Distinct effects on mRNA export factor GANP underlie neurological disease phenotypes and alter gene expression depending on intron content

Defects in the mRNA export scaffold protein GANP, encoded by the MCM3AP gene, cause autosomal recessive early-onset peripheral neuropathy with or without intellectual disability. We extend here the phenotypic range associated with MCM3AP variants, by describing a severely hypotonic child and a sibling pair with a progressive encephalopathic syndrome. In addition, our analysis of skin fibroblasts from affected individuals from seven unrelated families indicates that disease variants result in depletion of GANP except when they alter critical residues in the Sac3 mRNA binding domain. GANP depletion was associated with more severe phenotypes compared with the Sac3 variants. Patient fibroblasts showed transcriptome alterations that suggested intron content-dependent regulation of gene expression. For example, all differentially expressed intronless genes were downregulated, including ATXN7L3B, which couples mRNA export to transcription activation by association with the TREX-2 and SAGA complexes. Our results provide insight into the molecular basis behind genotype-phenotype correlations in MCM3AP-associated disease and suggest mechanisms by which GANP defects might alter RNA metabolism.

Association between Non-Alcoholic Steatohepatitis and Left Ventricular Diastolic Dysfunction in Type 2 Diabetes Mellitus

BACKGROUND

Impaired diastolic heart function has been observed in persons with non-alcoholic fatty liver disease (NAFLD) and/or with type 2 diabetes mellitus (T2DM). However, it is unclear whether NAFLD fibrotic progression, i.e., non-alcoholic steatohepatitis, poses an independent risk for diastolic dysfunction in T2DM. We investigated the association between liver fibrosis and left ventricular (LV) diastolic dysfunction in T2DM.

METHODS

We analyzed 606 patients with T2DM, aged ≥50 years, who had undergone liver ultrasonography and pulsed-wave Doppler echocardiography. Insulin sensitivity was measured by short insulin tolerance test. Presence of NAFLD and/or advanced liver fibrosis was determined by abdominal ultrasonography and NAFLD fibrosis score (NFS). LV diastolic dysfunction was defined according to transmitral peak early to late ventricular filling (E/A) ratio and deceleration time, using echocardiography.

RESULTS

LV diastolic dysfunction was significantly more prevalent in the NAFLD versus non-NAFLD group (59.7% vs. 49.0%, P=0.011). When NAFLD was stratified by NFS, subjects with advanced liver fibrosis exhibited a higher prevalence of diastolic dysfunction (49.0%, 50.7%, 61.8%; none, simple steatosis, advanced fibrosis, respectively; P for trend=0.003). In multivariable logistic regression, liver fibrosis was independently associated with diastolic dysfunction (odds ratio [OR], 1.58; 95% confidence interval [CI], 1.07 to 2.34; P=0.022) after adjusting for insulin resistance and cardiometabolic risk factors. This association remained significant in patients without insulin resistance (OR, 4.32; 95% CI, 1.73 to 11.51; P=0.002).

CONCLUSIONS

Liver fibrosis was associated with LV diastolic dysfunction in patients with T2DM and may be an independent risk factor for diastolic dysfunction, especially in patients without systemic insulin resistance.

Therapeutic Effect of a Novel Chimeric Molecule Targeting Both Somatostatin and Dopamine Receptors on Growth Hormone-Secreting Pituitary Adenomas

BACKGROUND

Acromegaly is a rare disease primarily caused by growth hormone (GH)-secreting pituitary adenomas, and its treatment is costly. Moreover, some patients are unresponsive to treatment. Hence, there are increasing efforts to develop new drugs with improved effectiveness for this disease. BIM23B065 is a novel chimeric molecule that acts on both somatostatin and dopamine receptors. This study aimed to investigate the effects of BIM23B065 compared with those of a somatostatin receptor analog and a dopamine agonist.

METHODS

The effects of BIM23B065 on the proliferation, GH and insulin-like growth factor-1 (IGF-1) levels, and extracellular signal-regulated kinase (ERK) 1/2 and cyclic AMP response element binding (CREB) phosphorylation of GH3 cells were investigated with MTS assay, enzyme-linked immunosorbent assay, and Western blotting, respectively. The dosage and treatment duration of BIM23B065 were tested in animal models of GH-secreting pituitary adenoma. The effect of BIM23B065 (3 mg/kg/day) on changes in IGF-1 levels before and after treatment was further investigated.

RESULTS

In vitro, BIM23B065 treatment decreased GH release in the culture media and downregulated ERK 1/2 and CREB phosphorylation to 22% and 26%, respectively. In vivo, IGF-1 expression decreased to 50 % after 4 weeks of treatment with BIM23B065 using an osmotic pump implant. Moreover, magnetic resonance imaging results showed that the tumor size decreased significantly following treatment with BIM23B065 for 4 weeks.

CONCLUSION

The novel chimeric molecule was effective in decreasing IGF-1 and GH levels and may serve as an effective therapeutic agent for acromegaly.

Evogliptin, a Dipeptidyl Peptidase-4 Inhibitor, Attenuates Renal Fibrosis Caused by Unilateral Ureteral Obstruction in Mice

Renal fibrosis is considered to be the final common outcome of chronic kidney disease. Dipeptidyl peptidase-4 (DPP-4) inhibitors have demonstrated protective effects against diabetic kidney disease. However, the anti-fibrotic effect of evogliptin, a DPP-4 inhibitor, has not been studied. Here, we report the beneficial effects of evogliptin on unilateral ureteral obstruction (UUO)-induced renal fibrosis in mice. Evogliptin attenuated UUO-induced renal atrophy and tubulointerstitial fibrosis. Immunohistochemistry and Western blotting demonstrated that evogliptin treatment inhibits pro-fibrotic gene expressions and extracellular matrix production. In vitro findings showed that the beneficial effects of evogliptin on renal fibrosis are mediated by inhibition of the transforming growth factor-β/Smad3 signaling pathway. The present study demonstrates that evogliptin is protective against UUO-induced renal fibrosis, suggesting that its clinical applications could extend to the treatment of kidney disease of non-diabetic origin.