Igor Prudovsky, PhD

Faculty Scientist II


MS: Biology, Moscow University
PhD: Cell & Molecular Biology, Englehardt Institute of Molecular Biology
Dr Biol Sci: Englehardt Institute of Molecular Biology
Postdoctoral Training: Engelhardt Institute of Molecular Biology, Russian Academy of Sciences

Stressed-Induced Nonclassical Export of Growth Factors and Cytokines

Unlike other secreted proteins, the potent pro-angiogenic factor FGF1 and pro-inflammatory cytokine IL1alpha lack a signal peptide for classical secretion, and are released through Golgi-independent pathways. Cell stress induces the export of FGF1 and IL1 alpha. At stress, FGF1 and IL1alpha translocate to the vicinity of cell membrane (Fig 1), where they co-localize with cortical actin cytoskeleton to be further exported to the extracellular milieu.

Prudovsky Fig 1Fig 1. Heat shock-induced peripheral localization of FGF1 (green).

We found that the export of FGF1 relies on copper-dependent formation of a complex containing several secreted signal-peptide-less proteins: S100A13, sphingosine kinase 1 (SphK1), 40 kDa form of synaptotagmin 1 (p40 Syt1) and, apparently, annexin II (Anx II). A similar complex is required for stress-induced export of IL1alpha. The export of FGF1 release complex depends on transmembrane translocation of acidic phospholipids (Fig 2).

Prudovsky Fig 2Fig 2. Stress-induced FGF1 export.

Our current aims are to understand: 1.how the release complex assembles; 2. what is the role of actin cytoskeleton in the export of FGF1 and IL1α; 3.what is the molecular mechanism of transmembrane translocation of the release complex. In addition, to study the regulation of FGF1 export in vivo, we produced transgenic mice with FGF1 expression in endothelial cells and macrophages.

Regulation of Nonclassical Protein Export by Notch Signaling

FGF, IL1 and Notch are important regulators of angiogenesis and cancer growth. We found that the inhibition of Notch signaling results in strong spontaneous release of FGF1 (Figure 3) and IL1, and the increase of their expression.

Prudovsky Fig 3Fig 3. Inhibition of Notch signaling by a dn form of transcription factor MAML induces spontaneous FGF1 export.

Fibroblasts with inhibited Notch pathway acquire transformed phenotype (Fig 4), which is dependent on FGF signaling.

Prudovsky Fig 4Fig 4. Fibroblasts where Notch signaling is inhibited by a dn form of transcription factor CBF1 form tumors in chicken chorioallanthoic membrane (A) and produce highly angiogenic tumors in nude mice (B, PECAM staining).

Our aim is to understand the transcriptional regulation of nonclassical protein export by Notch signaling (Fig 5).

Prudovsky Fig 5Fig 5. Regulation of FGF1 expression and release by Notch signaling.

Restricted Proliferation of FGF-Stimulated Cells

We found that several cell types of mesenchymal origin respond to FGF presented as a single mitogen by a strictly limited proliferation. They undergo one cell cycle and then get blocked in the non-proliferating state characterized by dramatic accumulation of cell cycle inhibitors (Figure 6) and active FGFR/Erk signaling.

Prudovsky Fig 6Fig 6. Unlike serum-stimulated cells, FGF1 treated fibroblasts express large amounts of cell cycle inhibitor p21 (green).

We hypothesize that the restricted character of FGF-induced proliferative response prevents hyperplasia in damaged tissue, where FGF is released under stress conditions. We are currently studying the molecular mechanisms, which limit the growth of FGF-stimulated cells.

Kacer_Doreen_TDoreen Kacer

Research Associate II

A complete list of publications can be found on My NCBI

Kirov A, Kacer D, Conley BA, Vary CP, Prudovsky I. AHNAK2 Participates in the Stress-Induced Nonclassical FGF1 Secretion Pathway. Journal of cellular biochemistry. 2015; 116(8):1522-31. PubMed [journal] PMID: 25560297

Poole A, Knowland N, Cooper E, Cole R, Wang H, et al. Transitory FGF treatment results in the long-lasting suppression of the proliferative response to repeated FGF stimulation. Journal of cellular biochemistry. 2014; 115(5):874-88. NIHMSID: NIHMS632532 PubMed [journal] PMID: 24375433, PMCID: PMC4205782

Wang T, Green LA, Gupta SK, Kim C, Wang L, et al. Transfer of intracellular HIV Nef to endothelium causes endothelial dysfunction. PloS one. 2014; 9(3):e91063. PubMed [journal] PMID: 24608713, PMCID: PMC3946685

Danza G, Di Serio C, Ambrosio MR, Sturli N, Lonetto G, et al. Notch3 is activated by chronic hypoxia and contributes to the progression of human prostate cancer. International journal of cancer. Journal international du cancer. 2013; 133(11):2577-86. NIHMSID: NIHMS486217 PubMed [journal] PMID: 23729168, PMCID:PMC3788097

Gong Y, Yang X, He Q, Gower L, Prudovsky I, et al. Sprouty4 regulates endothelial cell migration via modulating integrin β3 stability through c-Src. Angiogenesis. 2013; 16(4):861-75. NIHMSID: NIHMS516697 PubMed [journal] PMID: 23955631, PMCID: PMC3790316

Sterling SM, Allgeyer ES, Fick J, Prudovsky I, Mason MD, et al. Phospholipid diffusion coefficients of cushioned model membranes determined via z-scan fluorescence correlation spectroscopy. Langmuir : the ACS journal of surfaces and colloids. 2013; 29(25):7966-74. NIHMSID: NIHMS487973 PubMed [journal] PMID: 23705855, PMCID: PMC3758428

Prudovsky I. Nonclassically Secreted Regulators of Angiogenesis. Angiology: open access. 2013; 1(1):1000101. NIHMSID: NIHMS549087 PubMed [journal] PMID: 24511556, PMCID: PMC3914728

Prudovsky I, Kumar TK, Sterling S, Neivandt D. Protein-phospholipid interactions in nonclassical protein secretion: problem and methods of study. International journal of molecular sciences. 2013; 14(2):3734-72. PubMed [journal] PMID: 23396106, PMCID: PMC3588068

Lopez-Castejon G, Luheshi NM, Compan V, High S, Whitehead RC, et al. Deubiquitinases regulate the activity of caspase-1 and interleukin-1β secretion via assembly of the inflammasome. The Journal of biological chemistry. 2013; 288(4):2721-33. PubMed [journal] PMID: 23209292, PMCID: PMC3554938

Prudovsky I, Vary CP, Markaki Y, Olins AL, Olins DE. Phosphatidylserine colocalizes with epichromatin in interphase nuclei and mitotic chromosomes. Nucleus (Austin, Tex.). 2012; 3(2):200-10. PubMed [journal] PMID: 22555604, PMCID: PMC3383575

Kirov A, Al-Hashimi H, Solomon P, Mazur C, Thorpe PE, et al. Phosphatidylserine externalization and membrane blebbing are involved in the nonclassical export of FGF1. Journal of cellular biochemistry. 2012; 113(3):956-66. NIHMSID: NIHMS333359 PubMed [journal] PMID: 22034063, PMCID: PMC3264788