VAV2, a guanine nucleotide exchange factor for Rac1, regulates glucose-stimulated insulin secretion in pancreatic beta cells

Rajakrishnan Veluthakal, Ragadeepthi Tunduguru, Daleep Kumar Arora, Vaibhav Sidarala, Khadija Syeda, Cornelis P. Vlaar, Debbie C. Thurmond, Anjaneyulu Kowluru

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Aims/hypothesis: Rho GTPases (Ras-related C3 botulinum toxin substrate 1 [Rac1] and cell division cycle 42 [Cdc42]) have been shown to regulate glucose-stimulated insulin secretion (GSIS) via cytoskeletal remodelling, trafficking and fusion of insulin-secretory granules with the plasma membrane. GTP loading of these G proteins, which is facilitated by GDP/GTP exchange factors, is a requisite step in the regulation of downstream effector proteins. Guanine nucleotide exchange factor VAV2 (VAV2), a member of the Dbl family of proteins, has been identified as one of the GDP/GTP exchange factors for Rac1. Despite recent evidence on the regulatory roles of VAV2 in different cell types, roles of this guanine nucleotide exchange factor in the signalling events leading to GSIS remain undefined. Using immunological, short interfering RNA (siRNA), pharmacological and microscopic approaches we investigated the role of VAV2 in GSIS from islet beta cells. Methods: Co-localisation of Rac1 and VAV2 was determined by Triton X-114 phase partition and confocal microscopy. Glucose-induced actin remodelling was quantified by live cell imaging using the LifeAct-GFP fluorescent biosensor. Rac1 activation was determined by G protein linked immunosorbent assay (G-LISA). Results: Western blotting indicated that VAV2 is expressed in INS-1 832/13 beta cells, normal rat islets and human islets. Vav2 siRNA markedly attenuated GSIS in INS-1 832/13 cells. Ehop-016, a newly discovered small molecule inhibitor of the VAV2–Rac1 interaction, or siRNA-mediated knockdown of VAV2 markedly attenuated glucose-induced Rac1 activation and GSIS in INS-1 832/13 cells. Pharmacological findings were recapitulated in primary rat islets. A high glucose concentration promoted co-localisation of Rac1 and VAV2. Real-time imaging in live cells indicated a significant inhibition of glucose-induced cortical actin remodelling by Ehop-016. Conclusions/Interpretation: Our data provide the first evidence to implicate VAV2 in glucose-induced Rac1 activation, actin remodelling and GSIS in pancreatic beta cells.

Original languageEnglish
Pages (from-to)2573-2581
Number of pages9
JournalDiabetologia
Volume58
Issue number11
DOIs
StatePublished - Jul 31 2015

Fingerprint

Guanine Nucleotide Exchange Factors
Insulin-Secreting Cells
Insulin
Glucose
Guanosine Triphosphate
Small Interfering RNA
Actins
GTP-Binding Proteins
rac1 GTP-Binding Protein
Pharmacology
Immunosorbents
rho GTP-Binding Proteins
Secretory Vesicles
Biosensing Techniques
Islets of Langerhans
Confocal Microscopy
Cell Cycle
Proteins
Western Blotting
Cell Membrane

Keywords

  • Cytoskeleton
  • Insulin secretion
  • Pancreatic islet
  • Rac1
  • VAV2

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism

Cite this

Veluthakal, R., Tunduguru, R., Arora, D. K., Sidarala, V., Syeda, K., Vlaar, C. P., ... Kowluru, A. (2015). VAV2, a guanine nucleotide exchange factor for Rac1, regulates glucose-stimulated insulin secretion in pancreatic beta cells. Diabetologia, 58(11), 2573-2581. https://doi.org/10.1007/s00125-015-3707-4

VAV2, a guanine nucleotide exchange factor for Rac1, regulates glucose-stimulated insulin secretion in pancreatic beta cells. / Veluthakal, Rajakrishnan; Tunduguru, Ragadeepthi; Arora, Daleep Kumar; Sidarala, Vaibhav; Syeda, Khadija; Vlaar, Cornelis P.; Thurmond, Debbie C.; Kowluru, Anjaneyulu.

In: Diabetologia, Vol. 58, No. 11, 31.07.2015, p. 2573-2581.

Research output: Contribution to journalArticle

Veluthakal, R, Tunduguru, R, Arora, DK, Sidarala, V, Syeda, K, Vlaar, CP, Thurmond, DC & Kowluru, A 2015, 'VAV2, a guanine nucleotide exchange factor for Rac1, regulates glucose-stimulated insulin secretion in pancreatic beta cells', Diabetologia, vol. 58, no. 11, pp. 2573-2581. https://doi.org/10.1007/s00125-015-3707-4
Veluthakal, Rajakrishnan ; Tunduguru, Ragadeepthi ; Arora, Daleep Kumar ; Sidarala, Vaibhav ; Syeda, Khadija ; Vlaar, Cornelis P. ; Thurmond, Debbie C. ; Kowluru, Anjaneyulu. / VAV2, a guanine nucleotide exchange factor for Rac1, regulates glucose-stimulated insulin secretion in pancreatic beta cells. In: Diabetologia. 2015 ; Vol. 58, No. 11. pp. 2573-2581.
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AU - Sidarala, Vaibhav

AU - Syeda, Khadija

AU - Vlaar, Cornelis P.

AU - Thurmond, Debbie C.

AU - Kowluru, Anjaneyulu

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