The Wnt Co-Receptor PTK7/Otk and Its Homolog Otk-2 in Neurogenesis and Patterning.

Wnt signaling is a highly conserved metazoan pathway that plays a crucial role in cell fate determination and morphogenesis during development. Wnt ligands can induce disparate cellular responses. The exact mechanism behind these different outcomes is not fully understood but may be due to interactions with different receptors on the cell membrane. PTK7/Otk is a transmembrane receptor that is implicated in various developmental and physiological processes including cell polarity, cell migration, and invasion. Here, we examine two roles of Otk-1 and Otk-2 in patterning and neurogenesis. We find that Otk-1 is a positive regulator of signaling and Otk-2 functions as its inhibitor. We propose that PTK7/Otk functions in signaling, cell migration, and polarity contributing to the diversity of cellular responses seen in Wnt-mediated processes.

An Optogenetic Method to Study Signal Transduction in Intestinal Stem Cell Homeostasis.

Homeostasis in adult organs involves replacement of cells from a stem cell pool maintained in specialized niches regulated by extracellular signals. This cell-to-cell communication employs signal transduction pathways allowing cells to respond with a variety of behaviors. To study these cellular behaviors, signaling must be perturbed within tissues in precise patterns, a technique recently made possible by the development of optogenetic tools. We developed tools to study signal transduction in vivo in an adult fly midgut stem cell model where signaling was regulated by the application of light. Activation was achieved by clustering of membrane receptors EGFR and Toll, while inactivation was achieved by clustering the downstream activators ERK/Rolled and NFκB/Dorsal in the cytoplasm, preventing nuclear translocation and transcriptional activation. We show that both pathways contribute to stem and transit amplifying cell numbers and affect the lifespan of adult flies. We further present new approaches to overcome overexpression phenotypes and novel methods for the integration of optogenetics into the already-established genetic toolkit of Drosophila.

WNT Signaling in Disease.

Developmental signaling pathways control a vast array of biological processes during embryogenesis and in adult life. The WNT pathway was discovered simultaneously in cancer and development. Recent advances have expanded the role of WNT to a wide range of pathologies in humans. Here, we discuss the WNT pathway and its role in human disease and some of the advances in WNT-related treatments.

Smoking spaces as enabling spaces of wellbeing.

A persistent emphasis on the negative biomedical effects of cigarette smoking effectively glosses over the affectual-sensual and social wellbeing that smoking can enable. In addition, while tobacco research has recently been more attuned to the stigmatizing affects brought about by smoking de-normalization efforts, a lot less attention has been placed on how smokers negotiate these feelings of stigmatization so as to restore their personal spaces of wellbeing. In this paper, I situate my investigation of smoking geographies in the burgeoning literature on enabling spaces which focuses on how places co-constitute our ability to act/affect in empowering ways. By deploying qualitative research methods such as in-depth interviews, I argue that an acknowledgment of how smoking spaces in Singapore can be enabling along affectual, sensorial and social registers is long overdue. While it is not my purpose to systematically downplay the damaging health effects that smoking can engender, a focus on enabling smoking spaces emphasizes the role of smokers as creative agents capable of (re)fashioning their own holistic and subjective versions of wellbeing. In so doing, I hope to contribute to the existing research on smoking spaces and a recent profusion of work on relational geographies of affect.