STARD13

StAR-related lipid transfer domain protein 13 (STARD13) also known as deleted in liver cancer 2 protein (DLC-2) is a is_associated_with::protein that in humans is encoded by the STARD13 is_associated_with::gene and a member of the DLC family of proteins.

Function and structure
STARD13 serves as a Rho GTPase-activating protein (GAP), a type of protein that regulates members of the is_associated_with::Rho family of GTPases. It selectively activates is_associated_with::RhoA and is_associated_with::CDC42 and suppresses cell growth by inhibiting is_associated_with::actin stress fiber assembly.

The protein consists of an N-terminal is_associated_with::sterile alpha motif (SAM) domain, a serine-rich domain, a is_associated_with::RhoGAP domain and at the C-terminus, a StAR-related lipid-transfer domain (START).

Tissue distribution and pathology
The protein was identified in part through its differential expression in is_associated_with::cancers. A low level of STARD13 was observed in less differentiated is_associated_with::hepatocellular carcinoma tissue with higher RhoA expression. A small patient study finds that the absence of STARD13 in hepatocellular carcinomas correlates with higher levels of RhoA and a poorer is_associated_with::prognosis than patients with carcinomas that were STARD13-positive.

Model organisms
is_associated_with::Model organisms have been used in the study of STARD13 function. A conditional is_associated_with::knockout mouse line, called Stard13tm1a(KOMP)Wtsi was generated as part of the is_associated_with::International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists — at the is_associated_with::Wellcome Trust Sanger Institute.

Male and female animals underwent a standardized is_associated_with::phenotypic screen to determine the effects of deletion. Twenty four tests were carried out on is_associated_with::mutant mice and two significant abnormalities were observed. Female homozygous mutants had an increased susceptibility to is_associated_with::Citrobacter infection and displayed a decreased is_associated_with::hematocrit and is_associated_with::hemoglobin content.

Another study of mice lacking STARD13, found it may promote is_associated_with::blood vessel formation (is_associated_with::angiogenesis), especially by tumor cells. The promotion of angiogenesis with the loss of STARD13 occurs through the actions of RhoA.