Organoid-derived human retinal progenitor cells promote early dedifferentiation of Müller glia in Royal College of Surgeons rats

AIM:To explore whether the subretinal transplantation of retinal progenitor cells from human embryonic stem cell-derived retinal organoid(h ERO-RPCs)could promote Müller glia dedifferentiation and transdifferentiation,thus improving visual function and delaying retinal degenerative progression.METHODS:h ERO-RPCs were subretinally transplanted into Royal College of Surgeons(RCS)rats.Electroretinography(ERG)recording was performed at 4 and 8wk postoperation to assess retinal function.Using immunofluorescence,the changes in outer nuclear layer(ONL)thickness and retinal Müller glia were explored at 2,4,and 8wk postoperation.To verify the effect of h ERO-RPCs on Müller glia in vitro,we cocultured h ERO-RPCs with Müller glia with a Transwell system.After coculture,Ki67 staining and quantitative polymerase chain reaction(q PCR)were performed to measure the proliferation and m RNA levels of Müller glia respectively.Cell migration experiment was used to detect the effect of h ERO-RPCs on Müller glial migration.Comparisons between two groups were performed by the unpaired Student’s t-test,and comparisons among multiple groups were made with one-way ANOVA followed by Tukey’s multiple comparison test.RESULTS:The visual function and ONL thickness of RCS rats were significantly improved by transplantation of h ERO-RPCs at 4 and 8wk postoperation.In addition to inhibiting gliosis at 4 and 8wk postoperation,h ERO-RPCs significantly increased the expression of dedifferentiation-associated transcriptional factor in Müller glia and promoted the migration at 2,4 and 8wk postoperation,but not the transdifferentiation of these cells in RCS rats.In vitro,using the Transwell system,we found that h ERO-RPCs promoted the proliferation and migration of primary rat Müller glia and induced their dedifferentiation at the m RNA level.CONCLUSION:These results show that h ERO-RPCs might promote early dedifferentiation of Müller glia,which may provide novel insights into the mechanisms of stem cell therapy and Müller glial reprogramming,contributing to the development of novel therapies for retinal degeneration disorders.

Two faces of Schwann cell dedifferentiation in peripheral neurodegenerative diseases:pro-demyelinating and axon-preservative functions

Schwann cells are glial cells that are responsible for the synthesis and maintenance of the myelin sheath in the peripheral nerve system. Under pathological conditions, such as physical nerve injury and inflammatory neuropathies, Schwann cells undergo a substantial phenotype transformation that is not related to their intended function. For example, Schwann cells dedifferentiate into immature states and thereby cease to express myelin genes after nerve injury.

Temporal Integrative Omics Reveals an Increase in Nondegradative Ubiquitylation during Primary Hepatocyte Dedifferentiation

Primary hepatocytes(PHCs)are widely used in various fields,but the progressive deterioration of liverspecific features in vitro significantly limits their application.While the transcriptional regulation and whole cell proteome(WCP)of PHCs have been extensively studied,only a small number of studies have addressed the role of posttranslational modifications in this process.To elucidate the underlying mechanisms that induce dedifferentiation,we carried out parallel quantifications of the transcriptome,WCP,ubiquitinome,and phosphoproteome of rat PHCs after 0,6,12,24,and 48 h of in vitro culture.Our data constitute a detailed proteomic analysis of dedifferentiated PHCs including 2196 proteins,2056 ubiquitinated sites,and 4932 phosphorylated peptides.We revealed a low correlation between the transcriptome and WCP during dedifferentiation.A combined analysis of the ubiquitinome with the corresponding WCP indicated that the dedifferentiation of PHCs led to an increase in nondegradative K27 ubiquitination.Functional analysis of the altered phosphoproteins suggested a significant enrichment in ferroptosis.In all,404 proteins with both ubiquitination and phosphorylation were identified to be involved in critical metabolic events.Furthermore,Ptbph Hnqjd,Hnrnpu,and Srrm2 were identified as hub genes.Taken together,our data provide new insights into proteome dynamics during PHC dedifferentiation and potential targets to inhibit the dedifferentiation process.

Effect of Qishen decoction on dedifferentiation of sinusoidal endothelial cells by autophagy

Objective:To observe the effect of Qishen decoction on dedifferentiation and autophagy of liver sinusoid endothelial cells(LSEC);Methods:LSEC were randomly divided into the control group,model group,Qishen Decoction low,medium,high dose group,and inhibitor group.The model was induced by 100μg/ml oxidized low-density lipoprotein(oxLDL)for 24 hours,and the corresponding drugs or medicated serum were given for intervention.The expression levels of VEGFR2 and ET1 were detected by RT-qPCR and immunofluorescence staining,the ultrastructure of LSEC was detected by transmission electron microscopy,the content of NO was detected by ELISA,the expression levels of autophagy related proteins(LC3BI,LC3BⅡand p62)and endothelial function related proteins(eNOS and p-eNOS)were detected by western blot;Results:The results of transmission electron microscopy showed that Qishen decoction medicated serum could increase the number of fenestra and autophagy in LSEC cells,and inhibit the formation of basement membrane under endothelium.Compared with the model group,Qishen decoction medicated serum could significantly up-regulate the expression level of VEGFR2 mRNA and protein in LSEC,down regulate the expression level of ET1 mRNA and protein,the difference was statistically significant(P<0.05).In addition,Qishen decoction medicated serum could significantly increase the expression of LC3BII,p-eNOS,eNOS protein and the ratio of LC3BII/LC3BI,p-eNOS/eNOS,and reduce the expression of LC3BI and p62 protein in LSEC,which is statistically significant compared with the model group(P<0.05).Conclusion:Qishen decoction can inhibit the dedifferentiation of LSEC by promoting the autophagy level of LSEC,and then play an anti-fibrosis role.

High Concentration of Spermine Induces the Dedifferentiation of Somatic Cells into Pluripotent Stem Cells

Cancer tissues contain cancer stem cells (CSCs), which play important roles in cancer metastasis. However, the mechanisms through which cancer cells dedifferentiate into stem cells have not yet been elucidated. In this study, the effects of high concentrations of polyamines produced in cancer cells on dedifferentiation were examined. The results showed that when normal human fibroblasts were cultured with high concentrations of spermine, the obtained polyamine-induced cells expressed alkaline phosphatase and marker proteins of pluripotent stem cells, although apoptosis occurred in most cells. In contrast, another polyamine-induced stem (PIS) cell line (Spe-2 PIS cells), obtained by culture in medium containing Rock, p53, and Bax inhibitors plus spermine, did not show signs of apoptosis. These Spe-2 PIS cells expressed marker proteins of pluripotent stem cells and differentiated into cardiomyocytes, brown adipocytes, and nerve cells. These results suggest that a high concentration of spermine, which often induces apoptosis in normal cells, has the capacity to dedifferentiate somatic cells into pluripotent stem cells and may be associated with the dedifferentiation of cancer cells, which continuously produce high concentrations of spermine. Moreover, the procedure to obtain Spe-2 PIS cells, which is simple and efficient, may have potential applications in regenerative medicine.

SOX2/DRD2 signaling pathway facilitates astrocytic dedifferentiation in cerebral ischemic mice

Objective:To explore the effects of dopamine receptor D2(DRD2)on astrocytic dedifferentiation based on SOX2-regulated genes in neural stem cells(NSCs)and astrocytes.Methods:Immunofluorescence staining and SOX2-GFP mice were used to examine the lineage differentiation of SOX2-positive cells during the development of cerebral cortex.Primary NSCs/astrocytes culture,ChIP-seq and Western Blot were adopted to analyze and verify the expression of candidate genes.Pharmacological manipulation,neurosphere formation,photochemical ischemia,immunofluorescence staining and behavior tests were adopted to evaluate the effects of activating DRD2 signaling on astrocytic dedifferentiation.Results:Immunofluorescence staining demonstrated the NSC-astrocyte switch of SOX2-expression in the normal development of cerebral cortex.ChIP-seq revealed enrichment of DRD2 signaling by SOX2-bound enhancers in NSCs and SOX2-bound promoters in astrocytes.Western Blot and immunofluorescence staining verified the expression of DRD2 in NSCs and reactive astrocytes.Application of quinagolide hydrocholoride(QH),an agonist of DRD2,significantly promoted astrocytic dedifferentiation both in vitro and in vivo following ischemia.In addition,quinagolide hydrocholoride treatment improved locomotion recovery.Conclusion:Activating DRD2 signaling facilitates astrocytic dedifferentiation and may be used to treat ischemic stroke.

MicroRNA-24 promotes pancreatic beta cells toward dedifferentiation to avoid endoplasmic reticulum stress-induced apoptosis

Current research indicates that beta cell loss in type 2 diabetes may be attributed to beta cell dedifferentiation rather than apoptosis;however,the mechanisms by which this occurs remain poorly understood.Our previous study demonstrated that elevation of microRNA-24(miR-24)in a diabetic setting caused beta cell dysfunction and replicative deficiency.In this study,we focused on the role of miR-24 in beta cell apoptosis and dedifferentiation under endoplasmic reticulum(ER)stress conditions.We found that miR-24 overabundance protected beta cells from thapsigargin-induced apoptosis at the cost of accelerating the impairment of glucosestimulated insulin secretion(GSIS)and enhancing the presence of dedifferentiation markers.Ingenuity?Pathway Analysis(IPA)revealed that elevation of miR-24 had an inhibitory effect on XBP1 and ATF4,which are downstream effectors of two key branches of ER stress,by inhibiting its direct target,Irela.Notably,elevated miR-24 initiated another pathway that targeted Mafa and decreased GSIS function in surviving beta cells,thus guiding their dedifferentiation under ER stress conditions.Our results demonstrated that the elevated miR-24,to the utmost extent,preserves beta cell mass by inhibiting apoptosis and inducing dedifFerentiation.This study not only provides a novel mechanism by which miR-24 dominates beta cell turnover under persistent metabolic stress but also offers a therapeutic consideration for treating diabetes by inducing dedifferentiated beta cells to re-differentiation.

Intestinal epithelial plasticity and regeneration via cell dedifferentiation

The intestinal epithelium possesses a great capacity of self-renewal under normal homeostatic conditions and of regeneration upon damages.The renewal and regenerative processes are driven by intestinal stem cells(ISCs),which reside at the base of crypts and are marked by Lgr5.As Lgr5^(+)ISCs undergo fast cycling and are vulnerable to damages,there must be other types of cells that can replenish the lost Lgr5^(+)ISCs and then regenerate the damage epithelium.In addition to Lgr5^(+)ISCs,quiescent ISCs at the+4 position in the crypt have been proposed to convert to Lgr5^(+)ISCs during regeneration.However,this“reserve stem cell”model still remains controversial.Different from the traditional view of a hierarchical organization of the intestinal epithelium,recent works support the dynamic“dedifferentiation”model,in which various cell types within the epithelium can de-differentiate to revert to the stem cell state and then regenerate the epithelium upon tissue injury.Here,we provide an overview of the cell identity and features of two distinct models and discuss the possible mechanisms underlying the intestinal epithelial plasticity.

Regeneration of Cytologically Stable Plants Through Dedifferentiation, Redifferentiation, and Artificial Seeds in Spathoglottis plicata Blume.(Orchidaceae)

Spathoglottis plicata Blume. is a horticulturally important vulnerable ground orchid with beautiful flowers blooming round the year. Highfrequency protocorm-like body(PLB) formation was established via callus culture from vegetative tissues of in vitro germinated seedlings of S.plicata. Media containing MS salts and Gamborg's B5 vitamins supplemented with 1.0 mg·L^(-1) 2,4-dichlorophenoxyacetic acid(2,4-D), 3.0 mg·L^(-1) α-naphthaleneacetic acid(NAA), 1.0 mg·L^(-1) kinetin(KIN), and 10%(v/v) ‘Aloe vera gel'(Av G) were effective in fragile calli induction. A maximum of(22.3 ± 0.52) PLBs were induced from about 250 mg callus within 45–55 days in the presence of 2.0 mg·L^(-1) NAA and 3.0 mg·L^(-1) 6-benzylaminopurine(BAP). Briefly, 3.0% sodium alginate was found to be most suitable for the formation of an appropriate shape and good germination rates(86.7%)of artificial seeds. Out of three different temperatures(4, 15, and 24 °C), the best result was achieved at 4 °C with 66.7% germinability even after90 days of storage. Plantlets were acclimatized with 86.6% survival rate and 76.3% of these plants produced flowers within 12–15 months of field transfer. Chromosomal studies revealed cytological stability of all regenerants containing 2 n = 40 chromosomes as in the parental plants.The present protocol can be applied reliably for the purposes of large-scale commercial propagation and short-term conservation of this orchid.

Three-dimensional (3D) hydrogel serves as a platform to identify potential markers of chondrocyte dedifferentiation by combining RNA sequencing

Dedifferentiation of chondrocyte greatly restricts its function and application,however,it is poorly understood except a small number of canonical markers.The non-cell-adhesive property endows polysaccharide hydrogel with the ability to maintain chondrocyte phenotype,which can serve as a platform to identify new molecular markers and therapeutic targets of chondrocyte dedifferentiation.In this study,the high-throughput RNA sequencing(RNA-seq)was first performed on articular chondrocytes at primary(P0)and passage 1(P1)stages to explore the global alteration of gene expression along with chondrocyte dedifferentiation.Significantly,several potential marker genes,such as PFKFB3,KDM6B,had been identified via comparatively analyzing their expression in P0 and P1 chondrocytes as well as in 3D constructs(i.e.chondrocyte-laden alginate hydrogel and HA-MA hydrogel)at both mRNA and protein level.Besides,the changes in cellular morphology and enriched pathway of differentially expressed genes during chondrocyte dedifferentiation was studied in detail.This study developed the use of hydrogel as a platform to investigate chondrocyte dedifferentiation;the results provided new molecular markers and potential therapeutic targets of chondrocyte dedifferentiation.

GRB10 regulates β-cell mass by inhibiting β-cell proliferation and stimulating β-cell dedifferentiation

Decreased functional β-cell mass is the hallmark of diabetes, but the cause of this metabolic defect remains elusive. Here, we show that the levels of the growth factor receptor-bound protein 10(GRB10), a negative regulator of insulin and m TORC1 signaling, are markedly induced in islets of diabetic mice and high glucose-treated insulinoma cell line INS-1 cells. β-cell-specific knockout of Grb10 in mice increased β-cell mass and improved β-cell function. Grb10-deficient β-cells exhibit enhanced m TORC1 signaling and reduced β-cell dedifferentiation, which could be blocked by rapamycin. On the contrary, Grb10 overexpression induced β-cell dedifferentiation in MIN6 cells. Our study identifies GRB10 as a critical regulator of β-cell dedifferentiation and β-cell mass, which exerts its effect by inhibiting m TORC1 signaling.

Aberrant DNA repair as a potential contributor for the clonal evolution in subsets of anaplastic thyroid carcinomas arising through dedifferentiation: implications for future therapeutic algorithms?

Well-differentiated thyroid carcinoma(WDTC,including papillary thyroid carcinoma and follicular thyroid carcinoma)are fairly slow-growing tumors with an overall low mortality due to the efficacy of combinatory surgery and postoperative radioiodine therapy.Subsets of WDTCs may dedifferentiate into poorly differentiated thyroid carcinoma(PDTC)and anaplastic thyroid carcinoma(ATC),of which especially the latter has an exceptionally poor patient outcome.The underlying genetics responsible for this tumor progression is only partly understood,and is complicated by the fact that subgroups of ATCs are thought to arise de novo without a demonstrable,pre-existing WDTC.Even so,recent advances using next generation sequencing(NGS)techniques have identified a genetic link between WDTCs and ATCs,suggesting a step-wise accumulation of mutations driving the loss of differentiation for most cases.In this Commentary,recent findings from an NGS study on synchronous FTC,PDTC,and ATC tumor components from the same patient are highlighted.By using whole-genome data,clonality analyses identified a chief ancestral clone carrying mutations in TP53-associated signaling networks regulating genes involved in DNA repair,with sub-clones in each tumor component that were identified also in the less differentiated,neighboring tumor.Moreover,mutational signatures suggested a general mismatch repair(MMR)deficiency along with microsatellite instability.These findings support the chained progression model of dedifferentiation in thyroid cancer,and pinpoint a central role for defective DNA repair.Since effective treatment modalities for ATCs are urgently needed,studies regarding therapeutic agents specifically targeting defective MMR in dedifferentiated thyroid carcinoma could be pursued.

Primary dedifferentiated chondrosarcoma of the lung with a 4-year history of breast cancer:A case report

BACKGROUND Primary dedifferentiated chondrosarcoma(DDCS)of the lung is extremely rare and has a poor prognosis,especially in patients with a history of carcinomas and related treatment.Herein,we report a case of primary DDCS of the lung in a patient with a 4-year history of breast cancer and related treatment.CASE SUMMARY A 49-year-old woman was admitted to our hospital with complaints of headache,dizziness,slurred speech,and dyskinesia in May 2021.Computed tomography(CT)examinations showed multiple nodules in the brain,vertebral body,and both lungs with multiple enlarged lymph nodes in the right hilum and mediastinum,which were considered metastases of breast cancer.No obvious mass was discovered in the right hilum.After several months of related administration,the patient's headache disappeared,and her condition improved.However,new problems of asthma,dyspnea,cough,and restricted activity appeared in late November 2021.Although the CT scan indicated that the lesions in the brain,lung,and vertebral body had shrunk or disappeared,a soft tissue density lesion appeared in her right hilum and blocked the bronchial lumen.To relieve her dyspnea,part of the mass was resected,and a stent was placed via fiberoptic bronchoscopy.Following a complete pathological examination of the tumor,it was confirmed to be a primary DDCS of the lung.The patient then received two rounds of systemic chemotherapy with a regimen of cisplatin+ifosfamide+doxorubicin hydrochloride liposome,palliative radiotherapy for the tumor in her right lung,and four cycles of systemic chemotherapy and targeted therapy with a regimen of temozolomide combined with bevacizumab successively.She was in stable condition after the completion of the systemic chemotherapy and targeted therapy but underwent rapid progression after lung radiotherapy.The CT examinations showed multiple nodules in the brain and in both lungs,and the tumor in the right hilum was increased in size.CONCLUSION This case revealed a rare primary DDCS of the lung with a medical history of breast cancer,meaning a worse prognosis and making it more difficult to treat.

Giant dedifferentiated liposarcoma of the gastrocolic ligament:A case report

BACKGROUND Dedifferentiated liposarcoma(DDLS)has a worse prognosis and occurs most commonly in the retroperitoneal region and rarely in the intraperitoneal region.Histological diagnosis was revolutionized by the combined contributions of histoimmuno-chemistry and molecular biology.Aside from surgery,there is no consensus on the optimal treatment for this chemoresistant cancer.CASE SUMMARY A thirty-year-old black female presented with a large painful abdominal mass occupying nearly the entire abdomen and progressive weight loss was admitted for surgery.Abdominal computed tomography showed a large heterogeneous mass of the mesentery that was sized 18 cm×16 cm in size and had heterogeneous contrast enhancement.During laparotomy,en bloc excision of the large and multilobulated gastrocolic ligament mass was performed.The initial postoperative histopathological diagnosis was undifferentiated sarcoma.Finally,the results of immunohistochemistry and molecular biology allowed us to confirm the diagnosis of DDLS.The tumour followed an aggressive evolution with diffuse metastasis,causing the death of the patient less than 5 mo after the operation.CONCLUSION Dedifferentiated liposarcomas are rare tumours that typically originate in the retroperitoneum but may arise in unexpected locations.

Axon degeneration： make the Schwann cell great again

Axonal degeneration is a pivotal feature of many neurodegenerative conditions and substantially accounts for neurological morbidity. A widely used experimental model to study the mechanisms of axonal degeneration is Wallerian degeneration （WD）, which occurs after acute axonal injury. In the peripheral nervous system （PNS）, WD is characterized by swift dismantling and clearance of injured axons with their myelin sheaths. This is a prerequisite for successful axonal regeneration. In the central nervous system （CNS）, WD is much slower, which significantly contributes to failed axonal regeneration. Although it is well documented that Schwann cells （SCs） have a critical role in the regenerative potential of the PNS, to date we have only scarce knowledge as to how SCs ＇sense＇ axonal injury and immediately respond to it. In this regard, it remains unknown as to whether SCs play the role of a passive bystander or an active director during the execution of the highly orchestrated disintegration program of axons. Older reports, together with more recent studies, suggest that SCs mount dynamic injury responses minutes after axonal injury, long before axonal breakdown occurs. The swift SC response to axonal injury could play either a pro degenerative role, or alternatively a supportive role, to the integrity of distressed axons that have not yet committed to degenerate. Indeed, supporting the latter concept, recent 昀ndings in a chronic PNS neurodegeneration model indicate that deactivation of a key molecule promoting SC injury responses exacerbates axonal loss. If this holds true in a broader spectrum of conditions, it may provide the grounds for the development of new glia-centric therapeutic approaches to counteract axonal loss.

Activation of extracellular signal-related kinases 1 and 2 in Sertoli cells in experimentally cryptorchid rhesus monkeys

Aim： To assess the spatiotemporal changes in the expression of extracellular signal-regulated kinases 1 and 2 （ERK1/ 2）, c-Jun N-terminal kinases （JNK） and p38 mitogen-activated protein kinases （MAPK） in response to heat stress in the cryptorchid testis, and to investigate a possible relation to Sertoli cell dedifferentiation. Methods： Immunohistochemistry and western blot were used to examine the expression and activation of ERK1/2, p38 and JNK in the cryptorchid testis at various stages after experimental cryptorchidism. Results： The abdominal temperature did not obviously change the total ERK1/2 expression but significantly activated phospho-ERK1/2 in the Sertoli cells of the cryptorchid testis. Heat stress increased total JNK expression in the Sertoli cells of the cryptorchid testis but did not activate phospho-JNK. Neither total p38 nor phospho-p38 was induced by heat stress in the Sertoli cells of the cryptorchid testis. Changes in the spatiotemporal expression of cytokeratin 18 （CK18）, a marker of immature or undifferentiated Sertoli cells, were induced in the cryptorchid testis in a pattern similar to the activation of ERK1/2. Condusion： The activation of ERK1/2 in the testis may be related to dedifferentiation of Sertoli cells under heat stress induced by experimental cryptorchidism.

Pancreatic β cell regeneration induced by clinical and preclinical agents

Diabetes,one of the most common chronic diseases in the modern world,has pancreaticβcell deficiency as a major part of its pathophysiological mechanism.Pancreatic regeneration is a potential therapeutic strategy for the recovery ofβcell loss.However,endocrine islets have limited regenerative capacity,especially in adult humans.Almost all hypoglycemic drugs can protectβcells by inhibitingβcell apoptosis and dedifferentiation via correction of hyperglycemia and amelioration of the consequent inflammation and oxidative stress.Several agents,including glucagon-like peptide-1 andγ-aminobutyric acid,have been shown to promoteβcell proliferation,which is considered the main source of the regeneratedβcells in adult rodents,but with less clarity in humans.Pancreatic progenitor cells might exist and be activated under particular circumstances.Artemisinins andγ-aminobutyric acid can induceα-to-βcell conversion,although some disputes exist.Intestinal endocrine progenitors can transdeterminate into insulin-producing cells in the gut after FoxO1 deletion,and pharmacological research into FoxO1 inhibition is ongoing.Other cells,including pancreatic acinar cells,can transdifferentiate intoβcells,and clinical and preclinical strategies are currently underway.In this review,we summarize the clinical and preclinical agents used in different approaches forβcell regeneration and make some suggestions regarding future perspectives for clinical application.

Adult neurogenesis from reprogrammed astrocytes

The details of adult neurogenesis,including environmental triggers,region specificity,and species homology remain an area of intense investigation.Slowing or halting age-related cognitive dysfunction,or restoring neurons lost to disease or injury represent just a fraction of potential therapeutic applications.New neurons can derive from stem cells,pluripotent neural progenitor cells,or non-neuronal glial cells,such as astrocytes.Astrocytes must be epigenetically"reprogrammed"to become neurons,which can occur both naturally in vivo,and via artificial exogenous treatments.While neural progenitor cells are localized to a few neurogenic zones in the adult brain,astrocytes populate almost every brain structure.In this review,we will summarize recent research into neurogenesis that arises from conversion of post-mitotic astrocytes,detail the genetic and epigenetic pathways that regulate this process,and discuss the possible clinical relevance in supplementing stem-cell neurogenic therapies.

Segment boundaries of the adult rat epididymis limit interstitial signaling by potential paracrine factors and segments lose differential gene expression after efferent duct ligation

The epididymis is divided into caput, corpus and cauda regions, organized into intraregional segments separated by connective tissue septa （CTS）. In the adult rat and mouse these segments are highly differentiated. Regulation of these segments is by endocrine, lumicrine and paracrine factors, the relative importance of which remains under investigation. Here, the ability of the CTS to limit signaling in the interstitial compartment is reviewed as is the effect of 15 days of unilateral efferent duct ligation （EDL） on ipsilateral segmental transcriptional profiles. Inter-segmental microperifusions of epidermal growth factor （EGF）, vascular endothelial growth factor （VEGFA） and fibroblast growth factor 2 （FGF2） increased phosphorylation of mitogen activated protein kinase （MAPK） in segments 1 and 2 of the rat epididymis and the effects of all factors were limited by the CTS separating the segments. Microan＇ay analysis of segmental gene expression determined the effect of 15 days of unilateral EDL on the transcriptome-wide gene expression of rat segments 1-4. Over 11 000 genes were expressed in each of the four segments and over 2 000 transcripts in segment 1 responded to deprivation of testicular lumicrine factors. Segments 1 and 2 of control tissues were the most transcriptionally different and EDL had its greatest effects there. In the absence of lumicrine factors, all four segments regressed to a transcriptionally undifferentiated state, consistent with the less differentiated histology. Deprivation of lumicrine factors could stimulate an individual gene＇s expression in some segments yet suppress it in others. Such results reveal a higher complexity of the regulation of rat epididymal segments than that is generally appreciated. （Asian J Androl 2007 July; 9： 565-573）

miR-30c promotes Schwann cell remyelination following peripheral nerve injury

Differential expression of mi RNAs occurs in injured proximal nerve stumps and includes mi RNAs that are firstly down-regulated and then gradually up-regulated following nerve injury.These mi RNAs might be related to a Schwann cell phenotypic switch.mi R-30 c,as a member of this group,was further investigated in the current study.Sprague-Dawley rats underwent sciatic nerve transection and proximal nerve stumps were collected at 1,4,7,14,21,and 28 days post injury for analysis.Following sciatic nerve injury,mi R-30 c was down-regulated,reaching a minimum on day 4,and was then upregulated to normal levels.Schwann cells were isolated from neonatal rat sciatic nerve stumps,then transfected with mi R-30 c agomir and co-cultured in vitro with dorsal root ganglia.The enhanced expression of mi R-30 c robustly increased the amount of myelin-associated protein in the co-cultured dorsal root ganglia and Schwann cells.We then modeled sciatic nerve crush injury in vivo in Sprague-Dawley rats and tested the effect of perineural injection of mi R-30 c agomir on myelin sheath regeneration.Fourteen days after surgery,sciatic nerve stumps were harvested and subjected to immunohistochemistry,western blot analysis,and transmission electron microscopy.The direct injection of mi R-30 c stimulated the formation of myelin sheath,thus contributing to peripheral nerve regeneration.Overall,our findings indicate that mi R-30 c can promote Schwann cell myelination following peripheral nerve injury.The functional study of mi R-30 c will benefit the discovery of new therapeutic targets and the development of new treatment strategies for peripheral nerve regeneration.