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Background: Recent advances in comprehensive gene analysis revealed the heterogeneity of mouse lung fibroblasts. However, direct comparisons between these subpopulations are limited due to challenges in isolating target subpopulations without gene-specific reporter mouse lines. In addition, the properties of lung lipofibroblasts remain unclear, particularly regarding the appropriate cell surface marker and the niche capacity for alveolar epithelial cell type 2 (AT2), an alveolar tissue stem cell. Methods and results: Using cell surface markers applicable even into wild-type mouse lungs, we could classify PDGFRα+ total lung resident fibroblasts into at least two major distinct subpopulations: integrin α8 (ITGA8)+ and SCA-1+ fibroblasts. We analyzed their characteristics, including lipid content, transcriptome profiles, and alveolar stem cell niche capacity. ITGA8+ fibroblasts showed higher positivity of intracellular lipid droplets compared to SCA-1+ fibroblasts (91.0 ± 1.5% vs. 5.0 ± 0.5% in LipidTOX staining; 91.3 ± 1.4% vs. 7.1 ± 1.7% in Oil Red O staining). The fluorescence intensity of LipidTOX in the ITGA8+ fibroblasts was highest in newborn compared to adult or aged lungs. The transcriptome profile of ITGA8+ fibroblasts in adult mouse lungs, evaluated through two independent single-cell RNA-seq datasets, consistently showed higher expression of Tcf21 and Plin2, which are canonical markers of lipofibroblasts. ITGA8+ fibroblasts were primarily located in the alveolar area, particularly in the neighborhood of AT2. Compared to SCA-1+ fibroblasts, ITGA8+ fibroblasts showed higher mRNA expression of potential AT2-supportive factors, Fgf10, Fgf7, and Wnt2, but unexpectedly, exhibited lower efficiency in alveolar organoid formation. Conclusions: ITGA8+ lung fibroblasts correspond to alveolar lipofibroblasts, but the alveolar niche capacity may be lower than SCA-1+ lung fibroblasts. Further studies are necessary for the functional distinction between lung fibroblast subpopulations. [ABSTRACT FROM AUTHOR]

Kidney failures in infants are mostly caused by congenital anomalies of the kidney and urinary tract (CAKUT), which are among the most common congenital birth disorders worldwide when paired with cardiac abnormalities. People with CAKUT often have severe kidney failure as a result of a wide range of abnormalities that can occur alone or in conjunction with other syndromic disorders. In this study, we aimed to investigate the expression pattern of CAKUT candidate genes alpha-8 integrin (ITGA8) and Van Gogh-like 2 (VANGL2) in fetal tissues of healthy and CAKUT-affected kidneys using immunohistochemistry and immunofluorescence. We found that under CAKUT circumstances, the expressions of ITGA8 and VANGL2 are changed. Additionally, we showed that VANGL2 expression is constant during fetal aging, but ITGA8 expression varies. Moreover, compared to normal healthy kidneys (CTRL), ITGA8 is poorly expressed in duplex kidneys (DKs) and dysplastic kidneys (DYS), whereas VANGL2 is substantially expressed in dysplastic kidneys (DYS) and poorly expressed in hypoplastic kidneys (HYP). These results point to VANGL2 and ITGA8 as potential prognostic indicators for CAKUT malformations. Further research is necessary to explore the molecular mechanisms underlying this differential expression of ITGA8 and VANGL2. [ABSTRACT FROM AUTHOR]

Integrins are closely related to the occurrence and development of tumors. ITGA8 encodes the alpha 8 subunit of the heterodimeric integrin alpha8beta1. Studies on the role of this gene in the occurrence and development of lung cancer are scarce. The examination of public databases revealed that ITGA8 expression was significantly lower in tumor tissue than that in normal tissue, especially in lung cancer, renal carcinoma, and prostate cancer. Survival analysis of patients with lung adenocarcinoma revealed that higher ITGA8 expression had better prognosis. ITGA8 was positively related to immune checkpoints and immunomodulators, whereas B cell, CD4+ T cell, CD8+ T cell, neutrophil, macrophage, and dendritic cell infiltration had the same correlation. Moreover, ITGA8 was negatively related to cancer stemness. We used an online database to predict the miRNAs and lncRNAs that regulate ITGA8 and obtained the regulatory network of ITGA8 through correlation analysis and Kaplan-Meier survival analysis. Quantitative real-time PCR and western blot analyses showed that LINC01798 regulates ITGA8 expression through miR-17- 5p. Therefore, the regulatory network of ITGA8 may serve as a new therapeutic target to improve the prognosis of patients with lung cancer. [ABSTRACT FROM AUTHOR]

Integrin Subunit Alpha 8 gene (ITGA8) encodes an integrin chain that is known to be critical in the early stage of the kidney development. Bi‐allelic pathogenic variants in ITGA8 are associated with bilateral renal agenesis, as well as anomalies involving urogenital system. Here, we report two unrelated patients presenting with slowly progressing chronic kidney disease associated with bilateral renal hypodysplasia carrying homozygous loss of function variants in the ITGA8 gene. These results broaden the clinical and genotypic spectrum of ITGA8 defects, revealing the high and unexpected degree of phenotypic heterogeneity of this autosomal recessive disease. Our study emphasizes the usefulness of Next‐Generation Sequencing in unraveling the genetic cause of chronic kidney disease of unknown etiology, and raises the question of genetic modifiers involved in the variation of the phenotypes associated with autosomal recessive ITGA8 pathogenic variants. [ABSTRACT FROM AUTHOR]

Background/Aims: Healing of mesangioproliferative glomerulonephritis involves degradation of excess extracellular matrix, resolution of hypercellularity by apoptosis and phagocytosis of apoptotic cells. Integrin receptors participate in the regulation of phagocytosis. In mice deficient for alpha8 integrin (Itga8-/-) healing of glomerulonephritis is delayed. As Itga8 is abundant in mesangial cells (MC) which are non-professional phagocytes, we hypothesized that Itga8 facilitates phagocytosis of apoptotic cells and matrix components by MC. Methods: MC were isolated from wild type (WT) and Itga8-/- mice. Latex beads were coated with matrix components. Apoptosis was induced by cisplatin in macrophages and in DiI-stained MC. After coincubation of latex beads or apoptotic cells with MC, the phagocytosis rate was detected in WT and Itga8-/- MC via fluorescence microscopy and FACS analysis. Results: Itga8-/- MC showed reduced phagocytosis of matrix-coated beads and apoptotic cells compared to WT MC. Reduction of stress fibers was observed in Itga8-/- compared to WT MC. Inhibition of cytoskeletal reorganization by inhibition of Rac1 or ROCK during phagocytosis significantly decreased the rate of phagocytosis by WT MC but not by Itga8-/- MC. Conclusion: The expression of Itga8 facilitates phagocytosis in MC, likely mediated by Itga8-cytoskeleton interactions. An impairment of MC phagocytosis might thus contribute to a delayed glomerular regeneration in Itga8-/- mice.

Abstract Background Apoe-deficient (Apoe −/−) mice develop progressive atherosclerotic lesions with age but no severe renal pathology in the absence of additional challenges. We recently described accelerated atherosclerosis as well as marked renal injury in Apoe −/− mice deficient in the mesenchymal integrin chain Itga8 (Itga8 −/−). Here, we used this Apoe −/−, Itga8 −/− mouse model to investigate the sex differences in the development of atherosclerosis and concomitant renal injury. We hypothesized that aging female mice are protected from vascular and renal damage in this mouse model. Methods Apoe −/− mice were backcrossed with Itga8 −/− mice. Mice were kept on a normal diet. At the age of 12 months, the aortae and kidneys of male and female Apoe −/− Itga8 +/+ mice or Apoe −/− Itga8 −/− mice were studied. En face preparations of the aorta were stained with Sudan IV (lipid deposition) or von Kossa (calcification). In kidney tissue, immunostaining for collagen IV, CD3, F4/80, and PCNA and real-time PCR analyses for Il6, Vegfa, Col1a1 (collagen I), and Ssp1 (secreted phosphoprotein 1, synonym osteopontin) as well as ER stress markers were performed. Results When compared to male mice, Apoe −/− Itga8 +/+ female mice had a lower body weight, equal serum cholesterol levels, and lower triglyceride levels. However, female mice had increased aortic lipid deposition and more aortic calcifications than males. Male Apoe −/− mice with the additional deficiency of Itga8 developed increased serum urea, glomerulosclerosis, renal immune cell infiltration, and reduced glomerular cell proliferation. In females of the same genotype, these renal changes were less pronounced and were accompanied by lower expression of interleukin-6 and collagen I, while osteopontin expression was higher and markers of ER stress were not different. Conclusions In this model of atherosclerosis, the female sex is a risk factor to develop more severe atherosclerotic lesions, even though serum fat levels are higher in males. In contrast, female mice are protected from renal damage, which is accompanied by attenuated inflammation and matrix deposition. Thus, sex affects vascular and renal injury in a differential manner.

Background/Aims: Healing of mesangioproliferative glomerulonephritis involves degradation of excess extracellular matrix, resolution of hypercellularity by apoptosis and phagocytosis of apoptotic cells. Integrin receptors participate in the regulation of phagocytosis. In mice deficient for alpha8 integrin (Itga8-/-) healing of glomerulonephritis is delayed. As Itga8 is abundant in mesangial cells (MC) which are non-professional phagocytes, we hypothesized that Itga8 facilitates phagocytosis of apoptotic cells and matrix components by MC. Methods: MC were isolated from wild type (WT) and Itga8-/- mice. Latex beads were coated with matrix components. Apoptosis was induced by cisplatin in macrophages and in DiI-stained MC. After coincubation of latex beads or apoptotic cells with MC, the phagocytosis rate was detected in WT and Itga8-/- MC via fluorescence microscopy and FACS analysis. Results:Itga8-/- MC showed reduced phagocytosis of matrix-coated beads and apoptotic cells compared to WT MC. Reduction of stress fibers was observed in Itga8-/- compared to WT MC. Inhibition of cytoskeletal reorganization by inhibition of Rac1 or ROCK during phagocytosis significantly decreased the rate of phagocytosis by WT MC but not by Itga8-/- MC. Conclusion: The expression of Itga8 facilitates phagocytosis in MC, likely mediated by Itga8-cytoskeleton interactions. An impairment of MC phagocytosis might thus contribute to a delayed glomerular regeneration in Itga8-/- mice. [ABSTRACT FROM AUTHOR]

Background: Apoe-deficient (Apoe-/-) mice develop progressive atherosclerotic lesions with age but no severe renal pathology in the absence of additional challenges. We recently described accelerated atherosclerosis as well as marked renal injury in Apoe-/- mice deficient in the mesenchymal integrin chain Itga8 (Itga8-/-). Here, we used this Apoe-/-, Itga8-/- mouse model to investigate the sex differences in the development of atherosclerosis and concomitant renal injury. We hypothesized that aging female mice are protected from vascular and renal damage in this mouse model. Methods: Apoe-/- mice were backcrossed with Itga8-/- mice. Mice were kept on a normal diet. At the age of 12 months, the aortae and kidneys of male and female Apoe-/- Itga8+/+ mice or Apoe-/- Itga8-/- mice were studied. En face preparations of the aorta were stained with Sudan IV (lipid deposition) or von Kossa (calcification). In kidney tissue, immunostaining for collagen IV, CD3, F4/80, and PCNA and real-time PCR analyses for Il6, Vegfa, Col1a1 (collagen I), and Ssp1 (secreted phosphoprotein 1, synonym osteopontin) as well as ER stress markers were performed. Results: When compared to male mice, Apoe-/- Itga8+/+ female mice had a lower body weight, equal serum cholesterol levels, and lower triglyceride levels. However, female mice had increased aortic lipid deposition and more aortic calcifications than males. Male Apoe-/- mice with the additional deficiency of Itga8 developed increased serum urea, glomerulosclerosis, renal immune cell infiltration, and reduced glomerular cell proliferation. In females of the same genotype, these renal changes were less pronounced and were accompanied by lower expression of interleukin-6 and collagen I, while osteopontin expression was higher and markers of ER stress were not different. Conclusions: In this model of atherosclerosis, the female sex is a risk factor to develop more severe atherosclerotic lesions, even though serum fat levels are higher in males. In contrast, female mice are protected from renal damage, which is accompanied by attenuated inflammation and matrix deposition. Thus, sex affects vascular and renal injury in a differential manner. [ABSTRACT FROM AUTHOR]

Neuropathological and experimental evidence suggests that the cell-to-cell transfer of α-synuclein has an important role in the pathogenesis of Parkinson's disease (PD). However, the mechanism underlying this phenomenon is not fully understood. We undertook a small interfering RNA (siRNA), genome-wide screen to identify genes regulating the cell-to-cell transfer of α-synuclein. A genetically encoded reporter, GFP-2A-αSynuclein-RFP, suitable for separating donor and recipient cells, was transiently transfected into HEK cells stably overexpressing α-synuclein. We find that 38 genes regulate the transfer of α-synuclein-RFP, one of which is ITGA8, a candidate gene identified through a recent PD genome-wide association study (GWAS). Weighted gene co-expression network analysis (WGCNA) and weighted protein-protein network interaction analysis (WPPNIA) show that those hits cluster in networks that include known PD genes more frequently than expected by random chance. The findings expand our understanding of the mechanism of α-synuclein spread., Competing Interests: Declaration of interests B.T.H. has a family member who works at Novartis, and owns stock in Novartis; he serves on the scientific advisory board (SAB) of Dewpoint and owns stock; he serves on an SAB or is a consultant for Avrobio, AZTherapies, Biogen, Novartis, Cell Signaling, the U.S. Department of Justice, Takeda, Vigil, W20 Group, and Seer; and his laboratory is supported by sponsored research agreements with Abbvie and F-Prime and has research grants from the National Institutes of Health, Cure Alzheimer’s Fund, Tau Consortium, and the JPB Foundation., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Integrin alpha 8 (ITGA8) encodes the alpha 8 subunit of the integrin alpha8beta1 protein and has recently been suggested as a new candidate gene for Parkinson's disease, an age related neurodegenerative disease with unknown etiology. ITGA8 is a transmembrane protein involved in several cellular processes, such as cell adhesion, migration and cytoskeletal rearrangement., Objective: Screen a Swedish case control material for rs7077361, a genetic variant in ITGA8, in order to investigate its possible implication in Parkinson's disease in Sweden., Method: Rs7077361 was genotyped using TaqMan quantitative Real-time PCR and tested for association using appropriate statistical methods., Results: We have screened 502 Swedish Parkinson patients and 599 healthy control individuals for rs7077361 in ITGA8. This genetic variant was in Hardy Weinberg equilibrium in the Swedish population. Allele and genotype frequencies were highly similar between the patients and controls and statistical testing showed that this genetic maker did not associate with Parkinson's disease (p=0.67)., Conclusion: Our results do not support the hypothesis of ITGA8 as a candidate gene for Parkinson's disease in Sweden.

Congenital anomalies of the kidney and urinary tract (CAKUT) account for approximately 40% of children with ESRD in the United States. Hitherto, mutations in 23 genes have been described as causing autosomal dominant isolated CAKUT in humans. However, >90% of cases of isolated CAKUT still remain without a molecular diagnosis. Here, we hypothesized that genes mutated in recessive mouse models with the specific CAKUT phenotype of unilateral renal agenesis may also be mutated in humans with isolated CAKUT. We applied next-generation sequencing technology for targeted exon sequencing of 12 recessive murine candidate genes in 574 individuals with isolated CAKUT from 590 families. In 15 of 590 families, we identified recessive mutations in the genes FRAS1, FREM2, GRIP1, FREM1, ITGA8, and GREM1, all of which function in the interaction of the ureteric bud and the metanephric mesenchyme. We show that isolated CAKUT may be caused partially by mutations in recessive genes. Our results also indicate that biallelic missense mutations in the Fraser/MOTA/BNAR spectrum genes cause isolated CAKUT, whereas truncating mutations are found in the multiorgan form of Fraser syndrome. The newly identified recessive biallelic mutations in these six genes represent the molecular cause of isolated CAKUT in 2.5% of the 590 affected families in this study., (Copyright © 2014 by the American Society of Nephrology.)