Meera Srivastava, Ph.D
Meera Srivastava, Ph.D
Name: Meera Srivastava, Ph.D
Madras University, India BS 6/1972 Chemistry
Madras University, India MS 6/1974 Biochemistry
Indian Institute of Technology, New Delhi, India Ph.D. 6/1980 Biochemistry
My research has focused on the molecular basis of calcium signaling processes within cells. In early studies on chromaffin granules, which classically secrete catecholamines in response to a calcium pulse, attention was focused on the principal membrane protein cytochrome b561. This cytochrome is responsible for the unique process of vectorial electron transport across the membrane, and transfers electrons from ascorbic acid to dopamine beta hydroxylase (DBH) for the biosynthesis of norepinephrine from dopamine within the vesicle. I cloned the gene for this enzyme and interpreted the sequence in terms of a proposed transmembrane conformation. Later, when working in Dr. Pollard's lab looking for the human cytochrome b561 gene in a human library, I serendipitously isolated the long sought-for gene for human nucleolin. Aware of the critical importance of this gene for the maturation of ribosomes, I quickly moved to characterize and publish the description of this gene in the Journal of Biological Chemistry. This single author paper earned me an international reputation in a separate but related field of endeavor, in which I still contribute.
While at the NIH, I continued my interest in calcium signaling pathways by participating in the cloning the annexin 7 (ANX7) gene. Annexin 7 had been hypothesized to mediate calcium-activated membrane fusion occurring during exocytotic secretion. I determined that Anx7 was a single copy gene, characterized the exon-intron properties, and located the gene on chromosome 10q21(published in Biochemistry). I also extended this work to model organisms such as mouse and xenopus laevis, and discovered an ANX7 motif in HIV. The latter motif turned out to be of functional importance because deleting or replacing it resulted in loss of viability by the HIV virion (published in PNAS(USA)). Based on this and continuing work with site directed mutagenesis on human ANX7 by me, ANX7 is now known to be a Ca2+-activated GTPase with membrane fusion properties driven by not only calcium and GTP, but also PKC. In order to fully understand the function of the ANX7 gene in vivo, I also set about to prepare a knockout mouse for the Anx7 gene. As anticipated from the presumed importance of this gene, the Anx7(-/-) mouse had a lethal phenotype. However, the heterozygous Anx7(+/-) mouse was viable. However, the phenotype of this mutant mouse proved remarkable in terms of gender-specific growth characteristics: males grew to gigantic size. Specific organs in both males are females were very large. Islets of Langerhans were large enough to span the long axis of the pancreas. These islets of Langerhans were found to secrete insulin poorly, and to activate calcium signaling from intracellular pools quite inefficiently. In fact, the knockout mice had very low expression levels of the IP3Receptor located on the endoplasmic reticulum. (published in PNAS(USA)). Finally, when the Anx7(+/-) animals were approximately one year old they suddenly began to express tumors of various descriptions. On average, 30% of the mice developed these tumors, while none were noted in the normal littermate controls. I have conjectured that the deficiency in IP3R-dependent signaling might have consequences for defective apoptosis, since Ca2+ signaling through this channel is needed for the apoptotic process to occur in numerous biological examples.
I immediately turned to studies of human tumor cells and human tumors to see if the ANX7 gene were involved in neoplastic transformation or tumor biology. Initiating a collaboration with colleagues at NIH with tumor tissue microarrays, I discovered that ANX7 expression was vastly reduced prostate cancers characterized as hormone insensitive local recurrences or metastatic. Because of the large number of tumors access on the slides, approximately 1000 at a time, a P value for this conclusion was estimated to be P=.0001. I also found that about 30% of human prostate tumor cells had expressed either loss of heterozygosity (LOH, loss of one allele) or complete loss of both alleles for ANX7 (published in the PNAS(USA)). The method involved dissection of tumor cells from normal cells in samples of fresh-frozen prostate cancer, and analysis using the normal cells still in the sample of tumor tissue as controls. Thus, I was able to conclude that the mechanism of tumorigenesis might include mutational loss of at least one copy of the ANX7 gene. Interestingly, the locus of the ANX7 gene, 10q21, had been long hypothesized to contain an unknown tumor suppressor gene (TSG); I hypothesized that ANX7 might be this missing TSG. More recently, I have analyzed human breast cancers in the same way, and also found evidence of mutational loss of at least one of the two ANX7 alleles. Again, this occurred in about 30% of cases. In all cases, the loss of the ANX7 allele is accompanied by substantial reduction in expression by the remaining ANX7 gene.
In addition to this important work on the ANX7 gene, I have also being collaborating with Dr. Pollard and other colleagues in the Department on a study of cystic fibrosis. In particular, I developed genomic cDNA array technology for this and other Departmental use. The use of the arrays allowed me to conclude that the cause of massive lung damage in cystic fibrosis might be because of tonic upregulation of the TNFR/NFB pathway in affected lung epithelial cells (published in Molecular Medicine). The arrays developed by me have also been applied by me to studies on different tumor cell lines in which ANX7 gene expression is problematic, and collaboratively with other members of the Department and the University on important problems ranging from diabetes to brain injury.
Now, I am a skilled and experienced molecular biologist who has been at the cutting edge of research addressing the biology and biochemistry of the genes and proteins involved in kidney graft rejection, cancer, cystic fibrosis, inflammation, post-traumatic syndrome and major depressive disorder. I have extensive experience with cDNA microarrays, protein arrays, and antibody microarrays. Notably, I am the first author on the first paper to ever demonstrate the remarkable power of antibody microarrays for the identification of clinically relevant, low abundance serum biomarker proteins (Srivastava el al, 2006).
I have published my work in 90 peer reviewed articles. I am co-author of a patent on the ANX7 gene with Dr. Pollard and drug development for ERG fusion gene in Prostate cancer with Dr. Srivastava and Dr. Dalgard.
Representative publications, projects, and/or deployments
- 1980-1982 Research Associate, Indian Institute of Technology, New Dehli, India.
- 1982-1983 Post-doctoral Research Associate, Auburn, Univ., Alabama.
- 1983-1984 Post-doctoral Fellow, Biochemistry Dept., Georgetown Univ., School of Medicine, Washington, DC.
- 1984-1986 Research Associate, Biochemistry Dept., Georgetown Univ. School of Med., Washington, DC.
- 1986-1987 Visiting Associate, LCBG, NIDDK, NIH, Bethesda, MD.
- 1987-1989 Research Instructor, Biochemistry Dept., Georgetown Univ. School of Med., Washington, DC.
- 1989-1991 Senior Staff Fellow, Food and Drug Administration, Rockville, MD
- 1991-1996 Senior Staff Fellow, LCBG, NIDDK, NIH, Bethesda, MD
- 1996-2002 Associate Professor, Dept. of Anat., Phy. and Genetics, USUHS, Bethesda, MD
- 2002-Present Research Professor, Dept. of Anat., Phy. and Genetics, USUHS, Bethesda,
- Srivastava, M., Duong Le T. and Fleming, P.J. (1984). Cytochrome b561 catalyzes transmembrane electron transfer. J. Biol. Chem.. 259: 8072-8075.
- Srivastava, M., McBride, O.W., Fleming, P.J., Pollard, H.B. and Burns, A.L. (1990) Genomic organization and chromosoaml localization of the human nucleolin gene. J. Biol. Chem., 265:14922-14931.
- Srivastava, M., Atwater, I., Glassman, M., Leighton, X., Goping, G., Miller, G., Mears, D., Rojas, E. and Pollard, H.B. (1999) Defects in IP3 Receptor Expression, Ca2+-Signaling and Insulin Secretion in the Anx7 (+/-) Knockout Mouse. Proc. Natl. Acad. Sci. 96,13783-13788
- Srivastava, M., Bubendorf, L., L., Nolan, L., Glasman, M., Leighton, X., Koivisto, P., Willi, N., Gasser, T., Kononen, J., Sauter, G., Kallioniemi, O.P., Srivastava, S. and Pollard, H.B. (2001) ANX7, a candidate tumor-suppressor gene for prostate cancer. Proc. Natl. Acad. Sci. 98, 4575-4580.
- Srivastava, M., Glasman, M., Leighton, X, Miller, G., Montagna, C., Reid, T., and Pollard, H.B. Genomic instability and gene expression profile in cancer prone Anx7(+/-) knockout mouse and cell line models. Proc Natl Acad Sci U S A. 2003; 100, 14287-14292.
- Srivastava, M., Bubendorf , L., Raffeld, M., Bucher, C., Torhorst, J., Sauter, G., Olsen, C., Kallioniemi, O.P., Eidelman, E. and Pollard, H.B. Prognostic impact of ANX7-GTPase in metastatic and HER2 negative breast cancer patients. 2004 Clin. Can. Res 10:2344-50.
- Srivastava, M., Eidelman, E Zhang, J Paweletz, C., Caohuy, H., Yang, O.F., Jacobson, K.A., Heldman, E, Huang, W., Jozwik, C., Pollard, B.S. and Pollard, H.B. Digitoxin mimics gene therapy with CFTR and suppresses hypersecretion of IL-8 from cystic fibrosis lung epithelial cells. Proc Natl Acad Sci U S A. 2004; 101, 7693-7698.
- Torosyan Y, Dobi A, Naga S, Mezhevaya K, Glasman M, Norris C, Jiang G, Mueller G, Pollard H, Srivastava M. Distinct Effects of Annexin A7 and p53 on Arachidonate Lipoxygenation in Prostate Cancer Cells Involve 5-Lipoxygenase Transcription. Cancer Res. 2006 Oct 1;66(19):9609-16.
- Torosyan Y, Dobi A, Glasman M, Mezhevaya K, Naga S, Huang W, Paweletz C, Leighton X, Pollard HB, Srivastava M. Role of multi-hnRNP nuclear complex in regulation of tumor suppressor ANXA7 in prostate cancer cells. Oncogene. 2010. 29(17):2457-66
- Leighton X, Eidelman O, Jozwik C, Pollard HB, Srivastava M. ANXA7-GTPase as Tumor Suppressor: Mechanisms and Therapeutic Opportunities. Methods Mol Biol. 2017;1513:23-35.