Stimulation of insulin secretion by glucose and other secretagogues from pancreatic islet beta-cells is mediated by multiple signaling pathways. Rac1 is a member of Rho family GTPases regulating cytoskeletal organization, and recent evidence also implicates Rac1 in exocytotic processes. Herein, we report that exposure of insulin-secreting (INS) cells to stimulatory glucose concentrations caused...

Transforming growth factor (TGF)-beta is a central mediator in the progression of glomerulosclerosis, leading to accumulation of aberrant extracellular matrix proteins and inappropriate expression of smooth muscle alpha-actin in the kidney. Previously, we reported that disrupting the cytoskeleton diminished TGF-beta-stimulated type I collagen accumulation in human mesangial cells. As cytoskelet...

Rac GTPases have been implicated in the regulation of diverse functions in various blood cell lineages, but their role in T-cell development is not well understood. We have carried out conditional gene targeting to achieve hematopoietic stem cell (HSC)- or T-cell lineage-specific deletion of Rac1 or Rac1/Rac2 by crossbreeding the Mx-Cre or Lck-Cre transgenic mice with Rac1(loxp/loxp) or Rac1(lo...

Rac1 is a member of the Rho family of small GTPases that control cells proliferation, differentiation, migration, and inflammation. Rac1 is crucial in tumorigenesis and development. Keratin17 and CD11b+Gr1+ cells are considered to regulate skin inflmmation. Here we discuss the regulation of Rac1 on skin tumor formation and its relationship. In samples from human skin squamous cell carcinoma (SC...

Rac GTPases are activated by extracellular stimuli and contribute to cellular responses including cytoskeletal changes and cell migration. Dominant-negative Rac1 has been used to implicate Rac GTPases in these responses, but which of the three mammalian Rac isoforms it inhibits is not known. We show that mouse bone marrow-derived macrophages express Rac1, low levels of Rac2 but not Rac3. As Rac...

Tiam1 is a rac1-specific guanine nucleotide exchange factor, and Tiam1-rac1 is involved in a number of cellular processes. Rac1 and RhoA act as molecular switches that cycle between GTP- and GDP-bound states to balance the activities of rac1 and RhoA. The downregulation of rac1 activity leads to upregulation of RhoA activity, which promotes invasion and migration of pancreatic cancers cells. At...

Rac1, a member of the Rho family of small GTPases, has been shown to promote formation of lamellipodia at the leading edge of motile cells and affect cell migration. We previously demonstrated that calmodulin can bind to a region in the C-terminal of Rac1 and that this interaction is important in the activation of platelet Rac1. Now, we have analyzed amino acid residue(s) in the Rac1-calmodulin...

Rho family GTPases are primary mediators of cytoskeletal reorganization, although they have also been reported to regulate cell secretion. Yet, the extent to which Rho family GTPases are activated by secretory stimuli in neural and neuroendocrine cells remains unknown. In bovine adrenal chromaffin cells, we found Rac1, but not Cdc42, to be rapidly and selectively activated by secretory stimuli ...

BACKGROUND Ras-related C3 botulinum toxin substrate 1 (Rac1) is implicated in a variety of cellular functions and is related to tumor growth and metastasis. This study aimed to explore the role of Rac1 in hypopharyngeal squamous cell carcinoma (HSCC). MATERIAL AND METHODS The Rac1 expression in HSCC tissues was determined by quantitative real-time polymerase chain reaction and Western blot anal...

Actin in migrating cells is regulated by Rho GTPases. However, Rho proteins might also affect microtubules (MTs). Here, we used time-lapse microscopy of PtK1 cells to examine MT regulation downstream of Rac1. In these cells, "pioneer" MTs growing into leading-edge protrusions exhibited a decreased catastrophe frequency and an increased time in growth as compared with MTs further from the leadin...