Nagraj Sambrani

I recently completed my PhD at Institute of Developmental biology -Marseille (IBDML) , in the Team led by Jacques Pradel and Yacine Graba ( PhD Supervisor) .My project was aimed at understanding mechanism of Hox protein function in Drosophila melanogaster. I started working with flies in the year 2001 in CCMB, Hyderabad ,India , in the lab of LS.Shashidhara ,and this place taught me basics of Drosophila Genetics.

You can get in touch with me by using the contact form.

Research Experience / Resume:

Worked as research assistant (2001-2005) Centre for Cellular and Molecular Biology (CCMB) in Dr.Shashidhara’s Lab in project titled “Mechanism of Homeotic gene control in Drosophila”.This is the place where i learnt about beautiful fruit flies for the first time,which happens to by my favorite organism now.My work in CCMB included identifying the regulation aspects of an Ubx target which was differentially expressed between Wing and Haltere imaginal discs.

Key Findings:

Growth and patterning during Drosophila wing development are mediated by signaling from its dorso-ventral (D/V) organizer. Wingless is expressed in the D/V boundary and functions as a morphogen to activate target genes at a distance. Wingless pathway and thereby D/V signaling is negatively regulated by the homeotic gene Ultrabithorax (Ubx) to mediate haltere development. In an enhancer–trap screen to identify genes that show differential expression between wing and haltere discs, we identified CG32062, which codes for a RNA-binding protein. In wing discs, CG32062 is expressed only in non-D/V cells. CG32062 expression in non-D/V cells is dependent on Notch-mediated signaling from the D/V boundary. However, CG32062 expression is independent of Wingless function, thus providing evidence for a second long-range signaling mechanism of the D/V organizer. In haltere discs, CG32062 is negatively regulated by Ubx. The non-cell autonomous nature of Ubx-mediated repression of CG32062 expression suggests that the novel component of D/V signaling is also negatively regulated during haltere specification.

Publication:

Identification of a novel target of D/V signaling in Drosophila wing disc: Wg-independent function of the organizer
Ruchi Bajpai*, Nagraj Sambrani*, Bernd Stadelmayer and L. S. Shashidhara.

*These two authors have contributed equally to this work.

Gene Expression Patterns 5 (2004) 113–121

(PhD in developmental Biology Sep 2005- Dec 2009) Ibdml Marseille : Group of Yacine Graba and Jacques Pradel

I defended my thesis entitled ” Deciphering molecular mechanism underlying functional diversity of Hox proteins” on December 10, 2009 and subsequently awarded PhD by “Université de la Méditerranée” Marseille, France.

Publication:

A unique Extradenticle recruitment mode in the Drosophila Hox protein Ultrabithorax.
Merabet S, Saadaoui M, Sambrani N, Hudry B, Pradel J, Affolter M, Graba Y.
Proc Natl Acad Sci U S A. 2007 Oct 23;104(43):16946-51

Hox transcription factors are essential for shaping body morphology in development and evolution. The control of Hox protein activity in part arises from interaction with the PBC class of partners, pre-B cell transcription factor (Pbx) proteins in vertebrates and Extradenticle (Exd) in Drosophila. Characterized interactions occur through a single mode, involving a short hexapeptide motif in the Hox protein. This apparent uniqueness in Hox-PBC interaction provides little mechanistic insight in how the same cofactors endow Hox proteins with specific and diverse activities. Here, we identify in the Drosophila Ultrabithorax (Ubx) protein a short motif responsible for an alternative mode of Exd recruitment. Together with previous reports, this finding highlights that the Hox protein Ubx has multiple ways to interact with the Exd cofactor and suggests that flexibility in Hox-PBC contacts contributes to specify and diversify Hox protein function.

LAB @ CCMB(2002)

LAB @ CCMB(2004)

Present lab @ IBDML (2006)