Abstract. CCN2 and CCN3 belong to the CCN family of proteins, which show a high level of structural similarity. Previous studies have shown that CCN2 mediates the ability of transforming growth factor (TGF)-β to stimulate collagen synthesis, leading to keloid formation. CCN2 and CCN3 are opposing factors in regulating the promoter activity and secretion of this extracellular matrix (ECM) protein. Thus, we hypothesize that CCN3 possesses an anti-scarring effect. However, the exact mechanism of CCN3 in this anti-scarring effect remains unclear. The aim of this study was to investigate the mechanism of CCN3 in reducing scar formation. Palatal fibroblasts were obtained from the explants of the oral palatal mucosa of 8-week-old male Sprague-Dawley rats. CCN3 overexpression vector was constructed and then transfected into cells. The inhibitory effects of CCN3 on cell growth were detected via the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was measured using an Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) apoptosis detection kit and flow cytometry. The expression levels of collagen I, collagen III and α-smooth muscle actin (α-SMA) were determined by western blot analysis and RT-PCR. Following treatment with TGF-β1, we detected the expression of CCN3 and Smad1 in the fibroblasts. CCN3 significantly inhibited the growth and induction of apoptosis of fibroblasts. The expression of collagen I, collagen III and α-SMA was lower in the CCN3-transfected group as compared to the control and vector groups. TGF-β1 stimulation efficiently suppressed the expression of CCN3 at the mRNA and protein levels, and CCN3 was required for TGF-β1-induced Smad1 phosphorylation. Results of this study demonstrated that CCN3 is involved in the proliferation and apoptosis of fibroblasts and the synthesis of ECM proteins. Therefore, CCN3 may play an important role in the development of scar tissue, and may represent a novel therapeutic target for reducing scar formation.

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Familial renal glucosuria (FRG) is a rare genetic condition featured by isolated glucosuria without hyperglycemia or other kidney diseases. It is caused by pathogenic mutations of the SGLT2 (Sodium-Glucose Cotransporter 2) gene, whose protein product is responsible for reabsorbing the majority of glucose in the early proximal convoluted tubule. Hitherto, quite an array of variants of SGLT2 have been identified in patients of FRG. In this study, we performed whole exome sequencing on three Chinese pediatric patients with FRG and uncovered three compound heterozygous variants of SGLT2: c.1333C > T (p.Q445X) and c.1130–5 C > G; c.1438G > T (p.V480F) and c.346G > A (p.V116M); c.1175C > G (p.S392C) and c.1333C > T (p.Q445X). Among the total of five variants, c.1333C > T (p.Q445X), c.1438G > T (p.V480F) and c.1175C > G (p.S392C) represented novel variants that had not been reported in any genetic databases. All five variants had extremely low allele frequencies and the amino acids loci affected by missense variants were highly conserved in vertebrate species. Bioinformatic tools predicted that all five variants might disrupt the function of SGLT2, which were likely to be causal for FRG in these patients. Our findings expand the variant spectrum of SGLT2 associated with FRG and provide novel insights into mechanism of action of this transporter, which will aid in the development of novel SGLT2 inhibitors for treatment of type 2 diabetes and cardiovascular diseases.