The Protein Acyl Transferase ZDHHC21 Modulates α1 Adrenergic Receptor Function and Regulates Hemodynamics

Abstract

Objective Palmitoylation, the reversible addition of the lipid palmitate to a cysteine, can alter protein localization, stability, and function. The ZDHHC family of protein acyl transferases catalyzes palmitoylation of numerous proteins. The role of ZDHHC enzymes in intact tissue and in vivo is largely unknown. Herein, we characterize vascular functions in a mouse that expresses a nonfunctional ZDHHC21 (“F233Δ”). Approach and Results Physiological studies of isolated aortae and mesenteric arteries from F233Δ mice revealed an unexpected defect in responsiveness to phenylephrine, an α1 adrenergic receptor agonist. In vivo, F233Δ mice displayed a blunted response to infusion of phenylephrine and were found to have elevated catecholamine levels and elevated vascular α1 adrenergic receptor gene expression. Telemetry studies showed that the F233Δ mice were tachycardic and hypotensive at baseline, consistent with diminished vascular tone. In biochemical studies, ZDHHC21 was shown to palmitoylate the α1D adrenoceptor, and to interact with it in a molecular complex, thus suggesting a possible molecular mechanism by which the receptor can be regulated by ZDHHC21. Conclusions Together the data support a model in which ZDHHC21 F233Δ diminishes the function of vascular α1 adrenergic receptors, leading to reduced vascular tone which manifests in vivo as hypotension and tachycardia. This is to our knowledge the first demonstration of a ZDHHC isoform affecting vascular function in vivo and identifies a novel molecular mode of regulation of vascular tone and blood pressure.

Fatty acylation of proteins: The long and the short of it

“…Studies of mice with loss of function alleles or knockout of a single DHHC gene have uncovered distinct phenotypes [61]. For example, mice deficient in DHHC13 or DHHC17 exhibit neurological defects similar to Huntington disease [64, 65], while defects in vascular tone and hair follicle differentiation result when mice produce non-functional DHHC21 [66, 67]. …”

Palmitoyl acyltransferase DHHC21 mediates endothelial dysfunction in systemic inflammatory response syndrome

“…In our experiments, these mice were born at a normal gestational rate, were weaned into adulthood with no complications, and did not display obvious abnormalities in their basal cardiopulmonary or microcirculatory function. A more recent phenotypic characterization revealed attenuated α1 adrenergic-dependent vasomotor reactivity to phenylephrine and transient hypotension; however, no fluid imbalance, renal impairment or gross histological differences in the heart or kidney were found 33 . Importantly, endothelial-dependent vasodilation was unaffected, making the Zdhhc21 dep/dep model advantageous for studying barrier-specific regulation of fluid dynamics with minimized confounding variables from hemodynamics.…”

“…Comparing mRNAs from multiple tissues, Ohno et al showed that Zdhhcs 4 , 5 , 7 , 8 , 10 , 12 , 13 , 17 and 22 were ubiquitously expressed, while others were highly tissue-specific 36 . For example, Zdhhc11 was found only in testis, Zdhhc19 in testis, thymus and small intestine, and Zdhhc21 was found in multiple tissues including blood vessels, but is absent in leucocytes 33 36 . Within this context, although Zdhhcs 2, 3, 7, 8 and 21 have been identified in human umbilical vein endothelial cells 39 , our experiments are the first to screen endothelial cells from different vascular beds for expression of all 24 Zdhhcs .…”

“…Studies have also reported their involvement in Wnt-driven carcinogenesis 28 , insulin-promoted angiogenesis 29 , neurologic diseases 30 and metabolic disorders 31 32 . Most recently, an in vivo study demonstrated a role for DHHC21-PAT in mediating vasoconstriction by palmitoylating α-adrenergic receptor 33 , suggesting the possibility that PATs serve as an important dynamic regulator of circulatory functions.…”

Calcium-dependent protein acyltransferase DHHC21 controls activation of CD4+T cells

“…The spontaneous depilated ("dep") mutation of DHHC21 (Zdhhc21 dep , MGI:94884) was initially described as a recessive mutation on chromosome 4 characterized by variable hair loss and abnormal hair structure and was later mapped to the zdhhc21 gene (19,20). Delayed follicle differentiation, endothelial dysfunction and reduced vascular tone observed in Zdhhc21 dep mice (19,21,22) suggested that deletion of F233 causes a functional deficiency of DHHC21. However, the molecular mechanism underlying dysfunction of the F233 DHHC21 mutant remained unresolved.…”