Cytogenetic evaluation of patients with clinical spectrum of Turner syndrome

Aim: The objective of this study was to correlate the genotype, of female patients, withshort stature and primary amenorrhea. Materials and Methods: One hundred and forty-six subjects were recruited during 2005-2012. Microscopic and automated karyotyping analyses were done by using chromosomes isolated from the lymphocytes using Giemsa banding (GTG) to identify chromosome abnormalities. Results: A total of 146 clinically suspected Turner syndrome (TS) subjects were recruited for the study, of which, 61 patients were identified to have chromosome abnormalities. The chromosomal abnormalities detected were as follows: Monosomy X (n = 19, 13.01%), triple X syndrome (n = 4, 2.7%), mosaic TS (n = 12, 8.21%), XY gonadal dysgenesis (n = 13, 8.9%), and structural abnormalities including X chromosome (n = 15, 10.27%) and one patient each with autosomal changes involving 9qh inversion and translocation of chromosomes 12 and 14. Conclusion: Karyotype abnormalities accounting for 46% in this study emphasize the need for karyotype testing in cases of short stature with primary amenorrhea

PIMT Controls Insulin Synthesis and Secretion through PDX1

Pancreatic beta cell function is an important component of glucose homeostasis. Here, we investigated the function of PIMT (PRIP-interacting protein with methyl transferase domain), a transcriptional co-activator binding protein, in the pancreatic beta cells. We observed that the protein levels of PIMT, along with key beta cell markers such as PDX1 (pancreatic and duodenal homeobox 1) and MafA (MAF bZIP transcription factor A), were reduced in the beta cells exposed to hyperglycemic and hyperlipidemic conditions. Consistently, PIMT levels were reduced in the pancreatic islets isolated from high fat diet (HFD)-fed mice. The RNA sequencing analysis of PIMT knockdown beta cells identified that the expression of key genes involved in insulin secretory pathway, Ins1 (insulin 1), Ins2 (insulin 2), Kcnj11 (potassium inwardly-rectifying channel, subfamily J, member 11), Kcnn1 (potassium calcium-activated channel subfamily N member 1), Rab3a (member RAS oncogene family), Gnas (GNAS complex locus), Syt13 (synaptotagmin 13), Pax6 (paired box 6), Klf11 (Kruppel-Like Factor 11), and Nr4a1 (nuclear receptor subfamily 4, group A, member 1) was attenuated due to PIMT depletion. PIMT ablation in the pancreatic beta cells and in the rat pancreatic islets led to decreased protein levels of PDX1 and MafA, resulting in the reduction in glucose-stimulated insulin secretion (GSIS). The results from the immunoprecipitation and ChIP experiments revealed the interaction of PIMT with PDX1 and MafA, and its recruitment to the insulin promoter, respectively. Importantly, PIMT ablation in beta cells resulted in the nuclear translocation of insulin. Surprisingly, forced expression of PIMT in beta cells abrogated GSIS, while Ins1 and Ins2 transcript levels were subtly enhanced. On the other hand, the expression of genes, PRIP/Asc2/Ncoa6 (nuclear receptor coactivator 6), Pax6, Kcnj11, Syt13, Stxbp1 (syntaxin binding protein 1), and Snap25 (synaptosome associated protein 25) associated with insulin secretion, was significantly reduced, providing an explanation for the decreased GSIS upon PIMT overexpression. Our findings highlight the importance of PIMT in the regulation of insulin synthesis and secretion in beta cells