The role of the cytoskeleton in renal development

Genetic variants analysis of three dromedary camels using whole genome sequencing data

Whole genome wide identification and annotation of genetic variations in camels is in its first steps. The aim of this study was the identification of genome wide variants, functional annotations of them and enrichment analysis of affected genes using whole genome sequencing data of three dromedary camels. The genomes of two Iranian female dromedary camels that mostly used to produce meat and milk were sequenced to 41.9-fold and 38.6-fold coverage. A total of 4,727,238 single-nucleotide polymorphisms (SNPs) and 692,908 indels (insertions and deletions) were found by mapping raw reads to the dromedary reference assembly (GenBank Accession: GCA_000767585.1). In-silico functional annotation of the discovered variants in under study samples revealed that most SNPs (2,305,738; 48.78%) and indels (339,756; 49.03%) were located in intergenic regions. A comparison of the identified SNPs with those of the African camel (BioProject Accession: PRJNA269274) indicated that they had 993,474 SNPs in common. We found 15,168 non-synonymous SNPs in the shared variants of the three camels that could affect gene function and protein structure. Obtained results revealed that there were 7085, 6271 and 4688 non-synonymous SNPs among the 3436, 3058 and 2882 genes in the specific gene sets of Yazd dromedary, Trod dromedary and African dromedary, respectively. The list of genes predicted to be affected by non-synonymous variants in different individuals was subjected to gene ontology (GO) enrichment analysis.

miRNA let-7e targeting MMP9 is involved in adipose-derived stem cell differentiation toward epithelia

miRNA let-7e is involved in stem cell differentiation, and metalloproteinases are among its potential target genes. We hypothesized that the inhibitory action of let-7e on regulation of MMP9 expression could represent a crucial mechanism during differentiation of adipose-derived stem cells (ASCs). ASCs were differentiated with all-trans retinoic acid (ATRA) to promote differentiation, and the effect of let-7 silencing during differentiation was tested. Results indicate that ASCs cultured with ATRA differentiated into cells of the epithelial lineage. We found that ASCs cultured with ATRA or transfected with miRNA let-7e expressed epithelial markers such as cytokeratin-18 and early renal organogenesis markers such as Pax2, Wt1, Wnt4 and megalin. Conversely, the specific knockdown of miRNA let-7e in ASCs significantly decreased the expression of these genes, indicating its vital role during the differentiation process. Using luciferase reporter assays, we also showed that MMP9 is a direct target of miRNA let-7e. Thus, our results suggest that miRNA let-7e acts as a matrix metalloproteinase-9 (MMP9) inhibitor and differentiation inducer in ASCs.

Osmotic regulation of renal betaine transport: transcription and beyond

Cells in the kidney inner medulla are routinely exposed to high extracellular osmolarity during normal operation of the urinary concentrating mechanism. One adaptation critical for survival in this environment is the intracellular accumulation of organic osmolytes to balance the osmotic stress. Betaine is an important osmolyte that is accumulated via the betaine/gamma-aminobutyric acid transporter (BGT1) in the basolateral plasma membrane of medullary epithelial cells. In response to hypertonic stress, there is transcriptional activation of the BGT1 gene, followed by trafficking and membrane insertion of BGT1 protein. Transcriptional activation, triggered by changes in ionic strength and water content, is an early response that is a key regulatory step and has been studied in detail. Recent studies suggest there are additional post-transcriptional regulatory steps in the pathway leading to upregulation of BGT1 transport, and that additional proteins are required for membrane insertion. Reversal of this adaptive process, upon removal of hypertonic stress, involves a rapid efflux of betaine through specific release pathways, a reduction in betaine influx, and a slower downregulation of BGT1 protein abundance. There is much more to be learned about many of these steps in BGT1 regulation.

Central nervous system complications in renal transplant recipients in a tropical environment

Renal transplant recipients are at risk of developing various infectious and non-infectious complications affecting the central nervous system (CNS). There is paucity of data regarding the spectrum of CNS complications and the epidemiology of infective agents varies according to geographical location. We retrospectively studied the spectrum of CNS complications seen in 792 renal allograft recipients followed up at this tertiary care centre in north India over a 19-year period. Autopsy findings of 78 allograft recipients who died in the hospital were also reviewed and included. The brain was examined in 22 of these patients. Overall, 79 (10%) patients developed some form of CNS dysfunction with a mortality rate of 60.8%. CNS infections occurred in 31 renal allograft recipients (3.9% of total) and accounted for the largest group (39.2%). Fungi were the commonest etiological agents (21 patients) and were associated with a 70% mortality, with cryptococcal meningitis occurring in 12, mucormycosis in six, aspergillosis in one, and other unusual fungal infections in the remaining two patients. All patients with mucormycosis had a fatal outcome. The second largest group comprised of patients with non-uremic encephalopathies (23 patients, 29.1%) with metabolic encephalopathy occurring in 13, toxic encephalopathy in nine and hypertensive encephalopathy in one patient) and was associated with an overall mortality rate of 60.9%. Cerebrovascular accidents occurred in 12 patients (15.2%) and were associated with a mortality of 91.7%. Other CNS complications included treatment related complications in four (5.1%), primary CNS lymphomas in three (3.8%), and miscellaneous complications in six patients (7.6%). Patients with non-cryptococcal fungal infections of the CNS, hepatic and toxic encephalopathy and those with cerebrovascular accidents had the worst outcome. There was no relationship between the development of infection or stroke and the type of maintenance immunosuppression used. We conclude that complications involving the CNS occur in 10% of all renal transplant recipients and are associated a with high mortality, warranting early diagnosis and aggressive treatment.