FAM40A In Pocytes And Its Influence On Cytoskeleton

Podocyte is a kind of glomerular epitheliar cell, which together with the glomerularbasement membrane (GBM), cell surface protein fenestrated glomerular endothelial cells,endothelial polysaccharide and podocyte zone together constitute the glomerular filtrationbarrier. More and more studies showed that Sertoli cell has an important position in thedevelopment of kidney disease.Podocyte disease is a kind of disease resulting from the abnormal kidney glomerularunits in Sertoli cell, is an important cause of proteinuria. In2002Pollak first use "ofpodocyte disease (podocytopathies)" this noun, the patients with glomerular podocytenumber and (or) density decreased, basement membrane thickening, change matrixcomponents of glomerular and fusion of foot process characterized by glomerular diseaseknown as foot cell disease. Classic podocyte diseases include minimal change nephropathyand focal segmental glomerulosclerosis.Focal segmental glomerulosclerosis (FSGS) is the focal and segmental distributioncaused by glomerular sclerosis and podocyte foot process fusion or degenerationdisappeared as the main pathological features of primary glomerular disease. The clinicalmanifestations of proteinuria, edema, hypertension and renal insufficiency, a considerablenumber of patients is not sensitive to the hormone and immunosuppressive drug therapy,renal function was worse, eventually progress to end-stage renal disease (end-stage renaldisease, ESRD). Foreign reports of adult renal biopsy, FSGS accounted for glomerulardisease in black15-20%, even as high as64%; the domestic data display, FSGS accountsfor renal biopsy of primary glomerular disease6%. In recent years, the data show that theincidence of FSGS is increasing year by year, to study its pathogenesis and treatment hasbeen a hotspot.According to the cause， FSGS can be divided into primary, secondary and familialFSGS. Familial focal segmental glomerulosclerosis (FFSGS) can be regarded as a specialtype of FSGS, due to the limitations of clinical diagnosis difficult by demographic anddiagnostic measures, the actual incidence rate is not low, according to the country report18%FSGS is related to gene mutation, familial genetic background. In recent twenty years,people study on familial FSGS, found many in podocytes and the cleft between themutation protein diaphragm, these functional protein most of the podocyte cytoskeletonand the integrity of the slit diaphragm maintains, is very important. Based on research and laboratory data, the loss of podocyte function integrity orchange is crucial in the development and progression of FSGS. FSGS as a typical podocytelesion, the damage can occur in a number of areas, including cytoskeleton, the destructionof nuclear transcription factor, the abnormal intracellular mitochondrial energy product ofabnormal intracellular calcium ion stability, dynamic change and slit diaphragm and othercomponents of the anomaly, which effect of functional change of podocyte cytoskeletalstructure on podocyte maximum. The cytoskeleton is an important component ofeukaryotic cells to maintain life activities, including the microfilaments, microtubules andintermediate filaments. Among them, is composed of actin microfilaments, actin-bindingprotein and myosin three. In podocytes, microfilament structure with actin as the basis,andα-actinin-4, Synaptopodin and myosin, together with fine adjustment and contractionof the podocyte actin cytoskeleton.Genetic studies of our research group for many years committed to the family ofFSGS family, early we find familial FSGS home is a5generation of54members, bylinkage analysis and sequencing of exons and further within-family filtering screening, hasinitially identified the pathogenic gene is FAM40A, and on this basis to successfully applyfor the two national Natural Science Fund (project on the continuous support surface).Sequence analysis and biological information on FAM40A analysis found that: it has21exons, encoding a protein of837amino acids, which contains3predictedtransmembrane domains, and can be combined with DNA, presumably as a protein threetimes across the nuclear envelope. The rich-proline N-based terminal, we conclude thatthe can protein and SH3domain containing direct combination play a specific function.Literature review: FAM40A is also known as STRIP1(striatin interacting protein1). Itcan encode STRIPAK (striatin-interacting phosphatase and kinase) is a core proteincomplexes. The latest report of FAM40A reported in literature: FAM40A plays animportant role in the regulation of cell morphology and cell skeleton extending dynamicchanges. The level of the gene expression changes may affect the cell distribution and cellmigration, actin filament shape.Preliminary experiments we found: immunohistochemical (IHC) staining method,visible FAM40A in normal rat glomerular podocytes, parietal epithelial cells and collectingduct cells are expressed; and preliminary in the same typical podocyte lesion and easy toprogress to FSGS membrane of renal disease (MCD) rat model (PHN) and minimalchange nephropathy (MCD) rat model (PAN), the FAM40A was observed. In conclusion, FAM40A may be closely related to FSGS, a crucial role to play in FSGS occurrence,development.In this study, students study will be completed in vitro order part of the first phasecontent: by in vitro culture of permanent mouse podocytes biochemical, combined beforewe on the bioinformatics analysis of FAM40A, and observe its expression and localizationin mouse podocytes on; followed by siRNA silencing technology application, constructionof Sertoli cell model of FAM40A silencing, effect on podocyte cytoskeleton to observe itssilencing (key observation of F-actin in cellular localization and distribution). The resultsshow: FAM40A is expressed in the kidney podocytes in mice, the expression andlocalization of mainly in the cytoplasm and nucleus nucleus surrounded by. Comparedwith the control group, the foot cell model is silent in the FAM40A protein, has changedthe distribution of F-actin, the main to the cell periphery distribution increased, and centralregion of cytoplasm reduced obviously distribution; and, at the same time with cellularprocesses such as cell morphological change was significantly reduced in thedifferentiation and maturation podocytes.This part of the experiment preliminarily determined the deletion of FAM40A has asignificant effect on the distribution of F-actin, and also affected the normal form ofpodocyte, initially identified FAM40A has some regulatory role in podocyte cytoskeleton,for the further study of FAM40A mutation in FSGS pathogenicity to lay the foundation.