Research interests

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Prof. Kasturi Datta has made significant contributions in the field of Biochemistry, Molecular and Reproductive Biology to unravel the molecular mechanism of several mammalian physiological processes like cardiac gene expression, metabolic regulation of heme biosynthesis and cell matrix interaction in sperm function and cell transformation.

Her studies on the biogenesis of cardiac cells in relation to the expression of cardiac muscle specific genes e.g. myosin heavy chain and myosin light chain is well accepted. She has successfully done the molecular cloning of myosin heavy chain and glyceraldehyde 3-phosphate dehydrogenase and showed their specific expression in rat cardiac tissues.

In the area of metabolic regulation, she has also established a new route for the synthesis of d-amino levulinic acid, the important precursor of heme in mammalian system, by mitochondrial matrix enzyme L-alanine dioxovalerate transaminase. She further confirmed that this enzyme functions as an important source to maintain the housekeeping level of d-aminolevulinic acid, regulatory step for heme biosynthesis.

Among several scientific achievements, her recent research activities have enlighten us in understanding the molecular basis of cell matrix and cell-cell interaction during signal transduction cascade in transformed cells and in sperm-oocyte interaction. Her outstanding contribution in this area includes identification and purification of a novel cell surface glycoprotein, which binds specifically to hyaluronic acid (HA), a complex polysaccharide present ubiquitously in extracellular matrix (ECM) and involved in cellular differentiation and various physio-pathological conditions. The work of Prof. Datta's laboratory has established the physiological significance of this protein, since it expresses differentially on transformed cells, promotes cell adhesion and regulates tumor formation and sperm function. The ubiquitous presence of HABP1 in different cells was demonstrated by her group and a gradual decline in the level of hyaluronan binding protein during progression of myoblast differentiation was shown. Interestingly, enhanced cellular phosphorylation of hyaluronic acid binding protein and its role in cellular signalling has been demonstrated in transformed cells, as well as hyaluronic acid treated cells. Her recent  report  that being a bonafide MAP Kinase substrate, HABP1 may translocate to nucleus upon mitogenic stimulation and regulate the process of cell signalling  is an important observation.

In order to work into its precise role, the gene encoding human hyaluronan binding protein has been cloned by immunoscreening the human fibroblast expression library and overexpressed in different expression system (Accession No. AF275902). Sequence analysis of cDNA encoding hyaluronan binding protein was shown to be identical with p32, a protein copurified with splicing factor SF2, whose function was unknown. She was able to demonstrate that the overexpressed protein could bind to biotinylated hyaluronan, thus availing the functionally active recombinant hyaluronan  binding  protein.  After obtaining the clone and functionally active rHABP1, she continued her work to assign the biological function of this gene using the knowledge of different areas like bioinformatics, structural biology , cell and molecular biology.

Prof. Datta's laboratory further highlighted the multifunctional nature of this protein as its sequence is homologous with  the  receptor  of  globular  head  of C1q (the complement protein) and a murine protein (YL2), that binds with HIV Type 1 Rev.  This work was recognized internationally as Human Genome Project Nomenclature committee had given the name HABP1 to this novel gene and synonym of gC1QBP  and  SF2p32,   suggested   by   her   group.   She  has  further reported the localization of hyaluronic acid binding protein (HABP1) on human chromosome 17p12-p13.

Using the functionally active purified rHABP1, her group has demonstrated not only its oligomeric transition, but also the enhanced ligand affinity with the dimer of its asymmetric trimeric crystal. This knowledge of structural aspect of HABP1 with its functionality in terms of HA affinity unravels its intricate regulation on signalling. Currently, her group is engaged in unraveling the structure function relationship of HABP1 by modifying some specific amino acids with a view to distort various motifs present in it and analysing its affinity towards hyaluronan and other known ligands.

Scientific ContributionS: Prof. Kasturi datta

Prof. Kasturi Datta has made significant contributions in the field of Biochemistry, Cellular and Molecular Biology. The unifying theme of her research has been to unravel the various molecular mechanisms involved in metabolic regulation and in signal transduction pathway induced by stimuli, a pertinent question to be answered in the area of Life Science. The remarkable feature of Prof. Datta’s career has been that most of her significant contributions have come from work done in India as an independent investigator. She has also been extremely prolific in her short visits abroad, as a visiting Scientist. The salient features of her contributions are as follows:

1.   Cardiac muscle specific gene expression

During the post-doctoral training and as visiting Scientist in Roche Institute of Molecular Biology, Prof. Datta was interested to study the biogenesis of cardiac cells in relation to the expression of cardiac muscle specific genes e.g. myosin heavy chain and myosin light chain. Initially Prof. Datta reported the isolation and purification of a novel heat stable serum factor, responsible specifically for the beating of heart cells in culture. Later on, she has successfully done the molecular cloning of myosin heavy chain and glyceraldehyde 3-phosphate dehydrogenase and showed their specific expression in cardiac tissue. The promoter activity of myosin light chain and presence of transacting factor in cardiac cell line has also been reported by her.

2.   Enzyme Regulation and Metabolism

 Her work at Jawaharlal Nehru University has established a new route for the synthesis of d-amino levulinic acid, the important precursor of heme in mammalian system, by mitochondrial matrix enzyme L-alanine dioxovalerate transaminase. In order to understand it in details, she has shown a cytosolic form of this enzyme, which differs from the mitochondrial form. This form can be the cytosolic precursor of this enzyme. Using alanine DOVA transaminase as a model system, she studied the mechanism of translocation of matrix protein through mitochondrial membrane. Total polyadenylated RNA, isolated from rat kidney, was translated in vitro using rabbit reticulocyte cell free translation system and L-alanine: DOVA transminase was estimated by indirect immunoprecipitation. With this approach, she reported that in vitro translocation of L-alanine: DOVA transminase into rat kidney mitochondria remains unaffected in the presence of hemin. Her studies provide an important contribution in this field, indicating that unlike the other enzyme of heme biosynthesis pathway (i.e. ALA synthetase), this enzyme is not under tight regulation by heme, but nonetheless functions as an important source to maintain a housekeeping level of d-aminolevulinic acid, which regulates the formation of biologically active heme proteins in mammalian system.

 Cell matrix and cell interaction during signal transduction in transformed cell and sperm oocyte interaction

 In the last few years, research activities undertaken by Prof. Kasturi Datta have enlightened us in understanding the molecular basis of involvement of cellular matrix proteins in cell-cell interaction; signal transduction in transformed cells and in the sperm-oocyte interaction. Her outstanding contribution in this area includes identification and purification of a novel cell surface glycoprotein, which binds specifically to hyaluronic acid (HA), a complex polysaccharide present ubiquitously in extracellular matrix (ECM) and involved in cellular differentiation and various pathological conditions (Euro. J. Cell Biol.; 56(1), 58-67, 1991). The work of Prof. Datta's laboratory has established the physiological significance of this protein, since it expresses differentially on transformed cells, promotes cell adhesion and regulates tumor formation (Expt. Cell Res.; 195(2), 386-394, 1991) and sperm function (Mol. Reprod. Dev.; 38, 69-76, 1994). The ubiquitous presence of this hyaluronan binding protein in different cells was demonstrated by her group and a gradual decline in the level of hyaluronan binding protein during progression of myoblast differentiation was also shown (Cell Biol. Int.; 40, 327-427, 1995).

In order to elucidate its precise role, the gene encoding human hyaluronan binding protein has been cloned by immunoscreening the human fibroblast expression library and overexpressed in different expression systems (Accession No. AF275902). Sequence analysis of cDNA encoding hyaluronan binding protein was shown to be identical with p32, a protein which copurifies with splicing factor SF2, whose function was unknown. She was able to demonstrate that the overexpressed protein could bind to biotinylated hyaluronan, thus availing the functionally active recombinant hyaluronan binding protein (J. Biol. Chem.; 269, 2206-2212, 1996).  After obtaining the clone and the functionally active recombinant hyaluronan binding protein, she continued her work in assigning biological function to this gene, using the knowledge of bioinformatics, structural biology, cellular and molecular biology.

With sequence search analysis, Prof. Datta's laboratory further highlighted the multifunctional nature of this protein as its sequence is homologous with the receptor of globular head of C1q (the complement protein) and a murine protein (YL2), that binds with HIV Type 1 Rev (Gene; 190, 223-225, 1997).  The Human Genome Project Nomenclature committee recognized this work internationally and the name HABP1 was assigned by her group placed one gene on human genome project from India. She has further reported the localization of HABP1 on human chromosome 17p12-p13 (Genomics; 51, 476-477, 1998).

In order to assign the biological function of HABP1, her group followed the approach of functional genomics in studying its specific expression, structure function relationship, genomic analysis and genetic manipulations of its constitutive expression. Interestingly, they have reported the presence of HABP1 pseudogene at multiple locations of mammalian genome like chromosome 4,11,15 and 21 and also studied their phylogenic tree (DNA & Cell Biol., 21(10), 727-735, 2002) and (DNA and Cell Biol.23, 301-210, 2004).

Using the functionally active purified recombinant HABP1, her group has demonstrated not only its oligomeric transition, but also the enhanced ligand affinity with the dimer of its asymmetric trimeric crystal. This knowledge of structural aspect of HABP1 with its functionality in terms of HA affinity unravels its intricate regulation on signalling (Eur. J. Biochem. 269, 298-307, 2002). In continuation, her group reported recently the structural flexibility of multifunctional HABP1 is an important criteria which regulates its binding to different ligands (J. Biol. Chem. 278(30) 27464-27472 2003). Her work extended to demonstrate the unique feature of this protein having ionic dependent structural transition which reflects on its thermodynamic stability (J. Biol. Chem. 279(22) 23061-23072, 2004). Recently, her group also unraveled the structure-function relationship of HABP1 by modifying some specific amino acids with a view to distort various motifs present in this multifunctional protein and analyzed not only its affinity towards hyaluronan and other known ligands, but showed its ability to generate morphological aberration and perturbation in growth in COS cells (Biochem. J. 380, 837-844, 2004) .

Interestingly, enhanced cellular phosphorylation of hyaluronic acid binding protein and its role in cellular signalling has been demonstrated in transformed cells and hyaluronic acid treated cells (Biochem. Biophys. Res. Commun.; 177(3), 1291-1298, 1991; Biochim. Biophys. Acta.; 1336, 383-387, 1997). Her recent  report  that being a bonafide MAP Kinase substrate, this protein translocates to nucleus upon mitogenic stimulation and regulates the process of cell signalling, is an important observation (Biochem. Biophys. Res. Commun. 291, 829-837, 2002). In continuation we confirmed the overexpression of HABP1 in cispletin induced apoptosis HeLa cells.  (Apoptosis March, 2006).

As a part of the ongoing research programme, the biological function of HABP1 was examined by altering the constitutive level of expression of HABP1 in simple eukaryote e.g. S. pombe and mammalian cells e.g. normal and transformed fibroblasts. They found that overexpression of HABP1 in S. pombe leads to multinucleation, abnormal cell septum formation and growth inhibition and able to demonstrate its specific interaction with cdc25, suggesting its role in cell cycle. (Exp.Cell Res. 309 250-263 2005). To support they further observed that the stable expressing constitutively HABP1 in normal fibroblasts perturbs its growth characteristics and induces apoptosis, confirming its precise role in cellular function (Biochem. Biophys. Res. Commun. 300(3), 686-693, 2003).

In parallel of the above mentioned work, the role of hyaluronic acid binding protein in sperm function also has been examined by their group, since HA is an important component of reproductive fluid. Interestingly, this 34-kDa hyaluronic acid binding protein is present on sperm surface and its level is altered during epididymal maturation. The inhibition of sperm-oocyte interaction by treating sperms with anti-HABP1 antibody has been successfully demonstrated, thus clarifying its role in fertilization (Mol. Reprod. Dev. 38, 69-76, 1994). This observation is further supported by the enhanced phosphorylation of HABP1 with HA-induced sperm motility. The proprotein form of HABP1 expressing specifically in testis, but not in other somatic tissues, is detected in elongating spermatids, whereas the mature form is present only on epididymal and ejaculated spermatozoa. Their data suggest the presence of only the proprotein form of HABP1 in the cytoplasm of round spermatids and pachytene spermatocytes of testicular sections (Mol. Reprod. Dev. 62(2): 223-232, 2002) and shown to be developmentally regulated (J. of Andrology, 2006), in addition to the reduced expression of mature form of HABP1 in the spermatozoa of male infertile patients (J. Reprod. Immunol. 53(1-2), 45-54, 2001). Recent data from their laboratory indicates the interaction of sperm surface HABP1 with zona pellucida of water buffalo, through its clustered mannose residues, indicating its participation in sperm zona interaction. Further, the addition of rHABP1 in the medium allows spermoocyte interaction with the sperm otherwise was unable to interact with zona (Mol. Rep. Dev. 64(2), 235-244, 2003). Further work on experimental crytorchidic condition, with abolition of spermatogenesis the presence giant cell formation coincides with elevated level of HABP1. All these observations strongly suggest the use of HABP1 as a marker of male infertility and to identify the stages of arrest of germ cell differentiation in testicular biopsies, and may be used in IVF medium as potent sperm zona inducer.

In short, her group initially identified a novel protein from rat tissue that has specific affinity towards hyaluronan and was immunologically cross-reactive with human tissue. Utilizing this observation, they identified the human homologue of this gene by immunoscreening the expression library, named it HABP1, confirmed its localization on human chromosome 17p13.3 and placed this novel gene on the map of human genome project. Her continued effort confirmed the multifunctionality of this protein; established its role in cellular signalling; studied the oligomeric behaviour of this protein with special reference to its functional implications exhibited the inhibitory effect on cell growth if overexpressed in simple eukaryotic cells and mammalian cell lines; induces apoptosis by generating reactive oxygen species and increasing mitochondrial Ca++ influx; may act as cell cycle regulatory protein and lastly the use of HABP1 as a tool in understanding the process of spermatogenesis and in diagnosis for male infertility.