MON-712 Restoration of Growth and Fertility in Zebrafish (Danio Rerio) Model with PROP1 Knockout Generated by CRISPR/Cas9 Genomic Editing

Introduction: Hypopituitarism is defined as the deficiency of one or more pituitary hormones and can occur due to pathogenic allelic variants in transcription factors involved in pituitary development. PROP1 gene is responsible for progenitor cell migration from the marginal zone to the anterior lobe, and its terminal differentiation into corticotropes and gonadotropes cell lines besides somatotropes, lactotropes and thyrotropes due to POU1F1 (also known as PIT1) activation. In humans, mutations in the PROP1 gene are the most common cause of congenital hypopituitarism with GH, TSH, LH/FSH, and progressive ACTH deficiencies. A dwarf phenotype with short stature, pituitary hormone deficiency, and infertility has been described in humans and Ames mice lineage harboring mutations in the PROP1/Prop1 gene. Another valuable animal model used in basic research is the zebrafish (Danio rerio) due to a high homology in neuroendocrine functioning. To test the potential of this model, in our previous study, a 32bp insertion carrying a stop codon was directed into the second exon of prop1 with CRISPR/Cas9, establishing a homozygous mutant strain (prop1mut). Objective: To characterize the phenotype and expression patterns of transcription factors and hormones in the zebrafish prop1mut lineage. Methods: prop1, pit1, and gh1 mRNA levels were analyzed during embryonic development at 24 and 72 hours post-fertilization (hpf). RNA from 30 pooled embryos was extracted using DirectZol RNA Miniprep. cDNA was synthesized from 1ug of total RNA using High-Capacity cDNA Reverse Transcription Kit and qPCR was performed using SYBR Green PCR Master Mix. Gene expression was normalized to ef1a and the prop1mut group was compared with the control wild type group (WT). Animals were kept in the tanks at a density of 15 animals/liter and images were acquired at 13 and 20 days post fertilization (dpf) after brief anesthetization using a stereomicroscope and measured in ImageJ software to determine the larval standard length from nose to the end of the spinal cord. Results: At 24 and 72hpf, prop1mut embryos expressed the altered prop1 mRNA at similar levels to the prop1 expression observed in WT. Lower pit1 expression in prop1mut embryos was observed at both periods (p<0.01). Albeit in low levels, similar gh1 expression was observed in both lineages at 24hpf, and prop1mut embryos presented lower gh1 expression at 72hpf (p<0.001). prop1mut larvae presented a significant decrease in size at 13dpf (p<0.001) but not at 20dpf. Conclusion: In this study, the prop1mut zebrafish model exhibited a dwarf phenotype during larval development associated with diminished pit1 and gh1 expression during the embryonic stage. Additionally, in the juvenile stage, the development rate in prop1mut animals was restored, presenting similar standard lengths observed in WT animals.

A Large PROP1 Gene Deletion in a Turkish Pedigree

Pituitary-specific paired-like homeodomain transcription factor, PROP1, is associated with multiple pituitary hormone deficiency. Alteration of the gene encoding the PROP1 may affect somatotropes, thyrotropes, and lactotropes, as well as gonadotropes and corticotropes. We performed genetic analysis of PROP1 gene in a Turkish pedigree with three siblings who presented with short stature. Parents were first degree cousins. Index case, a boy, had somatotrope, gonadotrope, thyrotrope, and corticotrope deficiency. However, two elder sisters had somatotroph, gonadotroph, and thyrotroph deficiency and no corticotroph deficiency. On pituitary magnetic resonance, partial empty sella was detected with normal bright spot in all siblings. In genetic analysis, we found a gross deletion involving PROP1 coding region. In conclusion, we report three Turkish siblings with a gross deletion in PROP1 gene. Interestingly, although little boy with combined pituitary hormone deficiency has adrenocorticotropic hormone (ACTH) deficiency, his elder sisters with the same gross PROP1 deletion have no ACTH deficiency. This finding is in line with the fact that patients with PROP1 mutations may have different phenotype/genotype correlation.

Clinical and genetic features of patients with multiple anterior pituitary hormone deficiency caused by mutations in the PROP1 gene; the efficacy of recombinant growth hormone therapy

Rationale. One of the most common causes of multiple anterior pituitary hormone deficiency (MPHD) is genetic defects in the PROP1 gene. PROP1 deficiency leads to malfunction of somatotrophs, lactotrophs, thyrotrophs, corticotrophs, and gonadotrophs. Now, there is an opportunity to conduct large-scale population studies of patients with genetic MPHD, describe their clinical and genetic heterogeneity, and evaluate the efficacy of long-term therapy of these patients with a recombinant growth hormone (rGH). Aim. The study aim was to assess the spectrum of PROP1 gene mutations in the Russian population of MPHD patients, rate and expected age of hypopituitarism components, and efficacy of rGH therapy. Material and methods. We analyzed the data of 27 patients diagnosed with MPHD and genetically confirmed mutations in the PROP1 gene who were treated at the Institute of Pediatric Endocrinology of the Endocrinology Research Center (ERC) in 1978―2016. MPHD was diagnosed based on laboratory data and stimulatory tests characterizing the functional activity of the pituitary gland. The molecular genetic study was performed using high-performance parallel sequencing. We used a custom Ampliseq_HP primer panel developed at the Department of Hereditary Endocrinopathies of the ERC, which included coding regions of the following genes: ARNT2, GH1, GHRH, GHRHR, GHSR, GLI2, HESX1, LHX3, LHX4, OTX2, PAX6, POU1F1, PROP1, SHH, SOX2, and SOX3. All patients received rGH therapy at a growth-stimulating dose from the time of GH deficiency diagnosis until final height completion. We evaluated the efficacy of therapy by comparing the achieved final height with the genetically expected one. Results. Non-familial cases prevailed (N=23) in the study cohort of patients with MPHD caused by mutations in the PROP1 gene; only two patients were monochorionic twin sisters; the other two patients were siblings. An analysis of the distribution of PROP1 gene mutations revealed a hot-point mutation c.301_302delAG in 24 patients (89%, 95% CI 71%; 98%). A mutation in the c.150delA locus occurred in 11 patients (41%, 95% CI 22%; 61%). Two patients had other mutations (c.629delC and c.43_49delGGGCGAG). Total GH deficiency was detected in all patients. The rate of secondary hypothyroidism (SHT) in patients of the study sample was 78% (95% CI 58%; 91%) at the time of diagnosis of GH deficiency and 100% (95% CI 81%; 100%) at the time of final height. The rate of secondary hypogonadism (SHG) at the time of final height was 100% (95% CI 81%; 100%), and the rate of secondary hypocorticism (SHC) was 41% (95% CI 22%; 61%). The normal level of prolactin was detected in 83% (95% CI 65%; 94%) of patients. At the time of growth plate closure, patients receiving rGH therapy at the growth-stimulating dose achieved the genetically expected final height. Conclusion. According to our findings, the most common mutation in the PROP1 gene is a deletion of AG nucleotides in the 101 codon (c.301_302 delAG), which is found in 89% (95% CI 71%; 98) patients. Patients with MPHD caused by mutations in the PROP1 gene have total GH deficiency and are diagnosed with secondary hypothyroidism and secondary hypogonadism in 100% of cases. The possibility of delayed manifestation of hypopituitarism components requires regular screening of tropic hormone levels for the timely start of substitution therapy and prevention of life-threatening conditions. rGH therapy is highly effective for GH deficiency caused by PROP1 gene mutations and allows patients to achieve the genetically expected height in the case of early diagnosis of growth hormone deficiency.

Hypopituitarism due to mutation in the PROP1 gene in association with the 47,XYY karyotype and autosomal dominant atrioventricular septal defect: two case reports

Application of genetic analysis in clinical practice enables identifying a combination of two rare diseases in one patient. We report two cases of patients with hypopituitarism due to PROP1 gene mutations in combination with the 47,XYY karyotype (case 1) and autosomal dominant partial atrioventricular septal defect (case 2). These clinical cases clearly demonstrate that several rare diseases can be present in one patient. The morphology of the pituitary gland has specific features in patients with a PROP1 gene mutation: signal inversion on T1- and T2-weighted images, as well as changes in size of the pituitary gland over time. In case of short stature, the hormonal evidence of secondary hypopituitarism, low IGF-1 levels, and specific morphological features observed in MRI images, we recommended carrying out molecular genetic analysis of the PROP1 gene without conducting growth hormone stimulation test.

Characterization of Exon 3 of PROP1 gene and Screening of H173R polymorphism in Karan Fries bulls

Present study was done in thirty Karan Fries bulls to characterize the Exon 3 of PROP1 gene and to screen for the H173R polymorphism as well as other variations including reported and novel SNPs in the targeted region. The exon 3 was characterized by sequencing the amplicons obtained after PCR amplification using custom designed primers. The BLAST analysis of the obtained sequence yielded 100% and 99% homology with sequences of Bos taurus and bison respectively. The multiple alignment of the target region sequence with Bos taurus reference sequence revealed that the bulls under the study were free of H173R mutations. No variations were observed thus giving the targeted region a highly conserved one.