The involvement of let-7 in hCG-induced progesterone synthesis via regulating p27Kip1 and p21Cip1 expression

Progesterone is essential in females to maintain a regular menstrual cycle and pregnancy. The luteinizing hormone (LH) surge induces the luteinization of granulosa cells and thecal cells to form the corpus luteum, which is responsible for progesterone synthesis. However, the specific mechanism of how hCG, the analog of LH, regulates progesterone synthesis has yet to be fully discovered. In this study, we found that progesterone level was increased in adult wild-type pregnant mice 2 and 7 days post-coitum, along with a decrease in let-7 expression compared with the estrus stage. Besides, the let-7 expression was negatively correlated with progesterone level in post-delivery day 23 wild-type female mice after being injected with PMSG and hCG. Then, using let-7 transgenic mice and a human granulosa cell line, we found that overexpression of let-7 antagonized progesterone level via targeting p27^Kip1 and p21^Cip1 and steroidogenic acute regulatory protein (StAR) expression, which is a rate-limiting enzyme in progesterone synthesis. Furthermore, hCG suppressed let-7 expression by stimulating the MAPK pathway. This study elucidated the role of microRNA let-7 in regulating hCG-induced progesterone production and provided new insights into its role in clinical application.

A novel CDK-independent function of p27Kip1 in preciliary vesicle trafficking during ciliogenesis

p27^Kip1, a member of the Cip/Kip family of cyclin-dependent kinase (CDK) inhibitors, is now known as a multifunctional protein that plays crucial roles in cell architecture and migration by regulating rearrangements of the actin cytoskeleton and microtubules. The intracellular level of p27^Kip1 is increased by anti-proliferative stimuli, such as mitogen deprivation and contact inhibition, which also induce formation of primary cilia, microtubule-based membranous organelles that protrude from the cell surface. However, it remains unknown whether p27^Kip1 is associated with ciliogenesis. Here, we have generated p27^Kip1-knockout hTERT-immortalized human retinal pigment epithelial cells, and found that ciliogenesis is almost completely disrupted in p27^Kip1-knockout cells. The defect of ciliogenesis is rescued by the exogenous expression of wild-type p27^Kip1 and, surprisingly, its 86-140 amino acid region, which is neither responsible for CDK inhibition nor remodeling of the actin cytoskeleton and microtubules. Moreover, transmission electron microscopy and immunofluorescence analyses reveal that p27^Kip1 abrogation impairs one of the earliest events of ciliogenesis, docking of the Ehd1-associated preciliary vesicles to the distal appendages of the basal body. Our findings identify a novel CDK-independent function of p27^Kip1 in primary cilia formation.

Hydroxychloroquine suppresses lung tumorigenesis via inducing FoxO3a nuclear translocation through STAT3 inactivation

BACKGROUND

Hydroxychloroquine exhibits synergistic anticancer properties as an adjuvant. However, the role and molecular mechanisms underlying of HCQ as monotherapy for lung adenocarcinoma (LUAD) have yet to be elucidated.

METHODS

We assessed the antitumor effects of HCQ in LUAD cells through a series of in vitro and in vivo assays. GEO database and R packages were used to predict molecular mechanisms of HCQ in the treatment of lung adenocarcinoma, followed by verification of gene expression and subcellular localization via immunoblotting, immunofluorescent and immunohistochemistry assays.

RESULTS

We showed the phenotypic effects that HCQ inhibited cell growth, induced apoptosis and cell cycle arrest at G1/S transition in A549 and PC-9 cells, which was associated with inhibition of CDK2, CDK4, CyclinD1 and CyclinE, but up-regulation of p21 and p27^Kip1. Bioinformatic analysis predicted that 63 targets related to HCQ and LUAD were mainly enriched in JAK-STAT and FoxO pathways. Then, we observed that HCQ decreased the phosphorylation of STAT3, but increased the expression of FoxO3a and its accumulation in the nucleus. The specific STAT3 inhibitor cryptotanshinon augmented the HCQ-induced upregulation and nuclear translocation of FoxO3a. In addition, HCQ increased the expression of p27^Kip1, which was impaired by FoxO3a blockade with siRNA. Finally, ablation of p27^Kip1 expression abrogated the cytotoxicity of HCQ. More importantly, similar results were further confirmed in vivo.

CONCLUSIONS

Taken together, this study suggests that STAT3/FoxO3a/p27^Kip1 signaling pathway is involved in the anticancer effects of HCQ, and provides preliminary evidence for therapeutic prospects of HCQ alone in LUAD.

Cks1 regulates human hepatocellular carcinoma cell progression through osteopontin expression

Precise cell cycle regulation is critical to prevent aberrant cell proliferation and cancer progression. Cks1 was reported to be an essential accessory factor for SCF^Skp2, the ubiquitin ligase that targets p27^Kip1 for proteasomal degradation; these actions drive mammalian cell transition from G1 to S phase. In this study, we investigated the role played by Cks1 in the growth and progression of human hepatocellular carcinoma (HCC) cells. Silencing Cks1 expression abrogated osteopontin (OPN) expression in a p27^Kip1-dependent manner in Huh7 HCC cells. OPN increased the proliferation, migration and invasion of Huh7 cells. Pharmacological inhibitor studies demonstrated that ERK1/2 signaling is responsible mainly for Cks1-mediated OPN expression. Cks1 appears to regulate ERK1/2 signaling through the expression of dual-specificity phosphatase 16 (DUSP16) because both Cks1 knockdown, which leads to DUSP16 upregulation, and DUSP16 overexpression decreased ERK1/2 phosphorylation and the resulting OPN expression. The same is true for the Cks1-mediated increases in p27^Kip1, suggesting that Cks1 regulates OPN expression through activating ERK1/2 signaling either by suppressing DUSP16 expression or by a p27^Kip1-dependent mechanism. Cks1 and OPN expression levels were significantly higher, but DUSP16 expression levels were significantly lower in HCC tissues than in normal liver tissues. Both Cks1 and OPN expression were negatively correlated with DUSP16 expression, whereas Cks1 expression was positively correlated with OPN expression. Moreover, combined panels for the expression levels of Cks1, DUSP16 and OPN showed significant prognostic power for the risk assessment of HCC patient overall survival. In conclusion, our data propose a novel function for Cks1 as a tumor promoter through the expression of the strongly oncogenic protein OPN in HCC.

p27Kip1 regulates the microtubule bundling activity of PRC1

Cytokinesis begins in anaphase with the formation of the central spindle. PRC1 is a microtubule associated protein that plays an essential role in central spindle formation by crosslinking antiparallel microtubules. We have identified PRC1 as a novel binding partner for p27^Kip1 (p27). p27 is a cyclin-CDK inhibitor that causes cell cycle arrest in G1. However, p27 has also been involved in the regulation of G2/M progression and cytokinesis, as well as of other cellular processes, including actin and microtubule cytoskeleton dynamics. We found that p27 interferes with the ability of PRC1 to bind to microtubules, without affecting PRC1 dimerization or its capacity to interact with other partners such as KIF4. In this way, p27 inhibited microtubule bundling by PRC1 in vitro and prevented the extensive microtubule bundling phenotype caused by PRC1 overexpression in cells in culture. Finally, co-expression of p27 or a p27 mutant that does not bind cyclin-CDKs inhibited multinucleation induced by PRC1 overexpression. Together, our results suggest that p27 may participate in the regulation of mitotic progression in a CDK-independent manner by modulating PRC1 activity.

Gp78 involvement in cellular proliferation: Can act as a promising modulator for cell cycle regulatory proteins?

In cells, protein synthesis and degradation are normal processes, which are tightly regulated by various cellular metabolic pathways. Cellular protein quality control (PQC) mechanisms always present a continuous and rigorous check over all intracellular proteins before they can participate in various cellular physiological processes with the help of PQC pathways like autophagy and ubiquitin proteasome system (UPS). The UPS employs few selective E3 ubiquitin ligases for the intracellular degradation of cyclin-dependent kinase inhibitor 1B (p27^Kip1 ) that tightly controls cell cycle progression. But, the complex mechanistic interactions and the interplay between E3 ubiquitin ligases involved in the functional regulation as well as expression of p27 are not well known. Here, we demonstrate that cell surface glycoprotein Gp78, a putative E3 ubiquitin ligase, is involved in the stabilization of intracellular steady-state levels of p27. Transient overexpression of Gp78 increases the accumulation of p27 in cells in the form of massive inclusions like structures, which could be due to its cumulative increased stability in cells. We have also monitored how under stress condition, E3 ubiquitin ligase Gp78 regulates endogenous levels of p27 in cells. ER stress treatment generates a marginal increase in Gp78 endogenous levels, and this elevation effect was prominent for intracellular accumulation of p27 in cells. Taken together, our current findings suggest a valuable multifactorial regulatory mechanism and linkage of p27 with UPS pathway.

Mapping Interactions between p27 and RhoA that Stimulate Cell Migration

p27 mediates cell cycle arrest by binding to and inhibiting cyclin-dependent kinase/cyclin complexes, but p27 can also contribute to pro-oncogenic signaling upon mislocalization to the cytoplasm. Cytoplasmic p27 stimulates cell migration by associating with RhoA and interfering with the exchange of GDP from RhoA stimulated by guanine nucleotide exchange factors. We used biophysical methods to show that the N-terminus of p27 directly interacts with RhoA in vitro. The affinity of p27 for RhoA is low, with an equilibrium dissociation constant of hundreds of micromolar; however, at high concentrations, p27 interfered with guanine nucleotide exchange factor-mediated nucleotide exchange from RhoA. We also show that promotion of cell migration in scratch wound cell healing assays requires full-length p27 despite the C-terminus being dispensable for the direct interaction between p27 and RhoA in vitro. These results suggest that there may be an unidentified factor(s) that associates with the C-terminus of p27 to enhance its interactions with RhoA and promote cell migration.

Upregulation of miR-221 and -222 in response to increased extracellular signal-regulated kinases 1/2 activity exacerbates neointimal hyperplasia in diabetes mellitus

BACKGROUND AND AIMS

Diabetes is associated with accelerated arterial intimal thickening that contributes to the increased cardiovascular disease seen in this population. In healthy arteries, intimal thickening is inhibited by elevated levels of the cyclin-dependent kinase inhibitor, p27^Kip1, and intimal thickening is promoted by activation of the mammalian Target of Rapamycin to promote degradation of p27^Kip1 protein. Recently, we reported that two microRNAs, miR-221 and -222, which promote intimal thickening via down-regulation of mRNA encoding p27^Kip1, are elevated in the arteries of diabetic patients. To determine if these miRNAs are critical to the increased intimal thickening under diabetic conditions, we examined the regulation of p27^Kip1in a mouse model of diabetes.

METHODS

Comparisons of p27^Kip1 signaling in NONcNZO10 mice fed a diabetogenic versus control diet were performed using immunochemistry and real-time PCR.

RESULTS

Vascular smooth muscle cells and arteries of diabetic mice exhibited decreased levels of p27^Kip1 that derived from destabilization of p27^Kip1 mRNA in an extracellular signal response kinase-1/2 (ERK-1/2) dependent manner. The activity of ERK-1/2 is increased in the arteries of diabetic mice and promotes an increase in miR-221 and -222. Inhibition of miR-221 and -222 restores normal levels of p27^Kip1 mRNA and protein in the arteries of diabetic mice and reduces intimal thickening following wire injury.

CONCLUSIONS

These data suggest diabetes is accompanied by increases in arterial miR-221 and -222 expression that promotes intimal thickening. Inhibition of the increased miR-221 and -222 may be efficacious in the prevention of the cardiovascular complications of diabetes.

Lysine-specific demethylase-1 (LSD1) is compartmentalized at nuclear chromocenters in early post-mitotic cells of the olfactory sensory neuronal lineage

Mammalian olfaction depends on the development of specialized olfactory sensory neurons (OSNs) that each express one odorant receptor (OR) protein from a large family of OR genes encoded in the genome. The lysine-specific demethylase-1 (LSD1) protein removes activating H3K4 or silencing H3K9 methylation marks at gene promoters and is required for proper OR regulation. We show that LSD1 protein exhibits variable organization within nuclei of developing OSNs, and tends to consolidate into a single dominant compartment at the edges of chromocenters within nuclei of early post-mitotic cells of the mouse olfactory epithelium (MOE). Using an immortalized cell line derived from developing olfactory placode, we show that consolidation of LSD1 appears to be cell-cycle regulated, with a peak occurrence in early G1. LSD1 co-compartmentalizes with CoREST, a protein known to collaborate with LSD1 to carry out a variety of chromatin-modifying functions. We show that LSD1 compartments co-localize with 1-3 OR loci at the exclusion of most OR genes, and commonly associate with Lhx2, a transcription factor involved in OR regulation. Together, our data suggests that LSD1 is sequestered into a distinct nuclear space that might restrict a histone-modifying function to a narrow developmental time window and/or range of OR gene targets.

New Insights Into the Mechanism of COP9 Signalosome-Cullin-RING Ubiquitin-Ligase Pathway Deregulation in Urological Cancers

Urological cancers are a very common type of cancer worldwide and have alarming high incidence and mortality rates, especially in kidney cancers, illustrate the urgent need for new therapeutic targets. Recent publications point to a deregulated COP9 signalosome (CSN)-cullin-RING ubiquitin-ligase (CRL) pathway which is here considered and investigated as potential target in urological cancers with strong focus on renal cell carcinomas (RCC). The CSN forms supercomplexes with CRLs in order to preserve protein homeostasis and was found deregulated in several cancer types. Examination of selected CSN-CRL pathway components in RCC patient samples and four RCC cell lines revealed an interesting deregulated p27(Kip1)-Skp2-CAND1 axis and two p27(Kip1) point mutations in 786-O cells; p27(Kip1)V109G and p27(Kip1)I119T. The p27(Kip1) mutants were detected in patients with RCC and appear to be responsible for an accelerated growth rate in 786-O cells. The occurrence of p27(Kip1)V109G and p27(Kip1)I119T in RCC makes the CSN-CRL pathway an attractive therapeutic target.

Salivary protein histatin 3 regulates cell proliferation by enhancing p27(Kip1) and heat shock cognate protein 70 ubiquitination

Histatins are salivary proteins with antimicrobial activities. We previously reported that histatin 3 binds to heat shock cognate protein 70 (HSC70), which is constitutively expressed, and induces DNA synthesis stimulation and promotes human gingival fibroblast (HGF) survival. However, the underlying mechanisms of histatin 3 remain largely unknown. Here, we found that the KRHH sequence of histatin 3 at the amino acid positions 5-8 was essential for enhancing p27(Kip1) (a cyclin-dependent kinase inhibitor) binding to HSC70 that occurred in a dose-dependent manner; histatin 3 enhanced the binding between p27(Kip1) and HSC70 during the G1/S transition of HGFs as opposed to histatin 3-M(5-8) (substitution of KRHH for EEDD in histatin 3). Histatin 3, but not histatin 3-M(5-8), stimulated DNA synthesis and promoted HGF survival. Histatin 3 dose-dependently enhanced both p27(Kip1) and HSC70 ubiquitination, whereas histatin 3-M(5-8) did not. These findings provide further evidence that histatin 3 may be involved in the regulation of cell proliferation, particularly during G1/S transition, via the ubiquitin-proteasome system of p27(Kip1) and HSC70.

Silencing of DYRK2 increases cell proliferation but reverses CAM-DR in Non-Hodgkin's Lymphoma

DYRK2, a dual-specificity tyrosine-(Y)-phosphorylation regulated kinase gene, is involved in regulating many processes such as cell proliferation, cell differentiation and cytokinesis. DYRK2 also plays an important role in many cancers, such as breast cancer, non-small cell lung cancer and esophageal adenocarcinomas. In this study, we found that DYRK2 is associated with the proliferation of Non-Hodgkin's lymphoma (NHL) and cell adhesion mediated drug resistance (CAM-DR). Clinically, the mRNA and protein expression levels of DYRK2 are decreased in NHL tissues compared with reactive lymphoid hyperplasia tissues. Immunohistochemical analysis revealed that low expression of DYRK2 is associated with poor prognosis of NHL patients. Interestingly, knockdown of DYRK2 can promote cell proliferation via modulating cell cycle progression. Finally, we demonstrated that DYRK2 plays an important role in CAM-DR by regulating p27(Kip1) expression. Importantly, DYRK2 knockdown reverses CAM-DR in NHL. Our research suggested that DYRK2 may be a novel therapeutic target for NHL.

p27(Kip1) and p21(Cip1)-independent proliferative inhibition of vascular smooth muscle cells cultured in type-I collagen matrix honeycombs

The proliferation of vascular smooth muscle cells (SMCs) contributes to atherosclerotic plaque formation and restenosis. Cyclin-dependent kinase inhibitors, such as p27(Kip1) and p21(Cip1), are known to play significant roles in the control of the aberrant proliferation of SMCs. Primary cultured SMCs stop proliferating immediately when cultured in three-dimensional matrices of type-I collagen "honeycombs" structures. To clarify whether p27(Kip1) and p21(Cip1) are involved in the proliferative inhibition of SMCs cultured in honeycombs, the characteristics of SMCs derived from the aorta of both wild-type mice (p27[+/+] SMCs) and p27(Kip1) knockout mice (p27[-/-] SMCs) were investigated. Although the growth of p27(-/-) SMCs cultured on plates was faster than that of p27(+/+) SMCs, the number of both p27(+/+) and p27(-/-) SMCs did not change when they were cultured in honeycombs. p21(Cip1) expression was decreased but maintained in p27(-/-) SMCs cultured on plates and in honeycombs. Knockdown of p21(Cip1) in p27(-/-) SMCs promoted proliferation on plates. On the contrary, p21(Cip1) knockdown had no effect on the proliferation of p27(-/-) SMCs cultured in honeycombs. In conclusion, p27(Kip1) and p21(Cip1) are insufficient for the proliferative inhibition of SMCs cultured in honeycombs.

p27(Kip1) signaling: Transcriptional and post-translational regulation

p27(Kip1) is an inhibitor of a broad spectrum of cyclin-dependent kinases (CDKs), and the loss of a single p27(Kip1) allele is thereby sufficient to increase tumor incidence via CDK-mediated cell cycle entry. As such, down-regulation of p27(Kip1) protein levels, in particular nuclear expressed p27(Kip1), is implicated in both disease progression and poor prognosis in a variety of cancers. p27(Kip1) expression is positively regulated by the transcription factor MENIN, and inhibited by oncogenic transcription factors MYC and PIM. However, regulation of p27(Kip1) protein expression and function is predominantly through post-translational modifications that alter both the cellular localization and the extent of E3 ubiquitin ligase-mediated degradation. Phosphorylation of p27(Kip1) at Thr(187) and Ser(10) is a prerequisite for its degradation via the E3 ubiquitin ligases SKP2 (nuclear) and KPC (cytoplasmic), respectively. Additionally, Ser(10) phosphorylated p27(Kip1) is predominantly localized in the cytoplasm due to the nuclear export protein CRM1. Another E3 ubiquitin ligase, PIRH2, degrades p27(Kip1) in both the cytoplasm and nucleus independent of phosphorylation state. As such, inhibition of cell cycle entry and progression in a variety of cancers may be achieved with therapies designed to correct p27(Kip1) localization and/or block its degradation.

UCH-L1 induces podocyte hypertrophy in membranous nephropathy by protein accumulation

Podocytes are terminally differentiated cells of the glomerular filtration barrier that react with hypertrophy in the course of injury such as in membranous nephropathy (MGN). The neuronal deubiquitinase ubiquitin C-terminal hydrolase L1 (UCH-L1) is expressed and activated in podocytes of human and rodent MGN. UCH-L1 regulates the mono-ubiquitin pool and induces accumulation of poly-ubiquitinated proteins in affected podocytes. Here, we investigated the role of UCH-L1 in podocyte hypertrophy and in the homeostasis of the hypertrophy associated "model protein" p27(Kip1). A better understanding of the basic mechanisms leading to podocyte hypertrophy is crucial for the development of specific therapies in MGN. In human and rat MGN, hypertrophic podocytes exhibited a simultaneous up-regulation of UCH-L1 and of cytoplasmic p27(Kip1) content. Functionally, inhibition of UCH-L1 activity and knockdown or inhibition of UCH-L1 attenuated podocyte hypertrophy by decreasing the total protein content in isolated glomeruli and in cultured podocytes. In contrast, UCH-L1 levels and activity increased podocyte hypertrophy and total protein content in culture, specifically of cytoplasmic p27(Kip1). UCH-L1 enhanced cytoplasmic p27(Kip1) levels by nuclear export and decreased poly-ubiquitination and proteasomal degradation of p27(Kip1). In parallel, UCH-L1 increased podocyte turnover, migration and cytoskeletal rearrangement, which are associated with known oncogenic functions of cytoplasmic p27(Kip1) in cancer. We propose that UCH-L1 induces podocyte hypertrophy in MGN by increasing the total protein content through altered degradation and accumulation of proteins such as p27(Kip1) in the cytoplasm of podocytes. Modification of both UCH-L1 activity and levels could be a new therapeutic avenue to podocyte hypertrophy in MGN.

Knockdown of CRM1 inhibits the nuclear export of p27(Kip1) phosphorylated at serine 10 and plays a role in the pathogenesis of epithelial ovarian cancer

In a previous study, the nuclear export protein chromosomal region maintenance (CRM1) was correlated with p27(Kip1) in glioma. The aims of the present study were to investigate the expression of CRM1 and pSer10p27 and their functional roles in epithelial ovarian cancer (EOC) tissues. Using immunohistochemical analysis, CRM1 and pSer10p27 expression levels were shown to be associated with histologic stage and grade (P<0.05). High CRM1 and pSer10p27 expression levels were prognostic indicators of overall survival (P<0.05). Knockdown of CRM1 and pSer10p27 expression arrested cell cycle progression and inhibited the proliferation of SKOV3 cells both in vitro and in vivo. These data support the idea that pSer10p27 and CRM1 play cooperative roles in EOC.

p27(Kip1) inhibits tissue factor expression

BACKGROUND

The cyclin-dependent kinase inhibitor (CDKI) p27(Kip1) regulates cell proliferation and thus inhibits atherosclerosis and vascular remodeling. Expression of tissue factor (TF), the key initator of the coagulation cascade, is associated with atherosclerosis. Yet, it has not been studied whether p27(Kip1) influences the expression of TF.

METHODS AND RESULTS

p27(Kip1) overexpression in human aortic endothelial cells was achieved by adenoviral transfection. Cells were rendered quiescent for 24h in 0.5% fetal-calf serum. After stimulation with TNF-α (5 ng/ml), TF protein expression and activity was significantly reduced (n=4; P<0.001) in cells transfected with p27(Kip1). In line with this, p27(Kip1) overexpression reduced cytokine-induced TF mRNA expression (n=4; P<0.01) and TF promotor activity (n=4; P<0.05). In contrast, activation of the MAP kinases p38, ERK and JNK was not affected by p27(Kip1) overexpression.

CONCLUSION

This in vitro study suggests that p27(Kip1) inhibits TF expression at the transcriptional level. These data indicate an interaction between p27(Kip1) and TF in important pathological alterations such as atherosclerosis and vascular remodeling.

The negative cell cycle regulators, p27(Kip1), p18(Ink4c), and GSK-3, play critical role in maintaining quiescence of adult human pancreatic β-cells and restrict their ability to proliferate

Adult human pancreatic β-cells are primarily quiescent (G0) yet the mechanisms controlling their quiescence are poorly understood. Here, we demonstrate, by immunofluorescence and confocal microscopy, abundant levels of the critical negative cell cycle regulators, p27(Kip1) and p18(Ink4c), 2 key members of cyclin-dependent kinase (CDK) inhibitor family, and glycogen synthase kinase-3 (GSK-3), a serine-threonine protein kinase, in islet β-cells of adult human pancreatic tissue. Our data show that p27(Kip1) localizes primarily in β-cell nuclei, whereas, p18(Ink4c) is mostly present in β-cell cytosol. Additionally, p-p27(S10), a phosphorylated form of p27(Kip1), which was shown to interact with and to sequester cyclinD-CDK4/6 in the cytoplasm, is present in substantial amounts in β-cell cytosol. Our immunofluorescence analysis displays similar distribution pattern of p27(Kip1), p-p27(S10), p18(Ink4c) and GSK-3 in islet β-cells of adult mouse pancreatic tissue. We demonstrate marked interaction of p27(Kip1) with cyclin D3, an abundant D-type cyclin in adult human islets, and vice versa as well as with its cognate kinase partners, CDK4 and CDK6. Likewise, we show marked interaction of p18(Ink4c) with CDK4. The data collectively suggest that inhibition of CDK function by p27(Kip1) and p18(Ink4c) contributes to human β-cell quiescence. Consistent with this, we have found by BrdU incorporation assay that combined treatments of small molecule GSK-3 inhibitor and mitogen/s lead to elevated proliferation of human β-cells, which is caused partly due to p27(Kip1) downregulation. The results altogether suggest that ex vivo expansion of human β-cells is achievable via increased proliferation for β-cell replacement therapy in diabetes.