Polysialic acid governs T-cell development by regulating progenitor access to the thymus.

Although the polysialyltransferase ST8Sia IV is expressed in both primary and secondary human lymphoid organs, its product, polysialic acid (polySia), has been largely overlooked by immunologists. In contrast, polySia expression and function in the nervous system has been well characterized. In this context, polySia modulates cellular adhesion, migration, cytokine response, and contact-dependent differentiation.

Targeting genes and transcription factors to segregated nuclear compartments.

With increasingly detailed images of nuclear structures revealed by advanced microscopy, a remarkably compartmentalized cell nucleus has come into focus. Although this complex nuclear organization remains largely unexplored, some progress has been made in deciphering the functional aspects of various subnuclear structures, revealing how this elaborate framework can influence gene activation. Several recent studies have helped illustrate how cells might utilize the nuclear architecture as an additional level of transcriptional control, perhaps by targeting genes and regulatory factors to specific sites within the nucleus that are designated for active RNA synthesis.