Fibroblast Growth Factor-16 Research Articles

Transcription analysis of chicken embryo fibroblast cells infected with the recombinant avian leukosis virus isolate GX14FF03.

Infection with recombinant avian leukosis virus (ALV) has previously been linked to malignancies and immunosuppression. However, the processes behind the unique pathophysiology of recombinant ALV are poorly understood. In this study, we analyzed gene expression patterns in chicken fibroblast cells (CEFs) infected with the recombinant ALV isolate GX14FF03 and used the RNA-seq technique to perform a complete analysis of the transcribed mRNAs. A total of 907 significant differentially expressed genes (SDEGs) were identified. Among these SDEGs, the most significantly upregulated gene was interleukin 8-like 1 (IL8L1), while the most significantly downregulated gene was fibroblast growth factor 16 (FGF16). The 907 SDGEs were highly enriched (p < 0.05) for 252 Gene Ontology (GO) terms, including 197 BP, 3 CC, and 52 MF. According to KEGG data analysis, SDEGs are implicated in eight significant pathways (p < 0.05). Furthermore, protein-protein interaction (PPI) network analysis revealed that IL8L1 interacts with 17 genes. These findings shed light on the molecular mechanisms involved in recombinant ALV infection by showing the mRNA expression profile in CEFs infected with GX14FF03 virus.

Bone morphogenetic protein 15 supplementation enhances cumulus expansion, nuclear maturation and progesterone production of in vitro-matured bovine cumulus-oocyte complexes.

In vitro embryo production (IVP) efficiency is reduced when compared to in vivo. The basic knowledge of bovine in vitro oocyte maturation (IVM) mechanisms provides support to improve in vitro embryo production yields. The present study assessed the effects of bone morphogenetic protein 15 (BMP15), fibroblast growth factor 16 (FGF16) and their combined action on cumulus cells (CC) expansion, oocyte and CC DNA fragmentation, oocyte nuclear maturation, energetic metabolism and progesterone production in bovine IVM. Cumulus-oocyte complexes (COC) were matured in control or supplemented media containing BMP15 (100ng/ml), FGF16 (10ng/ml) or BMP15 combined with FGF16; and assessed at 0 and 22hr of IVM. BMP15 alone or its association with FGF16 enhanced cumulus expansion. BMP15 decreased DNA fragmentation in both CC and oocytes, and improved oocyte nuclear maturation rate. In addition, BMP15 increased CC progesterone production, an effect not previously reported. The present study reinforces previous data pointing to a beneficial influence of BMP15 during IVM, while providing novel evidence that the underlying mechanisms involve increased progesterone production.

Molecular characterization of fibroblast growth factor-16 and its role in promoting the differentiation of intramuscular preadipocytes in goat

Fat metabolism is an important and complex biochemical reaction in vivo and is regulated by many factors. Recently, the findings on high expression of fibroblast growth factor-16 (FGF16) in brown adipose tissue have led to an interest in exploring its role in lipogenesis and lipid metabolism. The study cloned the goat’s FGF16 gene 624 bp long, including the complete open reading frame that encodes 207 amino acids. We found that FGF16 expression is highest in goat kidneys and hearts, followed by subcutaneous fat and triceps. Moreover, the expression of FGF16 reached its peak on the 2nd day of adipocyte differentiation (P < 0.01) and then decreased significantly. We used overexpression and interference to study the function of FGF16 gene in goat intramuscular preadipocytes. Silencing of FGF16 decreased adipocytes lipid droplet aggregation and triglyceride synthesis. This is in contrast to the situation where FGF16 is overexpressed. Furthermore, knockdown of FGF16 also caused down-regulated expression of genes associated with adipocyte differentiation including CCAAT enhancer-binding protein beta (P < 0.01), fatty acid-binding protein-2 (P < 0.01) and sterol regulatory element binding protein-1 (P < 0.05), but the preadipocyte factor-1 was up-regulated. At the same time, the genes adipose triglyceride lipase (P < 0.01) and hormone-sensitive lipase (P < 0.05) associated with triglyceride breakdown were highly expressed. Next, we locked the fibroblast growth factor receptor-4 (FGFR4) through the protein interaction network and interfering with FGF16 to significantly reduce FGFR4 expression. It was found that the expression profile of FGFR4 in adipocyte differentiation was highly similar to that of FGF16. Overexpression and interference methods confirmed that FGFR4 and FGF16 have the same promoting function in adipocyte differentiation. Finally, using co-transfection technology, pc-FGF16 and siRNA-FGFR4, siRNA2-FGF16 and siRNA-FGFR4 were combined to treat adipocytes separately. It was found that in the case of overexpression of FGF16, cell lipid secretion and triglyceride synthesis showed a trend of first increase and then decrease with increasing interference concentration. In the case of interference with FGF16, lipid secretion and triglyceride synthesis showed a downward trend with the increase of interference concentration. These findings illustrated that FGF16 mediates adipocyte differentiation via receptor FGFR4 expression and contributed to further study of the functional role of FGF16 in goat fat formation.

MiR-372-3p is a potential diagnostic factor for diabetic nephropathy and modulates high glucose-induced glomerular endothelial cell dysfunction via targeting fibroblast growth factor-16.

Previous studies have reported that microRNAs are implicated in the pathogenesis of diabetic nephropathy (DN). In this study, the underlying molecular mechanisms and diagnostic significance of miR-372-3p were investigated in the process of DN. Cell proliferation and apoptosis were measured using MTT and Annexin V-FITC double staining, respectively. RT-qPCR and western blotting were used to measure the expression levels of mRNA and protein. The diagnostic power of miR-372-3p in plasma for DN was evaluated using the receiver operating characteristics (ROC) curves and the area under the ROC curves (AUC). miR microarray analysis revealed that 126 miRs were significantly differentially expressed in response to high glucose stimulation. Among these miRs, high glucose stimulated miR-372-3p expression at the highest level. In vitro experimental measurements showed that knockdown of miR-372-3p showed the ability to reverse high glucose-induced glomerular endothelial cell apoptosis and impairment of eNOS/NO bioactivity. Mechanistic analysis revealed that fibroblast growth factor-16 (FGF-16) as a direct of miR-372-3p protected against high glucose-induced glomerular endothelial cell dysfunction. ROC analysis revealed that the diagnostic value of miR-372-3p, miR-15a or miR-372-3p combined with miR-15a in type 2 diabetes mellitus patients (AUC = 0.841, p < 0.001; AUC = 0.822, p < 0.001 or AUC = 0.922, p < 0.001) with DN was better than in type 1 diabetes mellitus patients (AUC = 0.805, p < 0.001; AUC = 0.722, p < 0.001 or AUC = 0.865, p < 0.001) with DN. miR-372-3p might be a valuable therapeutic target and diagnostic marker for patients with DN.

Fibroblast growth factor 16 stimulates proliferation but blocks differentiation of rat stem Leydig cells during regeneration.

ObjectivesWe aim to investigate the effects of fibroblast growth factor 16 (FGF16) on Leydig cell regeneration in ethane dimethane sulphonate (EDS)‐treated rat testis.MethodsWe intraperitoneally inject 75 mg/kg EDS to adult male Sprague Dawley rats and then intratesticularly inject FGF16 (0, 10 and 100 ng/testis/day) from post‐EDS day 14 for 14 days. We investigate serum hormone levels, Leydig cell number, gene and protein expression in vivo. We also explore the effects of FGF16 treatment on stem Leydig cell proliferation in vitro.ResultsFGF16 lowers serum testosterone levels (21.6% of the control at a dose of 100 ng/testis) without affecting the levels of luteinizing hormone (LH) and follicle‐stimulating hormone (FSH) on post‐EDS day 28 in vivo. FGF16 increases Leydig cell number at doses of 10 and 100 ng/mg without affecting Sertoli cell number, increases the percentage of PCNA‐positive Leydig cells, and down‐regulates the expression of Leydig cell genes (Lhcgr, Scarb1, Star, Cyp11a1, Cyp17a1 and Hsd17b3) and Sertoli cell genes (Fshr, Dhh and Sox9) and their proteins in vivo. FGF16 increases phosphorylation of AKT1 and AKT2 as well as EKR1/2 in vivo, indicating that it possibly acts via AKT1/ATK2 and ERK1/2 pathways. FGF16 also lowers medium testosterone levels and down‐regulates the expression of Leydig cell genes (Lhcgr, Scarb1, Star, Cyp11a1, Cyp17a1 and Hsd17b3) but increases EdU incorporation into stem Leydig cells in vitro.ConclusionsThese data suggest that FGF16 stimulates stem and progenitor Leydig cell proliferation but blocks their differentiation, thus lowering testosterone biosynthesis.

Secretome Screening Reveals Fibroblast Growth Factors as Novel Inhibitors of Viral Replication.

Cellular antiviral programs can efficiently inhibit viral infection. These programs are often initiated through signaling cascades induced by secreted proteins, such as type I interferons, interleukin-6 (IL-6), or tumor necrosis factor alpha (TNF-α). In the present study, we generated an arrayed library of 756 human secreted proteins to perform a secretome screen focused on the discovery of novel modulators of viral entry and/or replication. The individual secreted proteins were tested for the capacity to inhibit infection by two replication-competent recombinant vesicular stomatitis viruses (VSVs) with distinct glycoproteins utilizing different entry pathways. Fibroblast growth factor 16 (FGF16) was identified and confirmed as the most prominent novel inhibitor of both VSVs and therefore of viral replication, not entry. Importantly, an antiviral interferon signature was completely absent in FGF16-treated cells. Nevertheless, the antiviral effect of FGF16 is broad, as it was evident on multiple cell types and also on infection by coxsackievirus. In addition, other members of the FGF family also inhibited viral infection. Thus, our unbiased secretome screen revealed a novel protein family capable of inducing a cellular antiviral state. This previously unappreciated role of the FGF family may have implications for the development of new antivirals and the efficacy of oncolytic virus therapy.IMPORTANCE Viruses infect human cells in order to replicate, while human cells aim to resist infection. Several cellular antiviral programs have therefore evolved to resist infection. Knowledge of these programs is essential for the design of antiviral therapeutics in the future. The induction of antiviral programs is often initiated by secreted proteins, such as interferons. We hypothesized that other secreted proteins may also promote resistance to viral infection. Thus, we tested 756 human secreted proteins for the capacity to inhibit two pseudotypes of vesicular stomatitis virus (VSV). In this secretome screen on viral infection, we identified fibroblast growth factor 16 (FGF16) as a novel antiviral against multiple VSV pseudotypes as well as coxsackievirus. Subsequent testing of other FGF family members revealed that FGF signaling generally inhibits viral infection. This finding may lead to the development of new antivirals and may also be applicable for enhancing oncolytic virus therapy.

MiR-520f promotes cell aggressiveness by regulating fibroblast growth factor 16 in hepatocellular carcinoma.

Cancer metastasis is a multistep cellular process, which has be confirmed one of mainly causes of cancer associated-death in hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) participate in tumorigenesis function as either tumor suppressor genes or oncogenes. In order to elaborate the critical miRNAs and their targets in HCC, we compared the differential expression of miRNA between HCC tissues and normal tissues. Microarray analysis revealed there were several significantly up-expression miRNAs in HCC, compared to normal solid tissue. Among them, the expression of miR-520f was the most over-expression in HCC cell lines than that in human normal liver cells LO2, as well as up-regulated in HCC than that in the corresponding normal tissues. Moreover, Kaplan Meier-plotter analyses revealed that higher miR-520f levels were negatively correlated with poor overall survival. By applying bioinformatics methods to identify the targeting genes of miRNA, we demonstrated that fibroblast growth factor 16 (FGF16) was the miR-520f-targeted gene. Meanwhile, FGF16 exhibited similar expression patterns to miR-520f in HCC. Forced miR-520f expression accelerated HCC cells proliferation and aggressiveness in vitro and in vivo, whereas down-regulation of miR-520f caused an opposite outcome. Moreover, over-expression of FGF16 was closely related to the metastatic potential of HCC cells. Herein, we also confirmed that ectopic expression of FGF16 in HCC cells promoted proliferation, colony formation, and increased migration, invasion of HCC cells in vitro. Collectively, our results indicated that over-expression of miR-520f and FGF16 was positively associated with aggressive phenotypes and poor survival of patients with HCC, and miR-520f promoted HCC aggressive phenotypes by regulating the expression of FGF16. MiR-520f may be employed as a prognostic factor and therapeutic target for HCC.

High-yield of biologically active recombinant human fibroblast growth factor-16 in E. coli and its mechanism of proliferation in NCL-H460 cells

ABSTRACTFibroblast growth factor-16 (FGF16) is a member of FGF9 subfamily, which plays key role in promoting mitosis and cell survival, and also involved in embryonic development, cell growth, tissue repair, morphogenesis, tumor growth, and invasion. However, the successful high-yield purification of recombinant human fibroblast growth factor-16 (rhFGF16) protein has not been reported. In addition, lung cancer is a major cause of cancer-related deaths, which threats people’s lives and its incidence has continued to rise. Learning pathways or proteins, which involved in lung tumor progression will contribute to the development of early diagnosis and targeted therapy. FGF16 promoted proliferation and invasion behavior of SKOV-3 ovarian cancer cells, whose function may be similar in lung cancer. The hFGF16 was cloned into pET-3d and expressed in Escherichia coli BL21 (DE3) pLysS. Finally, obtained two forms of FGF16 that exhibited remarkable biological activity and the purity is over 95%, meanwhile, the yield of soluble 130 mg/100 g and insoluble 240 mg/100 g. Experiments demonstrated FGF16 could promote proliferation of NCL-H460 cells by activating Akt, Erk1/2, and p38 MAPK signaling, whereas JNK had no significant effect. In total, this optimized expression strategy enables significant quantity and activity of rhFGF16, thereby meeting its further pharmacological and clinical usages.

In Vitro and in Vivo Analyses Reveal Profound Effects of Fibroblast Growth Factor 16 as a Metabolic Regulator

The discovery of brown adipose tissue (BAT) as a key regulator of energy expenditure has sparked interest in identifying novel soluble factors capable of activating inducible BAT (iBAT) to combat obesity. Using a high content cell-based screen, we identified fibroblast growth factor 16 (FGF16) as a potent inducer of several physical and transcriptional characteristics analogous to those of both "classical" BAT and iBAT. Overexpression of Fgf16 in vivo recapitulated several of our in vitro findings, specifically the significant induction of the Ucp1 gene and UCP1 protein expression in inguinal white adipose tissue (iWAT), a common site for emergent active iBAT. Despite significant UCP1 up-regulation in iWAT and dramatic weight loss, the metabolic improvements observed due to Fgf16 overexpression in vivo were not the result of increased energy expenditure, as measured by indirect calorimetric assessment. Instead, a pattern of reduced food and water intake, combined with feces replete with lipid and bile acid, indicated a phenotype more akin to that of starvation and intestinal malabsorption. Gene expression analysis of the liver and ileum indicated alterations in several steps of bile acid metabolism, including hepatic synthesis and reabsorption. Histological analysis of intestinal tissue revealed profound abnormalities in support of this conclusion. The in vivo data, together with FGF receptor binding analysis, indicate that the in vivo outcome observed is the likely result of both direct and indirect mechanisms and probably involves multiple receptors. These results highlight the complexity of FGF signaling in the regulation of various metabolic processes.

Heart-specific expression of FGF-16 and a potential role in postnatal cardioprotection

Fibroblast growth factor 16 (FGF-16) was originally cloned from rat heart. Subsequent investigation of mouse FGF-16, including generation of null mice, revealed a specific pattern of expression in the endocardium and epicardium, and role for FGF-16 during embryonic heart development. FGF-16 is expressed mainly in brown adipose tissue during rat embryonic development, but is expressed mainly in the murine heart after birth. There is also an apparent switch from limited endocardial and epicardial expression in the embryo to the myocardium in the perinatal period. The FGF-16 gene and its location on the X chromosome are conserved between human and murine species, and no other member of the FGF family shows this pattern of spatial and temporal expression. The human and murine FGF-16 gene promoter regions also share an equivalent location for TATA sequences, as well as adjacent putative binding sites for transcription factors linked to cardiac expression and response to stress. Recent evidence has implicated nonsense mutation of FGF-16 with increased cardiovascular risk, and FGF-16 supplementation with cardioprotection. Here we review the important role of FGF-16 in embryonic heart development, its gene regulation, and evidence for FGF-16 as an endogenous and exogenous cardiac-specific and protective factor in the postnatal heart. Moreover, given the conservation of the FGF-16 gene and its chromosomal location between species, the question of support for a cardiac role in the human population is also considered.

Abstract 359: Negative Regulation Of The Fgf-16 Gene Promoter By Doxorubicin Is Associated With A Decrease In Nkx2.5 Binding

Doxorubicin (DOX) is a widely used and effective anti-cancer drug, but it is also cardiotoxic, which can lead to heart failure, and so strategies are needed to protect the heart. Fibroblast growth factor 16 (FGF-16) is preferentially expressed and released from cardiomyocytes after birth. Evidence suggests that FGF-16 decreases the risk of heart damage and limits the negative effects of heart remodeling (hypertrophy and fibrosis) after injury in vivo. Exogenous addition of FGF-16 also increased resistance to the loss of contractility in an isolated heart model of acute DOX-induced injury. Thus, how endogenous FGF-16 production and by extension function is affected by DOX treatment is of interest. The FGF-16 gene is highly conserved between human and murine species. Alignment of sequences indicates a conserved Nkx2.5 binding site in the proximal promoter region that is associated with a previously characterized TATA box. Nkx2.5 is an important factor in vertebrate heart development and congenital disease. Furthermore, Nkx2.5 RNA levels are decreased with DOX treatment. Thus, the possibility that DOX negatively affects FGF-16, perhaps through an effect on Nkx2.5 levels or binding, was investigated. Neonatal rat cardiomyocytes were treated with DOX, and FGF-16 RNA levels decreased 75% within 6 hours as assessed by qPCR. Inhibition of transcription with actinomycinD had no effect on the DOX-induced decrease in FGF-16 RNA levels. Further support for an effect of DOX on FGF-16 transcription was obtained by transfection of cardiomyocytes with a hybrid 747 bp mouse FGF-16 promoter/luciferase reporter gene that was treated with DOX; a significant decrease in luciferase activity was observed. Electrophoretic mobility shift and chromatin immunoprecipitation assays suggest reduced Nkx2.5 protein-DNA interaction with this site after DOX treatment in vitro and in situ, respectively. These data indicate that DOX decreases FGF-16 RNA expression and this correlates with a decrease in Nkx2.5 levels and association with the proximal promoter region. A direct effect of Nkx2.5 on FGF-16 promoter activity awaits further testing. Thus, a decrease or loss of FGF-16 synthesis might contribute to the DOX-induced damage and/or response to injury.

Embryonic Survival and Severity of Cardiac and Craniofacial Defects Are Affected by Genetic Background in Fibroblast Growth Factor-16 Null Mice

Disruption of the X-chromosome fibroblast growth factor 16 (Fgf-16) gene, a member of the FGF-9 subfamily with FGF-20, was linked with an effect on cardiac development in two independent studies. However, poor trabeculation with lethality by embryonic day (E) 11.5 was associated with only one, involving maintenance in Black Swiss (Bsw) versus C57BL/6 mice. The aim of this study was to examine the potential influence of genetic background through breeding the null mutation onto an alternate (C57BL/6) background. After three generations, 25% of Fgf-16(-/Y) mice survived to adulthood, which could be reversed by reducing the contribution of the C57BL/6 genetic background by back crossing to another strain. There was no significant difference between FGF-9 and FGF-20 RNA levels in Fgf-16 null versus wild-type mice regardless of strain. However, FGF-8 RNA levels were reduced significantly in Bsw but not C57BL/6 mice. FGF-8 is linked to anterior heart development and like the FGF-9 subfamily is reportedly expressed at E10.5. Like FGF-16, neuregulin as well as signaling via ErbB2 and ErbB4 receptors have been linked to trabeculae formation and cardiac development around E10.5. Basal neuregulin, ErbB2, and ErbB4 as well as FGF-8, FGF-9, and FGF-16 RNA levels varied in Bsw versus C57BL/6 mice. These data are consistent with the ability of genetic background to modify the phenotype and affect embryonic survival in Fgf-16 null mice.

FGF-16 is required for embryonic heart development

Fibroblast growth factor 16 (FGF-16) expression has previously been detected in mouse heart at mid-gestation in the endocardium and epicardium, suggesting a role in embryonic heart development. More specifically, exogenously applied FGF-16 has been shown to stimulate growth of embryonic myocardial cells in tissue explants. We have generated mice lacking FGF-16 by targeting the Fgf16 locus on the X chromosome. Elimination of Fgf16 expression resulted in embryonic death as early as day 11.5 (E11.5). External abnormalities, including hemorrhage in the heart and ventral body region as well as facial defects, began to appear in null embryos from E11.5. Morphological analysis of FGF-16 null hearts revealed cardiac defects including chamber dilation, thinning of the atrial and ventricular walls, and poor trabeculation, which were visible at E10.5 and more pronounced at E11.5. These findings indicate FGF-16 is required for embryonic heart development in mid-gestation through its positive effect on myocardial growth.

A Myocyte Enhancer Factor 2 (MEF2) Site Located in a Hypersensitive Region of the FGF16 Gene Locus Is Required for Preferential Promoter Activity in Neonatal Cardiac Myocytes

Fibroblast growth factor 16 (FGF16) is preferentially expressed in the heart after birth, suggesting its regulation is associated with tissue-specific chromatin remodeling and DNA-protein interactions. Here we have mapped the transcription initiation site of murine FGF16 to approximately 1.1 kilobases (kb) upstream of the translation start codon (ATG). Hybrid reporter genes directed by about 4.7 kb of upstream FGF16 DNA were expressed specifically in transfected neonatal rat cardiac myocytes, as well as in the heart of transgenic mice. A DNaseI hypersensitive site was mapped to a region about 1.2 kb upstream of the transcription initiation site in heart but not kidney tissue, and a nuclease protection assay gave evidence of a cardiac-specific protein-DNA interaction in this region. Deletion analysis indicated that a hybrid gene with 1205 bp but not 1054 bp of upstream DNA directed FGF16 promoter activity in transfected neonatal rat cardiac myocytes. We identified a putative myocyte enhancer factor 2 (MEF2)-binding site at nucleotides -1159/-1148, confirmed by electrophoretic mobility shift assay and MEF2 antibody binding. Mutation of the MEF2 site resulted in a blunting of FGF16 promoter activity in transfected neonatal rat cardiac myocytes. These data suggest that chromatin remodeling and MEF2 binding in the FGF16 promoter contribute to expression in the postnatal heart.

Cloning and bacterial expression of postnatal mouse heart FGF-16.

Fibroblast growth factor-16 (FGF-16) has been reported as the sixteenth member of the heparin sulphate proteoglycan binding growth factor family, which includes acidic and basic FGFs (FGF-1 and FGF-2), based on sequence similarity. The sequences of human (h) and rat (r) FGF-16 complimentary DNA (cDNA) sequences are known. Rat FGF-16 is expressed in brown adipose tissue during embryonic development but also shows some specificity for the postnatal heart. In spite of the importance of other FGF family members in cardiac physiology, there is scant information about FGF-16 function. As a first step towards exploiting mouse genetics in this regard, we have used reverse transcriptase-polymerase chain reaction and primers based on the rFGF-16 sequence to clone the adult mouse (m) FGF-16 cDNA. An mFGF-16 cDNA of 624 base pairs was generated. Based on sequence analysis, mFGF-16 and hFGF-16 share at least 95.2 and 99% nucleotide and amino acid similarity, respectively. In terms of other family members, FGF-16 is most closely related to FGF-9. When used as a radiolabeled probe, the mFGF-16 cDNA detected a single 1.8 kilobase transcript in adult mouse heart RNA. The mFGF-16 cDNA was also used to generate an amino-terminal poly-histidine tagged FGF-16 protein in bacteria. Using sodium dodecyl sulphate-polyacrylamide gel electrophoresis and taking into account the poly-histidine tag, an FGF-16 protein of 26.3 kDa was detected. The generation of cardiac mFGF-16 cDNA and a purified FGF-16 protein preparation are seen as important tools in the further characterization of FGF-16 expression and function in the mammalian heart.

Distribution and temporal expression of fibroblast growth factor-16 in the heart

Distribution and temporal expression of fibroblast growth factor-16 in the heart

Recombinant Rat Fibroblast Growth Factor-16: Structure and Biological Activity

Fibroblast growth factor-16 (FGF-16) is the most recent member of the FGF family to be cloned. Since the biologic activity of rat FGF-16 (rFGF-16) was unknown, and this protein has no apparent signal sequence, we transformed its entire cDNA intoEscherichia colifor high-level expression and further characterization of this novel protein. An attempt was made to purify the expressed protein from the supernatant of mechanically lysed cells using sequential cation-exchange chromatography. This resulted in a gradual loss of the protein as precipitate throughout the purification process. In addition to precipitation during purification, sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed that the partially purified materials showed a cluster of protein bands around 20k to 29k. Sequence analysis of the major bands indicated that two N-terminal truncations had occurred, duringE. colifermentation, purification, or both. The largest truncation resulted in the removal of the 34 N-terminal amino acids, including the initiation codon methionine. We cloned d34 rFGF-16, expressed the gene inE. coli,and developed a purification process for this form. Even with this truncated form, precipitation was a problem. We were largely able to overcome this problem, however, by including EDTA throughout the purification process. We have characterized the structure of purified d34 rFGF-16 extensively using circular dichroism, Fourier transform infrared spectroscopy, and sedimentation velocity analysis. These studies revealed that the protein has a distinct tertiary structure, consists primarily of β-strands, has a weak tendency to self-associate, and is fairly extended. We then performed biologic assays which showed that d34 rFGF-16 induces oligodendrocyte proliferationin vitro,and induces hepatocellular proliferation and increased liver weightin vivo.In summary, FGF-16, a novel FGF family member, has both unique structural and biological properties.