PPP3R1 Promotes MSCs Senescence by Inducing Plasma Membrane Depolarization and Increasing Ca2+ Influx

Aging of mesenchymal stem cells(MSCs) has been widely reported to be strongly associated with aging-related diseases, including osteoporosis (OP). In particular, the beneficial functions of mesenchymal stem cells decline with age, limiting their therapeutic efficacy in age-related bone loss diseases. Therefore, how to improve mesenchymal stem cell aging to treat age-related bone loss is the current research focus. However, the underlying mechanism remains unclear. In this study, protein phosphatase 3, regulatory subunit B, alpha isoform, calcineurin B, type I (PPP3R1) was found to accelerate the senescence of mesenchymal stem cells, resulting in reduced osteogenic differentiation and enhanced adipogenic differentiation in vitro. Mechanistically, PPP3R1 induces changes in membrane potential to promote cellular senescence by polarizing to depolarizing, increasing Ca²⁺ influx and activating downstream NFAT/ATF3/p53 signaling. In conclusion, the results identify a novel pathway of mesenchymal stem cell aging that may lead to novel therapeutic approaches for age-related bone loss.

MiR-548a-3p Promotes Keratinocyte Proliferation Targeting PPP3R1 after Being Induced by IL-22

Psoriasis is an immune-mediated chronic skin disorder where T cells play a main role, and numerous inflammatory cytokines are implicated in its pathogenesis by initiating keratinocyte proliferation. Interleukin-22 (IL-22), an IL-10 family cytokines, is critical in the pathogenesis and development of psoriasis. To determine the target of microRNA (miR) -548a-3p and investigate its role in keratinocyte proliferation after treating human keratinocytes (HaCaT) with IL-22, we used quantitative reverse transcriptase PCR to measure the expression of miR-548a-3p in both HaCaT cells stimulated with IL-22 and psoriatic lesions, and then detected the biological function of miR-548a-3p in HaCaT cells by performing Counting Kit-8 (CCK-8) assays. Luciferase reporter assay was conducted to determine the target gene of miR-548a-3p. Immunohistochemistry and Western blot were performed to verify the target gene. Results showed that miR-548a-3p was significantly upregulated both in HaCaT cells treated with IL-22 and psoriatic lesions. The over expression of miR-548a-3p could promote the proliferation of HaCaT cells. Luciferase was mutated in the 3'UTR of PPP3R1, a gene coding Calcineurin. Immunohistochemistry and Western blot demonstrated that the expression of PPP3R1 decreased respectively in psoriatic lesions and HaCaT cells. In conclusion, the expression of miR-548a-3p is upregulated in IL-22 mediated keratinocyte proliferative disorder like psoriasis. The impact of miR-548a-3p on keratinocyte proliferation may be implemented by targeting PPP3R1 and T regulatory cells may be involved in the pathogenesis of psoriasis.

Association of CnB 5I/5D promoter gene polymorphism and serum calcineurin levels in early onset of coronary artery disease of south Indian cohort

Calcineurin, a serine/threonine phosphatase is a calcium dependent protein which on activation triggers transcriptional up regulation of inflammatory genes associated with inflammation in the arteries and progressive formation of plaques in CAD. The present investigation is aimed to study the possible association of Calcineurin encoding gene PPP3R1 (CnB 5I/5D) polymorphism in correlation with serum levels of calcineurin in coronary artery disease (CAD). A total of 300 angiographically documented CAD patients and 300 age, gender ethnicity matched healthy controls were recruited for the study. Serum Calcineurin levels were estimated by enzyme-linked immunosorbent assay (ELISA) and genotypes were determined based on PCR-RFLP. The CnB 5I/5D variation was found to be significantly associated with CAD (p<0.03), correlated to elevated serum calcineurin levels encoded by (<0.01) 5I/5D allele authenticated by Insilco analysis. Multiple logistic regression analysis also confirmed these findings [adjusted OR for DD genotype was 3.19 (95% CI 1.40-7.24) and p=0.001]. The results suggest that 5-base pair deletion results in increased serum calcineurin levels and may trigger up regulation of calcineurin which mediates vascular inflammation and atherosclerosis in CAD.

NFATC1 genotypes affect acute rejection and long-term graft function in cyclosporine-treated renal transplant recipients

AIM

To investigate the effects of SNPs in the cyclophilin A/calcineurin/nuclear factor of activated T-cells (NFATs) pathway genes (PPIA, PPP3CB, PPP3R1, NFATC1 and NFATC2) on cyclosporine (CsA) efficacy in renal transplant recipients.

MATERIALS & METHODS

Seventy-six tag SNPs were detected in 155 CsA-treated renal recipients with at least a 5-year follow-up. The associations of SNPs with acute rejection, nephrotoxicity, pneumonia and estimated glomerular filtration rate post transplant were explored.

RESULTS

NFATC1 rs3894049 GC was a risk factor for acute rejection compared with CC carriers (p = 0.0005). NFATC1 rs2280055 TT carriers had a more stable estimated glomerular filtration rate level than CC (p = 0.0004).

CONCLUSION

Detecting NFATC1 polymorphisms could help predict CsA efficacy in renal transplant patients.

Placenta-specific miRNA (miR-512-3p) targets PPP3R1 encoding the calcineurin B regulatory subunit in BeWo cells

AIM

The microRNAs (miRNAs) derived from the chromosome 19 miRNA cluster (C19MC) are exclusively expressed in the human placenta, but the origin and functions of C19MC miRNAs are not fully understood. The purpose of this study was to elucidate which cells express C19MC miRNAs in chorionic villi and identify their miRNA targets.

METHODS

A combination of laser microdissection (LMD) and real-time polymerase chain reaction (PCR) to examine the localization of five C19MC miRNAs (i.e. miR-512-3p, miR-518b, miR-520a, miR-524 and miR-1323) in the human placenta was performed. Furthermore, to identify miR-512-3p-target genes, we analyzed gene expression profiles of the trophoblast cell line BeWo using a DNA microarray. Predicted target genes were validated by real-time PCR, western blotting, and 3'-untranslated region reporter assay.

RESULTS

By LMD and subsequent PCR analysis, five C19MC miRNAs examined in this study were predominantly expressed in villous trophoblast cells; little expression, if any, was observed in villous stroma cells or fetal endothelial cells. Microarray data showed that 334 genes were downregulated in BeWo cells treated with Pre-miR-512-3p (mature miR-512-3p mimic). We found six candidate target genes of miR-512-3p using DNA microarray data and target prediction software. Furthermore, we revealed that protein phosphatase 3, regulatory subunit B, alpha (PPP3R1), one of the six genes, was a miR-512-3p target using an in vitro experimental validation system.

CONCLUSION

These data suggest that miR-512-3p participates in human trophoblast function[s] by targeting PPP3R1, encoding a regulatory subunit of calcineurin.

Variants in PPP3R1 and MAPT are associated with more rapid functional decline in Alzheimer's disease: the Cache County Dementia Progression Study

BACKGROUND

Single-nucleotide polymorphisms (SNPs) located in the gene encoding the regulatory subunit of the protein phosphatase 2B (PPP3R1, rs1868402) and the microtubule-associated protein tau (MAPT, rs3785883) gene were recently associated with higher cerebrospinal fluid (CSF) tau levels in samples from the Knight Alzheimer's Disease Research Center at Washington University (WU) and Alzheimer's Disease Neuroimaging Initiative (ADNI). In these same samples, these SNPs were also associated with faster functional decline, or progression of Alzheimer's disease (AD) as measured by the Clinical Dementia Rating sum of boxes scores (CDR-sb). We attempted to validate the latter association in an independent, population-based sample of incident AD cases from the Cache County Dementia Progression Study (DPS).

METHODS

All 92 AD cases from the DPS with a global CDR-sb ≤1 (mild) at initial clinical assessment who were later assessed on CDR-sb data on at least two other time points were genotyped at the two SNPs of interest (rs1868402 and rs3785883). We used linear mixed models to estimate associations between these SNPs and CDR-sb trajectory. All analyses were performed using Proc Mixed in SAS.

RESULTS

Although we observed no association between rs3785883 or rs1868402 alone and change in CDR-sb (P > .10), there was a significant association between a combined genotype model and change in CDR-sb: carriers of the high-risk genotypes at both loci progressed >2.9 times faster than noncarriers (P = .015). When data from DPS were combined with previously published data from WU and ADNI, change in CDR-sb was 30% faster for each copy of the high-risk allele at rs3785883 (P = .0082) and carriers of both high-risk genotypes at both loci progressed 6 times faster (P < .0001) than all others combined.

CONCLUSIONS

We replicate a previous report by Cruchaga et al that specific variations in rs3785883 and rs1868402 are associated with accelerated progression of AD. Further characterization of this association will provide a better understanding of how genetic factors influence the rate of progression of AD and could provide novel insights into preventative and therapeutic strategies.