in ProDom domains characteristic for all PiT family members.</p> <p>A human PiT2 truncation mutant, which consists of the predicted 10 transmembrane (TM) domain backbone without a large intracellular domain (human PiT2ΔR₂₅₄-V₄₈₃), was found to be a fully functional P_itransporter. Further truncation of the human PiT2 protein by additional removal of two predicted TM domains together with the large intracellular domain created a mutant that resembles a bacterial phosphate permease and an archaeal putative phosphate permease. This human PiT2 truncation mutant (human PiT2ΔL₁₈₃-V₄₈₃) did also support P_itransport albeit at very low levels.</p> <p>Conclusions</p> <p>The results suggest that the overall structure of the P_i-transporting unit of the PiT family proteins has remained unchanged during evolution. Moreover, in combination, our studies of the gene structure of the human PiT1 and PiT2 genes (<it>SLC20A1 </it>and <it>SLC20A2</it>, respectively) and alignment of protein sequences of PiT family members from all kingdoms, along with the studies of the dual functions of the human PiT paralogs show that these proteins are excellent as models for studying the evolution of a protein's structure-function relationship.</p

Glutamate-system defects behind psychiatric manifestations in a familial hemiplegic migraine type 2 disease-mutation mouse model

Migraine is a complex brain disorder, and understanding the complexity of this prevalent disease could improve quality of life for millions of people. Familial Hemiplegic Migraine type 2 (FHM2) is a subtype of migraine with aura and co-morbidities like epilepsy/seizures, cognitive impairments and psychiatric manifestations, such as obsessive-compulsive disorder (OCD). FHM2 disease-mutations locate to the ATP1A2 gene encoding the astrocyte-located α(2)-isoform of the sodium-potassium pump (α(2)Na(+)/K(+)-ATPase). We show that knock-in mice heterozygous for the FHM2-associated G301R-mutation (α(2)(+/G301R)) phenocopy several FHM2-relevant disease traits e.g., by mimicking mood depression and OCD. In vitro studies showed impaired glutamate uptake in hippocampal mixed astrocyte-neuron cultures from α(2)(G301R/G301R) E17 embryonic mice, and moreover, induction of cortical spreading depression (CSD) resulted in reduced recovery in α(2)(+/G301R) male mice. Moreover, NMDA-type glutamate receptor antagonists or progestin-only treatment reverted specific α(2)(+/G301R) behavioral phenotypes. Our findings demonstrate that studies of an in vivo relevant FHM2 disease knock-in mouse model provide a link between the female sex hormone cycle and the glutamate system and a link to co-morbid psychiatric manifestations of FHM2

Dihydropyrimidine dehydrogenase (DPD) genotype and phenotype among Danish cancer patients: prevalence and correlation between <i>DPYD</i>-genotype variants and P-uracil concentrations

Dihydropyrimidine dehydrogenase (DPD) genotype and phenotype among Danish cancer patients: prevalence and correlation between DPYD-genotype variants and P-uracil concentration

Dihydropyrimidine dehydrogenase (DPD) genotype and phenotype among Danish cancer patients: prevalence and correlation between <i>DPYD</i>-genotype variants and P-uracil concentrations

Dihydropyrimidine dehydrogenase (DPD) genotype and phenotype among Danish cancer patients: prevalence and correlation between DPYD-genotype variants and P-uracil concentration

Dihydropyrimidine dehydrogenase (DPD) genotype and phenotype among Danish cancer patients: prevalence and correlation between DPYD-genotype variants and P-uracil concentrations

Dihydropyrimidine dehydrogenase (DPD) genotype and phenotype among Danish cancer patients: prevalence and correlation between DPYD-genotype variants and P-uracil concentration