Diabeedi kujunemine, fertiilsuse ja energia ainevahetuse häired Wfs1 puudulikkusega hiirel kui Wolframi sündroomi loommudelil

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Wolframi sündroom (WS) on autosoom-retsessiivse pärandumismustriga neurodegeneratiivne haigus, mille peamisteks kliinilisteks avaldusteks on varases lapseeas algav 1. tüüpi diabeet, nägemisnärvi atroofia, magediabeet ja sensorineuraalne kuulmislangus. Lisaks võivad esineda ka urotrakti väärarendid, mitmed erinevad neuroloogilised ning psühhiaatrilised probleemid. Wolframi sündroomi põhjuseks on WFS1 geeni mutatsioon, mis paikneb 4. kromosoomi lühikeses õlas (4p16). Esimeseks kliiniliseks avalduseks WS korral on diabeet. Diabeet tekib WS haigetel keskmiselt 6-aastaselt, poistel pisut varem kui tüdrukutel. Võrreldes 1. tüüpi diabeediga esineb Wolframi sündroomiga patsientidel vähem mikrovaskulaarseid komplikatsioone, ketoatsidoosi ja ka insuliini vajadus on väiksem. Täpne diabeedi tekkemehhanism WS korral ei ole teada. Sageli kaasub WS-ga lühike kasv, mille üheks põhjuseks on leitud kasvuhormooni puudulikkus. Siiani puudub info WS-ga patsientide fertiilsusest. Meile teadaolevalt ei ole siiani uuritud WFS1 geeni rolli fertiilsuse mõjutamisel. Puuduvad ka andmed WS patsientide kilpnäärme funktsiooni ja energia ainevahetuse kohta. Meie eesmärgiks oli uurida diabeedi kujunemist ja selle võimalikke patofüsioloogilisi põhjuseid WS loommudelil – Wfs1 puudulikkusega hiirel. Samuti soovisime anda ülevaate isasloomade viljakusest ning leida võiamaliku viljatuse põhjuseid. Leidsime, et kasvuhäire ja diabeedi kujunemisel esinevad tõsised sugudevahelised erinevused. Kasvuhäire on Wfs1KO isashiirtel väljendunud juba sünnil, kusjuures emashiirtel kujuneb see alles esimeste elukuude jooksul. Mõlemast soost Wfs1KO hiirtel esineb väljendunud glükoosi tolerantsuse häire, kuid väljendunud diabeet koos madala plasma insuliini tasemega kujuneb ainult isashiirtel. Näitasime, et diabeedi tekkepõhjuseks Wfs1KO hiirtel pole mitte niivõrd primaarselt insuliini defitsiit, kuivõrd võimetus konverteerida mitteaktiivset proinsuliini aktiivseks insuliiniks. Näitasime, et mutatsiooniga isashiirte viljakus on langenud ja selle põhjuseks on testistes ja spermas esinevad morfoloogilised muutused. Leidsime histoloogilisi muutuseid ka isashiirte kilpnäärmetes, kuid need ei mõjuta oluliselt kilpnäärme funktsiooni. Samuti ei esine olulisi erinevuseid Wfs1-defitsiitsete hiirte energia ainevahetuses. Küll aga viitavad meie uuringutulemused ka võimalikule leptiini resistentsusele Wfs1KO emasloomadel, mille tõestamine vajab aga täiendavaid uuringuid.Wolfram syndrome (WS) is an autosomal recessive disorder usually diagnosed in childhood when non-autoimmune type I diabetes occurs with optic atrophy, cranial diabetes insipidus and sensorineural deafness. Also dilated renal outflow tracts, multiple neurological abnormalities and various neurological and psychiatric disorders can be present. The reason for WS is the mutation in the WFS1 gene. The exact mechanism of the development of the diabetes related to the WS is yet not known. Some data has shown that the onset of diabetes tends to occur earlier in boys than in girls. As yet there has been no data regarding the fertility of patients with WS. Previous studies have described anterior pituitary dysfunction and, in male patients, the presence of primary gonadal atrophy and hypergonadotropic hypogonadism. As far as we know, the role of the Wfs1 gene in fertility, as well as in thyroid function and in energy metabolism, has not been studied. The aim of the study was to describe the development of the diabetes, fertility and energy metabolism disturbances in an animal model of WS – Wfs1-deficient mouse. We showed that the fertility of male mutant mice is impaired and the reasons for that are the morphological changes in the testes and sperm. Sperm motility is not affected in Wfs1KO mice. There are severe sex-related differences in the development of growth failure and diabetes. Growth failure in male Wfs1KO mice is already present from birth, whereas in females it develops during the first months of life. Severe glucose intolerance developed in both sexes, but overt diabetes with low plasma insulin levels occurs only in male Wfs1KO mice. One of the reasons for developing WS related diabetes is not the insulin deficiency itself, but the impairment in converting proinsulin to active insulin. The energy metabolism did not differ significantly between Wfs1 KO and wt mice. Our data also suggest some degree of leptin resistance in female Wfs1KO mice, which needs to be confirmed in further studies

Male mice with deleted Wolframin (Wfs1) gene have reduced fertility

Background: Wolfram Syndrome (WS) is an autosomal recessive disorder characterised by non-autoimmune diabetes mellitus, optic atrophy, cranial diabetes insipidus and sensorineural deafness. Some reports have described hypogonadism in male WS patients. The aim of our study was to find out whether Wfs1 deficient (Wfs1KO) male mice have reduced fertility and, if so, to examine possible causes. Methods: Wfs1KO mice were generated by homologous recombination. Both Wfs1KO and wild type (wt) male mice were mated with wt female mice. The number of litters and the number of pups were counted and pregnancy rates calculated. The motility and morphology of the sperm and the histology of testes were analysed. Serum testosterone and FSH concentrations were also measured. Results: The pregnancy rate in wt females mated with Wfs1KO males was significantly lower than in the control group (15% vs. 32%; p < 0.05), but there was no significant difference in litter size. Analysis of male fertility showed that, in the Wfs1KO group, eight males out of 13 had pups whereas in the control group all 13 males had at least one litter. Sperm motility was not affected in Wfs1KO mice, but Wfs1KO males had less proximal bent tails (14.4 +/- 1.2% vs. 21.5 +/- 1.3 p < 0.05) and less abnormal sperm heads (22.8 +/- 1.8 vs. 31.5 +/- 3.5, p < 0.05) than wt males. Testes histology revealed significantly reduced number of spermatogonia (23.9 +/- 4.9 vs. 38.1 +/- 2.8; p < 0.05) and Sertoli cells (6.4 +/- 0.5 vs. 9.2 +/- 1.0; p < 0.05) in Wfs1KO mice. Serum testosterone and FSH concentrations did not differ between the two groups. Conclusion: The impaired fertility of Wfs1KO male mice is most likely due to changes in sperm morphology and reduced number of spermatogenic cells. The exact mechanism through which the Wfs1 gene influences sperm morphology needs to be clarified in further studies

Male mice with deleted Wolframin (Wfs1) gene have reduced fertility

Abstract Background Wolfram Syndrome (WS) is an autosomal recessive disorder characterised by non-autoimmune diabetes mellitus, optic atrophy, cranial diabetes insipidus and sensorineural deafness. Some reports have described hypogonadism in male WS patients. The aim of our study was to find out whether Wfs1 deficient (Wfs1KO) male mice have reduced fertility and, if so, to examine possible causes. Methods Wfs1KO mice were generated by homologous recombination. Both Wfs1KO and wild type (wt) male mice were mated with wt female mice. The number of litters and the number of pups were counted and pregnancy rates calculated. The motility and morphology of the sperm and the histology of testes were analysed. Serum testosterone and FSH concentrations were also measured. Results The pregnancy rate in wt females mated with Wfs1KO males was significantly lower than in the control group (15% vs. 32%; p Conclusion The impaired fertility of Wfs1KO male mice is most likely due to changes in sperm morphology and reduced number of spermatogenic cells. The exact mechanism through which the Wfs1 gene influences sperm morphology needs to be clarified in further studies.</p

Hypothalamic gene expression profile indicates a reduction in G protein signaling in the <i>Wfs1</i> mutant mice

The Wfs1 gene codes for a protein with unknown function, but deficiency in this protein results in a range of neuropsychiatric and neuroendocrine syndromes. In the present study we aimed to find the functional networks influenced by Wfs1 in the hypothalamus. We performed gene expression profiling (Mouse Gene 1.0 ST Arrays) in Wfs1-deficient mice; 305 genes were differentially expressed with nominal P value &lt; 0.01. FDR (false discovery rate)-adjusted P values were significant (0.007) only for two genes: C4b (t=9.66) and Wfs1 ( t = −9.03). However, several genes related to G protein signaling were very close to the FDR-adjusted significance level, such as Rgs4 (regulator of G protein signaling 4) that was downregulated (−0.34, t = −5.4) in Wfs1-deficient mice. Changes in Rgs4 and C4b expression were confirmed by QRT-PCR. In humans, Rgs4 is in the locus for bipolar disease (BPD), and its expression is downregulated in BPD. C4b is a gene related to the neurodegenerative diseases. Functional analysis including the entire data set revealed significant alterations in the canonical pathway “G protein-coupled receptor signaling.” The gene expression profile in the hypothalami of the Wfs1 mutant mice was significantly similar to the profiles of following biological functions: psychological disorders, bipolar disorder, mood disorder. In conclusion, hypothalamic gene expression profile resembles with some molecular pathways functionally related to the clinical syndromes in the Wolfram syndrome patients. </jats:p